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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.
101

Multiple Injector Concepts for Compression Ignition Engines - Experimental and computational work for lower heat losses, increased efficiency and improved combustion control

Nyrenstedt, Gustav 05 1900 (has links)
Several modern marine engines use multiple injectors for lower heat losses and higher efficiency. However, the heavy-duty vehicles still apply a single injector per cylinder. This work investigates how multiple injectors can be operated in compression ignition heavy-duty engines along with potential benefits from such concepts. The studies aimed to avoid high boundary gas temperatures by having two injectors at the rim of the bowl, in addition to the standard injector. A longer injector-wall distance reduces the amount of hot gases at the boundaries for reduced convective heat losses. Additional degrees of freedom also follows from an increased number of injectors to simplify combustion control. The thesis included CFD simulations, metal engine experiments, and optical engine diagnostics to investigate the efficiency –and emission benefits for two –and three-injector concepts compared to the single-injector approach. The CFD simulations aimed to set beneficial spray angles and chamber geometries for reduced heat losses and reasonable emission levels with and without swirl at different load conditions. A flat bowl with two injectors reduced the heat losses by 4.2 %-points resulting in a direct efficiency increase of 1.9 %-points at middle-load conditions. Metal engine studies confirmed the simulation results by testing two -and three-injector concepts. The higher three-injector flow rate raised efficiency and diminished heat losses while providing low nitric oxide levels. Thus, three injectors lessen the typical trade-off between efficiency and nitric oxides. The thesis further performed single-injector optical engine experiments to investigate combustion control limitations. The results concluded that high soot levels occur from the multiple injections used to achieve isobaric combustion. These high soot levels followed by injecting into fuel-rich zones, which can be avoided by using multiple injectors. Finally, the thesis provides a multiple injector design suitable for heavy-duty production engines.
102

Multi-Class Vocation Identification for Heavy Duty Vehicles

Yadav, Varun 12 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Understanding the operating profile of different heavy-duty vehicles is needed by parts manufacturers for improved configuration and better future design of the parts. This study investigates the use of a tournament classification approach for both vocation and fleet identi- fication. The proposed approach is implemented using four different classification techniques, namely, K-Means, Expectation Maximization, Particle Swarm Optimization, and Support Vector Machines. Vocations classifiers are developed and tested for six different vocations ranging from coach buses to rail inspection vehicles. Operational field data are obtained from a number of vehicles for each vocation and aggregated over a pre-set distance that varies according to the data collection rate. In addition, fleet classifiers are implemented for five fleets from the coach bus vocation using a similar approach. The results indicate that both vocation and fleet identification are possible with a high level of accuracy. The macro average precision and recall of the SVM vocation classifier are approximately 85%. This result was achieved despite the fact that each vocation consisted of multiple fleets. The macro average precision and recall of the coach bus fleet classifier are approximately 77% even though some fleets had similar operating profiles. These results suggest that the proposed classifier can help support vocation and fleet identification in practice.
103

A framework for wealth transfer taxation in South Africa

Muller, Elzette 09 October 2010 (has links)
The South African tax system currently provides for wealth transfer taxation by virtue of estate duty in terms of the Estate Duty Act and donations tax in terms of Part V of the Income Tax Act, which are primarily levied on the transferor. At the outset, this study investigates the conceptual justification for this type of taxation in the South African context, especially in view of the fact that some countries have recently abolished their wealth transfer taxes. It is concluded that the arguments against wealth transfer taxation are not compelling enough to justify its abolition from the South African tax system. It is also submitted that the levying of capital gains tax on the death of a wealth holder cannot act as a substitute measure to tax wealth transfers in the South African system. It is, however, explained that the levying of both taxes reflects a scenario of double taxation on a deceased estate and that the equity criterion supports the taxation of wealth transfers in the hands of the recipient. The possibility of merely including inheritances and gifts in the “gross income” of a beneficiary is explored, but is submitted that such a move would be politically and administratively unlikely. After having come to the conclusion that wealth transfer taxation is indeed justifiable for the South African tax system, two key issues are explored in the study. The first issue relates to the lack of integration that exists between the taxation of inter vivos transfers (under the donations tax regime) and the taxation of transfers on death (under the estate duty regime). After having compared the systems in the United Kingdom, the Netherlands and Ireland, it is concluded that it is conducive to equity, neutrality and tax administration that the rules relating to the jurisdictional basis, double taxation relief, tax rates and valuation rules apply (in general) equally to inter vivos transfers and transfers on death. It is evident, however, that it remains necessary to distinguish between the two types of transfers, because this creates a flexible platform to accommodate special circumstances and differences. A number of measures to improve integration under the current regimes are recommended, but it is suggested that, ideally, the Estate Duty Act and Part V of the income Tax Act should be replaced by a single integrated statute. The second issue deals with the question whether or not the well-established estate duty and donations tax regimes should be replaced by a recipient-based system, especially in view of its theoretical appeal. After having shown that a recipient-based wealth transfer tax offers more appropriate solutions to some of the problem areas common to wealth transfer taxation in general (such as the accommodation of third-party life insurance benefits, limited interests and a special regime for discretionary trusts), it is concluded that the current regimes should be replace by a recipient-based wealth transfer tax, which may even be accommodated as a separate schedule to the existing income Tax Act in much the same way as capital gains tax. / Thesis (LLD)--University of Pretoria, 2010. / Mercantile Law / unrestricted
104

Evaluation and Comparison of MAC Protocols in Wireless Sensor Networks

Kollipara, Sharmila 22 December 2010 (has links)
No description available.
105

The effects of fuels and test cycles on light-duty vehicle exhaust emissions

Kelly, Kenneth John January 1998 (has links)
No description available.
106

Duty-Cycled Wireless Sensor Networks: Wakeup Scheduling, Routing, and Broadcasting

Lai, Shouwen 06 May 2010 (has links)
In order to save energy consumption in idle states, low duty-cycled operation is widely used in Wireless Sensor Networks (WSNs), where each node periodically switches between sleeping mode and awake mode. Although efficient toward saving energy, duty-cycling causes many challenges, such as difficulty in neighbor discovery due to asynchronous wakeup/sleep scheduling, time-varying transmission latencies due to varying neighbor discovery latencies, and difficulty on multihop broadcasting due to non-simultaneous wakeup in neighborhood. This dissertation focuses on this problem space. Specifically, we focus on three co-related problems in duty-cycled WSNs: wakeup scheduling, routing and broadcasting. We propose an asynchronous quorum-based wakeup scheduling scheme, which optimizes heterogenous energy saving ratio and achieves bounded neighbor discovery latency, without requiring time synchronization. Our solution is based on quorum system design. We propose two designs: cyclic quorum system pair (cqs-pair) and grid quorum system pair (gqs-pair). We also present fast offline construction algorithms for such designs. Our analytical and experimental results show that cqs-pair and gqs-pair achieve better trade-off between the average discovery delay and energy consumption ratio. We also study asymmetric quorum-based wakeup scheduling for two-tiered network topologies for further improving energy efficiency. Heterogenous duty-cycling causes transmission latencies to be time-varying. Hence, the routing problem becomes more complex when the time domain must be considered for data delivery in duty-cycled WSNs. We formulate the routing problem as time-dependent Bellman-Ford problem, and use vector representation for time-varying link costs and end-to-end (E2E) distances. We present efficient algorithms for route construction and maintenance, which have bounded time and message complexities in the worst case by ameliorating with beta-synchronizer. Multihop broadcast is complex in duty-cycled WSNs due to non simultaneous wakeup in neighborhoods. We present Hybrid-cast, an asynchronous multihop broadcast protocol, which can be applied to low duty-cycling or quorum-based duty-cycling schedules, where nodes send out a beacon message at the beginning of wakeup slots. Hybrid-cast achieves better tradeoff between broadcast latency and broadcast count compared to previous broadcast solutions. It adopts opportunistic data delivery in order to reduce the broadcast latency. Meanwhile, it reduces redundant transmission via delivery deferring and online forwarder selection. We analytically establish the upper bound of broadcast count and the broadcast latency under Hybrid-cast. To verify the feasibility, effectiveness, and performance of our solutions for asynchronous wakeup scheduling, we developed a prototype implementation using Telosb and TinyOS 2.0 WSN platforms. We integrated our algorithms with the existing protocol stack in TinyOS, and compared them with the CSMA mechanism. Our implementation measurements illustrate the feasibility, performance trade-off, and effectiveness of the proposed solutions for low duty-cycled WSNs. / Ph. D.
107

Povinnost loajality společníka v obchodní společnosti / The Duty of Loyalty of a Member of a Business Company

Polena, Stanislav January 2012 (has links)
The duty of loyalty of a member of a business company This thesis deals with the topic closely connected with the field of corporate governance which is a part of corporate law. According to the American legal theory is duty of loyalty one of the fiduciary duties. The traditional classification of fiduciary duties is based on dualism - duty of loyalty and duty of care. But this concept is changing over time mainly due to case law. There is no settled opinion on the basic question how many fiduciary duties there are. Current opinion of the respected authority in this field - Delaware' Supreme Court is based on dualism of fiduciary duties, but not in the traditional meaning. The duty of loyalty includes according to the opinion of the judges not only conflicts of interests and self-dealing situations, but breach of good faith as well. On the other hand the traditional point of view was settled on two fiduciary duties - loyalty and care as well. Duty of loyalty was connected with conflicts of interest situations between principal and agent, when the personal financial interest of the agent was present. Duty of loyalty protected the legal position of the principal when agent managed entrusted property. The duty of care was connected with the interest of the principal and due performance of the agent with the...
108

A qualitative examination of the administrative process of fleet enlisted personnel in various medical categories

Weatherford, Lenora B. P. 03 1900 (has links)
Approved for public release; distribution is unlimited. / The purpose of this research is to examine the medical management process of placing and monitoring active duty fleet enlisted personnel in a temporary medical duty status and its impact on fleet readiness. Due to the variety of medical categories this research focuses primarily on personnel placed in Temporary Limited Duty and Medical Hold. Personnel in medical status "limbo" decrease readiness and cost the Navy millions of personnel dollars each year. The study highlights improvements in communication, education and training at all levels of the organization based on observations from the fleet and medical communities. This research is intended to provide stakeholders with a matrix for decision-making and provide guidance on the various temporary medical status categories and recommends design changes to the current Temporary Limited Duty Process. / Lieutenant, Medical Service Corps
109

Základní povinnosti členů představenstva s důrazem na povinnost loajality / General duties of directors, in particular duty of loyalty

Mancelová, Silvia January 2015 (has links)
The dissertation is focused on research of the general duties of members of the board of directors in a capital company, in particular the duty of loyalty. Besides the duty of loyalty, members of the board of directors have a duty to act with due managerial care. The doctrine paid attention to the specification of the duty to act with due managerial care but there has, as yet, been no attention paid to the duty of loyalty. The new legislation contained in the Civil Code Act n. 89/2012 Sb. (CC) subordinates the duty of loyalty under the duty to act with due managerial care. The subject of the dissertation is research of the nature, origin, and function, of the duty of loyalty. The conclusion of the dissertation is the confirmation of the hypothesis, that the duty of loyalty by which a member of the board of directors is bound, is a fiduciary duty and an independent duty, which is not a part of the duty to act with due managerial care.
110

Povinnost mlčenlivosti zaměstnance v základním pracovněprávním vztahu / An Employee's Duty of Confidentiality in a Basic Labour Relationship

Brodská, Hana January 2018 (has links)
This diploma thesis deals with the topic of an employee's duty of confidentiality in a basic labour relationship. It seeks to find an answer to the question of whether there is some kind of a "general" employee's duty of confidentiality of certain facts, to which all the employees must oblige. The Czech Labour Code does not explicitly define this duty. If a general duty does not exist, it would have to be stipulated contractually. This diploma thesis is divided into four parts. The first part pays attention to the duty of confidentiality as such. It focuses on its content because it is essential to clarify what the "duty of confidentiality" means. Definitions of the duty of confidentiality created by different expert literature authors are covered in this part including the definition created by the author of this thesis. The second part represents the core of this diploma thesis since it deals with an employee's duty of confidentiality as it is stipulated by the Labour Code. The author addresses the so-called "special" duties of confidentiality which are explicitly stated in the Labour Code for certain groups of employees. Moreover, this part examines the general duty of confidentiality applicable to all employees who carry out work based on a concluded basic labour relationship. An employee's...

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