京都大学 / 新制・課程博士 / 博士(理学) / 甲第25085号 / 理博第4992号 / 京都大学大学院理学研究科数学・数理解析専攻 / (主査)教授 加藤 毅, 教授 入谷 寛, 教授 塚本 真輝 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Submitted in fulfillment of the requirements for the degree of Master of Engineering in Chemical Engineering, Durban University of Technology. Durban. South Africa, 2015. / Several areas in the world such as the United States of America, Sri Lanka, China, Argentina, Canada, Tanzania, Kenya, South Africa and many others have a problem of high fluoride content in drinking water. Generally fluoride levels above 1.5 ppm in water may result in dental and skeletal fluorosis in humans depending on quantity consumed (Fan et al., 2003; Meenakshi, 2004). Remote rural areas where there are no water treatment facilities are more vulnerable to this problem. Adsorbents such as activated alumina and FR-10 resin seem to have a potential for successful application in rural areas. These methods however require pre-treatment if the feed has high turbidity. A membrane based system called woven fabric microfiltration gravity filter (WFMFGF) developed by Durban University of Technology proved to be suitable for turbidity removal. The main objective of this research was to develop a small water treatment system for fluoride removal. The small water treatment system developed in this study consists of WFMFGF for pre-treatment and an adsorption column. The WFMFGF is made up of a 40 L container packed with 15 immersed flat sheet membrane elements. The operation of the WFMFGF is in batch mode, driven by varying static head. The static head variation results in flow rate variation through the system. This in turn result in variation of contact time, velocity as well as pressure drop in the fluoride removal unit. Specific objectives of the study were: (1) to establish the maximum and minimum flow rates through the WFMFGF system, the total run time before cleaning is required and the best cleaning method for this particular membrane system. (2) to evaluate and compare the performance of activated alumina and FR-10 resin on varying contact time, velocity and pressure drop on the fluoride removal unit. The adsorbents were also compared on adsorption capacity, cost and ease of operation. The minimum and maximum flow rates through the WFMFGF were found to be 5 l/hr and 100 l/hr respectively. It was found that the system can be run for more than a month before requiring cleaning. The suitable cleaning method was found to be soaking the membranes in 0.0225 percent sodium hypochlorite solution overnight and brushing them using a plastic brush. The comparison of the performance of FR-10 resin to activated alumina found that the adsorbents gave equal performance based on the given criteria. FR-10 resin had higher adsorption capacity, gave good quality treated water even with shorter contact time and operated at wider velocity range. Activated alumina on the other hand had an advantage of lower costs, lower pressure drop and ease of use. According to Pontius (1990), the performance of activated alumina can be improved by intermittent operation. Point of use (POU) systems are generally operated intermittently. This improves the fluoride removal efficiency of activated alumina giving it more advantage over FR-10 resin. Based on this activated alumina was selected as the best adsorbent for the system. After the adsorbent was selected, the adsorption column was designed. The column operation regime was 3.5 minutes minimum contact time and 1.17 to 7.8 m/hr velocity range. The activated alumina adsorption capacity was 1.53mg/g. The column had an inside diameter of 70 mm. It was packed with activated alumina to a bed height of 400 mm. The column inlet and outlet pipes were made of PVC with a standard pipe size of 20 mm outside diameter. A valve at the column inlet pipe allowed water to flow through the system.

<p>Problem – The expansion of global trade and supply chain integration has put great emphasison logistics, particularly in the intermediary sector, freight forwarders. Whilst in developedcountries freight forwarders benefit from competitive markets and trade facilitatingpolicies, this sector in West coast Africa exhibits low logistics performance levels. Inorder to address such issues, one needs to analyse the problem and identify the causes; thisthesis focuses on identifying the bottlenecks in the freight-forwarding sector in west coastAfrica.Purpose – The main purpose of this study is to identify the bottleneck/s within thefreight-forwarding industry in west coast Africa, namely: Angola, Cameroon, DR of Congo,Gabon, and Nigeria.Method – This thesis employs a pre-study and case study method, to ensure sufficient collectionof relevant material, taking into account the lack of research in this subject. We usedthe material obtained from the interviews and the secondary source, to structure our purpose,research questions, and to define the case of our study.Results – The study concludes with a series of interesting findings; First, the activity of aFreight Forwarder depends on a series of factors that do not depend on the Freight Forwarderper se. And second, Freight Forwarders in order to accomplish their tasks, have accessto services that are shared by all providers, and that are beyond their control. To conclude,the study identifies infrastructure as a major bottleneck in the Freight Forwarding sector.</p>

Cette thèse porte sur l'analyse mathématique de modèles de réaction-dispersion de la forme [delta]tu=D(u) +f(x,u). L'objectif est de comprendre l'influence du terme de réaction f, de l'opérateur de dispersion D, et de la donnée initiale u0 sur la propagation des solutions de ces équations. Nous nous sommes intéressés principalement à deux types d'équations de réaction-dispersion : les équations de réaction-diffusion où l'opérateur de dispersion différentielle est D=[delta]2z et les équations intégro-différentielles pour lesquelles D est un opérateur de convolution, D(u)=J* u-u. Dans le cadre des équations de réaction-diffusion en milieu homogène, nous proposons une nouvelle approche plus intuitive concernant les notions de fronts progressifs tirés et poussés. Cette nouvelle caractérisation nous a permis de mieux comprendre d'une part les mécanismes de propagation des fronts et d'autre part l'influence de l'effet Allee, correspondant à une diminution de la fertilité à faible densité, lors d'une colonisation. Ces résultats ont des conséquences importantes en génétique des populations. Dans le cadre des équations de réaction-diffusion en milieu hétérogène, nous avons montré sur un exemple précis comment la fragmentation du milieu modifie la vitesse de propagation des solutions. Enfin, dans le cadre des équations intégro-différentielles, nous avons montré que la nature sur- ou sous-exponentielle du noyau de dispersion J modifie totalement la vitesse de propagation. / This thesis deals with the mathematical analysis of reaction-dispersion models of the form [delta]tu=D(u) +f(x,u). We investigate the influence of the reaction term f, the dispersal operator D and the initial datum u0 on the propagation of the solutions of these reaction-dispersion equations. We mainly focus on two types of equations: reaction-diffusion equations (D=[delta]2z and integro-differential equations (D is a convolution operator, D(u)=J* u-u). We first investigate the homogeneous reaction-diffusion equations. We provide a new and intuitive explanation of the notions of pushed and pulled traveling waves. This approach allows us to understand the inside dynamics the traveling fronts and the impact of the Allee effect, that is a low fertility at low density, during a colonisation. Our results also have important consequences in population genetics. In the more general and realistic framework of heterogeneous reaction-diffusion equations, we exhibit examples where the fragmentation of the media modifies the spreading speed of the solution. Finally, we investigate integro-differential equations and prove that emph{fat-tailed} dispersal kernels J, that is kernels which decay slower than any exponentially decaying function at infinity, lead to acceleration of the level sets of the solution u.

[pt] A tese Viagens modernistas: Europa e Brasil sob a ótica de António de Alcântara Machado, Blaise Cendrars e Oswald de Andrade parte da leitura comparada de três obras literárias publicadas durante a década de 1920, Pathé-Baby (1926), de António de Alcântara Machado; Pau Brasil (1925), de Oswald de Andrade; e Feuilles de route (primeiramente dividida em três partes editadas entre 1924 e 1928, Le Formose, São Paulo e Inédites, e reunidas pelo autor em 1944), de Blaise Cendrars (escritor suíço de expressão francófona). Tendo por premissa três eixos temáticos que aproximam tais obras – a saber, as vanguardas históricas, a viagem e o olhar do autor-viajante –, a tese aponta como a literatura de viagem e o olhar sobre o outro se modificaram com o advento das vanguardas e se estrutura, assim, a partir de três questões principais suscitadas pela leitura do corpus literário. Primeiramente, investiga em que medida os referidos textos contribuem para a solidificação do projeto modernista brasileiro, ao trazer para a cena de vanguarda, eminentemente urbana, a poesia e a crônica de viagem. Em seguida, elucida as maneiras pelas quais se trava o diálogo entre a modernidade europeia presenciada por Alcântara Machado – e trazida a nós também por Blaise Cendrars – e o passado colonial brasileiro que Oswald desvela em seu ritual antropofágico de construção da vanguarda artística brasileira. Por fim, analisa em que medida se pode considerar Pau Brasil e Feuilles de route obras espelhadas, simétricas, em que a paisagem e a história do Brasil guiam o olhar e a pena de ambos os poetas, permitindo lê-las como obras contínuas, como uma espécie de guia poético de uma viagem que, zarpando da Europa, adentra o Brasil e a ela retorna. Além disso, uma vez que tal leitura é feita à luz tanto de teorias sobre literatura de viagem como dos estudos culturais, também se discutem outros aspectos como discursos de identidade e alteridade, cosmopolitismo, experiência urbana, e intermidialidade. / [en] Modernist Journeys: Europe and Brazil from the Perspective of António de Alcântara Machado, Blaise Cendrars and Oswald de Andrade is a thesis that starts from the comparative reading of three literary works published during the 1920s, Pathé-Baby (1926) by António de Alcântara Machado; Pau Brasil (1925), by Oswald de Andrade; and Feuilles de route (first divided in three parts, edited between 1924 and 1928, Le Formose,São Paulo and Inédites, and later collected by the author in 1944), by Blaise Cendrars (Swiss writer of French-speaking expression). Having as its premise three thematic axes that approximate such works – namely, the historical vanguards, the journey and the traveling author s point of view –, the thesis points out how the travel literature and the look on the other have changed with the advent of the vanguards and is thus structured on the basis of three main questions raised by the reading of the literary corpus. Firstly, it investigates to what extent these texts contribute to the solidification of the Brazilian modernist project, by bringing poetry and travel chronicles to the vanguard scene, eminently urban. It then elucidates the ways in which the dialogue between the European modernity witnessed by Alcântara Machado – and brought to us by Blaise Cendrars – and the Brazilian colonial past that Oswald reveals in his anthropophagic ritual of building the Brazilian artistic vanguard, is elucidated. Finally, it analyzes the extent to which one can consider Pau Brasil and Feuilles de route mirrored, symmetrical works, in which the landscape and the history of Brazil guide the eyes and the pen of both poets, allowing them to read them as continuous works, as a kind of poetic guide of a journey that, starting from Europe, enters Brazil and returns to it. Moreover, since such a reading is made in light of both theories on travel literature and cultural studies, other aspects such as discourses of identity and otherness, cosmopolitanism, urban experience, and intermediality are also discussed. / [fr] La thèse Voyages modernistes : l Europe et le Brésil dans la perspective de António de Alcântara Machado, Blaise Cendrars et Oswald de Andrade part de la lecture comparative de trois oeuvres littéraires publiées au cours des années 1920, Pathé-Baby (1926), de António de Alcântara Machado ; Pau Brasil (1925), de Oswald de Andrade ; et de Feuilles de route (au début divisée en trois parties éditées entre 1924 et 1928, Le Formose, São Paulo et Inédites, et réunies par l auteur en 1944), de Blaise Cendrars. À partir de trois thèmes principaux qui amènent ces oeuvres – à savoir, les avant-gardes historiques, le voyage et le regard de l auteur-voyageur –, la thèse démontre comment la littérature de voyage et le regard de l autre ont changé avec l arrivée des avant-gardes et se construit, ainsi, à partir de trois questions principales soulevées par la lecture du corpus littéraire. Tout d abord, cette thèse examine dans quelle mesure ces textes contribuent à la solidification du projet moderniste brésilien, en portant la poésie et la chronique de voyage à la scène de l avant-garde, éminemment urbaine. Ensuite, elle élucide les façons par lesquelles se donne le dialogue entre la modernité européenne témoignée par Machado – et aussi apportée à nous par Blaise Cendrars – et le passé colonial brésilien, lequel Oswald révèle dans son rituel cannibale de construction de l avant-garde artistique brésilienne. Enfin, elle analyse dans quelle mesure Pau Brasil et Feuilles de route peuvent être considérés des oeuvres en miroir, symétriques, où le paysage et l histoire du Brésil guident le regard et l écriture de ces poètes, ce qui permet de les lire comme des oeuvres continues, une sorte de guide poétique de voyage qui part de l Europe vers le Brésil et à elle retourne. En outre, une telle lecture étant faite à la lumière des deux théories sur la littérature de voyage et les études culturelles, d autres aspects tels que les discours d identité et d altérité, le cosmopolitisme, l expérience urbaine et l intermédialité sont également discutés.

Andelen vegetarianer och veganer i världen ökar successivt. En av många anledningar till detta är att man som mottagare påverkas av djurrättsliga publiceringar på sociala medier. Många organisationer som försöker stoppa djurplågeri och förespråka ett veganskt leverne väljer att, genom sin visuella kommunikation, inrama sina publiceringar negativt, vilket kan tas emot som stötande av mottagaren. Denna studies syfte är därför att undersöka hur mottagaren påverkas av stötande innehåll i form av fotografier på sociala medier, med en djurrättsorganisation som avsändare. Organisationen valdes ut i en initial förstudie, tillsammans med sex fotografier uppdelade i tre innehållstyper. Dessa olika innehållstyper låg till grund för en kvantitativ del i form av en enkät som besvarades av 49 informanter, för att få klarhet kring vilken som mottogs bäst - och varför. Därefter följde en kvalitativ del, där en fokusgrupp bestående av sex informanter fick tycka till och diskutera de tre kategorierna av bilder. Studiens resultat visar att de tre innehållstyperna är olika effektiva beroende på mottagaren. Mottagare som ofta utsätter sig för stötande innehåll blir mättade och kan lätt bli emotionellt distanserade. Likaså visar studien att en alltför enformig inramning från organisationens sida kan resultera i att innehållet blir synonymt med dem och att mottagaren kopplar de negativa känslor som väcks av bilderna direkt till organisationen.

<p>Sectra Communications AB has developed a terminal for encrypted communication called the Tiger platform. During voice communication delays have sometimes been experienced resulting in conversational complications.</p><p>A solution to this problem, as was proposed by Sectra, would be to introduce voice activity detection, which means a separation of speech parts and non-speech parts of the input signal, to the Tiger platform. By only transferring the speech parts to the receiver, the bandwidth needed should be dramatically decreased. A lower bandwidth needed implies that the delays slowly should disappear. The problem is then to come up with a method that manages to distinguish the speech parts from the input signal. Fortunately a lot of theory on the subject has been done and numerous voice activity methods exist today.</p><p>In this thesis the theory of voice activity detection has been studied. A review of voice activity detectors that exist on the market today followed by an evaluation of some of these was performed in order to select a suitable candidate for the Tiger platform. This evaluation would later become the foundation for the selection of a voice activity detector for implementation.</p><p>Finally, the implementation of the chosen voice activity detector, including a comfort noise generator, was done on the platform. This implementation was based on the special requirements of the platform. Tests of the implementation in office environments show that possible delays are steadily being reduced during periods of speech inactivity, while the active speech quality is preserved.</p>

Nous pr��sentons une ��tude comparative de l'injection optique quasi-statique pour des lasers �� semi-conducteurs et des lasers �� fibre. La fabrication des lasers �� fibre �� contre-r��action r��partie est d��taill��e. L'��tude spectrale de l'injection de lasers �� semi-conducteurs pour des puissances inject��e usuelles (> -30 dBm) permet, par des cartographies, de caract��riser des r��gimes bistables, le r��gime de relaxation, et la synchronisation de chaos. Pour de faibles puissances inject��es (< -30 dBm), nous montrons que le laser esclave est un amplificateur de qualit�� pour de faibles signaux coh��rents, et observons l'attraction en fr��quance de l'esclave inject�� par le ma��tre. L'injection statique des lasers �� fibre permet d'observer une r��ponse dynamique dans le domaine temporel, li��e �� des ph��nom��nes de relaxation. Nous proposons des m��thodes de mesure, par injection optique, du facteur de Henry, de faibles largeurs spectrales, du taux d'��mission spontan��e du laser esclave.

Problem – The expansion of global trade and supply chain integration has put great emphasison logistics, particularly in the intermediary sector, freight forwarders. Whilst in developedcountries freight forwarders benefit from competitive markets and trade facilitatingpolicies, this sector in West coast Africa exhibits low logistics performance levels. Inorder to address such issues, one needs to analyse the problem and identify the causes; thisthesis focuses on identifying the bottlenecks in the freight-forwarding sector in west coastAfrica.Purpose – The main purpose of this study is to identify the bottleneck/s within thefreight-forwarding industry in west coast Africa, namely: Angola, Cameroon, DR of Congo,Gabon, and Nigeria.Method – This thesis employs a pre-study and case study method, to ensure sufficient collectionof relevant material, taking into account the lack of research in this subject. We usedthe material obtained from the interviews and the secondary source, to structure our purpose,research questions, and to define the case of our study.Results – The study concludes with a series of interesting findings; First, the activity of aFreight Forwarder depends on a series of factors that do not depend on the Freight Forwarderper se. And second, Freight Forwarders in order to accomplish their tasks, have accessto services that are shared by all providers, and that are beyond their control. To conclude,the study identifies infrastructure as a major bottleneck in the Freight Forwarding sector.

Sectra Communications AB has developed a terminal for encrypted communication called the Tiger platform. During voice communication delays have sometimes been experienced resulting in conversational complications. A solution to this problem, as was proposed by Sectra, would be to introduce voice activity detection, which means a separation of speech parts and non-speech parts of the input signal, to the Tiger platform. By only transferring the speech parts to the receiver, the bandwidth needed should be dramatically decreased. A lower bandwidth needed implies that the delays slowly should disappear. The problem is then to come up with a method that manages to distinguish the speech parts from the input signal. Fortunately a lot of theory on the subject has been done and numerous voice activity methods exist today. In this thesis the theory of voice activity detection has been studied. A review of voice activity detectors that exist on the market today followed by an evaluation of some of these was performed in order to select a suitable candidate for the Tiger platform. This evaluation would later become the foundation for the selection of a voice activity detector for implementation. Finally, the implementation of the chosen voice activity detector, including a comfort noise generator, was done on the platform. This implementation was based on the special requirements of the platform. Tests of the implementation in office environments show that possible delays are steadily being reduced during periods of speech inactivity, while the active speech quality is preserved.