Fragmentation and immiserising specialisation : the case of the textile and clothing sector

With production activity tending rapidly towards international fragmentation, this study examines the consequences for labour countries of the forms of specialisation brought about by fragmentation processes. It further addresses the risk that fragmented sectors may become excluded from greater developments within the manufacturing industry as a whole. An empirical analysis using panel data reveals that, contrary to expectation, the textile and clothing sector in labour countries does not always reap the positive benefits of this form of international trade integration. Rather, we observe a phenomenon of immiserising specialisation, due to a drop in relative wages within this sector.offshoring ; outsourcing ; fragmentation ; immiserising specialisation ; relative wages ; textile and clothing sector

Fragmentation and immiserising specialisation : the case of the textile and clothing sector

Working Paper GATE 2010-03With production activity tending rapidly towards international fragmentation, this study examines the consequences for labour countries of the forms of specialisation brought about by fragmentation processes. It further addresses the risk that fragmented sectors may become excluded from greater developments within the manufacturing industry as a whole. An empirical analysis using panel data reveals that, contrary to expectation, the textile and clothing sector in labour countries does not always reap the positive benefits of this form of international trade integration. Rather, we observe a phenomenon of immiserising specialisation, due to a drop in relative wages within this sector

From colloidal dispersions to colloidal pastesthrough solid–liquid separation processes

Solid–liquid separation is an operation that starts with a dispersion of solid particles in a liquid and removes some of the liquid from the particles, producing a concentrated solid paste and a clean liquid phase. It is similar to thermodynamic processes where pressure is applied to a system in order to reduce its volume. In dispersions, the resistance to this osmotic compression depends on interactions between the dispersed particles. The first part of this work deals with dispersions of repelling particles, which are either silica nanoparticles or synthetic clay platelets, dispersed in aqueous solutions. In these conditions, each particle is surrounded by an ionic layer, which repels other ionic layers. This results in a structure with strong short-range order. At high particle volume fractions, the overlap of ionic layers generates large osmotic pressures; these pressures may be calculated, through the cell model, as the cost of reducing the volume of each cell. The variation of osmotic pressure with volume fraction is the equation of state of the dispersion. The second part of this work deals with dispersions of aggregated particles, which are silica nanoparticles, dispersed in water and flocculated by multivalent cations. This produces large bushy aggregates, with fractal structures that are maintained through interparticle surface– surface bonds. As the paste is submitted to osmotic pressures, small relative displacements of the aggregated particles lead to structural collapse. The final structure is made of a dense skeleton immersed in a nearly homogeneous matrix of aggregated particles. The variation of osmotic resistance with volume fraction is the compression law of the paste; it may be calculated through a numerical model that takes into account the noncentral interparticle forces. According to this model, the response of aggregated pastes to applied stress may be controlled through the manipulation of interparticle adhesion

Impact de la densité de semis et de la fertilisation azotée sur le développement de Rumex obtusifolius L. en cultures de céréales d'hiver conduites en agriculture biologique

The control of Rumex obtusifolius L. (broad-leafed dock) is very important in organic farming systems. Indeed, concerns about managing this weed without the use of herbicides is one of the major factors limiting the uptake of these systems by conventional farmers. Against this backround, we analyzed the impact of two management practices on the development of R. obtusifolius populations in two winter cereal trials: spelt (triticum spelta [L.] thell.) and triticale (xtriticosecale [A.Camus]Wittm.). The management factors were sowing density (SD) and nitrogen fertilization (NF) at the tillering stage. The results showed that and increase in SD and NF led to stronger crop growth and better soil coverage by the end of sping, demonstrated by a significant decrease in photosynthetic active radiation (PAR) at soil level. However, although there was an SD effect, it was too weak in April to restrict an increase in R. obtusifolius populations through the recruitment of new R. obtusifulius plants. An increase in R. obtusifolius population density was also linked to an increase in the NF level, illustrating the nitrophilic character of this weed. Although an increase in SD and NF at the tillering stage led to a higher canopy density, these two practices failed to reduce R. Obtusifolius density in the cereal crops. Nevertheless, cereal yields were shown to be maintained or improved. Our results indicate that, even when combining weed harrowing and some cultural weed control methods, this perennial weed is difficult to control

Determination of the effect of geological reservoir variability on carbon dioxide storage using numerical experiments

International audienceThe simulations of carbon dioxide storage in sedimentary reservoirs model the fluid and gas flow and the chemical reactions which occur between the minerals (calcite and dolomite) and the injected CO2 [André et al. (2007) Energy Convers. Manage. 48, 1782-1797; Gunter et al. (1999) Appl. Geochem. 4, 1-11]. However because of the lack of data, these reservoirs are always partially known and the fitted variograms of petrophysical and mineralogical quantities are approximate. The aim is to quantify the impact of uncertainties on reservoir characteristics on the storage predictions. We focus on two operational parameters: the quantity of the stored carbon dioxide and the mean variation of the porosity. Two sources of uncertainties are examined: the draw dispersion and the approximation on the variogram parameters. To study the influence of the draw dispersion, variogram parameters are kept fixed and different simulations are run; the associated variance on the operational parameters then has the meaning of a repeatability error. In the second case, a sensibility analysis is carried out to study the influence of variogram parameters variations (sill, range, nugget effect) on the CO2 storage. The chosen methodology is the designs of experiments. The simulations are carried out using reactive transport software. The studied carbonated reservoir is built in reference to the Dogger formation of Paris Basin (France) [Diedro (2009) Thèse, École Nationale Supérieure des Mines de St-Étienne]. This reservoir is composed of several minerals, some of them being disposed in spots. The results show that the impact of the draw dispersion remains lower than the impact of the variogram parameters. The effect of the size of the dolomite spots within the rock on the stored carbon dioxide is to be noticed. Larger spots of the dolomite field with low concentration lead to a greater precipitation of carbonate and reduction of porosity than little spots with higher concentrations. The interaction between the sill and the range of the variogram of the initial dolomite concentration is also important. The initial calcite concentration has a slight influence only on the average porosity in the reservoir. Except for the variations of the size of the dolomite spots within the rock, small variations on the variogram parameters of the mineralogical concentration do not involve important modification of stored carbon nor of the final porosity.Détermination de la variabilité des réservoirs géologiques sur le stockage du CO2 par la méthodologie des plans d'expériencesDans le contexte de l'étude du stockage géologique du dioxyde de carbone dans les réservoirs sédimentaires, les simulations tentent de reproduire le plus fidèlement possible les écoulements fluides et gaz, ainsi que les réactions chimiques entre les minéraux (calcite et dolomite) et le CO2 injecté [André et al. (2007) Energy Convers. Manage. 48, 1782-1797; Gunter et al. (1999) Appl. Geochem. 4, 1-11]. Cependant, les réservoirs étudiés sont généralement mal connus. Les observations sont peu nombreuses et par suite les variogrammes des propriétés pétrophysiques et minéralogiques sont approchés. L'article vise à quantifier les incertitudes sur les prévisions de stockage du CO2. Nous examinons en particulier l'effet des incertitudes sur deux paramètres opérationnels : la quantité de dioxyde de carbone stockée et la variation moyenne de la porosité. Les sources d'incertitudes retenues sont la variabilité du tirage (dispersion statistique) et l'incertitude sur les paramètres du variogramme. Pour examiner la variabilité liée au tirage, les paramètres du variogramme sont fixés et plusieurs simulations sont réalisées, ce qui fournit une distribution de valeurs pour les paramètres opérationnels et permet le calcul d'une variance, apparentée à une variance de répétabilité. Dans le second cas, une analyse de sensibilité permet d'examiner l'influence des paramètres des variogrammes (palier, portée, effet de pépite) sur le stockage du CO2. À cet effet, la méthodologie des plans d'expériences est utilisée. Les simulations sont réalisées à l'aide d'un logiciel de transport réactif. Le gisement étudié est construit en référence à la formation du Dogger du Bassin de Paris (France) [Diedro (2009) Thèse, École Nationale Supérieure des Mines de St-Étienne]. Les réservoirs simulés comportent plusieurs minéraux avec pour certains des taches de dolomite. Les résultats montrent que la variabilité du tirage reste inférieure à l'effet dû à l'incertitude sur les paramètres du variogramme. L'effet de la taille des taches de dolomite sur le dioxyde de carbone a été également mis en évidence. Les grandes taches à concentration moyenne favorisent une .importante précipitation de carbonate entrainant ainsi une baisse de la porosité moyenne contrairement à des taches plus petites mais à plus forte concentration. L'interaction entre le palier et la portée du variogramme de la dolomite initiale est également importante. La concentration initiale de calcite n'a d'influence que sur la porosité moyenne dans le réservoir et cette influence reste modeste. De petites variations sur les autres paramètres du variogramme de la concentration minéralogique modifient peu le carbone stocké ou la porosité finale