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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.
331

Strategies for Incident Management in an Urban Street Network

Bhide, Vikramaditya 31 March 2005 (has links)
In this research the problem of incident congestion on surface street networks is addressed. Microscopic simulation is used to simulate incident scenarios on various corridors in the Tampa Bay area. The effect of the three factors, namely, network, speed and signal strategies on the traffic flow is studied. The network performance is based on Highway Capacity Manual specified measures of effectiveness prepared by the Transportation Research Board. Three inherently different city corridors, high, medium and low volume, are used to test the strategies developed. The strategies investigated include varying speed limits during incidents and using pre-timed and semi-actuated signals that respond to real time traffic volumes. The effectiveness measures are total delay in vehicle minutes, average speed in miles per hour and average travel time in seconds. Different facilities on a network include intersections; both signalized and unsignalized, local highways and arterials. The outputs from the simulation model is used to set up a factorial design to study the interaction between network type, signal strategy and speed strategy with the measures of effectiveness being the response variables. This type of corridor analysis is unique and provides decision support for local transportation planning departments for making corridor enhancements. In most city, state or county planning departments road planning is merely based on projected traffic demand using existing static models and does not factor necessary adjustments for incidents. Another unique aspect of this research is that variable speed limits are tested on surface streets. Such a test is not available in the literature. With dynamic message signs, next generation communication networks for traffic signal control and ITS technologies available, it is possible to implement the strategies suggested in this research.
332

Consumable Process Development for Chemical Mechanical Planarization of Bit Patterned Media for Magnetic Storage Fabrication

Bonivel, Joseph T., Jr. 25 October 2010 (has links)
As the superparamagnetic limit is reached, the magnetic storage industry looks to circumvent the barrier by implementing patterned media (PM) as a viable means to store and access data. Chemical mechanical polishing (CMP) is a semiconductor fabrication technique used to planarize surfaces and is investigated as a method to ensure that the PM is polished to surface roughness parameters that allow the magnetic read/write head to move seamlessly across the PM. Results from this research have implications in feasibility studies of utilizing CMP as the main planarization technique for PM fabrication. Benchmark data on the output parameters of the CMP process, for bit patterned media (BPM), based on the machine process parameters, pad properties, and slurry characteristics are optimized. The research was conducted in a systematic manner in which the optimized parameters for each phase are utilized in future phases. The optimum results from each of the phases provide an overall optimum characterization for BPM CMP. Results on the CMP machine input parameters indicate that for optimal surface roughness and material removal, low polish pressures and high velocities should be used on the BPM. Pad characteristics were monitored by non destructive technique and results indicate much faster deterioration of all pad characteristics versus polish time of BPM when compared to IC CMP. The optimum pad for PM polishing was the IC 1400 dual layer Suba V pad with a shore hardness of 57, and a k-groove pattern. The final phase of polishing evaluated the slurry polishing properties and novel nanodiamond (ND) slurry was created and benchmarked on BPM. The resulting CMP output parameters were monitored and neither the ND slurry nor the thermally responsive polymer slurry performed better than the commercially available Cabot iCue slurry for MRR or surface roughness. Research results indicate CMP is a feasible planarization technique for PM fabrication, but successful implementation of CMP for planarizing PM must address the high initial start up cost, increase in the number of replacement pads, and increase in polishing time to reach the required surface roughness for magnetic storage devices.
333

Cognitive radios : fundamental limits and applications to cellular and wireless local networks / Fundamental limits and applications to cellular and wireless local networks

Chung, Goochul 12 July 2012 (has links)
An ever increasing number of wirelessly-enabled applications places a very high demand on stringent spectral resources. Cognitive radios have the potential of enhancing spectral efficiency by improving the usage of channels that are already licensed for a specific purpose. Research on cognitive radios involves answering questions such as: how can a cognitive radio transmit at a high data rate while maintaining the same quality of service for the licensed user? There are multiple forms of cognition studied in literature, and each of these models must be studied in detail to understand its impact on the overall system performance. Specifically, the information-theoretic capacity of such systems is of great interest. Also, the design of cognitive radio is necessary to achieve those capacities in real applications. In this dissertation, we formulate different problems that relate to the performance of such systems and methods to increase their efficiency. This dissertation discusses, firstly, the means of "sensing" in cognitive systems, secondly, the optimal resource allocation algorithms for interweave cognitive radio, and finally, the fundamental limits of partially and overly cognitive overlay systems. / text
334

Computational applications of invariance principles

Meka, Raghu Vardhan Reddy 14 August 2015 (has links)
This thesis focuses on applications of classical tools from probability theory and convex analysis such as limit theorems to problems in theoretical computer science, specifically to pseudorandomness and learning theory. At first look, limit theorems, pseudorandomness and learning theory appear to be disparate subjects. However, as it has now become apparent, there's a strong connection between these questions through a third more abstract question: what do random objects look like. This connection is best illustrated by the study of the spectrum of Boolean functions which directly or indirectly played an important role in a plethora of results in complexity theory. The current thesis aims to take this program further by drawing on a variety of fundamental tools, both classical and new, in probability theory and analytic geometry. Our research contributions broadly fall into three categories. Probability Theory: The central limit theorem is one of the most important results in all of probability and richly studied topic. Motivated by questions in pseudorandomness and learning theory we obtain two new limit theorems or invariance principles. The proofs of these new results in probability, of interest on their own, have a computer science flavor and fall under the niche category of techniques from theoretical computer science with applications in pure mathematics. Pseudorandomness: Derandomizing natural complexity classes is a fundamental problem in complexity theory, with several applications outside complexity theory. Our work addresses such derandomization questions for natural and basic geometric concept classes such as halfspaces, polynomial threshold functions (PTFs) and polytopes. We develop a reasonably generic framework for obtaining pseudorandom generators (PRGs) from invariance principles and suitably apply the framework to old and new invariance principles to obtain the best known PRGs for these complexity classes. Learning Theory: Learning theory aims to understand what functions can be learned efficiently from examples. As developed in the seminal work of Linial, Mansour and Nisan (1994) and strengthened by several follow-up works, we now know strong connections between learning a class of functions and how sensitive to noise, as quantified by average sensitivity and noise sensitivity, the functions are. Besides their applications in learning, bounding the average and noise sensitivity has applications in hardness of approximation, voting theory, quantum computing and more. Here we address the question of bounding the sensitivity of polynomial threshold functions and intersections of halfspaces and obtain the best known results for these concept classes.
335

Evaluation of Herbicides as Desiccants for Lentil (Lens culinaris Medik) Production

2015 August 1900 (has links)
The indeterminate nature of lentil (Lens culinaris Medik), in conjunction with adverse field conditions, can lead to varying degrees of maturity among plants at harvest. This variable maturity may have a negative influence on lentil production and can delay harvest. Desiccants are currently used to improve lentil crop dry-down. However, applying desiccants too early may result in reduced crop yield and quality, and also leave unacceptable herbicide residues in lentil seeds. In addition, only four herbicides (glyphosate, diquat, saflufenacil, and glufosinate) are registered as desiccants for lentil desiccation in Canada, which limits options for growers. Therefore, the objectives of this thesis were i) to determine the importance of desiccant application timing in affecting crop yield and quality, as well as herbicide residues and ii) to determine whether additional desiccants applied alone or tank-mixed with glyphosate provide better crop desiccation. Field trials were conducted at Saskatoon and Scott, Saskatchewan, from 2012 to 2014. In the application timing trial, glyphosate or saflufenacil alone, or glyphosate+saflufenacil generally decreased seed yield, thousand seed weight, and crop dry-down, and increased herbicide residue levels at earlier application timings. For example, when applied at 60% seed moisture, saflufenacil reduced yield and thousand seed weight by 22% and 10%, respectively, and resulted in glyphosate and saflufenacil residues greater than 2.0 and 0.03 ppm, respectively. Although there were no reductions in yield and thousand seed weight when desiccants were applied at 50% or 40% seed moisture, glyphosate residue exceeded 2.0 ppm. Application of desiccants at 20 or 30% seed moisture content had no effect on yield, thousand seed weight, or herbicide residues. These results indicate that desiccant application timing is critical, and should not be made before 30% seed moisture. In a second study, glufosinate and diquat tank mixed with glyphosate were the most consistent desiccants and provided optimal crop dry-down without reducing yield and thousand seed weight, and effectively reduced glyphosate residue. The other herbicides tested (pyraflufen-ethyl and flumioxazin) were found to be poor options for growers as they had sub-optimal crop desiccation and did not affect glyphosate residue.
336

Renormalization and central limit theorem for critical dynamical systems with weak external random noise

Díaz Espinosa, Oliver Rodolfo 28 August 2008 (has links)
Not available / text
337

Advances in Non-Foster Circuit Augmented, Broad Bandwidth, Metamaterial-Inspired, Electrically Small Antennas

Zhu, Ning 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 / There are always some intrinsic tradeoffs among the performance characteristics: radiation efficiency, directivity, and bandwidth, of electrically small antennas (ESAs). A non-Foster enhanced, broad bandwidth, metamaterial-inspired, electrically small, Egyptian axe dipole (EAD) antenna has been successfully designed and measured to overcome two of these restrictions. By incorporating a non-Foster circuit internally in the near-field resonant parasitic (NFRP) element, the bandwidth of the resulting electrically small antenna was enhanced significantly. The measured results show that the 10 dB bandwidth (BW10dB) of the non-Foster circuit-augmented EAD antenna is more than 6 times the original BW10dB value of the corresponding passive EAD antenna.
338

Experter i revisionsprocessen : Hur upplever revisorn att revisionskvaliteten påverkas? / Experts in the audit process : How does the auditor experience the influence on audit quality?

Forsman, Madeleine, Wiström, Kristin January 2015 (has links)
Bakgrund och problem: Revisorer har blivit beroende av experter i sitt arbete på grund av den komplexitet som har uppstått kring både redovisningen och revisionen. Det är revisorn som bestämmer när en expert ska involveras och hur stor påverkan expertens arbete får på revisionen. Samtidigt är revisorns uppgift att leverera kvalitetssäker information till intressenter och det är revisorn som avgör när tillräcklig revisionskvalitet har uppnåtts. Frågan är då hur revisorn upplever att revisionskvaliteten påverkas när experter används. Syfte: Syftet med studien är att förklara hur revisorer upplever att revisionskvaliteten påverkas när experter används. Metod: Studien har i huvudsak en kvantitativ metod där enkäter har skickats ut till revisorer för att få svar på studiens syfte. För att få en djupare förståelse för experternas arbete har en kvalitativ förstudie med intervjuer genomförts. Slutsats: Vårt resultat indikerar på att revisorer upplever att revisionskvaliteten blir högre när experter används i revisionen. Resultatet från vår första regressionsmodell tyder på att när experter får mer handlingsutrymme/inflytande upplever revisorer att revisionskvaliteten blir högre. Revisionskvaliteten påverkas också svagt av i vilken omfattning revisorer tar hjälp av experter. Revisorer som tar hjälp av experter i större omfattning upplever att revisionskvaliteten blir högre. Resultatet från vår andra regressionsmodell tyder på att det enbart är expertens inflytande som leder till högre revisionskvalitet. Vårt resultat indikerar på att det enligt revisorer är värt att lägga tid och resurser på experter då de bidrar till högre revisionskvalitet. / Background and Problem: Accountants have become dependent with using experts in theirwork because of the complexity that has occurred around both accountingand auditing. It is the auditor that decides when an expertshould be included and how great of impact the experts work willhave on the audit. Meanwhile the auditor’s duty is to deliver qualityassured information to stakeholders and it is the auditor that willdecide when adequate audit quality is achieved. The question ishow the auditor experiences the influence on audit quality whenthey include experts in their work? Purpose: The purpose of the study is to explain how the auditors experiencethe influence on audit quality when they include experts in theirwork. Method: This study has mainly a quantitative method where surveys havebeen sent to auditors to obtain answers to the study’s purpose. Toget a deeper understanding of the experts work has a qualitativefeasibility study with interviews been conducted. Conclusion: Our results indicate that auditors feel that audit quality will behigher when the experts are used in the audit. The results from ourfirst regression model suggests that when the experts get moreleeway/influence auditors experience that audit the quality will behigher. Audit quality is also affected slightly by the extent towhich auditors are taking the help of experts. Accountants whotake the help of experts to a greater extent perceive that auditquality will be higher. The result from our second regression modelindicates that it’s only the expert's influence that leads to higheraudit quality. Our results indicate that, according to auditors isworth spending time and resources on experts when they contributeto higher quality audits.
339

Expanded forming limit testing for sheet forming processes

Shouler, Daniel Reginald January 2011 (has links)
No description available.
340

Nonlinear aeroelastic analysis of aircraft wing-with-store configurations

Kim, Kiun 30 September 2004 (has links)
The author examines nonlinear aeroelastic responses of air vehicle systems. Herein, the governing equations for a cantilevered configuration are developed and the methods of analysis are explored. Based on the developed nonlinear bending-bending-torsion equations, internal resonance, which is possible in future air vehicles, and the possible cause of limit cycle oscillations of aircraft wings with stores are investigated. The nonlinear equations have three types of nonlinearities caused by wing flexibility, store geometry and aerodynamic stall, and retain up to third-order nonlinear terms. The internal resonance conditions are examined by the Method of Multiple Scales and demonstrated by time simulations. The effect of velocity change for various physical parameters and stiffness ratio is investigated through bifurcation diagrams derived from Poinar´e maps. The dominant factor causing limit cycle oscillations is the stiffness ratio between in-plane and out-of-plane motion.

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