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  • 1.
    Axelberg, Peter
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    On Tracing Flicker Sources and Classification of Voltage Disturbances2007Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Developments in measurement technology, communication and data storage have resulted in measurement systems that produce large amount of data. Together with the long existing need for characterizing the performance of the power system this has resulted in demand for automatic and efficient information-extraction methods. The objective of the research work presented in this thesis was therefore to develop new robust methods that extract additional information from voltage and current measurements in power systems. This work has contributed to two specific areas of interest. The first part of the work has been the development of a measurement method that gives information how voltage flicker propagates (with respect to a monitoring point) and how to trace a flicker source. As part of this work the quantity of flicker power has been defined and integrated in a perceptionally relevant measurement method. The method has been validated by theoretical analysis, by simulations, and by two field tests (at low-voltage and at 130-kV level) with results that matched the theory. The conclusion of this part of the work is that flicker power can be used for efficient tracing of a flicker source and to determine how flicker propagates. The second part of the work has been the development of a voltage disturbance classification system based on the statistical learning theory-based Support Vector Machine method. The classification system shows always high classification accuracy when training data and test data originate from the same source. High classification accuracy is also obtained when training data originate from one power network and test data from another. The classification system shows, however, lower performance when training data is synthetic and test data originate from real power networks. It was concluded that it is possible to develop a classification system based on the Support Vector Machine method with “global settings” that can be used at any location without the need to retrain. The conclusion is that the proposed classification system works well and shows sufficiently high classification accuracy when trained on data that originate from real disturbances. However, more research activities are needed in order to generate synthetic data that have statistical characteristics close enough to real disturbances to replace actual recordings as training data.

  • 2.
    Buendia, Ruben
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Gil-Pita, Roberto
    Seoane, Fernando
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Cole Parameter Estimation from the Modulus of the Electrical Bioimpeadance for Assessment of Body Composition. A Full Spectroscopy Approach2011Inngår i: Journal of Electrical Bioimpedance, ISSN 1891-5469, E-ISSN 1891-5469, Vol. 2, s. 72-78Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Activities around applications of Electrical Bioimpedance Spectroscopy (EBIS) have proliferated in the past decade significantly. Most of these activities have been focused in the analysis of the EBIS measurements, which eventually might enable novel applications. In Body Composition Assessment (BCA), the most common analysis approach currently used in EBIS is based on the Cole function, which most often requires curve fitting. One of the most implemented approaches for obtaining the Cole parameters is performed in the impedance plane through the geometrical properties that the Cole function exhibit in such domain as depressed semi-circle. To fit the measured impedance data to a semi-circle in the impedance plane, obtaining the Cole parameters in an indirect and sequential manner has several drawbacks. Applying a Non-Linear Least Square (NLLS) iterative fitting on the spectroscopy measurement, obtains the Cole parameters considering the frequency information contained in the measurement. In this work, from experimental total right side EBIS measurements, the BCA parameters have been obtained to assess the amount and distribution of whole body fluids. The values for the BCA parameters have been obtained using values for the Cole parameters estimated with both approaches: circular fitting on the impedance plane and NLLS impedance-only fitting. The comparison of the values obtained for the BCA parameters with both methods confirms that the NLLS impedance-only is an effective alternative as Cole parameter estimation method in BCA from EBIS measurements. Using the modulus of the Cole function as the model for the fitting would eliminate the need for performing phase detection in the acquisition process, simplifying the hardware specifications of the measurement instrumentation when implementing a bioimpedance spectrometer.

  • 3. Buendia, Ruben
    et al.
    Seoane, Fernando
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Gil-Pita, Roberto
    A Novel Approach for Removing the Hook Effect Artefact from Electrical Bioimpedance Spectroscopy Measurements2009Inngår i: Journal of Physics: Conference Series, Institute of Physics Publishing Ltd. , 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Very often in Electrical Bioimpedance (EBI) spectroscopy measurements the presence of stray capacitances creates a measurement artefact commonly known as Hook Effect. Such an artefact creates a hook-alike deviation of the EBI data noticeable when representing the measurement on the impedance plane. Such Hook Effect is noticeable at high frequencies but it also causes a data deviation at lower measurement frequencies. In order to perform any accurate analysis of the EBI spectroscopy data, the influence of the Hook Effect must be removed. An established method to compensate the hook effect is the well known Td compensation, which consist on multiplying the obtained spectrum, Zmeas() by a complex exponential in the form of exp[jTd]. Such a method cannot correct entirely the Hook Effect since the hook-alike deviation occurs a broad frequency range in both magnitude and phase of the measured impedance, and by using a real value for Td. First, a real value only modifies the phase of the measured impedance and second, it can only correct the Hook Effect at a single frequency. In addition, the process to select a value for Td by an iterative process with the aim to obtain the best Cole fitting lacks solid scientific grounds. In this work the Td compensation method is revisited and a modified approach for correcting the Hook Effect that includes a novel method for selecting the correcting values is proposed. The initial validation results confirm that the proposed method entirely corrects the Hook Effect at all frequencies.

  • 4.
    Ferreira Gonzalez, Javier
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Textile-enabled Bioimpedance Instrumentation for Personalised Health Monitoring Applications2013Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    A growing number of factors, including the costs, technological advancements, an ageing population, and medical errors are leading industrialised countries to invest in research on alternative solutions to improving their health care systems and increasing patients’ life quality. Personal Health System (PHS) solutions envision the use of information and communication technologies that enable a paradigm shift from the traditional hospital-centred healthcare delivery model toward a preventive and person-centred approach. PHS offers the means to follow patient health using wearable, portable or implantable systems that offer ubiquitous, unobtrusive bio-data acquisition, allowing remote access to patient status and treatment monitoring.Electrical Bioimpedance (EBI) technology is a non-invasive, quick and relatively affordable technique that can be used for assessing and monitoring different health conditions, e.g., body composition assessments for nutrition. EBI technology combined with state-of-the-art advances in sensor and textile technology are fostering the implementation of wearable bioimpedance monitors that use functional garments for the implementation of personalised healthcare applications.This research studies the development of a portable EBI spectrometer that can use dry textile electrodes for the assessment of body composition for the purposes of clinical uses. The portable bioimpedance monitor has been developed using the latest advances in system-on-chip technology for bioimpedance spectroscopy instrumentation. The obtained portable spectrometer has been validated against commercial spectrometer that performs total body composition assessment using functional textrode garments.The development of a portable Bioimpedance spectrometer using functional garments and dry textile electrodes for body composition assessment has been shown to be a feasible option. The availability of such measurement systems bring closer the real implementation of personalised healthcare systems.

  • 5.
    Ferreira Gonzalez, Javier
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Seoane, Fernando
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Lindecrantz, Kaj
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    AD5933-Based Electrical Bioimpedance Spectrometer. Towards Textile-Enabled Applications.2011Konferansepaper (Fagfellevurdert)
  • 6.
    Guo, Li
    et al.
    Högskolan i Borås, Institutionen Textilhögskolan.
    Berglin, Lena
    Högskolan i Borås, Institutionen Textilhögskolan.
    Mattila, Heikki
    Högskolan i Borås, Institutionen Textilhögskolan.
    Textile Strain Sensors Characterization- Sensitivity, Linearity, Stability and Hysteresis2010Inngår i: Nordic Textile Journal, nr 2, s. 51-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper 4 different textile based strain sensors for measuring different level of strains were presented. Sensor consist a conductive part formed by coating or weaving technique. Both elastic and inelastic textile substrates were selected to achieve the required stains in applications. Sensor configuration was characterized using a tensile tester and measuring the resistance parallel by microprocessor. A linear working range with transfer function of each sensor was found. Coated sensor gives a good stability, while woven sensor was relative less stable. Inelastic textile substrate reduces the hysteresis error caused by refraction and construction of materials. The sensitivities were between 2.5 to 9 vary with different sensors. This paper finished by a discussion of how to choose sensors with different applications, among which sensor function and processability are most important aspects to be considering.

  • 7.
    Guo, Li
    et al.
    Högskolan i Borås, Institutionen Textilhögskolan.
    Berglin, Lena
    Högskolan i Borås, Institutionen Textilhögskolan.
    Mattila, Heikki
    Högskolan i Borås, Institutionen Textilhögskolan.
    Mehrjerdi, Adib
    Skrifvars, Mikael
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Disappearing Sensors. Textile Based Sensors for Monitoring Breathing2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Textile based sensors were developed and used for remote monitoring of breathing. The breathing is simulated by using a new cyclic tester device. In the simulated a cyclic force is applied along the length of the textile sensor. However due to the morphology of human body, in real situation the sensor is not only under stretching but also under a certain degree of bending. A prototype garment with the sensor situated on the chest area was made. The prototype was worn by 10 persons, and breathing was recorded as the persons were sitting still, walking and jogging. Deep breathing in the supine position and breathing with a method called athletic breathing were used to evaluate the sensor. A testing circuit and a Labview program were made for preliminary test. The sensor is wearable, washable and comfortable. Sensor construction is totally ‘disappearing’ and visualize as printed pattern onto the surface of garment.

  • 8.
    Seoane Martínez, Fernando
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Electrical bioimpedance cerebral monitoring2007Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Neurologically related injuries cause a similar number of deaths as cancer, and brain damage is the second commonest cause of death in the world and probably the leading cause of permanent disability. The devastating effects of most cases of brain damage could be avoided if it were detected and medical treatment initiated in time. The passive electrical properties of biological tissue have been investigated for almost a century and electrical bioimpedance studies in neurology have been performed for more than 50 years. Even considering the extensive efforts dedicated to investigating potential applications of electrical bioimpedance for brain monitoring, especially in the last 20 years, and the specifically acute need for such non-invasive and efficient diagnosis support tools, Electrical Bioimpedance technology has not made the expected breakthrough into clinical application yet. In order to reach this stage in the age of evidence-based medicine, the first essential step is to demonstrate the biophysical basis of the method under study. The present research work confirms that the cell swelling accompanying the hypoxic/ischemic injury mechanism modifies the electrical properties of brain tissue, and shows that by measuring the complex electrical bioimpedance it is possible to detect the changes resulting from brain damage. For the development of a successful monitoring method, after the vital biophysical validation it is critical to have available the proper electrical bioimpedance technology and to implement an efficient protocol of use. Electronic instrumentation is needed for broadband spectroscopy measurements of complex electrical bioimpedance; the selection of the electrode setup is crucial to obtain clinically relevant measurements, and the proper biosignal analysis and processing is the core of the diagnosis support system. This work has focused on all these aspects since they are fundamental for providing the solid medico-technological background necessary to enable the clinical usage of Electrical Bioimpedance for cerebral monitoring.

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