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  • 1.
    Abdi, Amir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Numerical Investigation of Latent Thermal Storage in a Compact Heat Exchanger Using Mini-Channels2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 13, p. 5985-, article id 5985Article in journal (Refereed)
    Abstract [en]

    This paper aims to numerically investigate the thermal enhancement of a latent thermal energy storage component with mini-channels as air passages. The investigated channels in two sizes of internal air passages (channel-1 with d(h) = 1.6 mm and channel-2 with d(h) = 2.3 mm) are oriented vertically in a cuboid of 0.15 x 0.15 x 0.1 m(3) with RT22 as the PCM located in the shell. The phase change is simulated with a fixed inlet temperature of air, using ANSYS Fluent 19.5, with a varying number of channels and a ranging air flow rate entering the component. The results show that the phase change power of the LTES improves with by increasing the number of channels at the cost of a decrease in the storage capacity. Given a constant air flow rate, the increase in the heat transfer surface area of the increased number of channels dominates the heat transfer coefficient, thus increasing the mean heat transfer rate (UA). A comparison of the channels shows that the thermal performance depends largely on the area to volume ratio of the channels. The channel type two (channel-2) with a slightly higher area to volume ratio has a slightly higher charging/discharging power, as compared to channel type one (channel-1), at a similar PCM packing factor. Adding fins to channel-2, doubling the surface area, improves the mean UA values by 15-31% for the studied cases. The variation in the total air flow rate from 7 to 24 L/s is found to have a considerable influence, reducing the melting time by 41-53% and increasing the mean UA values within melting by 19-52% for a packing factor range of 77.4-86.8%. With the increase in the air flow rate, channel type two is found to have considerably lower pressure drops than channel type one, which can be attributed to its higher internal hydraulic diameter, making it superior in terms of achieving a relatively similar charging/discharging power in exchange for significantly lower fan power. Such designs can further be optimized in terms of pressure drop in future work, which should also include an experimental evaluation.

  • 2.
    Ahmad, Sarosh
    et al.
    Govt Coll Univ Faisalabad, Dept Elect Engn & Technol, Faisalabad 38000, Pakistan.;Univ Carlos III Madrid, Dept Signal Theory & Commun, Madrid 28911, Spain..
    Manzoor, Bilal
    Univ Engn & Technol UET, Dept Telecom Engn, Taxila 47050, Pakistan..
    Paracha, Kashif Nisar
    Govt Coll Univ Faisalabad, Dept Elect Engn & Technol, Faisalabad 38000, Pakistan..
    Haider, Sajjad
    King Saud Univ, Coll Engn, Chem Engn Dept, POB 800, Riyadh 11421, Saudi Arabia..
    Liaqat, Maryam
    Univ Okara UO, Dept Phys, Okara 56300, Pakistan..
    Al-Gburi, Ahmed Jamal Abdullah
    Univ Tekn Malaysia Melaka UTeM, Ctr Telecommun Res & Innovat CeTRI, Dept Elect & Comp Engn FKEKK, Durian Tungal 76100, Malaysia..
    Ghaffar, Adnan
    Auckland Univ Technol, Dept Elect & Elect Engn, Auckland 1010, New Zealand..
    Alibakhshikenari, Mohammad
    Univ Carlos III Madrid, Dept Signal Theory & Commun, Madrid 28911, Spain..
    Dalarsson, Mariana
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering.
    A Wideband Bear-Shaped Compact Size Implantable Antenna for In-Body Communications2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 6, p. 2859-, article id 2859Article in journal (Refereed)
    Abstract [en]

    Biomedical implantable antennas play a vital role in medical telemetry applications. These types of biomedical implantable devices are very helpful in improving and monitoring patients' living situations on a daily basis. In the present paper, a miniaturized footprint, thin-profile bear-shaped in-body antenna operational at 915 MHz in the industrial, scientific, and medical (ISM) band is proposed. The design is a straightforward bear-shaped truncated patch excited by a 50-Omega coaxial probe. The radiator is made up of two circular slots and one rectangular slot at the feet of the patch, and the ground plane is sotted to achieve a broadsided directional radiation pattern, imprinted on a Duroid RT5880 roger substrate with a typical 0.254-mm thickness (epsilon(r) = 2.2, tan delta = 0.0009). The stated antenna has a complete size of 7 mm x 7 mm x 0.254 mm and, in terms of guided wavelength, of 0.027 lambda(g) x 0.027 lambda(g) x 0.0011 lambda(g). When operating inside skin tissues, the antenna covers a measured bandwidth from 0.86 GHz to 1.08 GHz (220 MHz). The simulations and experimental outcomes of the stated design are in proper contract. The obtained results show that the calculated specific absorption rate (SAR) values inside skin of over 1 g of mass tissue is 8.22 W/kg. The stated SAR values are lower than the limitations of the federal communications commission (FCC). Thus, the proposed miniaturized antenna is an ultimate applicant for in-body communications.

  • 3.
    Ahmed, Faisal
    et al.
    Department of Computer Science and Engineering, Premier University, Chattogram 4000, Bangladesh.
    Hossain, Mohammad Shahadat
    Department of Computer Science and Engineering, University of Chittagong, Chittagong 4331, Bangladesh.
    Islam, Raihan Ul
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    An Evolutionary Belief Rule-Based Clinical Decision Support System to Predict COVID-19 Severity under Uncertainty2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 13, article id 5810Article in journal (Refereed)
    Abstract [en]

    Accurate and rapid identification of the severe and non-severe COVID-19 patients is necessary for reducing the risk of overloading the hospitals, effective hospital resource utilization, and minimizing the mortality rate in the pandemic. A conjunctive belief rule-based clinical decision support system is proposed in this paper to identify critical and non-critical COVID-19 patients in hospitals using only three blood test markers. The experts’ knowledge of COVID-19 is encoded in the form of belief rules in the proposed method. To fine-tune the initial belief rules provided by COVID-19 experts using the real patient’s data, a modified differential evolution algorithm that can solve the constraint optimization problem of the belief rule base is also proposed in this paper. Several experiments are performed using 485 COVID-19 patients’ data to evaluate the effectiveness of the proposed system. Experimental result shows that, after optimization, the conjunctive belief rule-based system achieved the accuracy, sensitivity, and specificity of 0.954, 0.923, and 0.959, respectively, while for disjunctive belief rule base, they are 0.927, 0.769, and 0.948. Moreover, with a 98.85% AUC value, our proposed method shows superior performance than the four traditional machine learning algorithms: LR, SVM, DT, and ANN. All these results validate the effectiveness of our proposed method. The proposed system will help the hospital authorities to identify severe and non-severe COVID-19 patients and adopt optimal treatment plans in pandemic situations.

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  • 4.
    Ahmed, Sheikh Ali
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Linnaeus University, Linnaeus Knowledge Environments, Advanced Materials.
    Adamopoulos, Stergios
    Swedish university of agricultural sciences, Sweden.
    Li, Junqiu
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Kovacikova, Janka
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Prediction of mechanical performance of acetylated MDF at different humid conditions2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 23, p. 1-16, article id 8712Article in journal (Refereed)
    Abstract [en]

    Change of relative humidity (RH) in surrounding environment can greatly affect the physical and mechanical properties of wood-based panels. Commercially produced acetylated medium density fiberboard (MDF), Medite Tricoya®, was used in this study to predict strength and stiffness under varying humid conditions by separating samples in parallel (//) and perpendicular (⊥) to the sanding directions. Thickness swelling, static moduli of elasticity (MOEstat) and rupture (MORstat), and internal bond (IB) strength were measured at three different humid conditions, i.e., dry (35% RH), standard (65% RH) and wet (85% RH). Internal bond (IB) strength was also measured after accelerated aging test. A resonance method was used to determine dynamic modulus of elasticity (MOEdyn) at the aforementioned humid conditions. Linear regression and finite element (FE) analyses were used to predict the MDF’s static bending behavior. Results showed that dimensional stability, MOEstat, MORstat and IB strength decreased significantly with an increase in RH. No reduction of IB strength was observed after 426 h of accelerated aging test. A multiple regression model was established using MOEdyn and RH values to predict MOEstat and MORstat. In both directions (// and ⊥), highly significant relationships were observed. The predicted and the measured values of MOEstat and MORstat were satisfactorily related to each other, which indicated that the developed model can be effectively used for evaluating the strength and stiffness of Medite Tricoya® MDF samples at any humid condition. Percent errors of two different simulation techniques (standard and extended FE method) showed highly efficient way of simulating the MDF structures with low fidelity.

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  • 5.
    Ahmed, Soban
    et al.
    Natl Univ Comp & Emerging Sci, PAK.
    Bhatti, Muhammad Tahir
    Natl Univ Comp & Emerging Sci, PAK.
    Khan, Muhammad Gufran
    Natl Univ Comp & Emerging Sci, PAK.
    Lövström, Benny
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Shahid, Muhammad
    Natl Univ Comp & Emerging Sci, PAK.
    Development and Optimization of Deep Learning Models for Weapon Detection in Surveillance Videos2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 12, article id 5772Article in journal (Refereed)
    Abstract [en]

    Featured Application This work has applied computer vision and deep learning technology to develop a real-time weapon detector system and tested it on different computing devices for large-scale deployment. Weapon detection in CCTV camera surveillance videos is a challenging task and its importance is increasing because of the availability and easy access of weapons in the market. This becomes a big problem when weapons go into the wrong hands and are often misused. Advances in computer vision and object detection are enabling us to detect weapons in live videos without human intervention and, in turn, intelligent decisions can be made to protect people from dangerous situations. In this article, we have developed and presented an improved real-time weapon detection system that shows a higher mean average precision (mAP) score and better inference time performance compared to the previously proposed approaches in the literature. Using a custom weapons dataset, we implemented a state-of-the-art Scaled-YOLOv4 model that resulted in a 92.1 mAP score and frames per second (FPS) of 85.7 on a high-performance GPU (RTX 2080TI). Furthermore, to achieve the benefits of lower latency, higher throughput, and improved privacy, we optimized our model for implementation on a popular edge-computing device (Jetson Nano GPU) with the TensorRT network optimizer. We have also performed a comparative analysis of the previous weapon detector with our presented model using different CPU and GPU machines that fulfill the purpose of this work, making the selection of model and computing device easier for the users for deployment in a real-time scenario. The analysis shows that our presented models result in improved mAP scores on high-performance GPUs (such as RTX 2080TI), as well as on low-cost edge computing GPUs (such as Jetson Nano) for weapon detection in live CCTV camera surveillance videos.

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  • 6.
    Ait-Mlouk, Addi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Alawadi, Sadi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Toor, Salman
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Hellander, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    FedQAS: Privacy-Aware Machine Reading Comprehension with Federated Learning2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 6, article id 3130Article in journal (Refereed)
    Abstract [en]

    Machine reading comprehension (MRC) of text data is a challenging task in Natural Language Processing (NLP), with a lot of ongoing research fueled by the release of the Stanford Question Answering Dataset (SQuAD) and Conversational Question Answering (CoQA). It is considered to be an effort to teach computers how to "understand" a text, and then to be able to answer questions about it using deep learning. However, until now, large-scale training on private text data and knowledge sharing has been missing for this NLP task. Hence, we present FedQAS, a privacy-preserving machine reading system capable of leveraging large-scale private data without the need to pool those datasets in a central location. The proposed approach combines transformer models and federated learning technologies. The system is developed using the FEDn framework and deployed as a proof-of-concept alliance initiative. FedQAS is flexible, language-agnostic, and allows intuitive participation and execution of local model training. In addition, we present the architecture and implementation of the system, as well as provide a reference evaluation based on the SQuAD dataset, to showcase how it overcomes data privacy issues and enables knowledge sharing between alliance members in a Federated learning setting.

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  • 7.
    Alex-Amor, Antonio
    et al.
    Univ Politecn Madrid, Informat Proc & Telecommun Ctr, E-28040 Madrid, Spain.;Univ Granada, Dept Teoria Senal Telemat & Comunicac, E-18071 Granada, Spain..
    Valerio, Guido
    Sorbonne Univ, CNRS, Lab Genie Elect & Elect Paris, F-75252 Paris, France.;Univ Paris Saclay, Cent Supelec, CNRS, Lab Genie Elect & Elect Paris, F-91192 Gif Sur Yvette, France..
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Mesa, Francisco
    Univ Seville, Microwaves Grp, Dept Appl Phys 1, Escuela Tecn Super Ingn Informat, E-41012 Seville, Spain..
    Padilla, Pablo
    Univ Granada, Dept Teoria Senal Telemat & Comunicac, E-18071 Granada, Spain..
    Fernandez-Gonzalez, Jose M.
    Univ Politecn Madrid, Informat Proc & Telecommun Ctr, E-28040 Madrid, Spain..
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Wave Propagation in Periodic Metallic Structures with Equilateral Triangular Holes2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 5, article id 1600Article in journal (Refereed)
    Abstract [en]

    This paper studies wave propagation in a periodic parallel-plate waveguide with equilateral triangular holes. A mode-matching method is implemented to analyze the dispersion diagram of the structure possessing glide and mirror symmetries. Both structures present an unexpected high degree of isotropy, despite the triangle not being symmetric with respect to rotations of 90 degrees. We give some physical insight on the matter by carrying out a modal decomposition of the total field on the hole and identifying the most significant modes. Additionally, we demonstrate that the electrical size of the triangular hole plays a fundamental role in the physical mechanism that causes that isotropic behavior. Finally, we characterize the influence of the different geometrical parameters that conform the unit cell (period, triangle size, hole depth, separation between metallic plates). The glide-symmetric configuration offers higher equivalent refractive indexes and widens the stopband compared to the mirror-symmetric configuration. We show that the stopband is wider as the triangle size is bigger, unlike holey structures composed of circular and elliptical holes where an optimal hole size exists.

  • 8.
    Alharbi, Abdullah G.
    et al.
    Jouf Univ, Fac Engn, Dept Elect Engn, Sakaka 42421, Saudi Arabia..
    Rafique, Umair
    Sapienza Univ Rome, Dept Informat Engn Elect & Telecommun, I-00184 Rome, Italy..
    Ullah, Shakir
    Univ Engn & Technol, Telecommun Engn Dept, Mardan 23200, Pakistan..
    Khan, Salahuddin
    King Saud Univ, Coll Engn, POB 800, Riyadh 11421, Saudi Arabia..
    Abbas, Syed Muzahir
    Macquarie Univ, Fac Sci & Engn, Sch Engn, Sydney, NSW 2109, Australia..
    Ali, Esraa Mousa
    Amman Arab Univ, Fac Aviat Sci, Amman 11953, Jordan..
    Alibakhshikenari, Mohammad
    Univ Carlos III Madrid, Dept Signal Theory & Commun, Madrid 28911, Spain..
    Dalarsson, Mariana
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering.
    Novel MIMO Antenna System for Ultra Wideband Applications2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 7, article id 3684Article in journal (Refereed)
    Abstract [en]

    The design of a 4 x 4 MIMO antenna for UWB communication systems is presented in this study. The single antenna element is comprised of a fractal circular ring structure backed by a modified partial ground plane having dimensions of 30 x 30 mm(2). The single antenna element has a wide impedance bandwidth of 9.33 GHz and operates from 2.67 GHz to 12 GHz. Furthermore, the gain of a single antenna element increases as the frequency increases, with a peak realized gain and antenna efficiency of 5 dBi and >75%, respectively. For MIMO applications, a 4 x 4 array is designed and analyzed. The antenna elements are positioned in a plus-shaped configuration to provide pattern as well as polarization diversity. It is worth mentioning that good isolation characteristics are achieved without the utilization of any isolation enhancement network. The proposed MIMO antenna was fabricated and tested, and the results show that it provides UWB response from 2.77 GHz to over 12 GHz. The isolation between the antenna elements is more than 15 dB. Based on performance attributes, it can be said that the proposed design is suitable for UWB MIMO applications.

  • 9. Ali, S.
    et al.
    Qureshi, S. S.
    Ali Hassan, S.
    Quaternion codes in MIMO systemof dual-polarized antennas2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 7, article id 3131Article in journal (Refereed)
    Abstract [en]

    The use of quaternion orthogonal designs (QODs) to describe point-to-point communication among dual-polarized antennas has the potential to provide higher rate orthogonal and quasi-orthogonal complex designs exploiting polarization diversity among space and time diversities. Furthermore, it is essential to have a space time block code (STBC) which offers a linear and decoupled decoder which quasi-orthogonal designs fail to attain. In this paper, we show how the realm of quaternions unexpectedly offers us a possible solution and codes obtained from quaternion designs mostly achieve both linear and decoupled decoders. This motivated us to perform an indispensable search for QODs such that the code rate is bounded below by 1/2 and does not sharply decrease as the number of transmit antennas increases. It is shown that three famous recursive techniques do not satisfy this criteria and their code rates decrease rather rapidly. Therefore, we propose another method of constructing quaternion designs suitable for any number of transmit antennas and verify that these attain linear and decoupled decoders with the system model based on quaternionic channel. It is shown that such designs outperform others in terms of transmit diversity, code rates and the optimality of the proposed decoder is validated through simulation results. © 2021 by the authors.

  • 10.
    Al-Jabban, Wathiq
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    A Comparative Evaluation of Cement and By-Product Petrit T in Soil Stabilization2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 23, article id 5238Article in journal (Refereed)
    Abstract [en]

    This study presents a comparison between the effectiveness of adding low binder amounts of industrial by-product Petrit T as well as cement to modify and improve fine-grained soil. Binder amount was added by soil dry weight; cement at 1%, 2%, 4% and 7% and Petrit T at 2%, 4% and 7%. The unconfined compressive strength (UCS) was used as an indicator of soil strength. In addition, the consistency limits, laser particle size analysis, and pH tests were also conducted on the treated soil. The samples were cured at 20 °C for different periods from 7 to 90 days before testing. Results indicate that cement is more effective at improving the physical and engineering properties of the treated soil. Soil plasticity index decreases after treatment and with time. Liquidity index and the water content to plastic limit ratio are introduced as new indices to define the improvement in the workability of treated soil. Soil particle size distribution is changed by reducing the clay size fraction and increasing the silt size fraction after treatment. The findings confirm that adding small binder contents improve soil properties, which subsequently reduce the environmental threats and costs that are associated with using a high amount of binder.

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  • 11.
    Al-Jabban, Wathiq
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. Engineering Dept., University of Babylon, Babylon, Iraq.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Effect of Disintegration Times of the Homogeneity of Soil prior to Treatment2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 22, article id 4791Article in journal (Refereed)
    Abstract [en]

    This paper presents an experimental study to investigate the effect of various disintegration times on the homogeneity of pre-treated natural soil before mixing with cementitious binders. Various disintegration times were applied, ranging from 10 s to 120 s. Four different soils were used with different characteristics from high, medium and low plasticity properties. Visual and sieving assessment were used to evaluate the best disintegration times to allow for a uniform distribution of water content and small-sized particles that would produce a uniform distribution of the binder around the soil particles. Results showed that a proper mixing time to homogenize and disintegrate the soil prior to treatment depended on several factors: soil type, water content and plasticity properties. For high plasticity soil, the disintegration time should be kept as short as possible. Increasing the disintegration time ha negative effects on the uniformity of distribution of the binder around soil particles. The homogenizing and disintegration time were less important for low plasticity soils with low water content than for medium to high plasticity soils. The findings could assist various construction projects that deal with soil improvement through preparation of soil before adding a cementitious binder to ensure uniformity of distribution of the binder around soil particles and obtain uniform soil–binder mixtures

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  • 12.
    Al-Janabi, Ahmed Mohammed Sami
    et al.
    Department of Civil Engineering, Faculty of Engineering, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia.
    Ghazali, Abdul Halim
    Department of Civil Engineering, Faculty of Engineering, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia.
    Yusuf, Badronnisa
    Department of Civil Engineering, Faculty of Engineering, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia.
    Sammen, Saad Sh.
    Department of Civil Engineering, College of Engineering, University of Diyala, Diyala Governorate, Iraq.
    Afan, Haitham Abdulmohsin
    Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Shahid, Shamsuddin
    School of Civil Engineering, Faculty of Engineering, Universiti Teknologi Malaysia (UTM), Johor Bahru 81310, Malaysia.
    Yaseen, Zaher Mundher
    Sustainable Developments in Civil Engineering Research Group, Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
    Optimizing Height and Spacing of Check Dam Systems for Better Grassed Channel Infiltration Capacity2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 11, article id 3725Article in journal (Refereed)
    Abstract [en]

    The check dams in grassed stormwater channels enhance infiltration capacity by temporarily blocking water flow. However, the design properties of check dams, such as their height and spacing, have a significant influence on the flow regime in grassed stormwater channels and thus channel infiltration capacity. In this study, a mass-balance method was applied to a grassed channel model to investigate the effects of height and spacing of check dams on channel infiltration capacity. Moreover, an empirical infiltration model was derived by improving the modified Kostiakov model for reliable estimation of infiltration capacity of a grassed stormwater channel due to check dams from four hydraulic parameters of channels, namely, the water level, channel base width, channel side slope, and flow velocity. The result revealed that channel infiltration was increased from 12% to 20% with the increase of check dam height from 10 to 20 cm. However, the infiltration was found to decrease from 20% to 19% when a 20 cm height check dam spacing was increased from 10 to 30 m. These results indicate the effectiveness of increasing height of check dams for maximizing the infiltration capacity of grassed stormwater channels and reduction of runoff volume.

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  • 13.
    Alonso-Rosa, Manuel
    et al.
    University of Cordoba.
    Gil-de-Castro, Aurora
    University of Cordoba.
    Moreno-Munoz, Antonio
    University of Cordoba.
    Garrido-Zafra, Joaquin
    University of Cordoba.
    Gutierrez-Ballesteros, Elena
    University of Cordoba.
    Cañete-Carmona, Eduardo
    University of Cordoba.
    An IoT based mobile augmented reality application for energy visualization in buildings environments2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 2, article id 600Article in journal (Refereed)
    Abstract [en]

    Augmented reality (AR) improves how we acquire, understand, and display information without distracting us from the real world. These technologies can be used in different applications and industries as they can incorporate domain-specific visualizations on a real-world screen. Mobile augmented reality (MAR) essentially consists of superimposing virtual elements over real objects on the screen, to give added value and enrich the interaction with reality. In numerous plants, it is being used for maintenance and repair tasks, as well as training. The Internet of Things (IoT) is increasingly pervading every aspect of our lives, including the power infrastructure of our buildings. IoT-enabled devices offer many connectivity options for helping supervise all-important energy assets. Aggregating data to cloud-based platforms enables operations teams to have on-time information access to make fast decisions and have a fast response regarding energy use, while maintenance teams keep on top of the appliance power quality and reliability needed by using MAR. This paper presents a novel approximation for visualizing appliance-related power quality to enhance awareness about the consumed electricity. A combined solution of MAR with IoT technologies is employed. Engineered solutions’ hands-free way to get data about surrounding appliances reduces the complexity, saves energy, and speeds up the operations. An innovative way to measure things at the right time leads to a competitive advantage.

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  • 14.
    Alsolai, Hadeel
    et al.
    Princess Nourah Bint Abdulrahman Univ, SAU.
    Qureshi, Shahnawaz
    Natl Univ Comp & Emerging Sci, PAK.
    Iqbal, Syed Muhammad Zeeshan
    BrightWare LLC, SAU.
    Ameer, Asif
    Natl Univ Comp & Emerging Sci, PAK.
    Cheaha, Dania
    Prince Songkla Univ, THA.
    Henesey, Lawrence
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science.
    Karrila, Seppo
    Prince Songkla Univ, THA.
    Employing a Long-Short-Term Memory Neural Network to Improve Automatic Sleep Stage Classification of Pharmaco-EEG Profiles2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 10, article id 5248Article in journal (Refereed)
    Abstract [en]

    An increasing problem in today's society is the spiraling number of people suffering from various sleep disorders. The research results presented in this paper support the use of a novel method that employs techniques from the classification of sleep disorders for more accurate scoring. Applying this novel method will assist researchers with better analyzing subject profiles for recommending prescriptions or to alleviate sleep disorders. In biomedical research, the use of animal models is required to experimentally test the safety and efficacy of a drug in the pre-clinical stage. We have developed a novel LSTM Recurrent Neural Network to process Pharmaco-EEG Profiles of rats to automatically score their sleep-wake stages. The results indicate improvements over the current methods; for the case of combined channels, the model accuracy improved by 1% and 3% in binary or multiclass classifications, respectively, to accuracies of 93% and 82%. In the case of using a single channel, binary and multiclass LSTM models for identifying rodent sleep stages using single or multiple electrode positions for binary or multiclass problems have not been evaluated in prior literature. The results reveal that single or combined channels, and binary or multiclass classification tasks, can be applied in the automatic sleep scoring of rodents.

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  • 15.
    Amini, Ata
    et al.
    Kurdistan Agricultural and Natural Resources Research and Education Center, AREEO, Sanandaj, Iran.
    Kolahchi, Abdolnabi Abdeh
    Soil Conservation and Watershed Management Research Institute, SCWMRI, AREEO, Tehran, Iran.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Moghadam, Mehdi Karami
    Department of Agriculture, Payame Noor University (PNU), Tehran, Iran.
    Mohammad, Thamer
    Department of Water Resources Engineering, College of Engineering, University of Baghdad, Baghdad, Iraq.
    Application of TRMM Precipitation Data to Evaluate Drought and Its Effects on Water Resources Instability2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 24, article id 5377Article in journal (Refereed)
    Abstract [en]

    The present research was carried out to study drought and its effects upon water resources using remote sensing data. To this end, the tropical rainfall measuring mission (TRMM) satellite precipitation, the synoptic stations, and fountain discharge data were employed. For monitoring of drought in the study area, in Kermanshah province, Iran, the monthly precipitation data of the synoptic stations along with TRMM satellite precipitation datasets were collected and processed in the geographic information system (GIS) environment. Statistical indicators were applied to evaluate the accuracy of TRMM precipitation against the meteorological stations’ data. Standardized precipitation index, SPI, and normalized fountain discharge were used in the monitoring of drought conditions, and fountains discharge, respectively. The fountains were selected so that in addition to enjoying the most discharge rates, they spread along the study area. The evaluation of precipitation data showed that the TRMM precipitation data were of high accuracy. Studies in temporal scale are indicative of the strike of drought in this region to the effect that for most months of the year, frequency and duration in dry periods are much more than in wet periods. As for seasonal scales, apart from winter, the frequency and duration of drought in spring and autumn have been longer than in wet years. Moreover, the duration of these periods was different. A comparison between the results of changes in fountain discharges and drought index in the region has verified that the drought has caused a remarkable decline in the fountain discharges.

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  • 16.
    Andersson, Anton
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Brander, Linus
    Division of Built Environment—Infrastructure and Concrete, Research Institute of Sweden, SE-501 15 Borås, Sweden.
    Lennartsson, Andreas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Roos, Ake
    Boliden AB, SE-101 20 Stockholm, Sweden.
    Engström, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    A Method for Synthesizing Iron Silicate Slags to Evaluate Their Performance as Supplementary Cementitious Materials2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 14, article id 8357Article in journal (Refereed)
    Abstract [en]

    Utilizing iron silicate copper slag as supplementary cementitious material (SCM) is a means to improve resource efficiency and lower the carbon dioxide emissions from cement production. Despite multiple studies on the performance of these slags in SCM applications, the variations in cooling procedure, grinding, and methods for evaluating reactivity limit the ability to assess the influence of chemical composition on reactivity from the literature data. In this study, a methodology was developed to synthesize iron silicate slags, which were then evaluated for their inherent reactivity using the R-3 calorimeter-based experiments. The results demonstrated that laboratory-scale granulation produced the same reactivity as industrially granulated slag. Furthermore, a synthesized triplicate sample showed high repeatability. Based on these two aspects, this method can be used to systematically study the influence of chemical composition on the inherent reactivity of iron silicate slags while producing results that are directly translatable to industrial slags.

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  • 17.
    Andersson, Anton
    et al.
    Luleå University of Technology, Sweden.
    Brander, Linus
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology.
    Lennartsson, Andreas
    Luleå University of Technology, Sweden.
    Roos, Åke
    Boliden AB, Sweden.
    Engström, Fredrik
    Luleå University of Technology, Sweden.
    A Method for Synthesizing Iron Silicate Slags to Evaluate Their Performance as Supplementary Cementitious Materials2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 14, article id 8357Article in journal (Refereed)
    Abstract [en]

    Utilizing iron silicate copper slag as supplementary cementitious material (SCM) is a means to improve resource efficiency and lower the carbon dioxide emissions from cement production. Despite multiple studies on the performance of these slags in SCM applications, the variations in cooling procedure, grinding, and methods for evaluating reactivity limit the ability to assess the influence of chemical composition on reactivity from the literature data. In this study, a methodology was developed to synthesize iron silicate slags, which were then evaluated for their inherent reactivity using the R3 calorimeter-based experiments. The results demonstrated that laboratory-scale granulation produced the same reactivity as industrially granulated slag. Furthermore, a synthesized triplicate sample showed high repeatability. Based on these two aspects, this method can be used to systematically study the influence of chemical composition on the inherent reactivity of iron silicate slags while producing results that are directly translatable to industrial slags. © 2023 by the authors.

  • 18.
    Andersson, Rabé
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    The Energy Consumption and Robust Case Torque Control of a Rehabilitation Hip Exoskeleton2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 21, article id 11104Article in journal (Refereed)
    Abstract [en]

    Gait disorders, muscle weakness, spinal cord injuries (SCIs) and other work-related disorders have increased the need for rehabilitation exoskeletons—specifically, for the hip because a huge percentage of mechanical power comes from the hip joint. However, realising a lightweight rehabilitation hip exoskeleton for mobility and at-home use with reliable control is challenging. The devices developed are restricted by a joint actuator and energy source design and tend to have various uncertainties. Thus, this study tested the robustness of four optimal controller cases in a simulation-based environment. We sought to determine whether the most robust optimal controller consumed less energy and demonstrated better performance in tracking the desired signal. The robustness of the optimal cases was tested with the hip torque signals of healthy subjects. The number of sit-to-stand (STS) instances and the walking distance at various speeds were calculated. The results showed that the most robust case controller was more energy efficient for STS, but not for walking activity. Furthermore, this study provides compelling evidence that various optimal controllers have different degrees of robustness and effects on energy consumption.

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  • 19.
    Andersson, Rachele
    et al.
    Lunds universitet.
    Jönsson, Peter
    Kristianstad University, Faculty of Education, Department of Psychology. Kristianstad University, Faculty of Natural Sciences, Research environment Man & Biosphere Health (MABH).
    Sandsten, Maria
    Lunds universitet.
    Stochastic modeling and optimal time-frequency estimation of task-related HRV2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 23, p. 1-16, article id 5154Article in journal (Refereed)
    Abstract [en]

    In this paper, we propose a novel framework for the analysis of task-related heart rate variability (HRV). Respiration and HRV are measured from 92 test participants while performing a chirp-breathing task consisting of breathing at a slowly increasing frequency under metronome guidance. A non-stationary stochastic model, belonging to the class of Locally Stationary Chirp Processes, is used to model the task-related HRV data, and its parameters are estimated with a novel inference method. The corresponding optimal mean-square error (MSE) time-frequency spectrum is derived and evaluated both with the individually estimated model parameters and the common process parameters. The results from the optimal spectrum are compared to the standard spectrogram with different window lengths and the Wigner-Ville spectrum, showing that the MSE optimal spectral estimator may be preferable to the other spectral estimates because of its optimal bias and variance properties. The estimated model parameters are considered as response variables in a regression analysis involving several physiological factors describing the test participants’ state of health, finding a correlation with gender, age, stress, and fitness. The proposed novel approach consisting of measuring HRV during a chirp-breathing task, a corresponding time-varying stochastic model, inference method, and optimal spectral estimator gives a complete framework for the study of task-related HRV in relation to factors describing both mental and physical health and may highlight otherwise overlooked correlations. This approach may be applied in general for the analysis of non-stationary data and especially in the case of task-related HRV, and it may be useful to search for physiological factors that determine individual differences.

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  • 20.
    Arena, Maurizio
    et al.
    Magnaghi Aeronaut MA Grp Co, Engn & Res Unit, Via Galileo Ferraris 76, I-80146 Naples, NA, Italy..
    Mehta, Bharat
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Properties. Chalmers Univ Technol, Dept Ind & Mat Sci, Rannvagen 2A, S-41296 Gothenburg, Sweden.
    Tirelli, Tommaso
    Aidro S r l, I-21020 Taino, VA, Italy..
    Ambrogiani, Paolo
    Aidro S r l, I-21020 Taino, VA, Italy..
    Castaldo, Martina
    Magnaghi Aeronaut MA Grp Co, Engn & Res Unit, Via Galileo Ferraris 76, I-80146 Naples, NA, Italy..
    Bengtsson, Sven
    Chalmers Univ Technol, Dept Ind & Mat Sci, Rannvagen 2A, S-41296 Gothenburg, Sweden.;Hoganas AB, Bruksgatan 35, SE-26383 Hoganas, Sweden..
    Nyborg, Lars
    Chalmers Univ Technol, Dept Ind & Mat Sci, Rannvagen 2A, S-41296 Gothenburg, Sweden..
    Novel Aluminum Alloy Tailored for Additive Manufacturing: Structural Characterization and Qualification Perspectives2024In: Applied Sciences, E-ISSN 2076-3417, Vol. 14, no 11, article id 4647Article in journal (Refereed)
    Abstract [en]

    Featured Application The paper demonstrates key structural characteristics of a novel aluminum alloy conceived for AM-based components in the aviation frame.Abstract The recent advances achieved in additive manufacturing (AM) technology demonstrate the potential to realize customized metal components, ensuring weight reduction opportunities. These benefits make AM attractive for high-cost aerospace applications, especially where high geometric complexity is required. In the context of an EU research scenario, the H2020 MANUELA (Additive Manufacturing Using Metal Pilot Line) project promotes the development of new technologies for design optimization by enabling the application of novel materials in AM. This paper illustrates recent advances in a new aluminum alloy (Al-HS1) with high strength emphasizing all of the characterization steps at the coupon level. This material has been employed in the re-engineering of a conventional hydraulic manifold using a powder bed fusion-laser beam (PBF-LB) process. Both the simulations and structural tests allowed for proving its compliance and technological maturity with industrial standards and applicable airworthiness requirements.

  • 21.
    Arnberg, Philip
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Petersson, Oscar Barreira
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Dahlberg, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Ghasemifard, Fatemeh
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electromagnetic Engineering.
    High Refractive Index Electromagnetic Devices in Printed Technology Based on Glide-Symmetric Periodic Structures2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 9, article id 3216Article in journal (Refereed)
    Abstract [en]

    We demonstrate the beneficial effects of introducing glide symmetry in a two-dimensional periodic structure. Specifically, we investigate dielectric parallel plate waveguides periodically loaded with Jerusalem cross slots in three configurations: conventional, mirror- and glide-symmetric. Out of these three configurations, it is demonstrated that the glide-symmetric structure is the least dispersive and has the most isotropic response. Furthermore, the glide-symmetric structure provides the highest effective refractive index, which enables the realization of a broader range of electromagnetic devices. To illustrate the potential of this glide-symmetric unit cell, a Maxwell fish-eye lens is designed to operate at 5 GHz. The lens is manufactured in printed circuit board technology. Simulations and measurements are in good agreement and a measured peak transmission coefficient of -0.5 dB is achieved.

  • 22.
    Arrhenius, Karine
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Bohlen, Haleh
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Büker, Oliver
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    de Krom, Iris
    VSL Dutch Metrology Institute, Netherlands.
    Heikens, Dita
    VSL Dutch Metrology Institute, Netherlands.
    van Wijk, Janneke
    VSL Dutch Metrology Institute, Netherlands.
    Hydrogen purity analysis: Suitability of sorbent tubes for trapping hydrocarbons, halogenated hydrocarbons and sulphur compounds2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 1, article id 120Article in journal (Refereed)
    Abstract [en]

    The ISO 14687-2 standard sets requirements for the purity of the hydrogen that is delivered at refuelling stations. These specifications cover a wide range of impurities and include challenging measurements, mainly due to the very low levels of the required detection limits and the need for "total" measurements (total hydrocarbons, total sulphur compounds, halogenated compounds). Most of the compounds belonging to the species are organic. Thermal desorption often coupled with gas chromatography is a common speciation method used to determine the content of organic impurities. However, no existing sorbent tubes are sufficiently universal to trap all possible impurities; depending on the sorbents and the sampling volume, some compounds may irreversibly adsorb or may break through. It is therefore necessary to evaluate sorbents for the compounds targeted at the level required. In this study, the suitability of sorbent tubes for trapping organic impurities in hydrogen was investigated. Suitable sorbents were selected based on a literature review of suitable sorbent materials. Short-term stability studies for compounds among hydrocarbons, halogenated compounds and sulphurcompounds on the selected sorbents have then been performed for storage periods of two weeks since this is the period typically required to complete the collection, transport and analysis of hydrogen samples. The study clearly shows that the method is promising for total species, even through the results show that not all of the compounds belonging to the three total species to be analysed when performing hydrogen purity analysis can be quantified on one unique sorbent. A multibed sorbent consisting of Tenax TA (weak), Carboxen 1003 (medium), Carbograph 1 (strong) is shown to be a versatile sorbent suitable for the three "total species"; only a few compounds from each family would need to be analysed using other analytical methods. This method proposed here for total species will not only provide a sum of concentrations, but also an identification of which compound(s) is/are actually present in the hydrogen.

  • 23.
    Arrhenius, Karine
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioscience and Materials, Chemistry and Materials.
    Fischer, Andreas
    RISE - Research Institutes of Sweden (2017-2019), Bioscience and Materials, Chemistry and Materials.
    Büker, Oliver
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Measurement Science and Technology.
    Methods for sampling biogas and biomethane on adsorbent tubes after collection in gas bags2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 6, article id 1171Article in journal (Refereed)
    Abstract [en]

    Biogas is a renewable energy source with many different production pathways and numerous excellent opportunities for use; for example, as vehicle fuel after upgrading (biomethane). Reliable analytical methodologies for assessing the quality of the gas are critical for ensuring that the gas can be used technically and safely. An essential part of any procedure aimed at determining the quality is the sampling and transfer to the laboratory. Sampling bags and sorbent tubes are widely used for collecting biogas. In this study, we have combined these two methods, i.e., sampling in a gas bag before subsequent sampling onto tubes in order to demonstrate that this alternative can help eliminate the disadvantages associated with the two methods whilst combining their advantages; with expected longer storage stability as well as easier sampling and transport. The results of the study show that two parameters need to be taken into account when transferring gas from a bag on to an adsorbent; the water content of the gas and the flow rate used during transfer of the gas on to the adsorbent. © 2019 by the authors.

  • 24.
    Arwin, Hans
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Schoeche, Stefan
    JA Woollam Co Inc, NE 68508 USA.
    Hilfiker, James
    JA Woollam Co Inc, NE 68508 USA.
    Hartveit, Mattias
    Univ Rochester, NY 14627 USA.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Juarez-Rivera, Olga Rubi
    Cinvestav Queretaro, Mexico.
    Mendoza-Galvan, Arturo
    Cinvestav Queretaro, Mexico.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Optical Chirality Determined from Mueller Matrices2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 15, article id 6742Article in journal (Refereed)
    Abstract [en]

    Featured Application The analysis of the transmission of Mueller matrices facilitates studies of optical activity in samples that also exhibit linear anisotropy and depolarization and may have a multilayered structure. Such studies are important for the development of applications in chiroptics. Optical chirality, in terms of circular birefringence and circular dichroism, is described by its electromagnetic and magnetoelectric material tensors, and the corresponding optical activity contributes to the Mueller matrix. Here, spectroscopic ellipsometry in the spectral range 210-1690 nm is used to address chiral phenomena by measuring Mueller matrices in transmission. Three approaches to determine chirality parameters are discussed. In the first approach, applicable in the absence of linear polarization effects, circular birefringence and circular dichroism are evaluated directly from elements of a Mueller matrix. In the second method, differential decomposition is employed, which allows for the unique separation of chirality parameters from linear anisotropic parameters as well as from depolarization provided that the sample is homogeneous along the optical path. Finally, electromagnetic modeling using the Tellegen constitutive relations is presented. The last method also allows structural effects to be included. The three methods to quantify optical chirality are demonstrated for selected materials, including sugar solutions, alpha-quartz, liquid crystals, beetle cuticle, and films of cellulose nanocrystals.

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  • 25.
    Autio, Hanna
    et al.
    Lund Univ, Div Engn Acoust, Box 118, S-22100 Lund, Sweden..
    Barbagallo, Mathias
    Lund Univ, Div Engn Acoust, Box 118, S-22100 Lund, Sweden.;Brekke & Strand Akust AB, Box 122, S-20121 Malmö, Sweden..
    Ask, Carolina
    Hagberg, Delphine Bard
    Lund Univ, Div Engn Acoust, Box 118, S-22100 Lund, Sweden..
    Lindqvist Sandgren, Eva
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Art History.
    Lagergren, Karin Strinnholm
    Linnus Univ, Dept Mus & Art, S-35195 Växjö, Sweden.;Leuven Univ, Alamire Fdn, B-3001 Leuven, Belgium..
    Historically Based Room Acoustic Analysis and Auralization of a Church in the 1470s2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 4, article id 1586Article in journal (Refereed)
    Abstract [en]

    Worship space acoustics have been established as an important part of a nation's cultural heritage and area of acoustic research, but more research is needed regarding the region of northern Europe. This paper describes the historical acoustics of an important abbey church in Sweden in the 1470s. A digital historical reconstruction is developed. Liturgical material specific to this location is recorded and auralized within the digital reconstruction, and a room acoustic analysis is performed. The analysis is guided by liturgical practices in the church and the monastic order connected to it. It is found that the historical sound field in the church is characterized by the existence of two distinct acoustical subspaces within it, each corresponding to a location dedicated to the daily services of the monastical congregations. The subspaces show significantly better acoustic conditions for liturgical activities compared to the nave, which is very reverberant under the conditions of daily services. Acoustic transmission from the two subspaces is limited, indicating that the monastic congregations were visually and acoustically separated from the visitors in the nave and each other.

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  • 26.
    Awad, Ali Ismail
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science. Faculty of Engineering, Al-Azhar University, Qena, Egypt. Centre for Security, Communications and Network Research, University of Plymouth, Plymouth, UK.
    Hassaballah, M.
    Department of Computer Science, Faculty of Computers and Information, South Valley University, Qena, Egypt.
    Bag-of-Visual-Words for Cattle Identification from Muzzle Print Images2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 22, article id 4914Article in journal (Refereed)
    Abstract [en]

    Cattle, buffalo and cow identification plays an influential role in cattle traceability from birth to slaughter, understanding disease trajectories and large-scale cattle ownership management. Muzzle print images are considered discriminating cattle biometric identifiers for biometric-based cattle identification and traceability. This paper presents an exploration of the performance of the bag-of-visual-words (BoVW) approach in cattle identification using local invariant features extracted from a database of muzzle print images. Two local invariant feature detectors—namely, speeded-up robust features (SURF) and maximally stable extremal regions (MSER)—are used as feature extraction engines in the BoVW model. The performance evaluation criteria include several factors, namely, the identification accuracy, processing time and the number of features. The experimental work measures the performance of the BoVW model under a variable number of input muzzle print images in the training, validation, and testing phases. The identification accuracy values when utilizing the SURF feature detector and descriptor were 75%, 83%, 91%, and 93% for when 30%, 45%, 60%, and 75% of the database was used in the training phase, respectively. However, using MSER as a points-of-interest detector combined with the SURF descriptor achieved accuracies of 52%, 60%, 67%, and 67%, respectively, when applying the same training sizes. The research findings have proven the feasibility of deploying the BoVW paradigm in cattle identification using local invariant features extracted from muzzle print images. 

  • 27.
    Balliu, Enkeleda
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Engholm, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Digonnet, Michel J. F.
    Coetzee, Riaan. S.
    Elgcrona, Gunnar
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Compact single-frequency mopa using a silica fiber highly doped with yb3+2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 21, article id 9951Article in journal (Refereed)
    Abstract [en]

    We report on a single-frequency fiber master oscillator power amplifier utilizing a polarization-maintaining step-index fiber with an Al/Ce/F core-glass composition doped with a very high Yb concentration (0.25 at.%). This design made it possible to use a very short fiber (~1 m) and to coil it in a tight radius (4 cm in the amplifier, while 2 cm gave similarly negligible bending loss) so that the packaged system is one of the most compact reported to date (~0.6 L). The use of a short fiber increased the threshold for stimulated Brillouin scattering well above 100 W while maintaining near-ideal beam quality. The fiber was pumped with a diode-pumped solid-state laser and cooled passively by spooling it on a grooved aluminum mandrel. The amplifier produced a strongly linearly polarized output at 1064 nm in the fundamental mode (M2 ≤ 1.2) with a 150 kHz linewidth and a power of 81.5 W for 107 W of launched pump power. No deleterious effects from the elevated thermal load were observed. The residual photodarkening loss resulting from the high Yb concentration, found to be small (~0.7 dB/m inferred at 1064 nm) with accelerated aging, reduced the output power by only ~20% after 150 h of operation. 

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  • 28.
    Balliu, Enkeleda
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Engholm, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Digonnet, Michel J. F.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Quasi‐cw pumping of a single‐frequency fiber amplifier for efficient shg in ppln crystals with reduced thermal load2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 1, article id 285Article in journal (Refereed)
    Abstract [en]

    Single‐frequency lasers are essential for high‐resolution spectroscopy and sensing applications as they combine high‐frequency stability with low noise and high output power stability. For many of these applications, there is increasing interest in power‐scaling single‐frequency sources, both in the near‐infrared and visible spectral range. We report the second‐harmonic generation of 670 μJ at 532 nm of a single‐frequency fiber amplifier signal operating in the quasi‐continuous‐wave mode in a 10‐mm periodically poled Mg‐doped lithium niobate (MgO:PPLN) crystal, while increasing compactness. To the best of our knowledge, this is the highest pulse energy generated in this crystal, which may find applications in the visible and UV such as remote Raman spectroscopy. 

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  • 29.
    Beckinghausen, Aubrey
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Ivan, Jean-Paul A.
    Örebro Univ, Sch Sci & Technol, S-70182 Örebro, Sweden..
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Analysis of Influencing Characteristics of Biochars for Ammonium Adsorption2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 19, article id 9487Article in journal (Refereed)
    Abstract [en]

    This article summarizes and performs a systematic analysis using experimental results from recent research on ammonium recovery from aqueous sources using biochar. Numerous studies have focused on using different materials to produce biochar adsorbents, and many have attempted to draw conclusions about the physical or chemical characteristics that dominate the adsorption to infer the mechanism. However, to date, there has not been statistical analysis performed on a large set of adsorption data and physical/chemical characteristics of chars to be able to draw conclusions about ammonium adsorption mechanisms. From this analysis, it was found that consistency in experimental methods and characteristic measurement reporting is lacking, and therefore it is difficult to perform metadata analysis and draw conclusions about ammonium adsorption on biochar. Among the important factors influencing ammonia recovery proposed in literature, the meta-analysis only strongly supports the effect of BET surface area and NH4+ concentration, with weaker support for the importance of cation exchange capacity and pyrolysis temperature. This suggests that standard procedures for biochar production, experiments and analysis of physical and chemical characteristics are needed to usefully compare results across different studies. Examples of the present difficulty in identifying trends across studies are shown by comparing clusters in the data identified by the analysis. The ability to make such comparisons would provide clearer direction in how best to further improve the adsorption capacity of biochars.

  • 30.
    Bedon, Chiara
    et al.
    University of Trieste, Italy.
    Stochino, Flavio
    University of Cagliari, Italy.
    Honfi, Daniel
    RISE Research Institutes of Sweden.
    Special issue on "buildings and structures under extreme loads"2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 16, article id 5676Article in journal (Refereed)
    Abstract [en]

    Exceptional loads on buildings and structures may have different causes, including high-strain dynamic effects due to natural hazards, man-made attacks, and accidents, as well as extreme operational conditions (severe temperature variations, humidity, etc.). All these aspects can be critical for specific structural typologies and/or materials that are particularly sensitive to unfavorable external conditions. In this regard, dedicated and refined methods are required for their design, analysis, and maintenance under the expected lifetime. However, major challenges are usually related to the structural typology and materials object of study, with respect to the key features of the imposed design loads. Further issues can be derived from the need for the mitigation of adverse effects or retrofit of existing structures, as well as from the optimal and safe design of innovative materials/systems. Finally, in some cases, no appropriate design recommendations are currently available in support of practitioners, and thus experimental investigations (both on-site or on laboratory prototypes) can have a key role within the overall structural design and assessment process. This Special Issue presents 19 original research studies and two review papers dealing with the structural performance of buildings and structures under exceptional loads, and can represent a useful answer to the above-mentioned problems.

  • 31.
    Belay, Birhanu
    et al.
    Department of Computer Science, University of Kaiserslautern, Germany; Faculty of Computing, Bahir Dar Institute of Technology, Ethiopia.
    Habtegebrial, Tewodros
    Department of Computer Science, University of Kaiserslautern, Germany.
    Meshesha, Million
    School of Information Science, Addis Ababa University, Ethiopia.
    Liwicki, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Belay, Gebeyehu
    Faculty of Computing, Bahir Dar Institute of Technology, Ethiopia.
    Stricker, Didier
    Department of Computer Science, University of Kaiserslautern, Germany; German Research Center for Artificial Intelligence, DFKI, Germany.
    Amharic OCR: An End-to-End Learning2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 3, article id 1117Article in journal (Refereed)
    Abstract [en]

    In this paper, we introduce an end-to-end Amharic text-line image recognition approach based on recurrent neural networks. Amharic is an indigenous Ethiopic script which follows a unique syllabic writing system adopted from an ancient Geez script. This script uses 34 consonant characters with the seven vowel variants of each (called basic characters) and other labialized characters derived by adding diacritical marks and/or removing parts of the basic characters. These associated diacritics on basic characters are relatively smaller in size, visually similar, and challenging to distinguish from the derived characters. Motivated by the recent success of end-to-end learning in pattern recognition, we propose a model which integrates a feature extractor, sequence learner, and transcriber in a unified module and then trained in an end-to-end fashion. The experimental results, on a printed and synthetic benchmark Amharic Optical Character Recognition (OCR) database called ADOCR, demonstrated that the proposed model outperforms state-of-the-art methods by 6.98% and 1.05%, respectively.

  • 32.
    Benti, Gudeta Berhanu
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Aidanpää, Jan-Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Gustavsson, Rolf
    Vattenfall AB Research and Development, 814 26 Älvkarleby, Sweden.
    Cost-Effective Design Modification of a Sleeve Bearing with Large Bearing Clearance2024In: Applied Sciences, E-ISSN 2076-3417, Vol. 14, no 3, article id 1214Article in journal (Refereed)
    Abstract [en]

    In 2015, a 45 MW vertical hydropower machine exhibited excessive vibration after refurbishment. Measurements revealed a substantial bearing clearance at the lower generator guide bearing. Consequently, the bearing was unable to generate sufficient opposing force to drive the rotor toward the bearing center, resulting in more pronounced overall system vibration. Addressing this challenge required a cost-effective and feasible solution for mitigating the vibration problem. To this end, a design modification was implemented wherein the lower generator guide bearing (originally a sleeve bearing) was modified to a four-lobe bearing by offsetting the two halves of the bearing twice in two axes. Numerical simulations and experimentations were conducted, and the dynamics of the machine before and after the design modification were investigated. Both the simulation and experimental results showed that the machine with the four-lobe bearing improved the system stability and reduced the vibration amplitudes. The numerical simulation result demonstrated that, due to the design modification, the first and second critical speeds were effectively eliminated for a speed range of up to three times the nominal speed. Furthermore, for nominal operation with unbalanced magnetic pull, the four-lobe bearing provided a stability advantage in terms of the modal parameters relative to the original sleeve bearing.

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  • 33.
    Bhatti, A.
    et al.
    School of Electrical Engineering and Computer Science, National University of Sciences and Technology, Islamabad, 24090, Pakistan.
    Arif, A.
    School of Electrical Engineering and Computer Science, National University of Sciences and Technology, Islamabad, 24090, Pakistan.
    Khalid, W.
    Computer Engineering Department, Bahria University, Islamabad, 44000, Pakistan.
    Khan, B.
    Department of Electrical and Computer Engineering, International Islamic University, Islamabad, 04436, Pakistan.
    Ali, A.
    Department of Software Engineering, Bahria University, Islamabad, 44000, Pakistan.
    Khalid, S.
    Computer Engineering Department, Bahria University, Islamabad, 44000, Pakistan.
    Rehman, Atiq Ur
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Recognition and Classification of Handwritten Urdu Numerals Using Deep Learning Techniques2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 3, article id 1624Article in journal (Refereed)
    Abstract [en]

    Urdu is a complex language as it is an amalgam of many South Asian and East Asian languages; hence, its character recognition is a huge and difficult task. It is a bidirectional language with its numerals written from left to right while script is written in opposite direction which induces complexities in the recognition process. This paper presents the recognition and classification of a novel Urdu numeral dataset using convolutional neural network (CNN) and its variants. We propose custom CNN model to extract features which are used by Softmax activation function and support vector machine (SVM) classifier. We compare it with GoogLeNet and the residual network (ResNet) in terms of performance. Our proposed CNN gives an accuracy of 98.41% with the Softmax classifier and 99.0% with the SVM classifier. For GoogLeNet, we achieve an accuracy of 95.61% and 96.4% on ResNet. Moreover, we develop datasets for handwritten Urdu numbers and numbers of Pakistani currency to incorporate real-life problems. Our models achieve best accuracies as compared to previous models in the literature for optical character recognition (OCR).

  • 34.
    Bjurström, Johan
    et al.
    RISE Research Institutes of Sweden AB, Gothenburg, Sweden; Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, Sweden.
    Ohlsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. RISE Research Institutes of Sweden AB, Gothenburg, Sweden.
    Rusu, Cristina
    RISE Research Institutes of Sweden AB, Gothenburg, Sweden.
    Johansson, Christer
    RISE Research Institutes of Sweden AB, Gothenburg, Sweden; Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, Sweden.
    Unified modeling and analysis of vibration energy harvesters under inertial loads and prescribed displacements2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 19, article id 9815Article in journal (Refereed)
    Abstract [en]

    In this paper, we extend the optimization analysis found in the current literature for single-degree-of-freedom vibrational energy harvesters. We numerically derive and analyze the optimization conditions based on unified expressions for piezoelectric and electromagnetic energy harvesters. Our contribution lies in the detailed analysis and comparison of both resonant and anti-resonant states while fully including the effect of intrinsic resistance. We include both the case of excitation by inertial load and prescribed displacement, as the latter has not been elaborated on in the previous literature and provides new insights. We perform a general analysis but also consider typical values of applied piezoelectric and electromagnetic energy harvesters. Our results improve upon previous similar comparative studies by providing new and useful insights regarding optimal load, load power and power input to output efficiency. Our analysis shows an exponential increase in the critical mechanical quality factor due to the resistive loss coefficient. We find that the ratio of mechanical quality factor to resistive loss coefficient, at resonance, increases drastically close to the theoretical maximum for load power. Under the same optimization conditions, an equivalent conclusion can be drawn regarding efficiency. We find that the efficiency at anti-resonance behaves differently and is equal to or larger than the efficiency at resonance. We also show that the optimal load coefficient at resonance has a significant dependence on the mechanical quality factor only when the resistive loss coefficient is large. Our comparison of excitation types supports the previous literature, in a simple and intuitive way, regarding optimal load by impedance matching and power output efficiency. Our modeling and exploration of new parameter spaces provide an improved tool to aid the development of new harvester prototypes.

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  • 35.
    Björling, Marcus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Bair, Scott
    Georgia Institute of Technology, Centre for High Pressure Rheology, G.W. Woodruff School of Mechanical Engineering, Atlanta, GA.
    Mu, Liwen
    Intelligent Composites Laboratory, Department of Chemical and Biomolecular Engineering, The University of Akron.
    Zhu, Jiahua
    Intelligent Composites Laboratory, Department of Chemical and Biomolecular Engineering, The University of Akron.
    Shi, Yijun
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Elastohydrodynamic performance of a bio-based, non-corrosive ionic liquid2017In: Applied Sciences, E-ISSN 2076-3417, Vol. 17, no 10, article id 996Article in journal (Refereed)
    Abstract [en]

    To improve performance of machine components, lubrication is one of the most important factors. Especially for use in extreme environments, researchers look for other solutions rather than common lubricant base stocks like mineral oils or vegetable oils. One such example is ionic liquids. Ionic liquids have been defined as molten salts with melting points below 100 °C that are entirely ionic in nature, comprising both cationic and anionic species. The industrial use of ionic liquids is mostly as solvents, electrolytes, extractants and catalysts. In tribological applications, ionic liquids are mainly studied in boundary lubrication and in pure sliding contacts. In this work, the elastohydrodynamic performance of a bio-based, non-corrosive, [choline][L-proline] ionic liquid is evaluated in terms of pressure-viscosity response, film forming capability and friction. The results show a pressure-viscosity coefficient of below 8 GPa-1 at 25 °C, among the lowest reported for any ionic liquid. The ionic liquid generated up to 70% lower friction than a reference paraffin oil with a calculated difference in film thickness of 11%. It was also shown that this ionic liquid is very hygroscopic, which is believed to explain part of the low friction results, but also has to be considered in practical applications since the water content will influence the properties and thus the performance of the lubricant.

  • 36.
    Blachucki, Wojciech
    et al.
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Kayser, Yves
    Phys Tech Bundesanstalt, Abbestr 2-12, D-10587 Berlin, Germany..
    Wach, Anna
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Fanselow, Rafal
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Milne, Christopher
    European XFEL GmbH, D-22869 Schenefeld, Germany..
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Szlachetko, Jakub
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Resonant X-ray Emission Spectroscopy with a SASE Beam2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 18, article id 8775Article in journal (Refereed)
    Abstract [en]

    Featured Application In the present work, RXES planes are reconstructed with high energy resolution from the experimental spectra of the X-ray radiation emitted from a sample and of incident X-ray pulses delivered by an XFEL operated in the raw SASE mode. The dependence of the reconstructed RXES planes' quality on the number of recorded XFEL shots is studied. Aqueous iron (III) oxide nanoparticles were irradiated with pure self-amplified spontaneous emission (SASE) X-ray free-electron laser (XFEL) pulses tuned to the energy around the Fe K-edge ionization threshold. For each XFEL shot, the incident X-ray pulse spectrum and Fe K beta emission spectrum were measured synchronously with dedicated spectrometers and processed through a reconstruction algorithm allowing for the determination of Fe K beta resonant X-ray emission spectroscopy (RXES) plane with high energy resolution. The influence of the number of X-ray shots employed in the experiment on the reconstructed data quality was evaluated, enabling the determination of thresholds for good data acquisition and experimental times essential for practical usage of scarce XFEL beam times.

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  • 37.
    Blachucki, Wojciech
    et al.
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Wach, Anna
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Czapla-Masztafiak, Joanna
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Delcey, Mickael
    KTH Royal Inst Technol, Dept Theoret Chem & Biol, S-10691 Stockholm, Sweden..
    Arrell, Christopher
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Fanselow, Rafal
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Juranic, Pavle
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Lundberg, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Milne, Christopher
    European XFEL GmbH, D-22869 Schenefeld, Germany..
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, PL-01224 Warsaw, Poland..
    Szlachetko, Jakub
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Approaching the Attosecond Frontier of Dynamics in Matter with the Concept of X-ray Chronoscopy2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 3, article id 1721Article in journal (Refereed)
    Abstract [en]

    Featured Application Herein, an innovative methodology, called X-ray chronoscopy, is proposed for exploration of ultrafast processes in matter with attosecond precision using current XFEL sources. The method is based on measuring the change in an X-ray pulse temporal profile induced by interaction with a medium. X-ray free electron lasers (XFELs) have provided scientists opportunities to study matter with unprecedented temporal and spatial resolutions. However, access to the attosecond domain (i.e., below 1 femtosecond) remains elusive. Herein, a time-dependent experimental concept is theorized, allowing us to track ultrafast processes in matter with sub-fs resolution. The proposed X-ray chronoscopy approach exploits the state-of-the-art developments in terahertz streaking to measure the time structure of X-ray pulses with ultrahigh temporal resolution. The sub-femtosecond dynamics of the saturable X-ray absorption process is simulated. The employed rate equation model confirms that the X-ray-induced mechanisms leading to X-ray transparency can be probed via measurement of an X-ray pulse time structure.

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  • 38.
    Blachucki, Wojciech
    et al.
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Wach, Anna
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Czapla-Masztafiak, Joanna
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Delcey, Mickael G
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Arrell, Christopher
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Fanselow, Rafal
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Juranic, Pavle
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Lundberg, Marcus
    Uppsala Univ, Dept Chem, S-75120 Uppsala, Sweden..
    Milne, Christopher
    European XFEL GmbH, D-22869 Schenefeld, Germany..
    Sa, Jacinto
    Uppsala Univ, Dept Chem, S-75120 Uppsala, Sweden.;Polish Acad Sci, Inst Phys Chem, PL-01224 Warsaw, Poland..
    Szlachetko, Jakub
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Approaching the Attosecond Frontier of Dynamics in Matter with the Concept of X-ray Chronoscopy2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 3, article id 1721Article in journal (Refereed)
    Abstract [en]

    Featured Application Herein, an innovative methodology, called X-ray chronoscopy, is proposed for exploration of ultrafast processes in matter with attosecond precision using current XFEL sources. The method is based on measuring the change in an X-ray pulse temporal profile induced by interaction with a medium. X-ray free electron lasers (XFELs) have provided scientists opportunities to study matter with unprecedented temporal and spatial resolutions. However, access to the attosecond domain (i.e., below 1 femtosecond) remains elusive. Herein, a time-dependent experimental concept is theorized, allowing us to track ultrafast processes in matter with sub-fs resolution. The proposed X-ray chronoscopy approach exploits the state-of-the-art developments in terahertz streaking to measure the time structure of X-ray pulses with ultrahigh temporal resolution. The sub-femtosecond dynamics of the saturable X-ray absorption process is simulated. The employed rate equation model confirms that the X-ray-induced mechanisms leading to X-ray transparency can be probed via measurement of an X-ray pulse time structure.

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  • 39.
    Bobyr, Serhii
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures. Iron and Steel Institute of Z. I. Nekrasov, National Academy of Sciences of Ukraine, 49107 Dnipro, Ukraine.
    Krot, Pavlo
    Faculty of Geoengineering, Mining and Geology, Wroclaw University of Science and Technology, Wrocław, 50-370, Poland.
    Parusov, Eduard
    Iron and Steel Institute of Z. I. Nekrasov, National Academy of Sciences of Ukraine, 49107 Dnipro, Ukraine;.
    Golubenko, Tetiana
    Iron and Steel Institute of Z. I. Nekrasov, National Academy of Sciences of Ukraine, 49107 Dnipro, Ukraine;.
    Baranovs’ka, Olena
    Iron and Steel Institute of Z. I. Nekrasov, National Academy of Sciences of Ukraine, 49107 Dnipro, Ukraine;.
    Increasing the Wear Resistance of Structural Alloy Steel 38CrNi3MoV Subjected to Isothermal Hardening and Deep Cryogenic Treatment2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 16, article id 9143Article in journal (Refereed)
    Abstract [en]

    In the production of critical parts for various machines and mechanisms, expensive structural steels are used alloyed with chromium, nickel, molybdenum, and vanadium. In practice, the wear resistance of parts, especially under severe operating conditions, may be insufficient due to uneven microstructure and the content of retained austenite. Therefore, increasing the operational stability of various products made of alloy steels is an important task. The purpose of this work is to investigate the effect of isothermal hardening from the intermediate (γ+α)-area and the duration of deep cryogenic treatment on the structure formation and frictional wear resistance of 38CrNi3MoV steel. The isothermal hardening promotes the formation of the required multiphase microstructure of 38CrNi3MoV steel. The influence of the duration of deep cryogenic treatment on the microhardness, amount of retained austenite, fine structure parameters, and friction wear of 38CrNi3MoV steel are established. Complex heat treatment of 38CrNi3MoV steel, according to the proposed mode, makes it possible to achieve a significant decomposition of retained austenite to martensite, which leads to an increase in frictional wear resistance of ~58%.

  • 40.
    Broz, Jiri
    et al.
    Czech Tech Univ, Czech Republic.
    Tichy, Tomas
    Czech Tech Univ, Czech Republic.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Belinova, Zuzana
    Czech Tech Univ, Czech Republic.
    Usage of V2X Applications in Road Tunnels2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 9, article id 4624Article in journal (Refereed)
    Abstract [en]

    Featured Application This article provides a general overview of technological aspects and limitations of tunnels with respect to smart technologies such as C-ITS. Many smart city applications work with calculated position and time using the Global Navigation Satellite System (GNSS) signals for enhanced precision. However, there are many places where the availability of GNSS is limited, e.g., road tunnels, which are an essential part of transport infrastructure. Tunnels also require greater attention and greater importance of approaches to ensure the safety and security aspects of traffic. The safety, distribution of information, awareness, and smooth traffic can also be ensured by V2X applications, but the current position is also needed. An experimental analysis of data connection and communication availability was performed in the Blanka tunnel (Prague) and its surroundings. The main objective of the work was to find and clearly describe the tunnel blind spots, with an emphasis on communication between cars and potentially between cars and infrastructure. This article summarizes the evaluation results of the V2X tunnel experimental test, the outputs from the analysis of these blind spots, and it provides a future perspective and suggestions that make tunnels smart by using advanced positioning approaches.

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  • 41.
    Büker, Oliver
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Stolt, Krister
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    RISE Test Facilities for the Measurement of Ultra-Low Flow Rates and Volumes with a Focus on Medical Applications2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 16, article id 8332Article in journal (Refereed)
    Abstract [en]

    In the framework of the ongoing EMPIR JRP 18HLT08 Metrology for Drug Delivery (MeDDII), a main task is to improve dosing accuracy and enable traceable measurements of volume, flow and pressure of existing drug delivery devices and in-line sensors operating, in some cases, at ultra-low flow rates. This can be achieved by developing new calibration methods and by expanding existing metrological infrastructure. The MeDDII project includes, among other issues, investigations on fast changing flow rates, physical properties of liquid mixtures and occlusion phenomena to avoid inaccurate measurement results and thus improve patient safety. This paper describes the extension of an existing measurement facility at RISE and the design and construction of a new measurement facility to be able to carry out such investigations. The new measurement facility, which is based on the dynamic gravimetric method, is unique worldwide in respect of the lowest measurable flow rate. The gravimetric measuring principle is pushed to the limits of what is feasible. Here, the smallest changes in the ambient conditions have a large influence on the measurement accuracy. The new infrastructure can be used to develop and validate novel calibration procedures for existing drug delivery devices over a wide flow rate range. The extension of the measurement facilities also enables inline measurement of the pressure and the dynamic viscosity of Newtonian liquids. For this purpose, it is ensured that all measurements are traceable to primary standards. © 2022 by the authors.

  • 42. Cacciapuoti, S.
    et al.
    Di Leo, G.
    Ferro, M.
    Liguori, Consolatina
    University of Salerno, Fisciano, SA, Italy.
    Masarà, A.
    Scalvenzi, M.
    Sommella, P.
    Fabbrocini, G.
    A measurement software for professional training in early detection of melanoma2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 12, article id 4351Article in journal (Refereed)
    Abstract [en]

    Software systems have been long introduced as support to the early detection of melanoma through the automatic analysis of suspicious skin lesions. Nevertheless, their behavior is not yet similar to the performance exhibited by expert dermatologists in terms of diagnostic accuracy. Instead, a software system should be adopted by non-experienced dermatologists in order to improve the measurement and detection results for skin atypical patterns and the accuracy of the corresponding second opinion. This paper describes an image-based measurement and classification system able to score pigmented skin lesions according to the Seven-Point Check-list diagnostic method. Focus is devoted to the measurement procedure of biological structures more closely related to the atypical character of the nevus. Moreover, the performances of the measurement system are evaluated by considering the support to dermatologists with different experiences during the clinical activity. © 2020 by the authors.

  • 43.
    Caramaschi, Sara
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Computer Science and Media Technology (DVMT). Malmö University, Internet of Things and People (IOTAP). Department of Electronics, Information and Bioengineering, Politecnico di Milano, 20133 Milan, Italy.
    Papini, Gabriele B.
    Department of Patient Care & Monitoring, Philips Research, 5656 AE Eindhoven, The Netherlands;Department of Electrical Engineering, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands.
    Caiani, Enrico G.
    Department of Electronics, Information and Bioengineering, Politecnico di Milano, 20133 Milan, Italy;Istituto Auxologico Italiano, IRCCS, S. Luca Hospital, 20149 Milan, Italy.
    Device Orientation Independent Human Activity Recognition Model for Patient Monitoring Based on Triaxial Acceleration2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 7, p. 4175-4175Article in journal (Refereed)
    Abstract [en]

    Tracking a person’s activities is relevant in a variety of contexts, from health and group-specific assessments, such as elderly care, to fitness tracking and human–computer interaction. In a clinical context, sensor-based activity tracking could help monitor patients’ progress or deterioration during their hospitalization time. However, during routine hospital care, devices could face displacements in their position and orientation caused by incorrect device application, patients’ physical peculiarities, or patients’ day-to-day free movement. These aspects can significantly reduce algorithms’ performances. In this work, we investigated how shifts in orientation could impact Human Activity Recognition (HAR) classification. To reach this purpose, we propose an HAR model based on a single three-axis accelerometer that can be located anywhere on the participant’s trunk, capable of recognizing activities from multiple movement patterns, and, thanks to data augmentation, can deal with device displacement. Developed models were trained and validated using acceleration measurements acquired in fifteen participants, and tested on twenty-four participants, of which twenty were from a different study protocol for external validation. The obtained results highlight the impact of changes in device orientation on a HAR algorithm and the potential of simple wearable sensor data augmentation for tackling this challenge. When applying small rotations (<20 degrees), the error of the baseline non-augmented model steeply increased. On the contrary, even when considering rotations ranging from 0 to 180 along the frontal axis, our model reached a f1-score of 0.85±0.110.85±0.11 against a baseline model f1-score equal to 0.49±0.120.49±0.12.

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  • 44.
    Casadei, Roberto
    et al.
    Alma Mater Studiorum-Università di Bologna, Italy.
    Pianini, Danilo
    Alma Mater Studiorum-Università di Bologna, Italy.
    Viroli, Mirko
    Alma Mater Studiorum-Università di Bologna, Italy.
    Weyns, Danny
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM). Katholieke Universiteit Leuven, Belgium.
    Digital Twins, Virtual Devices, and Augmentations for Self-Organising Cyber-Physical Collectives2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 1, article id 349Article in journal (Refereed)
    Abstract [en]

    Simple Summary The engineering of self-organising cyber-physical systems can benefit from a variety of "logical devices", including digital twins, virtual devices, and (augmented) collective digital twins. In particular, collective digital twins provide for a design construct towards collective computing, which can be augmented with virtual devices to improve the performance of existing self-organising applications-as shown through swarm exploration and navigation scenarios. The engineering of large-scale cyber-physical systems (CPS) increasingly relies on principles from self-organisation and collective computing, enabling these systems to cooperate and adapt in dynamic environments. CPS engineering also often leverages digital twins that provide synchronised logical counterparts of physical entities. In contrast, sensor networks rely on the different but related concept of virtual device that provides an abstraction of a group of sensors. In this work, we study how such concepts can contribute to the engineering of self-organising CPSs. To that end, we analyse the concepts and devise modelling constructs, distinguishing between identity correspondence and execution relationships. Based on this analysis, we then contribute to the novel concept of "collective digital twin" (CDT) that captures the logical counterpart of a collection of physical devices. A CDT can also be "augmented" with purely virtual devices, which may be exploited to steer the self-organisation process of the CDT and its physical counterpart. We underpin the novel concept with experiments in the context of the pulverisation framework of aggregate computing, showing how augmented CDTs provide a holistic, modular, and cyber-physically integrated system view that can foster the engineering of self-organising CPSs.

  • 45.
    Cha, Kyeong-Ju
    et al.
    Korea Univ, Dept Electromech Engn, Sejong Si 30019, South Korea..
    Lee, Jung-Bum
    Korea Univ, Dept Electromech Engn, Sejong Si 30019, South Korea..
    Özger, Mustafa
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS.
    Lee, Woong-Hee
    Korea Univ, Dept Control & Instrumentat Engn, Sejong Si 30019, South Korea..
    When Wireless Localization Meets Artificial Intelligence: Basics, Challenges, Synergies, and Prospects2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 23, article id 12734Article, review/survey (Refereed)
    Abstract [en]

    The rapid development of information communication and artificial intelligence (AI) technology is driving innovation in various new application fields such as autonomous driving, augmented reality, and the metaverse. In particular, the advancement of wireless localization technology plays a great role in these cutting-edge technologies. However, traditional wireless localization systems rely on the global navigation satellite system (GNSS), which is ineffective in indoor or underground environments. To overcome this issue, indoor positioning systems (IPS) have gained attention, and various localization techniques utilizing wireless communication were studied. Subsequently, AI technologies are improving the performance of wireless localization and addressing problems that were previously difficult to solve. In this paper, we summarize wireless localization techniques and define the factors that impede their performance. Furthermore, we categorize AI algorithms and present examples of how they can be used to address these hindering factors. Finally, we propose open research directions and prospects for AI-assisted wireless localization.

  • 46.
    Chandran, Praneeth
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Thiery, Florian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Odelius, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Famurewa, Stephen Mayowa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lind, Håkan
    Bombardier Transport, 11743 Stockholm, Sweden.
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Supervised Machine Learning Approach for Detecting Missing Clamps in Rail Fastening System from Differential Eddy Current Measurements2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 9, article id 4018Article in journal (Refereed)
    Abstract [en]

    The rail fastening system forms an integral part of rail tracks, as it maintains the rail in a fixed position, upholding the track stability and track gauge. Hence, it becomes necessary to monitor their conditions periodically to ensure safe and reliable operation of the railway. Inspection is normally carried out manually by trained operators or by employing 2-D visual inspection methods. However, these methods have drawbacks when visibility is minimal and are found to be expensive and time consuming. In the previous study, the authors proposed a train-based differential eddy current sensor system that uses the principle of electromagnetic induction for inspecting the railway fastening system that can overcome the above-mentioned challenges. The sensor system includes two individual differential eddy current sensors with a driving field frequency of 18 kHz and 27 kHz respectively. This study analyses the performance of a machine learning algorithm for detecting and analysing missing clamps within the fastening system, measured using a train-based differential eddy current sensor. The data required for the study was collected from field measurements carried out along a heavy haul railway line in the north of Sweden, using the train-based differential eddy current sensor system. Six classification algorithms are tested in this study and the best performing model achieved a precision and recall of 96.64% and 95.52% respectively. The results from the study shows that the performance of the machine learning algorithms improved when features from both the driving channels were used simultaneously to represent the fasteners. The best performing algorithm also maintained a good balance between the precision and recall scores during the test stage.

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  • 47.
    Chen, DeJiu
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Su, Peng
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Ottikkutti, Suranjan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Embedded Control Systems.
    Vartholomeos, Panagiotis
    Tahmasebi, Kaveh Nazem
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Embedded Control Systems.
    Karamousadakis, Michalis
    Analyzing Dynamic Operational Conditions of Limb Prosthetic Sockets with a Mechatronics-Twin Framework2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 3, p. 986-986Article in journal (Refereed)
    Abstract [en]

    Lower limb prostheses offer a solution to restore the ambulation and self-esteem of amputees. One key component is the prosthetic socket that serves as the interface between prosthetic device and amputee stump and thereby has a wide range of impacts on efficient fitting, appropriate load transmission, operational stability, and control. For the design and optimization of a prosthetic socket, an understanding of the actual intra-socket operational conditions becomes therefore necessary. This is however a difficult task due to the inherent complexity and restricted observability of socket operation. In this study, an innovative mechatronics-twin framework that integrates advanced biomechanical models and simulations with physical prototyping and dynamic operation testing for effective exploration of operational behaviors of prosthetic sockets with amputees is proposed. Within this framework, a specific Stewart manipulator is developed to enable dynamic operation testing, in particular for a well-managed generation of dynamic intra-socket loads and behaviors that are otherwise difficult to observe or realize with the real amputees. A combination of deep learning and Bayesian Inference algorithms is then employed for analyzing the intra-socket load conditions and revealing possible anomalous. 

  • 48.
    Chen, Dingfu
    et al.
    Shanghai Univ, Peoples R China.
    Peng, Junzheng
    Jinan Univ, Peoples R China.
    Valyukh, Sergiy
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Asundi, Anand
    Nanyang Technol Univ, Singapore.
    Yu, Yingjie
    Shanghai Univ, Peoples R China.
    Measurement of High Numerical Aperture Cylindrical Surface with Iterative Stitching Algorithm2018In: Applied Sciences, E-ISSN 2076-3417, Vol. 8, no 11, article id 2092Article in journal (Refereed)
    Abstract [en]

    There are some limitations in null test measurements in stitching interferometry. In order to meet the null test conditions, the moving distance between the sub-apertures often deviates from the theoretical preset distance, which leads to a position deviation of sub-apertures when measured. To overcome this problem, an algorithm for data processing is proposed in this paper. An optimal estimation of the deviation between sub-apertures is used to update their positions, and then a new overlapped region is obtained and again optimized. This process is repeated until the algorithm converges to an acceptable tolerance, and finally exact stitching is realized. A cylindrical lens was taken as an object for experimental examination of the proposed method. The obtained results demonstrate the validity, reliability, and feasibility of our iterative stitching algorithm.

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  • 49.
    Cheng, Xiaogang
    et al.
    Nanjing Univ Posts & Telecommun, Coll Telecommun & Informat Engn, Nanjing 210003, Jiangsu, Peoples R China.;Swiss Fed Inst Technol, Comp Vis Lab, CH-8092 Zurich, Switzerland..
    Yang, Bin
    Xian Univ Architecture & Technol, Sch Bldg Serv Sci & Engn, Xian 710055, Shaanxi, Peoples R China.;Umea Univ, Dept Appl Phys & Elect, S-90187 Umea, Sweden..
    Tan, Kaige
    KTH.
    Isaksson, Erik
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID.
    Li, Liren
    Nanjing Tech Univ, Sch Comp Sci & Technol, Nanjing 211816, Jiangsu, Peoples R China..
    Hedman, Anders
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID.
    Olofsson, Thomas
    Umea Univ, Dept Appl Phys & Elect, S-90187 Umea, Sweden..
    Li, Haibo
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID. Nanjing Univ Posts & Telecommun, Coll Telecommun & Informat Engn, Nanjing 210003, Jiangsu, Peoples R China.
    A Contactless Measuring Method of Skin Temperature based on the Skin Sensitivity Index and Deep Learning2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 7, article id 1375Article in journal (Refereed)
    Abstract [en]

    Featured Application The NISDL method proposed in this paper can be used for real time contactless measuring of human skin temperature, which reflects human body thermal comfort status and can be used for control HVAC devices. Abstract In human-centered intelligent building, real-time measurements of human thermal comfort play critical roles and supply feedback control signals for building heating, ventilation, and air conditioning (HVAC) systems. Due to the challenges of intra- and inter-individual differences and skin subtleness variations, there has not been any satisfactory solution for thermal comfort measurements until now. In this paper, a contactless measuring method based on a skin sensitivity index and deep learning (NISDL) was proposed to measure real-time skin temperature. A new evaluating index, named the skin sensitivity index (SSI), was defined to overcome individual differences and skin subtleness variations. To illustrate the effectiveness of SSI proposed, a two multi-layers deep learning framework (NISDL method I and II) was designed and the DenseNet201 was used for extracting features from skin images. The partly personal saturation temperature (NIPST) algorithm was use for algorithm comparisons. Another deep learning algorithm without SSI (DL) was also generated for algorithm comparisons. Finally, a total of 1.44 million image data was used for algorithm validation. The results show that 55.62% and 52.25% error values (NISDL method I, II) are scattered at (0 degrees C, 0.25 degrees C), and the same error intervals distribution of NIPST is 35.39%.

  • 50.
    Cherdantseva, Yulia
    et al.
    Cardiff Univ, Wales.
    Burnap, Pete
    Cardiff Univ, Wales.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Jones, Kevin
    Airbus Grp, Wales.
    A Configurable Dependency Model of a SCADA System for Goal-Oriented Risk Assessment2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 10, article id 4880Article in journal (Refereed)
    Abstract [en]

    A key purpose of a Supervisory Control and Data Acquisition (SCADA) system is to enable either an on-site or remote supervisory control and monitoring of physical processes of various natures. In order for a SCADA system to operate safely and securely, a wide range of experts with diverse backgrounds must work in close rapport. It is critical to have an overall view of an entire system at a high level of abstraction which is accessible to all experts involved, and which assists with gauging and assessing risks to the system. Furthermore, a SCADA system is composed of a large number of interconnected technical and non-technical sub-elements, and it is crucial to capture the dependencies between these sub-elements for a comprehensive and rigorous risk assessment. In this paper, we present a generic configurable dependency model of a SCADA system which captures complex dependencies within a system and facilitates goal-oriented risk assessment. The model was developed by collecting and analysing the understanding of the dependencies within a SCADA system from 36 domain experts. We describe a methodology followed for developing the dependency model, present an illustrative example where the generic dependency model is configured for a SCADA system controlling water distribution, and outline an exemplary risk assessment process based on it.

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