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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.
151

Differential Equations and Depth First Search for Enumeration of Maps in Surfaces

Brown, Daniel January 1999 (has links)
A map is an embedding of the vertices and edges of a graph into a compact 2-manifold such that the remainder of the surface has components homeomorphic to open disks. With the goal of proving the Four Colour Theorem, Tutte began the field of map enumeration in the 1960's. His methods included developing the edge deletion decomposition, developing and solving a recurrence and functional equation based on this decomposition, and developing the medial bijection between two equinumerous infinite families of maps. Beginning in the 1980's Jackson, Goulden and Visentin applied algebraic methods in enumeration of non-planar and non-orientable maps, to obtain results of interest for mathematical physics and algebraic geometry, and the Quadrangulation Conjecture and the Map-Jack Conjecture. A special case of the former is solved by Tutte's medial bijection. The latter uses Jack symmetric functions which are a topic of active research. In the 1960's Walsh and Lehman introduced a method of encoding orientable maps. We develop a similar method, based on depth first search and extended to non-orientable maps. With this, we develop a bijection that extends Tutte's medial bijection and partially solves the Quadrangulation Conjecture. Walsh extended Tutte's recurrence for planar maps to a recurrence for all orientable maps. We further extend the recurrence to include non-orientable maps, and express it as a partial differential equation satisfied by the generating series. By appropriately interpolating the differential equation and applying the depth first search method, we construct a parameter that empirically fulfils the conditions of the Map-Jack Conjecture, and we prove some of its predicted properties. Arques and Beraud recently obtained a continued fraction form of a specialisation of the generating series for maps. We apply the depth search method with an ordinary differential equation, to construct a bijection whose existence is implied by the continued fraction.
152

The intraday pattern of information asymmetry : evidence from the NYSE

Wang, Juan 11 September 2009 (has links)
Previous studies (e.g. Benston and Hagerman, 1974, Bagehot, 1971 and Stoll, 1978) suggest that the bid-ask spread consists of three components: asymmetric information cost, inventory holding cost, and order processing cost. Other literature (e.g. Brock and Kleidon, 1992, Hef-lin et al, 2007, and McInish and Van Ness, 2002) reports that the bid-ask spread varies during a trading day following a U-shaped pattern. One explanation for this observation is that it is the result of changes in information asymmetry costs over the trading hours, assuming the other costs are fixed. However, no empirical study directly measures how information asym-metry changes over the trading day. We explore how this measure relates to the spread as well as the quote depth.<p> Our research divides a trading day into 13 half-hour trading intervals and measures in-formation asymmetry during each interval following the model developed by Madhavan and Smidt (1991) and Noronha et al (1996). Their model can directly estimate the level of infor-mation asymmetry in each interval. This enables us to observe the intraday pattern of infor-mation asymmetry directly and compare it to the patterns of the spread and the quote depth. Furthermore, we test the relationship between the spread and the information asymmetry and the relationship between the depth and the information asymmetry in a dynamic context to see how market makers manage information risk over trading hours.<p> We find that the risk of information asymmetry varies significantly during the trading day. There is a large drop over the first interval, and another large drop over the last interval, with smaller fluctuations over the remaining intervals. Moreover, we show that the spread is consistent with an L-shaped pattern as opposed to the U-shaped pattern proposed by previous studies while the depth is increasing throughout the 13 trading intervals. Furthermore, we ob-serve that the variations of the spread and the depth are respectively positively and negatively related to the intraday variations in the degree of information asymmetry across the trading intervals. In particular, a large decline in information asymmetry at the beginning of the day is associated with a large reduction in the spread, whereas a large decline in information asymmetry at the end of the day is associated with a large increase in the quote depth. This emphasises the importance of studying both measures of liquidity simultaneously.
153

Studies on the spatial distribution of coral communities in Dongsha Lagoon

Huang, Teng-yi 05 February 2010 (has links)
The purpose of this study is to investigate the factors that are responsible for the distribution of coral communities in the lagoon of the Dongsha Atoll. Previous surveys proposed that there was significant difference of coral cover between the east and west sides of the lagoon. Two hypotheses, seawater temperature and water depth, were proposed to explain the spatial variation of coral distribution. In addition, the growth rate of poritid corals, coral recruits, sexual reproduction, and the occurrence of coral predators and diseases were also studied. Ten patch reefs 5 on the west and 5 on the east sides in the lagoon were selected and the corals on reef tops (1-3 m) and deep reef bases (10-15 m) were investigated. The growth rates of poritid corals on reef tops were higher on reef bases than those on reef tops, and higher in eastern lagoon than those in western lagoon. On average, the growth rate is 0.9 cm/year. A total of 10 families of small corals were recorded in which Faviidae (61.6%), Fungiidae (16.6%) and Poritidae (9.7%) constituted the majority. Diversity index comparisons indicated that reef bases have higher diversities than reef tops. The densities of small corals, ranging between 0.1-3.0 ind./m2, are higher on reef bases than on reef tops. In fungiids, individuals in the eastern lagoon were larger than those in the western lagoon. Tissues of corals were sampled in June 2009 for examination of gonads. However, no reproductive tissues were found after decalcification and histology. The morphological classes, live-coral coverage, dead-coral coverage and dead-coral ratio among the comparisons of reef bases vs reef tops and western vs eastern lagoons, only dead-coral coverage was found to be higher in eastern than in western lagoon. The live-coral coverage was 0.3-46%, dead-coral coverage was 8%-76% and dead-coral ratio was 10%-100%. Among the 10 patch reefs, patch reefs 6, 7, 9 and 10 are represented by mostly K type competitors and belongs to Conservation Class 2, patch reefs 1, 2 and 3 are presented by mostly S type stress-tolerated corals and belongs to Conservation Class 1. The remaining 3 patch reefs 4, 5 and 8 belong to the highest Conservation Class 4 and are represented by diverse types of corals. The water temperature exceeded 30¢XC in 36% of the time at reef tops, and 13% of the time at reef bases, during the summer period, i.e., between June and September, 2009. And the water temperatures were found in 95% of the time to be ~ 1¢XC higher at reef tops than at reef bases. The water temperatures were also higher in the west than in the east of the lagoon that 29% of the time exceeded 30¢XC in the west and 9% in the east only. No coral diseases or pests were found that may pose a large-scale threat in the near future. The variations of coral fauna found among habitats in the lagoon are consistent with the temperature patterns, i.e., the higher the temperature the poorer the coral condition. To the two hypothesis, in the eastern or western lagoon and the different depth are the factors of coral distribution in the lagoon.
154

Why Do You Vote for Independent Candidates? A In-depth Case Study of 2010 Kaohsiung City Council Election

Chang, Hsi-Hua 04 January 2011 (has links)
This thesis explores reasons why a voter would vote for a ¡§independent¡¨candidate in a city council¡¦s election. Since respondents in a telephone survey are not able to give their thoughts and description of vote intention thoroughly. given few survey questions .I therefore chose in-depth interview conducted before the election day to explore the real thoughts of the voters. My in-depth interview respondents are selected by telephones surveys and were interviewed regarding four topics, including party identification, political views, candidates and social networks. I find that partisanship is not the main factor of voting for an independent candidate. Instead, the key is his or her ability to serve the voters. The second factor is the ability to execute the public welfare policies and the third is education background and experiences in the field of public service. Fourth social network has limited effects on voters who were born in the 70¡¦s and 80¡¦s. Moreover, I discovered that the effects of the party ideology on voting behavior might differ across levels of elections. In particular, Kaohsiung voters will take the cue of party ideology at the city mayor¡¦s election, while this may not apply to a city council¡¦s election.
155

Study of Eco-tourism Development in the Houbihu Protection Area

Lee, Ming-Chang 19 July 2011 (has links)
Abstract Eco-tourism gives consideration to both ecological conservation and recreation, aiming to protect resources by means of making tourists recognizing the importance of ecosystem."Houbihu Marine Conservation Area "in the National Kenting Park is established for the conservation of biological diversity from protecting sea urchins in 2003 to all marine organisms two years later. Recovery of marine resources encouraged the idea to develop eco-tourism in the area; not only to propagate the benefits from resources conservation by allowing tourists for near contacts to marine ecosystem and sharing the achievements of protection, but also to promote transformation of local fishers and to improve their economic conditions. This study explores the feasibility of this idea, by literature reviews, questionnaire survey and in-depth interview with the six groups of people: tourists, managers, enforcement officials, experts (including scholars), industries and non-government organization. Discussions on the results and recommendations were provided in the study. ¡ikeyword ¡jEco-tourism¡BBiologicaldiversity¡BHoubihuMarine¡Bliterature reviews¡Bquestionnaire survey¡Bin-depth interview
156

Studies on the Surface Characteristics of Steel by Electrochemical Buffing Using Conductive Polymer Tools

TSAI, Hsin-Ying 16 August 2011 (has links)
In this study, a conductive polymer is used as tool electrode in machining the stainless steel surface by electrochemical buffing. Using a very small working current of this conductive polymer, the material of the workpiece is dissolved, and the peaks on the workpiece surface is buffed by the abrasive simultaneously. A mirror-like surface can be achieved with high efficiency using this novel method. In the micro-electrochemical machining experiments, the initial surface roughness of the workpiece is about Rmax = 1.645 £gm, the average speed of electrode 25 mm/sec, the machining time 10 min, the electrolyte temperature 25¢J, and the stroke 10 mm. The variable conditions are given as follows: the sodium nitrate (NaNO3) electrolyte of 0 to 40 wt%, the normal load of 0 to 20 N, and the working current of 0 to 100 mA. Experimental results show that the minimum surface roughness of the workpiece can be achieved to about Rmax = 0.3£gm at the electrolyte concentration of 20 wt%, the working current of 25 mA, and the normal load of 10N, which is selected as the optimum operative parameters in the following. The silicon carbide with average particle size of 9.5£gm is added to conduct the electrochemical buffing experiments. Compared with the micro-electrochemical machining method, results show that the maximum machining depth increases to about two times, and the surface roughness decreases to about 50%. In this condition, the mirror-like surface of the workpiece with the working depth of 1.5£gm and Rmax of 0.15£gm can be achieved.
157

Equatorial Pacific Sediment Deposition during the Early to Middle Miocene: Carbon Cycling and Proxies for Productivity

Piela, Christine Marie 2010 December 1900 (has links)
The equatorial Pacific is a major region of biological production in the world oceans and an important part of the global carbon cycle. Changes in climate during the Cenozoic (65 Ma to present) have impacted the carbon cycle, and it is important to assess these impacts. This study focuses on the primary productivity of the equatorial Pacific during the early to middle Miocene (24 - 12 Ma) as recorded by Deep Sea Drilling Project (DSDP) Site 574, and investigates the sedimentary components potentially linked to productivity: bio-Ba, bio-SiO₂, Corg, CaCO₃, and uranium, as well as detrital thorium to estimate clay-bound barium. Within this time frame the plate beneath Site 574 traveled northwesterly across the equator and allows a unique opportunity to monitor changes in productivity and the carbon cycle in this region. It is difficult to determine directly primary productivity from the sedimentary record because the preservation of different proxies for this parameter - Corg, bio-CaCO₃, and bio-SiO₂, can be highly variable. The variability has many causes, including nutrient recycling in the water column and the depth of the carbonate compensation depth (CCD), which prevents the preservation and ultimate burial of plankton debris at the seafloor. To interpret the production versus deposition rates during the early and middle Miocene, proxies were used in conjunction with direct measurements of biogenic remains. By determining the concentrations of biogenically produced barium (bio-Ba), which is less affected by degradation, it is evident that the mass of Corg produced was much greater than that preserved in the sediments. We observed higher deposition of bio-Ba and bio- SiO₂ as the site was transported over the equatorial divergence by plate tectonics, as expected. In contrast, CaCO₃, accumulation was low in the divergence region, and coincides with a dissolution event known from other site studies in the equatorial Pacific. The pattern of uranium deposition resembles CaCO₃ and Corg, and average U concentrations suggest that it was primarily deposited as a trace element in the shell material of biogenic carbonate. Corg also resembles CaCO₃ and appears to represent primarily a dissolution signal. Total uranium analysis proved to be a useful proxy for Corg and CaCO₃ preservation, and analysis of detrital thorium (²³²Th) concentration suggests very limited terrigenous clay input. Comparison of the different proxies reveals carbonate preservation events, changes in Corg preservation, and changes in deposition as DSDP Site 574 migrated northwesterly across the equator.
158

Electrical Resistivity Imaging for Unknown Bridge Foundation Depth Determination

Arjwech, Rungroj 2011 December 1900 (has links)
Unknown bridge foundations pose a significant safety risk due to stream scour and erosion. Records from older structures may be non-existent, incomplete, or incorrect. Nondestructive and inexpensive geophysical methods have been identified as suitable to investigate unknown bridge foundations. The objective of the present study is to apply advanced 2D electrical resistivity imaging (ERI) in order to identify depth of unknown bridge foundations. A survey procedure is carried out in mixed terrain water and land environments with rough topography. A conventional resistivity survey procedure is used with the electrodes installed on the stream banks. However, some electrodes must be adapted for underwater use. Tests were conducted in one laboratory experimentation and at five field experimentations located at three roadway bridges, a geotechnical test site, and a railway bridge. The first experimentation was at the bridges with the smallest foundations, later working up in size to larger drilled shafts and spread footings. Both known to unknown foundations were investigated. The geotechnical test site is used as an experimental site for 2D and 3D ERI. The data acquisition is carried out along 2D profile with a linear array in the dipole-dipole configuration. The data collections have been carried out using electrodes deployed directly across smaller foundations. Electrodes are deployed in proximity to larger foundations to image them from the side. The 2D ERI can detect the presence of a bridge foundation but is unable to resolve its precise shape and depth. Increasing the spatial extent of the foundation permits better image of its shape and depth. Using electrode < 1 m to detect a slender foundation < 1 m in diameter is not feasible. The 2D ERI method that has been widely used for land surface surveys presently can be adapted effectively in water-covered environments. The method is the most appropriate geophysical method for determination of unknown bridge foundations. Fully 3D ERI method at bridge sites is labor intensive, time consuming, and does not add enough value over 2D ERI to make it worthwhile.
159

Hydrographic Characteristics of the Love River

Tsai, Jr-wei 16 September 2004 (has links)
In this study, twenty-seven experiments of transport and hydrographic observations were conducted at 9 bridges along the Love River during the period between 2001/12/20 and 2003/9/10. In each experiment repeated measurements were made at each bridge every two hours for a total period of 12 hours. An additional experiment (the 28th experiment) was conducted at 2004/6/16 in the Chihsien Bridge which consists of continuous measurements of velocity, depth and turbidity with a total length of 27 hours. Our results indicate that the Love River is influenced by the incoming tides from the river mouth up to the Dingxin Bridge. The tidal range is approximately 1m during spring tides (10cm during neap tides) at river mouth. The velocity at the Chihsien Bridge has a high frequency variation with a period of approximately 1 hour and amplitude of 20 cm/s during the 28th experiment. Salinity variations are in phase with tides, while turbidity and tides are out of phase. Harmonic analysis of depth, velocity, salinity and turbidity data all indicate that K1 is the principal tidal constituent followed by M2. River transport in the lower estuary is mainly comprised of two parts: tide and river discharge. The tidal induced transport is estimated to be ¡Ó30 CMS and net river discharge is about 1~9 CMS. The upper estuary is affected by two transport mechanisms: agricultural runoff and rain precipitation. After analyzing the measurement results, the transport of the upper branches is estimated to be 0~0.5 CMS during dry seasons and 1~5 CMS during rainy seasons. The agricultural transport reaches its maximum value in January with an estimated rate of 1~2.8 CMS. For the upper branches of Love River, the ratio£\between the hydraulic depth D and hydraulic radius R is found to reach a constant value of 0.9~1.0 when the transport Q is less than 2CMS, and£\is 0.8~0.9 when Q is greater than 2 CMS. The relationship between Q and the section factor TaDb, where T is the channel width, is found to be TD5/3=7.171Q (Dingxin Bridge) and TD5/3=0.744Q (Hougang Bridge) based on Manning formula. Finally, the relationship between Q and D is found to be D=1.811Q0.2981 (Longxin bridge) and D=0.266Q0.256 (Hougang Bridge).
160

Study of Selection Procedure on Critical Modules of ERP for Taiwan Flat Steel Industry.

Lin, Chih-yi 10 June 2005 (has links)
There are a lot of complicated factors affecting the success of an Enterprise Resources Planning (ERP) project. These factors can be divided into controllable and uncontrollable ones. For instance, the schedule management, the allocating resources and the method of implementation are controllable. Once the ERP system and vendor are decided and unchangeable, the ERP itself will become the uncontrollable factor. Unless we abandon the ERP project and restart it again, otherwise the project must proceed and go on continuously. If ERP system is suitable for the enterprise, the degree of customization can be reduced. However the customization is the most significant factor that delays implementation schedule and increase more cost than budget. If the functions of ERP system do not fit the requirements of an enterprise it will cause the extreme large degree of customization. To select an adequate ERP system fit for company¡¦s functions is the first step towards the success of ERP project, and further improve the performances of enterprise with ERP system. The most important key is to choose an industry-specified ERP system and to implement it actively, but little research focuses on it. This study emphasizes the concept of an industry-specified ERP system, using flat steel industry as the research object and considering the process of implementation of ERP system. We take account of the major dimensions and critical modules of ERP system during the selection period. This paper expects to provide flat steel industry an objective method for selection of critical functions and needed modules. It can help flat steel industry choose the most applicable ERP system effectively, and increase the probability to implement ERP successfully. Finally, some suggestions were provided for ERP system vendors to consider the requirements of different types of industries, especially the flat steel industry.

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