• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 116
  • 54
  • 36
  • 16
  • 14
  • 6
  • 3
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 326
  • 81
  • 54
  • 52
  • 41
  • 38
  • 38
  • 34
  • 34
  • 34
  • 27
  • 27
  • 24
  • 23
  • 23
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

[en] PERFORMANCE ANALYSIS OF AN OPTICAL MANHATTAN STREET NETWORK WITH DEFLECTION ROUTING / [pt] ANÁLISE DO DESEMPENHO DE REDES ÓPTICAS DE TOPOLOGIA MANHATTAN STREET COM ROTEAMENTO POR DEFLEXÃO DE PACOTES

BRUNO CARNEIRO LEAO GUEDES 19 July 2005 (has links)
[pt] Redes Manhattan Street (MS) têm sido descritas como um arranjo linear bidimensional de nós, semelhante à configuração de ruas e avenidas de Manhattan. O roteamento por deflexão é implementado encaminhando os pacotes que atingem um determinado nó a uma de suas saídas de forma síncrona ou assíncrona. O principal objetivo deste trabalho consiste na simulação e análise de redes totalmente ópticas configuradas segundo a topologia MS. O roteamento por deflexão e o assincronismo são considerados, para evitar complexidade eletrônica e armazenamento de pacotes no domínio óptico. Serão apresentadas as características das redes MS, suas propriedades estruturais e os parâmetros utilizados para analisar seu desempenho. Uma metodologia analítica dedicada a obtenção teórica destes parâmetros será introduzida. Serão apresentados alguns conceitos básicos sobre simulação de redes;diversas simulações da rede proposta utilizando os protocolos UDP e TCP; uma descrição do software que foi utilizado para realizar as simulações; uma comparação entre os resultados obtidos através da simulação e os obtidos através da metodologia analítica; e uma análise do efeito da latência na vazão do protocolo TCP. / [en] Manhattan Street (MS) Networks are bidimensional linear node sets arranged as the avenues and streets of Manhattan. The simulation and analysis of all-optical MS networks is the central target of this paper. In order to avoid using complex electronics and/or optical domain buffers, the deflection routing and the asynchronism are taken into account in the analysis. Deflection routing is performed by conveying incoming packets towards one of the two outputs. The characteristics of MS Networks are presented, along with their structural properties and the parameters used for performance analysis. An analytical methodology for the theoretical obtaining of these parameters is described. Some basic concepts on network simulation are discussed. Several simulations of the proposed network are presented, using both UDP and TCP protocols, and the software used for simulations is also described. The obtained results are compared and discussed with respect to the previously described analytic methodologies. Finally, the effect of network latency on the TCP-protocol throughput is assessed.
202

Estudo da fluência em vigas de concreto reforçado com fibras de aço, com aplicação de conceitos da mecânica da fratura / Creep analysis of steel fiber reinforced concrete based on beam tests and fracture mechanics concepts

Miller, Karla Peitl 28 July 2008 (has links)
Embora sejam reconhecidas diversas vantagens na adição de fibras curtas de aço ao concreto (CRFA), em especial o ganho de tenacidade, pouco se sabe a respeito da fluência desses materiais compostos. Este trabalho teve como objetivo principal investigar o potencial e as dificuldades inerentes de um método de avaliação experimental da fluência pelo ensaio de vigas, como possível alternativa aos ensaios de compressão axial já consagrados. Ao mesmo tempo, considerando a nova tendência de exploração de compósitos híbridos - formados por fibras de diferentes características, de modo a obter respostas adequadas aos processos de micro e macrofissuração - tomou-se como objeto de estudo experimental um conjunto de modelos e corpos-de-prova de CRFA comum e de CRFA híbrido, este formado pela combinação de fibras de aço de diferentes comprimentos, umas mais longas e outras mais curtas. Para caracterização dos materiais, foram efetuados ensaios para determinação das principais propriedades mecânicas de interesse em distintas idades. As proporções da mistura adotada neste programa experimental foram baseadas em dados de estudos anteriores, que suscitaram investigações mais detalhadas. Entretanto, neste particular programa de ensaios, a adição das fibras, principalmente as mais curtas, acarretou maior teor de ar incorporado ao compósito, o que penalizou o seu desempenho em alguns aspectos. Os resultados desses ensaios demonstraram pouca influência das fibras sobre as propriedades de resistência à compressão, módulo de elasticidade e resistência à tração por compressão diametral. Quanto à fluência, o desempenho do CRFA e do compósito híbrido foi inferior ao da matriz. Por outro lado, notou-se maior restrição à retração do concreto com a adição de fibras. Na análise dos resultados experimentais, o estudo das flechas diferidas foi efetuado pelas correspondentes deformações, para interpretação do fenômeno por meio das curvas de fluência específica. O ajuste de resultados experimentais para curvas de fluência específica demonstrou que a fluência em vigas, apesar de apresentar - comparativamente aos modelos teóricos fundamentados em ensaios de compressão - maior taxa inicial, maiores coeficientes de fluência e estabilização aparentemente mais rápida, pode ser representada por modelos teóricos semelhantes aos usuais. As curvas de tendência determinadas para a matriz foram comparadas com aquelas derivadas de expressões dadas por normas técnicas (NBR 6118:2003 e ACI209:1982), assim como com as obtidas em simulações numéricas efetuadas como software DIANA®. A fluência também foi avaliada experimentalmente em vigas entalhadas, submetidas apenas à ação do peso-próprio, sendo estes ensaios também simulados por meio de modelagem numérica e aplicação de conceitos da mecânica da fratura. Os resultados analisados permitem dizer que há possibilidade de avaliar a fluência pela metodologia estudada, o que oferece um método alternativo para avaliação experimental da fluência. Nesta pesquisa, avaliou-se também a alteração de rigidez das vigas ensaiadas em decorrência dos efeitos do tempo, por meio de ensaios dinâmicos de vibração livre, segundo a ASTM C-215:1991a. / Despite of the well known advantages of steel fiber addition to concrete (SFRC), especially the toughness improvement, only a few number of studies has been developed about creep on these composites. The main purpose of this research is to investigate the feasibility and inherent difficulties related to a particular creep evaluation method. This method is based on beam test results and their analysis by fracture mechanics theory. It is intended to become an alternative method instead of the usual creep analysis of axial compression test results. At the same time, looking at the development of hybrid composites - made of distinct kind of fibers to obtain the best responses for micro and macrocracking - an experimental program was performed. Specimens molded with plain concrete, ordinary SFRC and hybrid SFRC were tested in flexure, the last one made of an association of short and large steel fibers. Characterization tests were performed to obtain the main mechanical properties of these materials at several ages. The mixture proportions were based in previous studies, where good performance characteristics were observed in hybrid composites. Nevertheless, in this particular test series, the addition of shorter steel fibers resulted in high air contents, what probably caused the decrease of the composite\'s performance in some aspects. The test results displayed low influence of the fiber addition on mechanical properties such compression strength, modulus of elasticity and tensile strength. Creep performance showed to be worse in the SFRC and hybrid composites than in plain concrete matrix. However, the reinforcement with steel fibers improved the shrinkage restrain. The analysis of the long-term beam deflections was made by finding the corresponding strains in the sections. Afterwards, specific creep functions were obtained by regression methods. The experimental creep functions were compared to the existing ones in literature and design codes. Despite of some differences, such as higher initial creep rate, higher creep coefficients and faster stabilization, it may be concluded that these functions represented quite well the phenomenon. Also experimental functions for plain concrete showed good results when compared to creep prediction model given by design codes, such as the Brazilian NBR 6118:2003 and ACI 209:1982. Comparison with numerical modeling results also gave satisfactory results. Creep in flexure was also evaluated by means of notched beam tests, where the sustained load was performed only by the beam self-weight. The test results were analyzed by numerical modeling and application of fracture mechanic concepts. The overall results showed the feasibility of creep assessing by the beam test method, which can be, after further detailed test series, a good alternative method instead of axial compression tests. Also dynamic free vibration tests were performed, according to ASTM C-215:1991 recommendations, to investigate the beam stiffness loss due to long term loading effects. These tests showed that modal analysis can be a helpful method in the tests, since it does not introduce damages in the test specimens.
203

Chemical modifications and passivation approaches in metal halide perovskite solar cells

Abdi Jalebi, Mojtaba January 2018 (has links)
This dissertation describes our study on different physical properties of passivated and chemically modified hybrid metal halide perovskite materials and development of highly efficient charge transport layers for perovskite solar cells. We first developed an efficient electron transport layer via modification of titanium dioxide nanostructure followed by a unique chemical treatment in order to have clean interface with fast electron injection form the absorber layer in the perovskite solar cells. We then explored monovalent cation doping of lead halide perovskites using sodium, copper and silver with similar ionic radii to lead to enhance structural and optoelectronic properties leading to higher photovoltaic performance of the resulting perovskite solar cells. We also performed thorough experimental characterizations together with modeling to further understand the chemical distribution and local structure of perovskite films upon monovalent cation doping. Then, we demonstrate a novel passivation approach in alloyed perovskite films to inhibit the ion segregation and parasitic non-radiative losses, which are key barriers against the continuous bandgap tunability and potential for high-performance of metal halide perovskites in device applications, by decorating the surfaces and grain boundaries with potassium halides. This leads to luminescence quantum yields approaching unity while maintaining high charge mobilities along with the inhibition of transient photo-induced ion migration processes even in mixed halide perovskites that otherwise show bandgap instabilities. We demonstrate a wide range of bandgaps stabilized against photo-induced ion migration, leading to solar cell power conversion efficiencies of 21.6% for a 1.56 eV absorber and 18.3% for a 1.78 eV absorber ideally suited for tandem solar cells. We then systematically compare the optoelectronic properties and moisture stability of the two developed passivation routes for alloyed perovskites with rubidium and potassium where the latter passivation route showed higher stability and loading capacity leading to achieve substantially higher photoluminescence quantum yield. Finally, we explored the possibility of singlet exciton fission between low bandgap perovskites and tetracene as the triplet sensitizer finding no significant energy transfer between the two. We then used tetracene as an efficient dopant-free hole transport layer providing clean interfaces with perovskite layer leading to high photoluminescence yield (e.g. ~18%). To enhance the poor ohmic contact between tetracene and the metal electrode, we added capping layer of a second hole transport layer which is extrinsically doped leading to 21.5% power conversion efficiency for the subsequent solar cells and stabilised power output over 550 hours continuous illumination.
204

Metody analýzy vibračních signálů / Methods of analysis of vibration signals

Sivera, David January 2017 (has links)
The aim of the thesis is to focus on the different methods of analysis of vibration signals. Focusing on the physical fundamentals of vibrations and a description of their origin in an electrical machine. Describe the vibration sources from mechanical across the electromagnetic to the aerodynamic. Defining the current defects of electric machines and sensors suitable for the measurement of vibrations in an electric machines. Introduction to the methods of analysis of vibration signals in the time and frequency domain. Then using some of these methods for the analysis of vibration signals measured asynchronous motors with different manufacturer defined production defect. The conclusion is composed from the comparison between measured and analyzed results.
205

The Influence of Pile Shape and Pile Sleeves on Lateral Load Resistance

Russell, Dalin Newell 01 March 2016 (has links)
The lateral resistance of pile foundations is typically based on the performance of round piles even though other pile types are used. Due to lack of data there is a certain level of uncertainty when designing pile foundations other than round piles for lateral loading. Theoretical analyses have suggested that square sections will have more lateral resistance due to the increased side shear resistance, no test results have been available to substantiate the contention. Full-scale lateral load tests involving pile shapes such as circular, circular wrapped with high density polyethylene sheeting, square, H, and circular with a corrugated metal sleeve have been performed considering the influence of soil-pile interaction on lateral load resistance. The load test results, which can be summarized as a p-y curve, show higher soil resistance from the H and square sections after accounting for differences in the moment of inertia for the different pile sections. The increased soil resistance can generally be accounted for using a p-multiplier approach with a value of approximately 1.25 for square or 1.2 for H piles relative to circular piles. It has been determined that high density polyethylene sheeting provides little if any reduction in the lateral resistance when wrapped around a circular pile. Circular piles with a corrugated metal sleeve respond to lateral loading with higher values of lateral resistance than independent circular piles in the same soil.
206

En kapacitetsjämförelse mellan stålförstärktaträbalkar, limträ och konstruktionsvirke / A capacity comparison between flitch beam,construction timber and glulam

Gustavsson, Victor, Fabian, Hagenius January 2019 (has links)
Purpose: Throughout the years numerous studies have been made that concludes thatcombining steel and wood results in improved strength. Under optimal conditions woodis an effective structural material, as it’s both cheap and durable. Steel on the other handunder right circumstances has considerably higher strength than wood. To combinewood and steel has over the last years gathered more attention. Studies shows thathybrid structures can lead to an economical advantage when building multiple storeybuildings, as it can replace or complete pure steel frames. The purpose of this paper isto increase the knowledge and understanding of how steel and wood cooperate and tofind out the advantages and disadvantages of using a flitched beam, as well as compareit’s strength to structural wood and glulam.Method: The paper comprises a quantitative study with two different kinds of datacollection methods, Literature studies and calculations. The literature study consists ofscientific papers and papers published by known institutions and will help the paperanswer the first issue. The calculations has been made with the help of Tekla Tedds,which follows the Eurocode design principles. Which will help the authors answer bothof the papers issues.Findings: The paper has found that the flitch beam has improved strength overstructural wood and glulam, but a significantly higher price. The flitch beam also has amuch higher self weight than structural wood and glulam. The flitch beam can also spanlonger than structural wood and glulam with the same applied load.Implications: The study have concluded that it’s hard to motivate the usage of flitchedbeams in floor designs as they have such high price. The flitch beam has higher strengththan both structural wood and glulam. Which makes the flitch beam a good option asload bearing beam that requires slim dimensions. The added strength of the flitch beamcan motivate the high price under the right circumstances.Limitations: The paper has limited the calculations to an enclosed environment andwill not take moisture or any other type of exposure in to account, As a dry indoorenvironment is optimal for both steel and wood. The calculations the paper uses arebased on Eurocode and all other forms of dimension principles will not be taken intoaccount. / Syfte: Genom åren har forskning gjorts som tyder på att när man kombinerar stål ochträ kommer det bidra till en ökad hållfasthet. Under optimala förhållande är trä ettotroligt effektivt och bra alternativ inom byggande då det är billigt och tåligt. Närstålbalkar däremot placeras i optimala förhållande kan de bibehåll betydligt mer ochstörre krafter än vad trävirke kan göra. Att kombinera stål och trä har de senaste årethaft ett ökat intresse. Studier visar att hybridbalkar kan vara till stor ekonomisk fördelvid byggnation av flervåningshus, då det kan ersätta eller komplettera rena stålstommar.Syftet med arbete är att öka kunskapen och förståelsen för hur stål och trä samverkarsamt ta reda på för och nackdelar hos de stålförstärkta träbalkarna samt jämföra deraslastkapacitet med konstruktionsträ- och limträbalkar.Metod: Arbetet omfattar en kvantitativ studie där två typer av datainsamlingsmetoderhar använts. Dessa två typer är beräkningar samt litteraturstudier. Litteraturstudienbestår av vetenskapliga artiklar som har hjälpt besvara en av frågeställningarna.Beräkningarna har använts för att besvara båda frågeställningarna, de har gjorts idimensioneringsprogrammet Tekla tedds som följer alla Eurocodes beräknings- ochdimensioneringsregler.Resultat: Resultaten visar på att den stålförstärkta träbalken har högre kapacitet änlimträ och konstruktionsvirke, både med hänsyn till nedböjning och brott men betydligthögre pris och egentyngd. Den stålförstärkta träbalken klarar även av längrespännvidder vid samma belastning.Konsekvenser: Utifrån de resultat rapporten kommit fram till är det svårmotiverat attanvända sig av de stålförstärkta balkarna i bjälklag på grund av det höga priset Denstålförstärkta träbalken klarar dock av högre laster än vad konstruktionsvirke och limträgör, vilket kan göra balken användbar som avväxlingsbalk. Att använda denstålförstärkta träbalken som avväxlingsbalk kan motivera det höga priset då den kanhålla mindre dimensioner än limträ och konstruktionsvirke vilket kan vara önskvärt iolika sammanhang.Begränsningar: De begränsningar som sattes för rapporten var att utesluta alla typerav miljörisker på balkarna som tillexempel fukt och solljus vid beräkningarna, då entorrmiljö är en optimal miljö för både trä och stål. Beräkningarna som arbetet baseraspå grundar sig på Eurocodes dimensioneringsregler. Andra typer av dimensioneringsprinciper har uteslutits.
207

Development of ultra-precision tools for metrology and lithography of large area photomasks and high definition displays

Ekberg, Lars Peter January 2013 (has links)
Large area flat displays are nowadays considered being a commodity. After the era of bulky CRT TV technology, LCD and OLED have taken over as the most prevalent technologies for high quality image display devices. An important factor underlying the success of these technologies has been the development of high performance photomask writers in combination with a precise photomask process. Photomask manufacturing can be regarded as an art, highly dependent on qualified and skilled workers in a few companies located in Asia. The manufacturing yield in the photomask process depends to a great extent on several steps of measurements and inspections. Metrology, which is the focus of this thesis, is the science of measurement and is a prerequisite for maintaining high quality in all manufacturing processes. The details and challenges of performing critical measurements over large area photomasks of square meter sizes will be discussed. In particular the development of methods and algorithms related to the metrology system MMS15000, the world standard for large area photomask metrology today, will be presented. The most important quality of a metrology system is repeatability. Achieving good repeatability requires a stable environment, carefully selected materials, sophisticated mechanical solutions, precise optics and capable software. Attributes of the air including humidity, CO2 level, pressure and turbulence are other factors that can impact repeatability and accuracy if not handled properly. Besides the former qualities, there is also the behavior of the photomask itself that needs to be carefully handled in order to achieve a good correspondence to the Cartesian coordinate system. An uncertainty specification below 100 nm (3σ) over an area measured in square meters cannot be fulfilled unless special care is taken to compensate for gravity-induced errors from the photomask itself when it is resting on the metrology tool stage. Calibration is therefore a considerable challenge over these large areas. A novel method for self-calibration will be presented and discussed in the thesis. This is a general method that has proven to be highly robust even in cases when the self-calibration problem is close to being underdetermined. A random sampling method based on massive averaging in the time domain will be presented as the solution for achieving precise spatial measurements of the photomask patterns. This method has been used for detection of the position of chrome or glass edges on the photomask with a repeatability of 1.5 nm (3σ), using a measurement time of 250 ms. The method has also been used for verification of large area measurement repeatability of approximately 10 nm (3σ) when measuring several hundred measurement marks covering an area of 0.8 x 0.8 m2. The measurement of linewidths, referred to in the photomask industry as critical dimension (CD) measurements, is another important task for the MMS15000 system. A threshold-based inverse convolution method will be presented that enhances resolution down to 0.5 µm without requiring a change to the numerical aperture of the system. As already mentioned, metrology is very important for maintaining high quality in a manufacturing environment. In the mask manufacturing industry in particular, the cost of poor quality (CoPQ) is extremely high. Besides the high materials cost, there are also the stringent requirements placed on CD and mask overlay, along with the need for zero defects that make the photomask industry unique. This topic is discussed further, and is shown to be a strong motivation for the development of the ultra-precision metrology built into the MMS15000 system. / <p>QC 20130515</p>
208

Comparison Study of the Two Pediatric ATDs: Hybrid III 6-Year-Old and Q6

Jorlöv, Sofia, Hammarström, Jessica January 2011 (has links)
As a new pediatric dummy family, the Q-family, is suggested for the European childsafety regulations (R44) and the updated EuroNCAP, it needed to be tested andcompared to the older pediatric dummy family, Hybrid III, used in testing at Autolivtoday.In this study, tests were performed with the Q6 and the Hybrid III 6-year-old. Bothdummies were subjected to eight sled tests using a EuroNCAP acceleration pulse. The sled represented the interior of a Volvo V70, with integrated booster cushions mounted onto the car body through a rigid fixture. Standard belt were used for all tests, except one where pretensioning was used. Static tests investigated how the chest deflection on Q6 was affected by the shoulder belt geometry. Large difference in belt interaction was observed between the dummies. The beltslipped off the Hybrid III’s shoulder for all tests except one, while the belt on the Qdummy’swas hard to provoke off the shoulder. The overall kinematic behavior, beforethe belt slipped off the Hybrid III’s shoulder, were similar for both dummies. Differences in chest deflection on the Q6, depending on the belt geometry, were observed in both the dynamic and the static tests; a shoulder belt geometry closer to theneck resulted in minor displacement than a mid-shoulder belt geometry. After testing, five different damages were observed on the Q6. / Då en ny familj av barnkrockdockor, Q-familjen, är föreslagen för det europeiskalagkravet som reglerar barnsäkerhet (R44), uppstod ett behov av att testa och jämföradessa mot den äldre familjen av barnkrockdockor som används vid testning på Autoliv idag, Hybrid III. I den här studien utfördes tester på Q6 och Hybrid III 6 år. Båda dockorna utsattes föråtta stycken slädtest i en accelerationspuls enligt EuroNCAP. Släden representerade enVolvo V70 med integrerade barnkuddar som monterats i riggen via en stel fixtur. I alla test utom ett användes standardbälten (i undantagsfallet användes försträckare). Statiska tester gjordes för att undersöka hur Q6 påverkades av olika geometrier på axelbältet. Stora skillnader observerades mellan dockornas bältesinteraktion. Bältet gled av HybridIII:s axel i alla test förutom ett, medan det istället var svårt att provocera av bältet från Q-dockans axel. Innan Hybrid III gled ur bältet var dockornas kinematik liknande. I både statiska och dynamiska tester observerades skillnader i bröstintryckning på Q6, beroende på bältesgeometrin; en geometri där axelbältet var placerat nära nackenresulterade i en mindre intryckning än då axelbältet var placerat mitt på axeln. Efte ravslutad testning upptäcktes fem skador på Q6.
209

Behavior during construction of ramp B over I-40 in Nashville, TN

Dykas, Julia Catherine 06 April 2012 (has links)
The construction of curved I-girder bridges generally requires detailed attention to the steel erection plan as well as the deck placement sequence. There is limited quantitative information available on the performance of large curved bridges under construction. This study seeks to address this limitation through the study of a curved ramp I-girder bridge. The bridge under study is the last of several bridges needed to complete the interchange between I-40 and Briley Parkway (TN SR155) in western Nashville, TN. The study consists of three parts. First, the bridge was instrumented and its behavior during construction was monitored using vibrating wire strain gages, clinometers, and a robotic total station. Through these technologies it was possible to monitor changes in strain/stress, angle of rotation, and deflections throughout the girder erection, installation of concrete formwork, and concrete placement. Second, a static load test of the completed bridge was conducted using ten trucks loaded to a total weight of 72 kips each, during which measurements of the stress/strain and deflections were acquired. Finally, the collected data was compared to analytical results obtained from a 3D finite element analysis (FEA) model to assess the correlation between measurements and refined analytical predictions. The refined 3D FEA predictions are used as a baseline for evaluation of various simplified analysis methods in a parallel National Cooperative Highway Research Program project, NCHRP 12-79, Guidelines for Analytical Methods and Construction Engineering of Curved and Skewed Steel Girder Bridges. Overall, the comparisons show that the 3D FEA model provides a reasonable approximation of the bridge's behavior in terms of both stresses and deflections.
210

Development of the RDD portion of the total pavement acceptance device and its applications to jointed concrete pavement studies

Lee, Jung Su, active 21st century 09 February 2015 (has links)
A Rolling Dynamic Deflectometer (RDD) is a nondestructive testing device for determining continuous deflection profiles of pavements. Theses deflection profiles can be used more effectively when combined with other data such as pavement thickness, variability in moisture and other subsurface conditions, void detection and pavement right-of-way conditions. Therefore, a new, multi-function pavement testing device has been developed by a joint effort between the Texas Department of Transportation (TxDOT), the Center for Transportation Research (CTR) at the University of Texas at Austin (UT) and the Texas A&M Transportation Institute (TTI) at Texas A&M University. This new device is called the Total Pavement Acceptance Device (TPAD). The objective of TPAD testing is to nondestructively and nonintrusively investigate the structural adequacy of the total pavement system. The multiple functions of the TPAD presently include the following measurement capabilities: (1) rolling dynamic deflectometer (RDD), (2) ground penetrating radar (GPR), (3) global positioning (GPS), (4) pavement surface temperature, (5) digital video imaging of pavement and right-of-way conditions and (6) longitudinal survey offsets from known points through distance measurement (DMI). The TPAD is currently designed to perform continuous measurements at speeds around 2 to 3 mph. The effort in this dissertation is directed at: (1) developing the fourth-generation rolling sensors for faster testing speeds with the TPAD, (2) developing the Jointed Concrete Pavement (JCP) testbed with known and well-documented conditions (3) developing and evaluating the TPAD mobile platform, (4) evaluating the performance of the fourth-generation rolling sensors and refining a field calibration procedure and (5) studying the influence of the longitudinal and transverse joints in Jointed Concrete Pavement on TPAD deflection profile measurements. The first part involved the study of previous research and preliminary testing using the second-generation rolling sensor. Key benefits of the fourth-generation rolling sensor are: (1) reduced rolling noise during the testing, (2) higher signal-to-noise ratio (SNR), and (3) better tracking of the sensor. The second part of this work involved the development of the JCP testbed at the Texas Department of Transportation (TxDOT), Flight Services Facility (FSF) adjacent to the Austin-Bergstrom International Airport (ABIA). The JCP testbed was developed to establish a pavement facility with known and well-documented conditions for use in future research dealing with rigid pavement testing. The third part of this work involved the acceptance testing of the TPAD mobile platform for the RDD deflection measurements. The mobile platform was the one of the key components to develop the new moving pavement testing device. The TPAD mobile platform was developed by modifying a small, off-road vibroseies built by Industrial Vehicle International, Inc. (IVI). Acceptance testing of each of the following components was performed: (1) automated speed control, (2) static loading system and (3) dynamic loading system. The fourth part of this work involved the TPAD deflection measurements at the testbed at the TxDOT FSF. The deflection profiles using the fourth-generation rolling sensors and TPAD were performed at the established testbed. During the performance evaluation testing, the new sensor positioning, towing and raising/lowering system was developed and installed in the TPAD. The fifth part of this study involved the deflection measurement using the TPAD-RDD system on the jointed concrete pavement. This study includes the repeatability of the TPAD deflection measurements, the influence of the proximity to the longitudinal and transverse joints in JCP on TPAD deflection measurements, deflection measurements under different pavement surface temperature, the characteristic of the TPAD-RDD deflections and the comparison between the Falling Weight Deflectometer and TPAD deflection measurement testing. / text

Page generated in 0.0782 seconds