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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.
111

The winter distribution, movement, and smolt transformation of juvenile coho salmon in an Oregon coastal stream

Rodgers, Jeffrey D. 05 May 1986 (has links)
The abundance of the 1982 brood of juvenile coho salmon (Oncorhynchus kisutch) was determined in August 1983, and January and April 1984 at 20 study sites spread throughout Knowles Creek, an Oregon coastal watershed. The timing of emigration of juvenile coho from the watershed was monitored from October 1983 through June 1984. Condition factor, fork length, and gill (Na+K)-ATPase activity were measured in migrants, a captive group of Knowles Creek juvenile coho held in the laboratory, and nonmigrant fish periodically sampled from the stream. Skin guanine levels were also measured in migrant and nonmigrant groups. Juvenile coho abundance in January was significantly correlated with abundance in August. Wood volume and amount of undercut streambank were the pair of physical variables that best explained variation in the number of fish per square meter or per cubic meter in January. Two debris torrent ponds in the middle of the watershed contained large amounts of woody debris and were the most heavily used overwintering habitats for juvenile coho in the Knowles Creek. Few juvenile coho overwintered in the lower half of watershed, an area lacking woody debris. Peaks in outmigration occurred in November and May. Approximately 24% of the total number of migrants emigrated in November. Fish that reared in two of three third-order areas in summer, together with fish from the lower (fifth-order) half of the mainstem, were the first to leave the watershed. While lack of winter habitat may have been the cause of migration from the lower mainstem, low summer streamflows may have caused early migration from the low order sites. Gill (Na+K)-ATPase activity of migrants rose gradually from a low in January to a peak at the end of the study in June. Mean gill (Na+K)-ATPase activity of nonmigrants was only significantly lower than that of migrant fish during April. Gill (Na+K)-ATPase of captives was similar to that of nonmigrants until it peaked during the last two weeks in April, after which the activity fell below that of migrants or nonmigrants. Condition factor of nonmigrant fish was higher than either migrants or captives throughout the study. Migrant skin guanine levels rose sharply during the first two weeks in April and continued to rise until the end of the study in June. Approximately 8,300 juvenile coho, 44% of the estimated number of juvenile coho present in Knowles Creek in August, migrated from the watershed by the following June. An estimated 9% of the August population migrated as smolts after April 1. / Graduation date: 1986
112

Security proof methods for quantum key distribution protocols

Ferenczi, Agnes January 2013 (has links)
In this thesis we develop practical tools for quantum key distribution (QKD) security proofs. We apply the tools to provide security proofs for several protocols, ranging from discrete variable protocols in high dimensions, protocols with realistic implementations, measurement device independent QKD and continuous-variable QKD. The security proofs are based on the Devetak-Winter security framework [I. Devetak and A. Winter, Proc. of the Roy. Soc. of London Series A, 461, 207 (2005); B. Kraus, N. Gisin, and R. Renner, Phys. Rev. Lett., 95 080501 (2005)]. In the key rate calculation, it is often convenient to assume that the optimal attack is symmetric. Under the assumption that the parameter estimation is based on coarse-grained observations, we show that the optimal attack is symmetric, if the protocol and the postselection have sufficient symmetries. As an example we calculate the key rates of protocols using 2, d and d+1 mutually unbiased bases in d-dimensional Hilbert spaces. We investigate the connection between the optimal collective eavesdropping attack and the optimal cloning attack, in which the eavesdropper employs an optimal cloner to attack the protocol. We find that, in general, it does not hold that the optimal attack is an optimal cloner. However, there are classes of protocols, for which we can identify the optimal attack by an optimal cloner. We analyze protocols with mutually unbiased bases in d dimensions, and show that for the protocols with 2 and d+1 mutually unbiased bases the optimal attack is an optimal cloner, but for the protocols with d mutually unbiased bases, it is not. In optical implementations of the phase-encoded BB84 protocol, the bit information is usually encoded in the phase of two consecutive photon pulses generated in a Mach-Zehnder interferometer. In the actual experimental realization, the loss in the arms of the Mach-Zehnder interferometer is not balanced, for example because only one arm contains a lossy phase modulator. Since the imbalance changes the structure of the signals states and measurements, the BB84 security analysis no longer applies in this scenario. We provide a security proof for the unbalanced phase-encoded BB84. The loss does lower the key rate compared to a protocol without loss. However, for a realistic parameter regime, the same key rate is found by applying the original BB84 security analysis. Recently, the security of a measurement device-independent QKD setup with BB84 signal states was proven in Refs. [H.-K. Lo, M. Curty, and B. Qi, Phys. Rev. Lett., 108 (2012); S. L. Braunstein and S. Pirandola, Phys. Rev. Lett., 108 (2012)]. In this setup Alice and Bob send quantum states to an intermediate node, which performs the measurement, and is assumed to be controlled by Eve. We analyze the security of a measurement device-independent QKD protocol with B92 signal states, and calculate the key rates numerically for a realistic implementation. Based on our security proof we were able to prove the security of the strong reference pulse B92 protocol. We analyze the security of continuous-variable protocols using the entropic uncertainty relations established in Ref. [M. Berta, M. Christandl, R. Colbeck, J. M. Renes, and R. Renner, Nature Physics 6, 659 (2010)] to provide an estimate of the key rate based on the observed first and second moments. We analyze a protocol with squeezed coherent states and the 2-state protocol with two coherent states with opposite phases.
113

Operated device estimation framework

Rengarajan, Janarthanan 15 May 2009 (has links)
Protective device estimation is a challenging task because there are numerous protective devices present in a typical distribution system. Among various protective devices, auto-reclosers and fuses are the main overcurrent protection on distribution systems. Operation of a protective device in response to a particular fault condition depends upon the protective device’s operating behavior and coordination of various such protective devices. This thesis presents the design and implementation of a protective device estimation algorithm which helps in identifying which protective devices have operated to clear a short circuit condition. The algorithm uses manufacturer’s device details, power quality data measured from substation monitoring devices and power system event features estimated using existing DFA algorithms. The proposed technique can be used to evaluate coordination of these protective devices and helps in locating a fault in a distribution system feeder. This approach is independent of feeder topology and could be readily used for any distribution system. The effectiveness of this algorithm is verified by simulated and actual test data. Suggestions are included for future research and application by electric utilities.
114

Variation and power issues in VLSI clock networks

Venkataraman, Ganesh 15 May 2009 (has links)
Clock Distribution Network (CDN) is an important component of any synchronous logic circuit. The function of CDN is to deliver the clock signal to the clock sinks. Clock skew is defined as the difference in the arrival time of the clock signal at the clock sinks. Higher uncertainty in skew (due to PVT variations) degrades circuit performance by decreasing the maximum possible delay between any two sequential elements. Aggressive frequency scaling has also led to high power consumption especially in CDN. This dissertation addresses variation and power issues in the design of current and potential future CDN. The research detailed in this work presents algorithmic techniques for the following problems: (1) Variation tolerance in useful skew design, (2) Link insertion for buffered clock nets, (3) Methodology and algorithms for rotary clocking and (4) Clock mesh optimization for skew-power trade off. For clock trees this dissertation presents techniques to integrate the different aspects of clock tree synthesis (skew scheduling, abstract topology and layout embedding) into one framework- tolerance to variations. This research addresses the issues involved in inserting cross-links in a buffered clock tree and proposes design criteria to avoid the risk of short-circuit current. Rotary clocking is a promising new clocking scheme that consists of unterminated rings formed by differential transmission lines. Rotary clocking achieves reduction in power dissipation clock skew. This dissertation addresses the issues in adopting current CAD methodology to rotary clocks. Alternative methodology and corresponding algorithmic techniques are detailed. Clock mesh is a popular form of CDN used in high performance systems. The problem of simultaneous sizing and placement of mesh buffers in a clock mesh is addressed. The algorithms presented remove the edges from the clock mesh to trade off skew tolerance for low power. For clock trees as well as link insertion, our experiments indicate significant reduction in clock skew due to variations. For clock mesh, experimental results indicate 18.5% reduction in power with 1.3% delay penalty on a average. In summary, this dissertation details methodologies/algorithms that address two critical issues- variation and power dissipation in current and potential future CDN.
115

Study how the educational voucher system influence the government's policy and parental choice.

Lin, Chen-Xuan 14 July 2004 (has links)
Abstract Education good is not only a kind of non-pure public good, but also has the character of external benefit. Government can make up for the market failure by intervene the education market, and sometimes it provides the subsidy for the education through public policies. This paper uses the educational vouchers to provide education subsidies in views of Friedman¡¦s ideal which manifests the goal of the freedom education market. Thus, parents have the chance to choose private schools for their children. The third chapter tries to establish the mixed-regime education model, and study the effects of tax-financing, education quality and the right of choosing schools when the government carries out the educational voucher system under the rule of majority voting. From this model, we find that the practice of educational voucher system has the influence on the income redistribution, and the voucher amounts would influence the education quality which children obtain. By the way, considering the factor of transaction efficiency, we study how the voucher amounts influence the tax-financing and study how to reduce the tax rates under the vouchers system. In this paper, we use the way of parameter simulation to study how the vouchers system influences the parent¡¦s choice on education in the different income distribution structure. In the forth chapter, we aim for the government behavior to the effects of education policies. The government¡¦s objective function includes both the weight of social welfare factor and self-interest of maximizing budget, so we study how the poor groups and rich groups independently choose the public education expenditure and educational vouchers. The fifth chapter is conclusion and offers the study direction in the future.
116

A Taxonomic and Distributional Study of Seagrass in Taiwan

Ko, Chih-jen 06 September 2004 (has links)
Ten species of seagrasses are recognized in Taiwan and adjacent islands. They are, namely, Halophila beccarii Aschers., Halophila decipiens Ostenf., Halophila ovalis (R. Br.) Hook. f., Thalassia hemprichii (Solms) Aschers., Cymodocea rotundata Ehrenb. & Hempr. ex Aschers., Cymodocea serrulata (R. Br.) Aschers. & Magnus, Syringodium isoetifolium (Aschers.) Dandy, Halodule pinifolia (Miki) den Hartog, Halodule uninervis (Forssk.) Aschers. and Nanozostera japonica (Ascherson & Graebner) Toml. & Posl. The detail morphological charactors of these speices are descripted for the first time, and can be the basis of further research. These species are mainly distributed in the west coast of Taiwan, Hengchun peninsula, the Green Island, the Orchid Island, Hsiaoliuchiu, the Pescadores Islands, Quemoy and the Pratas Island, the habitats can be categorized as 4 types, which are muddy to sandy tidal flat, coral platform, wave-cut platform and fine-muddy seabed. The relation between types of habitat and occurrence is also discussed.
117

A Study on the Blade Strength and the Dynamic Characteristics of Microturbines

Chen, Hsuan-sheng 01 July 2005 (has links)
The high speed mini or micro-turbo electrical power system¡]MTEPS¡^has been used widely as an important spare power source in different military purposes and all kinds of emergency facilities. The interaction between the centrifugal and pressure load on turbo blades of a high speed MTEPS system is investigated in this project. The effect of temperature on the strength variation of the turbo blades will be investigated by employing the thermal-mechanical- creep coupling model provided in the MARC finite element method package. The stress distribution of the compressor, turbine, rotor and blades are calculated. The combined effect of temperature, pressure and rotation speed on the stress and deformation of compressor and turbine blades was also evaluated and compared in this project.
118

Study of Load Transfer and Outage Restoration for Distribution Systems

Huang, Yu-Hsiung 05 July 2006 (has links)
The distribution system is the downstream of a power system, which is used to provide high reliability and quality electricity service for customers. Because of the wide area with voluminous facilities, involves in a distribution system, the preventive maintenance of distribution system components is important for the distribution system. For a fault contingency, the utility company has to identify the fault location to isolate the fault and to restore the electricity service for the un-faulted but outage area as soon as possible to enhance the service reliability. With the advancement of compute technology, the distribution automatic system (DAS) has been applied to solve the fault contingency problem by integrating the geographic information system (GIS) real time database (RTDB) relational database with master station and communication systems for the monitor and control of distribution systems. To achieve the function of fault detection, isolation and restoration (FDIR) of distribution automatic system, the FDIR software has been developed with C++ platform. By retrieving the distribution system components in GIS, the Topology processor is applied to identify the connectivity of distribution network. When a fault occurs, the fault flags will be generated and retrieved from the field feeder terminal unit (FTU) according to the states of fault flag and network configuration, therefore the fault location is identified very quickly. After isolate the faulted section, the feeder circuit breaker is closed to restore the upstream service. Based on the loading levels of supporting feeders, the downstream restoration is therefore obtained by closing the normal open switch, besides the application software can also be used to derive the optimal switching operation for loading balance of distribution feeders to enhance the operation efficiency of distribution systems.
119

Composition and distribution of Ichthyoplankton in the waters off Southwestern Taiwan

Liao, Chen-Hen 01 September 2000 (has links)
Abstract: There were 75 families, 119 genera and 182 species of ichthyoplankton found in the adjacent areas of Kaohsiung and Liuchiu Yu Island. Fifty families, 82 genera and 111 species were collected in the surface waters, and 37 families, 54 genera and 68 species were collected in oblique tows to 100m with an open 1 m net, while 41 families, 48 genera and 73 species were collected by a multiple opening-closing net. Engraulis japonicus was the most dominant species, and was found all year round; other dominant species included coastal fish species (Apogonidae and Pomacentridae), anadromous species (Scombridae), oceanic species (Engraulidae and Myctophidae), and demersal species (Gobiidae). There were only 3 species of ichthyoplankton belonging to 3 genera and 2 families found in the Tapong Bay, all these species are benthic species. The coastal waters of Kaohsiung and Liuchiu Yu Island might be influenced both by the river and the topography of Kaping Trench, and thus the hydrological conditions of this area were more complex, and the ichthyoplankton was more diverse. On the other hand, the hydrological conditions of the semi-closed Tapong Bay changed less than that of the estuary of Kaoping river, thus the species composition of larval fish was simple and less diverse. Overall, the highest abundance of the ichthyoplankton in the adjacent areas of Kaohsiung and Liuchiu Yu Island was found in the wet season(June), with an average of 108¡Ó 116 ind./100 m3. E. japonicus was the most abundant in February, revealed that might be the breeding season of this species. Other dominant species (eg. Bregmaceros japonica and Tridentiger sp.) also showed significant seasonal variation. Higher abundance of ichthyoplankton was usually found in the entrance of Kaohsiung first harbor(St.1) and the estuary of Kaoping river(ie. St.4~6). No significant diel vertical migration of the ichthyoplankton was observed in this study. Most ichthyoplankton were found in the water column above 100 m during both day and night.
120

Some Characterizations of the Exponential Distribution related to a Single-server Queueing System with an Unreliable Server

Wu, Sin-Ru 20 July 2002 (has links)
Consider a single-server queueing system with an unreliable server and service repetition. In this system, if the service is interrupted, the service is restarted anew immediately and ends whenever the service period is failure free. In this paper, we give some characterization of the exponential distribution by the constancy of total service time in this system. The result can be viewed as a kind of memoryless property of the exponential distribution.

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