Integrated production-inventory control systems

Imperial Users onl

Together Yet Apart. The Institutional Rift Among Lebanese-Muslims in a South American Triple Frontier and Its Origins

On October 1988, the first mosque in the Triple Frontier between Argentina-Brazil-Paraguay was inaugurated. The name given to the mosque rekindled old and modern disputes amongst local Lebanese-Muslims in the region and led to the creation of parallel religious and cultural institutions. Based on oral history and local press, the article illustrates how the inauguration of the mosque and its aftermath reflected an Islamic dissension and Lebanese inter-religious and ethnic tensions that were "exported" to the Triple Frontier during the 1980s. The article also argues that the sectarian split among the leadership of the organized community, was not shared by the rank and file and did not reflect their daily practices.On October 1988, the first mosque in the Triple Frontier between Argentina-Brazil-Paraguay was inaugurated. The name given to the mosque rekindled old and modern disputes amongst local Lebanese-Muslims in the region and led to the creation of parallel religious and cultural institutions. Based on oral history and local press, the article illustrates how the inauguration of the mosque and its aftermath reflected an Islamic dissension and Lebanese inter-religious and ethnic tensions that were "exported" to the Triple Frontier during the 1980s. The article also argues that the sectarian split among the leadership of the organized community, was not shared by the rank and file and did not reflect their daily practices.En octubre de 1988 se inauguró la primera mezquita en la Triple Frontera entre Argentina, Brasil y Paraguay, cuyo nombre despertó disputas antiguas entre los distintos miembros de la comunidad libanesa musulmana de la región, lo que finalmente derivó en la creación de instituciones culturales y religiosas paralelas. Este artículo se basa tanto en historia oral como en la prensa local para ilustrar cómo es que la inauguración de la mezquita y sus consecuencias reflejaban en realidad un profundo desacuerdo entre dos escuelas del Islam, así como tensiones intra religiosas y étnicas del Líbano que fueron "importadas" a la Triple Frontera durante los años 80. Este artículo también argumenta que la brecha ocurrió entre los dirigentes comunitarios, pero no llegó a los miembros de la comunidad ni se vio reflejada en sus vidas diarias

Nature strikes back : naturalizing gender in some feminist discourses

La conocida "Lucha de sexos'" ha atravesado distintas etapas a través de los tiempos. La idoneidad de unos y otros para el ámbito público y privado respectivamente ha sido uno de los temas tradicionales. En algunos casos una serie de países han sido considerados "masculinos" o "femeninos" según el grado de participación de la mujer en la política y asuntos públicos. El presente ensayo retoma otro de los puntos de debate, el de la biología como categoría política y la naturalización del discurso femenino

Nature strikes back : naturalizing gender in some feminist discourses

La conocida "Lucha de sexos'" ha atravesado distintas etapas a través de los tiempos. La idoneidad de unos y otros para el ámbito público y privado respectivamente ha sido uno de los temas tradicionales. En algunos casos una serie de países han sido considerados "masculinos" o "femeninos" según el grado de participación de la mujer en la política y asuntos públicos. El presente ensayo retoma otro de los puntos de debate, el de la biología como categoría política y la naturalización del discurso femenino

Influence de la dissipation énergetique sur l'efficacité de la flottation à air dissous : analogie avec la floculation

Les flottateurs à air dissous sont classiquement dimensionnés à partir de deux paramètres: le rapport mA/mS des masses d'air et de solides en présence et le temps de contact entre phases. Une série d'essais effectués sur cinq différentes unités continues ou discontinues montre que ces seules variables opératoires ne suffisent pas à déterminer l'efficacité. De plus, l'extrapolation des données obtenues sur un floculateur discontinu conduirait à des besoins en air dissous considérables pouvant limiter le développement industriel. La dissipation d'énergie, habituellement négligée, peut être quantifiée par le gradient de vitesse tel qu'il a été introduit en théorie de la floculation. De plus, une analogie entre la capture bulles-particules et le processus de floculation des particules primaires sur les flocs déjà formés permet d'étendre les équations de vitesse de la floculation et d'obtenir un modèle cinétique où interviennent seulement le gradient de vitesse et la concentration de particules; ce modèle remplace avantageusement l'approche classique qui considère la flottation comme un processus du premier ordre par rapport aux particules. L'efficacité d'une cellule discontinue ou d'un floculateur piston est alors fonction du seul nombre de Camp. Les résultats montrent l'existence d'un intervalle optimal pour le gradient de vitesse, 3000 à 4000 s-¹, et pour le nombre de Camp 105 à 106. Le modèle devra être amélioré par introduction de la tension critique de mouillage des particules.Dissolved air flotation units are generally designed on the basis of two parameters: the mA/mS ratio of the air mass to the solid mass in reaction, and the contact time between the gas phase and the solid phase. The insufficiency of this approach, which neglects energy dissipation, is demonstrated.Five units, the efficiencies of which were quantified by turbidimetry, were operated with a bentonite suspension previously flocculated with WAC or ferric chloride. Batch flotator 1 was a commercial unit designed to evaluate flotation feasibility (Fig.1). Flotators 2 and 3 were used to establish flotation efficiency as a function of the mA/mS ratio in continuous operation (Figs. 2 and 3). The influence of contact time was determined with batch flotator 4 (Fig. 4). Continuous flotators 3 and 5 were identical rectangular reactors but the latter was designed to allow the injection of pressurized water through five different points (Fig. 3).Turbidity abatement increases as a function of mA/mS, reaching a plateau, the curve having a classical sigmoidal shape in batch or in continuous operation (Fig. 5). However the important air requirement (mA/mS=1) to attain 70% abatement would hamper industrial applications. The contact time is the residence time of the gas phase through a batch cell or the residence time of the solid phase through a continuous flotator. Its influence is displayed in Fig. 6 where a sigmoidal curve shows that a 100 second contact time is required to reach a significant abatement even with a low mA/mS of 0.1. However, flotator 3 operated with a 108 second contact time and 0.1 mA/mS ratio afforded only 40% abatement (Fig. 7). Efficiency is not therefore determined by the two classical parameters only but also by energy dissipation. The energetic conditions can be quantified by velocity gradient measurements, of classical use in flocculation; this parameter is 3100 s-¹ in flotator 3 and between 590 and 1670 s-¹ in flotator 4.Flotation kinetics are classically considered first-order with respect to the particle concentration (Eqn. 3). In fact there is an analogy between flotation and flocculation which allows one to extend the well-known flocculation kinetics (Eqn. 4) to the flotation process (Eqn. 5). The steadiness of the bubble concentration permits the derivation of Eqn. 6, which enables one to calculate the efficiency of a batch or a plug-flow reactor as a function of the Camp number Gt (Eqn. 9). In fact there is an optimum range of velocity gradients between 3000 and 4000 s-¹ and an optimum range of Camp number between 105 and 106 (Fig. 9). The difference with the range currently observed in flocculation could be explained by the contact efficiencies in each process and by the probable existence of two ranges of optimal conditions. The model accuracy can be verified and the rate constant calculated (Figs. 8 and 10). This approach should be extended by testing particles exhibiting different degrees of hydrophobicity

Élimination des colorants des eaux résiduaires de l'industrie textile par la bentonite et des sels d'aluminium

L'industrie textile utilise des colorants de synthèse toxiques qui polluent ses eaux résiduaires avec, parfois, des flux importants. Les procédés traditionnels les éliminent mal : ils sont peu iodégradables et la seule floculation, par exemple par des sels de fer, donne des résultats insuffisants. Or, en Algérie, la réutilisation agricole des eaux usées même industrielles est devenue une impérieuse nécessité. Le procédé proposé repose sur l'utilisation de sels d'aluminium ou, mieux encore, un polyhydroxyaluminium, associés à une bentonite de forage très fine présentant l'avantage d'être localement disponible et peu coûteuse. Quatre colorants ont été testés. Ils appartiennent à deux grandes familles : les colorants acides d'une part, Jaune Supranol 4GL et Vert Nylomine C8B et les colorants dispersifs d'autre part, Rouge Foron RDGL et Violet Foron S3RL. Les essais montrent que, si la bentonite seule ou les sels d'aluminium seuls présentent des efficacités insuffisantes, ces derniers du fait d'une mauvaise décantabilité des microflocs formés, l'association bentonite-aluminium permet d'éliminer les colorants en quasi totalité avec une excellente décantabilité. Les concentrations optimales à mettre en oeuvre sont relativement basses, de l'ordre de 13 mg/l de Al3+ et 250 mg/l de bentonite. Les coûts d'exploitation sont donc très raisonnables. Sur un effluent industriel réel, le procédé permet de passer d'une DCO de 770 mg/l à moins de 30 mg/l.The textile industry uses synthetic dyes, most of them being toxic. In Algeria, the agricultural reuse of treated wastewater, even of industrial origin, is becoming commonplace. It is therefore compulsory to drastically reduce pollutant fluxes. The presently operated conventional processes cannot meet the water quality requirements: bioelimination of dyes is negligible and flocculation with iron salts, as currently carried out in the SOITEX plant located in Tlemcen, Algeria, is not effective enough. The use of aluminum salts in the flocculation of such wastewaters is well known (FIESSINGER AND BERSILLON, 1977; LAHAV et al., 1978) but the resulting microflocs are not easily settleable. Bentonite, locally available at a low cost, can also eliminate micropollutants (LAHAV et al., 1978). Associated with polyhydroxyaluminum, it can reduce such compounds as benzene or toluene, favoring simultaneously the liquid-solids separation. This paper evaluates the treatability of dyes by bentonite associated with aluminum salts.All the runs were carried out in a 200 cm3 batch reactor, mechanically stirred and thermoregulated at 20·C. The main physico-chemical characteristics of the bentonite are given in Table 1. The flocculant was aluminum chloride, previously neutralized with sodium hydroxide (mass ratio OH-/Al=1.85). The solutions were used immediately or left to polymerize during 6 days leading to polyhydroxyaluminum PHAl (LAHAV et al., 1978). When the reactor was operated with bentonite and aluminum, the mass ratio Al/bentonite was maintained at 53.10-3 (KACHA, 1994). Four dyes belonging to two main families were tested: Supranol Yellow 4GL and Nylomine Green (acid dyes) and Foron Red RDGL and Foron Violet S3RL (dispersive dyes). Their concentrations were obtained by spectrophotometry.Bentonite alone does not induce a significant abatement excepted for low pH values around 4 (Figs. 1 and 2). Dye elimination appears to require a previous protonation step followed by cation exchange. The equilibrium can be modeled by a Freundlich equation (Fig. 3 and Table 2). The dyes can also be eliminated by aluminum salts alone (Fig. 4). The efficiency is then better with polyhydroxyaluminum, i.e. more than 90 % of the initial concentration is removed. Nevertheless, the dyes abatement probably results from an adsorption or chemical reaction on microflocs which are not easily settleable. By assuming that all the aluminum ions are precipitated as aluminum hydroxide, the equilibrium is modeled by the Langmuir equation which would indicate a monolayer adsorption (Fig. 5). When the reactor is operated with bentonite and aluminum salts, dye abatement is nearly complete and the liquid-solids separation is particularly efficient (Figs. 6 and 7). The best results are obtained with PHAl but the use of the monomer can be sufficient. The required concentrations are relatively low and the process is then economically feasible (Table 3). However, the experimental data can no longer be modeled by the Freundlich equation nor by the Langmuir equation. When the aluminum salts react alone with the dyes, the conductance displayed against the aluminum concentration shows two straight lines of different slopes (Fig. 8). The abscissa of the points where the slopes change are proportional to the initial dye concentration, suggesting a chemical reaction between the dye and the aluminum salts (Fig. 9). However, the final pH value lies at the limit value of aluminum hydroxide precipitation; an adsorption on aluminum hydroxide or an aluminum salt precipitation cannot then be assumed. In presence of bentonite, such changes of slope are not observed and, moreover, the final pH value does not correspond either to a precipitation value (Figs. 11 and 12). At this stage, a comprehensive mechanism cannot thus be proposed. However, the process using bentonite/PHAl is particularly efficient and easy to operate (Fig. 13 and Table 3). The results were confirmed with a true industrial effluent, the Chemical Oxygen Demand (COD) of which was reduced from 770 mg/l to less than 30 mg/l (Fig. 14). As a matter of comparison, the actual process, which includes an activated sludge treatment followed by an iron sulfate/lime flocculation, leads to an effluent containing only 140 mgCOD/l

Les Women’s Studies aux États‑Unis.

Issues du mouvement des femmes des années 70, les Women’s Studies avaient pour objectif de prolonger la critique de la place faite aux femmes dans la société par la critique des discours légitimant leur exclusion. Dans un contexte général de développement des études sur les minorités, les féministes universitaires ont obtenu, à une large échelle, avec l’appui des étudiantes, la création d’enseignements sur les femmes et de Women’s Studies interdisciplinaires. Les premiers cours apparurent ent..

Les Women’s Studies aux États‑Unis.

Issues du mouvement des femmes des années 70, les Women’s Studies avaient pour objectif de prolonger la critique de la place faite aux femmes dans la société par la critique des discours légitimant leur exclusion. Dans un contexte général de développement des études sur les minorités, les féministes universitaires ont obtenu, à une large échelle, avec l’appui des étudiantes, la création d’enseignements sur les femmes et de Women’s Studies interdisciplinaires. Les premiers cours apparurent ent..