Дисертації з теми "Dielectric penetration"

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Colton, Jonathan; Committee Member: Schultz, John; Committee Member: Zhou, Min. Part of the SMARTech Electronic Thesis and Dissertation Collection.

В даній роботі розглянуто питання загальних теоретичних відомостей з складених та тонких діелектричних резонаторів та методів вимірювання вимірювання НВЧ параметрів діелектричних матеріалів. Досліджено метод тонкого діелектричного резонатора та наведено результати експерементальних досліджень. При досліджені тонких діелектричних плівок виникають труднощі, тому що методи не забезпечують достатньої точності. При дослідженні метода тонких плівок результати показали, що при зменшенні товщини базового резонатора, збільшується точність. Тому метою роботи є адаптація методу складеного діелектричного резонатора для вимірювання параметрів тонких плівок. Для досягнення поставленої мети необхідно було вирішити наступні задачі: 1. Проаналізувати існуючи методи вимірюваняя НВЧ – параметрів діелектричних матеріалів. 2. Проаналізувати властивості тонкого діелектричного резонатора (ТДР). 3. Запропонувати метод дослідження параметрів тонких плівок на основі ТДР. 4. Експерементально перевірити метод тонких плівок на основі ТДР. Предметом і об’єктом даної робот є: Об’єкт: тонкий діелектричний резонатор Предмет: електродинамічні властивості тонкого діелектриного резонатора Наукова новизна: Теоретичне та експериментальне дослідження електро-динамічних властивостей ТДР показує, що на основі ТДР можна з достатньою точністю вимірювати НВЧ – властивості тонких діелектричних плівок.
In the given work, the nutritional pockets of the teoretical publications are stored in those thin dielectric resonators and the method of determining the NVH parameters in the power electronics. The method of a thin dielectric resonator is applied to the result of the experimental data. When study slim dielectric films arise difficulties, to that method do not gave accuracy. When the method of thin plots is used, the results have been shown, when the basic resonator is changed, the accuracy is determined. To the method of robotics is adaptation to the method of the stored dielectric resonator for the parameterization of thin cells. For achivment it's delivered goal it was necessary to solve the problem: 1. Analyze existing methods 2. Analyze power of a thin dielectric resonator (TDR). 3.Propose method of study parameters in the small films on the basis of the TDR. 4. Experimentally check method of thin plvok on the basis of the TDR. The subject і objective of this work is: Ob'ekt: thin dielectric resonator Subject: Electrodynamic power of a thin dielectric resonator Science novelty: Theoretically, this experiment is complementary to the electric-dynamical authorities of the TDR, but on the basis of the TDR, it is possible to obtain the accuracy of the NVCH - the power of subtle electrical add-ons.

Hafnium and Zirconium based gate dielectrics are considered potential candidates to replace SiO2 or SiON as the gate dielectric in CMOS processing. Furthermore, the addition of nitrogen into this pseudo-binary alloy has been shown to improve their thermal stability, electrical properties, and reduce dopant penetration. Because CMOS processing requires high temperature anneals (up to 1050 °C), it is important to understand the diffusion properties of any metal associated with the gate dielectric in silicon at these temperatures. In addition, dopant penetration from the doped polysilicon gate into the Si channel at these temperatures must also be studied. Impurity outdiffusion (Hf, Zr) from the dielectric, or dopant (B, As, P) penetration through the dielectric into the channel region would likely result in deleterious effects upon the carrier mobility. In this dissertation extensive thermal stability studies of alternate gate dielectric candidates ZrSixOy and HfSixOy are presented. Dopant penetration studies from doped-polysilicon through HfSixOy and HfSixOyNz are also presented. Rutherford backscattering spectroscopy (RBS), heavy ion RBS (HI-RBS), x-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), and time of flight and dynamic secondary ion mass spectroscopy (ToF-SIMS, D-SIMS) methods were used to characterize these materials. The dopant diffusivity is calculated by modeling of the dopant profiles in the Si substrate. In this disseration is reported that Hf silicate films are more stable than Zr silicate films, from the metal interdiffusion point of view. On the other hand, dopant (B, As, and P) penetration is observed for HfSixOy films. However, the addition of nitrogen to the Hf - Si - O systems improves the dopant penetration properties of the resulting HfSixOyNz films.

A reflectometria no domínio do tempo permite estimar o teor de umidade de um meio através da sua correlação com a constante dielétrica. Uma sonda helicoidal TDR, que pode ser cravada em conjunto outros ensaios de penetração in situ para a estimativa do teor de umidade em diversas profundidades, tem aplicação interessante para a investigação geotécnica do subsolo. No presente trabalho, uma sonda TDR foi adaptada e utilizada em conjunto ao ensaio CPT para caracterização de um perfil de solo arenoso não saturado que ocorre na região de Bauru (SP). A calibração dessa sonda foi feita em laboratório especificamente para esse solo. As equações de calibração que mostraram os melhores resultados foram definidas correlacionando a constante dielétrica, condutividade elétrica aparente e a massa específica seca com o teor de umidade. Com o intuito de melhorar a acurácia na determinação do teor de umidade em campo e eliminar possíveis interferências no registro da onda eletromagnética, foram efetuadas modificações em algumas características do projeto original dessa sonda. Tais modificações consistiram em separar os eletrodos condutores e as partes metálicas da sonda, e eliminar o cabo coaxial de extensão, conectando a sonda diretamente a um cabo coaxial de 12 m de comprimento. Tais mudanças levaram a uma melhoria significativa na determinação do perfil de teor de umidade do local estudado. Os valores de teor de umidade de campo determinados usando o TDR ao longo de 8 m de profundidade foram comparados com os valores de referência obtidos de amostras deformadas retiradas com trado mecânico. O erro médio na estimativa do perfil de teor de umidade gravimétrico utilizando a sonda TDR helicoidal foi de 1.61%, na última campanha de ensaios realizados. Os resultados dessa pesquisa indicam que esta ferramenta é adequada para estimar do perfil de teor de umidade para uso em conjunto com o ensaio CPT.
The time domain reflectometry allows estimating the moisture content of a medium by means of its correlation with the dielectric constant. A coil TDR probe, which can be driven into the ground together with others in situ penetration tests, can be used to estimate the moisture content at different depths. It is an interesting approach for geotechnical site characterization. In this work, a coil TDR probe was adapted and used in combination with the CPT test for the site characterization of an unsaturated sandy soil profile which occurs in the region of Bauru (SP). The probe calibration was performed in laboratory specifically for that soil. The calibration equation, which presented the best results, were defined correlating the dielectric constant, electrical conductivity and dry density with the moisture content. In order to improve the accuracy for determining the water content in the field and to eliminate possible interference on the electromagnetic wave registration, modifications were made in some characteristics of the original design of this probe. Such modifications consisted in separating the conductive electrodes from the metal parts of the probe, and eliminating the coaxial extension cable, connecting the probe directly to a coaxial cable 12 m long. Such changes have led to a significant improvement in the determination of the moisture content profile of the studied site. The moisture content values determined in situ by using the TDR along 8 m depth were compared with reference values obtained from disturbed soil samples collected using mechanical augers. The root mean square error of the gravimetric water content profile using the TDR coil probe was 1.61% in the last test campaign. The results of this research indicate that this tool is suitable to estimate the gravimetric moisture content together with the CPT test.

Ground penetrating radar (GPR) technology has existed for many decades, but it has only been in the last 20 to 30 years that it has undergone great development for use in near surface ground investigations. The early 1980's saw the first major developments in the application of GPR for pavements (i.e. engineered structures designed to carry traffic loads), and it is now an established investigation technique, with generic information included in several national standard guidance documents. Analysis of GPR data can provide information on layer depths, material condition, moisture, voiding, reinforcement and location of other features. Assessing the condition of pavements, in order to plan subsequent maintenance, is essential to allow the efficient long-term functioning of the structure and GPR has enhanced and improved the range and certainty of information that can be obtained from pavement investigations. Despite the recent establishment of the technique in pavement investigation, the current situation is one in which GPR is used routinely for pavement projects in only a minority of countries, and the specialist nature of the technique and the sometimes variable results that are obtained can mean that there is both a lack of appreciation and a lack of awareness of the potential information that GPR can provide. The fact that GPR is still a developing technique, and that many aspects of its use are specialised in their nature, means that there are also several technical aspects of GPR pavement investigations which have not been fully researched, and knowledge of the response of GPR to some material conditions has not been fully established. The overall aim of this EngD research project was to provide improved pavement investigation capabilities by enhancing the methodologies and procedures used to obtain information from GPR. Several discrete research topics were addressed through various research methods including a literature review, fieldwork investigations, experimental laboratory investigations and a review of previously collected data. The findings of the research allowed conclusions and recommendations to be made regarding improved fieldwork methodologies, enhancing information and determining material condition from previously collected GPR data, assessing the effect of pavement temperature and moisture condition on GPR data and also on managing errors and uncertainty in GPR data. During the EngD project, a number of documents and presentations have been made to publicise the findings both within the EngD sponsoring company (Jacobs) and externally, and an in-house GPR capability has been established within Jacobs as a direct result of the EngD project.

Ground penetrating radar (GPR) technology has been used for the past 20 years for a variety of applications to assess transportation infrastructure. However, the main issue after all these years remains: "How well does GPR work and under what conditions?" Results show that GPR works well for some situations, but is not an appropriate tool for other situations. It is not used currently on a routine basis by the US Departments of Transportation (DOTs) due mainly to difficulties encountered with data interpretation. Data interpretation difficulties are mainly attributed to the fact that images obtained from the reflected signals are not photographs of the features that are beneath the surface being investigated. The images show the amplitude of the radar-reflected signals from the interfaces with different dielectric properties. Therefore, a considerable amount of experience and operator skill may be required to correctly interpret sub-surface radar results. To better understand reflected GPR signals, this research was conducted with the following objectives: to determine the dielectric properties of concrete over the used GPR frequency range; to synthesize the reflected air-coupled radar signals and compare them with measured waveforms; to model and study the effects of simulated defects in concrete on the reflected air-coupled and ground-coupled radar signals; and to validate the research results in the field by predicting layer thicknesses of flexible pavements and detecting moisture in flexible pavement systems. Several concrete slabs, 1.5x1.5 m, were constructed with known thicknesses, simulated defects, and different reinforcement configurations. The concrete mixes included four different bridge deck mixes and one concrete pavement mix used in the State of Virginia. Results have shown that the dielectric constant of concrete is frequency and mix dependent. However, modeling the reflected signals using an average complex dielectric constant over the entire radar frequency range led to modeled waveforms comparable to the measured waveforms. Although air- and water-filled voids did distort the reflected waveforms, a model was developed to predict the reflected waveforms from the simulated defects. Reinforcement was found to affect the reflected waveforms only when it was oriented in a direction perpendicular to the GPR antennas. A model was also developed to predict the GPR waveforms obtained from flexible pavements. This model could be used in a procedure to measure layer thicknesses more accurately by including losses that occur inside the pavement materials. Two different case studies, where a ground-coupled GPR system was used to locate moisture at different layers, have led to the conclusion that the ground-coupled GPR is a feasible tool to detect moisture inside pavements.
Ph. D.

Робота виконана на кафедрі технології та обладнання зварювального виробництва Тернопільського національного технічного університету імені Івана Пулюя Міністерства освіти і науки України.Захист відбувся в 2015 р. на засіданні спеціалізованої вченої ради Д58.052.01 у Тернопільському національному технічному університеті імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56, навчальний корпус №2, аудиторія №79. З дисертацією можна ознайомитися у науково-технічній бібліотеці Тернопільського національного технічного університету імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56.
Дисертаційна робота присвячена розв’язанню наукової проблеми – підвищення ефективності та функціональних можливостей експериментальних досліджень шляхом розробки експериментально-розрахункових оптичних методів визначення напружено-деформованого та граничного стану прозорих діелектриків на основі аналізу параметрів тензора діелектричної проникності. Теоретично обґрунтовано та експериментально підтверджено новий метод визначення НДС, який використовує п’єзооптичний ефект поглинаючого середовища (метод поглинання – МП), одержано формули визначення КІН за даними МП. Теоретично обґрунтовано та експериментально підтверджено новий метод визначення НДС, який базується на ефекті дифузного поверхневого розсіювання (МДПР), одержано формули визначення КІН (моментів) за допомогою даного методу, а також сумісним вимірюванням даних МДПР та фотопружності. Розроблено та реалізовано модель оптичного тензодатчика, який працює на основі МДПР, обґрунтовано застосування методу для оцінки «зони шийкоутворення» біля вершини тріщини. Розвинуто поляризаційно-оптичний метод для розв’язання таких задач експериментальної механіки руйнування, як визначення КІН КІ, КІІ, КІІІ, для неоднорідного основного напруженого стану та малих за величиною (до ) картин оптичної анізотропії, для випадків великих різниць оптичного ходу ( ) та значних градієнтів, коли важко визначити нульову ізохрому. Розроблено фізико-механічний критерій граничного стану діелектриків (критерій тензора діелектричної проникності - ТДП), експериментально досліджено, згідно критерію ТДП, граничний стан пластин з оргскла та оболонок з епоксидної смоли з тріщинами. За допомогою модифікованих методик поляризаційно-оптичного методу та розробленого фізико-механічного критерію ТДП проведено комплексне дослідження напруженого та граничного станів багатошарових структур (триплексів) при температурі Т=213 К і при можливій наявності тріщиноподібних дефектів у їх складових частинах (елементах).
Диссертационная работа посвящена решению научной проблемы –повышению эффективности и функциональных возможностей экспериментальных исследований путем разработки экспериментально-расчетных оптических методов определения напряженно-деформированного и предельного состояния прозрачных диэлектриков на основе анализа параметров тензора диэлектрической проницаемости. Теоретически обоснован и экспериментально подтвержден метод определения НДС, который использует пьезооптический эффект поглощающей среды (метод поглощения - МП), действие которого основано на анализе величин изменения мнимой части компонент тензора диэлектрической проницаемости (ТДП) при нагружении объекта. Метод предоставляет принципиальную возможность определения НДС объектов, изготовленных из непрозрачных в видимом диапазоне диэлектриков и позволяет определять сразу отдельно квазиглавные напряжения и деформации, а не их линейные комбинации, как в поляризационно-оптических (разности) и когерентно-оптических (суммы) методах. Предложенный метод поглощения применен для определения величин КИН при исследовании объектов, содержащих трещиноподобные дефекты (получены формулы определения КИН по данным МП). Теоретически обоснован и экспериментально подтвержден метод определения НДС, который использует эффект диффузного поверхностного рассеивания (метод диффузного поверхностного рассеивания – МДПР). Предложенный метод основывается на измерениях перераспределения интенсивностей зеркальной и диффузных составляющих рассеянного поверхностью объекта светового потока при локальном изменении ее кривизны. Метод позволяет проводить измерения в широком диапазоне изменения величин деформаций: от порогового значения чувствительности до разрушения объектов (10-2 – для полимеров, 10-0- для эластомеров), значительно превышая диапазон измерения спекл-интерферометрии. Получены формулы определения КИН (моментов) по данным МДПР для симметричного относительно берегов трещины моментного состояния (определения К3) и несимметричного моментного состояния (определения К3 и К4). Разработаны и реализованы модели оптических датчиков деформаций, которые работают на эффекте диффузного поверхностного рассеивания (датчики МДПР). Чувствительным элементом датчика первого конструктивного исполнения является изогнутая пластинка, а второго – выемка с диффузнорассеивающей поверхностью. Датчик МДПР, чувствительным элементом которого является выемка, не крепится определенным образом на поверхности объекта, а является частью приповерхностного слоя. Такая конструкция позволяет повысить точность измерений за счет отсутствия погрешностей в системе “датчик–склеивающий слой–поверхность объекта”. Предложен физико-механический критерий предельного состояния диэлектриков (критерий тензора диэлектрической проницаемости – ТДП). Критерий основывается на изменении компонент тензора диэлектрической проницаемости при нагружении объекта и позволяет интегрально учитывать влияние как механических, так и физических факторов (температуры, влажности, радиации) на предельное состояние диэлектриков. В данном критерии при изменении физических факторов изменяется не только предел прочности (как в классических механических теориях), а и выражение для эквивалентного напряжения за счет изменения величины соотношения оптико-механических констант С1/С2. Предложенный критерий ТДП позволяет определять долговременную прочность полимеров при постоянной нагрузке. Модифицирован поляризационно-оптический метод исследования натурных объектов с трещинами для малых по величине (до 1λ, где λ – длина волны зондирующего излучения) картин оптической анизотропии и для случаев больших разностей оптического хода (>8 λ) и значительных градиентов, при которых сложно определить нулевую изохрому. Исследована кинетика разрушения и предельное состояние неорганического силикатного стекла (как составной части гомогенных и гетерогенных триплексов). Проанализированы, при помощи критерия ТДП, данные разрушения пластин из органического стекла (как составной части гетерогенных триплексов) с краевыми трещинами. На моделях из эпоксидных смол ЭПСА и ЭД-20М показано конструкционное и технологическое влияние обрамления на распределение величин КИН при прорастании поверхностных трещин (надрезов) в сквозные в склеивающем слое триплексов. С помощью модифицированных методик поляризационно-оптического метода и разработанного физико-механического критерия ТДП проведено комплексное исследование напряженного и предельного состояния гомогенных и гетерогенных триплексов при сниженных температурах (до Т=213 К), с обрамлением и без, при возможном наличии трещиноподобных дефектов в их составных частях (элементах): неорганическом силикатном стекле, органическом стекле и склеивающем слое. Это позволило определить влияние гетерогенности и обрамления, а также получить численные результаты оценки НДС и предельного состояния для различных вариантов триплексов и выбрать оптимальный: гетерогенный триплекс без обрамления.
Thesis is dedicated to the solution of a scientific problem – developing of the optical experimental and computational methods for determining the stress-strain and limit states of transparent dielectrics on the basis of the analysis of the dielectric penetration tensor. The author theoretically justified and experimentally confirmed the new method for determining the SDS, that uses the piezooptic effect of absorbing environment (the absorption method – AM), obtained the formulae for finding SIF accord Кing to the data of the AM. The author theoretically justified and experimentally confirmed a new method for determining the SDS on the basis of the method of diffuse surface scattering (MDSS), obtained the formulae for finding SIF with help of this method and due to the joint estimation of data of the MDSS and photo resilience as well. The author developed and realized the model of optical strain gauge that works on the basis of the MDSS, the application of the method for estimation of “neck-like formation area” at the crack tip. The author developed the polarized and optical method for solution of such tasks of experimental mechanics of destruction like SIF F1 F2 F3 in the case of finding heterogeneous stress state and the small size (<1λ) pictures of optical anisotropy in the case of significant optical motion’s differences (>8λ) and significant gradients when it is difficult to determine the zero isochromat. The author developed the physical-mechanical criterion of boundary state of dielectrics (the criterion of dielectric penetration tensor (DPT)) and experimentally investigated according to the criterion of DPT the boundary state of the organic glass plates and epoxy resin’s casing with cracks. Due to the modified polarized and optical method and developed physical-mechanical criterion of DPT was conducted the complex study of stress and boundary states of multilayer structures (triplexes) with the temperature T= 213 K and with the possible availability of crack-like defects in their component parts (elements).

Thesis (MScEng)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: An antenna for ground level deployed Ground Penetrating Radar applications is presented. The antenna is matched to the ground via a low impedance dielectric matching section improving the radiation pattern and input impedance characteristics. A bowtie antenna was used for the design with the edges rounded to stabilize the resonant frequency. The radiation pattern was focused to the one side of the antenna for ground penetration using a non-absorptive metallic cylindrical air filled cavity. Edge reflections from the antenna were reduced by means of discrete resistor terminations between the antenna and the cavity. A wire equivalent of the solid metallic antenna was investigated giving similar characteristics to that of the solid antenna. The radiation pattern deformation arising from transmitting a wave from an antenna in air into the ground due to the impedance mismatch was investigated. This was overcome with the use of a polypropylene dielectric slab inserted between the antenna and the ground. Together with improving the radiation pattern the antenna was less sensitive to ground parameter variations and to an air gap introduced between the slab and the ground. This was implemented as a wheel mounted system with adjustable height settings depending on the terrain. A pair of mounted antennas was constructed to be tested on an existing bistatic Stepped Frequency Continuous Wave radar operating in the 50-400 MHz band developed by the University of Cape Town. This antenna is seen as providing a solution to the problem of coupling an antenna to a low wave impedance medium such as ground.
AFRIKAANSE OPSOMMING: 'n Antenne word vir Grond Penetrerende Radar toepassings voorgestel. Dit is spesifiek ontwikkel vir oppervlak ontplooide stelsels ontwerp. Die antenne is aangepas tot die grond deur middel van 'n diëlektriese aanpassingseksie wat die starlingspatroon en intree-impedansie karakteristieke verbeter. Die antenne is tot die grond toe aangepas deur middel van 'n diëlektriese aanpassingseksie wat die starlingspatroon en intree-impedansie karakteristieke verbeter. 'n Strikdas antenne was gebruik vir die ontwerp, met die kante gerond om die resonante freqwensie te stabiliseer. Om die stralingspatroon van die antenne na een kant toe te fokus was 'n nie-absorbeerede metaleiese, luggevulde, silindriese holte daaragter geplaas om die energie vorentoe te weerkaats. Weerkaatsings van die rand van die antenne word onderdruk met behulp van koppelende weerstande tussen die antenne en die holte. A draad ekwivalent van die antenne was ook ondersoek met goeie ooreenstemming met die soliede strikdas. Die impedansie wanaanpassing wat ontstaan as 'n antenne wat in lug is, in die grond in straal veroorsaak dat die stralingspatroon van die antenne vervorm word. Dit was gevind dat deur 'n aanpassings blad van 'n diëlektriese materiaal, naamlik polipropileen, gebruik te maak tussen die antenne en die grond dat dit die probleem oplos. Saam met dit was gevind dat die antenne minder sensitief was vir veranderings in grondparameters en ook vir 'n lug gaping tussen die blad en die grond. Die het gemaak dat die antenne op wiele gemonteer kon word met verstelbare hoogte afhangend van die terrein. 'n Stel geskaleerde antennes was gemaak om op 'n beskikbare bistatiese Trap Frekwensie Kontinue Golf radar te werk. Dit werk oor die 50-400 MHz band en was ontwikkel deur die Universitiet van Kaapstad. Die antenne word gesien as 'n oplossing vir antenne koppelingsprobleme ondervind by laë golf impedansie materiale.

Um der Mikrowellenerwärmung als Single- oder Hybridanwendung im industriellen Ofenbau ein weiteres Anwendungsspektrum zu eröffnen, wird dem Anlagenkonstrukteur im Rahmen dieser Arbeit eine Aufstellung von Entwicklungsprioritäten und Konstruktionshinweisen übergeben. Für eine energieeffiziente Ausnutzung des technologischen Potenzials wird hierbei nicht - wie in der Vergangenheit - die Feldstärkenverteilung, sondern das Reflexionsverhalten in den Vordergrund gestellt. Durch die Entwicklung und den Aufbau eines Messplatzes zur Bestimmung temperaturspezifischer Dielektrizitätsparameter konnte die Realitätsnähe der Simulation für die anwendungsorientierte Applikatorentwicklung gesteigert werden. Die Anwendbarkeit der Auslegungskriterien wird im Rahmen der Projektierung und des Aufbaus einer Beispielanlage zur Entbinderung von keramischen Grünkörpern und bei der Entwicklung zahlreicher mikrowellenspezifischer Anlagenbauteile verifiziert.

According to a 1999 Federal Highway Administration statistic, the U.S. has around 8.2 million lane-miles of roadways that need to be maintained and rehabilitated periodically. Therefore, in order to reduce rehabilitation costs, pavement engineers need to optimize the rehabilitation procedure, which is achieved by accurately knowing the existing pavement layer thicknesses and localization of subsurface defects. Currently, the majority of departments of transportation (DOTs) rely on coring as a means to estimate pavement thicknesses, instead of using other nondestructive techniques, such as Ground Penetrating Radar (GPR). The use of GPR as a nondestructive pavement assessment tool is limited mainly due to the difficulty of GPR data interpretation, which requires experienced operators. Therefore, GPR results are usually subjective and inaccurate. Moreover, GPR data interpretation is very time-consuming because of the huge amount of data collected during a survey and the lack of reliable GPR data-interpretation software. This research effort attempts to overcome these problems by developing new GPR data analysis techniques that allow thickness estimation and subsurface defect detection from GPR data without operator intervention. The data analysis techniques are based on an accurate modeling of the propagation of the GPR electromagnetic waves through the pavement dielectric materials while traveling from the GPR transmitter to the receiver. Image-processing techniques are also applied to detect layer boundaries and subsurface defects. The developed data analysis techniques were validated utilizing data collected from an experimental pavement system: the Virginia Smart Road. The layer thickness error achieved by the developed system was around 3%. The conditions needed to achieve reliable and accurate results from GPR testing were also established.
Ph. D.

Abstract This PhD thesis is composed of a synopsis and five published papers that are focused on both the research results of studies on electrical properties of road materials and subgrade soils and their seasonal changes and the use of Ground Penetrating Radar technique in traffic infrastructure surveys. The data for this survey was collected mainly in Finland, Texas, Scotland and Sweden and thus presents many kinds of road materials, subgrade soils and climate conditions. The synopsis of this work begins with a presentation of the theory and basic principles of GPR techniques. Special attention is given to the dielectric properties and seasonal changes of unbound road materials and subgrade soils. The synopsis also presents different kinds of GPR hardware systems as well as recommendations and experiences from different data collection, processing and interpretation techniques. Special attention is given to a method whereby GPR data is integrated with other road survey data and then analysed using a number of structural diagnostic methods. Finally, the synopsis provides an overview of of the various GPR applications on roads and streets, bridges, railways and airports. The laboratory test results presented in this work show that the relationship between dielectric value and increasing water content is not linear or exponential but more likely a series of logarithmic functions. Laboratory results also showed that dielectric dispersion, which can be related to poorly performing subgrade soils and road aggregates, takes place mainly in loosely bound adsorption water and capillary water layer. As such these moisture sensitive problem materials can also be identified during the dry summer seasons when they are stiff. Dielectric value and electrical conductivity can also be related to other technical properties of road materials and subgrade soils such as frost susceptibility, shear strength, plastic limit, compaction degree and voids content. Laboratory tests and field data collected using the Percostation technique also demonstrate that a knowledge of seasonal changes and thermodynamics is very important in understanding and modelling the mechanical behaviour of road structures. Finally, laboratory and field tests indicate that colloids have an important role in the failure mechanism of the road materials. This research demonstrates that the GPR technique not only gives valuable structural information on the different types of structures and subgrade soils but it provides a wide range of information of the electrical properties of the materials under survey which can be further related to their mechanical performance. The best information will be gained if GPR data is analysed together with other non destructive testing data collected form the roads, railways and airports.

Le contrôle des chaussées neuves en génie civil est primordial pour assurer sa bonne miseen oeuvre et lui conférer une durée de vie optimale. Dans cet objectif, divers paramètresphysiques nécessitent d'être scrupuleusement calibrés et contrôlés afin d'éviter une dégradation précoce de la chaussée et des problèmes de sécurité pour les conducteurs qui l'empruntent. De plus, les coûts associés à la mise en place et à la maintenance des chaussées sont considérables. Parmi les propriétés qui requièrent une attention particulière, la compacité, qui est indicative de la quantité d'air en volume dans la chaussée, est celle qui nous intéresse dans cette étude. Actuellement, seulement deux méthodes en laboratoire (en Europe) sont considérées comme des méthodes normalisées pour déterminer la compacité. Néanmoins, ces techniques sont destructives et/ou nucléaires ce qui est un frein majeur à leur utilisation. Durant ces deux dernières décennies, de nouvelles techniques électromagnétiques (non nucléaires et non destructives) ont émergé et ont prouvé leur forte utilité dans le domaine de la géophysique et du génie civil et plus particulièrement pour la détermination de la compacité. Cependant, ces nouvelles techniques nécessitent de prendre un certain nombre de précautions pour déterminer la compacité. Tout d'abord, elles permettent de mesurer la permittivité diélectrique du matériau en question. Ainsi pour déterminer la compacité, il est nécessaire d'utiliser des lois de mélange électromagnétiques. L'utilisation de ces modèles requiert une connaissance précise des constituants qui composent la chaussée ainsi que de leurs propriétés (masse volumique et permittivité diélectrique). La première partie de ce travail démontre la pertinence d'utiliser un radar à sauts de fréquences pour déterminer la compacité. L'étude de plusieurs lois de mélange électromagnétiques a été réalisée et les modèles présentant les meilleurs résultats ont été sélectionnés. Cependant, ces techniques font face de nos jours à un problème majeur. En effet, l'utilisation de matériaux recyclés est de plus en plus fréquente pour la construction de nouvelles chaussées ce qui rend la détermination de la compacité encore plus difficile par des méthodes électromagnétiques. Par conséquent, plusieurs méthodologies ont été développées, et sont proposées pour déterminer la compacité d'une nouvelle autoroute qui comporte des matériaux recyclés. La seconde partie de ces travaux de recherche porte sur la caractérisation diélectrique de plusieurs roches qui sont les éléments principaux d'une chaussée. Cette caractérisation est validée de basses à hautes fréquences mais aussi en fonction de la température. Les résultats montrent que à haute fréquence, la permittivité est principalement dépendante de la densité et de la composition chimique de la roche. En revanche, lorsque la fréquence d'investigation diminue et que la température varie, d'autres phénomènes apparaissent et changent dramatiquement le comportement diélectrique de la roche. Il a également été montré que l'eau joue un rôle majeur dans le comportement diélectrique à basse fréquence de la roche. Ces phénomènes se répercutent à "haute fréquence" par de très faibles variations qui pourraient expliquer les déviations obtenues par les méthodes électromagnétiques capacitives qui fonctionnent dans la région du MHz et qui sont également utilisées pour le contrôle de la compacité des chaussées neuves
The control of new paved road is primordial to ensure its quality as well as its lifetime. Thus, several physical properties need to be well calibrated and controlled in order to avoid early degradations and safety issues for the drivers. Furthermore, the coast associated to the road building and the road maintenance is significant which makes the implementation of asphalt pavement according to the standard even more important. Among the properties that need attentions, the compactness which is indicative of the air void concentration in the asphalt pavement is the one we are interested in. Currently, only two methods in laboratory (in Europe) are considered as standards to assess the compactness. Nevertheless, these techniques are either nuclear or destructive which is a major hindrance. In the past two decades, new electromagnetic (EM) techniques have emerged and proved their great utility for geophysics or civil engineering applications and more importantly for the compactness assessment. However, these non-destructive and non-nuclear methods require many special precautions for the compactness assessment. First of all, they allow to measure the dielectric permittivity of the investigated material. Then to figure out the compactness, the use of EM mixing models is required. This leads to the accurate knowledge of every components constituting the asphalt pavement and their related properties (density and permittivity). The first main part of this work spotlights the relevance of using a step frequency radar for the compactness assessment. The study of several EM mixing models is performed to select the most appropriate ones. Nowadays, one of the challenges to address for these techniques is that the use of recycled materials is more and more commonly implemented for new roads building. Indeed, as the knowledge of the component properties is required, this makes the compactness assessment even more difficult. As a consequence, several methods have been developed and are proposed to assess the compactness of a new paved highway containing recycled asphalt pavement. The second main part of this research is the dielectric characterization of many rocks which are the main component of the asphalt pavement. This characterization is validated from low to high frequencies and also as a function of the temperature. The results show at high frequency that the permittivity is mainly dependent on the density and the chemical composition of the rock. However, as the frequency decreases and the temperature varies, this is not longer true and additional phenomena appear and drastically change the dielectric behavior of the rock. Also, it has been shown that the water plays a major role on the dielectric behavior at low frequency. This phenomena are reflected partially by small variations at "high frequency" that could explained the deviations obtained for capacitive techniques which work in the MHz region and which are used also for the compactness assessment

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This paper aims to analyze the Ground Penetrating RADAR as tool in the determination of the thickness of the layers of the flexible road pavement of automatic way and the density of the asphalt layer supported by integrated testing of GPR and geotechnical data. The first experiment was conducted at the Presidente Dutra highway (BR116), Pirai - RJ, while the data for the second experiment were obtained from the BR040 highway, Sete Lagoas - MG. In order to achieve the objectives of this study, two methodologies were developed: the first one, directed to the identification of the thicknesses of the layers of flexible pavements of automated way; the second one, focused on determining the density of the layer of asphalt surfaces. The first methodology showed promising results, once it presented good classification results for the classes 1 (off-set) and 3 (macadam), however, was confusion between the "blocks" classified for the classes 2 (asphalt) and 4 (subgrade). A possible alternative, for improvement, would be: to use other texture extractor of the wavelet transform family; to use another type of interpolation, using a that better represents the trends of the coefficients to be generated the surface; to increase the number of training and testing samples, or even to use another type of classifier, such as Artificial Neural Networks. However, this is a field that is worth being investigated more deeply, since the results proved to be significant. The second methodology, regarding the correlation of the density of the asphalt layer through the dielectric value, measured by means an ground coupled antenna, of 1,6GHz, using the technique of the reflection, it presented satisfactory values in spite of the few sampling points, showing to be a good alternative to determine indirectly the density of the asphalt layer and for future works in the area.
Este trabalho tem o propósito de analisar o desempenho do RADAR de penetração no solo como ferramenta na determinação das espessuras das camadas do pavimento rodoviário flexível de maneira automática e a densidade da camada de revestimento apoiado em testes integrados de GPR e dados geotécnicos. O primeiro experimento foi realizado na rodovia Presidente Dutra (BR116), município de Piraí - RJ, em quanto os dados para o segundo experimento foram obtidos na rodovia BR040, município de Sete Lagoas - MG. Para atingir os objetivos do trabalho foram elaboradas duas metodologias: a primeira delas, direcionada à identificação das espessuras das camadas de pavimentos flexíveis de modo automatizado; a segunda, voltada para a determinação da densidade da camada de revestimento asfáltico. A primeira metodologia apresentou, de uma maneira geral, resultados promissores, uma vez que foram bons os resultados de classificação para as classes 1 (off-set) e 3 (macadame), no entanto, houve confusão entre os “blocos” classificados para as classes 2 (revestimento) e 4 (subleito). Uma possível alternativa para a melhoria dos resultados seria mudar o extrator de textura utilizado (transformada wavelet), valeria apena testar outros extratores da família wavelet; outra opção seria utilizar outro tipo de interpolador, usando um que pegue mais as tendências dos coeficientes ao se gerar a superfície; também seria interessante aumentar o número de amostras de treinamento e teste, ou até mesmo, utilizar outro tipo de classificador, como por exemplo, Redes Neurais Artificiais. Todavia, esse é um campo que vale ser pesquisado mais profundamente, uma vez que os resultados alcançados se mostraram esperançosos. A segunda metodologia, referente à correlação da densidade da camada de revestimento através do valor dielétrico, medido por meio de uma antena de contato no solo, de 1,6 GHz, utilizando a técnica da reflexão, apresentou valores satisfatórios apesar dos poucos pontos amostrados, mostrando ser uma boa escolha para se determinar a densidade da camada de revestimento de maneira indireta e para trabalhos futuros na área.

Um der Mikrowellenerwärmung als Single- oder Hybridanwendung im industriellen Ofenbau ein weiteres Anwendungsspektrum zu eröffnen, wird dem Anlagenkonstrukteur im Rahmen dieser Arbeit eine Aufstellung von Entwicklungsprioritäten und Konstruktionshinweisen übergeben. Für eine energieeffiziente Ausnutzung des technologischen Potenzials wird hierbei nicht - wie in der Vergangenheit - die Feldstärkenverteilung, sondern das Reflexionsverhalten in den Vordergrund gestellt. Durch die Entwicklung und den Aufbau eines Messplatzes zur Bestimmung temperaturspezifischer Dielektrizitätsparameter konnte die Realitätsnähe der Simulation für die anwendungsorientierte Applikatorentwicklung gesteigert werden. Die Anwendbarkeit der Auslegungskriterien wird im Rahmen der Projektierung und des Aufbaus einer Beispielanlage zur Entbinderung von keramischen Grünkörpern und bei der Entwicklung zahlreicher mikrowellenspezifischer Anlagenbauteile verifiziert.