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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.
201

Cultivo submerso de Aspergillus empregando óleos vegetais visando a síntese de lipases para aplicação industrial. /

Tacin, Mariana Vendrasco. January 2018 (has links)
Orientador: Valéria de Carvalho Santos Ebinuma / Coorientador: Ariela Veloso de Paula / Coorientador no exterior: Jose M. Palomo / Banca: Tales Alexandre da Costa e Silva / Banca: Marcdelo Chuei Matsudo / Banca: Fernando Masarin / Banca: Ana Lúcia Martiniano Nasser / Resumo: As lipases são enzimas amplamente aplicadas em processos industriais. Sua obtenção por fungos filamentosos apresenta algumas vantagens em relação às outras fontes e por isso estudos de incremento de sua produção vêm sendo realizados. Aliado ao processo de obtenção, técnicas de imobilização de enzimas podem melhorar sua estabilidade em relação à temperatura e pH, e diminuir custos associados à sua aplicação devido à possibilidade de reaproveitamento da enzima imobilizada nos processos biocatalíticos. Objetivo: este trabalho teve como objetivo estudar a produção de lipases pela cepa Aspergillus sp. DPUA 1727, a imobilização da referida enzima em suporte octil-sepharose, sua caracterização na forma livre e imobilizada e a aplicação da enzima imobilizada na obtenção de ésteres. Métodos: a produção da enzima foi realizada por 96 horas em cultivo submerso, avaliando-se diferentes fontes de carbono (óleos de soja, oliva, semente de uva e de algodão) como substratos indutores da produção enzimática. Posteriormente, estudou-se a imobilização da enzima em suporte octil-sepharose® por adsorção através de interação hidrofóbica, após o meio fermentado ter sido submetido à 4 ciclos de extração do óleo residual da fermentação com n-hexano. O processo de imobilização da enzima foi realizado em cascata em 4 ciclos com a finalidade de sobrecarga da enzima no suporte. Os testes de estabilidade foram feitos por 24 horas, nas temperaturas de 30 à 70ºC e pH de 3 a 9 com a enzima livre e imobilizad... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Lipases are enzymes widely applied in industrial processes. They can be obtained by filamentous fungi which presents some advantages in relation to other sources and for this reason, studies aiming to increase its production have been performed. Moreover, the process of enzyme immobilization can improve the enzyme stability in relation to temperature and pH, and reduce the costs associated with its application due to the possibility of immobilized enzyme reuse in biocatalytic processes. The objective of this work was to study the production of lipases by Aspergillus sp. DPUA 1727, the immobilization of lipases produced in octyl-sepharose support and make the enzyme characterization in its free and immobilized form. Furthermore, the immobilized enzyme was applied to obtain the ester isoamyl propionate. Methods: the enzyme production was carried out for 96 hours in submerged culture, with different carbon sources (soybean, olive, grape seed, and cotton oils) as substrates. Subsequently, the enzyme immobilization in octyl-sepharose® support by adsorption through hydrophobic interaction was studied ( to this experiment the fermented medium was submitted to 4 cycles to extract the residual oil with n-hexane). The enzyme immobilization process was carried out in cascade employing 4 cycles with the purpose of overloading the enzyme in the support. Stability studies were done for 24 hours, at temperatures from 30 to 70ºC and pH from 3 to 9 with the enzyme-free and immobilized. As the last step of this work, the immobilized enzyme was applied in the preparation of the ester isoamyl propionate. Results: In the production stage, the best condition to obtain the enzyme... (Complete abstract click electronic access below) / Doutor
202

Radial-Basis-Function Neural Network Optimization of Microwave Systems

Murphy, Ethan Kane 13 January 2003 (has links)
An original approach in microwave optimization, namely, a neural network procedure combined with the full-wave 3D electromagnetic simulator QuickWave-3D implemented a conformal FDTD method, is presented. The radial-basis-function network is trained by simulated frequency characteristics of S-parameters and geometric data of the corresponding system. High accuracy and computational efficiency of the procedure is illustrated for a waveguide bend, waveguide T-junction with a post, and a slotted waveguide as a radiating element.
203

The use of a Coulter counter to quantitatively determine mold in cabonated soft drinks ; The investigation of dimeric halogen addition to piaselenole ; Ultrasonic attenuation of metal chelates / Use of a Coulter counter to quantitatively determine mold in carbonated soft drinks

Blaha, John Joseph January 2011 (has links)
Digitized by Kansas Correctional Industries
204

Avaliação do lodo de curtume como fonte de nutrientes para o crescimento inicial de eucalipto /

Gamba, Vítor Surian, 1986- January 2012 (has links)
Orientador: Alcides Lopes Leão / Banca: Iraê Amaral Guerrini / Banca: Fernando Carvalho Oliveira / Resumo: As áreas plantadas com florestas de espécies do gênero Eucalyptus estão em franca ascendência no Brasil, o que resulta na necessidade de grande quantidade de insumos para manter os elevados índices produtivos. Devido à elevação dos preços de alguns produtos agrícolas, a utilização de recursos alternativos para fornecer aporte à produção florestal no país é de grande interesse do setor. Como exemplos citam-se os Estados Unidos, Holanda e outros países que utilizam resíduos orgânicos industriais e urbanos para o fornecimento de nutrientes à agricultura e silvicultura. Uma alternativa em potencial para o Brasil são os resíduos gerados por indústrias de curtimento de peles, visto que o país é um dos maiores produtores de couros do mundo e gera grandes quantidades de resíduos. Com isso, é dado um destino economicamente e ambientalmente mais correto aos resíduos, além de gerar economia de insumos no setor florestal. O objetivo deste trabalho é avaliar o desenvolvimento de um híbrido de Eucalyptus urophylla com Eucalyptus grandis submetidos às diferentes doses de lodo compostado e lodo de caleiro, ambos provenientes da indústria de curtimento de couro. Para isso foi realizado um experimento em vasos dentro de uma estufa plástica no Departamento de Recursos Naturais - Ciências Ambientais da Faculdade de Ciências Agronômicas de Botucatu, e foram avaliados o diâmetro e altura das plantas, massa seca de raiz, caule e folhas, teor de clorofila, além do teor de nutrientes no solo e nas folhas. A utilização de doses crescentes de ambos os resíduos resultou na melhoria dos parâmetros biométricos das características físico químicas do solo, no fornecimento de nutrientes ao solo e maior acúmulo de nutrientes nas folhas. As doses de 20 e 30 Mg ha-1 do resíduo de caleiro foram as que proporcionaram melhores condições às plantas e ao solo / Abstract: The area of Eucalyptus forest used for commercial purposes is rising in Brazil, resultings in the use of large amounts of inputs to mainten higher productivity. Due to rising fertilizer prices, the use of alternatives resources is important to provide options for forest farmers and to reduce costs. The United States, Netherlands and other countries have used industrial and urban wastes in agriculture and forestry as a supply of nutrients. In Brazil, the wastes of tannery industry are a potential alternative. The country is one of the biggest tanner producers in the world, and this sector generates large quantites of waste. Forest fertilization is both an economically and environmentally superior use of this waste, and it lowers the costs of forest production. Therefore, the objective of this work is to evaluate the development of a Eucalyptus hybrid (E. Grandis x E. Urophylla) with the use of tannery wastes to provide nutrients. The experiment was carried out in vases inside the greenhouse of the Department of Natural Resources - Environmental Sciences in the College of Agricultural Sciences, Botucatu, Brazil. The parameters checked ware height and diameter of plants; dry mass of roots, stem and leafs; and chlorophyll content and nutrient content of the soil and leaves. The use of increasing doses of both residues resulted in the rise of biometric parameters, improved soil physicochemical characteristics, the supply of nutrients to soil and nutrient content in leaves. Thetreatments of 20 and 30 Mg ha-1 of liming residue resulted in the best conditions for plants growth and soil fertility / Mestre
205

Ultra-High Capacity Silicon Photonic Interconnects through Spatial Multiplexing

Chen, Christine P. January 2017 (has links)
The market for higher data rate communication is driving the semiconductor industry to develop new techniques of writing at smaller scales, while continuing to scale bandwidth at low power consumption. The question arises of how to continue to sustain this trend. Silicon photonic (SiPh) devices offer a potential solution to the electronic interconnect bandwidth bottleneck. SiPh leverages the technology commensurate of decades of fabrication development with the unique functionality of next-generation optical interconnects. Finer fabrication techniques have allowed for manufacturing physical characteristics of waveguide structures that can support multiple modes in a single waveguide. By refining modal characteristics in photonic waveguide structures, through mode multiplexing with the asymmetric y-junction and microring resonator, higher aggregate data bandwidth is demonstrated via various combinations of spatial multiplexing, broadening applications supported by the integrated platform. The main contributions of this dissertation are summarized as follows. Experimental demonstrations of new forms of spatial multiplexing combined together exhibit feasibility of data transmission through mode-division multiplexing (MDM), mode-division and wavelength-division multiplexing (MDM-WDM), and mode-division and polarization-division multiplexing (MDM-PDM) through a C-band, Si photonic platform. Error-free operation through mode multiplexers and demultiplexers show how data can be viably scaled on multiple modes and with existing spatial domains simultaneously. This work opens up new avenues for scaling bandwidth capacity through leveraging orthogonal domains available on-chip, beyond what had previously been employed like WDM and time-division multiplexing (TDM). Furthermore, we explore expanding device channel support from two to three arms. Finding that a slight mismatch in the third arm can increase crosstalk contributions considerably, especially when increasing data rate, we explore a methodical way to design the asymmetric y-junction device by considering its angles and multiplexer/demultiplexer arm width. By taking into consideration device fabrication variations, we turn towards optimizing device performance post-fabrication. Through ModePROP simulations, optimizing device performance dynamically post-fabrication is analyzed, through either electro-optical or thermo-optical means. By biasing the arm introducing the slight spectral offset, we can quantifiably improve device performance. Scaling bandwidth is experimentally demonstrated through the device at 3 modes, 2 wavelengths, and 40 Gb/s data rate for 240 Gb/s aggregate bandwidth, with the potential to reduce power penalty per the device optimization process we described. A main motivation for this on-chip spatial multiplexing is the need to reduce costs. As the laser source serves as the greatest power consumer in an optical system, mode-division multiplexing and other forms of spatial multiplexing can be implemented to push its potentially prohibitive cost metrics down. While the device introduces loss, through imperfect mode isolation, as device fabrication improves, tolerance can increase as well. Meanwhile, the rate that laser power consumption increases as supported wavelengths scales is shown to be much faster than the loss introduced by scaling on-chip bandwidth multi-modally. Future generations of ultra-high capacity devices through spatial multiplexing is explored. Already various systems can be implemented multimodally, with the design features serving as useful for other components. Central to photonic network-on-chips, a multimodal switch fabric, composed of microring resonators, is demonstrated to have error-free operation of 1x2 switching of 10 Gb/s data. These contributions aim to scale bandwidth to ultra-high capacity, while ameliorating any imperfect design, through multiple routes conjoined with on-chip spatial multiplexing, and they constitute the bulk of this dissertation. For the latter part, we turn to the issue of integrating a photonic device for dynamic power reallocation in a system. Specifically, we utilize a 4x4 nonblocking switch fabric composed of Mach-Zehnder interferometers that switch both electro-optically and thermo-optically at ns and μs rates respectively. In order to demonstrate an intelligent platform capable of dynamically multicasting data and reallocating power as needed by the system, we must first initialize the switch fabric to control with an electronic interface. A dithering mechanism, whereby exact cross, bar, and sub-percentage states are enforced through the device, is described here. Such a method could be employed for actuating the device table of bias values to states automatically. We then employ a dynamic power reallocation algorithm through a data acquisition unit, showing real-time channel recovery for channels experiencing power loss by diverting power from paths that could tolerate it. The data that is being multicast through the system is experimentally shown to be error-free at 40 Gb/s data rate, when transmitting from one to three clients and going from automatic bar/cross states to equalized power distribution. For the last portion of this topic, the switch fabric was inserted into a high-performance computing system. In order to run benchmarks at 10 Gb/s data ontop of the switch fabric, a newer model of the control plane was implemented to toggle states according to the command issued by the server. Such a programmable mechanism will prove necessary in future implementations of optical subsystems embedded inside larger systems, like data centers. Beyond the specific control plane demonstrated, the idea of an intelligent photonic layer can be applied to alleviate many kinds of optical channel abnormalities or accommodate for switching based on different patterns in data transmission. Besides spatial-multiplexing, expanding on-chip bandwidth can be accomplished by extension of the wavelength detection regime to a longer regime. Experimental demonstration of photodetection at 1.9 μm is shown with Si+-doped Si photodetectors at 1 Gb/s data operation featuring responsivities of .03 AW−1 at 5 V bias. The same way of processing these Si ribbed waveguide photodetectors can garner even longer wavelength operation at 2.2 μm wavelength. Finally, the experimental demonstration of a coherent perfect absorption Si modulator is exhibited, showing a viable extinction ratio of 24.5 dB. Using this coherent perfect absorption mechanism to demodulate signals, there is the added benefit of differential reception. Currently, an automated process for data collection is employed at a faster time scale than instabilities present in fibers in the setup with future implementations eliminating the off-chip phase modulator for greater signal stability. The field of SiPh has developed to a stage where specific application domains can take off and compete according to industrial-level standards. The work in this dissertation contributes to experimental demonstration of a newly developing area of mode-division multiplexing for substantially increasing bandwidth on-chip. While implementing the discussed photonic devices in dynamic systems, various attributes of integrated photonics are leveraged with existing electronic technologies. Future generations of computing systems should then be designed by implementing both system and device level considerations.
206

Contribution to the study of projection-based systems for industrial applications in mixed reality / Contribution à l’étude des systèmes de projection pour des applications industrielles en réalité mixte

Cortes, Guillaume 24 October 2018 (has links)
La réalité mixte apporte certains avantages aux applications industrielles. Elle peut, entre autres, faciliter la visualisation et validation de projets ou assister des opérateurs durant des tâches spécifiques. Les systèmes de projection (PBS), tels que les CAVE ou la réalité augmentée spatiale, fournissent un environnement de réalité mixte permettant une collaboration directe avec des utilisateurs externes. Dans cette thèse, nous visons à améliorer l'utilisation des systèmes de projection pour des applications industrielles en abordant deux défis majeurs: (1) améliorer les composantes techniques des PBS et (2) augmenter l'expérience utilisateur dans les PBS. En tant que premier défi technique, nous visons à améliorer les systèmes de suivi de mouvements optiques. Nous proposons une approche permettant d’élargir l’espace de travail de ces systèmes grâce à deux méthodes. La première permet de suivre les mouvements à partir d’une seule caméra tandis ce que la deuxième permet de contrôler les caméras et suivre les objets dans l’espace de travail. Le système qui en résulte fournit des performances acceptables pour des applications en réalité mixte tout en augmentant considérablement l'espace de travail. Un tel système de suivi de mouvement peut permettre de mieux exploiter le potentiel des systèmes de projection et d’élargir le champ possible des interactions. En tant que deuxième défi technique, nous concevons un casque « tout-en-un » pour la réalité augmentée spatiale mobile. Le casque rassemble à la fois un système de projection et un système de suivi de mouvements qui sont embarqués sur la tête de l'utilisateur. Avec un tel système, les utilisateurs sont capables de se déplacer autour d'objets tangibles et de les manipuler directement à la main tout en projetant du contenu virtuel par-dessus. Nous illustrons notre système avec deux cas d'utilisation industriels: le prototypage virtuel et la visualisation médicale. Enfin, nous abordons le défi qui vise à améliorer l’expérience utilisateur dans les PBS. Nous proposons une approche permettant d’incarner un personnage virtuel et d’augmenter la perception spatiale des utilisateurs dans les PBS. Pour ce faire, nous ajoutons l’ombre virtuelle des utilisateurs dans les systèmes de projection immersifs. L'ombre virtuelle est directement corrélée aux mouvements des utilisateurs afin qu'ils la perçoivent comme si c'était la leur. Nous avons effectué une expérience afin d'étudier l'influence de la présence de l'ombre virtuelle sur le comportement des utilisateurs. / Mixed reality brings some advantages to industrial applications. It can, among others, facilitate visualizing and validating projects or assist operators during specific tasks. Projection-based Systems (PBS), such as CAVEs or spatial augmented reality provide a mixed reality environment enabling straightforward collaboration with external users. In this thesis, we aim at improving the usage of PBS for industrial applications by considering two main challenges: (1) improving the technical components of PBS and (2) improving the user experience when using PBS. As a first technical challenge, we propose to address the improvement of the tracking component. We introduce an approach that enables increasing the workspace of optical tracking systems by using two methods. As a first method, we propose to use monocular tracking. As a second method, we propose to use controlled cameras that follow the targets across the workspace. The resulting system provides acceptable performances for mixed reality applications while considerably increasing the workspace. Such a tracking system can make it easier to use large projection-based displays and can widen the range of available interactions. As a second technical challenge, we design an “all-in-one” headset for mobile spatial augmented reality on tangible objects. The headset gathers both a projection and a tracking system that are embedded on the user’s head. With such a system, the users are able to move around tangible objects and to manipulate them directly by hand while projecting virtual content over them. We illustrate our system with two industrial use cases: virtual prototyping and medical visualization. Finally, we address the challenge that aims at improving the user experience when using PBS. We introduce a method that provides virtual embodiment and increases the spatial perception of the users when using PBS. To do so we add the user’s virtual shadow in immersive projection-based systems. The virtual shadow is dynamically mapped to users’ movements in order to make them perceive the shadow as if it was their own. We then carry out an experiment to study the influence of the presence of the virtual shadow on the user experience and behavior.
207

Characterization of Ti-6Al-4V Produced Via Electron Beam Additive Manufacturing

Hayes, Brian J. 12 1900 (has links)
In recent years, additive manufacturing (AM) has become an increasingly promising method used for the production of structural metallic components. There are a number of reasons why AM methods are attractive, including the ability to produce complex geometries into a near-net shape and the rapid transition from design to production. Ti-6Al-4V is a titanium alloy frequently used in the aerospace industry which is receiving considerable attention as a good candidate for processing via electron beam additive manufacturing (EBAM). The Sciaky EBAM method combines a high-powered electron beam, weld-wire feedstock, and a large build chamber, enabling the production of large structural components. In order to gain wide acceptance of EBAM of Ti-6Al-4V as a viable manufacturing method, it is important to understand broadly the microstructural features that are present in large-scale depositions, including specifically: the morphology, distribution and texture of the phases present. To achieve such an understanding, stereological methods were used to populate a database quantifying key microstructural features in Ti-6Al-4V including volume fraction of phases, a lath width, colony scale factor, and volume fraction of basket weave type microstructure. Microstructural features unique to AM, such as elongated grains and banded structures, were also characterized. Hardness and tensile testing were conducted and the results were related to the microstructural morphology and sample orientation. Lastly, fractured surfaces and defects were investigated. The results of these activities provide insight into the process-structure-properties relationships found in EBAM processed Ti-6Al-4V.
208

An Initial Study of Binary and Ternary Ti-based Alloys Manufactured Using Laser Engineered Net Shaping (LENSTM)

Gray, Alyn M. 12 1900 (has links)
In this study an initial assessment of the composition – microstructure – property relationships in binary and ternary Ti – based systems are made possible using LENSTM technology. Laser Engineering Net Shaping (LENSTM), a rapid prototyping, directed laser deposition methodology of additive manufacturing (AM) was used to create bulk homogenous specimens that are compositionally graded. Compositionally graded specimens were made possible by incorporating elemental blends of powder during the LENSTM process. While there have been numerous studies assessing the influence of common elements (e.g., V, Mo, Al, and Cr) on the resulting microstructure in titanium alloys, other elements have been neglected. A systematic study of the Ti – Fe – Al ternary system based upon varying compositions of the eutectoid former, Fe with Al to stabilize the a and b phases respectively has also been neglected. This research effort focuses on exploiting the LENSTM process by rapidly assessing the composition – microstructure – property relationships in a combinatorial approach for the Ti – W, Ti – Fe, and Ti – Fe – Al systems. Compositionally graded specimens of Ti – xW (0<x<40wt.%(14.79at.%)), Ti – xFe (0<x<35wt.%(36.37at.%)), and Ti – xFe – yAl (0<x<40wt.%(36.37at.%)), y=5,10, 15wt.%) have been heat treated to also assess the influence of thermal history on microstructural features such as phase composition and volume fraction. Lastly, a Ti – xMo (0<x<40wt.%(24.96at.%)) compositionally graded specimen was deposited to re-assess the Mo-equivalency nature of W, as well as assess the role of phase separation in microstructural evolution at temperatures above and below the invariant point (~695°C) of the Ti – W binary system.
209

Fermentation study of glucose isomerase. / CUHK electronic theses & dissertations collection

January 2005 (has links)
Glucose isomerase (GI) catalyzes the conversion of D-glucose to D-fructose in vitro. It is one of the bulkiest commercial enzymes, essential for the mass production of high-fructose corn syrup (HFCS) and crystalline fructose. / In this study, the effects of nitrogen sources, carbon sources, expression vectors, host strains, bacterial (Vitreoscilla) hemoglobin, selective pressure, plasmid stability and fermentation process on the GI production were investigated. The results showed that E. coli could express cloned thermostable GI at high expression level. E. coli transformed with the recombinant plasmid P-lac-GI gave the best result in term of total GI production and expression level. Corn steep liquor could be used as a cheap alternative nitrogen source for what was in LB medium. The concentration of glucose affected the expression level of GI significantly. Replacement of the ampicillin resistance gene by kanamycin resistance gene improved the plasmid stability leading to high productivity of GI in fed-batch fermentation. A suicide system could further improve the plasmid stability resulting in a high productivity of GI. A feeding strategy for fed-batch fermentation with the optimized parameters was developed to result in the production of up to 3g/L recombinant GI, which constituted 50% of the total soluble proteins. The total yield was 5-fold higher than that from flask experiments and 7-fold higher than the highest ever recorded. The expression level was also 100% higher than it was in other reports. / Liu Zhaoming. / "August 2005." / Advisers: J. Wang; W. P. Fong. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3780. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 129-154). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
210

Immobilization study of glucose isomerase. / CUHK electronic theses & dissertations collection

January 2005 (has links)
Glucose isomerase (GI) catalyzes the isomerization of glucose to fructose and consequently is one of the bulkiest industrial enzyme for the manufacture of high fructose corn syrup and crystalline fructose. The GI is used in industry mainly in the form of immobilized enzyme. / In this work, the immobilization of GI had been studied by several methods: ion exchange adsorption, covalent binding, alginate cells entrapment and cells cross-linking. Three kinds of carrier support (ion exchange resin, epoxy resin and amino resin) have been used in the immobilization of cells-free enzyme; the whole cells immobilization of GI by cross-linking agents polyethyleneimid and glutaraldehyde were critically examined. The results show that the cells cross-linking is the best method to prepare the immobilized GI products, as it is high in specific activity and thermostability, and low the cost. The method is likely to make significant contribution to the field of immobilization, its application has expanding rapidly in many walks of the society, including environment protection, food and pharmaceutical industries. / Jin, Caike. / "August 2005." / Adviser: Jun Wang. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3521. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 125-152). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

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