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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.
71

Towards Automated Design of Toggle Switch Mechanisms

Kalyan Ramana, G January 2016 (has links) (PDF)
This work deals with addressing the issues related to design of double toggle switch mechanisms with emphasis on structural, dimensional and dynamic aspects. Currently, almost all the issues related to electrical switches are dealt from electromagnetic point of view; the operating mechanism is hardly touched. It is observed that kinematic parameters influence electrical performance of switch significantly. Therefore, there is a need to develop methodologies for supporting exploration of diverse kinematic chains (KCs) for this purpose. Visual inspection is tedious and error prone even when a complete list of design criteria is available, hence, the work presented in the thesis contributes towards automated design of toggle switch mechanisms. In this context, in house modular kinematics data structure is found useful for using it as a tool in the design of toggle switch. Modular kinematics, typically used for kinematic analysis, works on the principle of finding the configuration of a mechanism using a given set of modules by a procedure called module sequence. This module sequence is used and interpreted in a number of ways for its effective use in various design stages. Structurally, a set of seven conditions must be satisfied by a KC to exhibit double toggle. These conditions are broadly classified into three categories: criteria for KC, function assignment criteria and criteria for stoppers. These three criteria are to be checked automatically by use of module sequence in the same order as mentioned. In the criteria for KC, one of the conditions is that, the KC should not have fractionated degrees of freedom (d.o.f.). Hence, detection of fractionation in a KC is inevitable. In literature, is was found that the algorithms for detection operate at their worst case complexity, O(n4), and some of them do not report joint fractionation. Thus, the algorithms are not only robust but also computationally expensive. Therefore, a frugal and comprehensive method O(n2) is implemented to detect fractionation using modular kinematics. Also, inherent structural pattern embedded in fractionated KCs is hardly studied in literature. It is found that the way body and joint fractionation is defined in fractionated KCs is inconsistent. So, fractionation is interpreted as symbolic partitioning of joints and links in the traditional body and joint fractionation types respectively. Based on the number of ways of partitioning, simple and multiple types of fractionation are recognized. Valid partitions are identified using the notion of fractionating and non-fractionating subchains. Relative locations of these subchains influence distribution of d.o.f. across the fractionated KC. Conventional representation of KCs as links and joints or graphs is difficult to comprehend this distribution. For this, a novel concept of fractionation graph is introduced that gives d.o.f. distribution information and the relative locations of the constituent subchains across the KC. Modular kinematics gives a constructive description of fractionated KCs. Characterization of fractionated KCs, based on presence of multiple separation links, is introduced as order of fractionation. Uniqueness for a given order of fractionation is also justified. After the criteria for KC, a KC is tested for feasibility for function assignment criteria. This requires recognition of active and passive subchains of the KC with respect to input and output pairs. For this, module sequence is characterized for recognition of the subchains. Based on these subchains, locations of stoppers are derived. Using this information, an algorithmic approach to assign functions (functions like spring, ground link, input link, etc.) to derive distinct driving mechanisms provided isomorphic elements (links and joints) of the KC are known beforehand, is introduced. The design parameters influencing dimensional synthesis have been identified as dimensions of links, spring anchor points and stopper locations. Sub-problems associated with each parameter are analyzed. It is found out that optimum location of stoppers for selecting operational range of motion is necessary by taking into account the considerations of timing of switch and impact velocity. Based on the analysis, an algorithmic way to design single toggle switch mechanisms is introduced. Timing for closing or opening of a switch is one of the critical measure that determines its performance. Timing should be as low as possible without exceeding the impact velocity at the instant contacts meet each other. Timing of a switch depends on the dimensions of the links, inertial parameters, spring stiffness etc. For a given timing for a mechanism, dynamic synthesis, in this thesis, deals with finding the inertial parameters of the links using Quinn's energy distribution method, modular kinematics, and Nelder and Mead's downhill simplex method for optimization. This thesis helps the designer to use modular kinematics as a potential automated tool to select a valid design to make the solution space more meaningful in the design of toggle switch mechanisms.
72

B-2 Flight Test Implementation of an Ethernet Based Network System for Data Acquisition

Hochner, William "Bill" 10 1900 (has links)
ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV / Northrop Grumman Corporation's B-2 Flight Test Instrumentation team is revamping its entire Data Acquisition System (DAS) to be an Ethernet based network (EBN) system that will provide simplified wiring, higher speeds, greater capacity, and control over the data. The old system became obsolete in terms of capability and maintainability. New on-board avionic systems also demand that the Flight Test Instrumentation group (INSTR) accommodate fiber and high speed Ethernet data. In addition, the footprint and location for INSTR systems and components will be moved to remote areas. INSTR engineering selected the Teletronics Technology Corporation's Ethernet networked Data Acquisition Units (DAUs), known as MnDAUs, as the core system. Prior to the first flight utilization of the new INSTR DAS will undergo extensive lab and field testing to assure flight test effectiveness and the accuracy of all necessary data products. The goal is to acquire and employ the best system available while avoiding costly lessons.
73

Computational Studies of Electron Transport in Nanoscale Devices

Löfås, Henrik January 2013 (has links)
In this thesis, a combination of density functional theory (DFT) based calculations and nonequilibrium Green’s functions are employed to investigate electron transport in molecular switches, molecular cords and nanoscale devices.   Molecular electronic devices have been proposed as an approach to complement today’s silicon based electronic devices. However, engineering of such miniature devices and design of functional molecular components still present significant challenges.   First, the way to connect a molecule to conductive electrodes has to be controlled. We study, in a nanoelectrode-nanoparticle platform, how structural changes affect the measured conductance and how current fluctuations due to these structural changes can be decreased. We find that, for reproducible measurements, it is important to have the molecules chemically bonded to the surfaces of adjacent nanoparticles. Furthermore, we show by a combination of DFT and theoretical modeling that we can identify signals from single-molecules in inelastic electron spectroscopy measurements on these devices.   Second, active elements based on molecules, some examples being switches, rectifiers or memory devices, have to be designed. We study molecular conductance switches that can be operated by light and/or temperature. By tuning the substituents on the molecules, we can optimize the shift of the most conducting molecular orbital and increase the effective coupling between the molecule and the electrodes when going from the OFF to the ON-state of the switches, giving high switching ratio (up to three orders of magnitude). We also study so called mechanoswitches that are activated by a mechanical force elongating the molecules, which means that these switches could operate as sensors.   Furthermore, we have studied two different classes of compounds that may function either as rigid molecular spacers with a well-defined conductance or as molecular cords. In both cases, we find that it is of great importance to match the conjugation of the anchoring groups with the molecular backbone for high conductance.   The last part of the thesis is devoted to another interesting semiconductor material, diamond. We have accurately calculated the band structure and effective masses for this material. Furthermore, these results have been used to calculate the Hall coefficient, the resistivity and the Seebeck coefficient.
74

Platinum pincer complexes : in pursuit of switchable materials

Bryant, Mathew James January 2016 (has links)
The research presented within this thesis is concerned with the design, synthesis, characterisation, and analysis of a series of new compounds of platinum (II), with aims to produce compounds possessing switchable optical properties, and with potential applications as "smart-materials" for use as highly selective sensors.
75

Análise dos papéis de compra no processo de aquisição de interruptores por clientes finais

Lahm, Rudinei Luis da Fonseca January 2017 (has links)
O presente estudo tem como objetivo identificar os papéis na compra de interruptores de luz por clientes finais e identificar as influências desses papéis e como ocorrem. O método utilizado foi dividido em duas fases, a primeira com abordagem qualitativa e a segunda com abordagem quantitativa. Inicialmente foram feitas entrevistas em profundidade com consumidores e profissionais da área, com o objetivo de identificar quais os tipos de papéis que ocorrem durante a compra de interruptores e identificar os influenciadores. O segundo passo foi uma survey, sendo entrevistadas 1.013 pessoas divididas nas cinco regiões do país, Região Centro Oeste, Nordeste, Sul, Norte e Sudeste. Foram identificados cinco papéis de compra e sete influenciadores desse processo. Os resultados da pesquisa quantitativa foram analisados com análises univariadas e multivariadas. As análises indicam que os compradores adquirem interruptores para outros usuários, mas a grande maioria deles adquirem o produto para uso próprio e são responsáveis pela compra e pelo pagamento do produto. Os resultados também indicam que as pessoas próximas são os maiores influenciadores. Espera-se que com os resultados obtidos esse trabalho possa contribuir para executivos e empresas do setor elétrico na tomada de decisões. / The present paper has the objective to identify which are the final consumers purchase roles of light switches and identify the influences about this roles and how it occurs. The analysis method was dividing in two steps, the first with a qualitative approach and the second with a quantitative approach. First of all, had been made depth interviews with consumers and professionals from the area, with the objective to identify the influencers. After that, a survey has been made, 1.013 people were interviewed and divided at five regions of the country, Midwest region, Northeast, South, North and Southeast. Were identified five purchase roles and seven influencers of this process. The quantitative research results were analyzed with univariate and multivariate analysis. The analysis indicate that the buyers also buy the light switches for other users, but the majority buy the product for own use and is responsible for the purchase and the product payment. The results also indicate that, in general, close people are the major influencers. With the obtained results throw crossing and the performed analyses, the expectations with this paper is contribute with executives and companies of the area on theirs decision-making.
76

Design and Evaluation of the Combined Input and Crossbar Queued (CICQ) Switch

Yoshigoe, Kenji 09 August 2004 (has links)
Packet switches are used in the Internet to forward information between a sender and receiver and are the critical bottleneck in the Internet. Without faster packet switch designs, the Internet cannot continue to scale-up to higher data rates. Packet switches must be able to achieve high throughput and low delay. In addition, they must be stable for all traffic loads, must efficiently support variable length packets, and must be scalable to higher link data rates and greater numbers of ports. This dissertation investigates a new combined input and crossbar queued (CICQ) switch architecture. Some unbalanced traffic loads result in instability for input queued (IQ) and CICQ switches. This instability region was modeled, and the cause of the instability was found to be a lack of work conservation at one port. A new burst stabilization protocol was investigated that was shown to stabilize both IQ and CICQ switches. As an added benefit, this new protocol did not require a costly internal switch speed-up. Switching variable length packets in IQ switches requires the segmentation of packets into cells. The process also requires an internal switch speed-up which can be costly. A new method of cell-merging in IQ switches reduced this speed-up. To improve fairness for CICQ switches, a block and transfer method was proposed and evaluated. Implementation feasibility of the CICQ switch was also investigated via a field programmable gate array (FPGA) implementation of key components. Two new designs for round robin arbiters were developed and evaluated. The first of these, a proposed priority-encoder-based round robin arbiter that uses feedback masking, has a lower delay than any known design for an FPGA implementation. The second, an overlapped round robin arbiter design that fully overlaps round robin polling and scheduling, was proposed and shown to be scalable, work conserving, and fair. To allow for multi-cabinet implementation and minimization of the size of the cross point buffers, a distributed input port queue scheduler was investigated. This new scheduler minimizes the amount of buffering needed within the crossbar. The two primary contributions of this dissertation are 1) a complete understanding of the performance characteristics of the CICQ switch, and 2) new methods for improving the performance, stability,and scalability of the CICQ switch. This work has shown that the CICQ switch can be the switch architecture of the future.
77

A High-Temperature, High-Voltage SOI Gate Driver Integrated Circuit with High Drive Current for Silicon Carbide Power Switches

Huque, Mohammad Aminul 01 May 2010 (has links)
High-temperature integrated circuit (IC) design is one of the new frontiers in microelectronics that can significantly improve the performance of the electrical systems in extreme environment applications, including automotive, aerospace, well-logging, geothermal, and nuclear. Power modules (DC-DC converters, inverters, etc.) are key components in these electrical systems. Power-to-volume and power-to-weight ratios of these modules can be significantly improved by employing silicon carbide (SiC) based power switches which are capable of operating at much higher temperature than silicon (Si) and gallium arsenide (GaAs) based conventional devices. For successful realization of such high-temperature power electronic circuits, associated control electronics also need to perform at high temperature. In any power converter, gate driver circuit performs as the interface between a low-power microcontroller and the semiconductor power switches. This dissertation presents design, implementation, and measurement results of a silicon-on-insulator (SOI) based high-temperature (>200 _C) and high-voltage (>30 V) universal gate driver integrated circuit with high drive current (>3 A) for SiC power switches. This mixed signal IC has primarily been designed for automotive applications where the under-hood temperature can reach 200 _C. Prototype driver circuits have been designed and implemented in a Bipolar-CMOS- DMOS (BCD) on SOI process and have been successfully tested up to 200 _C ambient temperature driving SiC switches (MOSFET and JFET) without any heat sink and thermal management. This circuit can generate 30V peak-to-peak gate drive signal and can source and sink 3A peak drive current. Temperature compensating and temperature independent design techniques are employed to design the critical functional units like dead-time controller and level shifters in the driver circuit. Chip-level layout techniques are employed to enhance the reliability of the circuit at high temperature. High-temperature test boards have been developed to test the prototype ICs. An ultra low power on-chip temperature sensor circuit has also been designed and integrated into the gate-driver die to safeguard the driver circuit against excessive die temperature (_ 220 _C). This new temperature monitoring approach utilizes a reverse biased p-n junction diode as the temperature sensing element. Power consumption of this sensor circuit is less than 10 uW at 200 _C.
78

Quantum dynamical study of Si(100) surface-mounted, STM-driven switches at the atomic and molecular scale

Zenichowski, Karl January 2012 (has links)
The aim of this thesis is the quantum dynamical study of two examples of scanning tunneling microscope (STM)-controllable, Si(100)(2x1) surface-mounted switches of atomic and molecular scale. The first example considers the switching of single H-atoms between two dangling-bond chemisorption sites on a Si-dimer of the Si(100) surface (Grey et al., 1996). The second system examines the conformational switching of single 1,5-cyclooctadiene molecules chemisorbed on the Si(100) surface (Nacci et al., 2008). The temporal dynamics are provided by the propagation of the density matrix in time via an according set of equations of motion (EQM). The latter are based on the open-system density matrix theory in Lindblad form. First order perturbation theory is used to evaluate those transition rates between vibrational levels of the system part. In order to account for interactions with the surface phonons, two different dissipative models are used, namely the bilinear, harmonic and the Ohmic bath model. IET-induced vibrational transitions in the system are due to the dipole- and the resonance-mechanism. A single surface approach is used to study the influence of dipole scattering and resonance scattering in the below-threshold regime. Further, a second electronic surface was included to study the resonance-induced switching in the above-threshold regime. Static properties of the adsorbate, e.g., potentials and dipole function and potentials, are obtained from quantum chemistry and used within the established quantum dynamical models. / Die vorliegende Doktorarbeit befasst sich mit kleinsten schaltbaren Einheiten in Form des Moleküls Cyclooctadien (COD) und dem Wasserstoff-Atom, die chemisch fest mit einer Oberfläche aus kristallinem Silizium verbunden sind. Jeder dieser Schalter kann mittels einer winzigen Spitze, eines so genannten Rastertunnelmikroskops (RTM), von atomarem Durchmesser in zwei unterscheidbare und stabile Schaltpositionen gebracht werden. Dabei besteht das Schalten entweder in einer Änderung der Geometrie des molekularen Schalters oder im Brechen und Neu-knüpfen chemischer Bindungen. Dabei ist es entscheidend, dass durch die geringe Grösse dieser Schalter eine hohe Anzahl dieser Schalter auf einer Oberfläche deponiert werden können. Mit der in den Schaltern speicherbaren Informationen an oder aus, 0 oder 1 ließen sich sehr hohe Speicherkapazitäten erreichen. Vor einer Anwendung dieser Art ist es wichtig zunächst ein grundlegendes Verständnis der Schaltprozesse auf der Oberfläche zu gewinnen. Wenn alle wesentlichen Faktoren berücksichtigt wurden und der Mechanismus des Schaltens verstanden ist, kann das Ergebnis des Experiments mit Hilfe eines theoretischen Modells vorhergesagt werden. Für die Handhabbarkeit muss sich das theoretisches Modell auf wesentliche Einflüsse beschränken und diese so einfach wie möglich beschreiben. So wurde die simultane Bewegung der 12 Atome des COD in die Bewegung eines gemittelten Massenpunktes entlang von einer oder von zwei räumlichen Freiheitsgraden übersetzt. Dabei kann der Massenpunkt im klassischen Bild anschaulich als eine rollende Kugel beschrieben werden, die in einer Seite einer Doppelmulde gefangen ist. Die Kugel kann durch äußere Anregung zum Schwingen gebracht werden und schließlich über eine Barriere in die benachbarte Mulde schalten. Nun muss die Schwingung der Kugel gebremst werden, um ein Zurück-Schwingen der Kugel zu verhindern. Die Anregung erfolgt durch elektrische Ladungen die von der Spitze des RTM zur Oberfläche wandern oder durch eine schwingende, d.h. warme Oberfläche. Das Bremsen wird über die elastische Bindung zu einer kalten Oberfläche vermittelt. Um Quanteneffekte wie das Tunneln der Kugel durch die Barriere zu beschreiben wurde die Kugel durch ein Wellenpaket beschrieben und dessen Aufenthaltswahrscheinlichkeit in der Doppelmulde untersucht. Im Fall des Wasserstoffatoms war die experimentelle Prüfung des entworfenen Modells für ein Schalten bei starkem Strom leider nicht möglich. Für das COD Molekül konnte jedoch nicht nur die Übereinstimmung mit den experimentellen Befunden, sondern im Fall des Schaltens in Abhängigkeit der Oberflächentemperatur auch die Vorhersagefähigkeit des Modells unter Beweis gestellt werden.
79

W-Band Passive and Active Circuits in 65-nm Bulk CMOS for Passive Imaging Applications

Tomkins, Alexander 07 April 2010 (has links)
The design and implementation of mm-wave switches, variable attenuators, and a passive imaging system in 65-nm CMOS are presented. The design and analysis of shunt switches is presented with a demonstration circuit showing record performance for a single-pole single-throw switch with 1.6dB loss and 30dB isolation at 94GHz. Single-pole double-throw (SPDT) switches are shown, with 4dB insertion loss in the W-band (75-110GHz), and the only reported SPDT switch operating in the D-band (110-170GHz). A novel technique for implementing digitally controlled variable attenuation is presented, resulting in variable attenuation between 4 and 30dB in the W-band. Finally, a W-band radiometer is described integrating a record-high gain CMOS LNA, SPDT switch, and peak detector. This is the highest-frequency imaging system in CMOS with this level of integration, offering a responsivity over 90kV/W, and a noise-equivalent power less than 0.2pW/√Hz.
80

W-Band Passive and Active Circuits in 65-nm Bulk CMOS for Passive Imaging Applications

Tomkins, Alexander 07 April 2010 (has links)
The design and implementation of mm-wave switches, variable attenuators, and a passive imaging system in 65-nm CMOS are presented. The design and analysis of shunt switches is presented with a demonstration circuit showing record performance for a single-pole single-throw switch with 1.6dB loss and 30dB isolation at 94GHz. Single-pole double-throw (SPDT) switches are shown, with 4dB insertion loss in the W-band (75-110GHz), and the only reported SPDT switch operating in the D-band (110-170GHz). A novel technique for implementing digitally controlled variable attenuation is presented, resulting in variable attenuation between 4 and 30dB in the W-band. Finally, a W-band radiometer is described integrating a record-high gain CMOS LNA, SPDT switch, and peak detector. This is the highest-frequency imaging system in CMOS with this level of integration, offering a responsivity over 90kV/W, and a noise-equivalent power less than 0.2pW/√Hz.

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