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  • 51.
    Andersson, Karin
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Work environment, Lean and Agriculture2014In: PROCEEDINGS: 11th International Symposium on Human Factors in Organisational Design and Management & 46th Annual Nordic Ergonomics Society Conference: Volume I + II, IEA Press , 2014, p. 661-666Conference paper (Refereed)
    Abstract [en]

    Lean has become the predominant management concept in industry, but its effect on the work environment is debated. Lean has now reached farms and garden nurseries. This paper aims to identify consequences for the physical and psychosocial work environment when Lean was applied in micro-businesses in the agricultural sector. Observations, a questionnaire and interviews were used as methods. It was concluded that the psychosocial work environment became more structured and less stressful. The physical work environment was partly improved by less transportation on the farm. However, consideration of the physical work environment was insufficient.

  • 52.
    Andersson, Katarina
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Optimization of the Implantation Angle for a Talar Resurfacing Implant: A Finite Element Study2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Osteochondral lesions of the talus (OLTs) are the third most common type of osteochondral lesion and can cause pain and instability of the ankle joint. Episurf Medical AB is a medical technology company that develops individualized implants for patients who are suffering from focal cartilage lesions. Episurf have recently started a project that aims to implement their implantation technique in the treatment of OLTs.

    This master thesis was a part of Episurf’s talus project and the main goal of the thesis was to find the optimal implantation angle of the Episurf implant when treating OLTs. The optimal implantation angle was defined as the angle that minimized the maximum equivalent (von Mises) strain acting on the implant shaft during the stance phase of a normal gait cycle. It is desirable to minimize the strain acting on the implant shaft, since a reduction of the strain can improve the longevity of the implant.

    To find the optimal implantation angle a finite element model of an ankle joint treated with the Episurf implant was developed. In the model an implant with a diameter of 12 millimeters was placed in the middle part of the medial side of the talar dome. An optimization algorithm was designed to find the implantation angle, which minimized the maximum equivalent strain acting on the implant shaft. The optimal implantation angle was found to be a sagittal angle of 12.5 degrees and a coronal angle of 0 degrees. Both the magnitude and the direction of the force applied to the ankle joint in the simulated stance phase seemed to influence the maximum equivalent strain acting on the implant shaft.

    A number of simplifications have been done in the simulation of this project, which might affect the accuracy of the results. Therefore it is recommended that further, more detailed, simulations based on this project are performed in order to improve the result accuracy.

  • 53.
    Andersson, Katarina
    et al.
    KTH, School of Technology and Health (STH).
    Löfgren, Carita
    KTH, School of Technology and Health (STH).
    Partial Development of a Water Purification System Using Heat from Solar Energy, with Focus on Bangladesh2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 54.
    Andersson, Klara
    et al.
    KTH, School of Technology and Health (STH).
    Busch Paulsson, Esther
    KTH, School of Technology and Health (STH).
    Utvärdering av användarvänlighet hos hjälpmedel för ät-träning2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Mandometer® is a medical device, which assists patients with overweight and eating disorders to normalize their eating beahavior. Mandometer® has been developed by Mando Group AB and is used on Mandometer- and Mandolean Clinics in Sweden, USA and Australia in their treatment. A new version of Mandometer® has been recently developed, from generation four to generation five. It consists of a light scale and a mobile app, instead of a scale and a computer.  No previous study about the usability of the new version has been done. On behalf of Mando Group AB has such an evaluation been executed using questionnaires and conversations with both patients and healthy individuals. The results have been compiled and analyzed, and based on this a conclusion has been drawn. The usability is sufficient, but there are some deficiencies. This can be fixed by the suggested improvements and the written instruction manual. The result also shows that the development of the product is a clear improvement compared to the previous version.

  • 55.
    Andersson, Lars
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Hansson, Mats
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Systematisk kunskapsbrist i skolan?: Arbetsmiljöarbete utan udd2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Swedish employers are obliged by law to systematically plan, direct and control activities so that the working environment meets the prescribed requirements. However, evidence indicates that this work is not performed satisfactorily in many schools. This case study aims at mapping out and clarifying how measures towards planning, directing and controlling activities are organized in two public compulsory schools.

     

    The overall purpose of the study is to shed light on elements and conditions that hinder a successful implementation of work environment measures. Our main research questions are: Does the way the municipalities have organized the working environment measures reach the requirements in the law and how controls and follow-ups are performed. Data was collected through the municipalities’ steering documents together with a survey in combination with follow-up interviews with key figures.

     

    Results show that the working environment measures in both schools are organized and performed in similar ways and that the problems reported to a large extent are the same. The unanimous picture shows an organization that is not capable of identifying and handling all important risks. Conclusions from the study indicate that there is a lack of knowledge concerning working environments measures on all levels in the organizations.

  • 56.
    Andersson, Lisa
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Det passar inte alla: Arbetstillfredställelse, produktivitet och stress i kontorslandskap2016Independent thesis Advanced level (degree of Master (One Year)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The open-plan offices at Boliden has been renovated. The company wanted an evaluation of what the employees thought about the physical work environment in the new offices. The company also wanted the study to present improvement for deficiencies in the physical environment.

     

    The aim of this study was to identify positive and negative aspects of the physical working environment factors and to identify correlation between the physical work environment factors and job satisfaction, productivity and stress. A second purpose was also to present some improvement for the physical work environment. A part of the questionnaire was to evaluate if there existed any difference between the sexes regarding the physical work environment. To examine these aspects this study used a questionnaire as well a system group seminar to develop possible improvements.

     

    The results from the questionnaire show that the employees were pleased with the ventilation, the furniture’s functionality and the aesthetics of the office. The questionnaire also found dissatisfaction with glare, outlook and temperature but mostly the audial privacy in the office.

     

    Previous studies have shown that there is a correlation between physical work environment factors, job satisfaction and productivity but inconsistent evidence for work environment and stress. This study showed significant relationship between the auditory privacy, job satisfaction and productivity but not between auditory privacy and stress, which corresponds to the previous studies.

     

    The improvements presented at the system group seminar was to introduce guidelines to reduce noise and divide the office into smaller offices. To improve the auditory privacy this study suggests that a combination of redeploying employees in the open-plan office, dividing the office in to smaller office areas and introduces guidelines of how the employees should behave in the open-plan office.

  • 57.
    Andersson, Olle
    KTH, School of Technology and Health (STH).
    Characterization of an On-chip Photonic Waveguide gas Sensor2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Gas sensing in medical applications requiresmall, precise and sensitive sensors. This projecthas developed a laboratory setup for characterisationof a waveguide-based gas sensor for carbon dioxide andmethane working in the mid-IR range of 2 - 10 μm. Thissetup utilizes an IR-camera to image the waveguideswhen a mid-IR laser is coupled into them. Along thelaboratory work, a program for optimisation of waveguidelength has been made and a study of on-marketmedical carbon dioxide sensors has been done. Thelaboratory setup shows potential for good measurementof waveguide losses, but several problems was identifiedwith the measurement methods currently used. Fromthe sensor study, the standard performance for currentsensors is presented as well as areas where gas sensorscould be improved. Size, speed and accuracy were someof the characteristics a waveguide-based sensor couldimprove on and open up for new sensor application in,for example, hand-held medical devices.

  • 58. Andersson, Per
    et al.
    Björkholm, Peter
    Haasl, Sjoerd
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Johannisson, Pontus
    Johnsson, Christer
    Stigwall, Johan
    Södermalm, Svante
    MEMS-based inertial navigation instrumentation for high-dynamic applications2009In: COMS 2009, 2009Conference paper (Refereed)
  • 59.
    Andersson, Simon
    et al.
    KTH, School of Technology and Health (STH).
    Lundberg, Fabian
    KTH, School of Technology and Health (STH).
    Analys av resursbehovet per patient på akutmottagningen vid Karolinska Universitetssjukhuset Solna2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The staff of the emergency department at Karolinska Universitetssjukhuset Solna has in recent years experienced a higher workload, although the number of patients has not increased. Karolinska Universitetssjukhuset do not possess a set method to analyze the resource needs of different patient groups, and the difference between them. The project would thus give Karolinska Universitetssjukhuset a better understanding of different patients' resource needs in the form of a resource consumption model. This model was created through discussions with staff and analysis of data from Karolinska's internal data warehouse, Karda. From this a patient group distribution was created with the aim of grouping patients with similar resource needs. Time studies and surveys were conducted and compiled at the emergency department to generate important information. Analysis of the results obtained suggests that patients have, in recent years, become more ill and therefore more costly for the hospital. A resource consumption model has been created which can analyze and compare the patients' burden of care with one another by three parameters. These are priority and monitoring, period of residence and on-call salary increment. However, this model is not currently able to analyze all parameters simultaneously, only individually. In order to analyze parameters simultaneously the model and calculations would need to be revised. This could be a continuous study for further work in this specific area.  

  • 60.
    Antoni, Per
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hed, Yvonne
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Nordberg, Axel
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Nyström, Daniel
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Bifunctional Dendrimers: From Robust Synthesis and Accelerated One-Pot Postfunctionalization Strategy to Potential Applications2009In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 48, no 12, p. 2126-2130Article in journal (Refereed)
  • 61.
    Aodah, Anwar
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Öcüt, Bora
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Agilt regressionssystemtest2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete utfördes på avdelningsnivån CCS på avdelningen PDU Platforms på Ericsson. Avdelningen ville förändra sin nuvarande arbetsprocess genom att övergå från Daily Build, att bygga och testa en gång om dagen, till ett mer kontinuerligt byggande och testande. CCS hanterar och tillhandahåller kontrollsystemtjänster för RNC applikationer och äldre RBS.

     

    Målet med detta examensarbete var att automatisera testprocesser för att kunna utföra kontinuerliga tester. Första steget i arbetet var att ta fram ett specifikt användningsfall, ett use case, att arbeta mot. Detta skedde genom analys av felrapporter och detta ledde till att nodomstarter definierades som ett första användningsfall. När användningsfallet var definierat, skedde analys av plattform att använda för automatisering, samt vilka steg som behövde automatiseras. De var enligt följande, uppladdning med ftp, exekvering av filer med Telnet och nodkonfiguration med verktyget Cicc.

  • 62.
    Aronson, Eran
    KTH, School of Technology and Health (STH), Design, Work Environment, Safety and Health, DASH.
    Research Project: Lighting Häggvik Tunnel, Sollentuna2013Report (Other academic)
    Abstract [en]

    A reserch paper investigating the posibility of lowering light levels in tunnel while using LED's. Done with and for Trafikverket as part of an ongoing research regarding tunnel lighting.

  • 63.
    Aronson, Eran
    KTH, School of Technology and Health (STH).
    Visual adaptation for tunnel entrance2013Report (Other academic)
    Abstract [en]

    A research report done by the lighting laboratory at KTH STH for Trafikverket. The report is presenting a second stage of tunnel lighting research, focusing on the tunnel entrance zone, where improvements to existing recommendations are suggested.

  • 64. Aronsson, Gunnar
    et al.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Ergonomics.
    Randle, Hanne
    Svensson, Lennart
    Inte bara här och nu utan också där och då: Reflektioner om arbetslivsforskningen och det stora hållbarhetsprojektet2009In: Arbetslivsforskning och hållbarhet: Arbetsliv i omvandling / [ed] I: Porsfelt, Växjö: Växjö universitet , 2009, 1Chapter in book (Other academic)
  • 65.
    Arroyo Porras, Igor Alfredo
    KTH, School of Technology and Health (STH).
    Developing an sleep scorer by using Biosignals in Matlab.: Evaluation for sleep apnea patients.2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays, sleep disorders e.g. sleep apnea —the cessation of airflow at the nose and mouth lasting at least 10 second— are a broadly problem around the world. Direct and indirect costs associated to sleep problems are outsize and the quality of patient life is deteriorated because of it. In addition, Sleep is a fundamental part of everyday life, the lack of it or the poor quality of sleep may lead into the development of important diseases. Sleep studies are usually carried out by specialists by means of polysomnography. Polysomnography is a type of sleep study which is consisting of EEG, EOG, EMG, ECG, respiratory signals and/or many other biosignals which together can be used to determine the state of patient’s sleep and any other issue. Nowadays, visual inspection of these signals forms the “gold standard” in sleep clinics. The cost of monitoring a person overnight, the scarcity of beds available and the uncertainty of whether the results are representative of a normal nights’ sleep means that a move to home diagnostics is likely to be advantageous. Therefore, a necessity for home recorders systems capable of perform this kind of analysis has come out. A state machine based automatic scorer is developed and evaluated in Matlab by using 12 recordings of apnoeic patients from sleep heart health study (SHHS) database. By the analysis of EEG, EOG, EMG, Oxygen saturation (Sao2) and respiratory movements signals, the implemented algorithm is trained and evaluated to detect the five stages of subject’s sleep (Wake, N1, N2, N3, or REM) as well as apnoeic episodes according to guidelines from American Academy of Sleep Medicine (AASM). In the final evaluation of algorithms, the automatic scorer achieved 74±5.27% accuracy for all five stages and Cohen’s kappa of 0.5 for the overall set of 12 patients, being the accuracy better for healthier subjects and reaching in this case 78±4.05%. The analysis of the sleep apnea concluded with a sensitivity of 47.08%, a specificity of 83.38%, and an accuracy of 78.1%. Differences in the performance among patients according to their apnea/hypopnea index were significant.

     

    Key Words: Polysomnography, AASM, Sleep apnea/hypopnea.

  • 66.
    Ashfaq, Awais
    KTH, School of Technology and Health (STH).
    Segmentation of Cone Beam CT in Stereotactic Radiosurgery2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    C-arm Cone Beam CT (CBCT) systems – due to compact size, flexible geometry and low radiation exposure – inaugurated the era of on-board 3D image guidance in therapeutic and surgical procedures. Leksell Gamma Knife Icon by Elekta introduced an integrated CBCT system to determine patient position prior to surgical session, thus advancing to a paradigm shift in facilitating frameless stereotactic radiosurgeries. While CBCT offers a quick imaging facility with high spatial accuracy, the quantitative values tend to be distorted due to various physics based artifacts such as scatter, beam hardening and cone beam effect. Several 3D reconstruction algorithms targeting these artifacts involve an accurate and fast segmentation of craniofacial CBCT images into air, tissue and bone.

    The objective of the thesis is to investigate the performance of deep learning based convolutional neural networks (CNN) in relation to conventional image processing and machine learning algorithms in segmenting CBCT images. CBCT data for training and testing procedures was provided by Elekta. A framework of segmentation algorithms including multilevel automatic thresholding, fuzzy clustering, multilayer perceptron and CNN is developed and tested against pre-defined evaluation metrics carrying pixel-wise prediction accuracy, statistical tests and execution times among others. CNN has proven its ability to outperform other segmentation algorithms throughout the evaluation metrics except for execution times. Mean segmentation error for CNN is found to be 0.4% with a standard deviation of 0.07%, followed by fuzzy clustering with mean segmentation error of 0.8% and a standard deviation of 0.12%. CNN based segmentation takes 500s compared to multilevel thresholding which requires ~1s on similar sized CBCT image.

    The present work demonstrates the ability of CNN in handling artifacts and noise in CBCT images and maintaining a high semantic segmentation performance. However, further efforts targeting CNN execution speed are required to utilize the segmentation framework within real-time 3D reconstruction algorithms.

  • 67.
    Asplund, Maria
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Conjugated Polymers for Neural Interfaces: Prospects, possibilities and future challenges2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Within the field of neuroprosthetics the possibility to use implanted electrodes for communication with the nervous system is explored. Much effort is put into the material aspects of the electrode implant to increase charge injection capacity, suppress foreign body response and build micro sized electrode arrays allowing close contact with neurons. Conducting polymers, in particular poly(3,4-ethylene dioxythiophene) (PEDOT), have been suggested as materials highly interesting for such neural communication electrodes. The possibility to tailor the material both mechanically and biochemically to suit specific applications, is a substantial benefit with polymers when compared to metals. PEDOT also have hybrid charge transfer properties, including both electronic and ionic conduction, which allow for highly efficient charge injection.

     

    Part of this thesis describes a method of tailoring PEDOT through exchanging the counter ion used in electropolymerisation process. Commonly used surfactants can thereby be excluded and instead, different biomolecules can be incorporated into the polymer. The electrochemical characteristics of the polymer film depend on the ion. PEDOT electropolymerised with heparin was here determined to have the most advantageous properties. In vitro methods were applied to confirm non-cytotoxicity of the formed PEDOT:biomolecular composites. In addition, biocompatibility was affirmed for PEDOT:heparin by evaluation of inflammatory response and neuron density when implanted in rodent cortex.

     

    One advantage with PEDOT often stated, is its high stability compared to other conducting polymers. A battery of tests simulating the biological environment was therefore applied to investigate this stability, and especially the influence of the incorporated heparin. These tests showed that there was a decline in the electroactivity of PEDOT over time. This also applied in phosphate buffered saline at body temperature and in the absence of other stressors. The time course of degradation also differed depending on whether the counter ion was the surfactant polystyrene sulphonate or heparin, with a slightly better stability for the former.

     

    One possibility with PEDOT, often overlooked for biological applications, is the use of its semi conducting properties in order to include logic functions in the implant. This thesis presents the concept of using PEDOT electrochemical transistors to construct textile electrode arrays with in-built multiplexing. Using the electrolyte mediated interaction between adjacent PEDOT coated fibres to switch the polymer coat between conducting and non conducting states, then transistor function can be included in the conducting textile. Analogue circuit simulations based on experimentally found transistor characteristics proved the feasibility of these textile arrays. Developments of better polymer coatings, electrolytes and encapsulation techniques for this technology, were also identified to be essential steps in order to make these devices truly useful.

     

    In summary, this work shows the potential of PEDOT to improve neural interfaces in several ways. Some weaknesses of the polymer and the polymer electronics are presented and this, together with the epidemiological data, should point in the direction for future studies within this field.

  • 68.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Hamedi, Mahiar
    Forchheimer, Robert
    Inganäs, Olle
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Wire electronics and woven logic, as a potential technology for neuroelectronic implantsManuscript (Other (popular science, discussion, etc.))
    Abstract [en]

    New strategies to improve neuron coupling to neuroelectronic implants are needed. In particular, to maintain functional coupling between implant and neurons, foreign body response like encapsulation must me minimized. Apart from modifying materials to mitigate encapsulation it has been shown that with extremely thin structures, encapsulation will be less pronounced. We here utilize wire electrochemical transistors (WECTs) using conducting polymer coated fibers. Monofilaments down to 10 μm can be successfully coated and weaved into complex networks with built in logic functions, so called textile logic. Such systems can control signal patterns at a large number of electrode terminals from a few addressing fibres. Not only is fibre size in the range where less encapsulation is expected but textiles are known to make successful implants because of their soft and flexible mechanical properties. Further, textile fabrication provides versatility and even three dimensional networks are possible. Three possible architectures for neuroelectronic systems are discussed. WECTs are sensitive to dehydration and materials for better durability or improved encapsulation is needed for stable performance in biological environments.

  • 69.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Hamedi, Mahiar
    Inganäs, Olle
    Forchheimer, Robert
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Neural microcontacts with wire electrodes and woven logic2007Conference paper (Refereed)
  • 70.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Thaning, Elin
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Lundberg, Johan
    Sandberg-Nordqvist, Ann-Christin
    Kostyszyn, Beata
    Inganäs, Olle
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Biocompatibility of PEDOT/biomolecular composites intended for neural communication electrodesManuscript (Other (popular science, discussion, etc.))
    Abstract [en]

    Electrodes of the conjugated polymer poly(3,4-ethylene dioxythiophene) (PEDOT) have been shown to possess very attractive electrochemical properties for functional electrical stimulation (FES) or recording in the nervous system. Biomolecules already present in nervous tissue, added as counter ions in PEDOT electropolymerisation, could be a route to further improve the biomaterial properties of PEDOT, eliminating the need of surfactant counter ions like docedyl benzene sulphonate (DBS) or polystyrene sulphonate (PSS) in the polymerisation process. Such PEDOT/biomolecular composites using heparin, or hyaluronic acid, have been electrochemically investigated in a previous study and have been shown to retain the attractive electrochemical properties already proven for PEDOT:PSS.

     

    The aim of the present study is to evaluate biocompatibility of these PEDOT/biomolecular composites in vitro and also evaluate PEDOT:heparin biocompatibility in cortical tissue in vivo. Hereby, we also aim to identify a suitable test protocol, that can be used in future evaluations when further material developments are made.

     

    Material toxicity was first tested on cell lines, both through a standardised agarose overlay assay on L929 fibroblasts, and through elution tests on human neuroblastoma SH-SY5Y cells. Subsequently, a biocompatibility in vivo test was performed using PEDOT:heparin coated platinum probes implanted in the cerebral cortex of Sprague-Dawley rats. Tissue was collected at three weeks and six weeks of implantation and evaluated by immunohistochemistry.

     

    No cytotoxic response was seen to any of the PEDOT:biomolecular composites tested here. Furthermore, elution tests were found to be a practical and effective way of screening materials for toxicity and had a clear advantage over the agarose overlay assay, which was difficult to apply on other cell types than fibroblasts. Elution tests would therefore be recommendable as a screening method, at all stages of material development. In the in vivo tests, the stiffness of the platinum substrate was a significant problem, and extensive glial scarring was seen in most cases irrespective of implant material. However, quantification of immunological response through distance measurements from implant site to closest neuron, and counting of macrophage densities in proximity to polymer surface, was comparable to those of platinum controls. These results indicate that PEDOT:heparin surfaces were as compatible with cortical tissue as pure platinum controls.

  • 71.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Inganäs, Olle
    Composite biomolecule/PEDOT materials for neural electrodes2008In: Biointerphases, ISSN 1559-4106, Vol. 3, no 3, p. 83-93Article in journal (Refereed)
    Abstract [en]

    Electrodes intended for neural communication must be designed to meet boththe electrochemical and biological requirements essential for long term functionality. Metallic electrode materials have been found inadequate to meet theserequirements and therefore conducting polymers for neural electrodes have emergedas a field of interest. One clear advantage with polymerelectrodes is the possibility to tailor the material to haveoptimal biomechanical and chemical properties for certain applications. To identifyand evaluate new materials for neural communication electrodes, three chargedbiomolecules, fibrinogen, hyaluronic acid (HA), and heparin are used ascounterions in the electrochemical polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). The resultingmaterial is evaluated electrochemically and the amount of exposed biomoleculeon the surface is quantified. PEDOT:biomolecule surfaces are also studiedwith static contact angle measurements as well as scanning electronmicroscopy and compared to surfaces of PEDOT electrochemically deposited withsurfactant counterion polystyrene sulphonate (PSS). Electrochemical measurements show that PEDOT:heparinand PEDOT:HA, both have the electrochemical properties required for neuralelectrodes, and PEDOT:heparin also compares well to PEDOT:PSS. PEDOT:fibrinogen isfound less suitable as neural electrode material.

  • 72.
    Atefi, Seyed Reza
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Electrical Bioimpedance Cerebral Monitoring: From Hypothesis and Simulation to First Experimental Evidence in Stroke Patients2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Stroke is amongthe leading causes of death worldwide and requires immediate care to prevent death or permanent disability. Unfortunately, the current stateof stroke diagnosis is limited to fixed neuroimaging facilities that do not allow rapid stroke diagnosis. Hence, a portable stroke-diagnosis device could assist in the pre-hospital triage of patients. Moreover, such a portable device could also be useful for bedside stroke monitoring of patients in the Neuro Intensive Care Unit (Neuro-ICU) to avoid unnecessary neuroimaging. Recent animal studies and numerical simulations have supported the idea of implementing Electrical Bioimpedance (EBI) in a portable device, allowing non-invasive assessment as a useful tool for the pre-hospital triage of stroke and Traumatic Brain Injury (TBI) patients. Unfortunately, these studies have not reported any results from human subjects in the acute phase of the stroke. The numerical simulations are also based on simple models that sometimes lack necessary details.

    Finite Element Method (FEM) simulations on a realistic numerical head model as well as experimental Bioimpedance Spectroscopy (BIS) measurements from human subjectsin the acute, subacute and chronic phasesof stroke were used to answer the following research questions: (i) Does stroke modify the electrical properties of brain tissue in a way that is detectable via EBI? (ii) Would it be possible to detect stroke via EBI as early as in the acute and sub-acute phase?(iii) Is EBI sensitive enough to monitor changes caused by stroke pathogenesis?

    Using FEM to simulate electrical current injection on the head and study the resulting distribution of electrical potential on the scalp, it was shown that Intra-Cranial Hemorrhage (ICH) affects the quasi-symmetric scalp potential distribution,creating larger left-right potential asymmetry when compared to the healthy head model. Proof-of-concept FEM simulations were also tested in a small cohort of 6ICH patients and 10 healthy controls, showing that the left-right potential difference in the patients is significantly (p<0.05) larger than in the controls. Using bioimpedance measurements in the acute,  subacute and chronic phasesof stroke and examining simple features, it was also shown that the head EBI measurements of patients suffering stroke are different from controls, enabling the discrimination of healthy controls and stroke patients at any stage of the stroke. The absolute change in test-retest resistance measurements of the control group (~5.33%) was also found to be significantly (p<0.05) smaller than the EBI measurements of patients obtained 24 hours and 72 hours after stroke onset (20.44%). These results suggested that scalp EBI is sensitive to stroke pathogenesis changesand thususeful for bedside monitoring in the Neuro-ICU. These results suggested that EBI is a potentially useful tool for stroke diagnosis and monitoring.

    Finally, the initial observations based on a small number of patients, addressing the proposed future work of this thesis, suggested that the average head resistance amplitude of hemorrhagic stroke patients is smaller than in healthy controls, while ischemic stroke patients show a larger resistance amplitude than the controls. Scalp potential asymmetry analysis of healthy, hemorrhagic and ischemic stroke subjects also suggests that these three groups can be separated. However, these results are based on a small number of patients and need to be validated using a larger cohort. Initial observations also showed that the resistance of the EBI measurements of controls is robust between test and retest measurements, showing no significant difference (less than 2% and p>0.05). Subject position during EBI recording (supine or sitting) did not seem to affect the resistance of the EBI measurements (p>0.05). However, age, sex and head size showed significant effects on the resistance measurements. These initial observations are encouraging for further research on EBI for cerebral monitoring and stroke diagnosis. However, at this stage, considering the uncertainties in stroke type differentiation, EBI cannot replace CT but has the potential to be used as a consultation tool.

  • 73.
    Atefi, Seyed Reza
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Buendia, Ruben
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Cole Function and Conductance-Based Parasitic Capacitance Compensation for Cerebral Electrical Bioimpedance Measurements2012In: Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE, San Diego: IEEE press , 2012, p. 3368-3371Conference paper (Refereed)
    Abstract [en]

    One of the most common measurement artifacts present in Electrical Bioimpedance Spectroscopy measurements (EBIS) comes from the capacitive leakage effect resulting from parasitic stray capacitances. This artifact produces a deviation in the measured impedance spectrum that is most noticeable at higher frequencies. The artifact taints the spectroscopy measurement increasing the difficulty of producing reliable EBIS measurements at high frequencies. In this work, an approach for removing such capacitive influence from the spectral measurement is presented making use of a novel method to estimate the value of the parasitic capacitance equivalent that causes the measurement artifact. The proposed method has been tested and validated theoretically and experimentally and it gives a more accurate estimation of the value of the parasitic capacitance than the previous methods. Once a reliable value of parasitic capacitance has been estimated the capacitive influence can be easily compensated in the EBIS measured data. Thus enabling analysis of EBIS data at higher frequencies, i.e. in the range of 300-500 kHz like measurements intended for cerebral monitoring, where the characteristic frequency is remarkably higher than EBIS measurements i.e. within the range 30 to 50 kHz, intended for body composition assessment.

  • 74.
    Atefi, Seyed Reza
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Kamalian, Shervin
    Rosenthal, Eric
    Lev, Michael
    Bonmassar, Giorgio
    Intracranial haemorrhage alters scalp potential distributions in bioimpedance cerebral monitoring applications: preliminary results from FEM simulation on a realistic head model and human subjects2016In: Medical Physics, ISSN 2473-4209, Vol. 43, no 2, p. 675-686Article in journal (Refereed)
    Abstract [en]

    Purpose: Current diagnostic neuroimaging for detection of intracranial hemorrhage (ICH) is limited to fixed scanners requiring patient transport and extensive infrastructure support. ICH diagnosis would therefore benefit from a portable diagnostic technology, such as electrical bioimpedance (EBI). Through simulations and patient observation, the authors assessed the influence of unilateral ICH hematomas on quasisymmetric scalp potential distributions in order to establish the feasibility of EBI technology as a potential tool for early diagnosis. Methods: Finite element method (FEM) simulations and experimental leftright hemispheric scalp potential differences of healthy and damaged brains were compared with respect to the asymmetry caused by ICH lesions on quasisymmetric scalp potential distributions. In numerical simulations, this asymmetry was measured at 25 kHz and visualized on the scalp as the normalized potential difference between the healthy and ICH damaged models. Proof-of-concept simulations were extended in a pilot study of experimental scalp potential measurements recorded between 0 and 50 kHz with the authors custom-made bioimpedance spectrometer. Mean leftright scalp potential differences recorded from the frontal, central, and parietal brain regions of ten healthy control and six patients suffering from acute/subacute ICH were compared. The observed differences were measured at the 5% level of significance using the two-sample Welch ttest. Results: The 3D-anatomically accurate FEM simulations showed that the normalized scalp potential difference between the damaged and healthy brain models is zero everywhere on the head surface, except in the vicinity of the lesion, where it can vary up to 5%. The authors preliminary experimental results also confirmed that the leftright scalp potential difference in patients with ICH (e.g., 64 mV) is significantly larger than in healthy subjects (e.g., 20.8 mV; P < 0.05). Conclusions: Realistic, proof-of-concept simulations confirmed that ICH affects quasisymmetric scalp potential distributions. Pilot clinical observations with the authors custom-made bioimpedance spectrometer also showed higher leftright potential differences in the presence of ICH, similar to those of their simulations, that may help to distinguish healthy subjects from ICH patients. Although these pilot clinical observations are in agreement with the computer simulations, the small sample size of this study lacks statistical power to exclude the influence of other possible confounders such as age, ex, and electrode positioning. The agreement with previously published simulation-based and clinical results, however, suggests that EBI technology may be potentially useful for ICH detection. © 2016 American Association of Physicists in Medicine.

  • 75.
    Atefi, Seyed Reza
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Electrical Bioimpedance cerebral monitoring. Preliminary results from measurements on stroke patients2012In: Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE, IEEE , 2012, p. 126-129Conference paper (Refereed)
    Abstract [en]

    Electrical Bioimpedance Spectroscopy (EBIS) is currently used in different tissue characterization applications. In this work we aim to use EBIS to study changes in electrical properties of the cerebral tissues after an incident of hemorrhage/ischemic stroke. To do so a case-control study was conducted using six controls and three stroke cases. The preliminary results of this study show that by using Cole-based analysis on EBIS measurements and analyzing the Cole parameters R0 and R∞, it is possible to detect changes on electrical properties of cerebral tissue after stroke. 

  • 76.
    Atefi, Seyed Reza
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Study of the dynamics of transcephalic cerebral impedance data during cardio-vascular surgery2013In: XV International Conference on Electrical Bio-Impedance (ICEBI) & XIV Conference on Electrical Impedance Tomography (EIT), Institute of Physics (IOP), 2013, Vol. 434, no 1, p. 012045-Conference paper (Refereed)
    Abstract [en]

    Postoperative neurological deficits are one of the risks associated with cardio vascular surgery, necessitating development of new techniques for cerebral monitoring. In this study an experimental observation regarding the dynamics of transcephalic Electrical Bioimpedance (EBI) in patients undergoing cardiac surgery with and without extracorporeal circulation (ECC) was conducted to investigate the potential use of electrical Bioimpedance for cerebral monitoring in cardio vascular surgery. Tetrapolar transcephalic EBI measurements at single frequency of 50 kHz were recorded prior to and during cardio vascular surgery. The obtained results show that the transcephalic impedance decreases in both groups of patients as operation starts, however slight differences in these two groups were also observed with the cerebral impedance reduction in patients having no ECC being less common and not as pronounced as in the ECC group. Changes in the cerebral impedance were in agreement with changes of haematocrit and temperature. The origin of EBI changes is still unexplained however these results encourage us to continue investigating the application of electrical bioimpedance cerebral monitoring clinically.

  • 77.
    Atefi, Seyed Reza
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Thorlin, Thorleif
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Stroke Damage Detection Using Classification Trees on Electrical Bioimpedance Cerebral Spectroscopy Measurements2013In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 13, no 8, p. 10074-10086Article in journal (Refereed)
    Abstract [en]

    After cancer and cardio-vascular disease, stroke is the third greatest cause of death worldwide. Given the limitations of the current imaging technologies used for stroke diagnosis, the need for portable non-invasive and less expensive diagnostic tools is crucial. Previous studies have suggested that electrical bioimpedance (EBI) measurements from the head might contain useful clinical information related to changes produced in the cerebral tissue after the onset of stroke. In this study, we recorded 720 EBI Spectroscopy (EBIS) measurements from two different head regions of 18 hemispheres of nine subjects. Three of these subjects had suffered a unilateral haemorrhagic stroke. A number of features based on structural and intrinsic frequency-dependent properties of the cerebral tissue were extracted. These features were then fed into a classification tree. The results show that a full classification of damaged and undamaged cerebral tissue was achieved after three hierarchical classification steps. Lastly, the performance of the classification tree was assessed using Leave-One-Out Cross Validation (LOO-CV). Despite the fact that the results of this study are limited to a small database, and the observations obtained must be verified further with a larger cohort of patients, these findings confirm that EBI measurements contain useful information for assessing on the health of brain tissue after stroke and supports the hypothesis that classification features based on Cole parameters, spectral information and the geometry of EBIS measurements are useful to differentiate between healthy and stroke damaged brain tissue.

  • 78.
    Axelsson, Pelle
    et al.
    KTH, School of Technology and Health (STH).
    Torelm, Marcus
    KTH, School of Technology and Health (STH).
    Cost-benefit-analys av optisk 3D-scanner2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 79.
    Ayas, Ebru
    KTH, School of Technology and Health (STH), Ergonomics.
    Engineering Quality Feelings: Applications in products, service environments and work systems2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Contemporary quality issues in product design are moving from materialistic to emotional user fulfillment; comprehensive research is needed to examine quality product feelings. This research is directed toward a deeper understanding of user and customer quality feelings for different product types, including services.

    The quality feelings concept includes dimensions of product quality, especially functionality, ergonomics and aesthetics. The first objective of this thesis is to identify, prioritize and synthesize quality feelings into product attributes in product development applications. The second objective is to explore, test and propose methodological approaches for designing quality feelings into products.

    Several methods from psychology, ergonomics, statistics and probabilistic methods and heuristics were applied to achieve the objectives. From a methodological viewpoint, Likert scales, free elicitation technique and Just About Right scales were applied for data collection. Multiple Regression, Factor Analysis, Correspondence Analysis, Genetic algorithms, Partial Least Squares (PLS) and Rough Sets (RS) were applied for data analyses. For ergonomic product evaluations, direct observations, 3D workload simulations, time and frequency analyses were conducted.

    Five product applications are included in this thesis: operator driver cabin design of reach trucks, steering wheel design trigger switch design in right-angled nutrunners, bed-making systemsproducts and waiting room environments.

    Heuristic methods were found effective when there is a high number of product attributes that interact to provide quality feelings. RS results are consistent with PLS attribute predictions. When the number of product attributes is large in comparison to the number of observations, PLS extracts informative results for quality feelings. The RS method is effective in identifying interactions among design attributes.

    Quality feelings are associated with both tangible (tactile characteristics) and intangible (quick and easy to use) product characteristics. Words such as safety, functionality, ergonomics, comfort, reliability, supportiveness, usability, feedback, pleasantness, attractiveness, durability and distinctiveness describe quality feelings from tangible products and services. Based on product type, the quality dimensions represented by these words possess different interactions and dependencies. In work environments, products act as prostheses between workers for social interaction, which need to be considered as important quality feelings dimensions.

  • 80.
    Ayas, Ebru
    et al.
    KTH, School of Technology and Health (STH), Ergonomics.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Ergonomics.
    An Affective Engineering Assessment of a Hospital Bedding System Innovation2011In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126Article in journal (Other academic)
    Abstract [en]

    Developing bedding products requires consideration of human-product interactions such as usability and quality aspects besides ergonomics and productivity. Previous studies focus on finding associations between discomfort evaluations and physiological measurements of conventional bedding. The purpose of this study is to assess a new bedding system by observing affective and discomfort perceptions, physical loads, and time usage by nursing personnel. Fourteen nursese valuated a conventional and a new bedding system. Results suggest that nurses’ quality perceptions and overall experiences with the new bedding were positive. Considering physical loads the average time and frequency of bending forward were significantly lower for the new bedding versus conventional bedding. The time analysis yielded significant improvements to make a bed with the new bedmaking system. Quality perceptions were associated with tactile qualities (e.g. soft, nice to touch, etc.) and applicability (e.g. quick setup) for both bedmaking systems.

  • 81.
    Ayas, Ebru
    et al.
    Linköping University.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Ergonomics.
    Ishihara, Shigekazu
    Affective Design of Waiting Areas in Primary Healthcare2008Article in journal (Refereed)
    Abstract [en]

    Purpose – This paper seeks to deal with affective design of waiting areas (servicescapes) and has twofold aims. The first, is to explore affective values for waiting areas. The second, is to identify interactions between physical design attributes and affective values.

    Design/methodology/approach – This study included a free association method for data collection, applying Kansei engineering methodology to extract design solutions relating to specific feelings. The study was undertaken at six primary health centres in Östergötland County, Sweden. In total, 88 participants (60 patients and 28 staff) were interviewed.

    Findings – The selected waiting areas show significant differences for their perceived affective qualities. The most desired feeling for creating affective values is found to be “calm”. The core design attributes contributing to this feeling are privacy, colours, child play-areas and green plants. Good design of lighting, seating arrangements and a low sound level are also important design attributes to give a more complete design solution.

    Research limitations/implications – The study provides useful insights for understanding affective needs in servicescapes, and it provides design suggestions. The results have not been analysed separately for gender or different age groups.

    Practical implications – The paper proposes a framework model to be applied when dealing with affective values in servicescapes.

    Originality/value – This paper makes an original contribution to understand affective values towards the physical environment in servicescape design. It offers a methodology to study complex environments with many alternative design solutions using limited resources. Moreover, this study uses a combination of a free association method and Rough Sets theory in affective design.

  • 82.
    Ayas, Ebru
    et al.
    KTH, School of Technology and Health (STH), Ergonomics.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Ergonomics.
    Ishihara, Shigekazu
    Affective engineering evaluation of non-linear trigger switch mechanisms2011In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126Article in journal (Other academic)
    Abstract [en]

    The trigger switch mechanisms of nutrunners are important for operators to perceive feedback while tightening bolt joints. Previous studies focus on associations between discomfort evaluations and powered tool operation. This paper addresses how operator preferences are linked with functionality requirements from trigger switch mechanisms. Subjects evaluated five switch mechanism prototypes regarding perceptions of quality, feedback, firmness, and distinctness. Results suggest that loading and unloading phases of trigger operation are significant predictors of perceptions of quality. The trigger switch mechanism with a combination of high peak-drop-bottom forces was perceived with better quality, feedback, and distinctness in comparison to the other mechanisms. The study also revealed that when the switch mechanism was designed to give more distinctness and feedback, higher quality is perceived.

  • 83.
    Ayas, Ebru
    et al.
    KTH, School of Technology and Health (STH), Ergonomics.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Ergonomics.
    Ishihara, Shigekazu
    An Analysis on Affective Design of Servicescapes2009In: Proceedings of 12 th QMOD and Toulon-Verona Conference on Quality and Service Sciences, 2009Conference paper (Refereed)
  • 84.
    Ayas, Ebru
    et al.
    KTH, School of Technology and Health (STH), Ergonomics.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Ergonomics.
    Ishihara, Shigekazu
    Kansei/Affective Engineering Applied to Triggers in Powered Tools2011In: Kansei/Affective Engineering / [ed] Nagamachi, Mitsuo, CRC , 2011, p. 275-293Chapter in book (Refereed)
  • 85.
    Ayas, Ebru
    et al.
    KTH, School of Technology and Health (STH), Ergonomics.
    Jörgen, Eklund
    KTH, School of Technology and Health (STH), Ergonomics.
    Identifying trigger feeling factors2010In: International Conference on Kansei Engineeringand Emotional Research (KEER), Paris, France, 2010Conference paper (Refereed)
    Abstract [en]

    Trigger mechanism design in power hand tools is of great importance for communicating with the operator and for providing feedback on operational functioning. Therefore, for a successful power hand tool design, knowledge about how the trigger mechanism feels is required.

    This study aims to define and investigate the design factors related with trigger tactile feeling for electrical right angled nutrunners. A Kansei Engineering (Affective Engineering) study has been conducted for a comparison between users´ (operators that work at an automotive assembly plant) and product developers´ (product development group of a power hand tool manufacturer) to find common and differing semantic expression dimensions for that. 124 Kansei words (descriptors) were collected from literature, interviews and workshops. These words were reduced to 52 by affinity analysis and evaluated by operators and product developers using semantic differential technique.

    From the operator group`s responses six factors (explain 87% of variation ) were extracted as, “professional performance”, “safety and tactile feeling”, “usability”, “smooth operation”, ”communication and durability”, “convenient and comfortable” to define trigger feeling. Correspondingly, five factors (explain 89% of variation) “robust and appealing”, “ergonomics and operator performance”, “controllability and predictability”, “creativity and modern” and“powerful” were distinguished for the product development group. Results showed that the start phase and especially quick start of trigger mechanism is more important to operators, while end feedback is more important to product developers. Soft start of the trigger is correlated with ergonomics, optimal, clear operation and performance for product developers while soft start together with end feedback are associated with well-built, convenient and safe trigger characteristics for operators. According to the results from average ratings the Kansei word “ergonomic” has been rated as the most important descriptor for trigger feeling together with “user-friendly”, “easy to use”, “long life time” and “comfortable” for both groups. By developing a questionnaire using the factors and variables identified; this questionnaire can be used to assess views of operators about trigger functioning and to know how do operators feel about new types of trigger mechanisms.

  • 86. Aydoǧan, R.
    et al.
    Lo, J. C.
    Meijer, Sebastian A.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Jonker, C. M.
    Modeling network controller decisions based upon situation awareness through agent-based negotiation2014In: 44th International Simulation and Gaming Association Conference, ISAGA 2013 and 17th IFIP WG 5.7 Workshop on Experimental Interactive Learning in Industrial Management, Springer-Verlag Tokyo Inc., 2014, p. 191-200Conference paper (Refereed)
    Abstract [en]

    The Dutch railway traffic control is in an urgent need for innovation and therefore turns to gaming simulation as a platform to test and train future configurations of the system. The presence of relevant participants is necessary to keep the fidelity of the gaming simulation high. Network controllers are often needed in such games, but are expensive, scarce, and often have limited action, thus making their involvement less than desirable. To overcome this, the current paper introduces the use of intelligent software agents to replace some roles. The cognitive construct of situation awareness is required to model the evaluation of an offer in a negotiation setting, in which a situation awareness model (SAM) is introduced for evaluating offers in complex and dynamic systems.

  • 87.
    Ayele, Yohannes Haileyesus
    KTH, School of Technology and Health (STH).
    Region-Based Contrast Transfer Function correction for Electron Microscopy Images2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Electron crystallography is one of the methods for determining the structure of membrane proteins. However, the resolution that we get from electron crystallography of membrane proteins is limited by crystal disorder and inaccurate determination of contrast transfer function (CTF) parameters. To overcome these problems, we applied single particle refinement with local averaging for long range variation of the crystals and local region-based CTF correction for the tilted images. These two corrections are done on the Melibiose Permease (MelB) data sets and a resolution of 8.6Å is reported.

  • 88. Ayllnon, David
    et al.
    Gil-Pita, Roberto
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Detection and Classification of Measurement Errors in Bioimpedance Spectroscopy2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 6, article id e0156522Article in journal (Refereed)
    Abstract [en]

    Bioimpedance spectroscopy (BIS) measurement errors may be caused by parasitic stray capacitance, impedance mismatch, cross-talking or their very likely combination. An accurate detection and identification is of extreme importance for further analysis because in some cases and for some applications, certain measurement artifacts can be corrected, minimized or even avoided. In this paper we present a robust method to detect the presence of measurement artifacts and identify what kind of measurement error is present in BIS measurements. The method is based on supervised machine learning and uses a novel set of generalist features for measurement characterization in different immittance planes. Experimental validation has been carried out using a database of complex spectra BIS measurements obtained from different BIS applications and containing six different types of errors, as well as error-free measurements. The method obtained a low classification error (0.33%) and has shown good generalization. Since both the features and the classification schema are relatively simple, the implementation of this pre-processing task in the current hardware of bioimpedance spectrometers is possible.

  • 89.
    Ayllon, David
    et al.
    Department of Signal Theory and Communications.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Gil-Pita, Roberto
    Department of Signal Theory and Communications.
    Cole equation and parameter estimation from electrical bioimpedance spectroscopy measurements: A comparative study2009In: EMBC: 2009 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-20, Buenos Aires: IEEE Engineering in Medicine and Biology , 2009, p. 3779-3782Conference paper (Refereed)
    Abstract [en]

    Since there are several applications of Electrical Bioimpedance (EBI) that use the Cole parameters as base of the analysis, to fit EBI measured data onto the Cole equation is a very common practice within Multifrequency-EBI and spectroscopy. The aim of this paper is to compare different fitting methods for EBI data in order to evaluate their suitability to fit the Cole equation and estimate the Cole parameters. Three of the studied fittings are based on the use of Non-Linear Least Squares on the Cole model, one using the real part only, a second using the imaginary part and the third using the complex impedance. Furthermore, a novel fitting method done on the impedance plane, without using any frequency information has been implemented and included in the comparison. Results show that the four methods perform relatively well but the best fitting in terms of standard error of estimate is the fitting obtained from the resistance only. The results support the possibility of measuring only the resistive part of the bioimpedance to accurately fit Cole equation and estimate the Cole parameters, with entailed advantages.

  • 90. Azar, J.C.
    et al.
    Hamid Muhammed, Hamed
    KTH, School of Technology and Health (STH), Medical Engineering.
    Automated Tracking of the Carotid Artery in Ultrasound Image Sequences Using a Self Organizing Neural Network2010In: Proceedings of 20th International Conference on Pattern Recognition (ICPR 2010), Istanbul, Turkey, Istanbul, Turkey, 2010, p. 2548-2551Conference paper (Refereed)
    Abstract [en]

    An automated method for the segmentation and tracking of moving vessel walls in 2D ultrasound image sequences is introduced. The method was tested on simulated and real ultrasound image sequences of the carotid artery. Tracking was achieved via a self organizing neural network known as Growing Neural Gas. This topology-preserving algorithm assigns a net of nodes connected by edges that distributes itself within the vessel walls and adapts to changes in topology with time. The movement of the nodes was analyzed to uncover the dynamics of the vessel wall. By this way, radial and longitudinal strain and strain rates have been estimated. Finally, wave intensity signals were computed from these measurements. The method proposed improves upon wave intensity wall analysis, WIWA, and opens up a possibility for easy and efficient analysis and diagnosis of vascular disease through noninvasive ultrasonic examination.

  • 91.
    Azhari, Mohammad
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Raghothama, Jayanth
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Meijer, Sebastiaan
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    A Design and Implementation of Interactive Visualizations and Simulation in Transportation2014In: The Shift from Teaching to Learning: Individual, Collective and Organizational Learning Through Gaming Simulation: Proceedings of the 45th Conferenceof the International Simulation and Gaming Association, 2014Conference paper (Refereed)
    Abstract [en]

    Transportation Planners have a long history of using Geographical Information Systems, Simulation Models and Visualizations for decision support. A frame-work that integrates all three can provide enhanced decision support, opportuni-ties for training and planning future scenarios. In the current paper, we describe the concept of such a framework and the first steps toward its development.

  • 92.
    Baitar, Rami
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Riskanalys av elsystem med funktions-FMEA2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The risk analysis tool failure mode and effects analysis (FMEA) that analyzes the com-ponents and signals of a electrical system is design dependent and are therefore per-formed late in the development process of electrical systems. This could lead to that some errors are not analyzed in time and may need to be designed away which can lead to increased system complexity as well as longer and more expensive development proc-esses.The objective of this study is that through a literature review identify if there are any methods or approaches that enables Scania to implement a functional hazard analyzes early in the development process of electrical systems and to analyze these.The results of this thesis shows that it is possible to start the FMEA process early in the development process of the electrical system if the engineers have a functional perspec-tive in mind when performing the risk analysis where they list and rank the functions that is provided by the electrical system and their failure modes, failure effects, failure de-tection, severity, probability and occurrence.By using a function based FMEA, the engineer(s) can identify and promptly handle the safety critical functions early in the development process of a electrical system.A existing functionality at Scania has been broken down into functions and a functional hazard analysis has been performed on these as a demonstration of how a function based FMEA can be carried out and look like.

  • 93.
    Baltoglou, Georgios
    et al.
    KTH, School of Technology and Health (STH).
    Karapistoli, E.
    Chatzimisios, P.
    IPTV QoS and QoE measurements in wired and wireless networks2012In: 2012 IEEE Global Communications Conference (GLOBECOM), IEEE , 2012, p. 1757-1762Conference paper (Refereed)
    Abstract [en]

    Internet Protocol Television or IPTV is a multimedia content delivery service that is increasingly proliferating in the consumers lives and a hot-topic for telecommunication companies to gain a share on consumers' entertainment budget. This alternate method of distributing television content over IP requires a high level of network performance and guaranteed Quality of Service (QoS) in order for the end user to have an assured and high-quality viewing experience. Yet, the quality margins of IPTV are commonly put to test in almost all cases where customers re-distribute the service within their premisses. In this paper, our main motivation is to investigate how such real-life networks perform in terms of distributing this inelastic and high-bandwidth type of service utilizing traffic measurements. Furthermore, our goal is to verify and analyze whether these studied networks are well suited for multicast IPTV traffic.

  • 94.
    Baltoglou, Georgios
    et al.
    KTH, School of Technology and Health (STH).
    Karapistoli, Eirini
    Chatzimisios, Periklis
    Real-World IPTV Network Measurements2011In: 2011 IEEE SYMPOSIUM ON COMPUTERS AND COMMUNICATIONS (ISCC), 2011Conference paper (Refereed)
    Abstract [en]

    Internet Protocol Television or IPTV is defined as an alternate method of distributing television content over IP by a telecom carrier or an Internet service provider (ISP) and it is increasingly gaining market share in modern communication networks. IPTV poses specific requirements on the network infrastructure and at the same time it requires that several network performance characteristics are maintained under defined levels in order for the end user to have an assured viewing experience. In this paper, our main motivation is to investigate how a real life network performs in terms of distributing this inelastic and high-bandwidth type of service utilizing traffic measurements. Furthermore, our goal is to verify and analyze whether the studied network is suited for multicast IPTV traffic.

  • 95.
    Bassan, Gioia
    KTH, School of Technology and Health (STH).
    Dual-Probe Shear Wave Elastography in a Transversely Isotropic Phantom2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Shear Wave Elastography (SWE) is an ultrasound based technique which is able to measure tissue stiffness through the speed of induced shear waves. Tissue stiffness is often related to pathological conditions and detecting mechanical changes can help the recognition of potential diseases. The clinical use of SWE is limited to isotropic tissue due to the difficulty in assessing a theoretical model for more complex tissue and this project therefore aimed to evaluate the possibility of obtaining a full mechanical characterization of a transversely isotropic (TI) phantom with dual-probe SWE. A TI hydrogel phantom was developed and mechanical tests were performed to verify its anisotropy and determine the elastic moduli in both the perpendicular and longitudinal directions. Shear moduli were estimated using conventional and dual-probe SWE comparing the results to theoretical pure-transverse (PT) and quasi-transverse (QT) wave propagation modes. Both mechanical and SWE tests showed that the phantoms were transversely isotropic ET/EL=0.81. Moreover, multiple wave propagation modes calculated with dual-probe SWE showed a good agreement with the theoretical curves and indicated the possibility of measuring all the elasticity constants needed to fully characterize an incompressible, TI tissue with dual-probe SWE.

  • 96. Bassan, Gioia
    et al.
    Larsson, David
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Nordenfur, Tim
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Bjällmark, Anna
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Larsson, Matilda
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Acquisition of multiple mode shear wave propagation in transversely isotropic medium using dualprobe setup2015Conference paper (Refereed)
  • 97.
    Batool, Nazre
    KTH, School of Technology and Health (STH).
    Detection and Spatial Analysis of Hepatic Steatosis in Histopathology Images using Sparse Linear Models2016In: 2016 SIXTH INTERNATIONAL CONFERENCE ON IMAGE PROCESSING THEORY, TOOLS AND APPLICATIONS (IPTA), IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    Hepatic steatosis is a defining feature of nonalcoholic fatty liver disease, emerging with the increasing incidence of obesity and metabolic syndrome. The research in image-based analysis of hepatic steatosis mostly focuses on the quantification of fat in biopsy images. This work furthers the image-based analysis of hepatic steatosis by exploring the spatial characteristics of fat globules in whole slide biopsy images after performing fat detection. An algorithm based on morphological filtering and sparse linear models is presented for fat detection. Then the spatial properties of detected fat globules in relation to the hepatic anatomical structures of central veins and portal tracts are explored. The test dataset consists of 38 high resolution images from 21 patients. The experimental results provide an insight into the size distributions of fat globules and their location with respect to the anatomical structures.

  • 98.
    Baumann, Michael
    KTH, School of Technology and Health (STH).
    Performance of a Micro-CT System: Characterisation of Hamamatsu X-ray source L10951-04 and flat panel C7942CA-222014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis evaluated the performance of a micro-CT system consisting of Hamamatsu microfocus X-ray source L10951-04 and CMOS flat panel C7942CA-22. The X-ray source and flat panel have been characterised in terms of dark current, image noise and beam profile. Additionally, the micro-CT system’s spatial resolution, detector lag and detector X-ray response have been measured. Guidance for full image correction and methods for characterisation and performance test of the X-ray source and detector is presented.

    A spatial resolution of 7 lp/mm at 10 % MTF was measured. A detector lag of 0.3 % was observed after ten minutes of radiation exposure. The performance of the micro-CT system was found to be sufficient for high resolution X-ray imaging. However, the detector lag effect is strong enough to reduce image quality during subsequent image acquisition and must either be avoided or corrected for.

  • 99.
    Baumann, Michael
    et al.
    KTH, School of Technology and Health (STH).
    Damberg, Emmy
    KTH, School of Technology and Health (STH).
    Preoperativ värmning för att minska risken för hypotermi vid stor bukkirurgi: en pilotstudie2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 100. Beillas, P.
    et al.
    Petit, P.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Kirscht, S.
    Chawla, A.
    Jolivet, E.
    Faure, F.
    Praxl, N.
    Bhaskar, A.
    Specifications of a software framework to position and personalise human body models2015In: 2015 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, International Research Council on the Biomechanics of Injury , 2015, p. 594-595Conference paper (Refereed)
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