This dissertation studies the effects of external integration and internal liberalization on the economic geography within a country when regions within the country have different access to the world market. The first paper introduces internal geography into the Melitz (2003) model to examine how external and internal liberalizations affect the economic geography within a country. By dividing a country into a coastal region and an inland region, the model shows that trade leads the coastal region have a higher than proportional share of industry, and causes firms in the coastal region to be larger and more productive than firms in the inland region. Both external and internal liberalizations encourage industry agglomeration in the coastal region. However, external trade liberalization leads to firm divergence, and internal liberalization leads to firm convergence, between coastal and inland regions. This allows me to test the relative importance of internal and external liberalization. Using Chinese data from 1998 to 2007, I find that the manufacturing sector grew faster in the coastal region than in the inland region after the WTO accession in 2001. Firms also converged between coastal and inland regions, indicating that internal liberalization had stronger effects during this period. In the second paper, I document large economic discontinuities across the east/non-east provincial borders in China and argue that the border effects are largely due to preferential policies that give the east advantages in international trade and economic development. Using counties contiguous to the borders of 4 plain provinces, I find that manufacturing activities (output, employment, and export) increase abruptly from the west to the east of the borders. The counties in the east also have a lower share of agricultural population and a higher share of output by foreign firms. The economic discontinuities are larger for non-state sectors than for the state sector and are stronger in non-mountain regions than in mountain regions. The large economic discontinuities are unlikely to be explained by geographic and cultural differences across the borders, and can be accounted for by the policy differences between east and non-east provinces. I find that the openness level and the index of market liberalization can account for a large part of the east/non-east divide. In the third paper, I use the ending of the Multi-fiber Arrangement (MFA) to study the effects of an external trade liberalization on Chinese textile and clothing industry. After the Multi-fiber Arrangement ended in 2005, Chinese textile and clothing exports in products that faced quotas before experienced significant boom. The effects are stronger in the coastal region than in the inland region. Using distance to the seaport as a measure of world-market access, I show that the external trade liberalization (the quota removal) had larger effects on regions with better access to the world market. A further analysis of firm entry shows that the large adjustment of export after the expiration of the MFA was largely due to destination and product expansions by existing firms.

This paper provides a non-technical overview of NEG models dealing with policy issues. Considered policy measures include alternative categories of public expenditure, international tax competition, unilateral actions of protection/liberalisation, and trade agreements. The implications of public intervention in two-region NEG models are discussed by unfolding the impact of policy measures on agglomeration/dispersion forces. Results are described in contrast with those obtained in standard non-NEG theoretical models. The high degree of abstraction limits the applicability of NEG models to real world policy issues. We discuss in some detail two extensions of NEG models to reduce this applicability gap: the cases of multi-regional frameworks and firm heterogeneity.

This article investigates the effects of introducing demography into the New Economic Geography. We generalize the constructed capital approach, which relies on infinite individual planning horizons, by introducing mortality. The resulting overlapping generation framework with heterogeneous individuals allows us to study the effects of aging on agglomeration processes by analytically identifying the level of trade costs that triggers catastrophic agglomeration. Interestingly, this threshold value is rather sensitive to changes in mortality. In particular, the introduction of a positive mortality rate makes the symmetric equilibrium more stable and therefore counteracts agglomeration tendencies. In sharp contrast to other New Economic Geography approaches, this implies that deeper integration is not necessarily associated with higher interregional inequality. / Series: Department of Economics Working Paper Series

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16887号 / 工博第3608号 / 新制||工||1545(附属図書館) / 29562 / 京都大学大学院工学研究科化学工学専攻 / (主査)教授 松坂 修二, 教授 宮原 稔, 教授 大嶋 正裕 / 学位規則第4条第1項該当

This paper provides a non-technical overview of NEG models dealing with policy issues. Considered policy measures include alternative categories of public expenditure, international tax competition, unilateral actions of protection/liberalisation, and trade agreements. The implications of public intervention in two-region NEG models are discussed by unfolding the impact of policy measures on agglomeration/dispersion forces. Results are described in contrast with those obtained in standard non-NEG theoretical models. The high degree of abstraction limits the applicability of NEG models to real world policy issues. We discuss in some detail two extensions of NEG models to reduce this applicability gap: the cases of multi-regional frameworks and firm heterogeneity.

Le carbonate de calcium précipité (CCP) est un additif multi-fonctionnel que l'on trouve dans de nombreuses applications telles que les peintures, la pharmacie, la cosmétique etc. Il peut être synthétisé industriellement par différents procédés mais la voie la plus commune est la carbonatation. Ce procédé consiste à faire barboter du dioxyde de carbone dans une suspension d'hydroxyde de calcium afin de produire des particules de CCP. Toutefois, la problématique inhérente à la synthèse et à l'utilisation de ce précipité est la maîtrise de l'agglomération des monoparticules. En effet, ces dernières sont de taille nanométrique et s'agglomèrent en structures "ouvertes" de taille micrométrique. Cette agglomération a des conséquences directes sur la conduite du procédé ainsi que sur les propriétés d'usage du produit final. Ainsi, le but de ce travail est d'appréhender les mécanismes de ce phénomène, de déterminer sa cinétique et d'étudier l'impact de différents paramètres opératoires dans des conditions industrielles complexes. Sous réserve que les cinétiques de nucléation et croissance cristalline soient connues, le noyau d'agglomération peut être obtenu grâce à un traitement mathématique des distributions de tailles expérimentales. En faisant varier différents paramètres du procédé, il apparait que la constante d'agglomération augmente avec la température alors qu'il existe un optimum par rapport au taux de cisaillement. En se basant sur cette conclusion, une expression de la constante d'agglomération est proposée en fonction du taux de cisaillement, qui pourra être utilisée pour contrôler l'agglomération dans le réacteur industriel / Precipitated calcium carbonate (PCC) is a mineral additive of various applications in paints, pharmacy, cosmetics, etc. It can be industrially synthesized through several ways but the most common one is the carbonation route. It consists in bubbling carbon dioxide in a suspension of calcium hydroxide to get particles of PCC. However, the challenge related to the synthesis and the use of this precipitate is the control of the agglomeration of the monoparticles. Indeed, they are agglomerated in micrometric "loose" structures. This agglomeration has consequences on the run of the process and the end use properties of the final product. Thus, the aim of this work is to understand the mechanisms of this phenomenon, to determine its kinetics and to study the impact of different process parameters under complex industrial conditions. The method to determine the agglomeration kernel is based on the resolution of a population balance using the moment approach. Provided that the kinetic rates of nucleation and growth are known, the agglomeration kernel can be obtained from a mathematical treatment of the experimental particle size distributions. Thanks to an agglomeration kernel model including the crystal growth, it is possible to determine the value of the agglomeration constant. Finally, by varying different process parameters, it also appears that the agglomeration constant increases with temperature whereas an optimum is observed for the shear rate. Regarding to this fact, we can also propose an expression of the agglomeration constant as a function of the shear rate, which can be used to control the agglomeration in the industrial reactor

Iron is often present in leach liquors produced in chemical and hydrometallurgical processes. It is known that voluminous iron precipitates with high impurity values are formed if the conditions during its formation are not controlled well. These products are also often difficult to treat in downstream processes. This study therefore focused on the determination of product quality parameters for the production of good quality iron precipitates from zinc-rich solutions. Special attention was given to the quality of metastable phases such as ferrihydrite and schwertmannite formed at elevated temperatures and in the pH range 1.5 to 3.5 in a continuous crystallizer. These phases are produced over a range of supersaturation levels with the best quality products formed at lower supersaturation. It was shown that most industrial processes are operated well above the metastability limit at relatively high supersaturation. However, stagewise precipitation of iron, even above the metastability limit, yielded better quality products. It was also shown that localized supersaturation levels could be controlled through changes in the micro and macromixing environments. The three-zone model approach was used to improve the quality of ferrihydrite and schwertmannite precipitates. Changes in the reactor design and the position of reagent feed points also impacted on the quality of the precipitates. Control over the localized supersaturation not only ensures the production of good quality nuclei, but also impacts on particle growth, which is required to make downstream processing of precipitates possible. In precipitation processes, growth mainly takes place through agglomeration as the rate of molecular growth is generally low. The final quality of iron precipitates is greatly influenced by the quality of the agglomerates formed during iron precipitation. A Hadamard matrix was used to indicate the relative importance of the most relevant operating parameters for the formation of good quality iron precipitates. / Thesis (PhD (Metallugical Engineering))--University of Pretoria, 2007. / Materials Science and Metallurgical Engineering / unrestricted

La localisation des industries a connu une forte évolution et un important développement dans l’agglomération du Grand Tunis, voire de fortes implications et rapports avec l’espace urbain de cette agglomération. En effet, les activités industrielles, en croissance depuis plus d’une trentaine d’année, ont fait apparaître de nouveaux besoins et de nouvelles nécessités d’organisation spatiale et d’aménagement de structures pour leur accueil. Or, les travaux de recherche et études consacrés aux relations et rapports entre la localisation des industries et les enjeux urbains de l’agglomération du Grand Tunis demeurent assez rares. C’est pour cette raison que nous avons choisi de concentrer notre effort de réflexion sur une analyse du binôme industrialisation-urbanisation, deux phénomènes concomitants marqués tantôt par des solidarités, tantôt par des ruptures. Plus précisément, notre travail entend contribuer à l’identification et la compréhension de la localisation des activités industrielles et à établir ses principales caractéristiques en rapport avec le développement de l’espace urbain de l’agglomération du Grand Tunis et l’évolution récente de l’industrie. Ce ne sont pas les activités industrielles en elles-mêmes, prises de façon abstraite, qui vont nous intéresser au premier chef, mais c’est avant tout leur matérialisation à travers les zones industrielles où elles semblent plus présentes. Il va s’agir pour nous de contribuer à une analyse plus spatiale de la question croisée de l’industrie et de l’urbain et plus particulièrement le lien entre la localisation industrielle et les enjeux du développement urbain. / The industrial localization has witnessed a significant evolution and an important development in the Great Tunis agglomeration, even huge implications and connections with its urban space. In fact, industrial activities which have beenincreasing more than thirty years ago, have brought up new needs and necessities for spatial organization and management structures for their implementation. Nevertheless, the studies and research works on the relationship between localization of industries and urban challenges remain rare. For this reason, we have chosen to concentrate our effort on the analysis of the binomial industrialization-urbanization, two concomitant phenomena marked sometimes by solidarity, sometimes by rupture. More precisely, we intend to contribute through this research, to the identification andthe understanding of industrial activities’ localization and to establish the principal characteristics in connection with the urban development of Great Tunis agglomeration and the recent industrial trend. They are not the industrial activitiesthemselves, considered in an abstract way, that firstly interest us, but their materialization via the industrial zones where they seem to be more present. We will contribute to a spatial analysis of the cross issue gathering industry and urbanizationand particularly the link between industrial localization and the urban development at stake.

Ce travail est une étude préliminaire qui a pour objectif principal d'étudier l'impact des caractéristiques de surface des poudres céréalières sur leurs mécanismes d'agglomération dans le cas particulier de la fabrication de couscous. Cet objectif a été réalisé par une approche multi-échelle : particules, mécanismes, et procèdes. A l'échelle des particules, on a identifié deux caractéristiques relatives à la réactivité physique et chimique des particules (la morphologie et la composition chimique de surface). D'abord, une méthode d'analyse d'images pour décrire la morphologie des particules a été introduite. Ensuite, l'applicabilité de la spectroscopie par photoélectron rayon-X (XPS) pour mesurer la composition chimique de surface des poudres céréalières a été on a examinée. A l'échelle des mécanismes, on a décrit et modalisé une étape importante des mécanismes d'agglomération des poudres céréalières. A l'échelle de procèdes, du couscous a été fabriqué à l'échelle pilote et ses paramètres de qualité ont été estimées. La relation entre les échelles a été évaluée en étudiant l'impact des caractéristiques des particules et de taux d'hydratation sur les mécanismes d'agglomération, le rendement d'agglomération, et la qualité finale de couscous. / Our research work is a preliminary study to investigate the impact that the surface characteristics of wheat powder particles have on their agglomeration mechanisms in the particular case of couscous production process. The objective of this research work was achieved by considering a multi scale approach: particle, mechanism, and process scale. On particle scale, we identified two characterizing factors of particles related to their physical and chemical reactivity (particles shape and surface chemical composition). We first presented a method based on image analyzing system to describe particles shape of wheat powders and then examined the applicability of X-ray photoelectron spectroscopy to measure the surface chemical composition of wheat powders. On mechanism scale, we described and modeled one stage of the wet agglomeration mechanisms of wheat powders. On process scale, we produced couscous in pilot scale and evaluated its quality parameters. The relationship between the scales was evaluated by studying the impact of particles characteristics and hydration rate on agglomeration mechanisms, agglomeration yield, and couscous quality.

A new process is being developed to produce graphite from prime coking coal. Coal is dissolved in dimethylformamide (DMF), on addition of sodium hydroxide. The minerals and undissolved coal are separated by centrifugation and filtration to give a solution (referred to as Refcoal solution or RCS). Over 90 wt % of the organic part of a flotation product, from the Tshikondeni mine, can be dissolved at temperatures ranging from room temperature to 135°C. The purified coal (referred to as Refcoal) and DMF need to be separated. the Refcoal to be coked and the DMF to be purified and recycled. This process should be as efficient as possible, whilst both products should be low in water content to minimise drying costs. The addition of water to the Refcoal solution causes precipitation to take place, forming a gel (referred to as Refcoal gel) liquid system. This mixture can be either centrifuged or filtered to give a denser gel, containing water, DMF and coal solids, and supernatant or filtrate, containing water and DMF. Different techniques and processes can be used to improve the separation of the DMF from the Refcoal by achieving a denser Refcoal gel: • Longer centrifugation times improve the density and therefore the separation, but this technique has its limits. • The use of low-temperature water improves the separation. • The use of syneresis could improve separation at a lower cost: heated standing tanks are used to expel the supernatant and therefore increase the density of the gel, thereby decreasing the required number of washing stages. • The addition of toluene at the beginning of a wash improved the removal of DMF by 20%, using centrifugation as separation method. • Pressure filtration gave a 20% improvement on centrifugation, with no additives. • The addition of toluene to the pressure filtration process gave another improvement of 15%, and after three stages the percentage of solids in the gel was 28%, the highest so far achieved. This method also resulted in the highest removal of DMF in the first stage (73% of the original DMF in the RCS was removed). Counter-current washing shows the greatest potential, using the least amount of water. The concentration of DMF in the wash solution, to gel the Refcoal solution, is a limitation of this process. If the concentration is too high, no gelling and therefore no separation can take place in the first stage. It is recommended that counter-current washing using pressure filtration should be investigated; however, this will be difficult on a laboratory scale due to the mass losses during transfers. / Dissertation (MEng (Chemical Engineering))--University of Pretoria, 2009. / Chemical Engineering / unrestricted