Increasing the catalyst utilization is one way to improve the performance of a fuel cell. In this study, the hydrophobic pillared micro structures (HPMS) is used to increase the oxygen/ catalyst layer interface and thereby raise the performance by about 40%. By using the HPMS of a large size, the performance is improved by around 20%, which is just the same as the increment of the contact surface between oxygen and catalyst layer. By halving the loading of the small HPMS and thus increasing the contact surface between oxygen and the catalyst layer by half of the previous amount, the performance increase is also halved. These experimental results indicate that the main reaction zone is near the surface between oxygen and the catalyst layer. Consequently, there is no obvious decrement in the performance when the Pt loading of cathode is halved, just as the experimental results indicated. As a result, the utilization of catalyst is raised substantially.

Nowadays, the common method to make an alignment layer of liquid crystal display is rubbing Polyimide (P.I.) thin film, Unfortunately, the rubbing method will reduce the yield of LCDs because of the particles, electrons, etc. created during rubbing on the surface of PI film. therefore many effort have been made to develop the non-contacting method such as photo alignment, plasma alignment, etc. This research focus on the non-contacting method, we hope it will reduce many pollution compared to rubbing alignment. Comparing with PI, polydimethylsiloxane (PDMS) possess higher transparency, batter stability in thermal and chemical, and lower surface free energy about 19 mJ/m^2. Due to the low surface free energy, PDMS can be used as a vertical alignment layer without any surface treatment. Methyl Red (MR) PDMS mixed with PDMS will be used as an alignment layer in this experiment. And the rod-like azo-dye will change its molecular to rotate because the absorption of linear polarized light. By changing the s MR to rotate, we can obtain a micro groove structure on PDMS surface and control the direction of liquid crystals further. Xenon lamp(100nm-1200nm) and the ultraviolet ray lamp (300-500nm) were used in this experiment for thin film. Samples were exposure with different incident angle and intensity of light, respectively, and discussed with different temperature as a factor. According to atomic force microscope ( AFM ) result, we can obtain a PDMS surface with micro groove structure by using Xe lamp and ultraviolet ray, and we can observe the changing tilt angle of liquid crystals by polarized optical microscope (POM).

abstract: As a prelude to a study on the post-liquefaction properties and structure of soil, an investigation of ground freezing as an undisturbed sampling technique was conducted to investigate the ability of this sampling technique to preserve soil structure and properties. Freezing the ground is widely regarded as an appropriate technique to recover undisturbed samples of saturated cohesionless soil for laboratory testing, despite the fact that water increases in volume when frozen. The explanation generally given for the preservation of soil structure using the freezing technique was that, as long as the freezing front advanced uni-directionally, the expanding pore water is expelled ahead of the freezing front as the front advances. However, a literature review on the transition of water to ice shows that the volume of ice expands approximately nine percent after freezing, bringing into question the hypothesized mechanism and the ability of a frozen and then thawed specimen to retain the properties and structure of the soil in situ. Bench-top models were created by pluviation of sand. The soil in the model was then saturated and subsequently frozen. Freezing was accomplished using a pan filled with alcohol and dry ice placed on the surface of the sand layer to induce a unidirectional freezing front in the sample container. Coring was used to recover frozen samples from model containers. Recovered cores were then placed in a triaxial cell, thawed, and subjected to consolidated undrained loading. The stress-strain-strength behavior of the thawed cores was compared to the behavior of specimens created in a split mold by pluviation and then saturated and sheared without freezing and thawing. The laboratory testing provide insight to the impact of freezing and thawing on the properties of cohesionless soil. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2011

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To improve the value of enterprise, besides continuously utilizing vivacious creativities on new technology research a company also needs to quickly and constantly release new products and uplift added-values for all products. In the trend of globalization, corporations in Taiwan must meliorate their capability of product development project management to deal with the changing and dynamic environment thus create higher business profits and maintain some competitive advantages. For the optical micro-structure product development to succeed, business need to consider the external environment, internal resources and the characteristics of product development project in according with its initial resource and technical limitation then through systematic project management to accomplish it. This research adopts an architecture-oriented approach to strength the task of optical micro-structure product development project management. This research uses logic principle as a foundation, goes through (1) architecture-oriented construction approach, (2) non-architecture-oriented construction approach, and (3) comparison between architecture-oriented and non-architecture-oriented to confirm advantages of architecture-oriented optical micro-structure project management. With ¡§architecture hierarchy diagram", "structure element diagram", "structure element service diagram", "structure element connection diagram", "structure behavior coalescence diagram", and "interactive flow diagram", this thesis builds up an architecture-oriented optical micro-structure project management model, abbreviated as AOOMSPMM. Through AOOMSPMM, we are able to provide an effective construction approach hence reduce the failure risk and time cost when working on the optical micro-structure product development project management. Keywords: Optical Micro-Structure Product Development, Project Management Model, Architecture-Oriented

This dissertation contributes to the research in the applied market micro-structure field, aiming to investigate the impact of a specific article of the MiFID II enforced on the 3rd of January 2018: the so-called tick size regime. It is constituted by three papers that see in the market regulators and policy-makers their optimal target. The first paper evaluates the consequences of the new regulation on UK minor venues in terms of liquidity and price discovery and highlights minor unintended consequences in the implementation of the new grid. The second paper builds on these conclusions and promotes an alternative to ESMA grid, a recalibration of the tick size that might lead to a greater orderliness of UK order books. Thethirdpaperendogenouslyinvestigatesthebehaviourofthemarketparticipants in the time frame around the MiFID II enforcement, simulating liquidity breakdowns thus providing the regulators with new simple metrics to detect and monitor abnormal market participants interactions.

Les matériaux granulaires exhibe un spectre très large de propriétés constitutives, le long de chemins de chargement très divers. Développer des modèles constitutifs permettant de reproduire ces caractéristiques a demeuré un réel challenge scientifique au cours des dernières décennies. A cet égard, les approches multi-échelles constituent aujourd’hui une voie très prometteuse. Elles permettent de relier les propriétés macroscopiques à celles observées à l’échelle microscopique.Une investigation a été menée sur la base de simulations numériques discrètes (DEM)d’essais biaxiaux, afin d’identifier les caractéristiques micro-structurelles du matériau granulaire, la manière dont elles évoluent au cours d’un chemin de chargement, et le rôle qu’elles jouent dans l’émergence du comportement macroscopique. A l’échelle mésoscopique,le réseau de transmission de force (chaines de force) et les cellules définies parles vecteurs branches (meso-cycles) apparaissent jouer un rôle de première importance.Les meso-cycles, construits à partir du réseau de contact de l’assemblage, peuvent être caractérisés en fonction du nombre de cotés qu’ils contiennent (topologie). Leur influence sur le comportement volumique de l’échantillon est en effet étroitement liée à ce nombre de contact. En outre, leur interaction avec les chaines de force est également fortement dépendante de leur topologie. Ainsi, les cycles contenant 3 cotés (L3) participent activement à la stabilisation des chaines de force, alors que les cycles contenants au moins6 cotés (L6+) contribuent essentiellement au comportement dilatant de l’échantillon et à l’effondrement des chaines de force. Enfin, l’existence d’une méso-structure unique à l’état critique, au sein de la bande de cisaillement (rupture localisée) ou au sein de l’échantillon (rupture diffuse), est clairement démontrée.viii Sur la base de ces résultats, un modèle constitutif a été développé à partir du modèle H-directionnel (Nicot and Darve, 2011b). La structure du matériau granulaire est décrite par un assemblage d’hexagones (modélisant les cycles L6), orientés dans toutes les directions de l’espace. A partir d’opérations d’homogénéisation, les contraintes et les déformations incrémentales peuvent être reliées à l’échelle de l’assemblage, donnant lieu à un modèle de comportement dont la performance a pu être testée le long de chemins de chargements variés. / Granular materials exhibit a wide spectrum of constitutive features under various loading paths. Developing constitutive models which succeed to characterize these features has been challenging scientists for decades. A promising direction of achieving this can be the multi-scale approach. Through which the constitutive model is formulated in the way that relating material's macroscopic properties to their micro-scale essences, namely, corresponding micro-structure properties.To better characterize the micro-structure and formulate the relation between different scales, a comprehensive investigation have been carried out on the basis of numerical biaxial tests using 2D discrete element method (DEM), in order to ascertain the micro-structure characteristics of the granular material, the way they evolve versus loading and their corresponding rules in the macroscopic behaviors. In a meso-scale, intermediate between the single contact scale and the macro-scale, the force transmission network (force-chains) and area element enclosed by contacts branches (meso-loops) are highlighted in terms of their significant influences on material's macro-scale behavior. Meso-loops herein are tessellated from the whole area of the granular assembly by the contact branch network, and are subsequently categorized according to their side number.The development of meso-loops is observed to be intimately related to material's volumetric evolution, especially the plastic part. Then, the interaction between force-chains and meso-loops and its significance to the global volumetric behavior are revealed. Otherwise, in critical state, an identical meso-structure is found in the failure area of both localized and diffuse failure mode. Meso-loops with 3 sides (L3) appear to be indispensable for the force-chain stability, meanwhile, meso-loops with more than or equal to 6 sides (L6+) contribute much to the volume expansion and accelerate the force-chain buckling. The interplay between L3 and L6+ largely embody, or are representative of, the various mechanical performance of the granular material.A constitutive model has been developed by modifying the H-directional model. In this model, individual hexagons, representatives of L6+, construct the fabric as distributing along different directions in the space. Then multi-scale approach is then used to relate macroscopic properties from local ones, and eventually, to give the constitutive relation. This model is then validated in different loading paths, and eventually proved satisfying.

As the demand for green energy and fuel cells grows, more attention is drawn towards Solid Oxide Fuel Cells (SOFCs). Random and complex structure of composite electrodes and underlying electrochemical process has not been completely unveiled yet and further study is required to acquire more understanding. Modeling in this regard plays an important role as it pinpoints key parameters in optimum design of the cell without resorting to costly and uncertain experiments which might even lead to misinterpretations due to random nature of experimental data. The aim of this work is to develop a new rigorous model to study the structure performance relationship of (SOFC) composite electrodes. The work has been conducted in two phases, a two-dimensional continuous approach and three-dimensional discrete model. A new two-dimensional, geometrical model which captures the inhomogeneous nature of the location of electrochemical reactions based on random packing of electronic and ionic conducting particles has been developed. The results show that the concentration of oxygen inside the cathode in the two-dimensional model is not only a function of the electrode depth but also changes along the width of the electrode. Furthermore the effect of composition of the electrode on the length of three phase boundary (TPB) and total polarization resistance has been demonstrated. A parametric study of the effect of the conductivity of ionic conductor and diffusion coefficient on the performance of the electrode has been given. To make a more realistic analysis, a three-dimensional reconstruction of (SOFC) composite electrodes was developed to evaluate the performance and further investigate the effect of microstructure on the performance of electrodes. To enhance connectivity between particles and increase the length of TPB, sintering process is mimicked by enlarging particles to certain degree. Geometrical characteristics such as length of TBP and active contact area as well as porosity can easily be calculated using the current model. Electrochemical process is simulated using resistor-network model and complete Butler-Volmer equation is used to deal with charge-transfer process on TBP. The model shows that TPBs are not uniformly distributed across the electrode and location of TPBs as well as amount of electrochemical reaction is not homogeneous. Effects of particle size, electrode thickness, particle size ratio, electron and ion conductor conductivities and rate of electrochemical reaction on overall electrochemical performance of electrode are investigated. / Chemical Engineering

This study focused on analysis and experiment of hot extrusion of aluminum and magnesium alloys, an extrusion die with an inclination angle leads to non- uniform velocity distribution at the cross-section of the die, and results in different strain and strain rate distributions. This kind of design can make the grain size at the material surface smaller and get a material with larger surface hardness. This study aims to conduct hot extrusion with different die inclination angles, and obtain a material with gradient micro-structures. At first, die with different inclination angles are designed, and the temperature at the die exit and effective strain, effective strain rate distributions are discussed using the finite element analysis. At last, aluminum and magnesium extrusion experiments are conducted and the micro-structures of the materials are observed to understand the effects of the die inclination angles at 15 degrees on the grain size distribution and hardness test at the cross-section of the material. The grain size is about 17.2£gm at around center of the cross-section and hardness is about 68.2HV. The smallest grain size is 4.1£gm at the edge of the cross-section and the highest hardness is 83.8HV.

Abstract The conventional hydrophilic electrode used to spray the catalyst on the level-off carbon layer and the utilization of catalysts can only be reacted between the gas and the catalyst; however, the internal catalyst of the proton exchange membrane cannot be reacted. In order to increase the reaction of the catalyst, the hydrophobic pillared micro structures (HPMS) are made on the carbon layer, so that the gas can reach the catalyst in the internal membrane so that a reaction on large surface between the gas and the catalyst can be achieved. It is easier to build the gas channel in the internal HPMS than the structures of the carbon layer. As a result, more gas can be sent to the internal catalyst thus enlarging the reaction zone and more reactions between the gas and the catalyst is then achieved. The carbon powder is sprayed in the conventional HPMS in the deposition process. The HPMS are formed after the gravity process while the powder is passing the metal netmask and the manufacturing time is long. The experimental design uses electroforming to make the micro porous structure so that the hydrophobic carbon layer can be stamped thereby forming the HPMS. It has been proven that the time for the manufacturing process can be shortened if the micro structured metal template is applied. The micro structured metal template is used to stamp the small and large HPMS on the side electrode of the cathode, the stamping HPMS pressure was 500kg/cm2. With the same catalyst quantity the surface of the small HPMS was raised 63% and its performance was up to 55%; the surface of the large HPMS was raised 30% and its performance was up to 30%. The catalyst quantity of the cathode was reduced from 0.5mg/cm2 to 0.25 mg/cm2 and its performance remains the same. The experiment¡¦s results indicate that the reaction of the catalyst was only on the surface between the gas and the catalyst. Either small or large HPMS or after reducing the catalyst quantity can all raise the performance of the fuel cell as well as economize the catalyst. And by two kind of different size dimension microstructure metal template manufacture small or large HPMS, the electrode power density all may achieve 720mW/cm2 and 595mW/cm2.