Several disadvantages in general unipolar/bipolar plates are that cost is expensive, weight is heavy and the volume is large. The high compressing pressure is also necessary to reduce the contact resistance in making up a fuel cell stack. Therefore, it is difficult in making use general unipolar/bipolar plates to portable fuel cells. With a new heterogeneous carbon fiber bipolar plate, pumpless and air-breathing design and in cooperating with a special MEA, a portable fuel cell stacks developed in our lab have made portable applications to be possible. The structure of the DMFC stack made with the new carbon fiber bipolar plate is much more simple and weight-light than the other designs. The three portable DMFC stacks flat type, cylinder type (I), and cylinder type (II) are developed in series in our lab. The methanol solution can be stored directly in the flow channel of the anode, and does not need the extra auxiliary equipment, so it easy to apply to the portable fuel cell. The developed portable DMFC of cylinder type (II), weight is only 20g, volume is 30cm3, and the fuel stored capacity is 7.5ml. In the flat type DMFC, In anode Pt-Ru loading 3 mg/cm2, and cathode Pt loading 1 mg/cm2, methanol concentration 3 M, pumpless, air-breathing, and room temperature, the largest of output power density of the fuel cell can reach 5.27 mW/cm2, and the total power can reach 71 mW. The weight of DMFC of cylinder type (II) is far lower than DMFC of flat type in addition, so its power density 1.33mW/g is about 1.68 times of flat type 0.79 mW/g.

In this thesis the experimental method is used to study the characteristics of a DMFC when a heterogeneous carbon fiber bipolar plate is applied to it. The first main study is about the effect of the different structures of the carbon fiber bunch on the fuel cell performance. Additionally, a high temperature hot-pressing process is performed to change the inner molecular structure so that the hydrogen ion can be blocked to avoid the lateral migration between two adjacent cells. Finally, the two techniques are applied to make our new portable DMFC stack. The bipolar plates with the sawtooth or non-sawtooth carbon fiber bunches have been used in making our DMFC stack. The experimental results display that the performances of the two structures both are better than the traditional graphite bipolar plate. However, the performance of DMFC with the sawtooth bipolar plate is much better than that without sawtooth, especially in high current density. When carbon fiber bunches with sawtooth use at anode and cathode of bipolar plates, the performance can be enhanced and its power density 27.6% higher than that without sawtooth. During our study we also found that part of hydrogen ions can laterally migrate to its adjacent cathode and do not directly cross to its opposite cathode, when the banded type MEA are used to multiple cell stack. Therefore, the performance cannot be performed well due to this type ion transfer. In order to block the lateral migration, the narrow area of the membrane between two adjacent electrodes is pressed with a high temperature hot-pressing device. After a short time hot-press between two adjacent electrodes, the hydrogenion migration phenomenon reduced, and the performance had been improved about 10% higher than that without hot-press. Finally, a double layer 2x6-cell flat type DMFC is made. This 12-cell stack is composed of each electrode area 0.5x5cm2, two sheets of membrane for 6-cell using Nafion 117, the anode catalyst Pt-Ru loading 4mg/cm2, and cathode catalyst Pt loading 4mg/cm2, the methanol concentration 3M, air-breathing, and operating in room temperature. The output power of the cell can reach an average power density 8.0mW/cm2 and total power 240mW with our handmade stack. If the performance of each fuel cell is more uniform, we expect that total power can reach 480 mW. The power level should be satisfied for any kind mobile phone.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

published_or_final_version / Architecture / Master / Master of Architecture

This thesis investigates strategies for the portable classroom as a way of envisioning a new model for elementary schools in the region of Durham, Ontario. The portable and the school configuration is informed by a set of rules determined by site and program, making each school building unique and suited for its particular context. Geometry and play are at the core of how children learn, and the architecture will implicitly and explicitly engage this sense of play and learning. The pieces making up the modules have an aesthetic similar to Lego and K’nex toys, which immediately engages the childrens’ imagination and understanding, creating both a playful and engaging environment for learning. The strategy also brings together a variety of geometric pieces that form different classroom types and which can reconfigure for different rooms and uses. As such, the students may understand how the modules stack and stagger to create unique interstitial spaces for the public and for informal learning. These modules can be reconfigured using interior components that create a variety of smaller environments within the larger classrooms. As well as for expansion and contraction of school populations, these components could be recycled for use by other schools with growing populations. Thus, changing the role of the portable into a malleable, moveable aggregate, and making it easier and therefore economical to add, transform and subtract classrooms and learning spaces, school buildings come to life and change along with their setting.

Les technologies de l’information et des communications (TIC) sont de plus en plus utilisées dans les écoles canadiennes. Lorsque présentes en nombre important, comme dans le cas d’un déploiement massif d’ordinateurs portables en salle de classe, les enseignants nécessitent un appui. Le Conseil scolaire francophone (CSF) de la Colombie-Britannique a effectué un tel déploiement et s’est allié d’une équipe de cyberpédagogues afin d’aider les enseignants dans leur tâche d’intégration des technologies. Ce travail de recherche présente une approche méthodologique mixte à dominante qualitative et est structuré selon quatre questions de recherche qui nous permettent (1) de comprendre le rôle des cyberpédagogues, (2) les changements apportés par l’implantation du postes des cyberpédagogues, (3) les formations offertes aux enseignants et (4) le soutien technique lié aux TIC. Les questionnaires distribués aux deux groupes de répondants (26 enseignants et 12 cyberpédagogues) nous ont permis de constater des opinions très partagées entre les deux groupes. Par contre, la majorité des répondants s’entendent sur la nécessité des cyberpédagogues ainsi que le besoin de modifier leur rôle. La formation continue semble essentielle, mais serait un point à améliorer selon les enseignants (et plusieurs cyberpédagogues).

Les technologies de l’information et des communications (TIC) sont de plus en plus utilisées dans les écoles canadiennes. Lorsque présentes en nombre important, comme dans le cas d’un déploiement massif d’ordinateurs portables en salle de classe, les enseignants nécessitent un appui. Le Conseil scolaire francophone (CSF) de la Colombie-Britannique a effectué un tel déploiement et s’est allié d’une équipe de cyberpédagogues afin d’aider les enseignants dans leur tâche d’intégration des technologies. Ce travail de recherche présente une approche méthodologique mixte à dominante qualitative et est structuré selon quatre questions de recherche qui nous permettent (1) de comprendre le rôle des cyberpédagogues, (2) les changements apportés par l’implantation du postes des cyberpédagogues, (3) les formations offertes aux enseignants et (4) le soutien technique lié aux TIC. Les questionnaires distribués aux deux groupes de répondants (26 enseignants et 12 cyberpédagogues) nous ont permis de constater des opinions très partagées entre les deux groupes. Par contre, la majorité des répondants s’entendent sur la nécessité des cyberpédagogues ainsi que le besoin de modifier leur rôle. La formation continue semble essentielle, mais serait un point à améliorer selon les enseignants (et plusieurs cyberpédagogues).

This research aims to test the hypothesis that portable art objects and ornaments were used to create and maintain social networks between groups of hunter-gatherers coping with climatic insecurity. This is tested through the materials used to produce such objects. The results of tests indicate that the movement of objects of portable art and ornaments did not correlate with climatic values such as precise temperature and variance of temperature, which goes against the assumptions of the main hypothesis mentioned above. However, the variation in the production of these objects correlates well with broad climatic changes and with demographic events. This suggests that portable art objects and ornaments might have been used to a certain extent to help facilitate the population movements that were themselves affected by climate change. / Graduate

Needle trap device (NTD) is a technique that is useful for a wide variety of applications involving the sample preparation of compounds with a wide range of chemico-physico properties, and varying volatilities. A newly designed NTD that improves the performance relative to previous NTD designs is simple to produce is developed. The NTD utilizes a side-hole needle with a modified tip to improve the sealing between the NTD and narrow neck liner of the GC injector, thereby increasing the desorption efficiency. The slurry packing method was applied, evaluated, and NTDs prepared by this method were compared to NTDs prepared using the vacuum aspiration method. NTD geometries including blunt tip with a side-hole needle, tapered tip with side-hole needle, dome tapered tip with side-hole, sliding tip with side-hole and blunt tip with no side-hole needle (expanded desorptive flow) were prepared and evaluated. Sampling performance and desorption efficiency were investigated using automated headspace extraction of benzene, toluene, ethylbenzene, p¬-xylene (BTEX), anthracene and pyrene. The tapered tip and sliding tip NTDs were found to have increased desorption efficiency. SPME and NTDs are valuable sample preparation tools for on-site analysis. Combining both extraction techniques allows for the differentiation of free and particle-bound compounds in a sample matrix. Portable GC/MS instrumentation can achieve fast separation, identification, and quantitation of samples prepared by the above techniques on-site without the need for transport to the laboratory. This minimizes the effects of volatiles lost and sample degradation during storage time. Here, SPME and tapered tip NTDs combined with portable GC/MS are used to investigate free and total emissions of BTEX and select PAHs from gasoline and diesel exhaust. Using the above optimized technologies, cigarette smoke in a smoking area where people were actively smoking and inside a smoker’s car were also investigated. Target contaminants were found in the investigated matrices at ng/mL levels.

Thesis (M.F.A.)--Rochester Institute of Technology, 1993. / Typescript. Includes bibliographical references (leaves [49]-[52]).