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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.
271

Studies on the factors which restrict acroporids recovering in the lagoon of Dongsha Atoll

Liu, Shu-ting 01 July 2011 (has links)
Many coral reefs around the world were damaged during the 1998 mass bleaching event. The acroporids in the lagoon of Dongsha Atoll were eliminated during massive bleaching, and they are still not recovered. Three hypotheses were proposed to explain how the lagoon of Dongsha Atoll has not recovered during the past twelve years¡G1. the lack of recruitment, 2. the persistent interfering on newly recruiting acroporids by hot water, 3.the interfering on those acroporids by predators. Four types of habitats, i.e., reef tops, reef slopes, reef bases, and inter-patch-reefs were surveyed on their coral communities, densities of juvenile corals, growth rates, pests and diseases of corals. The tissue samples were collected to assess reproductive status of corals. Moreover, Acropora muricata branches were transplanted from north coast of Dongsha Island to 3 m and 9 m depths in the lagoon of Dongsha Atoll for testing suitability of the environment. The acroporids were mature, and they spawned between March and May in 2010. Live coral coverage was 16% on average; small coral densities were 1.5/m2, much lower than other lagoons. Besides, acroporid represented 8% of coral coverage and 4% of juvenile corals which are lower than those of other lagoon. Water temperatures were higher in 2010 than 2009. However, coral skeletal extension rates do not show any reign of reduction. In addition, most acroporids survived 2010 summer¡]sea water temperature exceeded 30¢J¡G40-64%¡^ in the transplantation experiment. During two years of survey, only 6 individuals Acanthaster planci. So the lack of recruits might be the bottleneck to the recovery of acroporid in Dongsha lagoon.
272

Blocked and recovered memories of affective, distinctive, and neutral paragraphs

Corbisier, Barbara Lynn 15 May 2009 (has links)
Highly affective memories have been thought to be longer lasting and more detailed than other memories, and many experimental results have supported this assertion. The apparent robustness of these memories, however, may result from their high distinctiveness, rather than their emotional content. Two experiments tested free and cued recall for negative affect, distinctive, and neutral paragraphs. Experiment 1 compared neutral and negative affect paragraphs using a blocked and recovered memory technique. Affective paragraphs were remembered significantly better than neutral paragraphs in free recall of paragraph titles, regardless of condition. Details of neutral paragraphs were remembered significantly better than affective paragraphs, regardless of condition. No recovery effect was found. Experiment 2 compared distinctive and neutral paragraphs using the same technique. Free recall of paragraph titles did not differ between paragraph types. Neutral paragraphs were remembered better than distinctive paragraphs in cued recall, regardless of condition. Participants remembered significantly more with cued recall, and significantly more in the forget condition, and distinctive paragraphs were subject to a much greater forgetting effect than neutral paragraphs. It is unclear why a robust forgetting effect, using these stimuli, was not found. Consistent with previous literature, affective stimuli were remembered well, but inconsistently, distinctive stimuli were not. These results provide support for the claim that negative affect memories are more robust than other memories. This may result from their inherent emotional content as opposed to their being distinctive in some way.
273

Study of CO2 Mobility Control Using Cross-linked Gel Conformance Control and CO2 Viscosifiers in Heterogeneous Media

Cai, Shuzong 2010 August 1900 (has links)
CO2 has been widely used as a displacement fluid in both immiscible and miscible displacement processes to obtain tertiary recovery from the field. There are several problems associated with the application of CO2 flooding, especially when there is a significant presence of heterogeneous elements, such as fractures, channels and high permeability streaks within the reservoir. With flooding, CO2 will finger through the target zone while leaving most of the residual/trapped oil untouched. As a result, early gas breakthrough has been a very common problem in CO2-related projects, reducing the overall sweep efficiency of CO2 flooding. This research aims at improving the CO2 flood efficiency using cross-linked gel conformance control and CO2 viscosifier technique. A series of coreflood experiment studies have been performed to investigate the possibility of applying CO2 mobility control techniques. Corresponding simulation works have also been carried out to predict the benefits of applying CO2 mobility control techniques in the field. In the laboratory study, the CO2 coreflood system was integrated with the CT (Computed Tomography)-scanner and obtained real-time coreflood images of the CO2 saturation distributions in the core. This system was applied to the research of both cross-linked polymer gel treatment and CO2 viscosifier study and produced images with sharp phase contrasts. For the gel conformance study, promising results were obtained by applying cross-linked gel to eliminate permeability contrast and diverting CO2 into low permeability regions to obtain incremental oil recovery; also studied were the gel strength in terms of leak-off extent with the aid of CT (Computed Tomography) images. For the CO2 viscosifier research, we tested several potential viscosifier chemicals and found out PVAc (Polyvinylacetate)/toluene combination to be the most promising. The follow-up study clearly demonstrates the superiority of viscosified CO2 over neat CO2 in terms of sweep efficiency. This research serves as a preliminary study in understanding advanced CO2 mobility control techniques and will provide insights to future studies on this topic.
274

Generalized Correlations to Estimate Oil Recovery and Pore Volumes Injected in Waterflooding Projects

Espinel Diaz, Arnaldo Leopoldo 2010 December 1900 (has links)
When estimating a waterflood performance and ultimate recovery, practitioners usually prepare a plot of log of water-oil ratio vs. cumulative production or recovery factor and extrapolate the linear section of the curve to a pre-established economic limit of water production. Following this practice, engineers take the risk of overestimating oil production and/or underestimating water production if the economic limit is optimistic. Engineers would be able to avoid that risk if they knew where the linear portion of the curve finishes. We called this linear portion the "straight-line zone" of simply SLZ. In this research, we studied that ―straight-line zone‖ and determined its boundaries (beginning and end) numerically using mathematics rules. We developed a new procedure and empirical correlations to predict oil recovery factor at any water/oil ratio. The approach uses the fundamental concepts of fluid displacement under Buckley-Leverett fractional flow theory, reservoir simulation, and statistical analysis from multivariate linear regression. We used commercial spreadsheet software, the Statistical Analysis Software, a commercial numerical reservoir simulator, and Visual Basic Application software. We determined generalized correlations to determine the beginning, end, slope, and intercept of this line as a function of rock and fluid properties, such as endpoints of relative permeability curves, connate water saturation, residual oil saturation, mobility ratio, and the Dykstra-Parsons coefficient. Characterizing the SLZ allows us to estimate the corresponding recovery factor and pore volumes injected at any water-oil ratio through the length of the SLZ . The SLZ is always present in the plot of log of water-oil ratio vs. cumulative production or recovery factor, and its properties can be predicted. Results were correlated in terms of the Dykstra-Parsons coefficient and mobility ratio. Using our correlations, practitioners can estimate the end of the SLZ without the risk of overestimating reserves and underestimating water production. Our procedure is also a helpful tool for forecasting and diagnosing waterfloods when a detailed reservoir simulation model is not available.
275

Fast Reroute with Pre-established Bypass Tunnels in MPLS

Cheng, Chen-Chang 01 September 2003 (has links)
This paper proposes a new approach to support restoration of Label Switched Paths (LSP) set up in the MPLS network. The proposed scheme tries to establish all possible bypass tunnels according to the maximum bandwidth between two LSR around the protected Label Switched Router (LSR). The proposed scheme uses the idea of the maximum bandwidth between two LSRs and establishes the bypass tunnels passing through the critical links which will affect the maximum bandwidth between two LSRs. All of LSPs affected by a LSR failure or a link failure can choice a bypass tunnel fit its QoS constraints to reroute. This paper also compares the different between the proposed bypass tunnel and link disjoint bypass tunnel. The simulation result show that the proposed approach has better packet loss in rerouting and can allow more affected LSP to reroute compare to RSVP and efficient Pre-Qualify. The proposed bypass tunnels have better performance than link disjoint bypass tunnels.
276

The Application of Credit Risk Models on Asset Securitization¡ÐConsidering the Micro and Macro Factors

Chung, Chia-yuan 17 June 2005 (has links)
none
277

none

Lin, Ya-lan 03 July 2005 (has links)
none
278

Research On The Recovery of Semi-Fragile Watermarked Image

Sun, Ming-Hong 03 July 2006 (has links)
In recent years, there are more and more researches on semi-fragile watermarking scheme which can resist JPEG compression. But, there are few researches focused on the recovery of semi-fragile watermarked image. Therefore, in this paper, we not only present a semi-fragile watermarking scheme which can resist JPEG compression but use the error correction code (Reed-Solomon Code) to recover the area being malicious manipulated. At first, we use the semi-fragile watermarking scheme proposed by Lin and Hsieh to detect the counterfeit under the JPEG compression [9]. Its main effect is to resist JPEG compression and to detect the attacked parts without the need of the original image. And then, we will introduce how we use RS code to recover the attacked parts being detected by the semi-fragile watermarking scheme. We use the scheme ¡§Interleaving¡¨ to spread the local pixels to the global area. Next, we encode to each little image block by RS code. The redundant symbols generated by RS code will be signed to be signature attached with the watermarked image. Finally, the receiver can use semi-fragile watermarking scheme to detect attacked part and use the information of the signature to decode these attacked parts. Additionally, we also discuss how to decrease the load of the signature, thus, it can not significant loading of the watermarked image.
279

The influence of Heat-Pipe Waste Gas Recovery System and Energy Recycling System to Global Competition of Enregy Intensive Industries in Taiwan

Yao, David 03 July 2007 (has links)
The shortage of energy supply against growing demand globally has caused seriously impact to all industries, dead or alive, especially for the energy intensified industries, like oil refinery (Petroleum) Iron and Steel making industries which has been confronting tremendously with pressing concern for survival. Even both industries are within traditional industrial factor, but represent as key and fundamental industries as relied on, by all industries of a Nation. Therefore, all the international enterprises dealing with high-temperature production have been striving for long-term supply & steady quality of raw material of energy. Under this circumstance, the enterprises shall be offering to find the measures for cost-down of energy consumed, and further utilize the waste gas and heat as generated out of the production, that would surely produce the efficiency of energy, and not only diminish the dependence on primary energy, it also can effectively reach the goal of ¡§Independence of Energy¡¨ and optimization for the control of energy cost. This study is adopting the case study of Company ¡§C¡¨, with the analysis of SWOT, Five-force Analysis, and Diamond Model by Michael Porter, to further analyze the overall environment and circumstance of energy intensified industries. So that, it might help to understand further the strength and weakness of the energy intensified industries of our nation. First of all, to proceed the survey for the application of waste heat recovery system to energy intensified industries, and secondly, the application of waste heat recovery system to energy intensified industries in Taiwan, to generate direct and indirect efficiency whether or not to escalate the overall competitiveness to face the global competition. This research recognize the No. 1 pressure & bottle neck of the energy intensified industry lies mainly in the insufficiency of energy supply, and the upcoming environmental protection is getting more conscious & concerned. Therefore, all the industrialized countries have moved further forward to reinforce the energy saving technology, and increase the efficiency of energy using, developing new generation of energy with more efforts. Adoption of Company ¡§C¡¨, has recognized the following benefit, after the introduction of Waste Gas Heat Recovery System: 1. Recovery of Waste Gas of Hot Blast Stove, reduction of COG use, to transfer the saved COG to down-stream, to substitute the expensive natural gas, which is benefit to Company ¡§C¡¨ in the respect of energy saving. 2. Increasing the operation efficiency of hot blast stove, to have operation technique more Sophisticated, in the meantime, to eradicate the moisture out of BFG/Air and further extend the life time of ceramic burner of hot blast stove. 3. The Waste Gas Heat Recovery System has been totally mature with good reference of operation in the world market, which has been used by most steel mills in the world. There is actually no risk to adopt and apply this technology, & further carve out the good image of company ¡§C¡¨ in the respect of energy saving. 4. Reduction of SOx out of waste gas, and further diminish the temperature of waste gas released and can reduce the CO2 emission that is friendly to our environment. The research of this study recognized further, that energy intensified industry has been built up due to the scenario and situation of Taiwan in past few decades, in view of the development of economy, which is crucial industry & business sector. However, with the time running, the energy intensified industry requires to be adjusted for adaptation to the industrial environment of energy crisis and global warming. In this case, the largest potential worry for Taiwan is obviously insufficiency of energy supply. Furthermore, the technical level of energy saving of Taiwan is far more behind Japan, & many other European countries. General Speaking, the energy intensified industry of Taiwan is in weak situation at this moment. If Taiwan might introduce more advanced technology, and technical cooperation, technical research and development, or even training of qualified personnel enabling to upgrade the energy saving of Taiwan to be further upgraded for increasing the competitiveness of industries which is surely positive for a nation being more competitive. In view of energy intensified industry, shortage of energy supply and the price be kept high end, the recycling energy is not available within short time, for short and mid term, the best effective measures to solve the problem of energy is to reduce the amount of energy, for long run, it is great help to use the energy saving system to the energy intensified industry. For one hand, it might reduce the production cost; on the other hand, it can increase the energy operation efficiency. The heat pipe Waste Gas Heat Recovery System as described in this Study is well sound technology of energy saving.
280

Design and construction of a left ventricular cardiovascular assist device

Vedi, Manmeet Singh 15 November 2004 (has links)
Congestive heart failure (CHF) is a debilitating condition that afflicts 4.8 million Americans with an increasing incidence. Each year, there are an estimated 400,000 new cases. The incidence is on the rise as the age of the population is increasing and because most people are surviving their first heart attack. Pharmacological therapies are improving, yet many patients still reach end-stage heart failure and there are too few donor hearts available. This thesis is presented as a first small step in a long process in the design and development of a novel cardiac assist device that would ultimately heal a diseased heart by the process of ventricular recovery. The device acts to restore the kinematics of a diseased heart by modulating the extra ventricular displacements. The first surgery / trial were conducted on a bovine at the Veterinary School at Texas A&M University. Main objectives of the surgery were to test the method of attachment of the device and power requirements of the device. Details regarding the design and construction of the device have been presented in the thesis.

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