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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.
221

Structural Estimation Using Sequential Monte Carlo Methods

Chen, Hao January 2011 (has links)
<p>This dissertation aims to introduce a new sequential Monte Carlo (SMC) based estimation framework for structural models used in macroeconomics and industrial organization. Current Markov chain Monte Carlo (MCMC) estimation methods for structural models suffer from slow Markov chain convergence, which means parameter and state spaces of interest might not be properly explored unless huge numbers of samples are simulated. This could lead to insurmountable computational burdens for the estimation of those structural models that are expensive to solve. In contrast, SMC methods rely on the principle of sequential importance sampling to jointly evolve simulated particles, thus bypassing the dependence on Markov chain convergence altogether. This dissertation will explore the feasibility and the potential benefits to estimating structural models using SMC based methods.</p><p> Chapter 1 casts the structural estimation problem in the form of inference of hidden Markov models and demonstrates with a simple growth model.</p><p> Chapter 2 presents the key ingredients, both conceptual and theoretical, to successful SMC parameter estimation strategies in the context of structural economic models.</p><p> Chapter 3, based on Chen, Petralia and Lopes (2010), develops SMC estimation methods for dynamic stochastic general equilibrium (DSGE) models. SMC algorithms allow a simultaneous filtering of time-varying state vectors and estimation of fixed parameters. We first establish empirical feasibility of the full SMC approach by comparing estimation results from both MCMC batch estimation and SMC on-line estimation on a simple neoclassical growth model. We then estimate a large scale DSGE model for the Euro area developed in Smets and Wouters (2003) with a full SMC approach, and revisit the on-going debate between the merits of reduced form and structural models in the macroeconomics context by performing sequential model assessment between the DSGE model and various VAR/BVAR models.</p><p> Chapter 4 proposes an SMC estimation procedure and show that it readily applies to the estimation of dynamic discrete games with serially correlated endogenous state variables. I apply this estimation procedure to a dynamic oligopolistic game of entry using data from the generic pharmaceutical industry and demonstrate that the proposed SMC method can potentially better explore the parameter posterior space while being more computationally efficient than MCMC estimation. In addition, I show how the unobserved endogenous cost paths could be recovered using particle smoothing, both with and without parameter uncertainty. Parameter estimates obtained using this SMC based method largely concur with earlier findings that spillover effect from market entry is significant and plays an important role in the generic drug industry, but that it might not be as high as previously thought when full model uncertainty is taken into account during estimation.</p> / Dissertation
222

Reconfigurable equalization for 10-Gb/sec serial data links in a 0.18-μm CMOS technology

Bien, Franklin Young-Jae 13 November 2006 (has links)
The objective of the proposed research is to realize a 10-Gb/sec serial data link over band-limited channels, such as backplanes, multi-mode fiber, and copper-based cables that were originally designed for data rates less than 1Gb/sec. This is achieved using electrical equalization implemented in an integrated circuit (IC). To successfully compensate for various band-limited channels at the targeted data rate with a single equalizer IC, a reconfigurable equalizer topology is proposed. In order to realize the proposed goal, various channels are characterized of their forward transmission frequency response. Based on the measured channel data, system simulations are performed to identify the required specifications for IC implementation. This provides information such as optimal number of taps, fractionally-spaced tap delay, and tap coefficients for the proposed IC. With the obtained system requirements, IC building blocks are designed and fabricated in a 0.18- and #956;m CMOS technology. The fully-integrated reconfigurable CMOS equalizer provides a single-chip solution for compensating various band-limited channels. This enables 10-Gb/sec serial data transmission achieving signal integrity beyond their designed specifications.
223

Energy-Efficient Scalable Serial-Parallel Multiplication Architecture for Elliptic Curve Cryptosystem

Su, Chuan-Shen 25 July 2012 (has links)
In asymmetric cryptosystems, an important advantage of Elliptic Curve Cryptosystem (ECC) is the shorter key lengths than other cryptosystems. It can provide a level of security when the bit length over than 160 bits. So it has become a popular public key cryptographic system in recent year. Multiplier needs to run many times in scalar multiplication and it plays an essential role in ECC. Since the registers in multiplier are shifted every iteration, it will consume a lot of power in the computing process. So in this thesis, we propose five methods to save multiplication¡¦s energy consumption based on a scalable serial-parallel algorithm[1]. The first method is to design a low-power shift-register by modifying shift-register B to reduce the frequency of registers shifted. The second method is to use a frequency divider circuit. It can make registers to access a value every two clock cycles by modifying RA units. The third method is to introduce the gated clock circuit, and the clock signal of register will be disabled if its value is the same. The fourth method is to skip redundant operations and it can decrease the number of clock cycles for completing a multiplication operation. The last method raises multiplier¡¦s throughput by modifying RA units. The former three methods focus on low-power design, and the latter two methods emphasize on improving performance. Reducing power consumption and improving performance will save multiplication¡¦s energy consumption. Finally, we propose a Half Cycles schedule to raise scalar multiplication¡¦s performance. It is based on Montgomery scalar multiplication algorithm with projective coordinate[22][26]. For the hardware implementation, TSMC 0.13um library is employed and all modules are organized in a hierarchy structure. The implementation results show that the proposed multipliers have less energy consumption than traditional multiplier. It can get 5% ~ 24% energy saving. For Montgomery scalar multiplication, it can also reduce 12% ~ 47% energy consumption and is suitable for portable electronic products because its low area complexity and low energy.
224

Evaluation of Early Measures of Body Composition as Related to Beef Carcass Traits

Maulsby, Richard Paul. 2009 December 1900 (has links)
Two similarly managed trials were conducted to investigate serial ultrasound measures of body composition (longissimus muscle area (ULMA), 12th - rib fat thickness (UFAT), and percentage of intramuscular fat (UIMF)) early in the lives of feeder calves as they compared to carcass traits. Group 1 cattle were Charolais-sired by Brahman-British crossbred dams whereas Group 2 cattle were purebred Beefmaster. Both groups were fed at the same commercial feedlot (Graham Land and Cattle Co.) in Gonzales, Texas. In both data sets classifications were developed for ribeye area of Lower (less than 70.95 cm2, Middle (between 70.95 cm2 and 90.3 cm2) and Upper (over 90.3 cm2) based on a range that fit within the ribeye specifications of such branded beef programs as Certified Angus Beef and Nolan Ryan?s Tender Aged Beef. Differences among ribeye area and quality grade (Choice vs. Select) categories were evaluated for ultrasound and carcass traits. As reported previously, correlations between ultrasound measures and carcass traits became larger at times closer to harvest. In both sets of cattle, there were no differences in fat thickness or intramuscular fat at the ultrasound scan sessions or in these carcass traits due to ribeye area category. The same trend for quality grade classification was not seen across both groups of cattle however. In Group 1, there were no differences in early measures of body composition between carcass quality grade classes except for ultrasound fat thickness at weaning. However, in Group 2 cattle there were differences in ultrasound fat at times 1 and 2, IMF at time 1, and ribeye area at time 2 between cattle that graded choice verses those that graded select. Correlations between ultrasound measures of REA (r of .26 to .50) and ultrasound REA and carcass REA (r of .16 to .81) appeared to be lower in Group 1 vs. Group 2 (r of .55, and .64 to 81 respectively). Results from this project imply that changes in ribeye area will not automatically result in changes of marbling and vice versa. Furthermore, these results also show that ultrasound is useful to help predict beef carcass traits, but that early measures of body composition used alone do not explain a large portion of the variation in the carcass measures and specific methods should be developed by different biological cattle types.
225

Design of a MMIC serial to parallel converter in Gallium Arsenide. / Konstruktion av en MMIC serie-till-parallellomvandlare på Gallium Arsenid.

Nilsson, Tony, Samuelsson, Carl January 2001 (has links)
<p>A 5-bit MMIC serial to parallel converter has been designed in Gallium Arsenide. It is intended to be used together with a 5-bit True Time Delay (TTD) circuit, but it can easily be expanded into an arbitrary number of bits. The circuit has been designed with a logic style called DCFL and a 0.20 mm process (ED02AH) from OMMIC has been used to fabricate the circuit. The chip size of this 5-bit MMIC serial to parallel converter is 2.0x0.8 mm (including pads) and close to two hundred transistors are used. Due to the complexity of the transistor models the complete serial to parallel converter has not been fully simulated. However, the smaller building blocks like inverter, latch, etc. have been simulated successfully. These blocks were assembled into the complete circuit.</p>
226

A High Voltage Charge-Coupled Device (CCD) Controller ASIC for the Large Synoptic Survey Telescope (LSST)

Chun, Ross F 01 May 2010 (has links)
This thesis will present the design, implementation, and testing of a high voltage Charge-Coupled Device (CCD) controller ASIC for the Large Synoptic Survey Telescope (LSST), which will be used to study dark energy and dark matter. The LSST observatory, which includes a 3.2-gigapixel camera, will cover the entire sky every three nights by taking continuous 15-second exposures. The CCD controller ASIC, or Sensor Control Chip (SCC), will provide five CCD driver channels that are capable of generating serial or parallel clock signals for the LSST’s imaging sensors during readout mode. The SCC will also provide three programmable bias voltages for the CCDs along with eight supplementary programmable voltages and currents for the CCD’s output drain terminals. Additionally, the controller ASIC includes eight control signals for a separate Analog Signal Processing Integrated Circuit (ASPIC) that is designed as the readout chip for LSST. The SCC is designed to operate down to 153 K. Fabricated in a commercially available 0.8-micron Bipolar-CMOS-DMOS Silicon-On-Insulator (BCD-SOI) process, the SCC has been verified to meet all design requirements.
227

Blank Power: The Social and Political Criticism of Blank Fiction and Cinema

Donnelly, Ashley Minix 07 November 2008 (has links)
This dissertation explores a style of literature known as "blank" fiction that became popular in the United States in the mid-1980s, focusing on its stark, limited form, its minimal plots, its focus on commodification, and its scenes of graphic violence. The author presents the argument that filmmakers were producing pieces of cinema during the same time period that are similar in both form and content to the works of blank fiction. These films are a part of a style she labels "blank" cinema. Blank fiction and cinema are politically charged and highly critical of the social and political situation in America during the time in which they are produced. The authors and filmmakers producing blank works interrogate issues of social irresponsibility, rampant consumerism, and the global domination of capitalist values. Blank artists frequently criticize the perpetuation of such issues by the dominating power of white, middle- and upper-class men. The serial killer figure is used by many to represent the "unexamined" threat of those in power. The use of popular culture references and marketing tags are ubiquitous in blank fiction and film, and it is through the use of such signs that blank artists show their audiences that the power of those that traditionally control cultural ideologies in America can be manipulated and controlled by anyone, thus giving power to those who may have traditionally felt powerless and submissive to the dominant ideologies of American culture.
228

A method for the characterization of white spots in vacuum-arc remelted superalloys

Viosca, Alan Lee 30 July 2012 (has links)
Vacuum-Arc Remelting (VAR) is an important process for manufacturing Ti- and Ni-based superalloys. Currently, the sources and mechanisms behind microstructural anomalies produced in VAR superalloy ingots are not well understood. In order to help understand formation processes, a method of characterizing specific anomalies in VAR ingots is desired. This paper presents a method of characterizing the composition and morphology of anomalies in VAR alloy ingots using a combination of serial sectioning and X-ray fluorescence (XRF) energy dispersive spectroscopy (EDS) techniques. This process is demonstrated on a dirty white spot from an Alloy 718 sample. The white spot of interest was serial polished and 2-D XRF EDS maps were acquired at each polish depth. The EDS maps were then stacked to form a 3-D representation of the white spot. In addition, SEM and optical microscopy techniques were used to further characterize the composition and morphology of the dirty white spot. The dirty white spot is composed of both Ti-enriched and Nb-depleted regions. The 2-D EDS maps acquired with the XRF equipment provided adequate contrast for creating a 3-D representation of the Ti-rich region of the dirty white spot. However, contrast was not sufficient to create a 3-D representation of the Nb-depleted region. The XRF EDS equipment combined with SEM and optical microscopy techniques provided valuable information about the morphology and composition of the Alloy 718 dirty white spot. It is concluded that this dirty white spot was produced by fall-in from either the crown or shelf regions during the VAR process. / text
229

Requirements for effective collision detection on industrial serial manipulators

Schroeder, Kyle Anthony 16 October 2013 (has links)
Human-robot interaction (HRI) is the future of robotics. It is essential in the expanding markets, such as surgical, medical, and therapy robots. However, existing industrial systems can also benefit from safe and effective HRI. Many robots are now being fitted with joint torque sensors to enable effective human-robot collision detection. Many existing and off-the-shelf industrial robotic systems are not equipped with these sensors. This work presents and demonstrates a method for effective collision detection on a system with motor current feedback instead of joint torque sensors. The effectiveness of this system is also evaluated by simulating collisions with human hands and arms. Joint torques are estimated from the input motor currents. The joint friction and hysteresis losses are estimated for each joint of an SIA5D 7 Degree of Freedom (DOF) manipulator. The estimated joint torques are validated by comparing to joint torques predicted by the recursive application of Newton-Euler equations. During a pick and place motion, the estimation error in joint 2 is less than 10 Newton meters. Acceleration increased the estimation uncertainty resulting in estimation errors of 20 Newton meters over the entire workspace. When the manipulator makes contact with the environment or a human, the same technique can be used to estimate contact torques from motor current. Current-estimated contact torque is validated against the calculated torque due to a measured force. The error in contact force is less than 10 Newtons. Collision detection is demonstrated on the SIA5D using estimated joint torques. The effectiveness of the collision detection is explored through simulated collisions with the human hands and arms. Simulated collisions are performed both for a typical pick and place motion as well as trajectories that transverse the entire workspace. The simulated forces and pressures are compared to acceptable maximums for human hands and arms. During pick and place motions with vertical and lateral end effector motions at 10mm/s and 25mm/s, the maximum forces and pressures remained below acceptable levels. At and near singular configurations some collisions can be difficult to detect. Fortunately, these configurations are generally avoided for kinematic reasons. / text
230

Quasi-Orthogonal Frequency Division Multiple-Access for Serial Streaming Telemetry

Ponnaluri, Satya Prakash, Azimi-Sadjadi, Babak 10 1900 (has links)
ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / We propose a spectrally-efficient multiple-access technique that is particularly suitable for aeronautical telemetry applications involving serial streaming of data from multiple test articles to a ground station. Unlike conventional frequency-division multiple access, we assign overlapping frequency bands to different users with a minimum carrier separation corresponding to the symbol rate. We utilize multiuser detection strategies at the ground station to separate the transmissions from different test articles. As shown by the simulation results, the proposed scheme is robust to large frequency offsets due to oscillator offsets and Doppler shifts commonly encounters in aeronautical telemetry applications.

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