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  • 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.
21

Design and development of organically packaged components and modules for microwave and Mm-wave applications

Khan, Wasif Tanveer 12 January 2015 (has links)
Because of the tremendous amount of media streaming, video calling and high definition TV and gaming, the biggest challenge for the wireless industry is the increasing demand of high data rates. Utilization of mm-wave frequencies is an attractive option to meet this high demand. Recent advances in low cost semiconductor technologies allow realization of low-cost on-chip RF front-ends in the high millimeter wave (mm-wave) frequencies, making it possible to realize compact systems for these application areas. Although integrated circuits (ICs) are one of the main building blocks of a mm-wave system, in order to realize a fully functional wireless system, cost-effective antenna design and packaging are two important pre-conditions. Researchers have investigated and reported low-cost electronics packaging up to 100 GHz to a great extent on ceramic substrates, but mm-wave packaging above 100 GHz is relatively less explored, particularly on organic substrates. This Ph.D. dissertation demonstrates the design and development of microwave and mm-wave on-chip and on-package antennas and organically packaged components and modules ranging from 20 GHz to 170 GHz. The focus of this research was to design and develop mm-wave components and modules on LCP, to investigate the viability of this organic substrate and development of fabrication techniques in the K- (18-26.5 GHz), V- (50 to 70 GHz), W- (75 to 110 GHz), and D- (110 to 170 GHz) bands. Additionally, a demonstration of a micro-machined on-chip antenna has also been presented. This dissertation is divided in three parts: (1) characterization of liquid crystal polymer from 110 to 170 GHz. (2) development of highly radiation efficient on-chip and AiP antennas, and (3) development of mm-wave modules with the integration of antennas.
22

Avaliação do potencial do lodo oriundo de fossas/tanques sépticos domiciliares da Região Metropolitana de Cuiabá (RMC) para disposição final em solo agrícola

Silva, Joab Almeida da 04 November 2014 (has links)
Submitted by Valquíria Barbieri (kikibarbi@hotmail.com) on 2018-04-05T20:50:38Z No. of bitstreams: 1 DISS_2014_Joab Almeida da Silva.pdf: 3033730 bytes, checksum: 4a0f1680715be7f6554110dafd84ae3e (MD5) / Approved for entry into archive by Jordan (jordanbiblio@gmail.com) on 2018-04-23T16:57:12Z (GMT) No. of bitstreams: 1 DISS_2014_Joab Almeida da Silva.pdf: 3033730 bytes, checksum: 4a0f1680715be7f6554110dafd84ae3e (MD5) / Made available in DSpace on 2018-04-23T16:57:12Z (GMT). No. of bitstreams: 1 DISS_2014_Joab Almeida da Silva.pdf: 3033730 bytes, checksum: 4a0f1680715be7f6554110dafd84ae3e (MD5) Previous issue date: 2014-11-04 / O lodo de esgoto é um resíduo perigoso de acordo com a NBR 10.004/04, e quando mal gerenciado, pode afetar de modo adverso não apenas o meio ambiente como a saúde pública, por ser agente de propagação de doenças. Por outro lado, o biossólido obtido a partir do lodo de esgoto doméstico é considerado um ótimo biofertilizante devido à sua composição, por ser rico em matéria orgânica, nitrogênio e fósforo. Este trabalho teve como objetivo avaliar o potencial do lodo oriundo de fossas/tanques sépticos domiciliares da Região Metropolitana de Cuiabá (RMC) para disposição final em solos agrícolas. O experimento de leito de secagem natural foi desenvolvido em um laboratório terceirizado com o objetivo de avaliar a qualidade do lodo coletado em fossas sépticas dos bairros Dom Aquino, Coxipó da Ponte, Morada da Serra, Boa Esperança e Jardim Universitário e lodo transportado por veículos limpa-fossa. O experimento seguiu o mesmo procedimento de tratamento do lodo nas estações de tratamento de esgoto. Após esse processo, o material foi higienizado com cal virgem a 50% da base seca e submetido a um período de maturação de 30 dias, posteriormente foram submetidas a análises laboratoriais. Os parâmetros analisados foram com relação à estabilidade, a metais pesados e organismos patogênicos resistentes. Os resultados foram comparados com os padrões da legislação vigente. Também foram utilizadas técnicas de geoprocessamento e sistemas de informações geográficas (SIG) com objetivo de identificar as áreas potencialmente aptas para recebimento de biossólido. De acordo com os resultados obtidos, o leito de secagem de exposição natural apresentou eficiência na desidratação e estabilização do lodo, atingindo níveis menores que 10% de umidade e a relação entre sólidos voláteis e totais menores que 0,10; com relação às concentrações de elementos-traços de metais analisadas, todas as amostras de biossólidos apresentaram teores inferiores aos valores máximos permitidos pela Resolução CONAMA 375/06, inclusive a amostra do caminhão limpa-fossa, que apresentou os teores mais elevados dos parâmetros analisados; após a higienização do lodo, o material apresentou qualidade de biossólido classe A em relação à concentração de organismos patogênicos; por fim, o estudo do meio físico viabilizou a disposição do biossólido em pelo menos 75,30% (2.664,23 km²) da área do município, enquanto que 24,70% (873,93km²) apresentam restrições por se tratar de locais não recomendados para à aplicação desse tipo de material. / The sewage sludge is a hazardous waste according to NBR 10004/04, and when poorly managed, can adversely affect not only the environment and public health, to be the spread of disease agent. On the other hand, the sludge obtained from the sewage sludge is considered a great biofertilizer due to its composition, to be rich in organic matter nitrogen and phosphorus. This study aimed to evaluate the potential of the sludge coming from tanks / household septic tanks in the metropolitan region of Cuiabá (RMC) for final disposal on agricultural soils. The experiment of natural drying bed was developed in an outsourced laboratory with the aim of evaluating the quality of the sludge collected in pits neighborhoods Dom Aquino, Coxipó da Ponte, Morada da Serra, Boa Esperança and Jardim Universitário of septic tanks and transported by vehicles clean-pit. The experiment followed the same procedure in the treatment of sludge from sewage treatment plants. After this process, the material was sanitized with quicklime to 50% dry basis and undergo a maturation period of 30 days, then were subjected to laboratory analysis. The parameters were analyzed with respect to stability, the trace elements of metals and resistant pathogens. The results were compared with the current legislation standards. GIS techniques and geographic information systems (GIS) in order to identify potentially suitable for areas receiving biosolids were also used. According to the results, the drying bed natural exposure showed efficiency in dewatering and sludge stabilization, reaching levels lower than 10% humidity, the ratio between volatile and less than 0.10 total solids; with respect to the concentrations of trace elements of metals analyzed, all samples showed lower levels of biosolids to the maximum values allowed by CONAMA Resolution 375/06, including sample clean-truck fossa, which showed the highest levels of the analyzed parameters; after cleaning the sludge, the material presented quality Class A biosolids in relation to the concentration of pathogenic organisms; Finally, the study of the physical environment facilitated the disposal of biosolids at least 75.30% (2664.23 km ²) of the municipal area, while 24.70% (873,93km²) have restrictions because it is not local recommended for the application of this type of material.
23

Att lösa det olösta: hantering av destruktiva konfilkter : En kvalitativ studie om HRs utmaningar att hantera destruktiva konfilkter på arbetsplatsen / To solve the unsolved: managing destructive conflicts : A qualitative study about HRs challenges in handling destructive conflicts in the workplace

Johansson, Ellinor, Vidstrand, Nelly January 2023 (has links)
Syftet: Syftet med studien är att beskriva och utveckla förståelse för hur HR-personal hanterar destruktiva konflikter mellan personer på arbetsplatser. Fokus är på de utmaningar HR-personal upplever i konflikthanteringsprocessen. Metod: Studien har utförts genom en kvalitativ studie med en induktiv forskningsansats. Studien har tillämpat en undersökningsdesign likt en tvärsnittsstudie och datainsamlingen har skett genom ostrukturerade intervjuer. Slutsats: Studiens resultat visar att HR har ett antal utmaningar i sitt arbete för att hantera destruktiva konflikter på arbetsplatsen. HRs hanteringsprocess behöver vara situationsanpassad, därigenom använder HR olika tillvägagångssätt i sitt hanteringsarbete där HR-kollegors stöd beskrivs vara väsentligt. Vi konstaterar att många av utmaningarna grundar sig i att HRs arbete kopplat till konflikthantering handlar om människor. Komplexitet finns i att HR kommer in sent i processen, att hanteringen beror på mottagandet samt att det är svårt att veta vilka avväganden som krävs. Det påvisas däremot vara ytterst relevant att faktiskt hantera konflikten. / Purpose: The purpose of this study is to describe and develop an understanding of how HR-personnel handle destructive conflicts between people in workplaces. The focus is on the challenges HR-personnel experience in the conflict management process. Method: The study is conducted through a qualitative study with an inductive research approach. The study applied a survey design similar to a cross-sectional study and the data collection was carried out through unstructured interviews. Conclusion: The conclusion of the study shows that HR are facing a number of challenges in their work with handling destructive conflicts in the workplace. HRs managing process needs to adjust to the specific situation, therefore HR uses different approaches in their work and the support of HR-colleagues is described as essential. We have acknowledged that many of the challenges are based on the fact that their work concerns humans. Complexity is found in that HR are involved late in the handling process, their conflict management is depending on how the involved individuals receive HRs work and that it is difficult to know which choices to make. On the other hand, it is shown to be important to actually handle the conflict.
24

Development of multi-channel radio frequency technology for anatomical and functional magnetic resonance at Ultrahigh fields

Gräßl, Andreas 21 January 2017 (has links)
Magnetresonanztomographie (MRT) ist eine nichtinvasive Bildgebungsmethode, die in der Medizin sowie in der Forschung eingesetzt wird und auf der magnetischen Kernresonanz beruht. Die Erforschung der Ultrahochfeld (UHF) MRT ab Magnetfeldstärken von 7.0 Tesla und darüber ist durch einen intrinsischen Signalgewinn hin zu hohen Magnetfeldstärken motiviert und beschäftigt sich mit den dabei auftretenden physikalischen Effekten ebenso wie mit den dazu notwendigen neuartigen Technologien. Die vorliegende Arbeit untersucht Mehrkanalantennen zur Anregung der magnetischen Kernresonanz sowie zum Empfang des resultierenden Signals bei 7.0 T. Für die magnetische Kernresonanz von Protonen ergibt sich eine Resonanzfrequenz von 300 MHz. Die zugehörige Wellenlänge in menschlichem Gewebe verlässt in diesem Frequenzbereich im Verhältnis zu den Körperabmessungen den quasistatischen Bereich. Die sich ergebende Wellenausbreitung hat Interferenzmuster in den erzeugten Bildern zur Folge, die zu klinisch nicht verwertbaren Bildinformationen führen können. Vor diesem Hintergrund wurden in dieser Arbeit Mehrkanalantennen mit 4, 8 und 16 unabhängigen Elementen zur Signalanregung und zum Empfang konzipiert, aufgebaut und untersucht. Die Erkenntnisse mündeten in der erfolgreichen Implementierung der weltweit ersten 32-Kanal Antenne zur kardiovaskulären Bildgebung bei 7.0 T. Darüber hinaus wurde eine Antenne entwickelt, welche die ersten auf der Natriumkonzentration beruhenden bewegten MRT Bilder des menschlichen Herzens bei 7.0 T ermöglichte. Der Zusammenhang zwischen Natriumkonzentration und Zellintegrität ermöglicht direkte und ortsaufgelöste Einblicke in physiologische Prozesse. Die Ergebnisse dieser Arbeit belegen die breite Anwendbarkeit von Mehrkanalantennen in der UHF MRT zur Protonen-und Natriumbildgebung und bilden eine solide technologische Basis für breitere klinische Studien, um die Ultrahochfeld MRT reif für den routinemäßigen Einsatz im Gesundheitswesen zu machen. / Magnetic resonance imaging (MRI) is a non-invasive imaging method based on the effect of nuclear magnetic resonance. It is used in healthcare as well as in research. MRI at magnetic field strengths of 1.5 Tesla and 3 Tesla is well established. The gain in signal-to-noise ratio (SNR) intrinsic to higher magnetic field strength fuels the vigorous research field of Ultrahigh field (UHF) MRI at 7.0 T and above. Nevertheless for MRI based upon proton imaging the wavelength of the transmitted electro-magnetic fields slowly departs from the semi-static regime and reaches the dimension of the transection of the human body at 7.0 T. This gives rise to constructive and destructive interferences that potentially render image quality non-diagnostic for clinical use. Therefore is work proposes the worlds’ first 32 channel antenna array for cardiovascular MRI at 7.0 T. Electro-magnetic field simulations are utilized to study the capabilities of multi-channel RF antenna arrays to mitigate destructive interferences and provided the basis for a workflow towards homogenization of the electromagnetic radio-frequency field. Pre-clinical studies showed the capabilities and limits of translating the SNR gain of UHF MRI into clinical beneficial numbers, namely increased spatial or temporal resolution or scan time shortening. To make further use of the benefits of UHR MRI and to make a step towards first-hand spatial resolved information of biological processes in human tissue sodium imaging of the human heart was enabled with the design of a tailored antenna array. The results were reconstructed into the first movies of the human heart at 7.0 T based on sodium signal. This profound technological basis for radio frequency excitation and reception in UHF MRI can be expected to pave the way for broader clinical studies at 7.0 T with the ultimate goal to improve the quality and the earliness of treatment decisions in future clinical practice.
25

An Analysis of Wireless High-speed Data Services for Cellular CDMA Systems

Chan, Kwong Hang Kevin January 2002 (has links)
The interest in the development of wireless high-speed data services is in response to the strong market demand for high-speed wireless Internet access. Current standards aim at delivering a peak data rate greater than 2Mbps on the forward link. Since data services and voice services are fundamentally different, new concepts were introduced in the design of the forward data channel. In addition, methods of evaluating the performance of a cellular CDMA system have to be revisited. This thesis proposes a method which can be used to find the forward link peak and average data rates, throughput and coverage of a cellular CDMA system which is capable of delivering high-speed wireless data. A summary of changes in design philosophy and recent advances in technologies which enable high-speed wireless data delivery are presented. The proposed method takes into account major aspects commonly found in the forward data channel and applies the generalized Shannon capacity formula for multi-element antenna (MEA) systems. The analysis focuses on the physical layer and is flexible enough to be adapted to various propagation environments, antenna configurations, multicode allocations, user distributions and cell site configurations. Sample numerical results for various multicode allocations are shown using a system model with two-tier interfering cells with one transmit antenna and two receive antennas operating under a frequency selective slow fading channel with propagation environment described by the Recommendation ITU-R M. 1225 indoor office, outdoor to indoor and pedestrian and vehicular test environments. Different transmit / receive antenna configurations and multicode allocations and their impact on the average data rate is also explored.
26

An Analysis of Wireless High-speed Data Services for Cellular CDMA Systems

Chan, Kwong Hang Kevin January 2002 (has links)
The interest in the development of wireless high-speed data services is in response to the strong market demand for high-speed wireless Internet access. Current standards aim at delivering a peak data rate greater than 2Mbps on the forward link. Since data services and voice services are fundamentally different, new concepts were introduced in the design of the forward data channel. In addition, methods of evaluating the performance of a cellular CDMA system have to be revisited. This thesis proposes a method which can be used to find the forward link peak and average data rates, throughput and coverage of a cellular CDMA system which is capable of delivering high-speed wireless data. A summary of changes in design philosophy and recent advances in technologies which enable high-speed wireless data delivery are presented. The proposed method takes into account major aspects commonly found in the forward data channel and applies the generalized Shannon capacity formula for multi-element antenna (MEA) systems. The analysis focuses on the physical layer and is flexible enough to be adapted to various propagation environments, antenna configurations, multicode allocations, user distributions and cell site configurations. Sample numerical results for various multicode allocations are shown using a system model with two-tier interfering cells with one transmit antenna and two receive antennas operating under a frequency selective slow fading channel with propagation environment described by the Recommendation ITU-R M. 1225 indoor office, outdoor to indoor and pedestrian and vehicular test environments. Different transmit / receive antenna configurations and multicode allocations and their impact on the average data rate is also explored.
27

Studies of Electromagnetic Backscattering from Ocean Surfaces

Wijesundara, Shanka N. January 2019 (has links)
No description available.
28

Felinus Domus: A Veterinary Hospital for Cats in Old Town Alexandria, Virginia

Butterworth, Mary Michele 15 April 2008 (has links)
Throughout time man has discovered that the human form, in all its harmonious proportion, can be used as a guide, gauge and tool to design and build structures. However, the human figure has not been the only organic form used to create architecture. Many animals create dwellings that synchronize with not only their own unique physical characteristics and survival instincts, but with their aesthetic preferences as well. It is logical that a design should respond to its surroundings, program and most importantly, its inhabitants. This thesis design is for two specific occupants: the cat and the human. They are both meant to inhabit the building wholly and simultaneously. The way each of them experiences and uses the space, however, differs greatly. For a building to survive it needs many of the same things as living creatures: sunlight, air and movement, to name a few. It also needs to function like a living creature. It must breathe, sleep, respond to the changing seasons, and adapt over time. This thesis is an investigation of how both human and cat can dwell in a building of harmonious proportion, scale, light, and material. / Master of Architecture
29

Silicon-Based PALNA Transmit/Receive Circuits for Integrated Millimeter Wave Phased Arrays

Abdomerovic, Iskren 08 January 2020 (has links)
Phased array element RF front ends typically use single pole double throw (SPDT) switches or circulators with high isolation to prevent leakage of transmit energy into the receiver circuits. However, as phased-array designs scale to the millimeter-wave range, with high degrees of integration, the physical size and performance degradations associated with switches and circulators can present challenges in meeting system performance and size/weight/power (SWAP) requirements. This work demonstrates a loss-aware methodology for analysis and design of switchless transmit/receive (T/R) circuits. The methodology provides design insights and a practical, generally applicable approach for solving the multi-variable optimization problem of switchless power amplifier/low-noise amplifier (PALNA) matching networks, which present optimal matching impedances to both the power amplifier (PA) and the low noise amplifier (LNA) while maximizing power transfer efficiency and minimizing dissipative losses in each (transmit or receive) mode of operation. Three PALNA example designs at W-band are presented in this dissertation, each following a distinct design methodology. The first example design in 32SOI CMOS leverages PA and LNA circuits that already include 50 Ω matching networks at both input and output. The second example design in 8XP SiGe develops the PA and LNA circuits and integrates the PA output and LNA input matching networks into the PALNA matching network that connects the PA and the LNA. The third design in 32SOI CMOS leverages the loss-aware PALNA design methodology to develop a PALNA that achieves simulated maximum power added efficiency of 18 % in transmit and noise figure of 7.5 dB in receive at 94 GHz, which is beyond the published state-of-art for T/R circuits. In addition, for comparison purposes, this dissertation also presents an efficient, switch-based T/R circuit design in 32SOI CMOS technology, which achieves a simulated maximum power added efficiency of 15 % in transmit and noise figure of 6.5 dB in receive at 94 GHz, which is also beyond the published state-of-art for T/R circuits. / Doctor of Philosophy / In military and commercial applications, phased arrays are devices primarily used to achieve focusing and steering of transmitted or received electromagnetic energy. Phased arrays consist of many elements, each with an ability to both transmit and receive radio frequency (RF) signals. Each element incorporates a power amplifier (PA) for transmit and a low noise amplifier (LNA) for receive, which are typically connected using a single pole double throw (SPDT) switch or a circulator with high isolation to prevent leakage of transmit energy into the receiver circuits. However, as phased arrays exploit the latest technological advances in circuit integration and their frequencies of operation increase, physical size and performance degradations associated with switches and circulators can present challenges in meeting system performance and size/weight/power (SWAP) requirements. This dissertation provides a loss-aware methodology for analysis and design of switchless transmit/receive (T/R) circuits where the switches and circulators are replaced by carefully designed power amplifier/low-noise amplifier (PALNA) impedance matching networks. In the switchless T/R circuits, the design goals of maximum power efficiency and minimum noise in transmit and receive, respectively, are achieved through impedance matching that is optimal and low-loss in both modes of operation simultaneously. Three distinct PALNA example designs at W-band are presented in this dissertation, each following a distinct design methodology. With each new design, lessons learned are leveraged and design methodologies are enhanced. The first example design leverages already available PA and LNA circuits and connects them using 50 Ω transmission lines whose lengths are designed to guarantee optimum impedance match in receive and transmit mode of operation. The second example design develops new PA and LNA circuits and connects them using 50 Ω transmission lines whose lengths are designed to simultaneously achieve optimum impedance matching for maximum power efficiency in transmit mode of operation and lowest noise in receive mode of operation. The third design leverages a loss-aware PALNA design methodology, a multi-variable optimization procedure, to develop a PALNA that achieves simulated maximum power added efficiency of 18 % in transmit and noise figure of 7.5 dB in receive at 94 GHz, which is beyond the published state-of-art for T/R circuits. In addition, for comparison purposes with the third PALNA design, this dissertation also presents an efficient, switch-based T/R circuit design, which achieves a simulated maximum power added efficiency of 15 % in transmit and noise figure of 6.5 dB in receive at 94 GHz, which is also beyond the published state-of-art for T/R circuits.
30

Telemetry Receive/Record & Re-Radiation Pod

Johnson, Bruce 10 1900 (has links)
ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / This paper discusses the mission needs, design/development, and testing of the (L, S & C Band) Telemetry Receive/Record & Re-Radiation pod.

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