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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

Advances in hollow core fibres and application to mid-infrared fibre gas lasers

Xu, Mengrong January 2018 (has links)
Anti-resonant hollow core fibre is a new kind of optical fibre waveguide in which light is trapped in a hollow core surrounded by the capillary formed microstructured cladding. This fibre exhibits high damage threshold, low dispersion and ultra-low nonlinearity with relatively low loss of a few tens of dB/km. Its intrinsic feature of multimode delivery limits the applications with high requirements of single mode transmission. In my thesis, I demonstrate how the design of hollow core fibre can be improved with single mode guidance. S2 imaging measurement was used to analyse the mode content of the solid core fibres. In my research, I established S2 measurement to measure the mode contents in hollow core fibres for the first time. Two hollow core fibres with 8 capillaries and 7 capillaries in their claddings were fabricated in same fashion and showed differences in low attenuations. By comparing the mode contents in both of the fibres via S2 imaging measurement, 7-capillary HCF was demonstrated to give better performance on single mode guidance. Among the applications of the HCF, the property of delivering high power in HCF makes the gas filled HCF laser possible. In my research, a continuous-wave mid-infrared acetylene filled hollow core laser was built with a slope efficiency of 33% and an output power of over 1 watt at the wavelength region of 3.1~3.2 μm. The pump source is an Erbium-doped fibre amplified tunable laser diode which works at C-band wavelength. The fibre without the gain medium has two transmission bands with low attenuation of 0.037 dB/m and 0.063 dB/m at pumping and lasing wavelengths respectively. This laser system works in either cavity-based configuration or single pass ASE configuration. The latter configuration shows a better performance in high output power and high slope efficiency. The optimized laser system was studied experimentally with the proper fibre length and gas pressure. This laser system could be extended to be filled with other molecules to longer wavelengths and has potential for high power output.
62

ESL Model of the Hyper-scalar Processor on a Chip

Chen, Po-kai 20 August 2007 (has links)
This paper proposed a scalable chip multiprocessor architecture, which is called Hyper-scalar combined with the concept of superscalar and multithreaded architecture; hence, this architecture can enhance single-threaded performance by using core group and also supports multithreaded applications. System programmer can dynamically allocate the core groups to accelerate a single thread by extended system instructions. In order to solve the data dependence between all issued instructions the virtual shared register file is proposed. This mechanism allows the data in local register files to be accessed from other cores through the data switching path hardware and the instructions are executed only when the operands are available. The instructions within a single-threaded application can be dispatched to variable cores without re-compilation. This execution paradigm accelerates the single-threaded performance more flexibly. In the case of simulation and experimental framework, the ESL Model written in SystemC, a modeling language based on C++ is to provide hardware-oriented simulation platform and the MediaBench suite is selected for the experiments. On average, the Hyper-scalar architecture can accelerate single-threaded performance by 30% to 110% using 2 ~ 8 cores.
63

Preliminary Study of Bypass Flow in Prismatic Core of Very High Temperature Reactor Using Small-Scale Model

Kanjanakijkasem, Worasit 1975- 14 March 2013 (has links)
Very high temperature reactor (VHTR) is one of the candidates for Generation IV reactor. It can be continuously operated with average core outlet temperature between 900°C and 950°C, so the core temperature is one of the key features in the design of VHTR. Bypass flow in the prismatic core of VHTR is not a designed feature but it is inevitable due to the combination of several causes and considerably affects the core temperature. Although bypass flow has been studied extensively, the current status of research on thermal/hydraulic core flow of VHTR is far from completion. Present study is the starting of bypass flow characteristic investigation using small-scale model that will fulfill understandings of bypass flow in the prismatic core of VHTR. Bypass flow experiments are conducted by using three small-scale models of prismatic blocks. They are stacked in a test section to form bypass gaps of single-layer blocks as exist in prismatic core of VHTR. Three bypass gap widths set in air and water flow experiments are 6.1, 4.4 and 2.7 mm. Experimental data shows that bypass flow fraction depends on bypass gap width and downstream condition of prismatic blocks, while pressure drop of flow through bypass gaps depends on bypass gap width only. Bypass flow simulations are performed by using STAR-CCM+ software after meshing parameters were determined from simulation exercises and grid independent study. Three turbulence models are employed in all bypass flow simulations which are stopped at physical time of 100 seconds marching by implicit unsteady scheme. Bypass flow fraction, coolant channel Reynolds number and bypass gap Reynolds number from air flow and water flow simulations with 6.1-mm bypass gap width are very close to experimental data. This is because bypass flow fractions from experiments at this bypass gap width are matched in construction of the simulation models. Discrepancies between results from simulations and experiments for remaining gaps increase when bypass gap width becomes smaller. Finally, guidelines for bypass flow experiments and simulations are drawn from the data in present study to improve bypass flow study in the future.
64

Core Self-Evaluations and the Hierarchical Model of Approach/Avoidance Motivation

Ferris, Douglas Lance January 2008 (has links)
In the current dissertation I examined the relation between a new personality trait, core self-evaluations (CSE), and job performance, using the hierarchical model of approach and avoidance motivation as a theoretical framework. The hierarchical model of approach and avoidance motivation proposes that the effects of distal personality traits on performance outcomes are mediated through mid-range approach and avoidance motivational mechanisms. However, some controversy exists surrounding whether CSE is best conceptualized as an antecedent of approach or avoidance motivation. As such, prior to examining the CSE-performance relation, I examined whether CSE is best conceptualized as an indicator of approach or avoidance temperament. In Study 1, using confirmatory factor analysis, I demonstrated that mean CSE scores loaded more strongly on a latent avoidance temperament factor than on a latent approach temperament factor. Study 2 provided further evidence for the avoidance nature of CSE by examining the relation between CSE and a motivational construct: achievement goal orientations. In particular, using structural equation modeling, CSE was negatively related to performance-approach, performance-avoid, and mastery-avoid achievement goal orientations, and unrelated to a mastery-approach goal orientation. Such a pattern of results is consistent with the relation between achievement goal orientations and other indicators of avoidance temperament. Having demonstrated that CSE is best conceptualized as an indicator of avoidance temperament, in Study 3 I used the hierarchical model of approach and avoidance motivation as a framework for examining the relation between CSE and job performance. The results indicated that the effect of CSE on job performance was mediated through avoidance, but not approach, goals. The results of the three studies are discussed in terms of their implications for the conceptualization of CSE. As well, the application of the hierarchical model of approach and avoidance motivation framework to organizational behavior is discussed.
65

Core Self-Evaluations and the Hierarchical Model of Approach/Avoidance Motivation

Ferris, Douglas Lance January 2008 (has links)
In the current dissertation I examined the relation between a new personality trait, core self-evaluations (CSE), and job performance, using the hierarchical model of approach and avoidance motivation as a theoretical framework. The hierarchical model of approach and avoidance motivation proposes that the effects of distal personality traits on performance outcomes are mediated through mid-range approach and avoidance motivational mechanisms. However, some controversy exists surrounding whether CSE is best conceptualized as an antecedent of approach or avoidance motivation. As such, prior to examining the CSE-performance relation, I examined whether CSE is best conceptualized as an indicator of approach or avoidance temperament. In Study 1, using confirmatory factor analysis, I demonstrated that mean CSE scores loaded more strongly on a latent avoidance temperament factor than on a latent approach temperament factor. Study 2 provided further evidence for the avoidance nature of CSE by examining the relation between CSE and a motivational construct: achievement goal orientations. In particular, using structural equation modeling, CSE was negatively related to performance-approach, performance-avoid, and mastery-avoid achievement goal orientations, and unrelated to a mastery-approach goal orientation. Such a pattern of results is consistent with the relation between achievement goal orientations and other indicators of avoidance temperament. Having demonstrated that CSE is best conceptualized as an indicator of avoidance temperament, in Study 3 I used the hierarchical model of approach and avoidance motivation as a framework for examining the relation between CSE and job performance. The results indicated that the effect of CSE on job performance was mediated through avoidance, but not approach, goals. The results of the three studies are discussed in terms of their implications for the conceptualization of CSE. As well, the application of the hierarchical model of approach and avoidance motivation framework to organizational behavior is discussed.
66

Performance Analysis of Graph Algorithms using Graphics Processing Units

Weng, Hui-Ze 02 September 2010 (has links)
The GPU significantly improves the computing power by increasing the number of cores in recent years. The design principle of GPU focuses on the parallism of data processing. Therefore, there is some limitation of GPU application for the better computing power. For example, the processing of highly dependent data could not be well-paralleled. Consequently, it could not take the advantage of the computing power improved by GPU. Most of researches in GPU have discussed the improvement of computing power. Therefore, we try to study the cost effectiveness by the comparison between GPU and Multi-Core CPU. By well-applying the different hardware architectures of GPU and Multi-Core CPU, we implement some typical algorithms, respectively, and show the experimental result. Furthermore, the analysis of cost effectiveness, including time and money spending, is also well discussed in this paper.
67

The study and analysis of how enterprises perform diversification by applying core competences -Case study T company

Chiang, Chun-Yen 12 July 2012 (has links)
Abstract The global outsourcing has becoming the sense from various industries; Taiwan is especially the one of ideal manufacturing base which manages production costs and with demonstrating dynamic strength from the world. However, while the branding companies from Europe and Japan still dominate innovation and technologies, sequentially consider to apply local material suppliers in developments and productions. Taiwan uses to be the competitive manufacturing place, the materials are usually nominated from developers, and thus the localization of the material manufacturing shall be the trend. The material manufacturers are required to pass through necessary certificates and production procedures to establish its own design technology and production bases. Therefore the capital of material manufactures uses to be fairly high compares to the other industries. Dining into such technology era, the investments of technical¡Bfinancial resources, plus combining the unpredictable economy¡Bconsumer requirements¡Binventory¡Bproperty usage making the material manufactures challenged ever. The listed company towards the permanent operation¡Brisk management¡Bfinancial managements, the managing levels need to review internal resources and apply its core competences to achieve the financial balancing¡Brisk control to make longer run business. The motivation of this research is to apply self -industrial experiences from the past and integrate associated literatures into one. Starting from an individual new business, lead the company to integrate internal resources and apply such competences to achieve diversification .This is the investigation of a studied company which demonstrates its core competences from the industry. Last to focus on the current and the new business in which to discuss and analyze below subjects:
68

The Strategy Research in Student Recruitment of Private Universities of Technology in Kaohsiung Area

Hsiang, Jia-chien 23 June 2004 (has links)
This research is to learn the recruitment strategy and the school advantages of private universities of technology in Kaohsiung. Two private universities of technology in Kaohsiung area were selected for this research. The questionnaire of school resource advantage cognition was designed for students selected from these two schools. Interviews with related administrative staff from these two schools were also proceeded for cross analysis and for verification of the statistic result. The core competence of the schools was demonstrated. The application, development, and accumulation of the core competence would then establish sustainable competitive advantages of the universities of technology. The following observations were obtained. 1.The advantages in geographic location and convenience in traffic do attract students. Schools in weak situations mostly put efforts on improving the life's mechanism and lift the expediency to the traffic in order to reduce the difference from their strong competitors. Land limitation can be adjusted by increasing the floor squares in the buildings. 2.The advantages in teacher quality owned by new universities of technology can not be caught up by their competitors within short period of time. To encourage the acquirements of the teacher¡¦s professional certificates and raise the academic research ability would be important in the future. 3.Most schools would develop courses on both theoretical and practical bases. But multi-degree system causes the difficulty in course design and complexity in administrative works. Therefore, simplification of the degree-system is a direction to advance. 4.Currently, career consultations are supported by database systems and some other electronic mechanism. To promote the employment opportunities for students, the cooperation between the school and the industry has significant effect and competent alumni in the industry can provide rich job information. Thus effective management to the precious alumnus resource is important. 5.The most significant competitive advantage of student recruitment is the school¡¦s reputation. It is worth establishing a specialized unit to integrate resources and develop marketing strategies for promoting the school¡¦s specializations. Keeping active relationships with the mass media to raise the reputation of the school is also essential. 6.The advertisement for recruitment of students should be initiative, creative and active and there should be sufficient fund, personnel and activities. Technological and vocational school fair is the best opportunity to show the distinguished features and raise the reputation of the school; therefore thorough planning to the fair is crucial.
69

The Exploration of Enterprises¡¦ Diversification Management Strategy ¡X A Case Study of M Company

Tsai, Chyi-Fa 06 July 2004 (has links)
In order to sustain their competitiveness, the enterprises usually conduct industrial reformation. For dispersing the risk of the enterprise, expanding their business scope and growth, or solving the perplexities in operation, the enterprises usually adopt diversified strategy. While operating, many aspects should be considered. Although diversification may make the enterprises grow, apply internal resources efficiently, reduce risks and increase more economic profits, however it could not guarantee the success after diversification as anticipated. When most enterprises proceed with diversification, the values they lose are much more than the ones they have created. This study mainly includes three aspects: enterprises¡¦ resources, diversified strategies and managerial strategies. By researches and surveys of literature domestic and foreign information, feasible proposal is recommended for reference of industries. This study also shows that the enterprises¡¦ diversification strategies must be combined with their core resources, so as to expand to relevant fields of their core businesses, and then even more they can expand to the neighborhood. Furthermore, the operating strategies can be adjusted to meet the industrial structure so that the enterprises can develop inexhaustibly. Hence, the easier way to succeed by relevant diversified method, and the following is vertically integration diversification. Although non-relevant diversification can help companies increase their profits, it also leads to the highest risks among the three diversified methods. Therefore, the enterprises should cautiously choose their development directions of new businesses. The research attempts to construct the dimensions of diversified management strategies built up is as below¡G I. Positioning of explicit diversification strategies. 1. When enterprises pursue growth by diversified measures, they have to have deployment of globalization. 2. The enterprises have to select suitable timing for diversification in order to reduce learning curves. II. Integration of enterprises¡¦ resources. 1. Integration of value chains. 2. The enterprises should cultivate innovative environment via integrated management of their internal resources. 3. Developing new core competence. III. Both techniques dispersions and markets expansion are necessary for operation strategies.
70

Design of the Execution-driven Simulation Environment for Hyper-scalar Architecture

Su, Ding-Siang 21 August 2008 (has links)
As a result of the microprocessor system research and the development of VLSI manufacturing process technology, the recent trend and development in high performance computer have toward to multi-core architecture. However current multi-core architectures are designed by the symmetric multi processors (SMP) concept. In traditional SMP mechanism, there are only data link between processor cores. So a single thread only can be handled by a single core, it limits the usage rate in multi-core and performance can not increase. This paper proposed a scalable chip multiprocessor architecture, which is called Hyper-scalar. The Principal characteristic of the architecture is ¡§design the interconnect control mechanisms for instructions in the multi-core¡¨. Some single scalar processor cores in Hyper-scalar architecture can be dynamically grouped as an n-way superscalar accelerator to improve the instruction-level parallelism, which is called accelerator group. Hyper-scalar combines the advantages of superscalar and multithreaded architecture; Hence, this architecture can not only enhance single-threaded performance by using accelerate group but also supports multithreaded applications. The paper based on ARM instruction set, to analyze how to create the interactive control mechanisms for instruction in the multi-core, and how to enhance the performance of a single thread in the Hyper-scalar architecture. It can be divided into four parts: register flow, memory flow, instruction control flow, chop of multi cycle instruction. When instructions are issued into the processor, they must be attached dependence tags that can solve the dependence between all issued instructions. All instructions can exchange the data through the virtual shared register file (VSRF) mechanism, and all instructions are executed only when the operands are available. In the memory flow part: we solve the dependence problem with a simple technique¡Xto execute instruction in instruction order. In instruction control flow part: in order to improve performance, we perform speculation execution mechanism, so the instructions can out of order execution beyond the basic block. Finally because there are some multi cycle instructions in the ARM instruction set, in hyper-scalar framework can chop into many one cycle instructions to further enhance performance. The simulation Model is written by SystemC, a modeling language based on C++ is to provide hardware-oriented simulation platform and the MediaBench suite is selected for the experiments. On average, the Hyper-scalar architecture can accelerate single-threaded performance by 50% to 300% using 2 ~ 8 cores.

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