Dissertations / Theses on the topic 'Electrical measurent'
To see the other types of publications on this topic, follow the link: Electrical measurent.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Electrical measurent.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
South, G. "A technique for measuring the electrical impedance of mechanical joints in electrically conductive structures." Thesis, University of Central Lancashire, 1992. http://clok.uclan.ac.uk/20064/.
Full textAbstract:
The impedance of a circular coil placed above a conducting surface is calculated using three mathematical models. The first considers the interaction of the test coil with a uniform, homogeneous and electrically thick conducting sheet. The model quantifies the interaction of the coil and the surface by calculating the field around the coil in the frequency domain. The sheet is included by using reflection coefficients, calculated from defined physical properties, to modify the field components surrounding the coil. Cylindrical symmetry is used to reduce the problem to two dimensions. The second model is a finite difference solution in the frequency domain of the differential equation describing the magnetic vector potential. Cylindrical symmetry is used to reduce the problem to two dimensions. An approximation allowing a mechanical joint of finite physical dimensions to be included is described. The third model is a finite difference, time domain solution of the differential form of the field equations. This is a complete three dimensional analysis of the problem, including the effect of fasteners and sealants. An algorithm allowing the inclusion of materials with anisotropic electrical conductivity is described. Fourier analysis is used to transform the time domain results into the frequency domain. The results calculated from the three models are compared with practical measurements. Two instruments are constructed and practically evaluated. The first is suitable for frequencies up to 50kHz. It is based upon two test coils in a bridge arrangement and the effect of the joint is measured in terms of the out-of-balance bridge voltage. The second instrument is based upon the effect of the joint of interest upon the resonant frequency of a test coil, measured using a modified Q meter circuit. Frequencies up to 70MHz have been considered.
2
Stan, Nikola. "Complete Measurement System for Measuring High Voltage and Electrical Field Using Slab-Coupled Optical Fiber Sensors." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7053.
Full textAbstract:
A slab-coupled optical fiber sensor (SCOS) falls into a narrow class of all-dielectric optical fiber electric field sensors, which makes it a perfect candidate for measurements of high electric fields in environments where presence of conductors is highly perturbing to the system under test. Its nonlinear response to high fields requires a new nonlinear calibration technique. A nonlinear calibration method is explained and demonstrated to successfully measure high electric fields, as well as high voltages with dynamic range up to 50 dB. Furthermore, a SCOS can be fitted into narrow spaces and make highly localized measurements due to its small size. This allows a SCOS to be integrated inside a standard high voltage coaxial cable, such as RG-218. Effects of partial discharge and arcing is minimized by development of a fabrication method to avoid introduction of impurities, especially air-bubbles, into the cable during SCOS insertion. Low perturbation of the measured voltage is shown by simulating the introduced voltage reflections to be on the order of –50 dB. It is also shown that a SCOS can be inserted into other cables without significant perturbation to the voltage. A complete high voltage and high electric field measurement system is built based on the high-voltage modifications of the SCOS technology. The coaxial SCOS is enhanced for robustness. Enhancements include packaging a SCOS into stronger ceramic trough, strengthening the fiber with kevlar reinforced furcation tubing and protecting the sensor with metal braces and protective shells. The interrogator is protected from electromagnetic interference with an RF-shielded box. Reduction in power losses introduced by the new PANDA-SCOS technology allows interrogator bandwidths to be increased up to 1.2 GHz. The whole measurement process is streamlined with dedicated software, developed specifically for high voltage and electric field measurements with support for the nonlinear calibration.
3
Clippingdale, Andrew John. "The sensing of spatial electrical potential." Thesis, University of Sussex, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385059.
Full text
4
Miller, Stuart M. "Electrical measurement of sucrose in sugar beet." Thesis, Cranfield University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294156.
Full text
5
McAllister, Abraham Roy 1976. "Measuring electrical properties of the tectorial membrane." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80548.
Full textAbstract:
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (leaves 71-72).
by Abraham Roy McAllister.
M.Eng.
6
Schippan, Frank. "The contactless measurement of the electrical resistivity." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/14732.
Full textAbstract:
Physicists are interested in understanding the processes of nature. Within the field of Solid State Physics the characterisation of materials and the measurement of their properties is the first step towards identifiying new and interesting areas of scientific activities. The electrical resistivity of conductive materials is an important property which provides information about the electronic behaviour of the material. An elegant method to determine this characteristic is the measurement without using electrical contacts. Such a method avoids a whole set of experimental problems connected with the physics of electrical contacts to the sample. This Master-thesis gives an introduction into this experimental technique. A detailed theoretical description is developed. The experimental activity has involved the design, construction and testing of the apparatus. In the process of testing the method novel aspect emerged: The measurement at resonance point. These measurements can yield separate values for two different physical quantities: the electrical resistivity e and the magnetic susceptibility x. The innovation of this project is the simultaneous characterisation of both values for the material under investigation. The report starts by giving the theoretical background within which the first part of the detailed theoretical predictions are discussed. The second part contains experiments and a description of the experimental set-up. This design is the result of a long period of optimisation and testing. The working of the apparatus is demonstrated by the measurement of some samples.
7
Berrie, Jeffery A. "Measurement of electrical parameters for planar materials /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487759436328874.
Full text
8
Blad, Börje. "Electrical impedence tomography for temperature measurement in hyperthermia." Lund : Dept. of Electrical Measurements, Lund Institute of Technology, 1994. http://catalog.hathitrust.org/api/volumes/oclc/39225511.html.
Full text
9
Ricketts, David. "Diagnosis of occlusal caries by electrical resistance measurement." Thesis, King's College London (University of London), 1995. https://kclpure.kcl.ac.uk/portal/en/theses/diagnosis-of-occlusal-caries-by-electrical-resistance-measurement(1bbd1235-84ef-427f-ae04-65591cc71d66).html.
Full text
10
Jones, Paul. "Electrical measurement of large area substation earth grids." Thesis, Swansea University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367883.
Full text
11
Ritchie, L. J. "Detection, measurement and analysis of electrical insulation oils." Thesis, Cranfield University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273956.
Full text
12
Tronko, V. D., M. O. Chuzha, В. Д. Тронько, and М. О. Чужа. "Measuring current in electrical circuits using a polarimeter." Thesis, National aviation university, 2021. https://er.nau.edu.ua/handle/NAU/50502.
Full textAbstract:
In the presented work, an optical device for measuring current is proposed. It consists of a polarimeter, indicator and input device. Its work is based on the functional dependence of changes in the parameters of polarized light in the polarimeter from the current values that are being measured. The proposed current meter allows to reduce the dimensions and weight of the structure, as well as to increase the measurement accuracy.В представленій роботі запропоновано оптичний пристрій для вимірювання струму. Він складається з поляриметра, індикатора та вхідного пристрою. В основу його роботи покладено функціональна залежність зміни параметрів поляризованого світла в поляриметрі від значень струму, що вимірюються. Запропонований вимірювач струму дає можливість зменшити габарити та масу конструкції, а також підвищити точність вимірювань.
13
Bowlan, Pamela. "Measuring the spatiotemporal electric." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28188.
Full textAbstract:
Thesis (M. S.)--Physics, Georgia Institute of Technology, 2009.Committee Chair: Rick Trebino; Committee Member: Jennifer Curtis; Committee Member: John Buck; Committee Member: Mike Chapman; Committee Member: Stephen Ralph.
14
Tekgun, Burak. "Analysis, Measurement and Estimation of the Core Losses in Electrical Machines." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1481047992739036.
Full text
15
Sun, Wei Ping. "Measurement and analysis of MnS precipitation in electrical steels." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39266.
Full textAbstract:
A newly developed creep method is described for following the kinetics of manganese sulfide precipitation in four electrical steels. The technique was also applied to a Ti steel, in which the precipitation kinetics were previously determined using a stress relaxation method. The resulting creep rate is sensitive to the occurrence of precipitation; thus the slope of the true strain-log(time) curve decreases immediately after the initiation and increases on the completion of precipitation. The precipitation-time-temperature diagrams determined in this way are of classical C shape on all of the tested materials. Because higher dislocation densities and internal stress levels are maintained, the present technique is more effective for monitoring the precipitation events occurring in the ferritic phases and at high temperatures than the previously developed stress relaxation method.The nucleation sites for precipitation during creep testing were investigated with the aid of electron microscopy. It was concluded that the progress of MnS precipitation can be divided into three stages: nucleation, growth and coarsening. There exists a strong tendency for the nuclei to be formed on dislocations at lower temperatures. However, nucleation at grain boundaries is preferred as the temperature is increased. The classical diffusion-controlled growth theory is not satisfactory for strain-induced MrS precipitation. Thus, a modification was made in such a dynamic case by taking the effects of deformation vacancies into account. The kinetics during the coarsening stage are controlled by both bulk and grain boundary diffusion.
The microstructural examinations revealed that both grain deformation and grain boundary sliding take place in the electrical steels at hot working temperatures. Quantitative evaluations showed that the latter process contributes about one-sixth to one-tenth the total strain under the current experimental conditions. The strong retardation of grain deformation after the occurrence of precipitation is explained in terms of the interfacial pinning of mobile dislocations by these incoherent particles. It is also demonstrated that the finely-dispersed precipitates slow down the boundary sliding rate. (Abstract shortened by UMI.)
16
A'Arabi, M. M. "Novel methods for measuring power loss in electrical steels." Thesis, Bucks New University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380858.
Full text
17
Kolic, Edo. "Bearing current and shaft voltage measurement in electrical motors." Thesis, Högskolan Väst, Avdelningen för data-, elektro- och lantmäteriteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-10722.
Full textAbstract:
Due to the fast-rising voltage pulses of pulse width modulated drives, the generated shaft voltage of electrical motors causes electrical discharge currents in bearings. These discharges can cause bearing failure leading to costly maintenance and unexpected production stops. To eliminate the raised shaft voltage, several techniques are used such as shaft grounding brushes, insulated bearings and conductive grease. The possibility to measure discharge activity on a PWM driven induction motor offers a tool for researchers to test different bearings in electric motors. In order to measure the shaft voltages and bearing currents, modifications of an induction motor are made firstly using 3D software and then on the physical motor. By insulating the bearing from the frame and attaching a copper ring to the bearings outer race bearing currents can be measured. The combined measurements of shaft voltage, bearing currents and frame currents shows the bearings conductive states at low speed, and insulated state at higher speed. Electrical discharge activity (DA) is observed as shaft voltage raises, resulting in a bearing current spike and shaft voltage drops rapidly while stator current is unaffected. Experimental tests were performed with a sample bearing at different operating conditions, such as operating speed, temperature, motor load, etc., to determine the effect of the common mode voltages on bearing currents and shaft voltages. At low temperatures between 23-26 ˚C and motor speeds above 1000 rpm EDM currents were observed. On temperatures above 40 ˚C no major EDM currents were observed regardless of rpm due to the bearing remaining in an ohmic conductive state. The modifications of the motor have shown to give reliable bearing current and shaft voltage measurements that can help in future research in this area.
18
Henriksson, David, and Oscar Johansson. "Energy Measurement of Electric Fence." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-80547.
Full textAbstract:
Syftet med denna rapport är att få en inblick hur elstängselaggregat fungerar och hur energimängden, från en stöt, noterar. Det har då tagits fram en förstudie om vilka elstängselaggregat och vilka mätinstrument som ska användas. Mätningar har gjorts både i laborationsmiljö och ute i jordbruksmiljö. En enklare funktion och uppbyggnad har undersökts och kontrollerats för att visa strömmar och spänningar från varje elstängselaggregat. Energimängden kan sedan räknas ut. Dessutom tar rapporten upp problem i jordbruksmiljö och i instrumenten.
19
Zhao, Dong. "Exploring Construction Safety and Control Measures through Electrical Fatalities." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/71712.
Full textAbstract:
Globally, construction is considered a hazardous industry with a disproportionate amount of fatal and non-fatal injuries as compared to other industries. Electrocution is named as one of the "fatal four" causes for construction injuries by the Occupational Safety and Health Administration (OSHA). In the United States, an average of 47.9% electrical fatalities occurred in the construction industry from 2003 to 2012, according to the U.S. Department of Labor. These fatalities include both electrical workers and non-electrical workers. Such a disproportionate rate suggests a need of research to improve construction safety and reduce injuries due to electrocution. However, there is a lack of understanding of causation mechanisms surrounding fatal accidents by electrocution using a systems approach; and there is a disconnection between the mechanism of fatal electrocution accidents and the associated control measures, which may lead to less effective prevention in construction.
This dissertation has three objectives, including: (a) establishing a sociotechnical system model that reflects the electrocution occurrence in the U.S. construction industry and identify the associations among its internal subsystems; (b) determining specific electrocution patterns and associated mechanism constraints; and (c) examining hierarchy of control (HOC) measures and determining their appropriateness.
Findings from his research include: (a) the identification of three system patterns of electrocution in construction work systems and the associations between personnel, technological, organizational/managerial subsystems, and the internal and external environment for each of the three patterns, using a macroergonomics framework; (b) the identification of five features of work, and map out their decision-making chains, critical decision-making points and constraints, as an interpretation of electrocution mechanisms in the workplace; and (c) revealing that behavioral controls remain prevalent in electrical hazard mitigation even though the knowledge of construction safety and health has increased in the past decades, and that the effectiveness of controls is not statistically different by construction type nor occupation.
Based on these findings, the research also suggests corresponding mitigation recommendations that construction managers shall strictly follow HOC rules by giving priority to higher level of controls and upgrading the industry's prevention strategy by introducing more technological innovations and encouraging prevention through design (PtD) strategies.Ph. D.
20
Weemees, Ilmar Andrew. "Development of an electrical resistivity cone for groundwater contamination studies." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28730.
Full textAbstract:
The evaluation of groundwater quality has become increasingly important as more industrial waste and solid domestic refuse comes into contact with groundwater. Often the quantity and extent of contamination is determined by direct sampling of the groundwater and soil. An alternative method of detecting contaminated groundwater is by noting the electrical resistivity of the contaminated soil. The feasibility of logging resistivity while conducting cone penetrometer testing has been investigated in this research. To this end a two stage program was devised, consisting of lab testing and then field tests of a working tool.
Lab testing was carried out using a prototype probe designed to evaluate the feasibility of the project. The lab testing consisted of determining the resistivity of a number of different soil, electrolyte, and organic contaminant mixtures while varying the configuration of the probe. On the basis of lab testing the necessary requirements for the module dimensions and electronics were chosen and were fine tuned by field tests. The module itself consists of an insulated four electrode array and is mounted behind a standard 15 sq cm piezo-cone (CPTU). Upon completion of the development phase the instrument was tested at four different sites. From field testing it was determined that the resistivity cone (RCPTU) was able to accurately map changes in groundwater chemistry on the basis of resistivity measurements. The results of the resistivity testing were verified by groundwater sampling. It was also found that changes in lithological properties, as determined by the cone penetration test (CPT), could influence the resistivity. Basic guidelines for the use of the RCPTU in contaminant investigations are presented.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
21
Lai, Sin-yi, and 賴善怡. "Effects of low current electrical stimulation of neck muscles on voicing." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B46339188.
Full text
22
Boykov, Nikolay D. "Measurements of the electrical properties of coal measure rocks." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4715.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xi, 89 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 88-89).
23
PAU, MARCO. "State estimation in electrical distribution systems." Doctoral thesis, Università degli Studi di Cagliari, 2015. http://hdl.handle.net/11584/266606.
Full textAbstract:
The changes occurring in electrical systems, due to technical and economic reasons, and the requirements of a reliable and efficient delivery of the power supply to the customers demand a smarter management of the current grids at all the levels. In particular, the distribution level, until now managed without a detailed monitoring of its operating conditions, requires significant reinforcements, in terms of both measurement infrastructure and control functionalities, to deal with the changes in a t. In this context, Distribution System State Estimation tools play a key role, sin e they allow the estimation of the operating conditions of the distribution grid, representing the essential link between the measurements gathered from the field and the control functions envisaged in future Distribution Management Systems. In this thesis, the focus has been on the development of appropriate procedures to accurately perform DSSE. Several goals have been pursued. First of all, a DSSE algorithm specifically on conceived for the distribution systems and tailored to the features of these networks has been designed. The proposed estimator allows the proper processing of all the types of measurement, in luding both conventional measurements and new generation synchrophasors provided by Phasor Measurement Units. Particular attention has been paid to the measurement model to be used within the DSSE algorithm, since its implementation an strongly a e t the a ura y a hiev- able in the estimation results. Moreover, a simple method to handle the equality constraints, well suited to the proposed estimator, has been presented to improve its computational efficency. The proposed estimator has been riti ally analyzed and compared to other approaches available in the literature, in order to highlight strengths and weaknesses of the on eived solution. In the second part of the thesis, the problem of DSSE has been analyzed from a wider perspective, aiming at highlighting the impact of different measurement as- pe ts on the estimation results. The impact of measurement type and placement on the estimation a ura y of the different electrical quantities has been deeply investigated, supporting the empiric cal results through a detailed mathematical analysis. Such study an provide important guidelines for the choice of the measurement infrastructure to be deployed in future distribution systems in order to a achieve spe i a ura y targets for the estimation of the different electrical quantities. The possibility to enhan e the estimation a ura y by properly considering the measurement correlations has also been investigated. Developed analysis shows that different sources of correlation an exist in the measurements used as input to the DSSE algorithm. Performed simulations prove that the in lusion of these orrelations in the DSSE model an lead to significant benefits on the estimation a ura y. Finally, a possible de entralized multi-area ar hite ture, designed to handle large distribution networks, has been proposed. Su h a solution has been on eived duly taking into a ount the opposite requirements of a ura y, computational e ien y and low communication costs desirable in realistic scenarios. Even in this case, particular attention has been fo used on the proper modeling of the measurements in order to a hieve estimation results as a urate as possible. To this purpose, a mathematical analysis has been developed to assess the correlations arising in the proposed multi-area approach. Test results on rm the validity of the developed analysis and, above all, prove the importance of a proper consideration of all the measurement aspects for enhacing the a ura y of the estimations. In conclusion, in this thesis, the problem of state estimation in future distribution system has been deeply analyzed, focusing in particular on the issues related to the measurement modeling and processing. The analysis and the results presented in this thesis shows how the achievement of a really smart management and control of future distribution grids (as expected in the Smart Grid scenario) is strictly dependent on the smart deployment, processing and management of the measurements in the network.
24
Usdosen, Ndifreke. "Algorithms for selecting optimal measurement locations in electrical resistivity tomography." Thesis, University of Reading, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603521.
Full textAbstract:
The problem of determining optimal measurement setups that improve the resolution of reconstructed images is well known in several inverse problem applications such as magnetic tomography, electrical impedance tomography, and electrical resistivity tomography. In electrical resistivity tomography, for example, several optimisation strategies have been proposed, their aim being to collect "optimal datasets", which when inverted , should give tomographic resolutions close to that obtained from “comprehensive datasets" comprising all possible linearly independent measurements. While these optimisation strategies are useful, there has been no conceptual framework developed for finding optimal measurement setups within the context of inverse problems. Electrical resistivity tomography is an ill-posed inverse problem, and components of the inversion process influence the nature of reconstructions obtained. Such a framework would incorporate within its optimisation process important components of the inversion process. This research describes the development of sl1ch a meta inverse framework. The framework incorporates within its optimisation process important ingredients of an inversion process such as choice of regularisation parameter, nature and size of data error, and a priori knowledge on solutions. As a first example, 'the framework is implemented for an acoustic source reconstruction linear problem, the aim being to find optimal acoustic receiver locations at which best reconstructions of the acoustic source strength can be obtained. To improve the quality of acoustic source strength reconstructions, a framework adaption algorithm is developed for use with the meta inverse framework The adaption algorithm uses successive measurements to improve the quality of reconstructions. Numerical results from implementing the meta inverse framework illustrate its success at finding optimal locations at which best reconstructions of the acoustic source strength can be obtained. The results also show that the framework adaption algorithm can be successfully implemented to improve the quality of reconstructions. To implement the meta inverse framework for electrical resistivity tomography, new forward and inverse solvers were developed. The forward solver is based on the finite integration technique (FIT), the inverse solver is called the domain search algorithm. The FIT solver generates the 'simulated data for an assumed resistivity model of the subsurface; the domain search inverse solver searches to find a resistivity model that gives an acceptable fit to the simulated data. Numerical results from implementing these solvers show that they are successful in simulating and reconstructing the resistivity distribution in electrical resistivity tomography. To find optimal electrode locations from which best reconstructions can be obtained for a 2D 'resistivity tomography problem, the meta inverse framework is incorporated into the forward and inverse solvers. Numerical results from implementing these algorithms show that the meta inverse framework is successful in finding optimal electrode locations at which best reconstructions can be obtained.
25
Westerlund, Per. "Condition measuring and lifetime modelling of electrical power transmission equipment." Licentiate thesis, KTH, Elektroteknisk teori och konstruktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-167136.
Full textAbstract:
The electric grid is important in modern society, so the outages should be few. The transmission grid should have a real high availability, since it transports electrical energy across the country. Then, it is difficult to plan outages for maintenance and installation. This thesis lists twenty surveys about failures of circuit breakers and disconnectors, with data about the cause and the lifetime. It also contains a survey of about forty condition-measuring methods for circuit breakers and disconnectors, mostly applicable to the electric contacts and the mechanical parts. As there is no published method to monitor the electric contacts at voltages around 400 kV, a system with IR sensors has been installed at the nine contacts of six disconnectors. The purpose is to avoid outages for maintenance by estimating the condition of the contacts while the disconnectors are still connected to high voltage. The measured temperatures are collected by radio and regressed against the square of the current, since the best exponent for the current was found to be 2.0. The coefficient of determination $R^2$ is high, greater than 0.9. This gives for each contact a regression coefficient, which can serve as an estimate of the condition of the contact. The higher the coefficient is, the more heat is produced at the contact, which can damage the material. This enables a ranking of the different contacts and shows which the worst ones are. This coefficient can also give a dynamic rating of the disconnector.Elnätet är viktigt i det moderna samhället, så antalet avbrott bör vara lågt. Särskilt stamnätet bör ha en särskilt hög tillgänglighet, då det transporterar elektrisk energi tvärsöver landet. Då blir det svårt att planera avbrott för underhåll och utbyggnad. Denna avhandling tar upp tjugo studier av fel i brytare och frånskiljare med data om felorsak och livslängd. Den har också en översikt av ett fyrtiotal olika metoder för tillståndsmätningar för brytare och frånskiljare, som huvudsakligen rör de elektriska kontakterna och de mekaniska delarna. Eftersom det inte finns någon beskriven metod för att övervaka elektriska kontakter för spänningar på runt 400 kV, har ett system med IR sensorer installerats på de nio kontakterna på sex frånskiljare. Målet är att minska antalet avbrott för underhåll genom att skatta skicket hos kontakterna, när frånskiljarna fortfarande är kopplade till högspänning. De uppmätta temperaturerna tas emot genom radio och behandlas genom regression mot kvadraten av strömmen, då den bästa exponenten för strömmen visade sig vara 2,0. Förklaringsfaktorn $R^2$ är hög, över 0,9. För varje kontakt ger det en regressionskoefficient, som blir en skattning av kontaktens skick. Ju högre koefficienten är, desto mer värme utvecklas det i kontakten, vilket kan leda till skador på materialet. Kontakternas olika koefficienter ger en rankordning dem och därmed en möjlighet att prioritera vilken frånskiljare som ska underhållas först. Systemet kan också användas för att minska eller öka den tillåtna strömmen baserat på skicket.
QC 20150522
26
Lindström, Jonas. "Measurement system for laboratory use : For studies in electrical science." Thesis, Uppsala universitet, Elektricitetslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256667.
Full textAbstract:
The purpose of this project is to create a measurement system aimed for a laboratory environment at Uppsala University. The measurement system will be used by students for laboratories of electrical science. It will include a measurement station and an application that will be used by the students. A specification of 16 channels of measuring data, 8 current and 8 voltage, was given by the client. Beside this specification there were 8 others to fulfil. The measurement station is connected to a compactRIO which will enable the possibility to graphically and numerically represent the results through an application created in Labview. The application will include time and phasor representations of both current and voltage. It will also include two power vectors for 6 channels each. The result of this project is a fully working measurement system which generates a good overview of measurements made on an electrical power system. All given specifications was fulfilled except one, which was not possible to achieve with the chosen methodology.
27
Bennett, Mark Andrew. "On-line measurement of multiphase processes using electrical capacitance tomography." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302541.
Full text
28
Smith, George St J. V. "The characterisation of InSb quantum well heterostructures by electrical measurement." Thesis, Cardiff University, 2019. http://orca.cf.ac.uk/119553/.
Full textAbstract:
This thesis describes both experimental and theoretical work on the electronic transport properties of 30 nm InSb/AlInSb quantum well 2DEG heterostructures. Advances in the epitaxial growth of large lattice constant III-V materials using mismatched substrates like GaAs or Si has generated renewed interest in developing high mobility devices. Similarly, narrow gap semiconductors are promising candidates for the advancement of spintronic devices taking advantage of their extreme material parameters, such as the small effective mass and large effective Landé g-factor. An investigation of the low temperature Hall effect and Shubnikov-de Haas oscillations of asymmetrically doped InSb quantum well heterostructures has been made to determine the scattering mechanisms present for carriers in the 2D system. Modelling these oscillations by calculation of the density of states at the Fermi energy as a function of magnetic field was performed to analyse the effects of parameter variation on the observed oscillation. Application of a dielectric layer and gate electrode to the material surface has allowed for a carrier density dependent investigation of the transport properties to be performed. These investigations have provided a detailed understanding of the transport limiting scattering mechanisms over a range of carrier densities and temperatures. A novel study of the current-voltage characteristics of high resistance contacts has been performed to investigate the energetic distribution of electron states in the quantum well under the application of large magnetic fields. Clear Landau level quantisation of the 2D density of states for the first subband of the quantum well has been observed. Analysis of the high field asymmetry of the fundamental Landau level has revealed the presence of significant spin dependent broadening within the heterostructure, which has previously been suggested to exist from an asymmetry of the Fourier transform of Shubnikov-de Haas oscillation.
29
Philip-Chandry, Rekha. "Fluid flow measurement using electrical and optical fibre strain gauges." Thesis, Liverpool John Moores University, 1997. http://researchonline.ljmu.ac.uk/5565/.
Full textAbstract:
The design, development and calibration of three flow sensors to measure the speed and direction of fluid flow is presented in this thesis. The force exerted by the fluid flow on the sensors are measured using strain gauges. Multidirectional fluid flow measurement has been made possible by vectorial addition of the orthogonal flow components. The fluid speed and direction are generated irrespective of each other. Electrical resistance strain gauges are used as the force measuring device for the first version of the flow meter. These strain gauges are bonded to the four longitudinal surfaces of a square-sectioned, elastic, rubber cantilever having a drag element attached to its free end. An attempt has been made to optimise the shape and dimensions of the elastic beam to obtain a constant drag co-efficient over a wide flow range. Calibration of the electrical strain gauge flow sensor has been performed in a wind tunnel to measure air flow. The sensor has a repeatability of 0.02%, linearity within 2% and a resolution of 0.43 m/s. The most noteworthy feature of the flow sensor is its quick response time of 50 milliseconds. The sensor is able to generate a measurement of flow direction in two dimensions with a resolution of 3.6". Preliminary measurements in a water tank enabled the speed of water to be measured with a resolution of 0.02 m/s over a range from 0 to 0.4 m/s. An optical fibre strain sensor has been designed and developed by inserting grooves into a multimode plastic optical fibre. As the fibre bends, the variation in the angle of the grooves causes an intensity modulation of the light transmitted through the fibre. A mathematical model has been developed which has been experimentally verified in the laboratory. The electrical strain gauge was replaced by the fibre optic strain gauge in the second version of the flow sensor. Two dimensional flow measurement was made possible by attaching two such optical fibre strain gauges on the adjacent sides of the square sectioned rubber beam. The optical fibre flow sensor was successfully calibrated in a wind tunnel to generate both the magnitude and direction of the velocity of air. The flow sensor had a repeatability of 0.3% and measured the wind velocity up to 30 M/s with a magnitude resolution of 1.3 m/s and a direction resolution of 5.9'. The third version of the flow sensor has used the grooved optical fibre strain sensor by itself without the rubber beam to measure the fluid flow. Wind tunnel calibration has been performed to measure two dimensional wind flow up to 35 m/s with a resolution of 0.96 m/s.
30
Yaremyk, R. Ya. "DSP-Based Information-Measuring Microdevice for Electrical Impedance Spectroscopy Analysis." Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/47278.
Full text
31
Faraj, Yousef. "Measurement and visualisation of slurry flow using electrical resistance tomography." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/4604/.
Full textAbstract:
Slurry transport has been a progressive technology for transporting a huge amount of solid materials across the world in both, long distance and short commodity pipelines. The occurrence of separation and slippage of the constituent phases within the pipeline make these flows unpredictable and time dependent. Therefore, it is paramount for the operator of slurry pipelines to monitor and measure the flow continuously, particularly from the local point of view. Undoubtedly, the measurement of local parameters governing the flow, requires an instrument that provides high temporal resolution. Besides, since each phase has different behaviour and flow characteristics within the pipe, it is enormously difficult to measure the flow parameters of each phase using only one conventional flow meter. Thus, a second auxiliary sensor is required to develop a compact and multiphase flow meter. This project proposes a new automated online slurry measurement, visualisation and characterization technique, in which a high performance dual-plane Electrical Resistance Tomography (ERT) system is employed with a capability of acquiring data at a rate of 1000 dual-frames per second. It also proposes an ERT based technique, which combines the ERT and an Electromagnetic Flow meter (EMF), to measure volumetric flow rate of each phase, and thus the total slurry volumetric flow rate. The ERT is further combined with the cross-correlation technique to estimate and image the axial solid’s velocity distribution, through which the transient phenomena of horizontal flow regimes can be visualised. The ERT is used for estimation of several parameters of stratified flow. The development of a novel automated technique for recognition of horizontal slurry flow regimes is also described. A series of experiments were carried out on horizontal and upward vertical sand-water flow through a pilot scale flow system with 50 mm ID pipeline. Two sands, medium and coarse, were employed in two throughput concentrations (2% and 10%) within the range of transport velocities 1.2-5.0 m/s. The solids volumetric concentration and velocity, along with slurry volumetric flow rate are compared with the corresponding results obtained from a sampling vessel.
32
Starrs, Gerard. "Measurement of the electrical properties of concrete at radio frequencies." Thesis, Edinburgh Napier University, 1994. http://researchrepository.napier.ac.uk/Output/6573.
Full textAbstract:
This thesis is a presentation of research into the elecrical properties of concrete at radio frequencies (1-1000 MHz). The physical properties of concrete are examined and found to be profoundly influenced by water both at gauging and at later stages of development. The merits of currently used test methods for quality assessment of concrete are discussed. The theory of polarization in dielectric materials is examined and a range of formulae suitable for frequency dispersion calculations in homogeneous and heterogeneous materials is presented. A review of previous research into the electrical properties of concrete at frequencies in and below the RF range, including a brief description of Ground Probe Radar techniques, is presented and the results discussed. A distinct shortage of data is found in the 100-1000 MHz range. The electrochemical properties of concrete are considered and their influence on the electrical properties is examined. A previous hypothesis in this area, based on the behaviour of ions in the mix water, is shown to be incorrect, but a new hypothesis relating the dielectric dispersion of fresh concrete to ionic effects at the surface of hydrating cement grains is proposed. The results from calculations based on the hypothesis are compared with available data at 1-1000 MHz and found to be in agreement. A geophysical explanation, previously derived for sedimentary rocks, is proposed as an influencing factor on the electrical properties of hardening concrete in the same frequency range. Measurement techniques at radio frequencies are considered and the application of these to concrete measurements is discussed with reference to two particular electrode systems at 1-100 MHz and 100-1000 MHz. A technique for calibrating out the effects of connector distortion is described and the results of tests presented. The results from a range of experiments on various concrete mixes in the 1-1000 MHz range are presented and discussed. The data obtained for fresh concrete agree very well with the hypothesis. The data for hardening concrete show a qualitative agreement with the relevant hypothesis. The probable effects on Ground Probe Radar signals of the dispersion observed for hardening concrete in the 100-1000 MHz range are discussed. Suggestions for further research are given.
33
Fulton, William Sean. "Electrical impedance tomography applied to body-support interface pressure measurement." Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336236.
Full text
34
Siebrits, F. B. (Francois Bart). "Field implementation of a transient voltage measurement facility using HV current transformers." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53426.
Full textAbstract:
Thesis (MScEng)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: The bandwidth of standard HV measurement devices such as capacitive voltage transformers is too limited in order to measure wideband phenomena. This thesis is concerned with the investigation into a non- intrusive HV transient voltage measurement facility using standard substation HV current transformers (CI's) configured in a transconductance topology. The sensing, summation and integration of the CT capacitive earth currents are investigated. This thesis also reports on the development of a optically isolated link using optical fibre for signal transfer and a computer based data acquisition system.
AFRIKAANSE OPSOMMING: Standaard hoogspannings (HS) meettoerusting soos kapasitiewe spannmgs transformators het beperkte bandwydte vir die meet van wyeband verskynsels. Hierdie tesis handel oor die implementering van 'n HS meetstelsel wat op meinbrekende wyse oorgangsverskynsels meet deur middel van HS stroomtransformators wat in 'n transkonduktansie topologie gekonfigureer is. Die meet, sommasie en integrasie van kapasitoewe grondstrome word ondersoek. Hierdie tesis doen ook verslag aangaande die ontwikkeling van 'n optiese geisoleerde koppelvlak wat gebruik word vir seinoordrag en 'n rekenaar gebasseerde data versamelaar.
pdv201406
35
Groenewald, Ben. "Substrate curvature measurement system." Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/19376.
Full textAbstract:
Industry often requires, in a variety of processes, the measurement of deformation induced in a solid object by mechanical stress. One such process is during the manufacture of very large scale integrated circuits (VLSI). During this process a substrate is coated with a thin film to protect the micro circuitry formed on the substrate. Due to the differences in thermal expansions between film and substrate, mechanical stresses can develop which may lead to deformation of the substrate surface. Any deformation of the substrate surface will result in mechanical stress in the interconnections of the circuitry, which could result in severe damage to the operation of the circuit. Different measurement techniques are available to measure the spherical deformation of substrates, with the latest known technique being a combination of a laser beam deflection and light scattering techniques. Many of the existing techniques reveal shortcomings, one of which is a 2-dimensional scanning capability with a minimum of moving components. Another shortcoming is the incapability of previous techniques to calculate the relative error which the measuring technique induces into the results. The aim of this study has been to develop an electro-optical system embodying the successful principles of these techniques in a system which will eliminate the shortcomings and produce results in excess of those previously recorded. In this work, we have concentrated on discussing the development of a system which will produce in situ real time monitoring of mechanical stresses in a solid. The system includes the minimization of system induced errors through the calculation of error voltage gains, and the introduction of a 2-dimensional scanning capability to determine the true position of the laser beam without prior knowledge of the initial substrate curvature. A four-quadrant position sensitive detector (PSD) with relevant Lab View software and programs were also introduced into the system.
36
AGUIAR, ALEXANDRE STREET DE. "CERTAINTY EQUIVALENT AND RISK MEASURES IN ELECTRICAL ENERGY TRADE DECISIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11477@1.
Full textAbstract:
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOEm problemas de decisão sob incerteza que dependam da preferência entre fluxos multi-período, como é o caso dos problemas de comercialização de contratos de energia elétrica no Brasil, o agente deve saber expressar sua preferência por diferentes distribuições em cada período e, além disso, deve também especificar uma preferência entre períodos. Classicamente a abordagem utilizada é definir um funcional de preferência de von Neumann e Morgenstern separável entre os períodos, composto pela soma da esperança de utilidades que modelam a preferência em cada período. Então, para expressar a preferência entre períodos, esta soma é ponderada por um fator de desconto que visa expressar a impaciência do agente no consumo entre os períodos. Nesta abordagem, a especificação do fator de desconto torna-se uma tarefa bastante subjetiva, uma vez que estamos ponderando utilidades esperadas e não valores monetários. Devido a essa subjetividade e da dificuldade de se especificar a própria função utilidade de cada período, os grupos de finanças divergiram para uma abordagem mais pragmática, baseada na análise e controle dos riscos assumidos em suas decisões. Neste sentido, a empresa que busca maximizar a expectativa de lucro, especifica em valores monetários, um conjunto de restrições sobre as perdas que esta está disposta a incorrer, baseando-se para isso em suas probabilidades de ocorrência. Assim, durante as ultimas quatro décadas, muitas pesquisas e desenvolvimentos foram realizados nesta área, no sentido de se estabelecer medidas de risco que proporcionassem propriedades desejáveis para essa classe de problemas. Desta forma, criou-se um gap entre as duas abordagens, financeira e econômica, as quais possuem raízes em comum: modelar o comportamento de agentes frente ao risco. Assim sendo, esta tese tem três objetivos: (i) propor uma abordagem alternativa para o uso de funções utilidades em problemas de comercialização de energia elétrica multi-período, baseada no valor presente dos equivalentes certos de cada período; (ii) mostrar como tal abordagem pode ser modelada matematicamente e formulada através de um problema de programação linear inteira mista (PLIM) ao considerarmos uma função utilidade linear por partes, e (iii) mostrar a conexão entre a teoria de utilidade e problemas de maximização da renda esperada sujeito a restrições de risco do tipo alfa-CVaR.
In decision under uncertainty problems that depend on multi- period preferences, as the case of trading electricity contracts in Brazil, agents should expresses their inter and intratemporal preferences. The classical economical approach is to define a time separable von Neumann and Morgenstern utility functional. This functional is composed by the sum of the expected utility of each period times an impatience factor that should express the agent`s intertemporal preference. This approach demands the specification of a subjective impatience factor, which should weight utilities units. Due to this subjectiveness and its estimation difficulties, the applied financial groups started to develop more pragmatic approaches based on risk control. In this sense, companies that maximize expected profit will impose constraints on acceptable losses using estimated occurrence probabilities of different outcomes. In this sense, the economical and applied financial approaches have been diverging in the last four decades and, during this time, many studies and developments have been done in the risk metrics field to generate and prove stability and coherence properties for the proposed metrics. This thesis has three main objectives: (i) propose an alternative approach for multi-period decisions problems based on the present value of the certainty equivalent of each period; (ii) show how this approach can be modeled as a mixed integer linear programming problem (MILP) when adopting a piecewise linear utility function; and (iii) provide connections between utility theory and expected maximization problems constrained to alpha-CVaR risk metrics.
37
Haddad, Stephen. "Texture measures for segmentation." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/7461.
Full textAbstract:
Includes bibliographical references (p. 67-72).Texture is an important visual cue in both human and computer vision. Segmenting images into regions of constant texture is used in many applications. This work surveys a wide range of texture descriptors and segmentation methods to determine the state of the art in texture segmentation. Two types of texture descriptors are investigated: filter bank based methods and local descriptors. Filter banks deconstruct an image into several bands, each of which emphasises areas of the image with different properties. Textons are an adaptive histogram method which describes the distribution of typical feature vectors. Local descriptors calculate features from smaller neighbourhoods than filter banks. Some local descriptors calculate a scale for their local neighbourhood to achieve scale invariance. Both local and global segmentation methods are investigated. Local segmentation methods consider each pixel in isolation. Global segmentation methods penalise jagged borders or fragmented regions in the segmentation. Pixel labelling and border detection methods are investigated. Methods for measuring the accuracy of segmentation are discussed. Two data sets are used to test the texture segmentation algorithms. The Brodatz Album mosaics are composed of grayscale texture images from the Brodatz Album. The Berkeley Natural Images data set has 300 colour images of natural scenes. The tests show that, of the descriptors tested, filter bank based textons are the best texture descriptors for grayscale images. Local image patch textons are best for colour images. Graph cut segmentation is best for pixel labelling problems and edge detection with regular borders. Non-maxima suppression is best for edge detection with irregular borders. Factors affecting the performance of the algorithms are investigated.
38
Xiao, Lianzhen. "Interpretation of hydration process of concrete based on electrical resistivity measurement /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20XIAO.
Full text
39
Pérez-Vázquez, Losada Sonia. "Implementation of and Electrical Bioimpedance Measurement System for Renal Function Monitoring." Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-18839.
Full textAbstract:
Peritoneal Dialysis is a treatment for patients suffering from renal failure thatallows out-patient care. This means that the patient only needs to visit the hospital forconsultation and not for treatment, increasing considerably the comfort of the patient,while reducing remarkably the cost per patient.In order to increase the level of medical supervision obtained with the periodicvisits to the clinic, televisit has been put into practice in some hospitals. But thesetelevisits are based on indirect and qualitative indicators of renal failure, and thereforethey are just valid for detection of situations near limit cases, such as well over-hydratedor dehydrated.Electrical Bioimpedance Measurements have been proved to constitute anappropriate method for assessment of body composition, and therefore they can providewith direct indicators of body fluid distribution. Such ability of EBI technology allowsthe detection of body fluid unbalance caused by renal dysfunction, and therefore,nephrology televisits would benefit tremendously from EBI measurements.This project is based on the AD5933 Impedance Network Analyzer of AnalogDevices, and the main task is to develop a software application that controls theevaluation board in which it is implemented, and allows the storage of the EBImeasurements in EDF+ files that will facilitate the management of medical data whenapplied to televisit. These files are uploaded to XML format in order to be sent to aremote server, where a software application will have been implemented for medicalconsultation.Uppsatsnivå: D
40
Amruthaluri, Sushma. "Synthesis of copper carbon nanotube composite and its electrical conductivity measurement." FIU Digital Commons, 2008. http://digitalcommons.fiu.edu/etd/1283.
Full textAbstract:
The matrices in which Multi Walled Carbon Nanotubes (MWCNTs) are incorporated to produce composites with improved electrical properties can be polymer, metal or metal oxide. Most composites containing CNTs are polymer based because of its flexibility in fabrication. Very few investigations have been focused on CNT-metal composites due to fabrication difficulties, such as achievement of homogeneous distribution of MWCNTs and poor interfacial bonding between MWCNTs and the metal matrix. In an effort to overcome poor interfacial bonding for the Cu - MWCNT composite, silver (Ag) and nickel (Ni) resinates have been incorporated in the ball milling stage. Composites of MWCNT (16, 12, and 8 Vol %) - Cu+Ag+Ni were pelleted at 20,000 psi (669.4 Mpa) and sintered at 950 °C. The electrical conductivity results measured by four probe meter showed that the conductivity decreases with increase in the porosity. Moreover from these results it can also be stated that an addition of optimum value of (12 Vol %) MWCNT leads to high electrical conductivity (9.26E+07 s-m"), which is 50% greater than the conductivity of Cu. It is anticipated that the conductivity can be increased substantially with hot isostatic pressing of the pellet.
41
Entus, Jonathan. "Use of time domain reflectometry to monitor water content and electrical conductivity of saline soil." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0032/MQ64350.pdf.
Full text
42
Johanssson, Stefan. "Precision Amplifier for Applications in Electrical Metrology." Thesis, Linköping University, Linköping University, Electronics System, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-16896.
Full textAbstract:
This master's thesis addresses two main problems. The first is how to suppress a common mode voltage that appears for current shunts, and the second how to let a voltage divider work under an unloaded condition to prevent loading errors and thereby a decreased measurement accuracy. Both these problems occurs during calibration of power meters, and verification of current shunts and voltage dividers. To the first problem three alternative solutions are presented; prototype a proposed instrumentation amplifier circuit, evaluate the commercial available instrumentation amplifier Analog Devices AD8130 or let the voltage measuring device suppress the common mode voltage. It is up to the researchers at SP to choose a solution. To address the second problem, a prototype buffer amplifier is built and verified. Measurements of the buffer amplifier show that it performs very well. At 100 kHz, the amplitude error is less than 20 μV/V, the phase error is less than 20 μrad, and the input Rp is over 10 MΩ. This is performance in line with the required to make accurate measurements possible at 100 kHz and over that.
43
Niemi, Jan. "Towards a new sensing strategy for measuring paper pulp properties : a combination of ultrasonic and optical measurement techniques." Licentiate thesis, Luleå : Luleå University of Technology, 2007. http://epubl.ltu.se/1402-1757/2007/17/.
Full text
44
Dupont, Anne-Caroline. "Therapeutic electrical stimulation, reversal of disuse atrophy and clinical outcome measures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ56077.pdf.
Full text
45
Ballard, Norman. "Electrode length measurement in electric arc furnaces." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/18232.
Full textAbstract:
Accurate measurement of electrode length in electric arc furnaces will result in decreased maintenance time, and improved plant productivity. This thesis describes the development of a microwave-based Soderberg electrode length-measurement system. Various methods of electrode-length measurement were investigated, and it was found that a microwave measurement system based on a conventional frequency modulated continuous wave (FMCW) radar presented the most feasible technique. In this system, microwaves are propagated down a waveguide placed in the electrode. As the waveguide melts, they continue propagating in the resulting cavity until they are reflected by the discontinuity at the bottom of the electrode. The time taken for the return journey to the bottom of the electrode and back is measured, and the electrode length calculated.
46
AHMAD, SHOAIB. "Finite Precision Error in FPGA Measurement." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-49646.
Full textAbstract:
Finite precision error in digital signal processing creates a threshold of quality of the processed signal. It is very important to agree on the outcome while paying in terms of power and performance. This project deals with the design and implementation of digital filters FIR and IIR, which is further utilized by a measurement system in order to correctly measure different parameters. Compared to analog filters, these digital filters have more precise and accurate results along with the flexibility of expected hardware and environmental changes. The error is exposed and the filters are implemented to meet the requirements of a measurement system using finite precision arithmetic and the results are also verified through MATLAB. Moreover with the help of simulations, a comparison between FIR and IIR digital filters have been presented.Passed
Digital filters and FPGA
47
Chuang, W. C., and 鍾旺成. "Electrical Characteristic Measurement of GaN." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/77249529553401108009.
Full textAbstract:
碩士國立交通大學
電子物理系
86
We has successfully grown the GaN film using metalorganic chemical phase deposition method. From the Van der Pauw and Hall measurement, it is found that the GaN film quality is very sensitive to the growth conditions, such as buffer layer thickness, ramping rate of buffer layer thermal annealing, growth temperature, growth rate, nitridation and V/Ⅲ ratio. Nevertheless, a device quality of GaN film has been obtained. The corresponding carrier mobility as high as 300 cm2/Vs and carrier concentration is lower than 1017 cm-3. Moreover, a schottky diode coated by Pd on n-type GaN was fabricated. The measured ideality factor is of 1.115 and the barrier heights as determined by I-V, I-V-T, C-V measurements are -0.9 eV, 0.91 eV and 1.23 eV, respectively. These values indicate a good quality of our GaN film. In addition, we have found that the GaN films prepared by our group possess a majority-carrier trap located at 0.435 eV below conduction band. Since the trap contration and cross-section are rather low (5.64×1014 cm-3 and 4.618×10-18 cm-2 respectively), we believe this trap will not bring any affections on the performance of GaN devices.
48
Yang, Kao-Yueh, and 楊國岳. "Electrical Modeling and Measurement for." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/83220013283298017260.
Full textAbstract:
碩士國立中正大學
電機工程研究所
89
This thesis establishes an RF circuit model for the plastic ball grid array (PBGA) package from the approach of time-domain and frequency-domain measurements. The test fixture, specially designed for the PBGA436 package, is developed to ensure the measurement accuracy and reliability. The time-domain measurement is performed with Time Domain Reflection Analyzer (TDR), from which the element values of the circuit model are extracted. To extend the applicable frequency range of the model, the frequency-domain S parameters are measured by Vector Network Analyzer (VNA). With these results, the circuit model established by the time-domain measurement is improved to the 5GHz range.
49
Lu, I.-Cheng, and 盧奕丞. "Fabrication and Electrical Measurement of MoS2 Transistors." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/3v83ep.
Full textAbstract:
碩士國立中興大學
物理學系所
101
We report the fabrication and the characterization of Molybdenum disulfide (MoS2) thin film transistors. During the fabrication process, we first exfoliated a nano-scale thin film MoS2 layer from a commercial MoS2 ore mechanically by using 3M scotch tapes and transferred it to a heavy doped Si substrate with a 300-nm SiO2 insulating layer. The thickness of the MoS2 layers was identified by the Raman spectroscopy with a 488-nm-wavelength laser and the atomic force microscope. Ti/Au electrodes were defined by e-beam lithography. The Si substrate is use as the back-gate. From the I-V characteristics of the device, the mobility μ = 0.2 cm2V-1s-1, on/off ratio>10000, threshold voltage Vth= 6.87 V, and transconductance gm = 0.013 μS for a device with channel width of 2.2μm, channel length of 0.8μm, and film thickness of 17.3nm. We also observed that the MoS2 transistor is also sensitive with light.
50
Chang, Lun-Wei, and 張倫瑋. "Electrical measurement of one-dimensional carbon nanotube." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/57998484359936320095.
Full text