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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.
201

Conceptual design for a re-entrant type fuel channel for supercritical water-cooled nuclear reactors

Samuel, Jeffrey 01 April 2011 (has links)
Current CANDU-type nuclear reactors use a once-through fuel-channel with an annulus gas insulating it from the moderator. The current reference design for a CANDU-type SuperCritical Water-Cooled Reactor (SCWR) is to eliminate the annulus gap and use a ceramic insert to insulate the coolant from the moderator. While such a design may work, alternative fuel-channel design concepts are under development to explore the optimum efficiency of SCWRs. One such alternative approach is called the Re-Entrant fuel-channel. The Re-Entrant fuel-channel consists of three tubes, the inner tube (flow tube), pressure tube and an outer tube. The fuel bundles are placed in the inner tube. An annulus is formed between the flow and pressure tubes, through which the primary coolant flows. A ceramic insulator is placed between the pressure tube and the outer tube. The coolant flows through the annulus receiving heat from the inner tube from one end of the channel to another. At the far end, the flow will reverse direction and enter the inner tube, and hence the fuel-string. At the inlet, the temperature is 350°C for a high-pressure coolant (pressure of 25 MPa), which is just below the pseudocritical point. At the outlet, the temperature is about 625ºC at the same pressure (the pressure drop is small and can be neglected). The objective of this work was to design the Re-Entrant channel and to estimate the heat loss to the moderator for the proposed new fuel-channel design. A numerical model was developed and MATLAB was used to calculate the heat loss from the insulated Re-Entrant fuel-channel along with the temperature profiles and the heat transfer coefficients for a given set of flow, pressure, temperature and power boundary conditions. Thermophysical properties were obtained from NIST REFPROP software. With the results from the numerical model, the design of the Re-Entrant fuelchannel was optimized to improve its efficiency / UOIT
202

End of life scenarios for the Re-load pallets-how different waste scenarios impacts the life cycle environmental impact comparison with other pallet type

Ali, Azhar January 2011 (has links)
Increasing consumption and transportation gears the use of transport utilities which cause environmental effects over the globe. Environmental performance of three different types of pallets such as Re-load, plastic and corrugated fibreboard pallets are evaluated in this project. LCA tool is used to assess and compare their environmental performance in all phase of their life cycle but more focusing on end of life phase.   This study gives more emphasis to waste treatment options such as incineration, landfilling and recycling. Three different end of life scenarios have been used in this study such as 100% incineration, 100% landfilling and 100% recycling.   This study includes results of all the phases of all three types of pallets which are analysed in this report. More detailed results could be seen in excel sheets. Results of impact analysis tells that landfilling contributes to 14793 Kg CO2 of global warming potential in case of corrugated pallets. Incineration contributes to 12148.6 Kg CO2 of global warming potential. Recycling contributes to 7136 Kg CO2 of global warming. Re-load pallets show the major contribution of global warming is from landfilling approx 813.2 Kg CO2 of global warming potential. Recycling and incineration contribute to 438 Kg CO2 and 726.7 Kg CO2 of global warming potential respectively. In plastic case incineration contributes the most to global warming approximate 1183.8 Kg CO2 of global warming potential. Landfilling and recycling contribute almost the same approximate 932.6 Kg CO2 of global warming potential and 924.5 Kg CO2 of global warming potential respectively. Acidification impact show corrugated pallets cause high emissions when they are treat with landfilling and give negative values of incineration. In Eutriphication impact corrugated pallets are considered better in a sence they are inbetween 150 and 100 kg of PO-4. Re-load pallets give the least values when they are applied to different end of life scenarios.   According to the results recycling could be replace other waste treatment options because of less impact through out the end of life. Secondly, Reload pallets represent a environmental friendly product which can be improved more after this study. Lack of LCI data is the major problem in this study because it is not easily accessible and it is very time consuming part of this study. Results might be different if more data is available.   This study can be helpful for further study, for instance more replaceable scenarios will show different results for all three types of pallets. Moreover, it helps to compare more pallet types which are already in the market or propose to come in the market.
203

To explore the policy influence of cable TV franchise combination

shiao, shiao-chun 03 September 2004 (has links)
Abstract The main purpose of this article is to explore the policy influence of cable TV franchise combination. In order to break the local monopoly of Taiwan¡¦s cable TV as well as considering the advance technological convergence proposed, Government Information Office (GIO) proposed the adjustment of the existing 47 franchise districts to a single franchise area in three phases in its Jan. 2003 report. The re-arrangement of the franchise region will cause a revolution in the industry. How will it influence those system operators? Is it possible to develop into another cable TV war by cutting prices to gain benefits of audiences? Do system operators have any action plans for the change? Can this policy benefit the industry¡¦s development? This article will provide detailed discussions on these major issues. There are two ways to go about the research. The first is by the means of questionnaire; distribution of questionnaires to 62-system owners in Taiwan results in 54 effective samples gathered. The second is by means of in-depth interview; conducting interviews with industrial, legislative, and academic experts. After statistical analysis and content analysis, the research findings from these interviews are as follow: 1. The re-arrangement of cable TV franchise regions might cause significant competition between system operators. In the long run, it is unlikely that the cable TV industries will apply vicious competition tactics as previously done. It is believed that strategic alliance, stock exchange, and multiple service strategies will be implemented instead. 2. Under the influence of re-arranging franchise region policy and increasing new entry competitions, most system operators will focus on strengthening their network upgrade, customer service, and professional employee training. They are also likely to develop new business opportunities and to engage in cost-saving activities. 3. Most system operators support the policy with positive anticipation. The regulatory authority expects tremendous benefits for both audiences and cable industry. The scholars project an improvement in operators¡¦ customer service quality. In summary, the policy is expected to have a positive influence on cable industry¡¦s overall development. Since the policy has a major impact on the industry¡¦s future, it is essential to meet all development needs of the cable industry. As research suggests that the authorities should communicate with all related parties before rolling out the franchise regional adjustment policy.
204

Nonlinear Residual Income Model

Yeh, Chao-Hui 30 July 2001 (has links)
Nonlinear Residual Income Model Abstract Residual income has been proven to be a new approach of value relevance recently. The purpose of this study is to introduces residual income completely, and hopefully make some creativeness and contribution to residual income model. This paper is a both modeling and empirical study. In modeling, we have the following results¡G (1) Next period residual income is a nonlinear function of this period residual income, when we consider managers¡¦ real option. (2) This study introduces ¡§nonlinear residual income model¡¨ into Ohlson model, therefore firms¡¦ value is a nonlinear function of this period residual income. (3) This paper develops an option-based valuation model. According to this paper, equity value consists of the expected value from maintaining current operations, plus the value of the (put) option to discontinue operations at date t+1, and value of the (call) option to expand operations at date t+1. Empirical tests based on 27,536 firm-year observations from 1991-99 supports the above predictions of (1) and (2). In addition to the traditional OLS, this paper applies a new statistical approach--Sliced Inversed Regression (SIR). By SIR, we identify that our data has nonlinear components. This paper provides an alternative choice of valuation model and suggests that future research should approach the basic of value drivers.
205

The Pattern of the Spatial Distribution in Township-village Enterprises¢wRegional and Provincial Level Analysis

Chang, Jen-Yu 05 August 2002 (has links)
none
206

The Study of Organizational Change Management For Semiconductor Company--A Semiconductor Company Case Study

Chiu, Teng-Chu 24 June 2003 (has links)
The most significant challenge is ¡§ how to manage effectively organizational changes¡¨ while the organization is confronting with its strategic changes. In the course of practice, it would meet the environmental changes, effectively solidify unanimous opinions, strengthen the function of object management and the capability of managing changes, and improve the constitution of organization in order to achieve the optimal efficiency of entire operation, and estabilish the core competence of organization. Taiwan is facing to the heavy impact due to hi-tech industry move outside, especially in high-tech and high-valued semiconductor industry. And now the high-tech companies are facing to the transform of industry structure. The most important is how to enhance the competitive advantage to them. Besides operational efficiency, the speed is another critical factor to face the character of semiconductor industry either changing frequently or fast changing environment. Markets and tasks are both diversified and changeable, and the timing is also compressed quickly. Not only business operation has to accommodate with quick changes of environment, but also change ahead of marketing changes. The key point is to create or search the competitive niche for each company. Even though the strategy and organization structure will be changed for the need of the marketing environment, the factors that affect the organization structure including environment and strategies also have influence on organization operations as well as organization control and efficiency. But in the process of organization changing, not only focus on the adjustment of organization structure but further aware of the transform of corporation constitution and the development of human resource. In general company¡¦s performance of appraisal is based on the strategic plan, policy deploy and the calculation of the balance score card which are focused on the management of objective between inter-departments or stratums, but neglect the horizontal leakage among the departments or interspersions, and combine work tasks with the targets of individual development in the future. I create a ¡§combined sheet of the career plan¡¨ which improves the aforesaid defects, and make a more complete career plan sheet with illustrative case. In view of the practical experience personally, I realize that the most critical point is the personal expectation and permission in the course of organizational operating systematically. The combined sheet of the career plan also link up the targets of work tasks and individual development. In the meantime, the company fits with complete performance appraisal in order to induce and motive employees to set up some targets of individual development combined with work targets that would go deeply into the motivation and be lasting of work targets for employees. In this way, the employees will both give consideration to the performance in the personal and company. A semiconductor company, the study case of the thesis, experienced organizational regroup many times. The study focused on the different organizational types, the model of managerial operation, and the positive and negative influences on the organizational efficacy and internal control. The study in the aspect of organizational structure and changing management was involved deeply, and the environment and strategies was also described to some extent. The procedure of this study was mainly through the interview and review on the relevant reference documents related to the subject of organizational structure and changing management, meantime to have a better understanding on the development of regroup in the company for further analysis and presenting the proposal to the company, and expect to establish a valuable managerial model of organization change to improve the defects of organizational management, and to be applied in the progress of plan and management for reference.
207

Creation of an optimized acellular scaffold for improved vascular engineering

Nagao, Ryan Joseph 14 July 2014 (has links)
Engineering a complex tissue that exceeds 100-200 [mu]m requires a vascular connection. Methods to enhance vascularization include the delivery of angiogenic factors, and the use of scaffolds that encourage vascular ingrowth. However, these techniques rely on the host to vascularize the construct upon implantation, which is often too slow to provide nutrients to the entire construct. Hence, recent research has focused on creating de novo vascular networks prior to implantation. Such technologies would enable faster anastomosis with the host vascular system, as well as fully perfused constructs that can increase cell viability. Many techniques have been investigated to create de novo vascular networks with varying levels of success. Our approach was to utilize native vascular extracellular matrix (ECM) obtained from decellularizing highly vascularized tissue as a substrate for re-endothelialization and thus to create a three-dimensional vascular bed for ultimate use with various implant and tissue engineering applications. We have demonstrated a method of chemical decellularization that effectively removes cellular material while leaving behind an organized patent vascular network down to the capillary scale. Standard histological methods, DNA quantification, as well as vascular corrosion casting demonstrated this efficacy. Subsequent subcutaneous implantation then explantation of the scaffold at 7 and 28 days was used to assess the immunogenicity of the graft by analyzing the presence of immune cells. This scaffold was then re-endothelialized with human dermal microvascular endothelial cells (HDMECs) and conditioned with peristaltic flow for 60 hours to help improve vascular patency. Cellular distribution was determined qualitatively by first incubating the HDMECs with gold nanotracers, then imaging their presence upon implantation through ultrasound-guided photoacoustic (US/PA) imaging. Following the culture process, the scaffolds were analyzed for vascular patency through vascular corrosion casting, and cellular phenotype through histological methods---demonstrating a decrease in vascular damage. The re-endothelialized scaffolds were then assessed for functional vascular performance by perfusing whole blood through them. Results demonstrated better blood clearance in re-endothelialized scaffolds compared to scaffolds without cells. These results point to the ability of the optimized acellular (OA) scaffold to be used in future experiments focused on vascular and tissue engineering. / text
208

APPLICATIONS OF THE RE-OS ISOTOPIC SYSTEM IN THE STUDY OF MINERAL DEPOSITS: GEOCHRONOLOGY AND SOURCE OF METALS

Barra-Pantoja, Luis Fernando January 2005 (has links)
In mineral deposits the application of the Re-Os system has evolved on two fronts; as a geochronometer in molybdenite, and as a tracer of the source of metals by direct determination of the source of Os contained in the ore minerals. Results obtained from a wide variety and types of mineral deposits indicate that ore minerals in most deposits contain a high initial osmium composition, compared to the mantle value at the time of ore formation. The Re-Os data presented here for the Platreef, South Africa, adds to the growing notion that the crust plays a fundamental role in the formation of mineral deposits and as a source of ore minerals. Additional data from the Zambian Copperbelt illustrate the utility of the Re-Os system as a geochronometer of sulfide mineralization. Two isochron ages of ca. 825 Ma and 575 Ma are consistent with a long-lived period of multistage mineralization linked to basin evolution and support a model where brines play a fundamental role in the formation of sediment-hosted stratiform deposits.Numerous new Re-Os molybdenite ages have recently been reported; however, the behavior of Re and Os in molybdenites is still poorly understood and controversy remains regarding the possible disturbance of the Re-Os isotopic system. Previous studies indicate that the Re-Os system in molybdenites, and in other sulfides, can experience disturbance by Re and Os loss or Re gain (both examples of open system behavior), and that the analysis of these altered samples yields equivocal ages. Through replicate analyses of samples and/or comparison with other robust dating techniques, such as the U-Pb geochronometer, it is possible to differentiate between Re-Os molybdenite ages reflecting a mineralization age or a post depositional event. Once the reliability of the Re-Os molybdenite analyses is proven, it is possible to constrain the timing of mineralization and the identification of multiple molybdenite mineralization events, information that is relevant in assessing the longevity of porphyry systems.The examples presented in this work support the use of the Re-Os isotopic system as an important geochemical tool in the understanding of mineral deposits.
209

Examining the behaviour of re-gifting using a multi-method approach.

Ormandy, Elizabeth Mary January 2011 (has links)
This study investigated the behaviour of re-gifting using both qualitative and quantitative research methods. Re-gifting is the gift-giving behaviour of giving a gift that was previously given to you, to another with the pretence that you purchased the gift. The qualitative phase used semi-structured interviews to uncover an initial understanding of re-gifting behaviour from participants’ selected using purposive sampling. The main findings arising from this phase showed that re-gifters used three main factors to determine when it is appropriate to re-gift. These three factors, relationship, occasion and gift were used as the basis of the conceptual framework. This framework was then analysed using an online experiment with the use of vignette techniques which was the focus of the quantitative phase. The study focused on understanding what influences individuals decisions to re-gift. The main factors of interest were how the gift, occasion and relationships involved influenced re-gifting intentions. Re-gifting attitudes where analysed using the factors gift-giving attitudes, previous re-gifting experiences and frequency of re-gifting. A total of 211 responses were collected from Web users from around the world. The study suggests that re-gifters are influenced by the relationships involved and the type of gift, not the occasion. Re-gifting attitudes can be influenced by previous re-gifting experiences. This study has numerous practical implications, more specifically for retailers and charity organisations. This study adds major contributions to both gift-giving and disposition literature and introduces the area of re-gifting. Future research in cultural differences, gender differences and re-gifters versus non re-gifters suggested.
210

DistNeo4j: Scaling Graph Databases through Dynamic Distributed Partitioning

Nicoara, Daniel 14 October 2014 (has links)
Social networks are large graphs which require multiple servers to store and manage them. Providing performant scalable systems that store these graphs through partitioning them into subgraphs is an important issue. In such systems each partition is hosted by a server to satisfy multiple objectives. These objectives include balancing server loads, reducing remote traversals (number of edges cut), and adapting the partitioning to changes in the structure of the graph in the face of changing workloads. To address these issues, a dynamic repartitioning algorithm is required to modify an existing partitioning to maintain good quality partitions. Such a repartitioner should not impose a significant overhead to the system. This thesis introduces a greedy repartitioner, which dynamically modifies a partitioning using a small amount of resources. In contrast to the existing repartitioning algorithms, the greedy repartitioner is performant (in terms of time and memory), making it suitable for implementing and using it in a real system. The greedy repartitioner is integrated into DistNeo4j, which is designed as an extension of the open source Neo4j graph database system, to support workloads over partitioned graph data distributed over multiple servers. Using real-world data sets, this thesis shows that DistNeo4j leverages the greedy repartitioner to maintain high quality partitions and provides a 2 to 3 times performance improvement over the de-facto hash-based partitioning.

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