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  • 101.
    Ainouz, Filip
    et al.
    Linköpings universitet, Institutionen för systemteknik.
    Vedholm, Jonas
    Linköpings universitet, Institutionen för systemteknik.
    Mean Value Model of the Gas Temperature at the Exhaust Valve2009Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Over the years many investigations of the gas temperature at the exhaust valve have been made. Nevertheless the modeling of the gas temperature still remains an unsolved problem. This master thesis approaches the problem by attempting to model the exhaust gas temperature by using the standard sensors equipped in SI engines, together with an in-cylinder pressure sensor which is needed in order to develop certain models. The concept in the master thesis is based upon a parameterization of the ideal Otto cycle with tuning parameters which all have physical meanings. Input variables required for the parameterization model is obtained from a fix point iteration method. This method was developed in order to improve the estimates of residual gas fraction, residual gas temperature and variables dependent of those, such as temperature at intake valve closing. The mean value model of the temperature, at the exhaust valve, is based upon the assumption of the ideal gas law, and that the burned gases undergoe a polytropic expansion into the exhaust manifold. Input variables to the entire model are intake manifold pressure, exhaust manifold pressure, intake manifold temperature, engine speed, air mass flow, cylinder pressure, air-to-fuel equivalence ratio, volume, and ignition timing. A useful aspect with modeling the exhaust gas temperature is the possibility to implement it in turbo modeling. By modeling the exhaust gas temperature the control of the turbo can be enhanced, due to the fact that energy is temperature dependent. Another useful aspect with the project is that the model can be utilized in diagnostics, to avoid hardware redundency in the creation of the desired residuals.

  • 102.
    Aitomäki, Yvonne
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Online fibre property measurements: foundations for a method based on ultrasound attenuation2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis presents the foundations of a method for estimating fibre properties of pulp suitable for online application in the pulp and paper industry. In the pulp and paper industry, increased efficiency and greater paper quality control are two of the industry's main objectives. It is proposed that online fibre property measurements are a means of achieving progress in both of these objectives. Optical based systems that provide valuable geometric data on the fibres and other pulp characteristics are commercially available. However, measurements of the elastic properties of the fibres are not currently implemented using these systems. To fill this gap an ultrasound based system for measuring the elastic properties of the wood fibres in pulp is proposed. Ultrasound propagation depends on the elastic properties of a solid. Hence attenuation measurements from suspensions of fibres depend on their elastic properties. The method is based on solving the inverse problem where the output is known and the objective is to establish the inputs. In this case, attenuation is measured and a model of attenuation based on ultrasound scattering is developed. A search algorithm is used for finding elastic properties that minimize the error between the model and measured attenuation. The results of the search are estimates of the elastic properties of the fibres in suspension. The results show resonance peaks in the attenuation, in the frequency region tested, for fibres with radii of the order of 10 microns. These peaks are found in both the measured and modelled attenuation spectra. Further investigation of these resonances suggests that they are due to modes of vibration in the fibre where the fibre modelled as an infinitely long cylinder. These resonances are shown to aid in the identification of the elastic properties. The attenuation is found to depend heavily on the geometry of the fibres. Hence fibre geometry, which can be obtained from online optical fibre measurement system, provides the key to extracting the elastic properties from the attenuation signal. Studies are also carried out on the effect of viscosity on attenuation as well as the differences in attenuation between hollow and solid synthetic fibres in suspensions. The measurement method is also applied to hardwood and softwood Kraft pulps. The results of these studies show that using the model derived in the thesis and attenuation measurements, estimates of the elastic properties can be obtained. The elastic property estimates for synthetic fibres agree well with values from other methods. The elastic property estimates for pulps require further validation due to the difficulty in comparing between different testing methods and different types of pulp. The conclusions, based on the work so far and under three realisable conditions, are that the shear modulus and the transverse Young's modulus of pulp fibres can be measured. Once these conditions are met a system based on this method can be implemented. By doing this the industry would benefit from the increase in paper quality control and energy saving such system could provide.

  • 103.
    Aitomäki, Yvonne
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Towards a measurement of paper pulp quality: ultrasonic spectroscopy of fibre suspensions2006Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    For the paper and pulp industry in Sweden and Finland to remain competitive against countries with lower overheads, they have to constantly strive to improve the quality and the efficiency of the manufacturing processes. One of the ways of doing this is to introduce sensors that will provide valuable online feedback on the characteristics of the pulp so that adjustments can be made to optimise the manufacturing process. The measurement method proposed in this thesis is based on ultrasound, since it is rapid, inexpensive, non-destructive and non-intrusive. Thus could be done online. Since ultrasound propagation and attenuation depends on the material properties through which is propagates, it has the potential to provide measurements of material properties such as pulp fibre density and elasticity. The aim of this thesis is to investigate the possibility of using ultrasound to measure pulp fibre material properties. The idea is to solve the inverse problem of estimating these properties from attenuation measurements and to establish the degree of accuracy to which this can be done. Firstly a model is developed and is tested with synthetic fibres to establish is validity. It is then used to solve the inverse problem of estimating material properties from attenuation measurements, again with synthetic fibres, to test the accuracy to which these properties can be estimated. Resonance peaks in the frequency response of the attenuation were found. On closer investigation it was established that the location of these peaks in the frequency domain is sensitive to the diameter of the fibres and their material properties. If the diameter is known, these peaks improve the accuracy of the estimation process. The results of the estimation process for synthetic fibre suspensions show values for the shear modulus are within known ranges but the estimation of Poisson's ratio and Young's modulus is poor. Improving the model or the estimation procedure may lead to better results. For the method as it is to have application in the paper and pulp industry there are certain conditions that need to be fulfilled. These are that we find peaks in the frequency response of the attenuation in pulp, know the diameter distribution of the fibres and the hollow nature of the fibres does not significantly alter the results. We can then, potentially, be able to establish the shear modulus of the pulp fibres. If the shear modulus is a factor in paper quality, we may be close to an online measurement of paper pulp quality using ultrasonic spectroscopy. Improving the model may allow us to estimate further properties and take into account the fibres being hollow. The thesis consists of two parts. The first part includes an overview of the pulp and paper industry and current testing methods, background theory on which the model is based and an overview of the model that is used in predicting ultrasound attenuation. There then follows a summary of the work done, some addition points are raised in the discussion before drawing conclusions. Finally we discuss what needs to be done to take this further. The second part contains a collection of four papers describing the research.

  • 104.
    Aitomäki, Yvonne
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Berglund, Linn
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Noël, Maxime
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Linder, Tomas
    Löfqvist, Torbjörn
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Light scattering in cellulose nanofibre suspensions: Model and experiments2016Ingår i: Computers in Chemistry Proceeding from ACS National Meeting San Diego: Proceeding from ACS National Meeting San Diego, American Chemical Society (ACS), 2016, s. 122-, artikel-id CELL 235Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Here light scattering theory is used to assess the size distribution in a suspension of cellulose as it is fibrillated from micro-scaled to nano-scaled fibres. A model based on Monte carlo simulations of the scattering of photons by different sizes of cellulose fibres was used to predict the UV-IF spectrum of the suspensions. Bleached cellulose hardwood pulp was tested and compared to the visually transparent tempo-oxidised hardwood cellulose nanofibres (CNF) suspension. The theoretical results show that different diameter size classes exhibit very different scattering patterns. These classes could be identified in the experimental results and used to establish the size class dominating the suspension. A comparison to AFM/microscope size distribution was made and the results indicated that using the UV-IF light scattering spectrum maybe more reliable that size distribution measurement using AFM and microscopy on dried CNF samples. The UV-IF spectrum measurement combined with the theoretical prediction can be used even at this initial stage of development of this model to assess the degree of fibrillation when processing CNF.

  • 105. Aitomäki, Yvonne
    et al.
    Löfqvist, Torbjörn
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Estimating suspended fibre material properties by modelling ultrasound attenuation2006Ingår i: Mathematical Modeling of Wave Phenomena: conference on mathematical modeling of wave phenomea, Växjö, Sweden, 14 - 19 August 2005 / [ed] Börje Nilsson; Louis Fishman, Melville, NY: American Institute of Physics (AIP), 2006, s. 250-259Konferensbidrag (Refereegranskat)
    Abstract [en]

    An analytical model for use in the inverse problem of estimating material properties of suspended fibres from ultrasonic attenuation has been developed. The ultrasound attenuation is derived theoretically from the energy losses arising when a plane wave is scattered and absorbed off an infinitely long, isotropic, viscoelastic cylinder. By neglecting thermal considerations and assuming low viscosity in the suspending fluid, we can make additional assumptions that provide us with a tractable set of equations that can be solved analytically. The model can then be to used in inverse methods of estimating material properties. We verify the model with experimentally obtained values of attenuation for saturated Nylon fibres. The experimental results from Nylon fibres show local peaks in the attenuation which are thought to be due to the resonant absorption at the eigenfrequencies of the fibres. The results of the experiments show that the model is sufficiently sensitive to detect differences in different types of Nylon. Applications for suspended fibre characterization can be found in the paper manufacturing industry.

  • 106. Aitomäki, Yvonne
    et al.
    Löfqvist, Torbjörn
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Material property estimates from ultrasound attenuation in fibre suspensions2009Ingår i: Ultrasonics, ISSN 0041-624X, E-ISSN 1874-9968, Vol. 49, nr 4-5, s. 432-437Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An investigation of a new method for measuring fibre material properties from ultrasonic attenuation in a dilute suspension of synthetic fibres of uniform geometry is presented. The method is based on inversely solving an ultrasound scattering and absorption model of suspended fibres in water for the material properties of the fibres. Experimental results were obtained from three suspensions of nylon 66 fibres each with different fibre diameters. A forward solution to the model with reference material values is compared to experimental data to verify the model's behaviour. Estimates of the shear and Young's modulus, the compressional wave velocity, Poisson's ratio and loss tangent from nylon 66 fibres are compared to data available from other sources. Experimental data confirms that the model successfully predicts that the resonance features in the frequency response of the attenuation are a function of diameter. Consistent estimated values for the compressional wave velocity and the Poisson's ratio were found to be difficult to obtain but in combination gave values of shear modulus within previously reported values and with low sensitivity to noise. Young's modulus was underestimated by 54% but was consistent and had low sensitivity to noise. The underestimation is believed to be caused by the assumption of isotropic material used in the model. Additional tests on isotropic fibre would confirm this. Further analysis of the model sensitivity and the reasons for the resonance features are required.

  • 107.
    Aitomäki, Yvonne
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Löfqvist, Torbjörn
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Sounding Out Paper Pulp: Ultrasound Spectroscopy of Dilute Viscoelastic Fibre Suspensions Acoustics and Ultrasonics2006Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    A model of attenuation of ultrasound in fibre suspensions is compared to a model of backscattering pressure from submersed cylinders subjected to a sound wave. This analysis is carried out in the region where the wavelength is of the same order as that of the diameter of the fibre. In addition we assume the cylinder scatterer to have no intrinsic attenuation and the longitudinal axis of the scatterer is assumed to be perpendicular to the direction of propagation of the incident wave. Peaks in the frequency response of both the backscattering pressure, expressed in the form of a form function, and the attenuation are shown to correspond. Similarities between the models are discussed. Since the peaks in the form function are due to resonance of the cylinder, we infer that the peaks in the attenuation are also due to resonance. The exact nature of the waves causing the resonance are still unclear however the first resonance peaks are related to the shear wave and hence the shear modulus of the material. The aim is to use the attenuation model for solving the inverse problem of calculating paper pulp material properties from attenuation measurements. The implications of these findings for paper pulp property estimation is that the supporting fluid could, if possible, be matched to density of that of pulp fibres and that the estimation of material properties should be improved by selecting a frequency range that in the region of the first resonance peaks.

  • 108.
    Aitomäki, Yvonne
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Löfqvist, Torbjörn
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Delsing, Jerker
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Estimating material properties of solid and hollow fibers in suspension using ultrasonic attenuation2013Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 60, nr 7, s. 1424-1434Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Estimates of the material properties of hollow fibers suspended in a fluid using ultrasound measurements and a simple, computationally efficient analytical model are made. The industrial application is to evaluate the properties of wood fibers in paper pulp. The necessity of using a layered cylindrical model (LCM) as opposed to a solid cylindrical model (SCM) for modeling ultrasound attenuation in a suspension of hollow fibers is evaluated. The two models are described and used to solve the inverse problem of estimating material properties from attenuation in suspensions of solid and hollow polyester fibers. The results show that the measured attenuation of hollow fibers differs from that of solid fibers. Elastic properties estimates using LCM with hollow-fiber suspension measurements are similar to those using SCM with solid-fiber suspension measurements and compare well to block polyester values for elastic moduli. However, using the SCM with the hollow-fiber suspension did not produce realistic estimations. In conclusion, the LCM gives reasonable estimations of hollow fiber properties and the SCM is not sufficiently complex to model hollow fibers. The results also indicate that the use of a distributed radius in the model is important in estimating material properties from fiber suspensions.

  • 109.
    Aizad, Noor
    Linköpings universitet, Institutionen för systemteknik.
    Design and implementation of comparator for sigma delta modulator2006Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    Comparator is the main building block in an ADC architecture. Main purpose of the comparator is to compare a signal with a reference signal and produce an output depending on whether the input signal is greater or smaller than reference. Many architectures for comparators exist for various purposes. In this thesis, Latched comparator architecture is used for sigma delta modulator. This particular design has two main characteristics that are very important for sigma delta application. First characteristic is the cancellation of memory effect which increases the speed and reliability of the system and the second is, with this architecture, high sensitivity can be achieved.

    The design and implementation of lathed comparator for sigma delta modulator is presented in this thesis work. Various non-linearities and performance parameters are discussed in detail. Practical implementation and circuit design issues are highlighted to achieve maximum sensitivity along with reasonable speed and accuracy.

  • 110.
    Akay, Altug
    et al.
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap, Systemsäkerhet och organisation.
    Dragomir, A
    Erlandsson, Björn-Erik
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap, Systemsäkerhet och organisation.
    A Novel Data-Mining Approach Leveraging Social Media to Monitor Consumer Opinion of Sitagliptin2015Ingår i: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 19, nr 1, s. 389-396Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel data mining method was developed to gauge the experience of the drug Sitagliptin (trade name Januvia) by patients with diabetes mellitus type 2. To this goal, we devised a two-step analysis framework. Initial exploratory analysis using self-organizing maps was performed to determine structures based on user opinions among the forum posts. The results were a compilation of user's clusters and their correlated (positive or negative) opinion of the drug. Subsequent modeling using network analysis methods was used to determine influential users among the forum members. These findings can open new avenues of research into rapid data collection, feedback, and analysis that can enable improved outcomes and solutions for public health and important feedback for the manufacturer.

  • 111.
    Akay, Altug
    et al.
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap, Systemsäkerhet och organisation.
    Dragomir, A.
    Erlandsson, Björn-Erik
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap, Systemsäkerhet och organisation.
    A novel data-mining platform leveraging social media to monitor outcomes of Januvia2013Ingår i: Engineering in Medicine and Biology Society (EMBC), 2013 35th Annual International Conference of the IEEE, IEEE conference proceedings, 2013, s. 7484-7487Konferensbidrag (Refereegranskat)
    Abstract [en]

    A novel data-mining method was developed to gauge the experiences of the diabetes mellitus drug Januvia. Self-organizing maps were used to analyze forum posts numerically to infer user opinion of drug Januvia. Graph theory was used to discover influential users. The result is a word list compilation correlating positive and negative word cluster groups and a web of influential users on Januvia. The implications could open new research avenues into rapid data collection, feedback, and analysis that would enable improved solutions for public health.

  • 112.
    Akhtar, Asim
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för datavetenskap, fysik och matematik, DFM.
    Alahi, Hassan Mateen
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för datavetenskap, fysik och matematik, DFM.
    Sehnan, Moeed
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för datavetenskap, fysik och matematik, DFM.
    Simulation of Phased Arrays with Rectangular Microstrip Patches on Photonic Crystal Substrates2012Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis describes the investigation of photonic crystals as a substrate in microstrip phased array antennas. Alumina with a relative dielectric constant of 9.6 is used as substrate to obtain miniaturization of the components in the high-frequency range. The proposed design consists of four rectangular patches in a linear array conguration operating at 12 GHz. The antenna elements are excited by a microstrip feed line using the inset feeding technique for perfect impedance matching. A beam steering of 20o is achieved using a switched line phase shifter. Antenna parameters, including impedance matching, bandwidth, gain, directivity and the S parameters of the proposed array antenna are obtained. The simulation results are obtained with the Advanced Design System (ADS) simulator.

  • 113.
    Akkasli, Cem
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Matematiska och systemtekniska institutionen.
    Methods for Path loss Prediction2009Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Large scale path loss modeling plays a fundamental role in designing both fixed and mobile radio systems. Predicting the radio coverage area of a system is not done in a standard manner. Wireless systems are expensive systems. Therefore, before setting up a system one has to choose a proper method depending on the channel environment, frequency band and the desired radio coverage range. Path loss prediction plays a crucial role in link budget analysis and in the cell coverage prediction of mobile radio systems. Especially in urban areas, increasing numbers of subscribers brings forth the need for more base stations and channels. To obtain high efficiency from the frequency reuse concept in modern cellular systems one has to eliminate the interference at the cell boundaries. Determining the cell size properly is done by using an accurate path loss prediction method. Starting from the radio propagation phenomena and basic path loss models this thesis aims at describing various accurate path loss prediction methods used both in rural and urban environments. The Walfisch-Bertoni and Hata models, which are both used for UHF propagation in urban areas, were chosen for a detailed comparison. The comparison shows that the Walfisch-Bertoni model, which involves more parameters, agrees with the Hata model for the overall path loss.

  • 114.
    Akos, Dennis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Ene, A.
    Stanford University.
    Thor, Jonas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    A prototyping platform for multi-frequency GNSS receivers2003Ingår i: ION GPS/GNSS Proceedings, Institute of Navigation, The , 2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    The future satellite positioning/navigation systems (i.e. GPS and Galileo) will provide civil signals on multiple frequencies, similar to those currently available for military purposes only. This paper presents a direct RF sampling front end design well suited for multiple frequency satellite navigation receiver design. No frequency downconversion is necessary; rather the particular frequency bands of interest are intentionally aliased using a wide band analog-to-digital converter (ADC). The resulting samples are passed to the memory space of a host PC for storage, and are saved to disk for eventual processing of the multiple frequency transmissions. The present paper describes the design of the front-end, validates its concept with collected data, and discusses the variations on the design of a generic multiple frequency GPS front end. Methods for processing the data obtained by the front end design are also presented.

  • 115.
    Akos, Dennis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    From, Markus
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Karlsson, Mattias
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Larsson, Kjell
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Receiver measured time in the VDL mode 4 system2000Ingår i: IEEE 2000 Position Location and Navigation Symposium: San Diego, California, March 13 - 16, 2000, Piscataway, NJ: IEEE Communications Society, 2000, s. 309-316Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper details an investigation into the receiver measured time (RMT) concept of VDL Mode 4, basically the ability to derive estimates of time from the transmission of the VDL Mode 4 signals themselves. The RMT concept is based on determining the accurate time of transmission by measuring the time of arrival (TOA) of a received signal. The reverse aspect, or that of user position, can also be computed in the same manner and all computed simulations hold for errors in position. If synchronized time is available, or can be derived, then the user position can be computed based on signals from known transmitter locations. A complete, end-to-end RMT simulation model for the Gaussian filtered frequency shift keying (GFSK) and differential 8-phase shift keying (D8PSK) modulation techniques has been developed in which various transmitters, channels and receiver models as well as an RMT measurement system have been included. The timing results, which are included, are described in terms of two-sigma errors as a function of signal-to-noise ratios (SNRs). The performance varies for the different receiver structures over the typical operation region and for a 1-bit differential GFSK detector the two-sigma error is as low as 0.40 microseconds, corresponding to a ranging error of approximately 120 meters. When incorporating co-channel interference (CCI), multipath and Doppler frequency shifts the RMT performance has been shown to decrease in terms of higher two-sigma errors

  • 116.
    Akos, Dennis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Stockmaster, Michael
    Rockwell Collins, Cedar Wells.
    Tsui, James B.Y.
    Wright-Patterson Air Force Base, Dayton.
    Caschera, Joe
    Wright-Patterson Air Force Base, Dayton.
    Direct bandpass sampling of multiple distinct RF signals1999Ingår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 47, nr 7, s. 983-988Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A goal in the software radio design philosophy is to place the analog-to-digital converter as near the antenna as possible. This objective has been demonstrated for the case of a single input signal. Bandpass sampling has been applied to downconvert, or intentionally alias, the information bandwidth of a radio frequency (RF) signal to a desired intermediate frequency. The design of the software radio becomes more interesting when two or more distinct signals are received. The traditional approach for multiple signals would be to bandpass sample a continuous span of spectrum containing all the desired signals. The disadvantage with this approach is that the sampling rate and associated discrete processing rate are based on the span of spectrum as opposed to the information bandwidths of the signals of interest. Proposed here is a technique to determine the absolute minimum sampling frequency for direct digitization of multiple, nonadjacent, frequency bands. The entire process is based on the calculation of a single parameter-the sampling frequency. The result is a simple, yet elegant, front-end design for the reception and bandpass sampling of multiple RF signals. Experimental results using RF transmissions from the US Global Positioning System-Standard Position Service (GPS-SPS) and the Russian Global Navigation Satellite System (GLONASS) are used to illustrate and verify the theory

  • 117.
    Al Kadi Jazairli, Mohamad
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Growth of Zinc Oxide Nanoparticles on Top of Polymers and Organic Small Molecules as a Transparent Cathode in Tandem Photovoltaic Device2008Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    Organic solar cells have caught considerable attention in the past few years due to their potential for providing environmentally safe, flexible, lightweight, inexpensive, and roll-to-roll feasible production solar cells. However, the efficiency achieved in current organic solar cells is quite low, yet quick and successive improvements render it as a promising alternative. A hopeful approach to improve the efficiency is by exploiting the tandem concept which consists of stacking two or more organic solar cells in series.

    One important constituent in tandem solar cells is the middle electrode layer which is transparent and functions as a cathode for the first cell and an anode for the second cell. Most studies done so far have employed noble metals such as gold or silver as the middle electrode layer; however, they suffered from several shortcomings especially with respect to reproducibility.

    This thesis focuses on studying a new trend which employs an oxide material based on nano-particles as a transparent cathode (such as Zinc-oxide-nano-particles) along with a transparent anode so as to replace the middle electrode.

    Thus, this work presents a study on solution processable zinc oxide (ZnO) nanostructures, their proper handling techniques, and their potential as a middle electrode material in Tandem solar cells in many different configurations involving both polymer and small molecule materials. Moreover, the ZnO-np potential as a candidate for acceptor material is also investigated.

  • 118.
    Al Khatib, Iyad
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT. iITC, Sweden .
    Ismail, M.
    WNoC: A microelectronic system architecture suitable for biomedical wireless sensor networks2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a low-cost microelectronic system architecture suitable for single chip CMOS integration. The system architecture consists of a large set of on-chip processing-cores, sensors, and four multi-standard wireless border cores that are interconnected to form an ultra-fast microelectronic network of distributed-computing systems. Our main application areas are: biomedical emergency monitoring systems and healthcare. The hardware platform is based on Network-on-Chip (NoC) design and RF circuitry for wireless connectivity. We focus on the design of this Wireless Network-on-Chip (WNoC). WNoC faces several challenges. A main issue of concern from the application point of view is to have the design support the convergence to a decision within acceptable periods of time, because time is critical in many medical healthcare applications. We define a mechanism to enable many WNoCs to interact together over the wireless media. A key result is a design and protocol for internal and external WNoC communications between the main and backup wireless cores. We run simulations on a biomedical monitoring system for emergency situations, and our results show that the time to converge to a medical warning is in the range of milliseconds, which is acceptable for the related medical scenarios.

  • 119.
    Al Tanany, Ahmed
    Högskolan i Gävle, Institutionen för teknik och byggd miljö.
    A Study of Switched Mode Power Amplifiers using LDMOS2007Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    This work focuses on different kinds of Switch Mode Power Amplifiers (SMPAs) using LDMOS technologies. It involves a literature study of different SMPA concepts. Choosing the suitable class that achieves the high efficiency was the base stone of this

    work. A push-pull class J power amplifier (PA) was designed with an integrated LC resonator inside the package using the bondwires and die capacitances. Analysis and motivation of the chosen class is included. Designing the suitable Input/Output printed circuit board (PCB) external circuits (i.e.; BALUN circuit, Matching network and DC

    bias network) was part of the work. This work is done by ADS simulation and showed a simulated result of about 70% drain efficiency for 34 W output power and 16 dB gain at 2.14 GHz. Study of the losses in each part of the design elements is also included.

    Another design at lower frequency (i.e.; at 0.94 GHz) was also simulated and compared to the previous design. The drain efficiency was 83% for 32 W output power and 15.4 dB Gain.

  • 120.
    Ala-Laurinaho, J.
    et al.
    Aalto University, Finland.
    Chicherin, Dmitry
    Aalto University, Finland.
    Du, Zhou
    Aalto University, Finland.
    Simovski, C.
    Aalto University, Finland.
    Zvolensky, T.
    Aalto University, Finland.
    Räisänen, Antti V.
    Aalto University, Finland.
    Sterner, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Baghchehsaraei, Zargham
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Shah, Umer
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Dudorov, Sergey
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Boriskin, A. V.
    IETR, France.
    Le Coq, L.
    IETR, France.
    Fourn, Erwan
    IETR, France.
    Muhammad, S. A.
    IETR, France.
    Sauleau, Ronan
    IETR, France.
    Vorobyov, Alexander
    IETR, France.
    Bodereau, F.
    TRW Autocruise, France.
    El Haj Shhade, G.
    TRW Autocruise, France.
    Labia, T.
    TRW Autocruise, France.
    Mallejac, P.
    TRW Autocruise, France.
    Åberg, Jan
    MicroComp Nordic AB, Sweden.
    Gustafsson, M.
    MicroComp Nordic AB, Sweden.
    Schier, T.
    MicroComp Nordic AB, Sweden.
    TUMESA - MEMS tuneable metamaterials for smart wireless applications2012Ingår i: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012, IEEE , 2012, s. 95-98Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes the main results of the EU FP7 project TUMESA - MEMS tuneable metamaterials for smart wireless applications. In this project, we studied several reconfigurable antenna approaches that combine the new technology of MEMS with the new concept of artificial electromagnetic materials and surfaces (metamaterials and metasurfaces) for realisation of millimetre wave phase shifters and beam-steering devices. MEMS technology allows to miniaturise electronic components, reduce their cost in batch production, and effectively compete with semiconductor and ferroelectric based technologies in terms of losses at millimetre wavelengths. Novel tuneable materials and components proposed in this project perform as smart beam steering devices. Fabricated with MEMS technology in batch and on a single chip, proposed tuneable devices allow substituting of larger and more complex sub-system of, e.g., a radar sensor. This substitution provides a dramatic cost reduction on a system level.

  • 121.
    Alam, Syed Asad
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Implementation of Time-Multiplexed Sparse Periodic FIR Filters for FRM on FPGAs2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Frequency-response masking (FRM) is a set of techniques for lowering the computational complexity of narrow transition band FIR filters. These FRM use a combination of sparse periodic filters and non-sparse filters. In this work we consider the implementation of these filters in a time-multiplexed manner on FPGAs. It is shown that the proposed architectures produce lower complexity realizations compared to the vendor provided IP blocks, which do not take the sparseness into consideration. The designs are implemented on a Virtex-6 device utilizing the built-in DSP blocks.

  • 122.
    Alameddine, Raged
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Dashtbozorg, Sajad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Utredning av för- och nackdelar med TN-S respektive TN-C system2016Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I denna rapport analyseras för- och nackdelar med eldistributionssystem av typ TN-C (fyrledarsystem) respektive TN-S (femledarsystem) system. Det finns olika uppfattningar om vilket system som är lämpligast att bygga ut i distributionsnätet (lågspänningsnätet) och i fastigheternas huvudledning. Med hjälp av litteraturstudier och kontakt med olika elföretag och elbolag har olika ståndpunkter diskuterats och därefter har en sammanställning av resultatet tagits fram. Enligt analysen är TN-C det lämpligaste alternativet att använda i distributionsnätet och TN-S bör användas i fastighetens huvudledning. Detta för att kunna uppnå en god och stabil elmiljö. Detta examensarbete skall underlätta val av teknik och förhoppningsvis öka kunskapen angående ämnet. 

  • 123.
    Alavizadeh, Zahra
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Data- och elektroteknik.
    PLC Controlled System for Local Humidity Management in Electronic Enclosures2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This master thesis is about investigation a power efficient anti-moisture device thatcan be implemented in electronic enclosures in severe climatic environments.First, some of the existing knowledge and previous works were introduced. Then arelevant theoretical background including three main approaches in humiditymanagement are described, comparison between the enclosure heaters and localheaters, some psychrometics concepts that have been used in the project, heattransfer fundamentals, environmental test basics, some humidity and temperaturesensing techniques, computational fluid dynamics, programmable logic controlfundamentals, comparison PLCs with microcontrollers was provided.A series experiments have been performed in order to find the power efficient andmost effective anti-moisture method. Based on the analysis of the experiment data,the local heater system has been designed. CFD assisted parametric study of thelocal heater has been performed in order to find the best feasible design includingthe size and location. The local heater has been built based on the results ofparametric study. Different materials have been tested in laboratory in order tofind the proper material for final prototype of heater. The implemented localheater has been integrated with programmable logic control device. The controlalgorithm has been developed for activation/deactivation of local heater. The logiccontrolled PCB local heater has been experimentally evaluated.In the end the results achieved from environmental test have been presented andanalyzed. Some conclusions on the results and also future work have been discussed.

  • 124.
    Alayon Glazunov, Andres
    et al.
    KTH, Skolan för elektro- och systemteknik (EES). Lund University, Sweden.
    Gustafsson, Mats
    Molisch, Andreas F.
    On the Physical Limitations of the Interaction of a Spherical Aperture and a Random Field2011Ingår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 59, nr 1, s. 119-128, artikel-id 5618544Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper derives physical limitations on the interactions of antennas exciting TM or TE modes (but not both) and wireless propagation channels. The derivation is based on the spherical vector wave expansion of the electromagnetic field outside a sphere circumscribing the antennas. The result is an extension of the seminal work of Chu on the classical limitations on maximum antenna gain and radiation Q. Rather than maximizing antenna gain in a single direction we obtain physical limitations on the antenna gain pattern, which is directly translated to more condensed parameters, i.e., the instantaneous effective gain G(i) and the mean effective gain G(e) if instantaneous realizations or correlation statistics of the expansion coefficients of the electromagnetic field are known, spectively. The obtained limitations are on the maximum of G(i)/Q and G(e)/Q, which establish a trade-off between link gain and Q.

  • 125.
    Albani, Giorgia
    et al.
    University of Milano Bicocca, Italy; Ist Nazl Fis Nucl, Italy.
    Perelli Cippo, Enrico
    CNR, Italy.
    Croci, Gabriele
    University of Milano Bicocca, Italy; Ist Nazl Fis Nucl, Italy.
    Muraro, Andrea
    CNR, Italy.
    Schooneveld, Erik
    Rutherford Appleton Lab, England.
    Scherillo, Antonella
    Rutherford Appleton Lab, England.
    Hall-Wilton, Richard
    European Spallat Source ERIC, Sweden; Mittuniversitetet, Sweden.
    Kanaki, Kalliopi
    European Spallat Source ERIC, Sweden.
    Höglund, Carina
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. European Spallat Source ERIC, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Claps, Gerardo
    Ist Nazl Fis Nucl, Italy.
    Murtas, Fabrizio
    Ist Nazl Fis Nucl, Italy.
    Rebai, Marica
    University of Milano Bicocca, Italy; Ist Nazl Fis Nucl, Italy.
    Tardocchi, Marco
    CNR, Italy.
    Gorini, Giuseppe
    University of Milano Bicocca, Italy; CNR, Italy; Ist Nazl Fis Nucl, Italy.
    Evolution in boron-based GEM detectors for diffraction measurements: from planar to 3D converters2016Ingår i: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 27, nr 11, artikel-id 115902Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The so-called He-3-crisis has motivated the neutron detector community to undertake an intense Ramp;D programme in order to develop technologies alternative to standard He-3 tubes and suitable for neutron detection systems in future spallation sources such as the European spallation source (ESS). Boron-based GEM (gas electron multiplier) detectors are a promising He-3-free technology for thermal neutron detection in neutron scattering experiments. In this paper the evolution of boron-based GEM detectors from planar to 3D converters with an application in diffraction measurements is presented. The use of 3D converters coupled with GEMs allows for an optimization of the detector performances. Three different detectors were used for diffraction measurements on the INES instrument at the ISIS spallation source. The performances of the GEM-detectors are compared with those of conventional He-3 tubes installed on the INES instrument. The conceptual detector with the 3D converter used in this paper reached a count rate per unit area of about 25% relative to the currently installed He-3 tube. Its timing resolution is similar and the signal-to-background ratio (S/B) is 2 times lower.

  • 126.
    Albano, Michele
    et al.
    CISTER, ISEP/INESC-TEC Polytechnic Institute of Porto.
    Barbosa, Paulo Miguel
    CISTER, ISEP/INESC-TEC Polytechnic Institute of Porto.
    Silva, Jose
    CISTER, ISEP/INESC-TEC Polytechnic Institute of Porto.
    Duarte, Roberto
    CISTER, ISEP/INESC-TEC Polytechnic Institute of Porto.
    Ferreira, Luis Lino
    CISTER, ISEP/INESC-TEC Polytechnic Institute of Porto.
    Delsing, Jerker
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Quality of Service on the Arrowhead Framework2017Ingår i: 2017 IEEE 13th International Workshop on Factory Communication Systems (WFCS), Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, artikel-id 7991959Konferensbidrag (Refereegranskat)
    Abstract [en]

    Quality of Service (QoS) is an important enabler for communication in industrial environments. The Arrowhead Framework was created to support local cloud functionalities for automation applications by means of a Service Oriented Architecture. To this aim, the framework offers a number of services that ease application development, among them the QoSSetup and the Monitor services, the first used to verify and configure QoS in the local cloud, and the second for online monitoring of QoS. This paper describes how the QoSSetup and Monitor services are provided in a Arrowhead-compliant System of Systems, detailing both the principles and algorithms employed, and how the services are implemented. Experimental results are provided, from a demonstrator built over a real-time Ethernet network.

  • 127.
    Albertsson, Dagur Ingi
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Zahedinejad, Mohammad
    Department of Physics, University of Gothenburg.
    Åkerman, Johan
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik. Department of Physics, University of Gothenburg.
    Rodriguez, Saul
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Compact Macrospin-Based Model of Three-Terminal Spin-Hall Nano Oscillators2019Ingår i: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 55, nr 10, artikel-id 4003808Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Emerging spin-torque nano oscillators (STNOs) and spin-Hall nano oscillators (SHNOs) are potential candidates for microwave applications. Recent advances in three-terminal magnetic tunnel junction (MTJ)-based SHNOs opened the possibility to develop more reliable and well-controlled oscillators, thanks to individual spin Hall-driven precession excitation and read-out paths. To develop hybrid systems by integrating three-terminal SHNOs and CMOS circuits, an electrical model able to capture the analog characteristics of three-terminal SHNOs is needed. This model needs to be compatible with current electric design automation (EDA) tools. This work presents a comprehensive macrospin-based model of three-terminal SHNOs able to describe the dc operating point, frequency modulation, phase noise, and output power. Moreover, the effect of voltage-controlled magnetic anisotropy (VCMA) is included. The model shows good agreement with experimental measurements and could be used in developing hybrid three-terminal SHNO/CMOS systems.

  • 128.
    Albertsson, Kim
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Gleyzer, Sergei
    University of Florida.
    Zapata, Omar
    OProject and University of Antioquia.
    Machine Learning in High Energy Physics Community White Paper2018Ingår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 1085, artikel-id 022008Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Machine learning is an important applied research area in particle physics, beginning with applications to high-level physics analysis in the 1990s and 2000s, followed by an explosion of applications in particle and event identification and reconstruction in the 2010s. In this document we discuss promising future research and development areas in machine learning in particle physics with a roadmap for their implementation, software and hardware resource requirements, collaborative initiatives with the data science community, academia and industry, and training the particle physics community in data science. The main objective of the document is to connect and motivate these areas of research and development with the physics drivers of the High-Luminosity Large Hadron Collider and future neutrino experiments and identify the resource needs for their implementation. Additionally we identify areas where collaboration with external communities will be of great benefit.

  • 129.
    Al-Breihi, Mohammed
    KTH, Skolan för teknik och hälsa (STH).
    Utveckling av laboration om trefastransformatorn: En studie om transformatorer2014Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Examensarbetet har utforts pa uppdrag av enheten for Data- och

    Elektroteknik pa skolan for Teknik och Halsa, KTH.

    Denna studie om transformatorer omfattar deras funktioner och

    anvandningsomraden, hur de ar uppbyggda, hur karnan och lindningarna

    som ar transformatorns viktigaste delar ar uppbyggda, vilka materiel som

    anvands vid konstruktion av dessa samt vilka typer det finns av dem

    beskrivs i rapporten. Vidare beskrivs flera olika transformatortypers

    funktioner och anvandningsomraden. Eftersom en viktig del av studien

    varit pa vilka satt transformatorer kan utvecklas for okad miljovanlighet

    och livslangd gar rapporten igenom olika vegetabiliska oljor, vilka

    fordelar de har gentemot mineraloljor och vilka egenskaper de har samt

    pa vilket satt de ar skonsammare mot miljon. HVDC-enheter

    transformerar hoga spanningar fran vaxelspanning till likspanning for

    mindre resistiva forluster och darmed lagre energiforluster vilket i sin tur

    leder till en renare miljo.

    Teorigenomgangen av transformatorn ligger till grund for utformningen

    av en laboration for undervisningsbruk, bl.a. i en kurs om elkraftteknik

    som ges i hogskoleingenjorsprogrammet Elektroteknik pa KTH.

  • 130.
    Aldahan, Leith
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Kudoori, Ivan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Utvärdering av roterande borstlösfrekvensomformare tillspårledningar2019Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Spårledningar används inom tunnelbanan för att visa tågets position samt bestämma tågets hastighet genom att bryta spänningsamplituden i signalen vid olika frekvenser. Frekvensen till spårledningen fås från en roterande frekvensomformare. I dagens anläggning används roterande frekvensomformare med borstar. Dessa avger i relärum mycket värme och ger miljöproblem i form av koldamm från borstarna. Det befintliga systemet är gammal och har funnits i drift över 30 år, därför håller reservdelar på att ta slut samt service till systemet svårtillgängligt.

    Detta examensarbete har undersökt möjligheten att uppgradera till nyare system som bygger på en lösning med roterande borstlös frekvensomformare där reservdelarna och service är tillgängliga i minst 25 år.

    Undersökningen jämför olika roterande borstlösa frekvensomformare från olika leverantörer för att hitta en frekvensomformare där kraven från Trafikförvaltningen uppfylls.

    Studien har haft fokus på problemområdet med borstade frekvensomformaren som producerar skadliga ämnen såsom koldamm och värmen i relärum. Diskussioner med tillverkningsföretag av roterande borstlös frekvensomformaren har skett under denna studies gång där möjliga alternativ för vidare utveckling av systemet i relärum analyseras. I projektet har även diskuterat möjligheten att använda det nya systemet av frekvensomformare med borstlösa motor och generator istället för den nuvarande borstade frekvensomformaren som finns i anläggningen. Resultatet har även visat att den roterande borstlösa frekvensomformaren kan omvandla frekvensen till 75 Hz. Det nya systemet uppfyller kraven från Trafikförvaltningen samt att systemet håller i minst 25 år till. Att systemet håller minst i 25 år till var ett stort krav av Trafikförvaltningen som uppfylldes under denna studie.

  • 131.
    Alderisi, Giuliana
    et al.
    University of Catania, Catania, Italy.
    Girs, Svetlana
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Lo Bello, Lucia
    University of Catania, Catania, Italy.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Probabilistic Scheduling and Adaptive Relaying for WirelessHART Networks2015Ingår i: 20th IEEE International Conference on Emerging Technologies and Factory Automation ETFA'15, 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper deals with a way to probabilistically guarantee reliable packet delivery in WirelessHART based networks suitable for industrial control systems. We propose a new scheduling scheme, called Iterative Probabilistic Scheduling with Adaptive Relaying (IPS-AR), which consists of a static part (IPS) and a dynamic part (AR). IPS takes into account the channel characteristics and exploits relaying to achieve a minimum reliability threshold as requested by the supported industrial application. In the AR part, each relay node decides the packet to be sent based on online assessment of both the number of consecutive errors experienced by previous packets belonging to the same flow, as well as the number of copies of the packet currently available at the other relay nodes. This enables IPS-AR to achieve the desired reliability level while using the available re-sources in terms of time and bandwidth more efficiently.

  • 132.
    Aldrin, Martin
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Matematiska och systemtekniska institutionen.
    Implementering av ett inbyggt system för automatisk styrning av en robotbil.2007Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [sv]

    Denna rapport beskriver ett examensarbete för högskoleingenjörsexamen i elektroteknik vid Växjö Universitet. Syftet är att konstruera ett styrsystem till en robotbil, ett program som hindrar bilen från att krocka med omgivningen. Roboten ska även kunna styras från en dator via ett grafiskt gränssnitt implementerat i Labview. Nödvändig hårdvara för styrning och kommunikation har konstruerats.

    Det har behövts tre olika programmeringsspråk för att nå de krav som har ställts på uppgiften, C, Perl och Labview. Microprocessorn i robotbilen har programmerats i C och gör bilen helt autonom, endast beroende av signaler från avståndssensorer. Avlusningsprogrammet skrevs i Perl och styrningen från datorn har implementerats i Labview. Avlusningsprogrammet togs fram på grund av att det blev svårt att hålla koll på allt som skedde med värden och beräkningar i den automatiska styrningen av robotbilen.

  • 133.
    Alene Asres, Georgies
    et al.
    University of Oulu, Finland.
    Dombovari, Aron
    University of Oulu, Finland.
    Sipola, Teemu
    University of Oulu, Finland.
    Puskas, Robert
    University of Szeged, Hungary.
    Kukovecz, Akos
    University of Szeged, Hungary; MTA SZTE Lendulet Porous Nanocomposites Research Grp, Hungary.
    Konya, Zoltan
    University of Szeged, Hungary; MTA SZTE React Kinet and Surface Chemistry Research Grp, Hungary.
    Popov, Alexey
    University of Oulu, Finland.
    Lin, Jhih-Fong
    University of Oulu, Finland.
    Lorite, Gabriela S.
    University of Oulu, Finland.
    Mohl, Melinda
    University of Oulu, Finland.
    Toth, Geza
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad sensorvetenskap. Linköpings universitet, Tekniska fakulteten. University of Oulu, Finland.
    Kordas, Krisztian
    University of Oulu, Finland.
    A novel WS2 nanowire-nanoflake hybrid material synthesized from WO3 nanowires in sulfur vapor2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, nr 25610Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, WS2 nanowire-nanoflake hybrids are synthesized by the sulfurization of hydrothermally grown WO3 nanowires. The influence of temperature on the formation of products is optimized to grow WS2 nanowires covered with nanoflakes. Current-voltage and resistance-temperature measurements carried out on random networks of the nanostructures show nonlinear characteristics and negative temperature coefficient of resistance indicating that the hybrids are of semiconducting nature. Bottom gated field effect transistor structures based on random networks of the hybrids show only minor modulation of the channel conductance upon applied gate voltage, which indicates poor electrical transport between the nanowires in the random films. On the other hand, the photo response of channel current holds promise for cost-efficient solution process fabrication of photodetector devices working in the visible spectral range.

  • 134.
    Alepuz, Javier Pérez
    et al.
    University of Alicante.
    Emami, Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Pomares, Jorge
    University of Alicante.
    Direct image-based visual servoing of free-floating space manipulators2016Ingår i: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 55, s. 1-9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents an image-based controller to perform the guidance of a free-floating robot manipulator. The manipulator has an eye-in-hand camera system, and is attached to a base satellite. The base is completely free and floating in space with no attitude control, and thus, freely reacting to the movements of the robot manipulator attached to it. The proposed image-based approach uses the system's kinematics and dynamics model, not only to achieve a desired location with respect to an observed object in space, but also to follow a desired trajectory with respect to the object. To do this, the paper presents an optimal control approach to guiding the free-floating satellite-mounted robot, using visual information and considering the optimization of the motor commands with respect to a specified metric along with chaos compensation. The proposed controller is applied to the visual control of a four-degree-of-freedom robot manipulator in different scenarios.

  • 135.
    Alfieri, Luisa
    et al.
    Department of Engineering, University of Naples Parthenope, Centro Direzionale of Naples.
    Bracale, Antonio
    Department of Engineering, University of Naples Parthenope, Centro Direzionale of Naples.
    Carpinelli, Guido
    Department of Electrical Engineering and Information Technology, University of Naples Federico II.
    Larsson, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Accurate assessment of waveform distortions up to 150 kHz due to fluorescent lamps2017Ingår i: 2017 6th International Conference on Clean Electrical Power: Renewable Energy Resources Impact, ICCEP 2017, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 636-644, artikel-id 8004756Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fluorescent lamps are among the most diffuse electrical components that introduce significant waveform distortions in low voltage distribution systems. These distortions involve a wide range of frequencies (i.e., from 0 kHz to 150 kHz), and spectral components characterized by a non-uniform behavior in time and frequency domains. Early IEC standards covered formally only the range from 0 kHz to 9 kHz, defining grouping and group total harmonic distortion both for the low-frequencies (i.e., from 0 kHz to 2 kHz) and for frequencies ranging from 2 kHz to 9 kHz. Recently, the IEC standards have suggested to extend the grouping, previously defined for the range from 2 kHz to 9 kHz, also to the range from 9 kHz to 150 kHz. In this paper, the waveform distortions of a variable number of fluorescent lamps were quantified by applying the main Power Quality indices currently available for such devices. Indices are evaluated using both the IEC method and an hybrid method proposed recently in the relevant literature, i.e., the sliding-window Wavelet-Modified ESPRIT method. Numerical applications on measured data show the waveform distortion levels versus the number of lamps, quantifying also the different performances of the aforesaid spectral analysis methods

  • 136.
    Alfieri, Luisa
    et al.
    Department of Electrical Engineering and Information Technology, University of Naples Federico II, Italy.
    Bracale, Antonio
    Department of Engineering, University of Naples Parthenope, Centro Direzionale of Naples.
    Larsson, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    New Power Quality Indices for the Assessment of Waveform Distortions from 0 to 150 kHz in Power Systems with Renewable Generation and Modern Non-Linear Loads2017Ingår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, nr 10, artikel-id 1633Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The widespread use of power electronics converters, e.g., to interface renewable generation systems with the grid or to supply some high-efficiency loads, has caused increased levels of waveform distortions in the modern distribution system. Voltage and current waveforms include spectral components from 0 kHz to 150 kHz, characterized by a non-uniform time-frequency behavior. This wide interval of frequencies is currently divided into "low-frequency" (from 0 kHz to 2 kHz) and "high-frequency" (from 2 kHz to 150 kHz). While the low-frequencies have been exhaustively investigated in the relevant literature and are covered by adequate standardization, studies for the high-frequencies have been addressed only in the last decade to fill current regulatory gaps. In this paper, new power quality (PQ) indices for the assessment of waveform distortions from 0 kHz to 150 kHz are proposed. Specifically, some currently available indices have been properly modified in order to extend their application also to wide-spectrum waveforms. In the particular case of waveform distortions due to renewable generation, numerical applications prove that the proposed indices are useful tools for the characterization of problems (e.g., overheating, equipment malfunctioning, losses due to skin effects, hysteresis losses or eddy current losses) in cases of both low-frequency and high-frequency distortions

  • 137.
    Alfredsson, Jon
    Linköpings universitet, Institutionen för systemteknik.
    Design of a parallel A/D converter system on PCB: For high-speed sampling and timing error correction2002Självständigt arbete på grundnivå (yrkesexamen)Studentuppsats
    Abstract [en]

    The goals for most of today’s receiver system are sampling at high-speed, with high resolution and with as few errors as possible. This master thesis describes the design of a high-speed sampling system with"state-of-the-art"components available on the market. The system is designed with a parallel Analog-to-digital converter (ADC) architecture, also called time interleaving. It aims to increase the sampling speed of the system. The system described in this report uses four 12-bits ADCs in parallel. Each ADC can sample at 125 MHz and the total sampling speed will then theoretically become 500 Ms/s. The system has been implemented and manufactured on a printed circuit board (PCB). Up to four boards can be connected in parallel to get 2 Gs/s theoretically.

    In an approach to increase the systems performance even further, a timing error estimation algorithm will be used on the sampled data. This algorithm estimates the timing errors that occur when sampling with non-uniform time interval between samples. After the estimations, the sampling clocks can be adjusted to correct the errors.

    This thesis is concerning some ADC theory, system design and PCB implementation. It also describes how to test and measure the system’s performance. No measurement results are presented in this thesis because measurements will be done after this project. The last part of the thesis discusses future improvementsto achieve even higher performance.

  • 138.
    Alfredsson, Jon
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Aunet, Snorre
    Department of Informatics, University of Oslo.
    Oelmann, Bengt
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Basic Speed and Power Properties of Digital Floating-gate Circuits Operating in Subthreshold2005Ingår i: Proceedings of IFIP VLSI-SOC 2005: International Conference on Very Large Scale Integration, Edith Cowan Univ , 2005, s. 229-232Konferensbidrag (Refereegranskat)
    Abstract [en]

    For digital circuits with ultra-low power consumption,floating-gate circuits have been considered to be a techniquepotentially better than standard static CMOS circuits.By having a DC offset on the floating gates, theeffective threshold voltage of the floating-gate transistoris adjusted and the speed and power performance can bealtered. In this paper the basic performance related propertiessuch as power, delay, power-delay product (PDP),and energy-delay product (EDP) for floating-gate circuitsoperating in subthreshold are investigated. Based on circuitsimulations in a 120nm process technology, it isshown that for the best case, the power can be reducedapproximately by one order of magnitude at the expenseof increased delay, while the PDP is more or less constantin comparison to static CMOS. The EDP can be reducedby two orders of magnitude at the expense of reducednoise margins.

  • 139.
    Alfredsson, Sandra
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Model Based Diagnosis of an Air Source Heat Pump2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The purpose of a heat pump is to control the temperature of an enclosed space. This is done by using heat exchange with a heat source, for example water, air, or ground. In the air source heat pump that has been studied during this master thesis, a refrigerant exchanges heat with the outdoor air and with a water distribution system.

    The heat pump is controlled through the circuit containing the refrigerant and it is therefore crucial that this circuit is functional. To ensure this, a diagnosis system has been created, to be able to detect and isolate sensor errors. The diagnosis system is based on mathematical models of the refrigerant circuit with its main components: a compressor, an expansion valve, a plate heat exchanger, an air heat exchanger, and a four-way valve. Data has been collected from temperature- and pressure sensors on an air source heat pump. The data has then been divided into data for model estimation and data for model validation. The models are used to create test quantities, which in turn are used by a diagnosis algorithm to determine whether an error has occurred or not.

    There are nine temperature sensors and two pressure sensors on the studied air source heat pump. Four fault modes have been investigated for each sensor: Stuck, Offset, Short circuit and Open circuit. The designed diagnosis system is able to detect all of the investigated error modes and isolate 40 out of 44 single errors. However, there is room for improvement by constructing more test quantities to detect errors and decouple more fault modes. To further develop the diagnosis system, the existing models can be improved and new models can be created.

  • 140.
    Alfrijat, Christopher
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Eriksson, Rasmus
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Analys och utvärdering av LED-belysning i Stockholms tunnelbana2019Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Trafikförvaltningen, som ansvarar för kollektivtrafiken i Stockholm, har startat ett projekt för att byta ut befintliga armaturer i Stockholms tunnelbana mot LED-armaturer. Denna rapport utför förarbetet inför en kommande upphandling.

    Detta arbete utvärderar olika LED-armaturers tekniska specifikationer som är lämpliga för Stockholms tunnelbana där armaturerna ska bytas ut. För denna miljö saknas det i dagsläget standarder som är anpassade för LED-armaturer. Med hjälp av litteraturstudier och mätningar kunde underlag för en kravspecifikation skapas. Mätningar har gjorts på ett urval av LED-armaturer och deras tekniska specifikation har presenterats. Samtliga armaturer klarade EMC-testerna (elektromagnetisk kompabilitet) där inga störningar uppstod vid frekvenserna för Storstockholms Lokaltrafiks (SL) radiokommunikationssystem.

    Arbetet har även hanterat miljö- samt den ekonomiska aspekten av implementeringen av LED-belysning.

  • 141.
    Algers, Björn
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Stereo Camera Calibration Accuracy in Real-time Car Angles Estimation for Vision Driver Assistance and Autonomous Driving2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Bilsäkerhetsföretaget Veoneer är utvecklare av avancerade kamerasystem inom förarassistans, men kunskapen om den absoluta noggrannheten i deras dynamiska kalibreringsalgoritmer som skattar fordonets orientering är begränsad.

    I denna avhandling utvecklas och testas ett nytt mätsystem för att samla in referensdata av ett fordons orientering när det är i rörelse, mer specifikt dess pitchvinkel och rollvinkel. Fokus har legat på att skatta hur osäkerheten i mätsystemet påverkas av fel som introducerats vid dess konstruktion, samt att utreda dess potential när det kommer till att vara ett gångbart alternativ för att samla in referensdata för evaluering av prestandan hos algoritmerna.

    Systemet bestod av tre laseravståndssensorer monterade på fordonets kaross. En rad mätförsök utfördes med olika störningar introducerade genom att köra längs en vägsträcka i Linköping med vikter lastade i fordonet. Det insamlade referensdatat jämfördes med data från kamerasystemet där bias hos de framräknade vinklarna skattades, samt att de dynamiska egenskaperna kamerasystemets algoritmer utvärderades. Resultaten från mätförsöken visade på att noggrannheten i mätsystemet översteg 0.1 grader för både pitchvinklarna och rollvinklarna, men några slutsatser kring eventuell bias hos algoritmerna kunde ej dras då systematiska fel uppstått i mätresultaten.

  • 142.
    Alhamarna, Ahmed
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi.
    Kjellgren, Simon
    Högskolan i Halmstad, Akademin för informationsteknologi.
    IDENTIFIERING AV ELEKTRONIKSKROT2017Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport a ̈r resultatet av en underso ̈kning gjord p ̊a bega ̈ran av ett ̊ater- vinningsfo ̈retag, vars o ̈nskan var att unders ̈oka mo ̈jligheter f ̈or att effektivisera sorteringsprocessen av elektroniskt skrot i deras ̊atervinningslokal. Metoden som underso ̈ks a ̈r om RFID skulle kunna anv ̈andas f ̈or identifiering av skrotet. Projektmedlemmarna bo ̈rjade sitt arbete med att unders ̈oka om RFID var den b ̈asta identifieringsmetoden, d ̈ar f ̈or och nackdelar med olika automatiska identifikationssystem ja ̈mf ̈ordes. Slutsatsen av arbetet var att RFID skulle kunna vara en h ̊allbar lo ̈sning i framtiden fo ̈rutsatt att elektronikproducen- ter integrerar RFID taggar i sina produkter. Med tanke p ̊a att fler och fler producenter anva ̈nder RFID fo ̈r att lokalisera och identifiera sina produkter under tillverkning och det sjunkande priset p ̊a passiva taggar, ̈ar det mo ̈jligt att RFID-ma ̈rkning av produkter skulle kunna bli en standard i framtiden, b ̊ade f ̈or effektivare logistik och f ̈or en effektivare ̊atervinningsprocess. 

  • 143. Al-Hammouri, A.T.
    et al.
    Nordström, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Chenine, Moustafa
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Honeth, Nicholas
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Leelaruji, Rujiroj
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Virtualization of synchronized phasor measurement units within real-time simulators for smart grid applications2012Ingår i: Power and Energy Society General Meeting, 2012 IEEE, IEEE , 2012, s. 6344949-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Synchronized phasor measurement units (PMUs) provide GPS-time tagged high-sampling rate positive-sequence voltage and current phasors. When placed in high-voltage substations in power networks, PMUs can provide real-time information that is necessary for the development of Smart Transmission Grid software applications for improving power system monitoring, control and protection. The development of these applications, particularly for use within control centers for on-line purposes, is limited by the availability of and access to real-time PMU data and other information. One attractive approach for application development is the use of real-time simulators to which PMUs can be interfaced as hardware-in-the-loop (HIL) devices to harvest PMU data. However, this approach has technical and economical limitations, which can be tackled by the virtualization of PMU devices. This article describes the development of an entirely software-based synchronized phasor measurement unit for use within real-time simulators that will allow the emulation of a large number of real-life PMUs, which in turn can be used for creating new phasor-based applications.

  • 144.
    Ali M., Ahmed
    et al.
    University of Duisburg-Essen.
    Moulik, Bedatri
    Amity University.
    Beganovic, Nejra
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Söffker, Dirk
    University of Duisburg-Essen.
    A State-of-Health-Oriented Power Management Strategy for Multi-Source Electric Vehicles Considering Situation-Based Optimized Solutions in Real-Time2019Ingår i: Proceedings of the Annual Conference of the PHM Society 11 (1), Scottsdale, Arizona, USA: PHM Society , 2019, Vol. 11, s. 1-10, artikel-id 783Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a novel situation-based power and battery health management strategy for fuel cell vehicles. In such hybrid powertrains, the synergy role of batteries is essential to minimize overall power consumption and maintain higher electrical efficiency of the fuel cell. On the other hand, lifetime degradation of the battery is associated with the recurrent charging / discharging cycles. The proposed power management strategy addresses the trade-off between these contradictory objectives. Vehicle states in each situation are defined in terms of driver-related identification parameters (power demand and speed) corporately with powertrain related ones (on-board battery's state of charge). Optimal power handling solution for each situation is searched offline considering different optimization criteria: range extension, lifetime maximization, or power consumption minimization. A weighted fusion of these optimized solutions can be implemented online based on desired driving strategy, leading to situation-based optimized solution. This contribution aims to provide flexible power handling options meeting performance requirements (energy efficiency and driveability) without scarifying battery life. Simulation tests using different driving cycles are conducted for evaluation purpose.

  • 145. Ali, Muhammad
    et al.
    Matevosyan, Julija
    Milanovic, J. V.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Effect of wake consideration on estimated costs of wind energy curtailments2009Ingår i: 8th International Workshop on Large Scale Integration of Wind Power into Power Systems as well as on Transmission Networks of Offshore Wind Farms, 14-15 Oct. 2009 Bremen, 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Measures such as energy curtailment or gridreinforcement are required to integrate the upcoming windgeneration in parts of the power system with existing transmissionbottlenecks. In order to choose between these two measurespotential wind energy curtailments and its costs need to becarefully evaluated. The paper analyzes the effect of wakeconsideration on the overall energy curtailment cost. For thispurpose detailed wake model was used taking into account partialand multiple shading of wind turbines. It is shown that not onlywind speed but also wind direction of the incoming wind affects theamount of energy produced by a wind farm. A comparison ofcurtailment cost with cost for grid reinforcement in areas withlimited transmission capacity was carried out with and withoutconsideration of wake effect. The effect on curtailment cost due toavailability of wind turbines is also investigated both with andwithout wake effect consideration. The results have proven thatwith consideration of wake effect and availability potential windenergy curtailments are reduced and hence curtailment costs arelowered, making curtailment a cheaper option than gridreinforcement. The method illustrated in the paper can be used inpre-feasibility study to compare the costs of wind curtailment withthe costs of grid reinforcement in order to make sound economicdecision. The method can also be applied in wind farm energy yield estimation.

  • 146.
    Ali, Muhammad Taha
    et al.
    National University of Science and Technology Islamabad, Pakistan.
    Anwar, Ali
    Tayyab, Umais
    Iqbal, Yasir
    Tauqeer, Tauseef
    Nasir, Usman
    Design of High Efficiency Wireless Power Transmission System at Low Resonant Frequency2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a novel design of a wireless power transmission system which transfers an appreciable amount of electrical power wirelessly using low resonant frequency, with an excellent efficiency, and has a very low cost implementation. The designs of induction coils at both source and receiver sides are also presented in this paper. The mechanism for power transmission is through electro-magnetic induction. Also an immense knowledge of electronics was applied in order to design the source and receiver between which this transfer took place. In order to realize this method an AC-AC converter, and AC-DC rectifier were used at source and receiver sides respectively along with the resonant circuits. The work was carried out by the experimental setup and results demonstrate that proposed system design can successfully transfer the amount of power that can be used in many practical applications.

  • 147.
    Ali, Muhammad Taha
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Ghandhari, Mehrdad
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Harnefors, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Effect of control parameters on infliction of sub-synchronous control interaction in DFIGs2016Ingår i: 2016 IEEE International Conference on Power and Renewable Energy (ICPRE), IEEE conference proceedings, 2016, s. 72-78, artikel-id 7871175Konferensbidrag (Refereegranskat)
    Abstract [en]

    This research work deals with the analysis of sub-synchronous control interaction (SSCI) in doubly-fed induction generators (DFIGs). The time-invariant model of the DFIG is linearized to perform eigenvalue analysis and to obtain the participation factor of each state variable for unstable modes. The sensitivity of system eigenvalues related to sub-synchronous modes is analyzed with respect to all the proportional and integral parameters of the controllers in the rotor-side-converters and grid-side-converters. The major contribution of this research work is the outcomes based on eigenvalue analysis that clearly point out the control parameters to which sub-synchronous modes are highly sensitive. The effect of series compensation level on DFIG system and on the sensitivity of converter control parameters is also studied.

  • 148.
    Ali Shah, Syed Asmat
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Qazi, Sohaib Ayaz
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Design of an all-digital, reconfigurable sigma-deltamodulator2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis presents a model of reconfigurable sigma-delta modulator. These modulators areintended for high speed digital Digital to Analog Converters. The modulators are intendedto reduce complexity of current steering DACs and also considered as a front end of dataconverters. Quantization noise present in digital signal is pushed to higher frequencies bysigma-delta modulators. Noise in high band frequencies can be removed by a low pass filter.

    A test methodology involving generation of baseband signal, interpolation and digitizationis opted. Topologies tested in MATLAB® include signal feedback and error feedback modelsof first-order and second-order sigma-delta modulators. Error feedback and signal feedbackfirst-order modulators’ performance is quite similar. The SNR of a first-order error feedbackmodel is 52.3 dB and 55.9 dB for 1 and 2 quantization bits, respectively. In second-orderSDM, signal feedback provides best performance with 80 dB SNR.

    The other part of the thesis focuses on the implementation of the sigma-delta modulator(SDM) using faster time to market approach. SoC Encounter, a tool from Cadence, is theeasiest way to do this job. The modulators are implemented in 65-nm technology. The reconfigurablesigma-delta modulator is designed using Verilog-HDL language. Switches areintroduced to control the reconfigurable SDM for different input word lengths. Word-lengthcan vary from 0 to 4 bits. Modulator is designed to work for frequencies of 2 GHz. To netlistthe design, Design Compiler is used which is a tool from Synopsys®.

    The area of the chip reported by design compiler is 563.68 um. When the design is implementedin SoC Encounter, area of the chip is increased, because the core utilization, whiledesigning, is only 60%, which is 556.8 um. Remaining 40% area is used by buffers, inverterand filler cells during clock tree synthesis. The buffers and inverters are added to removethe clock phase delay between different registers. Power consumption of the chip is 319mW.Internal power of the modulators is 219.1 mW. Switching power of output capacitances is99.9 mW, which is 31% of the total power consumed. Main concern of the power loss isconsidered to be power leakage. To reduce the leakage power and achieve high speed designCORE65GPHVT libraries are used. Leakage power of the design is 2.825 uW which is0.00088% of the total power.

  • 149.
    Ali-Eldin, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Rezaie, Ali
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Mehta, Amardeep
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Razroev, Stanislav
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Sjöstedt-de Luna, Sara
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Seleznjev, Oleg
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    How will your workload look like in 6 years?: Analyzing Wikimedia's workload2014Ingår i: Proceedings of the 2014 IEEE International Conference on Cloud Engineering (IC2E 2014) / [ed] Lisa O’Conner, IEEE Computer Society, 2014, s. 349-354Konferensbidrag (Refereegranskat)
    Abstract [en]

    Accurate understanding of workloads is key to efficient cloud resource management as well as to the design of large-scale applications. We analyze and model the workload of Wikipedia, one of the world's largest web sites. With descriptive statistics, time-series analysis, and polynomial splines, we study the trend and seasonality of the workload, its evolution over the years, and also investigate patterns in page popularity. Our results indicate that the workload is highly predictable with a strong seasonality. Our short term prediction algorithm is able to predict the workload with a Mean Absolute Percentage Error of around 2%.

  • 150.
    Alirezaie, Marjan
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Loutfi, Amy
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Reasoning for Improved Sensor Data Interpretation in a Smart Home2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper an ontological representation and reasoning paradigm has been proposed for interpretation of time-series signals. The signals come from sensors observing a smart environment. The signal chosen for the annotation process is a set of unintuitive and complexgas sensor data. The ontology of this paradigm is inspired form the SSNontology (Semantic Sensor Network) and used for representation of both the sensor data and the contextual information. The interpretation process is mainly done by an incremental ASP solver which as input receivesa logic program that is generated from the contents of the ontology. The contextual information together with high level domain knowledge given in the ontology are used to infer explanations (answer sets) for changes in the ambient air detected by the gas sensors.

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