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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.
61

Impacts of midpoint FACTS controllers on the coordiantion between generator phase backup protection and generator capability limits

Elsamahy, Mohamed Salah Kamel 15 July 2011 (has links)
The thesis reports the results of comprehensive studies carried out to explore the impact of midpoint FACTS Controllers (STATCOM and SVC) on the generator distance phase backup protection in order to identify important issues that protection engineers need to consider when designing and setting a generator protection system. In addition, practical, feasible and simple solutions to mitigate the adverse impact of midpoint FACTS Controllers on the generator distance phase backup protection are explored. The results of these studies show that midpoint FACTS Controllers have an adverse effect on the generator distance phase backup protection. This adverse effect, which can be in the form of underreach, overreach or a time delay, varies according to the fault type, fault location and generator loading. Moreover, it has been found that the adverse effect of the midpoint FACTS Controllers extends to affect the coordination between the generator distance phase backup protection and the generator steady-state overexcited capability limit. The Support Vector Machines classification technique is proposed as a replacement for the existing generator distance phase backup protection relay in order to alleviate potential problems. It has been demonstrated that this technique is a very promising solution, as it is fast, reliable and has a high performance efficiency. This will result in enhancing the coordination between the generator phase backup protection and the generator steady-state overexcited capability limit in the presence of midpoint FACTS Controllers. The thesis also presents the results of investigations carried out to explore the impact of the generator distance phase backup protection relay on the generator overexcitation thermal capability. The results of these investigations reveal that with the relay settings according to the current standards, the generator is over-protected and the generator distance phase backup protection relay restricts the generator overexcitation thermal capability during system disturbances. This restriction does not allow the supply of the maximum reactive power of the generating unit during such events. The restriction on the generator overexcitation thermal capability caused by the generator distance phase backup protection relay highlights the necessity to revise the relay settings. The proposed solution in this thesis is to reduce the generator distance phase backup protection relay reach in order to provide secure performance during system disturbances.
62

Desorption of ammonia-water mixtures in microscale geometries for miniaturized absorption systems

Delahanty, Jared Carpenter 07 January 2016 (has links)
A study of ammonia-water desorption in compact counter-flow geometries was conducted. Two novel vapor generation units, comprising integrated desorber, analyzer, and rectifier segments that use microchannel geometries, were conceptualized. The branched-tray concept features a desorber segment that uses predominantly pool-boiling mechanisms for desorption, while the vertical column desorber relies on falling-film evaporation and boiling mechanisms. Both concepts rely on falling-film heat and mass transfer mechanisms in the analyzer and rectifier sections. Segmented heat and mass transfer models, based on available correlations and modeling methodologies, were developed and used for the design of branched tray and vertical column test sections. An experimental facility was designed and constructed to evaluate desorption and rectification heat and mass transfer processes within these components, under realistic operating conditions. Data were analyzed to determine the boiling/evaporation (desorber) and condensation (rectifier) heat transfer coefficients, and to determine values of the desorber liquid and vapor mass transfer coefficients. Additionally, high-speed video and images were used to gain insights into the hydrodynamic phenomena and heat transfer mechanisms in these vapor generation units. Results of the heat and mass transfer analysis were compared with the predictions of correlations and modeling methods in the literature. The vapor generation unit (VGU) test sections were evaluated across a range of concentrated solution mass fractions (0.400 – 0.550), desorber coupling-fluid inlet temperatures (170 – 190ᵒC), and concentrated solution flow rates (0.70 – 1.3 g s-1). Flow rates in this range correspond to desorber liquid Reynolds numbers of approximately 175 to 410 for the branched tray design, and desorber film Reynolds numbers of approximately 90 to 215 for the vertical column. Pressures observed within the VGU test sections ranged from approximately 1620 to 2840 kPa during testing. The novel VGUs were shown to achieve ideal cooling capacities as high as 432 and 323 W for the branched tray and vertical column, respectively. This parameter indicates the cooling capacity that would be achieved by an idealized cooling system using the refrigerant stream produced by the experimental VGU. Ideal COPs of 0.561 and 0.496 were demonstrated for the branched tray and vertical column, respectively. Experimental heat transfer coefficients were found to range from approximately 1860 to 11690 W m-2 K-1 for the pool-boiling desorption of the branched tray VGU. A new correlation was proposed and shown to provide good agreement with the data, achieving average and average absolute deviation of -5.2 and 16.1%, respectively, across the range of conditions tested. Falling-film evaporation/boiling heat transfer coefficients, determined for the desorption process in the vertical column VGU, were found to range from approximately 1290 to 4310 W m-2 K-1. Rectifier condensation heat transfer coefficients ranging from approximately 160 to 250 W m-2 K-1 were observed. Mass transfer coefficients for the desorbers of both concepts were also quantified. These results were used to develop revised heat and mass transfer models of the VGU concepts. The revised models were demonstrated to predict component-level performance with reasonable accuracy, and may be used in the design of future compact VGUs with similar geometries and operating conditions.
63

Simscape modeling of motor generator unit component for hybrid electric vehicle

Narkhede, Yashdeep 27 May 2016 (has links)
The thesis introduces the user to programming in Simscape language. A permanent magnet synchronous machine torque control drive system for hybrid electric vehicles has been analyzed, programmed, using Simscape language, and tested in this thesis. The thesis walks the reader through the process of creating custom components in Simscape language explaining details and syntax of the language at every step. Important excerpts of code for all the components designed, created and used in the process are explained in the thesis and the complete code for the same is provided in the Appendix. ix
64

Development of fast pneumatic system for the study of 14 MeV fission product yields

Montgomery, Matthew Taylor 02 October 2014 (has links)
The use of fission product yield data is pervasive among nuclear calculations, particularly in the realm of nuclear forensics and active interrogation for special nuclear material. The capital source of fission product yield data is the work of T.R. England and B.F. Rider, of Los Alamos National Laboratory, in the early 1990s. Though their work was certainly substantial, a great deal of data was generated computationally, in lieu of done empirically—particularly with low-yield, short-lived progeny. Due to this, relative uncertainties in the measurements can be as high as 64%, and vary wildly from database to database (oft times not even within one standard deviation of one another). The purpose of this work is to build a pneumatic system capable of cyclic irradiation coupled to a D-T neutron source, in order to cumulate proper counting statistics, by which one can backcalculate independent and cumulative fission yields. Beyond the design and control parameters of the pneumatic system, a precise flux characterization of the facility is presented, and finally, proof-of-concept is demonstrated by causing 14 MeV neutron-induced fission and identifying every observed fission product photopeak. / text
65

Design and Testing of a Corona Column and a Closed Gas Distribution System for a Tandem Van de Graaff Voltage Generator

Gray, Thomas Jack 06 1900 (has links)
The purpose of this study had been to design and test a corona column and an insulating gas distribution system for a small tandem Van de Graaff. The intent of this paper is to describe the gas handling system and to compare experimentally the effects of corona electrode shape on the corona current carried between adjacent sections of the column.
66

A Vacuum Tube for an Electrostatic Generator

Pool, John Reginald 08 1900 (has links)
The purpose of this study has been to construct two accelerating tubes with small beam apertures for the Van de Graaff, modifying the prototype tube designed and tested by Wiley (20), to design and construct a vacuum system for evacuating the tubes, and to determine the characteristics of the tube under operating conditions while installed in the generator.
67

Design and Analysis of Digital True Random Number Generator

Yadav, Avantika 31 October 2013 (has links)
Random number generator is a key component for strengthening and securing the confidentiality of electronic communications. Random number generators can be divided as either pseudo random number generators or true random number generators. A pseudo random number generator produces a stream of numbers that appears to be random but actually follow predefined sequence. A true random number generator produces a stream of unpredictable numbers that have no defined pattern. There has been growing interest to design true random number generator in past few years. Several Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC) based approaches have been used to generate random data that requires analog circuit. RNGs having analog circuits demand for more power and area. These factors weaken hardware analog circuit-based RNG systems relative to hardware completely digital-based RNGs systems. This thesis is focused on the design of completely digital true random number generator ASIC.
68

Generování a editace 2D terénu / Tools for generating and editing of 2D terrain

Mocný, Ondřej January 2011 (has links)
Unity is a game development tool with large userbase. One of the features it is missing, however, is a deeper support for the development of two dimensional games. In particular a tool for editing and generation of two dimensional terrain. The aim of the presented work is to design and develop this tool. First, the problem is analysed and a set of requirements is assembled. Then, the Unity development environment is described in order to be able to use it for implementing the tool. The tool is designed from the programmer's point of view and data representation inside Unity is proposed. Large part of the work is also devoted to describing different algorithms used for terrain generation. Finally, the user interface of the program is designed using the knowledge gained by studying Unity.
69

Kartläggning av spånproblem i GG8 : avdelning 9460 Volvo Aero Corporation

Andersson, Annika January 2002 (has links)
No description available.
70

Design of 1.6 Liter Genset Engine

Samarajeewa, Hasitha 08 August 2011 (has links)
Generators are widely used across the world as portable power units in case of power outages, used for emergency services and are also used in rural areas without access to electricity. The majority of commercially available generators use internal combustion engines designed as automobile engines with little or no optimization for use in generators. With operating conditions vastly different than that of automobile engines, they can be re-designed to operate much more efficiently as generator engines. The development objective here was to design a low cost, 1.6L, lean burn, internal combustion engine which minimizes heat losses, time losses and frictional losses to improve thermal efficiency. Various high swirl, high squish, easily CNC’d combustion chambers were created in the re-design process. A computer model was used to provide insight into the trade-off between time losses and heat losses. A maximum brake thermal efficiency of 37.2% was achieved.

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