Dissertations / Theses: 'Dielectric measurement'

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Chowdhry, Bhawani Shankar. "On-line measurement of dielectric relaxation." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277344.

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Coln, Michael Christian Wohnsen. "A high performance dielectric measurement system." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15251.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1985.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Includes bibliographical references.
by Michael Christian Wohnsen Coln.
Ph.D.

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Mercer, Sean R. "Online microwave measurement of complex dielectric constant." Doctoral thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/8342.

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Includes bibliographical references.
This dissertation examines the problem of on-line measurement of complex dielectric constant for the purpose of dielectric discrimination or product evaluation using microwave techniques. Various methods of signal/sample interaction were studied and consideration was given to the problem of sorting irregularly shaped discrete samples. The use of microwave transmission and reflection measurements was evaluated. The signal reflection methods were deemed to be best suited to applications with constant geometry feed presentation ( ie. a continuous, homogeneous product stream with little variation in surface geometry).

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Umaña, Juan Antonio. "Measurement of complex dielectric permittivity of pavement materials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0004/MQ32519.pdf.

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Stafford, Robert Bruce. "Time domain metrology for dielectric spectroscopy of particulates." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-171849/.

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Waldron, Isaac James. "Ring Resonator Method for Dielectric Permittivity Measurements of Foams." Digital WPI, 2006. https://digitalcommons.wpi.edu/etd-theses/666.

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Dielectric permittivity measurements provide important input to engineering and scientific disciplines due to the effects of permittivity on the interactions between electromagnetic energy and materials. A novel ring resonator design is presented for the measurement of permittivity of low dielectric constant foams. A review of dielectric material properties and currently available measurement methods is included. Measurements of expanded polystyrene are reported and compared with results from the literature; good agreement between measurements and published results is shown.

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Helgeson, Anders. "Analysis of dielectric response measurement methods and dielectric properties of resin-rich insulation during processing." Doctoral thesis, KTH, Electric Power Systems, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2972.

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The dielectric diagnostic methods ofpolarisation/depolarisation currents and recovery voltage,which are time domain methods, and capacitance and tandmeasurements at different frequencies, which is a frequencydomain method, have been studied here. In the first part of thethesis, these measurement methods are analysed and evaluated.Three different types of insulation systems are included in theevaluation, oil/paper ("high" loss), resin-rich mica tape("medium" loss) and cross-linked polyethylene, XLPE, ("low"loss). These three systems have different dielectric responsein both shape and magnitude. Conclusions are made regardingchoice of measurement method depending on the dielectricresponse of the insulation material. Examples are also given ofhow to estimate conductivity and the dielectric responsefunction in the time domain from measurements with a finitecharging period.

Furthermore, relations between time domain and frequencydomain and the possibilities of Fourier transforming data fromone domain to the other are discussed. Fourier transforming isdone with a spline approximation technique, the Hamonapproximation and by fitting base functions that have analyticFourier transforms to measured data. These techniques arereviewed with special attention to the problem of estimatingdata outside the measurement window.

The second part of the thesis includes studies of the changeof dielectric properties during the manufacturing stage of acomposite insulation used in high voltage rotating machines.The insulation consists of a resin-rich mica tape with wovenglass or polyester film (PET) as carrier material. The aim wasto improve the quality of the composite insulation byoptimising the heat and pressure cycle used in theproduction.

A test cell has been designed and built to be able toprocess simple parallel plate samples under conditions similarto the factory process. With a maximum heating rate of 9°C/min and a maximum cooling rate of 20° C/min arbitrarytemperature paths could be programmed. All samples wereprocessed under static pressure in the MPa range.

The chemical reaction during curing of the resin-rich micatape was studied with differential scanning calorimetry (DSC).A simple reaction rate model was fit to the DSC measurementsmaking it possible to calculate the degree of curing during anarbitrary temperature path.

The change of dielectric response with time during curingunder different temperature paths and at a constant pressurewas monitored. Both laboratory experiments and factorymeasurements have been made and based on these measurements asimple network model is proposed to explain the measureddielectric response in terms of material structure and degreeof curing.

Keywords: Dielectric response, diagnostic methods, Hamon,Fourier transform, rotating-machine, insulation, resin-rich,mica tape, curing, process, monitoring, differential scanningcalorimetry (DSC), network model.

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Rimbi, Morris. "Wood microwave dielectric heating and measurement of material properties." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50231.

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Thesis (PhD)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: Microwave heating technology is extensively used in households, is well-established in certain industries and is being explored in others. lts attraction is that it is quick, energy efficient, clean and can be used to heat materials of both high and low thermal conductivities. Successful application of the technology requires knowledge of both material properties and microwave equipment. Commercial fixtures for measuring dielectric properties are not widely available and are usually created in-house. The domestic oven magnetron is easily available and can be used in prototype microwave systems but applicators for specific applications need development. This thesis covers three main areas, namely; dielectric measurement fixtures, microwave applicators and chokes, and drying of wood. The first part of the thesis presents four dielectric measurement fixtures, one commercial and the others in-house. The design and calibration of the in-house fixtures is presented. An intercomparison of the performance of the four fixtures is carried out by measuring the permittivities of well characterised dielectrics: teflon and perspex. The most convenient fixture is used to measure the dielectric properties of wood at different moisture contents. The second part covers the design of a slotted waveguide fed microwave applicator and a choke. The design of the slotted feed is carried out analytically with and without mutual coupling between the slots. A semi-empirical design using a finite element package is done independent of the analytical approach and the results are compared. The choke is rigorously characterised using a procedure which avoids de-embedding. The third and last section reports on the wood drying experiments carried out in the applicator, simulated and mapped heating patterns of drying wood, and a mock-up industrial wood drying facility.
AFRIKAANSE OPSOMMING: Mikrogolfverhittingstegnologie word wyd gebruik in huishoudings, is goed gevestig in sekere nywerhede en moontlike gebruike daarvan op ander gebiede word gedurig ondersoek. Die vernaamste voordele is dat dit vinnig, energiedoeltreffend en skoon is en dat dit gebruik kan word om materiale van beide hoë en lae termiese geleidingsvermoë te verhit. Suksesvolle toevoeging van die tegnologie vereis kennis van beide materiale-eienskappe en mikrogolftoerusting. Kommersiële apparaat vir die meet van diëlektriese eienskappe is nie wyd beskikbaar nie en word gewoonlik "binnenshuis" ontwikkel. Die huishoudelike mikrogolfoond magnetron is geredelik beskikbaar en kan in prototipe mikrogolfstelsels gebruik word, maar toevoegers geskik vir spesifieke gebruike moet ontwikkel word. Hierdie proefskrif dek drie hoofgebiede, naamlik: diëlektriese metingsapparaat, mikrogolftoevoegers en smoorders, en die droging van hout. Die eerste deel van die proefskrif handeloor vier diëlektriese metingsapparate, een kommersiëel en die ander "binnenshuis". Die ontwerp en kalibrasie van die "binnenshuis" apparate word aangebied. 'n Tussenvergelyking van die verrigtinge van die vier apparate word gedoen deur die meting van baie bekende diëlektrikums: teflon en perspex. Die mees gerieflike apparaat word gebruik vir die meet van die diëlektriese eienskappe van hout teen verskillend voginhoude. Die tweede deel dek die ontwerp van 'n smoorder en 'n mikrogolf toevoeger wat deur 'n gegleufde golfgeleier gevoer word. Die ontwerp van die gegleufde golfgeleier word beide met en sonder wedersydse koppeling tussen die gleuwe, analities gedoen. 'n Semi-empiriese ontwerp wat van 'n eindige-element pakket gebruik maak, is onafhanklik van die analitiese benadering gedoen. Die resultate word dan vergelyk. Die smoorder word deur 'n prosedure wat "de-embedding" vermy, streng gekarakteriseer. Die derde en laaste afdeling behandel die eksperimentele droging van hout binne die toevoeger. Simulasies en verhittingspatrone van die hout wat gedroog word, sowel as die "mock-up(model van die voorgestelde)" nywerheids houtdroogkamer, word gegee.

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Hartley, Jon. "Simultaneous structural and dielectric measurement of ammonia storage materials." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/89378/.

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The principal aims of this thesis are to design, build and experiment with simultaneous measurement systems, designed to measure ammonia adsorption in a wide range of sample materials. These simultaneous measurement systems will integrate dielectric spectroscopy methods with structural analysis techniques in order to obtain a more complete understanding of the dynamic adsorption processes that occur. Some of the new and most promising materials for ammonia storage applications are tested in this thesis in order to understand the possible strengths and weaknesses that these materials have in becoming used in real world applications. Dielectric spectroscopy in this thesis is achieved by using microwave resonant structures. These devices measure permittivity, dielectric losses and electrical conduction by way of the cavity perturbation technique. Structural analysis is conducted by way of neutron and X-ray diffraction, both of these measurement techniques give insight into the crystal structure of materials. With these two measurement techniques, changes in bulk material properties (measured from the dielectric spectroscopy) can be compared and contrasted with changes in the crystal structure (measured from the diffraction techniques). The materials tested within the simultaneous measurement systems were alkali earth and transition metal halides. On introducing gaseous ammonia to these materials, the dielectric properties and molecular structure changed. Using the combined information from multiple measurement techniques, a wide range of physical phenomena was able to be observed and analysed. This included assessment of the total amount of ammonia adsorbed, the amount of chemisorbed ammonia to physisorbed ammonia and if the ammoniated material was stable after the ammoniation process. Phase transformations involving coordination geometry were observed, as well as suppression of hole conduction processes due to ammoniation.

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Seligman, Jeffrey M. "Spectral Characterization of Dielectric Materials Using Terahertz Measurement Systems." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/566237.

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The performance of modern high frequency components and electronic systems are often limited by the properties of the materials from which they are made. Over the past decade, there has been an increased emphasis on the development of new, high performance dielectrics for use in high frequency systems. The development of these materials requires novel broadband characterization, instrumentation, and extraction techniques, from which models can be formulated. For this project several types of dielectric sheets were characterized at terahertz (THz) frequencies using quasi-optical (free-space) techniques. These measurement systems included a Fourier Transform Spectrometer (FTS, scalar), a Time Domain Spectrometer (TDS, vector), a Scalar Network Analyzer (SNA), and a THz Vector Network Analyzer (VNA). Using these instruments the THz spectral characteristics of dielectric samples were obtained. Polarization based anisotropy was observed in many of the materials measured using vector systems. The TDS was the most informative and flexible instrument for dielectric characterization at THz frequencies. To our knowledge, this is the first such comprehensive study to be performed. Anisotropy effects within materials that do not come into play at microwave frequencies (e.g. ~10 GHz) were found, in many cases, to increase measured losses at THz frequencies by up to an order of magnitude. The frequency dependent properties obtained during the course of this study included loss tangent, permittivity (index of refraction), and dielectric constant. The results were largely consistent between all the different systems and correlated closely to manufacturer specifications over a wide frequency range (325 GHz-1.5 THz). Anisotropic behavior was observed for some of the materials. Non-destructive evaluation and testing (NDE/NDT) techniques were used throughout. A precision test fixture was developed to accomplish these measurements. Time delay, insertion loss, and S-parameters were measured directly, from which loss tangent, index of refraction, and permittivity was extracted. The test materials were low-loss dielectric slabs ranging in thickness from 1-60 mils. The substrate sheets were PTFE, fiberglass, and epoxy-ceramic composite substrates. The other group was polyethylene plastic sheets (LDPE/HDPE/UMHW) and 3D printer Photopolymers. The results were verified by using several online THz spectral databases and compared to manufacturer data sheets. Permittivity and loss of some of the test samples varied as a function of polarization angle. 0 - 90 degrees of rotation were tested (i.e., H-V, and 45 degrees polarization). Inter-molecular scattering in the composite materials raised the loss considerably. This effect was verified. Standard, well documented, material types were selected for the project for best comparison. These techniques can also be applied to analyze newer substances such as nanodielectrics.

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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.

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Hayakawa, N., M. Nagino, H. Kojima, M. Goto, T. Takahashi, K. Yasuda, and H. Okubo. "Dielectric characteristics of HTS cables based on partial discharge measurement." IEEE, 2005. http://hdl.handle.net/2237/6772.

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Miller, Michael Larry. "On-line conversion measurement during solution polymerization via dielectric sensors." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/11024.

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Smith, Paula Kay. "Characterizing Dielectric Tensors of Anisotropic Materials From a Single Measurement." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293464.

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Ellipsometry techniques look at changes in polarization states to measure optical properties of thin film materials. A beam reflected from a substrate measures the real and imaginary parts of the index of the material represented as n and k, respectively. Measuring the substrate at several angles gives additional information that can be used to measure multilayer thin film stacks. However, the outstanding problem in standard ellipsometry is that it uses a limited number of incident polarization states (s and p). This limits the technique to isotropic materials. The technique discussed in this paper extends the standard process to measure anisotropic materials by using a larger set of incident polarization states. By using a polarimeter to generate several incident polarization states and measure the polarization properties of the sample, ellipsometry can be performed on biaxial materials.Use of an optimization algorithm in conjunction with biaxial ellipsometry can more accurately determine the dielectric tensor of individual layers in multilayer structures. Biaxial ellipsometry is a technique that measures the dielectric tensors of a biaxial substrate, single-layer thin film, or multi-layer structure. The dielectric tensor of a biaxial material consists of the real and imaginary parts of the three orthogonal principal indices (nₓ + ikₓ, n(y) +ik(y) and n(z) + ik(z)) as well as three Euler angles (α, β, and γ) to describe its orientation. The method utilized in this work measures an angle-of-incidence Mueller matrix from a Mueller matrix imaging polarimeter equipped with a pair of microscope objectives that have low polarization properties. To accurately determine the dielectric tensors for multilayer samples, the angle-of-incidence Mueller matrix images are collected for multiple wavelengths. This is done in either a transmission mode or a reflection mode, each incorporates an appropriate dispersion model. Given approximate a priori knowledge of the dielectric tensor and film thickness, a Jones reflectivity matrix is calculated by solving Maxwell's equations at each surface. Converting the Jones matrix into a Mueller matrix provides a starting point for optimization. An optimization algorithm then finds the best fit dielectric tensor based on the measured angle-of-incidence Mueller matrix image. This process can be applied to polarizing materials, birefringent crystals and the multilayer structures of liquid crystal displays. In particular, the need for such accuracy in liquid crystal displays is growing as their applications in industry evolve.

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Jazayeri, Sina. "Measurement and monitoring of moisture content in timber and investigations of moisture gradients using dielectric measurements." Thesis, University of Bedfordshire, 1999. http://hdl.handle.net/10547/622156.

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This thesis addresses various issues in connection with the measurement of moisture content in timber. The early parts include long term experimentally based studies which culminated in producing recommendations to existing British Standards for equilibrium moisture content (EMC) of timber in internal environments. Findings consistently showed lower EMCs than existing recommended values; these are believed to be caused by socio-economic factors. Intermediate sections of the thesis continue with tests on electrical methods of moisture content measurement to establish a basis for comparability and the claimed accuracy of currently available moisture meters in the market. To this end, the performance of a wide range of resistance-type moisture meters in worldwide use was critically investigated under laboratory conditions - it was established that even under the strict controlled conditions of the study, large discrepancies are not uncommon (as great as 13% moisture content difference was observed). While some instruments consistently underestimated, others overestimated under identical conditions. Lack of agreed standards for species corrections and temperature correction factors were found to be the main cause of disagreement between the meters. Further discussions include the layout for a proposed standard in which agreed values for species and temperature correction factors would be established. In the latter part of the thesis moisture gradients in timber, the causes and the current methods of assessment are discussed. In particular, the performance of a leading brand capacitance-type moisture meter was systematically investigated both in the absence and in the presence of predetermined moisture gradients. It was established that moisture gradients severely affect the measured moisture content. A computer controlled capacitance measurement system based on resonance detection was developed to initially replicate the behaviour of conventional capacitance-type moisture meters, and to further investigate possible moisture gradient detection protocols. Two electrode designs were used in order to investigate methods by which moisture gradients could be detected. It was shown that a multi-plate electrode can be used to detect moisture gradients in timber to depths of at least 10 mm.

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Langham, Conway David. "Cryogenic sapphire dielectric resonators as microwave frequency standards : development and performance." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364164.

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Lee, Kyeonghwan. "A dielectric permittivity sensor for simultaneous measurement of multiple soil properties /." Search for this dissertation online, 2005. http://www.lib.umi.com/cr/ksu/main.

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Donhauser, Norbert. "Electromagnetic measurement of bubble velocity in two-phase dielectric fluid flow." Thesis, Cranfield University, 1997. http://hdl.handle.net/1826/3918.

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This thesis deals with the theoretical and experimental investigation of two-phase flow for a dielectric liquid electromagneticf lowmeter. So far only limited investigationsi nto the possibleu se of electromagneticf lowmeters for multiphasef low measuremenht ave been made. These have been restricted to electromagnetic flowmeters designed for conducting water based (electrolytic) fluids. The possibility of designing electromagnetic flowmeters for use with insulating (dielectric) fluids such as oil and petrol has been existed for some years. However the measuremenot f two-phase flow of insulating fluids using electromagnetic flowmeters and the application of this knowledge to the measurement of the separate phases has not yet been a subject for research. An analytical model is developed which evaluates a transformer signal that is produced on the electrodes when a bubble unbalances eddy currents while it passes through the meter. The shape and magnitude of this signal for various positions in the pipe cross-section is investigated. The behaviour of this transformer signal for various electrode shapes is studied as well and it is found that when using large area electrodes the position of the amplitude along the pipe axis remains almost constant. For measuring the speed of bubbles passing through the meter a frequency analysis is carried out and shows that the peak frequency of the signal is proportional to the velocity of the bubbles. A flowmeter is built to carry out experimental work. The first sets of experiments are carried out with plastic beads fixed on a thin string which is attached around two wheels. The speed of the beads is adjusted by an electromotor which powered one wheel. In a second experimental design gas bubbles are injected in a vertical pipe which is filled with dielectric oil. Both types of experiments exhibit the behaviour predicted in theoretical analysis.

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Ogunlade, Olumide. "Measurement of the microwave dielectric properties of liquids using waveguide structures." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556018.

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A variety of waveguide structures have been analysed for the measurement of the complex dielectric permittivity of liquids. Mode matching techniques are im- plemented to solve the forward problem of computing the scattering parameters for a sample of known permittivity filling a rectangular metal waveguide. Three different sample geometries are used. In the first, the liquid and the sample holder completely fill the waveguide cross section. As a result, only the dominant waveguide modes are matched across the discontinuity interface and an exact an- alytical relation between the S parameters and permittivity can be written. The second and third configurations are concentric cylinders and rectangles respec- tively, partially filling a metal waveguide, hence higher order modes are taken into account in the formulation. For the partially filled rectangular sample, a generalised scattering matrix method to obtain the overall scattering parameters due to the several discontinuity regions. Iterative methods are then introduced to solve the inverse problem of recover- ing the unknown permittivity from simulated or measured scattering parameters. For the partially filled waveguides, because an exact analytical relation does not exist, objective( error) functions are defined and minimized. The partially filled rectangular sample case is extended to obtain the resonant frequency and qual- ity factor of a dielectric loaded resonant cavity, and the results compared to the approximation normally used for the cavity perturbation technique. Finally, a rectangular dielectric waveguide method for liquid measurements was developed. This method has a treatment similar to the well known free space tech- niques. It has a distinct advantage of relaxing the strict requirements of sample dimension associated with metal waveguides, especially at higher frequencies.

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Petersson, L. E. Rickard. "Analysis of two problems related to a focused beam measurement system." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/13545.

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Marques, Duarte da Paz Ana Marta. "Water content measurement in woody biomass : using dielectric constant at radio frequencies." Licentiate thesis, Mälardalen University, School of Sustainable Development of Society and Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-963.

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The will for replacement of fossil fuels increased the use of woody biomass as fuel in heating and power plants. An important parameter for the use woody biomass as fuel is the water content of biomass as it influences the heating value and thereby the combustion control and pricing. Currently, water content is determined using the gravimetric method by drying samples in an oven. This method is neither fast nor representative, as the water content can vary largely in different parts of the container which raised the need to develop sensors that are able to measure water content of biomass on-line and in a representative way.This thesis presents results from studies on the measurement of water content of woody biomass with radio frequency. Included are the study on the influence of temperature in the measurements, the use of dielectric mixing models to explain the dielectric behavior of woody biomass and the application of the measurement principle to full-scale.

It was found that varying temperature between 1 and 62 °C did not influence the prediction of water content in biomass. It was possible to explain the behavior of the dielectric constant of woody biomass with a model with physical basis using empirically obtained parameters. Application of the principle to full-scale had positive results but larger prediction error than laboratory-scale measurements.

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Qureshi, Rustam Mustafa. "Ring Resonator with single gap for Measurement of Dielectric Constants of Materials." Thesis, Högskolan i Gävle, Radio Center Gävle, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-15207.

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The significance of calculating and measuring dielectric constant is important for all the fields of study and research from biological science to electronics and telecommunication. It gives a better characterization of the material and helps to design the accurate system, and aside these two functions, it has numerous uses. Owing to its huge expediency, various measurement methods of dielectric constant of materials have been developed by scientists and engineers over the years. Each method has its limitations which affect the accuracy of the measurement; these limitations range from frequency, temperature, measurement environment to material under test. In this research work, we measured the resonant frequency of the ring resonator using different materials and then we measured the dielectric constant of different materials by using that resonant frequency. We discussed different common methods of measuring dielectric constant and the most accurate one, the resonant method, was chosen and driven upon .The project was done by making a mathematical analysis for the geometry of the ring resonator, wrote MATLAB script for the measurement of the resonant frequency, later designed and simulated in HFSS to obtain results which would be comparable to ones obtained in laboratory measurements. The ring was fabricated and taken to the laboratory for measurement of the resonant frequency for measuring dielectric constant of different materials; two monopole antennae were connected to the two ports of a vector network analyzer with one antenna serving as the transmitter and the other serving as the receiver. When we used the MUT in the gap of the ring resonator we saw frequency shift in the resonant frequency and we noted that resonant frequency. The resonant frequencies obtained were compared with the geometric parameters of the ring resonator and that of the MUT in an equation written into MATLAB script; this equation was used to extract the dielectric constant of the MUT and then we calculated the dielectric constant by using the resonant frequency of the MUT.

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Popplestone, A. "An instrument for fast dielectric measurement at audio and sub-audio frequencies." Thesis, Swansea University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638552.

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Greenacre, Neil Robert. "Measurement of the high temperature dielectric properties of ceramics at microwave frequencies." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339644.

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Measurements of the high temperature dielectric properties of ceramic materials at microwave frequencies have been made using two different experimental techniques.Data has been collected at frequencies from O.2GHz to 4.0GHz and for sample temperatures up to 1200°C. Detailed cross checking of the high temperature dielectric data obtained by the two techniques has been carried out with the help of other laboratories worldwide. An investigation of the applicability of dielectric mixture equations to practical measurement techniques is reported. The most reliabl~ estimates of permittivity were given by the Landau-Lifshitz, Looyenga equation or by a cube root extrapolation technique.Permittivity data obtained for a series of yttria stabilised zirconia samples, three differently processed silicon nitride samples and ten related glass compositions are presented. Analysis of the frequency and temperature dependence of both components of complex permittivity has been undertaken· in an attempt to identify the physical origins of the dielectric loss mechanisms. For the yttria doped zirconia samples results indicate two distinct loss mechanisms dominant over different temperature ranges. Below approximately 950K a hopping model involving short range motion of oxygen vacancies around fixed dopant ions is proposed. Above 950K thermally activated quantum mechanical tunneling of electrons is suggested as the dominant mechanism. A single loss mechanism for the entire temperature range involving the lattice loss of the silicon nitride network itself is indicated from the measurements of the hot pressed and pressureless sintered silicon nitride samples. For the reaction bonded silicon nitride samples there is evidence of a second loss mechanism due to additional ion impurities above 1410K. The measurements on the oxide glass systems add support to the belief that + 1 charged metal ions will dominate the dielectric properties of glass systems when present. The loss process has an increasing activation energy with increasing temperature which is seen to be consistent with ionic motion within the previously proposed random potential energy model. Differences in the complex permittivity with composition are attributed to variation in ionic size and metal ion-oxygen ion bond strength.

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Fikar, Pavel. "Dielectrophoretic cytometry for measurement of live cell dielectric signatures on population level." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1038/document.

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La cytométrie en flux en association avec la coloration et le marquage d'anticorps présente l'un des outils les plus précieux en biotechnologie actuelle fournissant des informations sur l'hétérogénéité des populations cellulaires, la taille et le volume des cellules, ainsi que l'expression de certaines molécules de surface et intracellulaires. L'augmentation du coût et la difficulté fondamentale de ces méthodes, cependant, sont attribués à l'exigence des molécules de marquage de surface. Diélectrophorèse (DEP) a été identifiée comme alternative sans marquage prometteuse. Cette thèse porte sur l'amélioration des technologies basée sur les DEP actuelles, et le développement d'une nouvelle méthode pour aborder les questions de cytometrie diélectrophorétique (DEP) permettant la mesure probabiliste des signatures diélectriques (DE) de cellules au niveau d’une population, ainsi que de permettre l'identification de biomarqueurs fiables pour les changements cellulaires.Tout d'abord, les améliorations de la cytométrie DEP sur la translation de cellules latérales induites par DEP sont explorées par fabrication. Un système de tri cellulaire benchmark microfluidique est présenté, et l'effet des désalignements des microcanaux sur les topologies des électrodes des cellules DEP vivantes est discuté. Un modèle de S. cerevisiae est présenté et validé expérimentalement dans des dispositifs microfluidiques fabriqués. Un nouveau procédé de fabrication permettant le prototypage rapide de dispositifs microfluidiques avec des électrodes intégrées bien alignées est présenté. Des dispositifs identiques ont été fabriqués avec des procédés standards de lithographie douce PDMS. Selon l'étude benchmark, la procédure standard PDMS est tombée bien en dessous de la gamme nécessaire pour le tri des cellules par DEP. Le temps de fabrication et les coûts de la méthode proposée se sont révélés être à peu près les mêmes.Deuxièmement, une nouvelle méthode appelée cytométrie DEP distribuée (2DEP cytométrie) a été développée. Elle utilise une translation verticale de cellules induite par effet de DEP en liaison avec la vélocimétrie par image de particules (PIV) afin de mesurer la répartition probabiliste de forces DEP sur une population cellulaire entière. La méthode a été intégrée dans un dispositif microfluidique avec des électrodes intégrées. Les cellules passant à travers le micro-canal sont sollicitées par des forces de sédimentation, tandis que les forces DEP soit s’opposent à la sédimentation, prennent en charge la sédimentation, ou aucun des deux, en fonction des signatures DE des cellules. Les hauteurs à laquelle les cellules se stabilisent correspondent à leur signature DE et sont mesurées indirectement en utilisant PIV.Les données expérimentales quantifient la signature DE d'une population de S. cerevisiae et la lignée cellulaire human immortalise leucemie myeloide K562. Tout d'abord, l'effet de la surexpression de certaines protéines membranaires a été étudié dans des cellules S. cerevisiae. La répartition mesurée des forces DEP a été comparée à la population de cellules exprimant une protéine cytoplasmique au même taux. Deuxièmement, 2DEP cytométrie a été appliquée à la lignée cellulaire K562. Les effets de la réponse à un stress provoqué par divers inducteurs sur la signature DE de la population cellulaire ont été analysées.Enfin, l'analyse statistique des données définies estimation par noyau ajustées pour surmonter la nature finie des données mesurées. En combinaison avec des spectres en distance de Wasserstein, notés signatures Wasserstein, ont été quantifiés et liée à certains changements cellulaires. Ces signatures peuvent être utilisées comme marqueurs biologiques fiables pour certains changements cellulaires.En conclusion, 2DEP cytométrie a montré être suffisamment sensible pour identifier certains changements d’états cellulaires. Le nouveau dispositif 2DEP cytométrie est donc une alternative prometteuse à la cytométrie en flux classique
Flow cytometry in combination with staining and antibody labelling presents one of the most valuable tools in current biotechnology providing information about cell population heterogeneity, cell size and volume, as well as expression of certain surface and intracellular molecules. The increased cost and the fundamental difficulty of these methods, however, are attributed to the requirement of the surface marker molecules. Attractive alternatives to flow cytometry are label-free methods, such as micro-filtration, dielectric spectroscopy, and electro-kinetic methods. Out of these methods, dielectrophoresis (DEP) was selected as the most promising approach. This thesis focuses on improvements of current DEP-based technologies, and development and establishment of a new method to address the issues of dielectrophoretic (DEP) cytometry enabling label-free non-invasive probabilistic measurement of cell dielectric (DE) signatures on population level, as well as enabling identification of reliable biomarkers for cell changes.First, improvements of DEP cytometry based on DEP-induced lateral cell translation through fabrication are explored. A benchmark microfluidic live cell sorting system is presented, and the effect of microchannel misalignment above electrode topologies on live cell DEP is discussed in detail. Simplified model of budding S. cerevisiae cell is presented and validated experimentally in fabricated microfluidic devices. A novel fabrication process enabling rapid prototyping of microfluidic devices with well-aligned integrated electrodes is presented and the process flow is described. Identical devices were produced with standard PDMS soft lithography processes. The presented fabrication process significantly improved the alignment of the microstructures. According to the benchmark study, the standard PDMS procedure fell well outside the range required for reasonable cell sorting efficiency. The fabrication time and costs of the proposed methodology were found to be roughly the same.Second, a method called distributed dielectrophoretic cytometry (2DEP cytometry) was developed. It uses a DEP-induced vertical translation of live cells in conjunction with PIV in order to measure probabilistic distribution of live cell DE signatures on an entire cell population. The method was integrated in a microfluidic device with integrated electrodes. Cells passing through the microchannel are acted on by sedimentation forces, while DEP forces either oppose sedimentation, support sedimentation, or neither, depending on the DE signatures of the cells. The heights at which cells stabilize correspond to their DE signature and are measured indirectly using particle image velocimetry (PIV).Experimental data quantify the DE signature of a S. cerevisiae population and Human immortalised myelogenous leukaemia cell line K562. First, the effect of over-expression of certain membrane protein was studied in S. cerevisiae cells. Measured distribution of DEP forces was compared to cell population expressing a cytoplasmic protein at the same rate. Second, 2DEP cytometry was applied to K562 cell line. Effects of stress response triggered by various inducers on the DE signature of the cell population were analysed.Finally, statistical data analysis defined adjusted kernel density estimation to overcome the finite nature of the measured data. In combination with Wasserstein pseudometrics from sampled data, the Wasserstein distance spectra, denoted as Wasserstein signatures, were quantified and linked to certain cell changes. These signatures may be used as reliable biomarkers for cell changes.In conclusion, 2DEP cytometry showed it is sensitive enough to identify certain changes in cell states. The novel 2DEP cytometry device is therefore a promising alternative to conventional flow cytometry

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Appello, Mario. "Real-time measurement of electrical properties during the processing of conductive polymers." Thesis, University of Warwick, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341559.

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Xiang, Dong. "Differential dielectric sensor analysis and experimental investigation of a modular differential dielectric sensor for use in multiphase separation, process measurement and control." Saarbrücken VDM Verlag Dr. Müller, 2008. http://d-nb.info/991258150/04.

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Skidmore, Scott. "Analysis and Optimization of Broadband Measurement Cells for the Characterization of Dielectric Polymer Films." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4224.

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The current techniques and methodologies used in the field of material characterization are well documented and widely accepted as reliable and accurate. However, literature describing these techniques focuses on the algorithms used during material characterization; few studies have reposted on the design of, and the selection criteria for, the test fixtures themselves. This research focuses on the measurement cell with the goal of determining the sensitivity of the measurement cell to the addition of a thin film material. Microstrip and coplanar waveguide were chosen for the analysis, which included three configurations of each transmission line geometry: a reference with no additional thin film material, one with the thin film on top of the conductors and one with the thin film beneath the conductors but on top of the transmission line substrate. The scattering parameters for the reference cell are compared to the scattering parameters of the test cell with the thin film material. The additional thin film material changes the effective dielectric constant of the reference cell; this change is evident in the phase and amplitude of S21. The optimum measurement cell is the one that experiences the greatest change to the effective dielectric constant with the addition of the thin film. Thus the greatest difference in S21 between the reference cell and the test cell is indicative of the reference cell's sensitivity. The figure of merit (FOM) to determine the structure's sensitivity is the integration over frequency of the magnitude of the vector difference of S21. The analysis shows that the double-layered CPW measurement cell was the most sensitive. Once the optimum structure was determined an analysis of the sensitivity of the FOM to changes in the physical and electrical properties of the reference structure was conducted. The most important factors in the selection of the reference cell as evident by the FOM's sensitivity are the substrate to thin film dielectric constant ratio and the CPW conductor aspect ratio to the thin film thickness. In particular, thinner films require a smaller conductor gap while wider gaps are preferable for thicker films. Measurement of four different CPW geometries, each covered in a 300 micron Polydimethylsiloxane thick film, validate the analysis process. The measurement cells differ in the conductor aspect ratio. The values of the measured FOMs trend as predicted by the simulation analysis.

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Apicella, Fernández Sergio. "MEASUREMENT OF DIELECTRIC CONSTANT FOR WATER AND ITS TEMPERATURE DEPENDENCE AT 0 AND 86ºC." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-16383.

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The dielectric properties determine the electrical characteristics of materials. These properties are important for understanding the behavior of materials and how they can interact with each other. Engineers and scientists need to measure these parameters as accurately as possible, and thus be able to integrate them in their designs in a reliably way. Examples of application are dielectrics used in capacitors that have the function of reducing the applied electric field and increase the capacitors´ capacitance. The later can be increased by using dielectrics with high permittivity (dielectric constant) as water which has a dielectric constant of 80 at room temperature (25ºC). Unfortunately water cannot be used alone as dielectric due its capacity to be conductive and has to be combined with other materials. However, this study will focus only on measuring the dielectric properties of water and its temperature dependence. Temperatures chosen for measurements are 0 and 86ºC. Several methods have been studied over the years to measure the dielectric properties of materials, but there are only three possible measurement methods for liquids: coaxial probe, parallel plates and free space method. Comparing the three methods, in our case the free-space method is better because it allows to perform measurements at high temperatures and in hostile environments. These two features are very important, since the water should be measured at 86 ºC and measurements are performed in a RF (Radio Frequency) lab, where interferences due to the electronic devices can affect accuracy in free-space measurements. Hence, the following thesis is based exclusively on analyzing the free-space measurement method for measuring the reflection parameters in dB by using two horn antennas. Both antennas are connected to the Vector Network Analyzer (VNA): one as transmitter and the other as receiver. Reflection parameters are also calculated by introducing the reflection formula for lossless material and a finite length in Matlab. Then, the dielectric constant is extracted by comparing both reflections in dB.

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White, M. P. "Direct measurement of the dielectric virial coefficients of helium from 3 to 17.67 K." Thesis, University of Bristol, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281845.

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Boissonade, Jonathan James. "Direct contact measurement of the dielectric properties of glass ionomer cements for MEMs design." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6321/.

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This investigation was aimed at measuring the changes in dielectric properties of glass ionomer cements during their setting reaction in order to observe if there is a correlation between these properties and the cement curing. Commercial glass ionomer cements were prepared and their setting process was monitored over a 24 hour period using FT-IR and direct contact impedance measurement. An impedance bridge with a dielectric test assembly, based on previous work by Braden et al, was used to measure the dielectric properties of a number of different glass ionomer cements using a simple design. Using the dielectric properties of the glass ionomer cements, it could be possible to develop a micro-electro-mechanical sensor (MEMS) based on this design, which could be implanted into a dental restoration and interrogated remotely. During the curing of the cements examined, the dielectric data collected from the co-planar assembly showed a change in impedance over the course of the setting of the cement, which when compared to FT-IR spectra over the same period, showed a correlation between the dielectric properties and the chemical changes within the cement.

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Li, Xiang, and Yan Jiang. "Design of a Cylindrical Cavity Resonator for Measurements of Electrical Properties of Dielectric Materials." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-7687.

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In microwave communications, the main aspects for affecting the dielectric losses in the materials are relating to the dielectric properties and the radiation frequencies. Normally, the different dielectric materials will lead to the different losses and reflections for microwave frequencies. To evaluate the dielectric properties from the different materials plays an essential role in the microwave engineering. There are many approaches can be used to measure the dielectric materials, e.g. capacitor methods, transmission line methods, cavity resonator methods, open cavity methods and so on. The cavity resonator method is one of the most popular ways for measuring the dielectric materials. In this thesis, some of the techniques will be reviewed, and the TM010 mode cylindrical cavity resonator with perturbation technique will be used for determining the dielectric properties. The design and measurements will be presented in both simulations and practice. With 1.2GHz cavity resonator, in the simulations, the dielectric permittivity for Teflon is measured as 2.09-0.0023i and 2.12-0.0116 in copper cavity and ferromagnetic cavity. Finally the sample is measured as 3.83-0.12i in practice.

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Jabita, Abdul-Nafiu Abiodun. "Design of Singly Split Single Ring Resonator for Measurement of Dielectric Constant of Materials using Resonant Method." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-14747.

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Scientists and engineers measure dielectric constant because it gives them better understanding of materials and helps them to know how to integrate these materials into their design processes;it also helps them to shorten design life cycle,and aside these two functions,it has numerous uses all of which cannot be enumerated in this section.Owing to its usefulness,various measurement methods of dielectric constant of materials have been developed over the years.Each method has its limitations which affect the accuracy of the measurement;these limitations range from frequency,temperature,and mearsurement environment to material under test. In this thesis,four most common methods of measuring dielectric constant were discussed and the most accurate one,the resonant method,was chosen and worked on .The project was executed by making a mathematical analysis of the ring resonator which was later simulated in HFSS to get results which would be comparable to ones obtained in laboratory measurements. The ring was fabricated and taken to the laboratory for measurement.Two monopole antennas were connected to the two ports of a VNA with one antenna serving as the transmitter and the other serving as the receiver. The resonant frequencies obtained were combined with the geometric parameters of the ring resonator and that of the MUT in equations written into MATLAB scripts;this equations were used to extract the dielectric constant of the MUT.

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Yang, Xu. "Enhancements to dielectric response measurements of oil-paper insulation for online and offline applications." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/82373/1/Xu_Yang_Thesis.pdf.

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The research introduces a promising technique for monitoring the degradation status of oil-paper insulation systems of large power transformers in an online mode and innovative enhancements are also made on the existing offline measurements, which afford more direct understanding of the insulation degradation process. Further, these techniques benefit from a quick measurement owing to the chirp waveform signal application. The techniques are improved and developed on the basis of measuring the impedance response of insulation systems. The feasibility and validity of the techniques was supported by the extensive simulation works as well as experimental investigations.

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Birkelund, Bendik Jørgensen. "Investigation of Dielectric Response Measurement as a Tool to Detect Copper Sulphide on Insulation Paper." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12876.

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Several power transformers has, during the last two decades, broken down due to the copper sulphideproblem. Corrosive sulphur reacts with the copper conductor contaminating the surroundinginsulating paper. To this day there are no reliable nondestructive methods to detect copper sulphidecontamination in a power transformer.Dielectric frequency measurement is a nondestructive tool used in the transformer industry. Themeasurements can give important information about the condition of the transformer insulation. Inthis master thesis the usage of dielectric frequency measurement as a tool to detect copper sulphideon insulation paper has been investigated.The task has been divided into two subtasks:Subtask I: Develop and test different methods to create and classify copper sulphide contamination on paper samples.Subtask II: Examine the dielectric frequency response of the contaminated samples as a function of copper sulphideSolution and results for Subtask IFor sample creation two methods were used:Creating samples out of paper strips taken from existing transformersGrowing copper sulphide on paper in the laboratory for three, ffve, eleven and fourteen daysFor copper sulphide classiffcation three methods were used:Resistance measurementArea percentage calculationClassiffcation by the number of days grown.For sample creation the growth of copper sulphide samples seemed to be the better choice as the gapsbetween the samples of strips gave large uncertainties in the dielectric frequency response. The growthvaried in some extent and days of growth some times became insuffcient in classifying degree of coppersulphide. Good connection between the copper and paper may be an important factor, and the sizeof the samples is recommended to be kept small. For all samples, contamination got heaviest at theedge. For the samples grown for fourteen days the paper became too fragile for dielectric frequencytesting.The resistance measurement classiffcation method seemed to be the best choice, as it could copewith large variations in the contamination. The area percentage calculation method worked undervery limiting conditions as the contamination had to be of a certain brightness level and with lowvariations in colour. The classiffcation due to days of growth came too short as the contaminationbetween ffve and seven days were not that signiffcant. Larger time intervals can be a solution.Solutions and Results from Subtask IIDielectric frequency measurements were tested with two separate equipments:The Insulation Diagnostic Analyser: Frequency range: 1mHz-1kHz.The Alpha-Analyser: Frequency range: 100Hz-1MHzAll tests where performed in equilibrium with air humidity at the time of testing.The gaps between the strips, used in the samples, gave a substantial effect to the dielectric frequencyresponse. This effect was clearest at the lower frequencies, but some effect can also be seen inthe higher region. At the lower frequencies the results gave no indication of any effect in the dielectricresponse due to copper sulphide. However, the gap effect may have concealed the effect, and testingwithout gaps is recommended.At the higher frequencies the grown copper sulphide samples gave some variations in the dielectricfrequency response. The variations in results also occurred between samples with the same creationconditions. This may still indicate a relation between copper sulphide and dielectric response at higherfrequencies. Even with the large deviations there were, at frequencies above 100kHz, a steeper increasein losses for the contaminated samples. Of the grown samples created only samples of ffve and sevendays growth were tested. This gives a limited research foundation and further investigation is needed.Conclusions and Future WorkIn general there might be a correlation between copper sulphide and dielectric frequency measurement.Growing samples has turned out to work well as the test object provider. By combining days of growthwith resistance measurements the classiffcation of the contamination should be suffcient. However,more research is absolutely needed and some suggestions for further work are as follows:Dry the samples to minimise the water effect on the dielectric frequency measurement.Creating a new smaller sample cell for the Insulation Diagnostic Analyser, so the sample size can be reduced and sample without gaps can be run in the lower frequency range.Increase the time gap between the samples grown to get larger differences in contamination, and reduce the effect of variations.Reducing the temperature may be a way to increase days of growth. However, in this case more research on the temperature dependencies of copper sulphide growth is needed.

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Holden, Simon John. "The measurement of the dielectric properties of mammalian tissue in-vivo up to 20.05 GHZ." Thesis, Brunel University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435754.

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Illias, Hazlee Azil. "Measurement and simulation of partial discharges within a spherical cavity in a solid dielectric material." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/194921/.

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For high voltage components, the measurement of partial discharge (PD) is used in the performance assessment of an insulation system. Through modelling the PD process, a better understanding of the phenomenon may be attained. In this work, a model for a spherical cavity within a homogeneous dielectric material has been developed using Finite Element Analysis (FEA) software in parallel with MATLAB programming code. The model has been used to study the effect of various applied stresses and cavity conditions on PD activity and also the electric field and temperature distributions within the cavity. The experimental measurement of PD activity within a spherical cavity has also been undertaken. The measurements were performed for different amplitudes and frequencies of the applied voltage, a range of spherical cavity sizes and temperature variation of the material. The obtained results show that PD is strongly influenced by various conditions of the cavity and applied stress. The cycle to cycle behaviour of PD events, discharge phase and magnitude distributions, numbers of PDs per cycle, total charge magnitude per cycle, mean charge magnitude and maximum charge magnitude for each experiment have been obtained and analysed. The simulation results from the PD model have been compared with the measurement results. It is found that certain model parameters are dependent on the applied stress and cavity conditions. Parameters that clearly affect PD activity can be readily identifed. These parameters include; the effective charge decay time constant, the cavity surface conductivity, the initial electron generation rate, the inception field, the extinction field and the temperature decay time constant in the cavity. The infuences of surface charge decay through conduction along the cavity wall and temperature and pressure change in the cavity on PD activity have also been studied

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Amiet, Andrew. "Free space permittivity and permeability measurements at microwave frequencies." Monash University, Dept. of Electrical and Computer Systems Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9529.

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Bhuiya, Md Omar Faruqe. "Design and optimization of a stripline resonator sensor for measurement of rubber thickness." Akron, OH : University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1164650416.

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Thesis (M.S.)--University of Akron, Dept. of Electrical Engineering, 2006.
"December, 2006." Title from electronic thesis title page (viewed 10/17/2007) Advisor, Nathan Ida; Committee members, James Grover, George C. Giakos; Department Chair, J. Alexis De Abreu Garcia; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

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Worley, Stacy K. "Bearing failure detection in farm machinery using low-cost acoustic techniques." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06302009-040529/.

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41

Jackson, Mitchell L. "Investigation of Adhesive and Electrical Performance of Waterborne Epoxies for Interlayer Dielectric Material." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/40359.

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The primary differences between the solventborne and waterborne epoxy printed circuit board (PCB) impregnating resins arise from the distinct physical compositions and drying characteristics of the polymer solution and the latex emulsion. The presence of residual surfactant from the waterborne epoxy emulsion poses a concern for dielectric performance and adhesive durability. Another problem involves the crystallization of insoluble solid dicyandiamide (DICY), which is significantly different in morphology than that found in solution cast resins. A two-stage drying model was employed to gain a better understanding the drying and coalescence processes. The process of surface DICY crystal formation during the drying of glass prepreg sheet was related to a threshold concentration of the curing agent in the impregnating latex resin formulation. Conditions favoring faster drying lead to the rapid formation of a coalesced skin layer of latex resin, thereby trapping the curing agent in the bulk and reducing the surface deposition of DICY by percolating water. Surfactant is believed to remain concentrated in a receding wet zone until it is driven to the surfaces of the glass fibers upon the completion of drying. The copper foil/laminate interface was evaluated by a 90Â° peel test as part of two different studies: an analysis of the viscoelastic response of the interface during peel and a study of the thermal durability of the copper/laminate interfacial peel strength. The surfactant acted as a plasticizer to toughen the fiber/matrix interphase, resulting in larger observed peel strengths in the latex resin impregnated materials relative to the solventborne system. Surfactant segregated to the fiber surface during coalescence to form a plasticized fiber/matrix interphase; surfactant migrated into the bulk during postcure to yield a more homogeneously plasticized epoxy matrix. Dielectric measurements of neat resin and laminate materials revealed that the dielectric constants of the model resin-impregnated laminates met the performance criteria for PCB substrates of their class, regardless of surfactant content. Overall, the adhesive performance, adhesive durability, and dielectric properties of PCB systems fabricated with model latex epoxy resin, containing native surfactant (5 wt %), met or exceeded the performance of an equivalent solventborne resin impregnated system.
Ph. D.

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42

Liu, Tao. "Determination of three dimensional refractive indices and absorption coefficients of anisotropic polymer films with prism wave-guide coupler." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/8601.

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Yuen, David J. (David Joseph). "Measurement of high frequency dielectric constant and conductivity of fluids and fluid-saturated rocks at high pressure." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/84199.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.
Title as it appears in the M.I.T. Graduate List, June 1990: High-frequency dielectric constant and conductivity of fluids and fluid-saturated rocks at high pressure.
Includes bibliographical references (leaves 124-127).
by David J. Yuen.
M.S.

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44

Funes, Freddy Raynard 1981. "Measurement of a new micro supercapacitor and the creation of its dielectric medium y Freddy Raynard Funes." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32817.

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Lundberg, Anders. "Study of different methodologies to determine relative dielectric constant of given substrate using fabrication, modelling and measurement strategies." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-84338.

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In this thesis, different methods for measuring the relative dielectric constant is investigated using simulations and experimental approaches. The first method is known as the S-parameter inversion method. In this method formulae is used to calculate the characteristic impedance of the microstrip line from measured S-parameters. To calculate the value of relative dielectric constant, four expressions for the microstrip line that relate the characteristic impedance to the relative dielectric constant were used. Second method uses an implementation of a band-pass filter and is commonly known as the band-pass filter method. In this method, a band-pass microstrip filter was designed using a predicted relative dielectric constant value. Center frequency of the band-pass filter is chosen to be at the frequency of interest, since relative dielectric constant will be determined around this frequency. The designed band-pass filter was manufactured and the frequency response was measured. To determine the true relative dielectric constant one changes the relative dielectric constant parameter used in the simulation until it matches the measured response of the manufactured PCB. Third method is called the quarter wavelength stub method. It uses implementations of a microstrip quarter wavelength stub because it resonance at different frequencies. The relative dielectric constant is determined using the frequencies on which the reflection occurred. In the fourth method, called the two microstrip line method, two lines of different lengths were designed and the phase difference between the propagating waves were measured. The phase difference and difference in length of the two lines is then used to calculate the relative dielectric constant. The thesis shows that a majority of the methods generates a similar result, thus indicates that they are suitable to determine the relative dielectric constant of any given substrate. The two methods that gave the most accurate results are the quarter wavelength stub method and the band-pass filter method. S-parameter inversion method is the method that has high variations in the results. Since the characteristic impedance that is calculated using the S-parameters are sensitive towards any sort of disturbances. The resulting relative dielectric constant aren't within the expected range for FR-4 both higher and lower values were obtained. The band-pass filter method gives the most accurate results of the methods. As the resulting relative dielectric constant are within the expected range for FR-4. Quarter wavelength stub method gives the results of the relative dielectric constant that are within the expected values of FR-4 and the variation is moderate. Two microstrip line method shows deviations in the results and has non-linearity as well. This is probably coming due to resonance of the line that gives rise to a phase change. This method is also acceptable since the results of the relative dielectric constant are within the expected range for FR-4.

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Okubo, Hitoshi, and Naoki Hayakawa. "A novel technique for partial discharge and breakdown investigation based on current pulse waveform analysis." IEEE, 2005. http://hdl.handle.net/2237/6748.

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Wutikuer, Otkur. "Fabrication and Characterization of 4H-SiC MOS Capacitors with Different Dielectric Layer Treatments." Thesis, Linköpings universitet, Halvledarmaterial, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-144984.

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4H-SiC based Metal-Oxide Semiconductor(MOS) capacitors are promising key components for next generation power devices. For high frequency power applications, however, there is a major drawback of this type of devices, i.e. they have low inversion channel mobility that consequently affects the switching operation in MOS Field-Effect Transistors (MOSFETs). Carbon clusters or excess carbon atoms in the interface between the dielectric layer and SiC is commonly considered to be the carrier trapping and scattering centers that lower the carrier channel mobility. Based on the previous work in the research group, a new fabrication process for forming the dielectric layer with a lower density of the trap states is investigated. The process consists of standard semiconductor cleaning, pre-treatments, pre-oxidation, plasma enhanced chemical vapor deposition (PECVD) and post oxidation annealing. I-V measurements of the dielectric strength showed that the resulting layers can sustain proper working condition under an electric field of at least 5MV/cm. C-V characteristics measurements provided the evidence that the proposed method can effectively reduce the interfacial states, which are main culprit for a large flat band voltage shift of C-V characteristics, in particular under annealing at 900°C in nitrogen atmosphere.

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Huang, Chun-Jen, and 黃俊仁. "The research of dielectric measurement technique." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/72207657352320202325.

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碩士
國立中央大學
電機工程研究所
90
Abstract In this paper, we are concerned with techniques for measuring the dielectric constant. We use vector network analyzer in measuring, so we reviewed the calibration of VNA before measuring. In this paper, there are two techniques in measuring. The objects we measure are low loss dielectrics. One of the two techniques is NRW method. We correct the results with genetic algorithms (GA). After using GA we can improve the accuracy of our results. The other of the two techniques, we use the ring resonator. Basically, the dielectric constants are to be inferred from the shift of the resonant frequency and the quality factor of the resonator after placing the resonator in contact with medium. Finally, we make the sensitivity analysis for the results.

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49

Chiou, Yih-Shyh, and 邱奕世. "The Development of Dielectric Measurement Technique." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/17064802515163877788.

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碩士
國立中央大學
電機工程研究所
89
ABSTRACT A practical technique for measuring the complex dielectric constant, complex permeability and the thickness of materials is developed. To obtain these parameters, a rectangular-cross- sectioned device under test is placed in a rectangular waveguide, where the magnitude and phase of the reflection and transmission coefficients are measured over the desired frequency band. An accurate calibration technique is also established during the measurement using a vector network analyzer. Besides, a better genetic algorithm is applied to retrieve desired parameters from the measured data, which directly represents complex number chromosomes and uses decimal linear crossover without crossover site, instead of using binary coding and binary crossover in conventional genetic algorithm. Such approach avoids coding and works directly with real/complex numbers. With the flexible genetic algorithm, therefore, the programming is simplified and the computation efficiency is enhanced.

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50

Zhang, Kai-Cheng, and 張凱程. "Dielectric constants measurement of zinc nanoparticles implemented with a dielectric rod cavity." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/79113062764516518031.

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Dissertations / Theses on the topic 'Dielectric measurement'

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