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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.
331

The Effects of Using Alkali-Silica Reaction Affected Recycled Concrete Aggregate in Hot Mix Asphalt

Geiger, Brian James 2010 August 1900 (has links)
The effects of using alkali-silica reaction (ASR) affected recycled concrete aggregate (ASR-RCA) in hot mix asphalt (HMA) were investigated in this study. Dilatometer and modified beam tests were performed to determine the possibility of new ASR occurring in reactive aggregates within the HMA or re-expansion of existing gel. The Lottman test and micro-calorimeter were used to determine the moisture susceptibility of HMA made with ASR-RCA. A differential scanning calorimeter (DSC) with thermogravimetric analysis (TGA) was used to evaluate the drying of an artificial gel and x-ray diffraction (XRD) was used to check for the potential presence of gel in the filler fraction of the ASR-RCAs. Micro-deval and freeze-thaw tests were evaluated for their potential to indicate the presence of excess micro-cracks or ASR gel. Expansion testing indicated that both ASR-RCAs were still reactive with 0.5 N NaOH solution saturated with calcium hydroxide (CH) at 60 degrees C. Dilatometer testing of HMA specimens in NaOH CH solution at 60 degrees C indicated a reaction between the asphalt binder and the solution, but little, if any, ASR. The lack of expansion in the modified beam test supports the binder-solution interaction. However, dilatometer testing in deicer solution at the same temperature indicated that some ASR may have occurred along with the primary binder-solution interaction. The volume change characteristics associated with the binder-solution interaction with and without ASR was supported by the change in pH and alkali concentration of the test solution. DSC/TGA testing indicated that the artificial gel dehydrated at approximately 100 degrees C. XRD analysis of the filler indicated that some gel may have accumulated in this fraction. Moisture damage testing indicated good resistance to moisture damage by HMA mixtures made with ASR-RCA especially compared to a virgin siliceous aggregate. Micro-deval and freeze-thaw tests can detect the presence of micro-cracks due to ASR in ASR-RCAs as higher mass loss than the virgin aggregate. The potential distress mechanisms that may occur when using ASR-RCA in an HMA pavement were identified. Results obtained using accelerated laboratory conditions were extrapolated based on anticipated field conditions. Guidelines for the mitigation of potential distresses in HMA made with ASR-RCA are presented.
332

Prepainted galvanized steel sheet and color steel sheet in steel industry compete advantage to study-- Case Yiehphui Company Study

Wang, Chih-chiang 10 August 2005 (has links)
Along with science and technology gradually make progress, there is no distance between country. WTO world commerce cloggy eliminate, have no frontier's confine to make product and service that almost be obvious everywhere in the world. Under economic liberalization and internationalize affection, make enterprise management no longer confine to one area or single country. Economic globalization impact everywhere in the world. Iron and steel industry can¡¦t also avoid meeting severely impact and change. In 2002, because global economies gradually change better, lead to international steel market demand to grow up quickly. It is fourth season to reach the best. Price appears take on upspring, too. Due to every important manufacturer rob to buy materical each other in the world, appear steel materical demand to exceed supply. At the end of the year 2003, America, European union, mainland China cancel import restriction successively. At the beginning of the year 2004, price of freight, iron ore, coalmine, scrap steel (Steel ingredient) increases largely at the same time. Many countries ensure steel requirement materials at home, so steel importation tariff transfer fall successively. It makes strict confine measure gradually change to loose. Hot Rolled Galvanized Steel Sheet requires mean consumption to grows up 4.4% near five years in the world. Price also rise along with the price of Hot-Rolled Steel Coil is on raise at the same time. Steel market changes quickly like electronic product¡¦s life. Steel industry face structure change and reform management. In the world, all steel industry is toward competition and cooperative style. Industry internationalize brings manufacture and sales mode's changed. Industry protection policy already do not exist. With environment changed quickly, enterprise do the best increase management performance. It just be able to abidingly run and develop. The study chiefly use questionaire as interview style to get information and organize theoretical document to review and research. Let us know Hot Rolled Galvanized Steel Sheet and Prepainted Hot-Dip Zinc Coated Steel Sheet company how to develop in the world now. It is as Yiehphui company for example, explore Hot Rolled Galvanized Steel Sheet and Prepainted Hot-Dip Zinc Coated Steel Sheet industry how to take advantage of limited source and face industry environmental change to upgrade management technique. By industry internationalization working principles, make enterprise management risk asunders and create industry competition advantage. It becomes industry developmental reference. The study shows some conclusions as follows: 1. Materials source need stability and multiplication. It avoid confining provider but have no method to acquire advantaged negotiate. 2. International steel area integrated tendency have already formed. Major company become bigger and bigger can not avoid. Individual company should cooperation or tactic federation at home with same industry company, form area economy magnitude and debases competition pressure. 3. Push and import TPM management system and TSM work safe management system to healthy company operate constitution and attract elitist. 4. Global market runs for springboard as strengthen developmental technology, develop high affixation value product and new product use domain. It aggravates brand impression and difference product to used for seize more market area and market benefit.
333

An Explanation to Hot-Issue Anomaly of IPOs in Taiwan

Lu, Cheng-shou 26 January 2007 (has links)
ABSTRACT Ibbotson and Ritter (1995) indicate that there are three anomalies in IPO markets: IPO underpricing, IPO long-run underperformance, and hot-issue market. Contrary to most of the previous studies which focus on IPO underpricing or IPO long-run performance, this dissertation examines the existence of hot-issue phenomenon in Taiwan IPO markets. ¡§Hot-Issue anomaly¡¨ means that cycle exists in both the IPO volume and IPO underpricing. Consequently, issuers tend to issue new equity to the public when faced with high average initial returns of IPOs. Ritter (1984) argues that IPOs in hot markets experience higher initial returns. Moreover, young IPOs experience more underpricing in hot markets. A possible explanation for hot-issue phenomenon is the positive feedback hypothesis: market investors positively react to IPO underpricing. When investors earn initial returns from IPOs, they are more likely to subscribe to future IPOs leading to the fact that issuers tend to issue when previous IPOs are more underpriced. Hot-issue is considered as an anomaly because underpricing or initial return is referred as an indirect cost of issuance. Issuers should try to reduce the extent of underpricing to raise IPO proceeds. From the point of view of maximizing proceeds, previous studies fail to explain the hot-issue anomaly in IPO markets. Ibbotson, Sindelar, and Ritter (1994) show that IPO hot-issue phenomenon exists not only in U.S. market but also in Germany, South Korea, and U.K. markets. To make up this gap, this dissertation first tests if there exists hot-issue anomaly in Taiwan and then examines why hot-issue anomaly exists to provide an explanation to the anomaly. I find that IPO initial return leads IPO issuance. However, issuance of IPOs does not reduce the extent of underpricing of the followed up IPOs. I further show that IPO initial return is not related to the initial return of the followed up ones. The issuance of IPOs cannot be attributed to the information of initial returns of preceding IPOs. Rather, the market information between IPO filing date and IPO issuance date is the cause for the lead-lag relation between IPO initial return and IPO issuance. IPO offer price will fully reflect to the negative recent market return but simply partially to the recent positive market return. Most of the IPO initial return can be explained by the information revealed after offer price has been set implying that the offer price is set efficiently. The large amount of IPO volume following high IPO initial return can be attributed to the positive market reaction to the preceding IPOs instead of the filed IPO pricing of preceding IPOs. Our findings explain the hot-issue anomaly. During hot markets, investors¡¦ excess demand on IPOs leads to high initial returns of IPOs. Faced with investors¡¦ excess demand, issuers attempt to issue IPOs to take advantage of investors¡¦ sentiments to maximize IPO proceeds.
334

Investigation on Characteristics of Metal Halide Lamp

Soong, Ming-Jung 21 June 2000 (has links)
Abstract The metal halide lamp is one of high-intensity discharge lamps. It has many advantages such as good color rendering, high efficacy and a variety of color presentations. However, the problems of acoustic resonance, a long transition period of cold starting, and an extremely high ignition voltage for hot restarting should be overcome. The investigation of the thesis is focused on the electrical characteristics of the metal halide lamp operating at high-frequency. Included are the acoustic resonance, starting transient and steady state operation. Various ballast circuits incorporating with ignitors are designed to drive several 70-W metal halide lamps. The operating frequency ranges with acoustic resonance, the ignition voltages for both cold starting and hot restarting, the transition period, the dimming performance, and the lamp equivalent resistance during the lamp life are measured and analyzed. Based on the investigated results, a useful guideline can be provided for the operation and design of the electronic ballast for metal halide lamps. Key words : Metal halide lamp, electronic ballast, acoustic resonance, hot restarting.
335

A Microstructure Study of Hot-pressed Pb(Mg1/3Nb2/3)O3 Ceramics

Tsai, Tsung-Fu 11 July 2000 (has links)
none
336

On the Study of Proton Exchange Membrane Fuel Cell¡XThe Fabrication and Performance Analysis of MEA

Leu, Chun-Ei 11 July 2000 (has links)
This research is to develop procedures on the fabrication of membrane electrode assembly (MEA), which is the heart of the Proton Exchange Membrane Fuel Cell. Sensitivity studies of the manipulated variable, such as pressure, temperature, and time, in the hot press process, which is adopted in the assembling on the performance of the MEA are also performed. The developed products on the cleaning of membrane as well as the hot press of MEA have been verified through many experiments. The tests of the MEA¡¦s thus produced reveal that temperature and pressure in hot press process have significant influence on MEA performance. Both have to be kept in a suitable range. Optimal operating conditions in the hot press process may be achieved by conducting more experiments and a detail understanding on the internal structure variation of membrane under high pressure and temperature condition.
337

Simulation and Analysis of Feedforward Automatic Gauge Control for a Hot Strip Finishing Mill

Chen, Po-Tsang 03 July 2002 (has links)
Recently, the accuracy of hot strip gage is strictly demanded, and the strip thickness becomes the most important quality in hot strip rolling. It is well known that the accuracy of final strip thickness in the hot strip mill depends on the gage control performance at each stand. In order to improve the quality of the hot strip gage and reduce the strip thickness deviation , the Automatic Gage Control(A.G.C) system now is widely used in modern hot strip mills of the world. In this paper, the principle of feedforward control strategy in the AGC system is discussed and it¡¦s control performance is deeply analyzed. Besides, based on the study of comprehensively mathematical model and the establishment of simulator, the mathematical analysis and the simulation result can clarify the influence of the control system on strip thickness.
338

Two Studies in the Stability of Taiwan Listed Stock Statistics-The Application of Nonparametric Method

Chuang, Ching-Chi 11 July 2002 (has links)
none
339

An analysis of maximum residential energy-efficiency in hot and humid climates

Malhotra, Mini 12 April 2006 (has links)
Energy-efficient building design involves minimizing the energy use and optimizing the performance of individual systems and components of the building. The benefits of energyefficient design, in the residential sector, are direct and tangible, provided that design strategies with a substantial combined energy and cost-saving potential are adopted. Many studies have been performed to evaluate the energy-saving potential and the costeffectiveness of various design options, and to identify conditions for optimizing the performance of building systems and components. The results of these studies, published in various resources, were analyzed discretely using different techniques, and were reported using different bases for comparison. Considering the complex interaction of, and energy flows through various building components, it is difficult to directly compare/combine the results from various studies to determine the energy-saving potential of combination of strategies, and to select an appropriate set of strategies for making design decisions. Therefore, this thesis develops a comprehensive survey and analysis of energy-efficient design strategies and their energy-saving potential, in isolation as well as in combination, using a DOE-2 simulation model of a prototype house in the hot and humid climate of Houston, Texas. Optimized strategies that included building configuration, materials/ assembly for building envelop components, and efficient mechanical and electrical systems, equipment and appliances, were applied in combination that could minimize the annual energy use. Application of these strategies is expected to allow downsizing systems and equipment and to confirm their operation at their rated performance, resulting in additional installation and operation cost savings. The study is concluded by outlining the procedures for selecting optimized set of strategies, and by developing guidelines for achieving maximum energy-efficiency in singlefamily detached houses in hot and humid climates. Thus, this study will facilitate the selection of energy-saving measures for their individual or combined application for developing energyefficient residences in hot and humid climates.
340

Probabilistic analysis of air void structure and its relationship to permeability and moisture damage of hot mix asphalt

Castelblanco Torres, Adhara 12 April 2006 (has links)
The permeability of hot mix asphalt (HMA) is of special interest to engineers and researchers due to the effects that water has on asphalt pavement performance. Significant research has been done to study HMA permeability. However, most of the studies primarily focused on relating permeability to the average percent air voids in the mix. Such relationships cannot predict permeability accurately due to the different distributions of air void structures at a given average percent of air voids. Air void distribution is a function of many factors such as mix design, compaction method, and aggregate properties. Recent advances in X-ray computed tomography and image analysis techniques offer a unique opportunity to better quantify the air void structure and, consequently, predict HMA permeability. This study is focused on portraying permeability as a function of air void size distribution by using a probabilistic approach that was previously developed by Garcia Bengochea for soils. This approach expresses permeability as a function of the probability density function (pdf) of the air void size distribution. Equations are derived in this thesis to describe this relationship for laboratory specimens compacted using the linear kneading compactor (LKC) and Superave^TM gyratory compactor (SGC) as well as for field cores (labeled as MS). A good correlation exists between permeability and the pdf of the air voids that formed the flow paths (i.e. connected voids). The relationship between moisture damage, air void structure, and cohesive and adhesive bond energy is also investigated in this study. Moisture damage is evaluated by monitoring changes in mechanical properties due to moisture conditioning. The influence of air void structure on pore pressure is studied using a recently developed program at Texas A&M University that simulates fluid flow and pore pressure in a porous medium. The surface free energy of the aggregates and asphalt are calculated from laboratory measurements using the Universal Sorption Device (USD) and the Wilhelmy Plate method, respectively, in order to test the compatibility of the aggregates with the asphalt in the presence of water.

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