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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.
31

Design and Development of a Self-humidifying and Preventing Performance Decay Portable HFC Stack

Su, Hsun-Hung 05 September 2011 (has links)
In this thesis, a PEMFC stack, which can be self-humidification of passive portable hydrogen fuel cell, will be developed. The stack is developed for portable applications, so the structure of the stack is simplified as possible as we can. As the cathode directly exposed under the atmosphere, so in a long time, the membrane easily lead to excessive evaporation of water, so that performance degradation. The traditional humidifier is more complex applications are not suitable for portable, so this thesis stack developed by the use of cotton capillarity, the water from the tanks transferred to the membrane, and then by cotton and a good touch to the membrane humidifier effect, this structure without an increase in large equipment, in line with the principles of portability. The PEMFC stack is made with carbon fiber bunches for current collectors and two 8-cell banded-type MEAs, the stack can develop a high voltage by serially connecting outside of the reaction chamber. 16-cell in series when the current density is greater than 110mA/cm2, use humidification to avoid long time operation, due to water cause a voltage drop. Humidification is not only to help transfer of hydrogen ions, and the role of a cooling stack, the cells temperature is too high will not cause transpiration rate of speed. Current density greater than 250mA/cm2, although humidity can still be effective, but insufficient humidification single cotton, one hour after, the voltage drop of about 20% longer cell performance, such as humidity will be no more have a more significant decline phenomenon, more cotton or additional external humidification humidifier can maintain a long-time stable operation. Therefore, the performance of the cells in order to avoid a recession, should pay attention to in a long time when working conditions and operating range.
32

none

Chen, Ho-hsiung 02 September 2009 (has links)
This paper aims to explore the impact of portable labor pension system on labor employment in Kaohsiung County after its implementation. Being an important industrial zone and there are numerous labor working here, Kaoshiung County deserves to serve as the target and area for this study. In this study, the in-depth interview approach was adopted, and the subjects of in-depth interviews included four (4) persons from the agencies under Kaohsiung County Government, one (1) person from Kaohsiung County Industrial Association, one (1) person from Confederation of Trade Union of Kaohsiung County, and five (5) persons from different enterprises. Although different opinions were obtained from the interview, we could conclude 10 key points from the study results as follows: 1. The labor mobility did not increase after implementation of the new labor pension system. Labors did not care about things that had not happened yet. What they cared about was whether they were able to continue their jobs or not. 2. The implementation of the new labor pension system did not cause any increase in business closedown. Actually, the contribution to labor pension fund occupied only a few percentage of the personnel cost, and the cost increased due to the new system would be reflected in the prices of products. 3. The implementation of the new labor pension system did not increase layoff of employees. Companies would not lay off their employees due to implementation of the new labor pension system. They would cope with the cost increased due to the new system by improving their equipment and working process and increasing the productivity. 4. The implementation of the new labor pension system did not cause any increase in labor-management disputes. In general, most labor disputes were caused by issues such as overdue wages payment, refusal to join in the labor insurance, application for certificate of involuntary turnover, or payment of severance pay. The dispute on new labor pension system was only a small issue in labor-management disputes. 5. After the implementation of new labor pension system, enterprises may not contribute to the pension fund according to regulations. Big enterprises are most likely to change their salary structure and welfare policies, while small businesses may directly deduct the pension fund from employees¡¦ salary. The costs increased due to the new system were usually deducted from other places. Labors do not have any access to the labor pension fund in substance. 6. The implementation of the new labor pension system did not cause any increase in enterprises¡¦ outsourcing operation. Enterprises would outsource their work for the need of projects or business. The purpose of outsourcing was to save operating cost instead of labor cost. 7. The implementation of the new labor pension system would increase the employment of dispatched workers because in such way enterprises would need not to contribute any money to the labor pension fund. 8. The implementation of the new labor pension system would increase the employment of temporary workers and contracted workers. In order to reduce labor cost, enterprises would tend to employ temporary workers and contracted workers. Labors were also willing to be hired as temporary workers and contracted workers if enterprises agree to contribute to the labor pension monthly for them. 9. The implementation of the new labor pension system did not cause any increase in employment of middle-aged labors. Employers would not hire middle-aged labors just for saving expenses for labor pension fund under the new system. The reason why they did not consider hiring the middle-aged labors was because of their poor physical strength and productivity. 10. The implementation of the new labor pension system did not increase unemployment. Enterprises would not reduce employment if they have to speed up their work. The implementation of the new system did not directly cause an impact of unemployment on labors, but it did influence the enterprises¡¦ willingness in employment of temporary workers and contracted workers. They would rather to hire the dispatched workers and thus indirectly lead to a condition of short-term unemployment.
33

Journeys of Our Ancestors: Conservation Science Approaches to the Analysis of Cultural Material

O'Grady, Caitlin Rose January 2009 (has links)
The application and use of non-destructive portable x-ray fluorescence (XRF) analysis is a critical tool in the preservation and interpretation of cultural material. Portable XRF instrumentation produce elemental compositional data that is used to reconstruct current artifact composition, which can be related to materials and methods of manufacture, technological practice, as well as object condition and presence of corrosion surfaces. Portable XRF analysis is used to assess a variety of material classes utilized in artifact manufacture. The dissertation research is based on a series of three case studies that represent typical groups of material culture commonly encountered in conservation and conservation science research.Conservators and conservation scientists frequently undertake analysis and interpretation of disparate groups of materials. Often, these objects are tied together by research questions or themes directed by outside influences including preservation issues requiring action; curatorial research interests; museum exhibition programs; as well as many other cultural heritage stakeholders. To this end, both non-destructive and destructive tools that provide measurements of interest play critical roles in analysis. The case studies have been designed to answer common compositional questions relating to (a) bulk analysis of Chinese coins, (b) characterization of Southwestern ceramic colorants, and, (c) chemical examination of post-depositional manganese dioxide accretions occurring on archaeological ceramic materials. They evaluate the value of data produced using effectiveness of non-destructive portable XRF analysis for the interpretation of archaeological materials. The case studies provide a template for the development of conservation science research, predicated on object preservation, which produce meaningful data for the interpretation and conservation of the analyzed archaeological artifacts. Portable XRF provides useful data that is used to successfully interpret archaeological materials through (a) classification of metal alloys that can be related to published coin data, (b) identification of ceramic colorants and production technologies, and, (c) characterization of post-depositional product composition when used with established visual typologies.
34

A PORTABLE MONITOR FOR THE MEASUREMENT OF PERIODIC LIMB MOVEMENTS IN RESTLESS LEGS SYNDROME: VALIDITY AND RELIABILITY

O'Donovan, MARY 07 September 2012 (has links)
Purpose: A key objective feature in Restless Legs Syndrome (RLS) is the presence of Periodic Limb Movements (PLMs). The gold standard for documenting PLMs is through polysomnogram (PSG), an overnight sleep study in a sleep laboratory, which is expensive and often inaccessible. This work explored the ability of a portable sleep monitor (PM) to reliably record surface EMG signals, to reliably record limb movements overnight in comparison with PSG, and examined intra- and inter-rater reliability for scoring the PM recordings. Methods: The PM’s surface EMG channel was tested against a standard EMG amplifier by recording bilateral tibialis anterior muscle activity in five healthy participants. It was also tested for recording PLMs simultaneously with polysomnography at Kingston General Hospital with 40 participants referred for screening of sleep disorders. PLMs were scored using standard criteria according to the American Academy of Sleep Medicine Scoring Manual (2007) Analyses: Comparison between the two methods of surface EMG recording was through counts of muscle activity bursts. Comparison of overnight PLM counts was through t-test, Pearson’s r, Intraclass Correlation Coefficient (ICC) and Bland-Altman plots. Intra-rater reliability and inter-rater reliability between two analysts was examined by ICC. Results: Examination of the PM surface EMG recordings demonstrated an exact match of muscle activity counts between the PM and standard EMG recordings. In the PSG study, mean difference between the two PLMI values was +4.8 ± 11.1, t (34) = 2.1, p = 0.04, which was statistically significant and demonstrated systematic over-reporting by the portable monitor. The two PLMI values were strongly correlated, giving a Pearson’s r = .87, p < 0.001. ICC for absolute agreement was 0.87, (95% CI, 0.76 – 0.93), p < 0.001. Bland-Altman analysis gave 95% limits of agreement between the two PLM Indices as +27.9 (95% CI +33.0 to 20.2) to – 19.3 (95%CI -10.6 to -23.4). Conclusions: These data suggest there may be sufficient agreement between PLMI collected by PM and polysomnography to support the use of the PM for measuring PLMs. Further testing should address test retest reliability and examine the performance of the PM in a wider patient population. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2012-08-24 16:40:03.381
35

Development and investigation of a small, high aspect ratio, two-stroke engine

Disseau, Mael Leo David Soliman 08 1900 (has links)
No description available.
36

Using hypermedia in education : a case study using Animated Dissection of Anatomy for Medicine (ADAM)

Ruby, Laconya Dannet 12 1900 (has links)
No description available.
37

An eclectic solution to small screen interaction

Stamper, Timothy K. 05 1900 (has links)
No description available.
38

Inflatable antennas for portable direct satellite communication

Mathers, Naomi, naomi.mathers@vssec.vic.edu.au January 2010 (has links)
Satellite-based communication system can provide access to voice, data, video and internet transmission that is independent of terrestrial infrastructure. This is particularly important in disaster response situations and military maneuvers where mobile personnel need to maintain direct contact with each other and the central control. One of the factors that currently limits the effectiveness and practicality of these systems is portability. These systems require lightweight equipment that can be quickly and easily deployed and operated in a variety of environments. Parabolic dish antennas are the only antennas capable of providing the high gain required for direct satellite communication but their size and weight severely limit their portability and hence their use for portable direct satellite communication. Inflatable structures have been used in the space environment to overcome the limitations of launch vehicle size and weight restrictions. They are constru cted from thin film, or gossamer materials, and use internal pressure to maintain their shape. Inflatable structures are lightweight, have a low stowed volume and a high packing efficiency. It is proposed that this type of structure can be used to produce an inflatable parabolic dish antenna that can operate under terrestrial conditions to overcome the limits on portability for land-based communication. This thesis presents a design for a parabolic dish antenna and conical feed horn constructed entirely from polyester thin film. To further reduce the weight and stowed volume of the antenna the conical horn is fed by a microstrip patch. The performance of the components and their ability to operate under terrestrial conditions are assessed by comparing the results to those of an identical rigid system.
39

The application of the systems engineering process to the development of a global communications system using portable phones /

Jones, Stephen J. January 1992 (has links)
Project Report (M. Eng.)--Virginia Polytechnic Institute and State University. M.S. 1992. / Vita. Abstract. Includes bibliographical references (leaves 125-127). Also available via the Internet.
40

Security for PDAs

Huang, Jianyong. January 2004 (has links)
Thesis (M.Comp.Sc.)--University of Wollongong, 2004. / Typescript. Includes bibliographical references: p. 68-73.

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