WorldWideScience

Sample records for atmospherique urbaine agglomeration

  1. Evaluation of sanitary impact of urban air pollution. Agglomeration of Perigueux impact at short and long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Agglomeration de Perigueux impact a court et long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-15

    A health impact assessment of air pollution based on the I.n.V.S. guidelines has been conducted in Perigueux according to the regional Plan for the quality of air in the region of Aquitaine. It has been carried out in 5 cities homogeneously exposed, belonging to Perigueux agglomeration, representing a study population of 52,948 inhabitants. Atmospheric pollution indicators analysed are ozone, nitrogen dioxide and particles having diameter below 10 {mu}m. Short-term impact of atmospheric pollution has been estimated in term of mortality (total, cardiovascular and respiratory mortality) and on hospital intakes (for respiratory, cardiovascular and cardiac reasons) attributable to air pollution. Long term impact was also assessed by the number of deaths due to atmospheric pollution. In 2001, the atmospheric pollution has directly been responsible in the studied area for 5 anticipated deaths. A decrease by 25% of the pollutants could allow avoiding half of the premature deaths and hospital intakes attributable to air pollution. Concerning long term effects, a decrease by 5 {mu}g/m{sup 3} of the annual mean of P.M.10 could allow avoiding 10 deaths per year. These results should be interpreted with care because of the limits of the method. However, they show that air pollution can have an impact even in a small agglomeration like Perigueux, since everyone is exposed to air pollution. They also suggest that a policy of atmospheric pollution reduction only based on not exceeding the standard levels would not have the expected benefits on the public health point of view. To decrease at the source the every day and total pollutants emissions would be more efficient. (author)

  2. Evaluation of sanitary impact of urban air pollution. Agglomeration of Bayonne impact at short and long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Agglomeration de Bayonne impact a cour et long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-06-15

    A health impact assessment of air pollution based on the I.n.V.S. guidelines has been conducted in Bayonne according to the regional Plan for the quality of air in the region of Aquitaine. It has been carried out in 16 cities homogeneously exposed, belonging to Bayonne agglomeration, representing a study population of 148,742 inhabitants. Atmospheric pollution indicators analyzed are ozone, nitrogen dioxide and particles having diameter below 10 {mu}m. Short-term impact of atmospheric pollution has been estimated in term of mortality (total, cardiovascular and respiratory mortality) and on hospital intakes (for respiratory, cardiovascular and cardiac reasons) attributable to air pollution. Long term impact was also assessed by the number of deaths due to atmospheric pollution. In 2001, the atmospheric pollution has directly been responsible in the studied area for 20 anticipated deaths. A decrease by 25% of the pollutants could allow avoiding half of the premature deaths and hospital intakes attributable to air pollution. Concerning long term effects, a decrease by 5 {mu}g/m{sup 3} of the annual mean of PM{sub 10} could allow avoiding 32 deaths per year. These results should be interpreted with care because of the limits of the method. However, they show that air pollution impact is non negligible even in a small agglomeration like Bayonne, since everyone is exposed to air pollution. They also suggest that a policy of atmospheric pollution reduction only based on not exceeding the standard levels would not have the expected benefits on the public health point of view. To decrease at the source the everyday and total pollutants emissions would be more efficient. (author)

  3. Evaluation of sanitary impact of urban air pollution. Agglomeration of Agen impact at short and long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Agglomeration d'Agen impact a court et long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    A health impact assessment of air pollution based on the I.n.V.S. guidelines has been conducted in Agen according to the regional Plan for the quality of air in the region of Aquitaine to assess short term effects of pollutants on morbidity (hospital admissions in 2002) and mortality (deaths in 2001), and long-term effects on mortality. This study is based on the four standardised steps of health risk assessment. It has been carried out in 8 cities homogeneously exposed, belonging to Agen agglomeration, representing a study population of 60,515 inhabitants. Atmospheric pollution indicators analysed are ozone and particles having diameter below 10 {mu}m. Short-term impact of atmospheric pollution has been estimated in term of mortality (total, cardiovascular and respiratory mortality) and on hospital intakes (for respiratory, cardiovascular and cardiac reasons) attributable to air pollution.Long-term impact was also assessed by the number of deaths due to atmospheric pollution. In 2001, the atmospheric pollution has directly been responsible in the studied area of 4 anticipated deaths, including 2 for cardiovascular reason. A decrease by 25% of the pollutants could allow avoiding 2 premature deaths per year among the 4 attributable to air pollution. Concerning long-term effects, a decrease by 5 {mu}g/m{sup 3} of the annual mean of P.M.10 would allow avoiding 11 premature deaths per year. The results of this study should be interpreted with care because of the limits of the method. However, they show that air pollution can have a health impact even in a small city like Agen, since everyone is exposed to air pollution. (author)

  4. Evaluation of sanitary impact of urban air pollution. Agglomeration of Bordeaux impact at short and long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Agglomeration de Bordeaux impact a cour et long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-06-15

    A health impact assessment of air pollution based on the I.n.V.S. guidelines has been conducted in Bordeaux area. Atmospheric pollution indicators analyzed were ozone, nitrogen dioxide and particles having diameter below 10 {mu}m. Short term impact of atmospheric pollution has been estimated in term of mortality (total, cardiovascular and respiratory mortality) and hospital admissions (for respiratory, cardiovascular and cardiac reasons) attributable to air pollution. Long-term impact was also assessed by the number of deaths due to atmospheric pollution. The study has been carried out in 22 cities homogeneously exposed belonging to Bordeaux agglomeration, representing a study population of 604,238 inhabitants. In 2001, the atmospheric pollution has directly been responsible in the studied area of 56 anticipated deaths, including half for cardiovascular reasons and 7 for respiratory reasons. Regarding morbidity, 29 hospital admissions for respiratory disease were attributable to air pollution in 2002, including two-thirds among elderly people (aged 65 years and over). Further more, 81 hospitalizations for cardiovascular diseases that occurred in 2002 were attributable to air pollution, including 27 for cardiac reasons. A decrease by 25% of the pollutants could have allowed avoiding about half of the premature deaths and hospital intakes attributable to air pollution. Concerning long term effects, about 200 annual deaths are attributable to chronic exposure to air pollution, and a decrease by 5{mu}g/m{sup 3} of the annual mean of PM{sub 10} could allow avoiding half of these deaths. The results have to be interpreted with care because of the limits of the H.I.A. method. However, they show that air pollution has a non negligible impact even in a city like Bordeaux where target values are mostly respected. They also show that reducing air pollution can have a significant impact in term of mortality and morbidity. However, a policy of atmospheric pollution reduction

  5. Evaluation of sanitary impact of urban air pollution. Agglomeration of Pau impact at short and long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Agglomeration de Pau impact a cour et long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    A health impact assessment of air pollution based on the I.n.V.S. guidelines has been conducted in Pau according to the regional Plan for the quality of air in the region of Aquitaine. Short-term effects of pollutants on morbidity (hospital admissions in 2002) and mortality (deaths in 2001) have been estimated. Long-term effect on mortality was also assessed. This study is based on the four standardised steps of health risk assessment. It has been carried out in twenty-nine cities homogeneously exposed, belonging to Pau agglomeration, i.e. a study population of about 150,000 inhabitants. Atmospheric pollution indicators analysed are ozone, nitrogen dioxide, and particles having diameter below 10 {mu}m. Short-term impact of atmospheric pollution has been estimated in term of mortality (total, cardiovascular and respiratory mortality) and on hospital intakes (for respiratory, cardiovascular and cardiac reasons) attributable to air pollution. Long term impact was also assessed by the number of deaths due to atmospheric pollution. In 2001, the atmospheric pollution has directly been responsible in the studied area for 17 anticipated deaths, including 7 for cardiovascular reason and 2 for respiratory reason. Concerning morbidity, it generated 20 hospital admissions for cardiovascular reason in 2002, 11 for cardiac reason, and 7 for respiratory reason among elderly people. Regarding long-term health gains, an annually decrease according to the European standards levels of 2010 could allow avoiding 12 deaths per year, and a decrease by 30% of the pollutants could allow avoiding 33 premature deaths per year. This study shows that, even if the relative risks associated to air pollution are quite low, the number of attributable cases is non negligible since everyone is exposed to air pollution. It also shows that a policy of atmospheric pollution reduction only based on not exceeding the standard levels would not have the expected benefits on the public health point of view

  6. L'agglomeration oranaise jeux d'acteurs et dynamique urbaine ...

    African Journals Online (AJOL)

    L'agglomération oranaise connaît actuellement une croissance urbaine importante entraînant des évolutions économiques et socioculturelles considérables. Partant de là, une question nous interpelle: Quels sont les mécanismes à la base de la dynamique d'urbanisation, les processus de restructuration et de ...

  7. Intermodalite et developpement urbain dans l'agglomeration d'alger ...

    African Journals Online (AJOL)

    Face à l'échec rejeté de toutes les politiques adoptées dans le processus du développement urbain de la ville d'Alger depuis la période coloniale et jusqu'à nos jours, force est de constater que les différents instruments d'urbanisme mis en place n'arrivent pas à venir à bout de toutes les contraintes de son site qui est très ...

  8. AGGLOMERATION

    OpenAIRE

    Mori, Tomoya

    2017-01-01

    This article provides a review of selected researches on the mechanism, spatial scale and spatial distribution of economic agglomeration. It starts with a classification of the existing models of agglomeration in terms of the sources of agglomeration force suggested by the Spatial Impossibility Theorem by Starrett (1978). It then discusses the tension between economies and diseconomies of agglomeration. Finally it briefly touches on the measures of agglomeration and dynamic aspect of agglomer...

  9. Evaluation of urban air pollution impact. Agglomeration of Toulon impact at short and long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Agglomeration de Toulon impact a cour et long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    A health impact assessment of air pollution based on the I.n.V.S. guidelines has been conducted in Toulon according to the Regional Plan for the quality of air in the region of Provence-Alpes-Cote d Azur. Short-term effects on morbidity (hospital admissions) and mortality and long-term effects on mortality were estimated. Four cities were included in the study area: Toulon, La Garde, La Seyne-sur-mer and La Valette-du-Var (population: 267.808 inhabitants. Two periods of study have been defined: 1999 for the mortality analysis and 2000 for the morbidity analysis and the long- term effects. For 1999, number of advanced deaths due to air pollution is around 84 for total mortality including 30 deaths due to cardio-vascular diseases and 10 deaths due to respiratory diseases. The different scenarios of air pollution reduction showed that the most effective ones are those which lead to reduce of 25% the mean of the involved pollutant. Regarding long-term effects, the different scenario showed that the respect of the European Community limits value for the year 2010 would allow to avoid 118 deaths over one year. Results showed that air pollution are even resulting in health effects for some levels of pollution lower than current French limits. The most effective actions should therefore associate reduction of the source emissions on a daily basis and decrease of the over-limits levels of pollution. (author)

  10. Evaluation of sanitary impact of urban air pollution. Montpellier area impact at short and long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Zone de Montpellier impact a court et long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The assessment of the health impact of urban atmospheric pollution in Montpellier agglomeration has been carried out as part of the development of atmosphere protection plan. The study, based on the four standardised steps of health risk assessment, has two objectives. First of all, it aims at assessing the short-term impact of atmospheric pollution on mortality (total, cardiovascular and respiratory mortality) and on hospital intakes (for respiratory, cardiovascular and cardiac reasons). Second, the long-term impact is assessed by the number of deaths due to atmospheric pollution. On the other part, the computation of the expected health gain, as a function of different scenarios of atmospheric pollutants reduction, can allow to plan air quality improvement measures. The assessment of atmospheric pollution impact has been carried out in eleven cities, homogeneously exposed, belonging to Montpellier agglomeration (Castelnau-le-Lez, Clapiers, Le Cres, Grabels, Jacou, Juvignac, Montferrier-sur-Lez, Montpellier, Saint-Clement-de-Riviere, Saint- Jean-de-Vedas, Vendargues). It is based on the analysis of mortality figures during two years (1999 and 2000) and of hospital intakes during four years (from 1999 to 2002). The studied population is made up 288.059 inhabitants. Atmospheric pollution indicators analysed are ozone, nitrogen dioxide, sulphur dioxide and particles having diameter below 10 {mu}m. Every year, the atmospheric pollution is directly responsible in the studied area of 34 anticipated deaths, among including 13 for cardiovascular reason and 4 for respiratory reason. For morbidity, it generates every year 79 hospital admissions for cardiovascular reason, 15 for cardiac reason, 9 for respiratory reason for older than 65 years old people and 4 for 15-64 years old people. Older than 65 years old people are proportionally more impacted. These events could theoretically be avoided with pollution levels in the order of those reached the less polluted days. Health

  11. Heterogeneous Agglomeration

    OpenAIRE

    Faggio, G; Silva, O; Strange, W.C.

    2017-01-01

    Many prior treatments of agglomeration either explicitly or implicitly suppose that all industries agglomerate for the same reasons, with traditional Marshallian (1890) factors affecting all industries similarly. An important instance of this approach is the extrapolation of the agglomeration experience of one key sector or cluster to the larger economy. Another is the pooling of data to look at common tendencies in agglomeration. This paper uses UK establishment level data on coagglomeration...

  12. Evaluation of sanitary impact of urban air pollution. Agglomeration of Orleans and Tours impact at short and long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Agglomeration d'Orleans et de Tours impact a cour et long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    An health impact assessment of air pollution based on the I.n.V.S. guidelines has been conducted in Orleans and Tours according to the regional Plan for the quality of air in the region of Centre. Short-term effects on morbidity (hospital admissions in 2002 and 2003) and mortality. Long-term mortality was also estimated. The estimated numbers of hospitalizations are: Orleans: 11 [2-23]* for respiratory admissions and 26 [16-36]* for cardiovascular admissions; Tours: 11 [3-22]* for respiratory admissions and 34 [20-48]* for cardiovascular admissions. For long-term mortality the estimated impact is 59 [36-84]* in Orleans and 61 [37-86]* in Tours. The different scenarios of air pollution reduction showed that the most effective ones are those which lead to reduce of 25% the mean of the involved pollutant. Results showed that air pollution are even resulting in health effects for some levels of pollution than current limits. The most effective actions should therefore associate reduction of the source emissions on a daily basis and decrease of the over-limits levels of pollution. (author)

  13. Evaluation of sanitary impact of the urban air pollution. Agglomeration of Angouleme, Niort and Poitiers impact at short and long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Agglomeration d'Angouleme, Niort et Poitiers impact a cour et long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    An health impact assessment of air pollution based on the I.n.V.S. guidelines has been conducted in Angouleme, Niort and Poitiers according to the Regional Plan for the quality of air in the region of Poitou- Charentes. Short-term effects on morbidity (hospital admissions in 2001 and 2002) and mortality were estimated. Long-term effects due to air pollution on mortality were also evaluated. The estimated numbers of hospitalizations for cardiovascular and respiratory admissions due to air pollution are 19 in Angouleme, 11 in Niort and 19 in Poitiers. For long-term mortality the estimated impact is 25 in Angouleme, 19 in Niort and 23 in Poitiers. The different scenarios of air pollution reduction showed that the most effective ones are those which lead to reduce of 25% the mean of the involved pollutant. Results showed that air pollution are even resulting in health effects for some levels of pollution lower than current limits. The most effective actions should therefore associate reduction of the source emissions on a daily basis and decrease of the over-limits levels of pollution. (author)

  14. Natural agglomeration

    OpenAIRE

    Picard, Pierre; Tabuchi, Takatoshi

    2003-01-01

    This paper considers the racetrack economic approach, where manufacturing activities are distributed continuously. We seek constant-access equilibria and show that smooth equilibrium distributions are always unstable for almost all transport cost functions, whereas agglomeration in 1 or 2 atomic cities is stable for any economic parameters given regular transport costs, such as linear transport costs.

  15. La nouvelle critique urbaine

    Directory of Open Access Journals (Sweden)

    Christian Lefèvre

    2010-11-01

    Full Text Available La critique urbaine est un art global. Dans la conception qu’en illustre le parcours de Bernard Jouve, dont ce numéro porte témoignage, elle outrepasse plusieurs frontières à la fois. Son premier ouvrage concerne précisément la relation entre frontière (nationale et les enjeux urbains, en 1994. Dès de sa thèse, il aborde déjà la ville par sa matérialité et par les rapports de force qui la constituent comme telle. Ce souci constant d’aller de la technique au social, par un politique qui ne se...

  16. Sanitary impact of the particulate atmospheric urban pollution; Impact sanitaire de la pollution atmospherique urbaine particulaire

    Energy Technology Data Exchange (ETDEWEB)

    Sentissi, M.

    1999-03-22

    The pollution of particulates origin is one of the principle actual problem relative to air quality. In France, the fine particulates come from industry and automobile traffic, especially, the diesel vehicles. The most worrying characteristic is their fineness, that allow them to stay in suspension during a long time and penetrate into pulmonary alveoli, with toxic elements at their surface such metals, acids, polycyclic aromatic hydrocarbons. The objective of this work is to take stock of epidemiology and toxicology studies evaluating the sanitary impact of particulates in suspension. (N.C.)

  17. Social Agglomeration Externalities

    OpenAIRE

    Borck, Rainald

    2005-01-01

    This paper examines social agglomeration externalities. Using survey data from the German Socio-Economic Panel, I examine the link between city size and different measures of consumption, social interaction and social capital. Further, using responses to satisfaction questions, I analyse whether individuals are compensated for diseconomies of agglomeration by positive agglomeration externalities in other areas. This equilibrium hypothesis cannot be rejected.

  18. Les politiques urbaines en Tunisie

    Directory of Open Access Journals (Sweden)

    Mustapha Ben Letaief

    2008-12-01

    Full Text Available En Tunisie, l’action publique en matière d’aménagement urbain connaît des mutations sensibles dans un contexte qu’on pourrait assimiler aux transitions post-keynésiennes. En effet, en 1994, la population urbaine tunisienne représentait 5,4 millions soit 61% de l’ensemble de la population. En 2015, les villes tunisiennes regrouperaient 68,5% de la population totale environ. Cette croissance urbaine consommera l’équivalent de la moitié de l’espace urbain existant au milieu des années quatre-vingt-dix. Ainsi, les villes tunisiennes doivent faire face à des besoins nouveaux en matières d’aménagement de terrains urbains, de constructions de logements, d’infrastructure et d’équipement.En même temps, depuis le milieu des années quatre-vingts, face aux difficultés budgétaires engendrées par la rétraction de ses ressources, la crise du modèle keynésien de gestion publique étroitement lié à un certain fordisme périphérique et le retour en force des logiques libérales préconisant la réhabilitation des mécanismes de régulation par marché, le désengagement de l’Etat et la redistribution des rôles entre secteur public et initiative privée, l’Etat tunisien a adopté une politique d’ajustement libéral et d’ouverture économique impliquant une insertion dans le mouvement de globalisation. La question de la politique urbaine s’inscrit, désormais, dans cette logique et se décline en une politique dite de mise à niveau des villes tunisiennes tout en cherchant un certain désengagement de l’Etat.La conjugaison de ces trois phénomènes, de forte croissance urbaine, de désengagement et d’insertion dans la globalisation économique a engendré une mutation des modes de gouvernance urbaine et des logiques qui les régissent et qui s’avèrent contradictoires et difficilement conciliables conjuguant culture autoritaire, démarche partenariale et faible décentralisation.  Ce texte tente de d

  19. Growth and Agglomeration

    OpenAIRE

    Philippe Martin; Gianmarco Ottaviano

    1996-01-01

    This paper presents a model in which growth and geographic agglomeration of economic activities are mutually self reinforcing processes. Industrial agglomeration in one location spurs growth because it reduces the cost of innovation in that location through a pecuniary externality due to transaction costs. Growth fosters agglomeration because as the sector at the origin of innovation expands, new firms tend to locate close to this sector. The model can be interpreted as illustrating one mecha...

  20. Agglomeration and Markup

    OpenAIRE

    Lu, Yi; Tao, Zhigang; Yu, Linhui

    2011-01-01

    Agglomeration brings costs (e.g., intensified local competition) as well as benefits (e.g., knowledge spillover). It is important to examine the net impact of agglomeration to understand the geographic distribution of economic activities. In this study, we use firm markup (defined as the ratio of price over marginal cost) to capture the net impact of agglomeration. Using data from Chinese manufacturing firms in the 1998-2005 period, we first recover the markup ratio for each firm following De...

  1. Defining urban agglomerations to detect agglomeration economies

    CERN Document Server

    Cottineau, Clementine; Hatna, Erez; Arcaute, Elsa; Batty, Michael

    2016-01-01

    Agglomeration economies are a persistent subject of debate among economists and urban planners. Their definition turns on whether or not larger cities and regions are more efficient and more productive than smaller ones. We complement existing discussion on agglomeration economies and the urban wage premium here by providing a sensitivity analysis of estimated coefficients to different delineations of urban agglomeration as well as to different definitions of the economic measure that summarises the urban premium. This quantity can consist of total wages measured at the place of work, or of income registered at the place of residence. The chosen option influences the scaling behaviour of city size as well as the spatial distribution of the phenomenon at the city level. Spatial discrepancies between the distribution of jobs and the distribution of households at different economic levels makes city definitions crucial to the estimation of economic relations which vary with city size. We argue this point by regr...

  2. Description of agglomerate growth

    NARCIS (Netherlands)

    Schaafsma, S.H; Vonk, P; Segers, P; Kossen, N.W F

    1998-01-01

    Wet agglomeration processes have predominantly been investigated by changing operation variables of process-scale experiments. So far, most fundamental work concentrated on the strength of the liquid bonds in the agglomerate and its relation to the process. Previous studies on the relationship

  3. Imaginaire sonore et environnement urbain

    OpenAIRE

    Chelkoff, Grégoire

    1996-01-01

    National audience; C'est en examinant les relations spécifiques qu'ils construisent avec l'environnement sensible quenous proposons d'aborder les objets construits et plus particulièrement ici les banlieues. En montrant quelquesfacettes de l'environnement sonore des banlieues, nous recherchons des pistes de réflexion et d'action à partird'un composant important mais souvent ignoré des ambiances urbaines. Nous nous demandons notammentcomment se fabrique le milieu sonore en banlieue, quels mode...

  4. Agglomeration and Firm Turnover

    OpenAIRE

    Marjan Nasir

    2013-01-01

    The geographic and industrial concentration of firms affects firm turnover, as highlighted in research on industrial organization. This study conducts a firm-level analysis to determine the impact of agglomeration on firm entry and exit in domestic industries in Punjab, Pakistan. The study also illustrates how some industries exist in clusters while others are highly dispersed. The results suggest that firm entry and exit is higher in highly agglomerated industries.

  5. Agglomeration of ceramic powders

    Science.gov (United States)

    Cawley, James D.; Larosa, Judith; Dirkse, Fredrick

    1989-01-01

    A research program directed at a critical comparison of numerical models for power agglomeration with experimental observations is currently underway. Central to this program is the quantitative characterization of the distribution of mass within an agglomerate as a function of time. Current experiments are designed to restrict agglomeration to a surface, which is oriented perpendicular to the force of gravity. These experiments are discussed with reference to: their significance to ceramic processing; artifacts which may be avoided in microgravity experiments; and the comparison of information available in real space (from optical microscopy) to that in reciprocal space (from light scattering). The principle machine requirement appears to be a need to obtain information at small scattering angles.

  6. Modeling of urban atmospheric pollution and impact on health; Modelisation de la pollution atmospherique urbaine et impact sur la sante

    Energy Technology Data Exchange (ETDEWEB)

    Myrto, Valari

    2009-10-15

    The goal of this dissertation, is to develop a methodology that provides an improved knowledge of the associations between atmospheric contaminant concentrations and health impact. The propagation of uncertainties from input data to the output concentrations through a Chemistry Transport Model was first studied. The influence of the resolutions of meteorological parameters and emissions data were studied separately, and their relative role was compared. It was found that model results do not improve linearly with the resolution of emission input. A critical resolution was found, beyond which model error becomes higher and the model breaks down. Based on this first investigation concerning the direct down scaling, further research focused on sub grid scale modeling. Thus, a statistical down scaling approach was adopted for the modeling of sub grid-scale concentration variability due to heterogeneous surface emissions. Emission fractions released from different types of sources (industry, roads, residential, natural etc.) were calculated from a high-resolution emission inventory. Then emission fluxes were mapped on surfaces emitting source-specific species. Simulations were run independently over the defined micro-environments allowing the modeling of sub grid-scale concentration variability. Sub grid scale concentrations were therefore combined with demographic and human activity data to provide exposure estimates. The spatial distribution of human exposure was parameterized through a Monte-Carlo model. The new information concerning exposure variability was added to an existing epidemiological model to study relative health risks. A log-linear Poisson regression model was used for this purpose. The principal outcome of the investigation was that a new functionality was added to the regression model which allows the dissociation of the health risk associated with each pollutant (e.g. NO{sub 2} and PM{sub 2.5}). (author)

  7. La Suisse urbaine : entre ubiquité et absence.

    Directory of Open Access Journals (Sweden)

    Joëlle Salomon Cavin

    2004-09-01

    Full Text Available Le regard porté sur le territoire suisse est aujourd'hui loin d'être univoque. D'un côté, l'image d'une Suisse urbaine diffusée par des chercheurs, des associations qui militent en faveur des villes et par les offices fédéraux de statistique et d’aménagement du territoire. De nouvelles données et analyses sur le fait urbain ont permis le renouvellement de l’image de la ville en Suisse surtout considérées jusque-là pour leur impact négatif sur le territoire. Les villes sont devenues parties intégrantes de la politique de la Confédération au travers du concept du Réseau de villes suisses puis dans le cadre de la politique fédérale des agglomérations. Deux visions extrêmes de la Suisse urbaine s’opposent actuellement : l’une est une projection de la Suisse comme métropole, un territoire urbain multipolaire où les villes sont étroitement interconnectées, l’autre insiste sur l’importance de l’agglomération zurichoise comme seule réelle métropole de la Suisse. D’un autre côté, toutes ces interprétations de la Suisse urbaine cohabitent avec des représentations bien moins urbaines du territoire. La perception subjective de l’urbanisation par de jeunes recrues de même que leur désir en matière de logement reflètent l’image d’une Suisse considérée mais également désirée comme un pays encore très marqué par le rural. L’importance physique de la Nature, des lacs, des forets, des montagnes et des champs participe certainement de cette image peu urbaine du pays. Encore actuellement, des villes, à l’exemple de Schwyz, peuvent avoir conservé un aspect très villageois. Enfin, la stabilité des institutions politiques entretient également ce déni urbain. Ces deux visions contradictoires du territoire suisse, de même que les dissensions chez les tentants de la Suisse urbaine, permettent en conclusion de discuter la pertinence actuelle de l’utilisation de l’opposition ville

  8. Polarization Versus Agglomeration

    OpenAIRE

    Martinho, Vítor João Pereira Domingues

    2011-01-01

    The aim of this paper is to analyze the processes of polarization and agglomeration, to explain the mechanisms and causes of these phenomena in order to identify similarities and differences. As the main implication of this study should be noted that both process pretend to explain the concentration of economic activity and population in certain places, through cumulative phenomena, but with different perspectives, in other words, the polarization with a view of economic development and agglo...

  9. Agglomeration and innovation

    OpenAIRE

    Carlino, Gerald; Kerr,William Robert

    2014-01-01

    Draft chapter for the forthcoming Handbook of Regional and Urban Economics, Vols. 5A and 5B This paper reviews academic research on the connections between agglomeration and innovation. The authors first describe the conceptual distinctions between invention and innovation. They then discuss how these factors are frequently measured in the data and note some resulting empirical regularities. Innovative activity tends to be more concentrated than industrial activity, and the authors discuss im...

  10. Selective oil agglomeration of lignite

    Energy Technology Data Exchange (ETDEWEB)

    Halime Abakay Temel; Volkan Bozkurt; Arun Kumar Majumder [Dicle University, Diyarbakir (Turkey). Department of Mining Engineering

    2009-01-15

    In this study, desulfurization and deashing of Adiyaman-Glbai lignite by the agglomeration method were studied. For this purpose, three groups of agglomeration experiments were made. The effects of solid concentration, bridging liquid type and dosage, pH, and screen size on the agglomeration after desliming were investigated in the first group of experiments. The effects of lake water and sea water (the Mediterranean Sea water, the Aegean Sea water, and the Black Sea water) on the agglomeration were investigated in the second group of experiments. The effects of different salts (NaCl, MgCl{sub 2}, and FeCl{sub 3}) on the agglomeration were investigated in the third group of experiments. Agglomeration results showed that the usage of sea waters and soda lake water in the agglomeration medium had a positive effect on the reduction of total sulfur content of agglomerates. In addition, the usage of NaCl, MgCl{sub 2}, and FeCl{sub 3} in the agglomeration medium had a positive effect on the ash content reduction of the agglomerates. 27 refs., 10 figs., 6 tabs.

  11. L'Agriculture urbaine prend racine

    International Development Research Centre (IDRC) Digital Library (Canada)

    CRDI

    agriculteurs urbains que les anciennes attitudes se sont transformées face aux réalités nouvelles. Cette étude de cas a été rédigée par Kevin Conway de la. Division des communications du CRDI. Renseignements. Associate Professor George Nasinyama. Department of Veterinary Public Health and. Preventive Medicine.

  12. INTERMODALITE ET DEVELOPPEMENT URBAIN DANS L ...

    African Journals Online (AJOL)

    Administrateur

    énergie et moins polluants, moins consommateurs d'espaces également, par contre beaucoup plus .... telles que l'installation dans le pays de gros concessionnaires automobiles, le crédit à la consommation et les ... toutes les énergies au profit d'un développement urbain de l'agglomération qui soit plus respectueux de ...

  13. Réduire la violence urbaine : Pourquoi certains hommes choisissent ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Réduire la violence urbaine : Pourquoi certains hommes choisissent la violence? 25 juin 2015. Image. Les chercheurs examinent la façon dont les normes relatives aux genres dans les centres urbains influent sur les schémas de violence chez les hommes. Alice Taylor et Tatiana Moura. Qu'est-ce qui fait qu'un homme ...

  14. Spherical agglomeration of acetylsalicylic acid

    Directory of Open Access Journals (Sweden)

    Polowczyk Izabela

    2016-01-01

    Full Text Available In this paper spherical agglomeration of acetylsalicylic acid was described. In the first step, the system of good and poor solvents as well as bridging liquid was selected. As a result of a preliminary study, ethyl alcohol, water and carbon tetrachloride were used as the good solvent, poor one, and bridging liquid, respectively. Then, the amount of acetylsalicylic acid and the ratio of the solvents as well as the volume of the bridging liquid were examined. In the last step, the agglomeration conditions, such as mixing intensity and time, were investigated. The spherical agglomerates obtained under optimum conditions could be subjected to a tableting process afterwards.

  15. Do governments tax agglomeration rents?

    OpenAIRE

    Koh, Hyun-Ju; Riedel, Nadine

    2010-01-01

    Using the German local business tax as a testing ground, we empirically investigate the impact of firm agglomeration on municipal tax setting behavior. The analysis exploits a rich data source on the population of German firms to construct detailed measures for the communities’ agglomeration characteristics. The findings indicate that urbanization and localization economies exert a positive impact on the jurisdictional tax rate choice which confirms predictions of the theoretical New Econom...

  16. Microbial effects on colloidal agglomeration

    Energy Technology Data Exchange (ETDEWEB)

    Hersman, L.

    1995-11-01

    Colloidal particles are known to enhance the transport of radioactive metals through soil and rock systems. This study was performed to determine if a soil microorganism, isolated from the surface samples collected at Yucca Mountain, NV, could affect the colloidal properties of day particles. The agglomeration of a Wyoming bentonite clay in a sterile uninoculated microbial growth medium was compared to the agglomeration in the medium inoculated with a Pseudomonas sp. In a second experiment, microorganisms were cultured in the succinate medium for 50 h and removed by centrifugation. The agglomeration of the clay in this spent was compared to sterile uninoculated medium. In both experiments, the agglomeration of the clay was greater than that of the sterile, uninoculated control. Based on these results, which indicate that this microorganism enhanced the agglomeration of the bentonite clay, it is possible to say that in the presence of microorganisms colloidal movement through a rock matrix could be reduced because of an overall increase in the size of colloidal particle agglomerates. 32 refs.

  17. Nécessaire de sociolinguistique urbaine.

    Directory of Open Access Journals (Sweden)

    Yveline Lévy-Piarroux

    2004-11-01

    Full Text Available Deux volumes rassemblent les contributions de 17 chercheurs, essentiellement originaires de pays francophones (France, Belgique, Suisse, Canada, sous la direction de Thierry Bulot (Université de Rennes 2, qui introduit l’ensemble avec Cécile Bauvois (Université de Mont-Hainaut. Ces deux auteurs posent une question liminaire : peut-on distinguer une sociolinguistique urbaine d’une qui ne le serait pas ? Ou encore, peut-on distinguer entre une sociolinguistique dont les études sont ...

  18. Ambiances urbaines, écologie sensible

    OpenAIRE

    Thibaud, Jean-Paul

    2013-01-01

    International audience; L’environnement sensoriel des espaces habités, participant au bien-être des habitants, est l’objet d’une attention croissante tant des concepteurs de l’urbain que des chercheurs. Les nombreux travaux s’intéressant à l’écologie des villes en termes sonores, lumineux, thermiques, olfactifs... conduisent au développement d’approches qui vont de la notion de gêne à celle de confort, de la notion de paysage à celle d’ambiance. En faisant appel à une démarche d’ordre socio-e...

  19. Urban Planning Problems of Agglomerations

    Science.gov (United States)

    Olenkov, V. D.; Tazeev, N. T.

    2017-11-01

    The article explores the state of the air basin of the Chelyabinsk agglomeration and gives the examples of solutions for the pollution problems from the point of view of city planning. The main features and structure of the modern urban agglomerations are considered, the methods for determining their boundaries are studied and the main problems are identified. The study of the boundaries and territorial structure of the Chelyabinsk urban agglomeration is conducted, and a general description of the territory is given. The data on the change in the volume of pollutant emissions into the atmosphere and the index of atmospheric pollution for the period 2003-2015 are given basing on the annual comprehensive reports regarding the state of the environment. The review of the world experience of city-planning actions on the decision of ecological problems is carried out. The most suitable ways for the ecological problems solving in the Chelyabinsk agglomeration are considered. The authors give recommendations for the ecological situation improving in the territory of the Chelyabinsk agglomeration.

  20. Agglomeration Economies in Classical Music

    DEFF Research Database (Denmark)

    Borowiecki, Karol Jan

    2015-01-01

    This study investigates agglomeration effects for classical music production in a wide range of cities for a global sample of composers born between 1750 and 1899. Theory suggests a trade-off between agglomeration economies (peer effects) and diseconomies (peer crowding). I test this hypothesis...... using historical data on composers and employ a unique instrumental variable – a measure of birth centrality, calculated as the average distance between a composer’s birthplace and the birthplace of his peers. I find a strong causal impact of peer group size on the number of important compositions...

  1. Interaction entre zones urbaines et rurales et changements ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Ce projet vise à réduire la vulnérabilité des systèmes ruraux-urbains du Nigeria face aux changements climatiques en diffusant les résultats du projet pilote mené ... la migration rurale-urbaine et la dégradation de l'environnement qui en découle et rend les collectivités plus vulnérables face aux changements climatiques.

  2. The Role of Entropy in Nanoparticle Agglomeration.

    Science.gov (United States)

    Kätelhön, Enno; Sokolov, Stanislav V; Bartlett, Thomas R; Compton, Richard G

    2017-01-04

    Agglomeration processes in non-interacting particle systems can be understood from a thermodynamic point of view. If the enthalpy of agglomeration is negligible, the distribution of agglomeration states adopts the state of highest entropy. Herein, we provide the exact analytical solution to the mole fractions of agglomerates comprising i monomers, xi =2-i . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. LBM simulations on agglomerate transport and deposition

    Science.gov (United States)

    Dietzel, Mathias; Sommerfeld, Martin

    2010-03-01

    Agglomerated particles appear in various technical applications of the process industry in form of products, waste or contamination. Desired or undesired, these complex-structured particles need to be handled, involving transportation and separation processes, agglomerate growth and breakup as well as stabilization techniques. Both, fundamental research and industry have a strong demand of knowledge about agglomerate behavior. Numerical simulations are capable to provide an addition or even substitution of experimental data if accessibility is limited or too expensive. In this work, the Lattice Boltzmann Method (LBM) is used to perform high resolution simulations of agglomerates to investigate agglomerate transport and deposition depending on flow conditions and agglomerate structure. This paper presents an approach to generate and characterize three-dimensional agglomerates and to predict the flow around these aggregated structures using a 3D multi-scale LBM. The considered agglomerates are composed of spherical primary particles which are connected to each other by rigid joints. The characterization of the agglomerates is done using common equivalent diameters as well as the fractal dimension and the convex hull. Simulating the flow field around the agglomerates leads to the forces and torques acting on the aggregates. From that the drag, lift and torque coefficients can be determined and their dependencies on agglomerate structure, orientation and flow conditions can be estimated. The overall aim is modeling and simulating transport and deposition processes of agglomerated particles.

  4. Coal beneficiation by gas agglomeration

    Science.gov (United States)

    Wheelock, Thomas D.; Meiyu, Shen

    2003-10-14

    Coal beneficiation is achieved by suspending coal fines in a colloidal suspension of microscopic gas bubbles in water under atmospheric conditions to form small agglomerates of the fines adhered by the gas bubbles. The agglomerates are separated, recovered and resuspended in water. Thereafter, the pressure on the suspension is increased above atmospheric to deagglomerate, since the gas bubbles are then re-dissolved in the water. During the deagglomeration step, the mineral matter is dispersed, and when the pressure is released, the coal portion of the deagglomerated gas-saturated water mixture reagglomerates, with the small bubbles now coming out of the solution. The reagglomerate can then be separated to provide purified coal fines without the mineral matter.

  5. Microstickies agglomeration by electric field.

    Science.gov (United States)

    Du, Xiaotang Tony; Hsieh, Jeffery S

    2016-01-01

    Microstickies deposits on both paper machine and paper products when it agglomerates under step change in ionic strength, pH, temperature and chemical additives. These stickies increase the down time of the paper mill and decrease the quality of paper. The key property of microstickies is its smaller size, which leads to low removal efficiency and difficulties in measurement. Thus the increase of microstickies size help improve both removal efficiency and reduce measurement difficulty. In this paper, a new agglomeration technology based on electric field was investigated. The electric treatment could also increase the size of stickies particles by around 100 times. The synergetic effect between electric field treatment and detacky chemicals/dispersants, including polyvinyl alcohol, poly(diallylmethylammonium chloride) and lignosulfonate, was also studied.

  6. Environmental problems of Moscow agglomeration

    Directory of Open Access Journals (Sweden)

    V. P. Bondarev

    2014-01-01

    Full Text Available The work is devoted to the social consequences of the problem of interaction between society and the environment within the Moscow metropolitan area. There are two major blocks of the problem: the socio-ecological and environmental demographic. We consider the model of Moscow agglomeration due to the expansion of the territory of Moscow, as well as with the modern trends of expansion in the Moscow metropolitan area and the region as a whole. Showing solutions environmental problems.

  7. Evaluation of sanitary impact of urban air pollution. Methodological guide.; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Guide methodologique

    Energy Technology Data Exchange (ETDEWEB)

    Glorennec, Ph.; Nourry, L [Cellule Inter-Regionale d' Epidemiologie (France); Quenel, Ph. [Institut National de Veille Sanitaire, 94 - Saint Maurice (France)] [and others

    1999-07-01

    The institute of sanitary watch has setting up an epidemiological surveillance plan in nine french towns in order to quantify and to keep a close eye to the relations existing between the urban air pollution and the populations health.The method is detailed with its advantages and its limits. (N.C.)

  8. Les sites web d’information urbaine au Maroc

    OpenAIRE

    Béatrice Allain-El Mansouri

    2016-01-01

    Le Maroc, en tant que pays émergent, est confronté à des degrés divers aux problèmes urbains que connaissent de façon récurrente les pays du Sud, en particulier ceux du continent africain : pauvreté, persistance des bidonvilles et prolifération de l’habitat insalubre et non réglementaire, engorgement des transports urbains, défaillance des services de base (eau potable, électricité et assainissement liquide) et dégradation de l’environnement (pollution). Dans le cadre des Objectifs du Milléna...

  9. L’eau urbaine ou le pouvoir de renaturer

    Directory of Open Access Journals (Sweden)

    Franck Scherrer

    2004-12-01

    Full Text Available L’eau dans la ville (fleuve, lac, mer.. est au centre de nombreuses politiques urbaines (renouvellement urbain, waterfront, protection écologique, loisirs, culture, espaces publics…. Celles-ci s’exercent sur les mêmes espaces au nom de la renaturation. Mais cette référence commune cache des systèmes de valeurs et des coalitions d’acteurs différents qui sont en compétition pour s’arroger ce pouvoir de renaturer la ville.

  10. Understanding and preventing agglomeration during filter drying

    OpenAIRE

    HONG LEE LIM

    2017-01-01

    The agitated filter dryer is one of the most popular dryers used in the production of active pharmaceutical ingredients. However, the advantages of a filter dryer are often offset by the susceptibility of powder to undergo undesired agglomeration during the process. Consequently, the formation of agglomerates may lead to extended drying time, variation in physical properties and product degradation. This thesis addresses the recurring agglomeration issues faced in the agitated drying of powde...

  11. Analyzing Agricultural Agglomeration in China

    Directory of Open Access Journals (Sweden)

    Erling Li

    2017-02-01

    Full Text Available There has been little scholarly research on Chinese agriculture’s geographic pattern of agglomeration and its evolutionary mechanisms, which are essential to sustainable development in China. By calculating the barycenter coordinates, the Gini coefficient, spatial autocorrelation and specialization indices for 11 crops during 1981–2012, we analyze the evolutionary pattern and mechanisms of agricultural agglomeration. We argue that the degree of spatial concentration of Chinese planting has been gradually increasing and that regional specialization and diversification have progressively been strengthened. Furthermore, Chinese crop production is moving from the eastern provinces to the central and western provinces. This is in contrast to Chinese manufacturing growth which has continued to be concentrated in the coastal and southeastern regions. In Northeast China, the Sanjiang and Songnen plains have become agricultural clustering regions, and the earlier domination of aquaculture and rice production in Southeast China has gradually decreased. In summary, this paper provides a political economy framework for understanding the regionalization of Chinese agriculture, focusing on the interaction among the objectives, decisionmaking behavior, path dependencies and spatial effects.

  12. Comportement des polluants des eaux pluviales urbaines en ...

    African Journals Online (AJOL)

    VIS. Thèse de. Doctorat en sciences et techniques de l'environnement. Université d'Annaba, Algérie. 167p. [11] Bressy A., 2010. Flux de micropolluants dans les eaux de ruissellement urbaines. Effets de différents modes de gestion des eaux ...

  13. un_focus - Cultiver de meilleures villes : Agriculture urbaine et ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    totalité de la croissance démographique se produira dans les villes des pays en développement. Si la tendance actuelle se maintient, 60 % de la population de la planète vivra en milieu urbain d'ici à 2030. Plus les villes grossissent, plus leur ...

  14. On the mechanism of agglomeration in suspension

    Directory of Open Access Journals (Sweden)

    Maryam Maghsoodi

    2012-06-01

    Full Text Available Purpose: Agglomeration in suspension is a size enlargement method that facilitates operation of solid processing and preserves the solubilization properties of fine particles. A small quantity of binder liquid is added into a suspension of microparticles, directly in the stirred vessel where the precipitation or crystallization took place. This study deals with the evaluation of the effect of agitation time before and after addition of binder liquid on agglomerates properties in order to give some insights into the mechanism of the formation of the agglomerates. Methods: Carbamazepine is used as a model drug and isopropyl acetate is used as binder liquid. The agglomerates characterization includes the particle size, morphology and density. Results: The results showed that, by increasing the agitation time before addition of binder liquid, smaller agglomerates with less density and irregular forms composed of larger crystals were obtained. However, with increasing agitation time after addition of binder liquid the agglomerates size and density increases and morphology improves. Indeed, by continuing agitation along the course of agglomeration the properties of the particles change gradually but substantially. Conclusion: With optimized agitation time before and after addition of binder liquid, spherical and dense agglomerates can be obtained.

  15. Low-rank coal oil agglomeration

    Science.gov (United States)

    Knudson, C.L.; Timpe, R.C.

    1991-07-16

    A low-rank coal oil agglomeration process is described. High mineral content, a high ash content subbituminous coals are effectively agglomerated with a bridging oil which is partially water soluble and capable of entering the pore structure, and is usually coal-derived.

  16. Effect of agglomeration during coprecipitation: Delayed ...

    Indian Academy of Sciences (India)

    Precipitation of magnesium aluminate hydrate with faster addition of ammonia at desired pH causes agglomeration. Agglomerated powder, without any further treatment, on calcination forms intermediate compounds at low temperatures (≤ 900°C). The intermediate compounds on further heat treatment (≥ 1000°C) ...

  17. Engineering development of selective agglomeration. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1993-04-01

    This report presents the findings of the project entitled ``Engineering Development of Selective Agglomeration.`` The purpose is to develop selective agglomeration technology to a commercially acceptable level by 1993. Engineering development included bench-scale process development, component development adaptation or modification of existing unit operations, proof-of-concept (POC) module design, fabrication, testing, data evaluation, and conceptual design of a commercial facility. The information obtained during POC operation resulted in a technical and economic design base sufficient to support construction and operation of a commercial plant. Throughout this project performance targets for the engineering development of selective agglomeration process were to achieve 85% or greater Btu recovery at 85% or greater pyritic sulfur rejection (PSR). Additional objectives included producing a final clean-coal product with an ash content of 6% or less which is suitable for conventional coal handling systems. The selective agglomeration process, as applied to coal cleaning, is based on differences in the surface chemistry of coal and its associated impurities. Coal particles are hydrophobic (i.e., repel water) while the majority of its impurities are hydrophilic (i.e., stabilized in water). During selective agglomeration, a liquid (the agglomerant) that is immiscible with water is introduced into a coal-water slurry and agitated to disperse it in the slurry, thereby allowing it to come into contact with all particles in the slurry. The coal particles, due to their hydrophobic nature, are attracted to the agglomerant phase. The hydrophilic mineral impurities remain in the water phase. Continued agitation of the agglomerant-coated coal particles causes them to coalesce to form agglomerates. Once the agglomerates are formed, they are separated from the mineral matter-bearing aqueous phase by subsequent processing steps.

  18. Particle agglomeration and properties of nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Yang Yijun; Oztekin, Alparslan, E-mail: alo2@lehigh.edu; Neti, Sudhakar [Lehigh University, Department of Mechanical Engineering and Mechanics (United States); Mohapatra, Satish [Dynalene Inc. (United States)

    2012-05-15

    The present study demonstrates the importance of actual agglomerated particle size in the nanofluid and its effect on the fluid properties. The current work deals with 5 to 100 nm nanoparticles dispersed in fluids that resulted in 200 to 800 nm agglomerates. Particle size distributions for a range of nanofluids are measured by dynamic light scattering (DLS). Wet scanning electron microscopy method is used to visualize agglomerated particles in the dispersed state and to confirm particle size measurements by DLS. Our results show that a combination of base fluid chemistry and nanoparticle type is very important to create stable nanofluids. Several nanofluids resulted in stable state without any stabilizers, but in the long term had agglomerations of 250 % over a 2 month period. The effects of agglomeration on the thermal and rheological properties are presented for several types of nanoparticle and base fluid chemistries. Despite using nanodiamond particles with high thermal conductivity and a very sensitive laser flash thermal conductivity measurement technique, no anomalous increases of thermal conductivity was measured. The thermal conductivity increases of nanofluid with the particle concentration are as those predicted by Maxwell and Bruggeman models. The level of agglomeration of nanoparticles hardly influenced the thermal conductivity of the nanofluid. The viscosity of nanofluids increased strongly as the concentration of particle is increased; it displays shear thinning and is a strong function of the level of agglomeration. The viscosity increase is significantly above of that predicted by the Einstein model even for very small concentration of nanoparticles.

  19. Positive impact of agglomeration in nanocomposite conductivity

    Science.gov (United States)

    Tarlton, Taylor; Sullivan, Ethan; Derosa, Pedro

    CNTs are embedded in an insulating matrix to form composites to improve its mechanical, thermal and electrical properties. However, CNTs tend to clump together forming agglomerates and thus Experimental studies on CNT composites normally describe significant effort in dispersing CNT for a more effective performance. Although the main concern is on the impact agglomeration has on mechanical strength, it is accepted that agglomeration will also negatively affect conductivity. In this workg computer simulations are used to study this effect in detail and it is found that some level of agglomeration actually improves conductivity by a better use of the available volume. Agglomerates leave voids in the sample in favor of other areas where the CNT-CNT distance is smaller than it would be if their distribution were uniform thus improving conductivity. More uniform samples have more conduction paths, but CNT-CNT distance is in average larger leading to a lower mobility. The opposite happen when some agglomeration is present and thus there is a tradeoff that above, but near, percolation leads to higher conductivity in the case where some agglomeration is present. At higher concentrations, the effect of mobility seems to be larger as there are enough conduction paths already available. This work is supported by Air Force Research Collaboration Program; contract FA8650-13-C-5800 from the Air Force Research Laboratory,.

  20. Modeling of particle agglomeration in nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Krishna, K. Hari; Neti, S.; Oztekin, A. [Department of Mechanical Engineering and Mechanics, Lehigh University, 19W Memorial Dr, Bethlehem, Pennsylvania 18015 (United States); Mohapatra, S. [Dynalene Inc., 5250W Coplay Rd, Whitehall, Pennsylvania 18052 (United States)

    2015-03-07

    Agglomeration strongly influences the stability or shelf life of nanofluid. The present computational and experimental study investigates the rate of agglomeration quantitatively. Agglomeration in nanofluids is attributed to the net effect of various inter-particle interaction forces. For the nanofluid considered here, a net inter-particle force depends on the particle size, volume fraction, pH, and electrolyte concentration. A solution of the discretized and coupled population balance equations can yield particle sizes as a function of time. Nanofluid prepared here consists of alumina nanoparticles with the average particle size of 150 nm dispersed in de-ionized water. As the pH of the colloid was moved towards the isoelectric point of alumina nanofluids, the rate of increase of average particle size increased with time due to lower net positive charge on particles. The rate at which the average particle size is increased is predicted and measured for different electrolyte concentration and volume fraction. The higher rate of agglomeration is attributed to the decrease in the electrostatic double layer repulsion forces. The rate of agglomeration decreases due to increase in the size of nano-particle clusters thus approaching zero rate of agglomeration when all the clusters are nearly uniform in size. Predicted rates of agglomeration agree adequate enough with the measured values; validating the mathematical model and numerical approach is employed.

  1. Modeling of particle agglomeration in nanofluids

    Science.gov (United States)

    Krishna, K. Hari; Neti, S.; Oztekin, A.; Mohapatra, S.

    2015-03-01

    Agglomeration strongly influences the stability or shelf life of nanofluid. The present computational and experimental study investigates the rate of agglomeration quantitatively. Agglomeration in nanofluids is attributed to the net effect of various inter-particle interaction forces. For the nanofluid considered here, a net inter-particle force depends on the particle size, volume fraction, pH, and electrolyte concentration. A solution of the discretized and coupled population balance equations can yield particle sizes as a function of time. Nanofluid prepared here consists of alumina nanoparticles with the average particle size of 150 nm dispersed in de-ionized water. As the pH of the colloid was moved towards the isoelectric point of alumina nanofluids, the rate of increase of average particle size increased with time due to lower net positive charge on particles. The rate at which the average particle size is increased is predicted and measured for different electrolyte concentration and volume fraction. The higher rate of agglomeration is attributed to the decrease in the electrostatic double layer repulsion forces. The rate of agglomeration decreases due to increase in the size of nano-particle clusters thus approaching zero rate of agglomeration when all the clusters are nearly uniform in size. Predicted rates of agglomeration agree adequate enough with the measured values; validating the mathematical model and numerical approach is employed.

  2. Les métamorphoses du marketing urbain.

    Directory of Open Access Journals (Sweden)

    Marc Dumont

    2006-02-01

    Full Text Available Si le marketing urbain n’est pas récent, il est important d’interroger les effets qu’a pu ou non avoir l’irruption du numérique sur ce phénomène, tant au niveau de ses modalités, de ses modes de structurations, que des problématiques de la production de la ville dans lesquelles il s’inscrit. L’intérêt d’évoquer cette question à partir d’un site internet développé exclusivement pour un quartier tertiaire émargeant à deux projets urbains importants, Euronantes.fr, ...

  3. Les sites web d’information urbaine au Maroc

    Directory of Open Access Journals (Sweden)

    Béatrice Allain-El Mansouri

    2016-02-01

    Full Text Available Le Maroc, en tant que pays émergent, est confronté à des degrés divers aux problèmes urbains que connaissent de façon récurrente les pays du Sud, en particulier ceux du continent africain : pauvreté, persistance des bidonvilles et prolifération de l’habitat insalubre et non réglementaire, engorgement des transports urbains, défaillance des services de base (eau potable, électricité et assainissement liquide et dégradation de l’environnement (pollution. Dans le cadre des Objectifs du Milléna...

  4. Grafmeyer Yves, Authier Jean-Yves, Sociologie urbaine

    Directory of Open Access Journals (Sweden)

    Anaïs Van Sull

    2011-02-01

    Full Text Available Yves Grafmeyer et Jean-Yves Authier ont consacré la plupart de leurs travaux de recherche aux questions de l’espace urbain et de la socialisation qui y prend place. L’ouvrage qu’ils proposent, enrichi et actualisé par rapport à la première édition, aborde les différents objets, méthodes et problématiques qui peuvent être insérés dans le champ de la sociologie urbaine. S’ils reconnaissent une large part d’arbitraire dans les concepts et courants retenus, on ne peut que se réjouir des nouvelles...

  5. Malaise dans la pensée urbaine.

    Directory of Open Access Journals (Sweden)

    Jacques Lévy

    2004-09-01

    Full Text Available Le numéro de mars-avril 2004 de la revue Esprit présente un dossier consistant (272 pages sur la ville. L’idée de se représenter le monde urbain de France et d’ailleurs en trois strates, trois auréoles et trois vitesses, correspond à une perception spontanée que ne démentent pas les études savantes : les centres, les banlieues populaires et le périurbain constituent bien une tripartition des espaces urbains. Ce constat sert de trame générale au numéro. Mais ici s’arrête ...

  6. TIC et microentreprises en milieu urbain : optimisation des ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    TIC et microentreprises en milieu urbain : optimisation des possibilités de développement économique. La population des villes croît à un rythme plus rapide que l'ensemble de la population mondiale, surtout dans les pays en développement. Les technologies de l'information et de la communication (TIC), notamment la ...

  7. Le secteur prive des transports urbains de voyageurs, quelles ...

    African Journals Online (AJOL)

    C'est dans un climat de crise économique où les pouvoirs publics perdent la capacité de financement et de développement des transports en commun et devant la ... une régulation du marché par une concurrence encadrée par le biais des appels d'offre pour la concession des services de transport urbain de voyageurs.

  8. Pollution des eaux à usages domestiques dans les milieux urbains ...

    African Journals Online (AJOL)

    Cette synthèse bibliographique sur l'état de la qualité des eaux à usages domestiques en milieux urbains de quelques pays africains a été faite à partir de la collecte des données issues des rapports d'activités de mémoires, de thèses, des publications et des ouvrages. Elle révèle que les différentes sources.

  9. Pollution des eaux à usages domestiques dans les milieux urbains ...

    African Journals Online (AJOL)

    Botta A, Bellon L. 2004. Pollution chimique de l'eau et santé humaine. Service de médecine et santé au travail. Laboratoire de biolgénotoxicologie et mutagenèse environnementale (EA 1784, IFR PMSE. 112), p. 23. Boubakar Hassane A. 2010. Aquifères superficiels et profonds et pollution urbaine en Afrique : Cas de la.

  10. Pollution des eaux à usages domestiques dans les milieux urbains ...

    African Journals Online (AJOL)

    Cette synthèse bibliographique sur l'état de la qualité des eaux à usages domestiques en milieux urbains de quelques pays africains a été faite à partir de la collecte des données issues des rapports d'activités de mémoires, de thèses, des publications et des ouvrages. Elle révèle que les différentes sources ...

  11. Theoretical studies on aerosol agglomeration processes

    Energy Technology Data Exchange (ETDEWEB)

    Lehtinen, K.E.J. [VTT Energy, Espoo (Finland). Energy Use

    1997-12-31

    In this thesis, theoretical modeling of certain aerosol systems has been presented. At first, the aerosol general dynamic equation is introduced, along with a discretization routine for its numerical solution. Of the various possible phenomena affecting aerosol behaviour, this work is mostly focused on aerosol agglomeration. The fundamentals of aerosol agglomeration theory are thus briefly reviewed. The two practical applications of agglomeration studied in this thesis are flue gas cleaning using an electrical agglomerator and nanomaterial synthesis with a free jet reactor. In an electrical agglomerator the aerosol particles are charged and brought into an alternating electric field. The aim is to remove submicron particles from flue gases by collisions with larger particles before conventional gas cleaning devices that have a clear penetration window in the problematic 0.1-1{mu}m size range. A mathematical model was constructed to find out the effects of the different system parameters on the agglomerator`s performance. A crucial part of this task was finding out the collision efficiencies of particles of varying size and charge. The original idea was to use unipolar charging of the particles, and a laboratory scale apparatus was constructed for this purpose. Both theory and experiments clearly show that significant removal of submicron particles can not be achieved by such an arrangement. The theoretical analysis further shows that if the submicron particles and the large collector particles were charged with opposite polarity, significant removal of the submicron particles could be obtained. The second application of agglomeration considered in this thesis is predicting/controlling nanoparticle size in the gas-to-particle aerosol route to material synthesis. In a typical material reactor, a precursor vapor reacts to form molecules of the desired material. In a cooling environment, a particulate phase forms, the dynamics of which are determined by the rates of

  12. Faire campagne en ville : L'agriculture urbaine en Afrique de l'Est ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Faire campagne en ville : L'agriculture urbaine en Afrique de l'Est. Couverture du livre Faire campagne en ville : L'agriculture urbaine en Afrique de l. Auteur(s) : Auxumite G. Egziabher, Diana Lee-Smith, Daniel G. Maxwell, Pyar Ali Memon, Luc Mougeot et Camillus J. Sawio. Maison(s) d'édition : CRDI. 1 janvier 1995.

  13. Protection de la communauté urbaine de Cotonou face aux ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Protection de la communauté urbaine de Cotonou face aux changements climatiques (Bénin). Ce projet vise à renforcer la capacité d'adaptation des populations de la communauté urbaine de Cotonou aux inondations. Il le fera en mettant en oeuvre un processus participatif de diagnostic, d'analyse et de planification de ...

  14. Le dilemme urbain : comment rendre les villes plus sûres | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Plus de la moitié de la population mondiale — quelque 3,4 milliards de personnes — habite aujourd'hui dans des milieux urbains. Bon nombre de villes en forte croissance connaissent aussi une hausse marquée de la violence. Cependant, on sait peu de choses sur les causes de la violence urbaine, plus particulièrement ...

  15. Recherche sur l'environnement alimentaire urbain obésogène, ses ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    environnement alimentaire. En Afrique du Sud, par exemple, les ménages en milieu urbain et périurbain (à proximité des régions urbaines), et de plus en plus ceux en milieu rural, ont recours de manière croissante à des aliments malsains et ...

  16. A dynamic analysis of the agglomeration and performance relationship

    OpenAIRE

    Marco-Lajara, Bartolomé; Claver Cortés, Enrique; Úbeda García, Mercedes; Zaragoza Sáez, Patrocinio del Carmen

    2016-01-01

    This study takes a dynamic approach to the study of the economies of agglomeration in the tourist districts of the Spanish Mediterranean coast. Results suggest that company growth has a U-shaped relationship with the degree of agglomeration, which means that first levels of agglomeration profits decrease until they reach a certain point of agglomeration, from which business growth begins to increase. This process means that hotels in tourist districts with a high degree of agglomeration are n...

  17. Experimental and theoretical study of the atmospheric boundary layer over the paris area; Etude experimentale et theorique de la couche limite atmospherique en agglomeration parisienne

    Energy Technology Data Exchange (ETDEWEB)

    Menut, L

    1997-12-15

    This thesis studied the urban boundary layer dynamic behaviour over the Paris area by comparing urban (Paris) and suburban (Palaiseau) dynamic data such as lidars, sodars, sonic anemometers. All the data were obtained during the ECLAP experiment, specifically performed to characterize the differences between a city and its near environment. (author)

  18. Cohesion and agglomeration of wet powders

    Science.gov (United States)

    Raux, Pascal S.; Biance, Anne-Laure

    2018-01-01

    Wet high-shear granulation consists in vigorously mixing grains and a liquid binder to create agglomerates of various sizes. The process results from a balance between cohesion of the wet granular agglomerates and fragmentation due to the high mixing. By performing a simple test with glass beads and various liquids, we first focus on the static cohesion of wet granular media. Contrary to previous works, we extend the study to larger values of the liquid fraction w . After the well-documented plateau, the cohesive strength increases again with w , a behavior we capture by a simple model. We then focus on the dynamical cohesion of the media and we design an agglomeration process that consists in vibrating a bead/liquid mixture at a large amplitude. The vibrations induce not only the fluidization of the wet granular material but also the formation of aggregates. As expected, their size is affected by the liquid content, the frequency, and the amplitude of the vibrations, similarly to high-shear granulation data. However, the number of beads in an agglomerate does not depend on the bead size, showing a self-similar mechanism of agglomeration. The role of the static cohesion strength in this dynamical process remains therefore ambiguous.

  19. Caracterisation environnementale des emissions atmospheriques d'une source fixe et creation d'un outil de gestion dynamique =

    Science.gov (United States)

    Fournier, Marie-Claude

    Une caracterisation des emissions atmospheriques provenant des sources fixes en operation, alimentees au gaz et a l'huile legere, a ete conduite aux installations visees des sites no.1 et no.2. La caracterisation et les calculs theoriques des emissions atmospheriques aux installations des sites no.1 et no.2 presentent des resultats qui sont en dessous des valeurs reglementaires pour des conditions d'operation normales en periode hivernale et par consequent, a de plus fortes demandes energetiques. Ainsi, pour une demande energetique plus basse, le taux de contaminants dans les emissions atmospheriques pourrait egalement etre en dessous des reglementations municipales et provinciales en vigueur. Dans la perspective d'une nouvelle reglementation provinciale, dont les termes sont discutes depuis 2005, il serait souhaitable que le proprietaire des infrastructures visees participe aux echanges avec le Ministere du Developpement Durable, de l'Environnement et des Parcs (MDDEP) du Quebec. En effet, meme si le principe de droit acquis permettrait d'eviter d'etre assujetti a la nouvelle reglementation, l'application de ce type de principe ne s'inscrit pas dans ceux d'un developpement durable. L'âge avance des installations etudiees implique la planification d'un entretien rigoureux afin d'assurer les conditions optimales de combustion en fonction du type de combustible. Des tests de combustion sur une base reguliere sont donc recommandes. Afin de supporter le processus de suivi et d'evaluation de la performance environnementale des sources fixes, un outil d'aide a la gestion de l'information environnementale a ete developpe. Dans ce contexte, la poursuite du developpement d'un outil d'aide a la gestion de l'information environnementale faciliterait non seulement le travail des personnes affectees aux inventaires annuels mais egalement le processus de communication entre les differents acteurs concernes tant intra- qu'inter-etablissement. Cet outil serait egalement un bon

  20. Cultiver les alternatives: le jardin urbain en question

    OpenAIRE

    Poupon, Louis Bonaventure; Moroni, Isabelle

    2017-01-01

    Cette recherche décrit une aventure individuelle et collective, de citoyens impliqués dans la création d’un espace particulier, le jardin urbain. Un engagement dans l’action qui amène à questionner certaines conventions et expérimenter de nouvelles pratiques. Afin de mesurer la portée de ce projet, il a été nécessaire d’explorer et d’approfondir certaines notions : les mouvements sociaux, l’espace public, l’émancipation. C’est pourquoi ce travail de recherche a comme objectif d’identifier...

  1. Understanding Lateritic Ore Agglomeration Behaviour as a ...

    African Journals Online (AJOL)

    user

    To date, produc- ing of granules with desirable attributes poses a major geotechnical challenge to industry. In the present work, we investigate agglomeration behaviour of siliceous goethite Ni laterite ore and selected oxides and ... eration Behaviour as a Precursor to Enhanced Heap Leaching”, Ghana Mining Journal, pp.

  2. Moscow: capital - global city - agglo-meration

    Directory of Open Access Journals (Sweden)

    I. A. Vershinina

    2014-01-01

    Full Text Available The article discusses the specifics and peculiarities of Moscow as a multifunctional object with the functions of the capital, a global city and agglomeration. Analyzed stages in the development of its new features and main social problems that modern Moscow faced.

  3. Agriculture urbaine en Afrique de l'Ouest : Une contribution à la ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Cet ouvrage décrit la contribution précieuse de l'agriculture urbaine à la sécurité alimentaire et à l'assainissement des agglomérations urbaines d'Afrique centrale et d'Afrique de l'Ouest. Il présente également une stratégie destinée à établir un réseau consacré à l'agriculture en milieu urbain avec l'apport d'acteurs multiple ...

  4. Secteur TIC et refonte de la gouvernance urbaine

    Directory of Open Access Journals (Sweden)

    Divya Leducq

    2013-11-01

    Full Text Available En Inde, l’apparition de nouvelles formes de gouvernance territoriale est liée à la conjonction de deux processus : la mondialisation économique (part croissante du pays dans les échanges internationaux et les réformes politiques (décentralisation. Cet article examine la refonte de la gouvernance urbaine dans une grande ville indienne, Pune, dans l’État du Maharashtra. A la fois cause et conséquence de l’explosion de l’économie numérique, un certain nombre d’acteurs dont les associations patronales, développent des stratégies pour insérer davantage la « Reine du Deccan » dans le système de production globalisé. L’influence grandissante de certains groupes d’intérêts privés métamorphose la ville et redéfinit la distribution des rôles dans l’administration des affaires urbaines. La construction d’un nouvel espace technopolitain à Pune s’accomplit au détriment d’un développement durable et équitable.

  5. Quelles valeurs pour revaloriser les territoires urbains ?

    Directory of Open Access Journals (Sweden)

    Camille Tiano

    2010-05-01

    Full Text Available La notion de revalorisation territoriale est difficile à définir précisément puisqu’elle correspond à la fois à des valeurs chiffrables, qui permettent de dresser des palmarès socio-économiques, mais également à des valeurs intangibles liées aux représentations et aux expériences différenciées que les citadins ont des espaces urbains. De fait, les valeurs mises en avant par les différentes opérations urbaines sont très variables : des valeurs de rupture structurent l’action et l’image de l’opération Euralille, des valeurs méthodologiques sont à l’œuvre dans le projet Neptune à Dunkerque et des valeurs clichés et fluctuantes peinent à caractériser l’opération Euroméditerranée. Aussi hétérogènes soient-elles, les valeurs sont au cœur du processus opérationnel de revalorisation, en alimentant les conflits, en structurant les récits et en légitimant les figures politiques.

  6. Le patrimoine urbain en Asie centrale 

    Directory of Open Access Journals (Sweden)

    Guillemette Pincent

    2009-06-01

    Full Text Available Le « patrimoine urbain » est une expression utilisée en Europe occidentale depuis le début du XXe siècle. Quelle signification prend-il en Asie centrale ? Nous verrons que le patrimoine urbain y est un concept étatique qui répond à des impératifs économiques, politiques et non historiques. Il regroupe principalement des monuments utiles au pouvoir politique et se soucie peu de l’authenticité historique chère à l’Occident.The “urban heritage” is an expression used in Western Europe since the beginning of XXth century. What meaning does it take in Central Asia? We shall see that the urban heritage is a state concept, which answers to economic, political and not historic imperatives. It includes mainly monuments useful for the political power and cares few about the historic authenticity advocated by the West.

  7. Filtration behavior of silver nanoparticle agglomerates and effects of the agglomerate model in data analysis

    Energy Technology Data Exchange (ETDEWEB)

    Buha, Jelena, E-mail: jelena.buha@empa.ch [Empa, Analytical Chemistry (Switzerland); Fissan, Heinz [Institute of Energy and Environmental Technology e.V. (IUTA) (Germany); Wang, Jing, E-mail: jing.wang@ifu.baug.ethz.ch [Empa, Analytical Chemistry (Switzerland)

    2013-07-15

    In many data evaluation procedures for particle measuring devices and in filtration models, spherical particles are assumed. However, significant fractions of aerosol particles are agglomerates of small primary spheres. The morphology of particles in filtration processes may not be known a priori and if the filtration data are processed with wrong assumption, errors can be induced. In this work, we have quantified such errors for the case of open-structured agglomerates. Filtration efficiency tests with polydisperse silver nanoparticle agglomerates and their sintered spheres were performed. After the sintering process, particles with a compact structure with the shape close to a sphere are obtained, which are referred to as sintered spheres in the present study. The testing method involved generation of particulate forms, passing the particles through the testing section, and measurement of the particle number concentrations and size distributions before and after the filter. Measurements of the aerosols upstream and downstream of the filter were conducted using scanning mobility particle sizers (SMPS, TSI Inc.), which covered the rage from 10 to 480 nm. Particles were additionally characterized from the electron microscopic images and the average primary particle size was determined to be 16.8 nm. The number-size distribution curves were obtained and used for penetration calculation. The penetration was dependent on the particle size and morphology. Silver-sintered spheres were captured with a lower efficiency than agglomerates with the same mobility diameter because of the stronger interception effect for agglomerates. Data analysis of the number-size distribution for agglomerates was processed based on sphere assumption and using the model for open-structured agglomerates developed by Lall and Friedlander. The efficiencies based on total concentrations of number, surface and volume were affected when the agglomerate model was used. The effect was weakest for the

  8. Analysis of Urban Agglomeration and Its Meaning for Rural People.

    Science.gov (United States)

    Spiegelman, Robert G.

    Agglomeration--the clustering of people, businesses, or structures within an area--is investigated for two purposes: (1) defining the nature of agglomeration and erecting a suitable agglomeration theory, and (2) suggesting further research. These two objectives are seen as being vital to help improve the economic well-being of rural people by…

  9. Effect of temperature on wet agglomeration of crystals

    Directory of Open Access Journals (Sweden)

    Maryam Maghsoodi

    2014-05-01

    Full Text Available Objective(s:This study dealt with the wet agglomeration process in which a small quantity of binder liquid was added into a suspension of crystals, directly in the stirring vessel where the crystallization took place. The purpose of this investigation was evaluation of the effect of temperature on the agglomeration process in order to gain insight into the mechanism of the formation of the agglomerates. Materials and Methods: Carbamazepine was used as a model drug and water/ethanol and isopropyl acetate were used as crystallization system and binder liquid, respectively. The agglomeration of crystals was carried out at various temperatures and the agglomerates were characterized in terms of size, morphology, density and mechanical strength. Results: Evaluation of the agglomerates along the course of agglomeration shows that the properties of the particles change gradually but substantially. Higher temperature of the system during agglomeration process favors the formation of more regular agglomerates with mechanically stronger and denser structure; this can be explained by the promotion effect of temperature on the agglomeration process. Conclusion: With optimized wet agglomeration temperature, spherical, dense, and strong agglomerates can be obtained.

  10. Water migration mechanisms in amorphous powder material and related agglomeration

    NARCIS (Netherlands)

    Renzetti, S.; Voogt, J.A.; Oliver, L.; Meinders, M.B.J.

    2012-01-01

    The agglomeration phenomenon of amorphous particulate material is a major problem in the food industry. Currently, the glass transition temperature (Tg) is used as a fundamental parameter to describe and control agglomeration. Models are available that describe the kinetics of the agglomeration

  11. Systèmes de production et pratiques à risque en agriculture urbaine ...

    African Journals Online (AJOL)

    La question de l'impact de l'agriculture urbaine sur l'environnement revient, fréquemment, au coeur des débats dans la gestion des villes africaines, comme Yamoussoukro. Les inquiétudes liées à la préservation de l'environnement urbain, eu égard à l'usage de pesticides et à la qualité des eaux utilisées, constituent une ...

  12. Nature et acteurs de la violence urbaine en République ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    La nature et les acteurs de la violence urbaine en République démocratique du Congo. La République démocratique du Congo fait face à une violence et une criminalité urbaines grandissantes et en mutation continue dans un contexte de fragilité sur le plan des institutions et de la sécurité, d'urbanisation galopante, ...

  13. Agglomeration of mesoscopic particles in plasma

    Energy Technology Data Exchange (ETDEWEB)

    Annaratone, B M; Elskens, Y; Arnas, C [PIIM, Universite de Provence, Campus St. Jerome, case 321, F-13397 Marseille (France); Antonova, T; Thomas, H M; Morfill, G E [Max-Planck Institut fuer Extraterrestrische Physik, D-85741 Garching (Germany)], E-mail: bma@mpe.mpg.de

    2009-10-15

    We disclose the basic mechanism of agglomeration of nano-sized particles. While for weakly coupled, mono-dispersed particles the electrostatic agglomeration has always been found to be unlikely, in strongly coupled complex (dusty) plasmas the occupation of positive states for small particles is relevant, leading to electrostatic attraction between differently charged particles. The occupation of positively charged states is further enhanced by dispersed distribution of size. The smaller particles are trapped by the larger, the accretion of which gives a positive feedback on the probability of positively charged small grains and then further accretion. Experiments on growth of carbon particles from sputtered graphite in RF and dc Argon plasma confirm the general theoretical prediction when the energy of the ions corresponds to plasma boundaries.

  14. Quantifying Retail Agglomeration using Diverse Spatial Data.

    Science.gov (United States)

    Piovani, Duccio; Zachariadis, Vassilis; Batty, Michael

    2017-07-14

    Newly available data on the spatial distribution of retail activities in cities makes it possible to build models formalized at the level of the single retailer. Current models tackle consumer location choices at an aggregate level and the opportunity new data offers for modeling at the retail unit level lacks an appropriate theoretical framework. The model we present here helps to address these issues. Based on random utility theory, we have built it around the idea of quantifying the role of floor-space and agglomeration in retail location choice. We test this model on the inner area of Greater London. The results are consistent with a super linear scaling of a retailer's attractiveness with its floorspace, and with an agglomeration effect approximated as the total retail floorspace within a 300 m radius from each shop. Our model illustrates many of the issues involved in testing and validating urban simulation models involving spatial data and its aggregation to different spatial scales.

  15. Specialization and Agglomeration Patterns in Eastern Europe

    Directory of Open Access Journals (Sweden)

    Chapman, Sheila A.

    2013-04-01

    Full Text Available The paper investigates specialization and agglomeration trends in EU-27 NUTS2 regions over 1991-2011 by means of two versions of the relative Theil indicator that use employment data. The paper’s main focus is on Central and Eastern European Countries (CEECs regions. As a legacy of central planning, in the early ‘Nineties these regions presented significantly above-average specialization and agglomeration. The paper shows that over 1991-2011 these features change very little; moreover, while disproportions fall in the other EU members, they rise in CEECs, implying growing divergence among the two groups in real terms, notwithstanding EU emphasis on real convergence. Indicators disaggregated by sectors show that for CEECs specialization/agglomeration change most in agriculture, market services and manufacturing. The paper focuses on the last two sectors. It argues that performance in the service sector is largely due to capital regions catching up on previous underdevelopment in the sector, therefore getting closer to Western regions. Non-capital regions instead lag behind, moving away from the EU sectoral average. As far as manufacturing is concerned, CEECs regions continue to specialize in the more traditional lines of production, for which also agglomeration remains extremely high. Consideration of the changes over time gives a partially different picture and shows that the higher specialization in overall manufacturing results from the development of a small but dynamic medium-high technology sub-sector that is significantly disseminated across regions, thus appearing to result from successful industrial restructuring and reconversion.

  16. Agglomeration Effects in South-South FDI

    OpenAIRE

    Alessia Amighini; Chiara Franco

    2012-01-01

    The progressive rise in the amount of South-South FDI flows has inspired a number of studies to account for possible determinants. Using firm-level data on FDI flows from 2003 until 2011, we examine what determines green field FDI among the group of low and middle income countries (South-South FDI), with special regard to the role played by agglomeration economies. We separately consider manufacturing and services sectors. Our main findings confirm the hypotheses according to which both count...

  17. Early agglomeration monitor of coarse cohesive particles

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xi; You Changfu; Yang Ruichang, E-mail: xiwang06@mails.tsinghua.edu.c, E-mail: youcf@tsinghua.edu.c, E-mail: yangrc@mail.tsinghua.edu.c [Key laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China)

    2009-02-01

    This paper established a three-dimensional visualization experimental system. Paraffin particles were chosen as a test of raw material to simulate the movement and bonded process of coarse cohesive particles. Experimental study on fluidization process of coarse cohesive particles has been done by high-speed camera. The study shows that: from the normal fluidization to shut-down, it can be divided into two phases. The former is a slower phase of the bond and the formation of core grew up phase; the second stage is the huge bonded core turn to bridge fast and shutdown happens with great velocity. Then, comparison of different methods has been done to deal with the experimental date of pressure, the results show that: Compared to the average pressure and pressure deviation method, S attractor method that is based on chaotic theory could monitor the agglomeration much earlier, reflect the degrees of bond with the specific numerical value and also demonstrate the velocity of agglomeration. Thus, it could be applied to the early monitor of agglomeration of coarse cohesive particles.

  18. École d’été sur l’agriculture urbaine (troisième édition)

    OpenAIRE

    2011-01-01

    Pour une troisième année consécutive le Collectif de recherche sur l’aménagement paysager et l’agriculture urbaine durable (CRAPAUD), en association avec l’Institut des sciences de l’environnement, vous convie à cinq jours de formation sur l’agriculture urbaine (AU) et ses différentes facettes. Cette école se veut un creuset multidisciplinaire à l’émergence de l’agriculture urbaine. Il se veut un lieu et moment de rencontre entre les différents acteurs de l’agriculture urbaine au Québec, mais...

  19. Les métropoles et la nouvelle critique urbaine

    Directory of Open Access Journals (Sweden)

    Pierre Hamel

    2010-07-01

    Full Text Available La perspective critique élaborée par Henri Lefebvre demeure pertinente pour penser les rapports sociaux à l’espace, y inclus ceux qu’on observe dans les métropoles contemporaines en Amérique du Nord. En examinant la controverse autour de la forme urbaine telle que celle-ci a été remise à l’ordre du jour dans les années 1990 à la faveur du discours néorégionaliste, ce texte pose la question de l’avenir des métropoles et du modèle de ville dans lequel on souhaite vivre. La thèse défendue peut se résumer comme suit : afin de faire échec à la position libérale qui accorde la préséance aux facteurs économiques et aux forces du marché, les acteurs sociaux doivent porter le débat autour de la forme urbaine sur le terrain politique. À cette fin, l’urgence demeure de mobiliser la communauté politique.Henri Lefebvre’s critical approach remains appropriate for thinking about social relationships to space, including those we can now assess in North American metropolis. Through analyzing the controversy about the urban form as it has been highlighted again during the nineties and favored by the new regionalist discourse, this paper poses the question of the future of metropolis and the posterity of the urban model in which one wishes to live. Its thesis could be summarized like this : in order to make fail the liberal position which privileges to economical factors and market forces, social actors have to orientate the debate about the urban form towards the political field. In such a perspective, the emergency remains to mobilize the polity.

  20. Aluminum agglomeration involving the second mergence of agglomerates on the solid propellants burning surface: Experiments and modeling

    Science.gov (United States)

    Ao, Wen; Liu, Xin; Rezaiguia, Hichem; Liu, Huan; Wang, Zhixin; Liu, Peijin

    2017-07-01

    The agglomeration of aluminum particles usually occurs on the burning surface of aluminized composite propellants. It leads to low propellant combustion efficiency and high two-phase flow losses. To reach a thorough understanding of aluminum agglomeration behaviors, agglomeration processes, and particles size distribution of Al/AP/RDX/GAP propellants were studied by using a cinephotomicrography experimental technique, under 5 MPa. Accumulation, aggregation, and agglomeration phenomena of aluminum particles have been inspected, as well as the flame asymmetry of burning agglomerates. Results reveals that the dependency of the mean and the maximum agglomeration diameter to the burning rate and the virgin aluminum size have the same trend. A second-time mergence of multiple agglomerates on the burning surface is unveiled. Two typical modes of second mergence are concluded, based upon vertical and level movement of agglomerates, respectively. The latter mode is found to be dominant and sometimes a combination of the two modes may occur. A new model of aluminum agglomeration on the burning surface of composite propellants is derived to predict the particulates size distribution with a low computational amount. The basic idea is inspired from the well-known pocket models. The pocket size of the region formed by adjacent AP particles is obtained through scanning electron microscopy of the propellant cross-section coupled to an image processing method. The second mergence mechanism, as well as the effect of the burning rate on the agglomeration processes, are included in the present model. The mergence of two agglomerates is prescribed to occur only if their separation distance is less than a critical value. The agglomerates size distribution resulting from this original model match reasonably with the experimental data. Moreover, the present model gives superior results for mean agglomeration diameter compared to common empirical and pocket models. The average prediction

  1. Models of agglomeration and glass transition

    CERN Document Server

    Kerner, Richard

    2007-01-01

    This book is for any physicist interested in new vistas in the domain of non-crystalline condensed matter, aperiodic and quasi-crystalline networks and especially glass physics and chemistry. Students with an elementary background in thermodynamics and statistical physics will find the book accessible. The physics of glasses is extensively covered, focusing on their thermal and mechanical properties, as well as various models leading to the formation of the glassy states of matter from overcooled liquids. The models of agglomeration and growth are also applied to describe the formation of quasicrystals, fullerenes and, in biology, to describe virus assembly pathways.

  2. Agglomeration defects on irradiated carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Steini Moura, Cassio [Faculty of Physics, Pontificia Universidade Catolica do Rio Grande do Sul, 90619-900, Porto Alegre, RS (Brazil); Balzaretti, Naira Maria; Amaral, Livio [Institute of Physics, Universidade Federal do Rio Grande do Sul, C.P.: 15051, 91501-070, Porto Alegre, RS (Brazil); Gribel Lacerda, Rodrigo; Pimenta, Marcos A. [Universidade Federal de Minas Gerais, C.P.: 702, 31270-901, Belo Horizonte, MG (Brazil)

    2012-03-15

    Aligned carbon nanotubes (CNT) were irradiated in the longitudinal and perpendicular directions, with low energy carbon and helium ions in order to observe the formation of defects in the atomic structure. Analysis through Raman spectroscopy and scanning electron microscopy indicated bundle rupture and ion track formation on nanotube bundles. Aligned CNT presented a kind of defect comprising ravine formation and tube agglomeration on top of the substrate. The latter structure is possibly caused by static charge accumulation induced by the incoming ions. Fluence plays a role on the short range order. Higher fluence irradiation transforms CNT into amorphous carbon nanowires.

  3. Agglomeration defects on irradiated carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Cássio Stein Moura

    2012-03-01

    Full Text Available Aligned carbon nanotubes (CNT were irradiated in the longitudinal and perpendicular directions, with low energy carbon and helium ions in order to observe the formation of defects in the atomic structure. Analysis through Raman spectroscopy and scanning electron microscopy indicated bundle rupture and ion track formation on nanotube bundles. Aligned CNT presented a kind of defect comprising ravine formation and tube agglomeration on top of the substrate. The latter structure is possibly caused by static charge accumulation induced by the incoming ions. Fluence plays a role on the short range order. Higher fluence irradiation transforms CNT into amorphous carbon nanowires.

  4. The soundscape dynamics of human agglomeration

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Haroldo V; De Souza, Rodolfo T; Lenzi, Ervin K; Mendes, Renio S; Evangelista, Luiz R, E-mail: hvr@dfi.uem.br [Departamento de Fisica, Universidade Estadual de Maringa, Av. Colombo 5790, 87020-900 Maringa, PR (Brazil)

    2011-02-15

    We report on a statistical analysis of the people agglomeration soundscape. Specifically, we investigate the normalized sound amplitudes and intensities that emerge from human collective meetings. Our findings support the existence of non-trivial dynamics characterized by heavy tail distributions in the sound amplitudes, long-range correlations in the sound intensity and non-exponential distributions in the return interval distributions. Additionally, motivated by the time-dependent behavior present in the volatility/variance series, we compare the observational data with those obtained from a minimalist autoregressive stochastic model, namely the generalized autoregressive conditional heteroskedastic process (the GARCH process), and find that there is good agreement.

  5. Contributions to assessing the relative dimension of agglomeration theories

    Directory of Open Access Journals (Sweden)

    Ion POHOAŢĂ

    2013-04-01

    Full Text Available The aim of this paper is to structure, from a historical and spatial point of view, the existing specialists' concerns in developing theories about agglomeration. The complete and complex evaluation of agglomeration economies allows us to make important contributions to assessing the relative dimension of agglomeration theories, placing them within the research area of spatial economy and identifying them with the science of location and currently with the new economic geography (NEG.

  6. The Determinants of Agglomeration Economies in Indonesia and the Philippines

    OpenAIRE

    Umar Juoro

    1989-01-01

    The paper chiefly measures agglomeration economies in both the production and consumption sectors in Indonesia and the Philippines. Its empirical model estimates the returns to scale parameter which represents localization economies for three-digit manufacturing, and urbanization economies for the entire consumer service sector. Regression results confirm the role of agglomeration economies in explaining the concentration of producers and consumers in large urban areas. Agglomeration economie...

  7. Optimization of some parameters on agglomeration performance of Zonguldak bituminous coal by oil agglomeration

    Energy Technology Data Exchange (ETDEWEB)

    N. Aslan; I. Unal [Cumhuriyet University, Sivas (Turkey). Mining Engineering Department

    2009-03-15

    In this study, the optimization of some parameters on agglomeration performance of Zonguldak bituminous coal by oil agglomeration was discussed. A three-level Box-Behnken design combining with a response surface methodology (RSM) and quadratic programming (QP) were employed for modeling and optimization some operations parameters on oil agglomeration performance. The relationship between the responses, i.e., grade and recovery, and four process parameters, i.e., amount of oil, agitation time, agitation rate and solid content were presented as empirical model equations for both grade and recovery on oil agglomeration. The model equations were then optimized individually using the quadratic programming method to maximize both for grade and recovery within the experimental range studied. The optimum conditions were found to be 14.61% for amount of oil, 8.94 min for agitation time, 1554 rpm for agitation rate and 5% for solid content to achieve the maximum grade. The maximum model prediction of 0.650 grade at these optimum conditions is higher than any value obtained in the initial tests conducted. Similarly, the conditions for maximum recovery were found to be 20.60% for amount of oil, 5 min for agitation time, 1800 rpm for agitation rate and 19.48% for solid content with a prediction of 96.90% recovery, which is also higher than any other recovery obtained in the initial tests conducted. 34 refs., 5 figs., 7 tabs.

  8. Kinetic energy density and agglomerate abrasion rate during blending of agglomerates into powders

    NARCIS (Netherlands)

    Willemsz, Tofan A; Hooijmaijers, Ricardo; Rubingh, Carina M; Tran, Thanh N; Frijlink, Henderik W; Vromans, Herman; van der Voort Maarschalk, Kees

    2012-01-01

    Problems related to the blending of a cohesive powder with a free flowing bulk powder are frequently encountered in the pharmaceutical industry. The cohesive powder often forms lumps or agglomerates which are not dispersed during the mixing process and are therefore detrimental to blend uniformity.

  9. La gestion de l'eau dans les milieux urbains et ruraux, élément ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    La gestion de l'eau dans les milieux urbains et ruraux, élément fondamental des villes qui savent s'adapter aux changements climatiques. Les changements climatiques et l'urbanisation auront des implications en amont et en aval des villes d'Afrique, soit la demande urbaine en eau potable et eau agricole et la production ...

  10. Rapid determination of plasmonic nanoparticle agglomeration status in blood.

    Science.gov (United States)

    Jenkins, Samir V; Qu, Haiou; Mudalige, Thilak; Ingle, Taylor M; Wang, Rongrong; Wang, Feng; Howard, Paul C; Chen, Jingyi; Zhang, Yongbin

    2015-05-01

    Plasmonic nanomaterials as drug delivery or bio-imaging agents are typically introduced to biological systems through intravenous administration. However, the potential for agglomeration of nanoparticles in biological systems could dramatically affect their pharmacokinetic profile and toxic potential. Development of rapid screening methods to evaluate agglomeration is urgently needed to monitor the physical nature of nanoparticles as they are introduced into blood. Here, we establish novel methods using darkfield microscopy with hyperspectral detection (hsDFM), single particle inductively-coupled plasma mass spectrometry (spICP-MS), and confocal Raman microscopy (cRM) to discriminate gold nanoparticles (AuNPs) and their agglomerates in blood. Rich information about nanoparticle agglomeration in situ is provided by hsDFM monitoring of the plasmon resonance of primary nanoparticles and their agglomerates in whole blood; cRM is an effective complement to hsDFM to detect AuNP agglomerates in minimally manipulated samples. The AuNPs and the particle agglomerates were further distinguished in blood for the first time by quantification of particle mass using spICP-MS with excellent sensitivity and specificity. Furthermore, the agglomeration status of synthesized and commercial NPs incubated in blood was successfully assessed using the developed methods. Together, these complementary methods enable rapid determination of the agglomeration status of plasmonic nanomaterials in biological systems, specifically blood. Published by Elsevier Ltd.

  11. A new process based agglomeration parameter to characterize ceramic powders

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishna, Palanki [Nuclear Fuel Complex, 17-1-391/44 Subrahmanya Nagar, Saidabad, Hyderabad 500 059, Andhra Pradesh (India)], E-mail: bpalanki@rediffmail.com; Narasimha Murty, B.; Anuradha, M. [Nuclear Fuel Complex, 17-1-391/44 Subrahmanya Nagar, Saidabad, Hyderabad 500 059, Andhra Pradesh (India)

    2009-02-15

    Uranium dioxide powders are made through aqueous chemical route involving precipitation, drying, calcination and reduction. The presence of agglomerates causes powder packing difficulties in the compaction die, and non-uniform and incomplete densification on sintering. To quantify the degree of agglomeration, several authors have proposed 'Agglomeration Parameters'. The change in BET specific surface area of calcined U{sub 3}O{sub 8} upon reduction to UO{sub 2} per unit temperature difference is a simple new measure of agglomeration in uranium dioxide powders.

  12. Agglomeration of biomass fired fluidized bed gasifier and combustor

    Energy Technology Data Exchange (ETDEWEB)

    Mettanant, V.; Basu, P. [Dalhousie Univ., Halifax, NS (Canada). Dept. of Mechanical Engineering; Butler, J. [Greenfield Research Inc., Halifax, NS (Canada)

    2009-10-15

    As a renewable energy, biomass has the potential to supplement or replace energy produced from fossil fuel resources. However, agglomeration can occur in the fluidized bed boilers and gasifiers used to generate biomass energy. This paper discussed the theoretical and experimental results obtained during an agglomeration study of a biomass-fired fluidized bed gasifier and combustor. The mechanisms of agglomeration were studied as well as influence of various biomass components on bed materials. The study showed that agglomeration is typically caused by the formation of low melting point eutectic mixtures in the bed through a reaction of alkali materials in the fuel with silica bed materials. Agglomeration is also prompted by reactions between alkali species in ash and silica. Beds firing coffee husks, cotton husks, wastes and soy husks have the highest agglomeration problems, while peat, wood, and sewage sludge burn without agglomeration due to their low agglomeration index. The use of alternative bed materials instead of silica sands was recommended. It was concluded that the co-combustion of biomass with coal and other fuels will also prevent agglomerates from forming. 50 refs., 9 tabs., 39 figs.

  13. Modeling of crushed ore agglomeration for heap leach operations

    Science.gov (United States)

    Dhawan, Nikhil

    The focus of this dissertation is modeling of the evolution of size distribution in batch agglomeration drum. There has been no successful work on modeling of crushed ore agglomeration although the framework for population balance modeling of pelletization and granulation is readily available. In this study three different batch agglomeration drums were used to study the agglomeration kinetics of copper, gold and nickel ores. The agglomerate size distribution is inherently subject to random fluctuation due the very nature of the process. Yet, with careful experimentation and size analysis the evolution of size distribution can be followed. The population balance model employing the random coalesce model with a constant rate kernel was shown to work well in a micro and lab scale agglomerator experiments. In small drums agglomerates begin to break in a short time, whereas the growth is uniform in the lab scale drum. The experimental agglomerate size distributions exhibit self-preserving size spectra which confirms the applicability of coalescence rate based model. The same spectra became a useful fact for predicting the size distribution with an empirical model. Since moisture is a principal variable, the absolute deviation from optimum moisture was used as the primary variable in the empirical model. Having established a model for the size distribution, the next step was to delve into the internal constituents of each agglomerate size class. To this end, an experimental scheme known as dip test was devised. The outcome of the test was the size distribution of progeny particles which make up a given size class of agglomerate. The progeny size distribution was analyzed with a model that partitions the particles into a host and guest category. The ensuing partition coefficient is a valuable in determining how a particle in a size class participates in larger agglomerates. This dissertation lays out the fundamentals for applying the population balance concept to batch

  14. Development and Application of Agglomerated Multigrid Methods for Complex Geometries

    Science.gov (United States)

    Nishikawa, Hiroaki; Diskin, Boris; Thomas, James L.

    2010-01-01

    We report progress in the development of agglomerated multigrid techniques for fully un- structured grids in three dimensions, building upon two previous studies focused on efficiently solving a model diffusion equation. We demonstrate a robust fully-coarsened agglomerated multigrid technique for 3D complex geometries, incorporating the following key developments: consistent and stable coarse-grid discretizations, a hierarchical agglomeration scheme, and line-agglomeration/relaxation using prismatic-cell discretizations in the highly-stretched grid regions. A signi cant speed-up in computer time is demonstrated for a model diffusion problem, the Euler equations, and the Reynolds-averaged Navier-Stokes equations for 3D realistic complex geometries.

  15. Morphologie urbaine et mobilité en marche à pied

    Directory of Open Access Journals (Sweden)

    Jean-Christophe Foltête

    2003-10-01

    Full Text Available L’objectif de ce travail est de mieux comprendre les déterminants de la mobilité quotidienne en marche à pied. Il est fondé sur l’hypothèse selon laquelle la morphologie urbaine conditionne partiellement les comportements de mobilité piétonnière en définissant la qualité de l’accessibilité à pied. La vérification de cette hypothèse s’appuie sur des données originales portant sur les déplacements pédestres quotidiens à Besançon et à Lille. Ces données décrivant les pratiques en marche à pied, y compris les parcours empruntés, ont été collectées grâce à deux enquêtes téléphoniques, puis implémentées dans un Système d’Information Géographique.   Conformément à l’hypothèse de travail, il s’avère qu’une bonne qualité d’accessibilité pour le mode piétonnier au départ du domicile a tendance à favoriser quantitativement la pratique de la marche à pied. L’analyse des trajets possibles à réaliser à pied mais effectués par un autre mode conforte ce rôle de la structure, en montrant notamment que l’efficacité du réseau de voirie influence les pratiques piétonnières, en particulier le choix modal. Par ailleurs, l’intensité du trafic pédestre (qu’il soit local ou de transit s’avère dépendre partiellement de la qualité de l’accessibilité piétonnière locale et ce d’autant plus que la structure urbaine s’organise autour d’un centre unique. Enfin, parmi les descripteurs de l’occupation du sol susceptibles d’expliquer la fréquentation des marcheurs, la fragmentation spatiale se révèle jouer un rôle important comme incitateur à l’usage de la marche.  

  16. The distribution, atmospheric transfer, and assessment of krypton-85; Distribution, transfert atmospherique et bilan du krypton-85

    Energy Technology Data Exchange (ETDEWEB)

    Pannetier, R. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-06-01

    Techniques for sampling and measuring krypton-85 have been developed which allowed to determine its geographical distribution. From its use as a tracer, an evaluation of the air masses which cross over the subtropical fronts has been derived. Besides, the stratospheric character of air pollution by krypton-85 at the level of the antarctic soil has been shown out. Levels of krypton-85 seem to point out to an underestimation of the assessment of nuclear explosion fission energies as adopted by the United Nations Scientific committee on the effects of atomic radiation and emphasize the need to set limits as soon as possible to the amounts of krypton-85 released to the atmosphere by fuel-reprocessing plants. (author) [French] La mise au point de techniques de prelevement et de mesure du krypton-85 atmospherique a permis de determiner sa repartition geographique. De son utilisation comme traceur on deduit une evaluation des masses d'air qui traversent les fronts subtropicaux. Par ailleurs, le caractere stratospherique de la pollution de l'air par le krypton-85 au niveau du sol antarctique est mis en evidence. Le bilan du krypton-85 semble reveler une sous-estimation du bilan des energies de fission des explosions adopte par le Comite scientifique des Nations Unies et souligne la necessite de limiter des que possible les quantites de krypton-85 rejetees dans l'atmosphere par les usines de traitement de combustibles irradies. (auteur)

  17. Influence of excipients and processing conditions on the development of agglomerates of racecadotril by crystallo-co-agglomeration.

    Science.gov (United States)

    Garala, Kevin; Patel, Jaydeep; Patel, Anjali; Raval, Mihir; Dharamsi, Abhay

    2012-10-01

    The purpose of the present investigation was to improve the flow and mechanical properties of racecadotril by a crystallo-co-agglomeration (CCA) technique. Direct tableting is a requirement of pharmaceutical industries. Poor mechanical properties of crystalline drug particles require wet granulation which is uneconomical, laborious, and tedious. The objective of this work was to study the influence of various polymers/excipients and processing conditions on the formation of directly compressible agglomerates of the water-insoluble drug, racecadotril, an antidiarrheal agent. The agglomerates of racecadotril were prepared using dichloromethane (DCM)-water as the crystallization system. DCM acted as a good solvent for racecadotril as well as a bridging liquid for the agglomeration of the crystallized drug and water as the nonsolvent. The prepared agglomerates were tested for micromeritic and mechanical properties. The process yielded ~90 to 96% wt/ wt spherical agglomerates containing racecadotril with the diameter between 299 and 521 μ. A higher rotational speed of crystallization system reduces the size of the agglomerates and disturbs the sphericity. Spherical agglomerates were generated with a uniform dispersion of the crystallized drug. CCA showed excellent flowability and crushing strength. Excipients and processing conditions can play a key role in preparing spherical agglomerates of racecadotril by CCA, an excellent alternative to the wet granulation process to prepare intermediates for direct compression.

  18. Mobilité urbaine et politique de transport à Yaoundé

    OpenAIRE

    Mfoulou Olugu, Jean Patrick

    2016-01-01

    La mobilité urbaine à Yaoundé comme dans la majorité des agglomérations à forte croissance urbaine en Afrique est dominée par des véhicules de petite capacité comme les taxis collectifs et moto-taxis. Ce phénomène a comme conséquence une augmentation des externalités négatives comme la congestion, les accidents, la pollution, et des coûts monétaires élevés à supporter par les usagers des transports. L'objectif de ce policybrief est d'informer les communautés urbaines en Afrique ou à Yaoundéno...

  19. Modes d’habiter urbains et ruraux : entre continuité et rupture Urban and rural lifestyles: Between continuity and break

    Directory of Open Access Journals (Sweden)

    Samuel Carpentier

    2010-01-01

    Full Text Available Le passage de la ville à l’urbain a marqué l’avènement d’une société postmoderne dans laquelle la polarisation de plus en plus forte des agglomérations sur l’espace local devait conduire à un nivellement des modes de vie. Le processus de périurbanisation, en cours depuis plusieurs décennies, illustre cette diffusion physique et sociale de l’urbain vers des espaces toujours plus éloignés et dépendants de la ville-centre. La problématique de cet article consiste alors à voir s’il existe, de la ville aux zones rurales, des gradients d’urbanité en fonction des caractéristiques morphologiques (notamment les densités et fonctionnelles (illustrées par la mobilité de ces espaces. Pour ce faire, une typologie de communes a été élaborée pour caractériser des types d’ancrages résidentiels. Ensuite, une enquête a permis de collecter les pratiques et les représentations de l’habitat et de la mobilité au Luxembourg (N=600 en 2005, en fonction de la zone de résidence des individus. Dès lors, les rapports urbain/rural sont analysés au regard des modes d’habiter, c’est-à-dire de la spatialisation des modes de vie en fonction du couple ancrage/mobilité. Les résultats obtenus mettent en lumière à la fois des gradients comportementaux (tant en termes de pratiques que de représentations, témoignant d’une certaine continuité urbain/rural, et des ruptures qui soulignent certaines spécificités des espaces ruraux.The metropolization process marked the advent of a postmodern society in which the growing polarization of agglomerations on local space would lead to a levelling of lifestyles. The decades-old process of suburbanization illustrates the physical and social diffusion of urban features towards more and more distant spaces, which thus become dependent on the city-center. This paper therefore aims at exploring whether urban gradients can be identified when moving from the city to rural areas. Such

  20. Overpopulated, Underdeveloped Urban Agglomerations: Tomorrow’s Unstable Operating Environment

    Science.gov (United States)

    2012-05-08

    DATES COVERED (From - To) 4. TITLE AND SUBTITLE Overpopulated , Underdeveloped Urban Agglomerations: Tomorrow’s 5a. CONTRACT NUMBER...ABSTRACT This paper asserts that a unique future operational environment is developing: overpopulated , underdeveloped urban agglomerations. A...proposed definition for this operating environment is (or would be) an overpopulated urban area which is located within a developing or underdeveloped

  1. Where do cities form? A geographical agglomeration model for Europe

    NARCIS (Netherlands)

    Stelder, T.M.

    2005-01-01

    In the recent literature on spatial agglomeration models, substantial progress has been made in modeling urban structures in terms of number and size of cities, but the question where cities arise remains unanswered. This paper illustrates that if a spatial agglomeration model is extended with a

  2. Temporal Trends in Agglomeration Economies amongst Firms in the ...

    African Journals Online (AJOL)

    The paper concluded that agglomeration policy could be a potent tool of economic revival, through its multiplier effects on the economy of a region. It is however recommended that agglomeration of firms should be encouraged and strengthened through active participation of government in the industrial sector, giving tax ...

  3. The Role of Magnesium and Calcium in Governing Yeast Agglomeration

    Directory of Open Access Journals (Sweden)

    Rosslyn M. Birch

    2002-01-01

    Full Text Available »Grit« formation by agglomerating cells of baker’s yeast is an idiosyncratic phenomenon of irreversible cellular aggregation that is detrimental to yeast quality. Agglomeration results in failure of rehydrated dried yeast to evenly resuspend and has economic consequences for both yeast manufacturers and bakers. Several environmental factors are implicated in governing yeast agglomeration, but no significant differences between 'gritty' and 'non-gritty' yeast in terms of cell hydrophobicity or flocculence have been reported. In this study, analysis of cellular metal ions has revealed high levels of calcium in 'gritty' strains of Saccharomyces cerevisiae, which suggests that calcium ions may positively influence agglomeration. In contrast, it was found that cellular magnesium levels were higher in 'non-gritty' yeast. Furthermore, by increasing magnesium concentrations in molasses yeast growth media, a reduction in cellular calcium was observed and this concomitantly reduced the tendency of cells to agglomerate and form grit. Magnesium thus acted antagonistically against calcium-induced agglomeration, possibly by blocking calcium binding to yeast cell surface receptors. Results suggested that yeast agglomeration and metal ion bioavailability were inextricably linked and the findings are discussed in relation to possible measures of alleviating cellular agglomeration in the production of baker’s yeast.

  4. Effects of gas conditions on ASH induced agglomeration

    DEFF Research Database (Denmark)

    Ma, T.; Fan, C. G.; Hao, L. F.

    2016-01-01

    on agglomeration tendency with two types of biomass ash, including rice straw and wheat straw ash. The agglomerates are analyzed by SEM-EDS for morphology and elemental composition. Defluidization temperature (Td) in those two types of gas conditions is quite different. Tdin gasification condition is much lower...

  5. Agglomeration multigrid for viscous turbulent flows

    Science.gov (United States)

    Mavriplis, D. J.; Venkatakrishnan, V.

    1994-01-01

    Agglomeration multigrid, which has been demonstrated as an efficient and automatic technique for the solution of the Euler equations on unstructured meshes, is extended to viscous turbulent flows. For diffusion terms, coarse grid discretizations are not possible, and more accurate grid transfer operators are required as well. A Galerkin coarse grid operator construction and an implicit prolongation operator are proposed. Their suitability is evaluated by examining their effect on the solution of Laplace's equation. The resulting strategy is employed to solve the Reynolds-averaged Navier-Stokes equations for aerodynamic flows. Convergence rates comparable to those obtained by a previously developed non-nested mesh multigrid approach are demonstrated, and suggestions for further improvements are given.

  6. Cultiver les milieux habités : quelle agronomie en zone urbaine ?

    OpenAIRE

    Aubry, Christine

    2011-01-01

    L'agriculture urbaine et l'alimentation des villes forment un champ de préoccupations foisonnant. Cet article examine les questions de recherche adressées à l'agronomie. Les exploitations agricoles périurbaines, les pratiques des agriculteurs, les organisations territoriales agri-urbaines, les circuits courts alimentaires et les produits résiduaires organiques, sont pris comme exemples pour les éclairer. Cultiver les milieux habités est un enjeu de recherche et de formation des futurs agronom...

  7. Study on the agglomeration kinetics of uranium peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, M.; Mojica Rodriguez, L.A. [CEA, Centre de Marcoule, Nuclear Energy Division, RadioChemistry and Process Department, 17171, Bagnols-sur-Ceze 30207 (France); Muhr, H.; Plasari, E. [Reaction and Process Engineering Laboratory, CNRS, University of Lorraine. 1 rue Grandville, BP 20451, Nancy 54001 (France); Auger, F. [Areva Mines/SEPA. 2 route de Lavaugrasse, Bessines-sur-Gartempe 87250 (France)

    2016-07-01

    Considering the previous study dealing with thermodynamic and kinetic phenomena (nucleation and crystal growth) during the uranium peroxide precipitation, this work focuses on the agglomeration mechanism. It provides the results obtained from the experiments carried out in a mixed suspension - mixed product removal (MSMPR) mixer operating at steady state. The influence of the operating parameters on the uranium peroxide agglomerates was studied in order to identify the agglomeration kernel. The method is based on the resolution of the population balance equation using the method of moments and the experimental particle size distributions. The results lead to a size-independent kernel directly proportional to the crystal growth rate. Under the stirring conditions studied, the agglomeration appears to be significantly reduced by mixing which results in a kernel inversely proportional to the average shear rate. The agglomeration kinetic law obtained in this study will be used for the process modelling in a further study. (authors)

  8. Effects of gas conditions on ASH induced agglomeration

    DEFF Research Database (Denmark)

    Ma, T.; Fan, C. G.; Hao, L. F.

    2016-01-01

    Agglomeration is a serious problem for gasification and combustion of biomass in fluidized bed. Agglomeration characteristics may be affected by gas condition, but the literature is quite vague in this regard. This study focuses on the effects of gasification and combustion condition...... on agglomeration tendency with two types of biomass ash, including rice straw and wheat straw ash. The agglomerates are analyzed by SEM-EDS for morphology and elemental composition. Defluidization temperature (Td) in those two types of gas conditions is quite different. Tdin gasification condition is much lower...... than that in combustion condition. Agglomeration in both combustion and gasification conditions are melting-induced, the lower Tdin gasification condition may be caused by the transformation of K2SO4....

  9. Agglomeration multigrid for the three-dimensional Euler equations

    Science.gov (United States)

    Venkatakrishnan, V.; Mavriplis, D. J.

    1994-01-01

    A multigrid procedure that makes use of coarse grids generated by the agglomeration of control volumes is advocated as a practical approach for solving the three dimensional Euler equations on unstructured grids about complex configurations. It is shown that the agglomeration procedure can be tailored to achieve certain coarse grid properties such as the sizes of the coarse grids and aspect ratios of the coarse grid cells. The agglomeration is done as a preprocessing step and runs in linear time. The implications for multigrid of using arbitrary polyhedral coarse grids are discussed. The agglomeration multigrid technique compares very favorably with existing multigrid procedures both in terms of convergence rates and elapsed times. The main advantage of the present approach is the ease with which coarse grids of any desired degree of coarseness may be generated in three dimensions, without being constrained by considerations of geometry. Inviscid flows over a variety of complex configurations are computed using the agglomeration multigrid strategy.

  10. WP/084 Measuring Industry Agglomeration and Identifying the Driving Forces

    DEFF Research Database (Denmark)

    Howard, Emma; Tarp, Finn; Newman, Carol

    Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We propose a new measure and examine what it reveals about the importance of transp......Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We propose a new measure and examine what it reveals about the importance...... of transport costs, labour market pooling, and technology transfer for agglomeration processes. We contrast this analysis with insights from existing measures in the literature and find very different underlying stories at work. An exceptionally rich set of data from Vietnam makes us confident that our measure...

  11. Novel Binders and Methods for Agglomeration of Ore

    Energy Technology Data Exchange (ETDEWEB)

    S. K. Kawatra; T. C. Eisele; K. A. Lewandowski; J. A. Gurtler

    2006-09-30

    Heap leaching is one of the methods being used to recover metal from low grade ore deposits. The main problem faced during heap leaching is the migration of fine grained particles through the heap, forming impermeable beds which result in poor solution flow. The poor solution flow leads to less contact between the leach solution and the ore, resulting in low recovery rates. Agglomeration of ore into coarse, porous masses prevents fine particles from migrating and clogging the spaces and channels between the larger ore particles. Currently, there is one facility in the United States which uses agglomeration. This operation agglomerates their ore using leach solution (raffinate), but is still experiencing undesirable metal recovery from the heaps due to agglomerate breakdown. The use of a binder, in addition to the leach solution, during agglomeration would help to produce stronger agglomerates that did not break down during processing. However, there are no known binders that will work satisfactorily in the acidic environment of a heap, at a reasonable cost. As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. Increasing copper recovery in heap leaching by the use of binders and agglomeration would result in a significant decrease in the amount of energy consumed. Assuming that 70% of all the leaching heaps would convert to using agglomeration technology, as much as 1.64*10{sup 12} BTU per year would be able to be saved if a 25% increase in copper recovery was experienced, which is equivalent to saving approximately 18% of the energy currently being used in leaching heaps. For every week a leach cycle was decreased, a savings of as much as 1.23*10{sup 11} BTU per week would result. This project has identified several acid-resistant binders and agglomeration procedures. These binders and experimental procedures will be able to be used for use in improving the energy efficiency of

  12. De-agglomeration mechanisms of TiO{sub 2} aerosol agglomerates in PWR steam generator tube rupture conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lind, Terttaliisa, E-mail: terttaliisa.lind@psi.c [Paul Scherrer Institute, Laboratory of Thermal-Hydraulics, Nuclear Energy and Safety Department, CH-5232 Villigen PSI (Switzerland); Ammar, Yasmine [Paul Scherrer Institute, Laboratory of Thermal-Hydraulics, Nuclear Energy and Safety Department, CH-5232 Villigen PSI (Switzerland); School of Mechanical and Systems Engineering, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom); Dehbi, Abdel; Guentay, Salih [Paul Scherrer Institute, Laboratory of Thermal-Hydraulics, Nuclear Energy and Safety Department, CH-5232 Villigen PSI (Switzerland)

    2010-08-15

    A steam generator tube rupture (SGTR) in a pressurized water reactor (PWR) might be a major source of accidental release of radioactive aerosols into the environment during severe accident due to its potential to by-pass the reactor containment. In the ARTIST program, tests were carried out at flow conditions typical to SGTR events to determine the retention of dry aerosol particles inside a steam generator tube. The experiments with TiO{sub 2} agglomerates showed that for high velocities in the range of 100-350 m/s, the average particle size at the outlet of the tube was significantly smaller than at the inlet due to particle de-agglomeration. Earlier, particle de-agglomeration has not been considered significant in nuclear reactor severe accidents. However, the tests in ARTIST program have shown that there is a possibility that TiO{sub 2} aerosol particles de-agglomerate inside a tube and in the expansion zone after the tube exit under SGTR conditions. In this investigation, we measured TiO{sub 2} aerosol de-agglomeration in the tube with very high flow velocities with two different TiO{sub 2} aerosols. The de-agglomeration was determined by measuring the size of the agglomerates at the inlet and outlet of the test section. The test section was composed of tubes with three different lengths, 0.20, 2.0 and 4.0 m, followed by an expansion zone. The main results were: (i) the de-agglomerate process was relatively insensitive to the initial particle size distribution, (ii) the agglomerates were observed to de-agglomerate in all the tubes, and the resulting particle size distributions were similar for both TiO{sub 2} aerosols, (iii) at high flow rates, increasing the gas mass flow rate did not produce further de-agglomeration, and (iv) the agglomerates did not de-agglomerate to primary particles. Instead, after de-agglomeration the particles had a median outer diameter D{sub c} = 1.1 {mu}m. Based on analysis using computational fluid dynamics (CFDs), the de-agglomeration

  13. Les organisations populaires à Quito et Guayaquil: forces et faiblesses de ces 'nouveaux' acteurs urbains

    Directory of Open Access Journals (Sweden)

    1991-01-01

    Full Text Available A partir de 1972 -- mise en exploitation des gisements pétroliers et accroissement des rentrées de devises -- l’état joue un rôle de plus en plus important dans l’orientation de la politique économique les migrations campagne / ville s’intensifient et la population rurale, chassée des campagnes par une réforme agraire qui se révèle être un demi-échec, vient grossir les effectifs des agglomérations. La politique urbaine déficiente, les erreurs de la planification et le manque d’intérêt de l’état envers les plus démunis, expliquent l’extension rapide des quartiers populaires. Les habitants tentent de résoudre, par leurs propres moyens, les problèmes les plus graves auxquels ils se heurtent (possession du sol urbain, dotation d’infrastructures… et que l’état ne peut ou ne veut pas résoudre. Les années soixante-dix voient les quartiers s’organiser et faire pression sur les autorités pour tenter d’apporter une solution aux problèmes qui les affectent quotidiennement. Ces mutations ont d’importantes répercussions sur la croissance des deux agglomérations et sur l’émergence puis la consolidation des organisations populaires. Il s’agit de faire le « bilan » actuel des organisations populaires, en insistant sur leurs forces et leurs faiblesses et sur l’aspect comparatif : ces organisations sont-elles aussi dynamiques à Quito qu’à Guayaquil ? Leurs objectifs et leurs stratégies sont-ils identiques ? Quelles sont leurs perspectives d’avenir ? Voici quelques questions auxquelles nous tenterons d’apporter des éléments de réponse. LAS ORGANIZACIONES POPULARES EN QUITO Y GUAYAQUIL: FUERZAS Y DEBILIDADES DE ESTOS « NUEVOS » ACTORES URBANOS. A partir de 1972 --cuando se inicia la explotación de yacimientos petroleros y se incrementan los ingresos en divisas--, el Estado juega un papel cada vez más importante en la orientación de la política económica las migraciones campo-ciudad se intensifican y la

  14. Spatial Linkage and Urban Expansion: AN Urban Agglomeration View

    Science.gov (United States)

    Jiao, L. M.; Tang, X.; Liu, X. P.

    2017-09-01

    Urban expansion displays different characteristics in each period. From the perspective of the urban agglomeration, studying the spatial and temporal characteristics of urban expansion plays an important role in understanding the complex relationship between urban expansion and network structure of urban agglomeration. We analyze urban expansion in the Yangtze River Delta Urban Agglomeration (YRD) through accessibility to and spatial interaction intensity from core cities as well as accessibility of road network. Results show that: (1) Correlation between urban expansion intensity and spatial indicators such as location and space syntax variables is remarkable and positive, while it decreases after rapid expansion. (2) Urban expansion velocity displays a positive correlation with spatial indicators mentioned above in the first (1980-1990) and second (1990-2000) period. However, it exhibits a negative relationship in the third period (2000-2010), i.e., cities located in the periphery of urban agglomeration developing more quickly. Consequently, the hypothesis of convergence of urban expansion in rapid expansion stage is put forward. (3) Results of Zipf's law and Gibrat's law show urban expansion in YRD displays a convergent trend in rapid expansion stage, small and medium-sized cities growing faster. This study shows that spatial linkage plays an important but evolving role in urban expansion within the urban agglomeration. In addition, it serves as a reference to the planning of Yangtze River Delta Urban Agglomeration and regulation of urban expansion of other urban agglomerations.

  15. SPATIAL LINKAGE AND URBAN EXPANSION: AN URBAN AGGLOMERATION VIEW

    Directory of Open Access Journals (Sweden)

    L. M. Jiao

    2017-09-01

    Full Text Available Urban expansion displays different characteristics in each period. From the perspective of the urban agglomeration, studying the spatial and temporal characteristics of urban expansion plays an important role in understanding the complex relationship between urban expansion and network structure of urban agglomeration. We analyze urban expansion in the Yangtze River Delta Urban Agglomeration (YRD through accessibility to and spatial interaction intensity from core cities as well as accessibility of road network. Results show that: (1 Correlation between urban expansion intensity and spatial indicators such as location and space syntax variables is remarkable and positive, while it decreases after rapid expansion. (2 Urban expansion velocity displays a positive correlation with spatial indicators mentioned above in the first (1980–1990 and second (1990–2000 period. However, it exhibits a negative relationship in the third period (2000–2010, i.e., cities located in the periphery of urban agglomeration developing more quickly. Consequently, the hypothesis of convergence of urban expansion in rapid expansion stage is put forward. (3 Results of Zipf’s law and Gibrat's law show urban expansion in YRD displays a convergent trend in rapid expansion stage, small and medium-sized cities growing faster. This study shows that spatial linkage plays an important but evolving role in urban expansion within the urban agglomeration. In addition, it serves as a reference to the planning of Yangtze River Delta Urban Agglomeration and regulation of urban expansion of other urban agglomerations.

  16. Novel Binders and Methods for Agglomeration of Ore

    Energy Technology Data Exchange (ETDEWEB)

    S. K. Kawatra; T. C. Eisele; K. A. Lewandowski; J. A. Gurtler

    2006-03-31

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily at a reasonable cost. A primary example of this is copper heap leaching, where there are no binders currently encountered in this acidic environment process. As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching. The active involvement of our industrial partners will help to ensure rapid commercialization of any agglomeration technologies developed by this project.

  17. Novel Binders and Methods for Agglomeration of Ore

    Energy Technology Data Exchange (ETDEWEB)

    S. K. Kawatra; T. C. Eisele; J. A. Gurtler; K. Lewandowski

    2005-09-30

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily at a reasonable cost. A primary example of this is copper heap leaching, where there are no binders currently encountered in this acidic environment process. As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching. The active involvement of our industrial partners will help to ensure rapid commercialization of any agglomeration technologies developed by this project.

  18. Fragmentation and bond strength of airborne diesel soot agglomerates

    Directory of Open Access Journals (Sweden)

    Messerer Armin

    2008-06-01

    Full Text Available Abstract Background The potential of diesel soot aerosol particles to break up into smaller units under mechanical stress was investigated by a direct impaction technique which measures the degree of fragmentation of individual agglomerates vs. impact energy. Diesel aerosol was generated by an idling diesel engine used for passenger vehicles. Both the aerosol emitted directly and aerosol that had undergone additional growth by Brownian coagulation ("aging" was investigated. Optionally a thermo-desoption technique at 280°C was used to remove all high-volatility and the majority of low-volatility HC adsorbates from the aerosol before aging. Results It was found that the primary soot agglomerates emitted directly from the engine could not be fragmented at all. Soot agglomerates permitted to grow additionally by Brownian coagulation of the primary emitted particles could be fragmented to a maximum of 75% and 60% respectively, depending on whether adsorbates were removed from their surface prior to aging or not. At most, these aged agglomerates could be broken down to roughly the size of the agglomerates from the primary emission. The energy required for a 50% fragmentation probability of all bonds within an agglomerate was reduced by roughly a factor of 2 when aging "dry" agglomerates. Average bond energies derived from the data were 0.52*10-16 and 1.2*10-16 J, respectively. This is about 2 orders of magnitude higher than estimates for pure van-der-Waals agglomerates, but agrees quite well with other observations. Conclusion Although direct conclusions regarding the behavior of inhaled diesel aerosol in contact with body fluids cannot be drawn from such measurements, the results imply that highly agglomerated soot aerosol particles are unlikely to break up into units smaller than roughly the size distribution emitted as tail pipe soot.

  19. Agriculture urbaine en Afrique de l'Ouest / Urban Agriculture in West ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Agriculture urbaine en Afrique de l'Ouest/ Urban Agriculture in West Africa. Une contribution à la sécurité alimentaire et à l'assainissement des villes/ Contributing to Food Security and Urban Sanitation. sous la direction de / edited by Olanrewaju B. Smith. Image. Publié conjointement par. Centre de recherches pour le ...

  20. Développement durable de l'agriculture urbaine en Afrique ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    , concepts et méthodes. Book cover Développement durable de l'agriculture urbaine en Afrique francophone : Enjeux, concepts. Editor(s):. Olanrewaju B. Smith, Paule Moustier, Luc. J.A. Mougeot, and Abdou Fall. Publisher(s):. CIRAD, IDRC.

  1. Gouvernance pour l'équité en santé en milieu urbain - susciter la ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Au Bangladesh, la prestation des services de santé traverse une crise en raison de l'expansion des bidonvilles. Un nouveau projet de recherche permettra de trouver des moyens d'améliorer les services offerts aux pauvres vivant en milieu urbain et de favoriser une plus grande participation des collectivités à la ...

  2. Gouvernance des systèmes alimentaires urbains pour la prévention ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Gouvernance des systèmes alimentaires urbains pour la prévention des maladies non transmissibles (MNT) en Afrique. Il y a un fardeau croissant par rapport aux maladies non transmissibles (MNT) à l'échelle de l'Afrique, attribuable en partie à la hausse des mauvaises habitudes alimentaires (y compris la consommation ...

  3. S'attaquer à la ségrégation urbaine : Autonomisation juridique dans ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Amérique latine. Il est estimé qu'en Amérique latine, huit personnes sur dix habitent en ville. Beaucoup de grands centres urbains fomentent de profondes inégalités. Plus de 29 % de la population vit sous le seuil de la pauvreté et 23,5 % vit ...

  4. Impact of biofuel in agglomeration process on production of pollutants

    Directory of Open Access Journals (Sweden)

    Lesko Jaroslav

    2017-01-01

    Full Text Available Production of agglomerate in the metallurgical company belongs among the largest sources of emissions damaging the environment. Effects of coke breeze substitution by charcoal, pine, and oak sawdust there were sintering performed in a laboratory agglomeration pan with substitution ratios of 14 % and 20 % by the emissions of CO2, CO, NOx and NO. Variations in the gas emissions might have been affected by physical and chemical properties of the input materials and the technological parameters of agglomeration. It is important and necessary to seek other methods and materials with which it would be possible to optimize the production of emissions and protect the environment.

  5. Evaluation of the sanitary impact of urban air pollution. Update version of the methodological guide; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Version actualisee du guide methodologique

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-03-15

    In order to bring a help to the evaluation of effects of air quality on health, the Institute of Sanitary surveillance published in 1999 a method guide for the realisation of sanitary impact evaluations of the urban air pollution. This work to prepare to an update version of the guide presents the first recommendations that can be made today for the realisation of sanitary impact evaluations at short and long term at a local level, taking into account the knowledge evolution. (N.C.)

  6. Evaluation of urban air pollution impact. Brest and Nantes impact at long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Brest et Nantes impact a long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The assessment for Brest and Nantes of the health impact in 1999 of chronic exposure to air pollution relies on four stages: health outcome identification, the selection of exposure-response functions, exposure assessment and risk characterization. The study characterizes: - the health gain due to a 25% decrease in air pollution levels; - the expected health impact of a 15% rise in air pollution levels. The results give the number of deaths attributable to air pollution. As for the health gain, the gain in days of life expectancy is also calculated. The study for Brest relies on one single exposure-response function. Concerning Nantes, the air control network is more complete and allows to use four exposure-response functions. The health gain due to a 25% decrease in air pollution levels is interpreted as a prudent evaluation of the health impact of air pollution. The estimated number of deaths due to the impact is around 38 (23 - 53) for Brest and around 40 (14 - 65) for Nantes. It means a decrease in the lifespan of 48 (29 - 68) days for Brest and 51 (17 - 84) days for Nantes. The uncertainty about exposure evaluation, the use of American exposure-response functions and of strong hypotheses to calculate the lifespan reduction generate more errors and uncertainty than for short term health impact assessment. (author)

  7. Epidemiological surveillance - air and health. Surveillance of effects on health linked to air pollution; Surveillance epidemiologique air et sante. Surveillance des effets sur la sante lies a la pollution atmospherique en milieu urbain

    Energy Technology Data Exchange (ETDEWEB)

    Quenel, Ph.; Cassadou, S.; Eilstein, D.; Filleul, L.; Le Goaster, C.; Le Tertre, A.; Medina, S.; Pascal, L.; Prouvost, H.; Saviuc, Ph.; Zeghnoun, A. [Institut National de Veille Sanitaire, 94 - Saint Maurice (France); Declerq, Ch. [Observatoire Regional de Sante Nord Pas de Calais (France)

    1999-03-01

    In the field of air pollution, the France is the first country to be endowed with a device of epidemiological surveillance allowing to to evaluate and monitor the impact of urban air pollution on the health of population. This new approach is based on the analysis of relationship between pollution indicators and health indicators, it leads to confirm the partnership between actors of environment and health, at the national level as well at the local level. It confirms the development of assessment in the field of environmental health. (N.C.)

  8. Quantification of years of life lost attributable to chronic air pollution exposure in a health impact assessment: the case of Nantes; Quantification des annees de vie perdues attribuables aux expositions chroniques a la pollution atmospherique urbaine: le cas de Nantes

    Energy Technology Data Exchange (ETDEWEB)

    Guillois-Becel, Y.; Eilstein, D.; Glorennec, Ph.; Lefranc, A

    2007-05-15

    Background: When French regional planning for air quality first began, exposure-response functions from time-series studies were used to assess the short-term health impact of urban air pollution. The World Health Organisation also suggests that exposure-response functions from cohort studies be taken into account to evaluate the effects of chronic exposure and to quantify the prematurity of deaths related to chronic exposure to air pollution. This work characterizes the long term effects of air pollution in Nantes by considering years of life lost as well as the number of attributable deaths. methods: the study population is classified in birth cohorts. for each cohort, 2 survival curves are built based on current mortality conditions: the first is built for current exposure to air pollution and the second for exposure to a lower reference level of air pollution. The area between the 2 curves represents years of life lost attributable to urban air pollution. results: the estimated number of premature deaths due to air pollution is approximately 56, or about 2% of the deaths of those older than 30 years. The health impact on the Nantes population is estimated at 27.2 years of life lost attributable to urban air pollution in 1999 and 2388.1 years of life lost for the 1999-2008 period. This amounts to a decrease of roughly 4 months in the life expectancy of those aged 30 years. Conclusion: This study, which also identifies and discusses relevant errors and uncertainty, confirmed that air pollution in Nantes has significant health effects and that chronic exposure plays an essential role in this impact. the number of years of life lost and the reduction in life expectancy provide new reasons to reject the assumption that health effects are limited to the premature deaths of terminally-ill people. the expected health gains in Nantes associated with reduced although still moderate air pollution levels are on the same scale as, and possibly better than, those found in 9 other French cities for similar air pollution decreases. (authors)

  9. Evaluation of sanitary impact of the urban air pollution. Avignon area impact at short and long term; Evaluation de l'impact sanitaire de la pollution atmospherique urbaine. Zone d'Avignon impact a court et long terme

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    An health impact assessment of air pollution based on the I.n.V.S. guidelines has been conducted in Avignon according to the Regional Plan for the quality of air in the region of Provence Alpes Cote d'Azur. Short term impact of atmospheric pollution has been estimated in term of mortality (total, cardiovascular and respiratory mortality) and hospital admissions (for respiratory, cardiovascular and cardiac reasons) attributable to air pollution. Long-term impact was also assessed by the number of deaths due to atmospheric pollution. The study has been carried out in seven cities homogeneously exposed belonging to Vaucluse (Avignon, Le Pontet, Morieres les Avignon, Sorgues and Vedene) and two cities of the Gard department (les Angles and Villeneuve les Avignon) representing a study population of 153,624 inhabitants. Two period of study have been defined: period 1999-2000 for short and long term evaluations on the mortality and the year 2001 for the morbidity analysis. This study rests on methodological principles of E.I.S. (evaluation of sanitary impact) of urban air pollution whom methodology is in four steps: identification of dangers, exposure estimation, choice of exposure-risk relationship and risk characterisation. The pollutions indicators are built from four pollutants nitrogen dioxide, ozone, sulfur dioxide and PM{sub 10}. The exposure-risk relationships used come from epidemiological studies realised in general population, by preferring the multi centers studies and European ones. The number of deaths by year due to air pollution is 23, whom 10 by cardiovascular diseases, 2 by respiratory diseases. The most efficient scenario are these ones corresponding to air pollution decreases of 25% in the considered pollutant. About the long term sanitary benefits, the different scenario show that the European norm forecasted for 2005 is respected. The respect of the European norm expected for 2010 should allow to avoid 10 deaths on the totality of registered deaths on a year, whereas a 25% decrease of the year average should allow to avoid 25 ones. According to the uncertainties and limits of the used methodology, the results must be interpreted as order of magnitude of the impact of air pollution on population health in the studied area. This study shows that even if the risks relative to air pollution are low, the proportion of exposed persons leads to a non negligible impact on mortality. It shows that sanitary effects appear at levels under that these ones actually measured and then the most efficient measures would be these ones that would associate a reduction of emissions at the source with an important reduction of the pollution peaks number. (N.C.)

  10. Epidemiological surveillance - air and health. Surveillance of effects on health linked to air pollution in urban area; Surveillance epidemiologique - air et sante. Surveillance des effets sur la sante lies a la pollution atmospherique en milieu urbain

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    In order to quantify the short term relationship between the air pollution and its effects on health and to monitor its evolution, the Institute of Sanitary Watch, with the help of the Department of development and environment and the Department in charge of health, has realised a study in eight towns: Bordeaux, Le Havre, Lille, Lyon, Marseille, Rouen, Strasbourg and Toulouse. These towns have been chosen for the contrasted character of their sources, of their pollution levels and their geo climatic conditions. Paris contributes to the study with the E.R.P.U.R.S results. (N.C.)

  11. Amenability of Muzret bituminous coal to oil agglomeration

    Energy Technology Data Exchange (ETDEWEB)

    Sahinoglu, E.; Uslu, T. [Karadeniz Technical University, Department of Mining Engineering, 61080 Trabzon (Turkey)

    2008-12-15

    Laboratory scale agglomeration tests were undertaken to investigate the amenability of Muzret (Yusufeli-Artvin) bituminous coal to oil agglomeration. Kerosene was extensively used as oil in the tests. In addition, fuel oil, diesel oil, and hazelnut oil were also used in order to determine the effect of oil type. The effects of the parameters including coal content, kerosene content, agglomeration time, coal particle size, pH, oil type, and agitation rate, on the combustible matter recovery, ash reduction and pyritic sulphur reduction, were investigated. It was found that Muzret bituminous coal could be readily cleaned by oil agglomeration with substantial reductions in ash and pyritic sulphur content. Maximum combustible matter recovery, ash reduction and pyritic sulphur reduction were achieved to be 85.54%, 59.98%, and 85.17%, respectively. (author)

  12. Assessment of mercury content in poplar leaves of Novokuznetsk agglomeration

    Science.gov (United States)

    Lyapina, E. E.; Yusupov, D. V.; Tursunalieva, E. M.; Osipova, V. V.

    2016-11-01

    In this paper, the content of mercury in poplar leaves in the Novokuznetsk industrial agglomeration and along the automobile route Novokuznetsk-Mezhdurechensk is assessed. The geoecological indicators are also calculated.

  13. Acoustic Agglomeration Process of Fine Particles in a Resonance Structure

    Science.gov (United States)

    Shi, Chen-hao; Zhang, Jian; Zhao, Yun; Liang, Jie

    2017-07-01

    It was proved that the acoustic agglomeration technology has a good application prospect in the removal of fine particles. In this paper, a removal system of acoustic agglomeration is constructed by the acoustic resonance structure. With the finite element simulation model, the effect and condition of sound pressure level (SPL) increment of high intensity sound in the resonance structure are defined. In the experiment, the contrast of the sampling weight and particle size distribution changes of fine particles was compared under different operating conditions to examine the effect of acoustic agglomeration on the removal efficiency of fine particles. The results show the SPL increment of 10dB is obtained with SPL 145-165 dB when the working frequency is changed from 400 to 2000 Hz. Under the action of acoustic agglomeration, fine particles in the aerosol were significantly reduced, and the removal effect is markedly improved with the increase of SPL.

  14. Simulation of atomic layer deposition on nanoparticle agglomerates

    NARCIS (Netherlands)

    Jin, W.; van Ommen, J.R.; Kleijn, C.R.

    2016-01-01

    Coated nanoparticles have many potential applications; production of large quantities is feasible by atomic layer deposition (ALD) on nanoparticles in a fluidized bed reactor. However, due to the cohesive interparticle forces, nanoparticles form large agglomerates, which influences the coating

  15. Contact mechanics of highly porous oxide nanoparticle agglomerates

    NARCIS (Netherlands)

    Fabre, A.; Salameh, S.; Colombi Ciacchi, Lucio; Kreutzer, M.T.; van Ommen, J.R.

    2016-01-01

    Efficient nanopowder processing requires knowledge of the powder’s mechanical properties. Due to the large surface area to volume ratio, nanoparticles experience relatively strong attractive interactions, leading to the formation of micron-size porous structures called agglomerates. Significant

  16. Émeutes urbaines, sentiments d’injustice, mobilisations associatives

    Directory of Open Access Journals (Sweden)

    Éric Marlière

    2011-07-01

    Full Text Available Cet article a pour objectif l’appréhension des répertoires de mobilisations politiques des jeunes dits « des cités ». Pour cela, il faut nous intéresser aux modes de vie de ces jeunes structurés depuis plus de trente ans maintenant autour du chômage et de la précarité et des nouvelles formes de ségrégation. Cette situation engendre chez les jeunes une certaine frustration sociale se manifestant sous la forme d’un sentiment d’injustice plus ou moins diffus. Si les émeutes urbaines constituent le mode d’action le plus médiatique, un certain nombre de jeunes adultes originaires « des cités » réagissent à travers un ensemble d’initiatives associatives nationales et locales comme le montrent les dernières échéances électorales.Urban riots, feeling of injustice and associative mobilizationsThis article’s objective are the understanding of the directories of the political youth called “cities”. For this, we must concern ourselves with life’s styles of the young people structured over 30 years now about unemployment and job insecurity and new forms of segregation. This creates youth frustration manifested as a feeling of injustice more or less diffuse. If the urban riots of action in the most media, a number of young adults from the “cities” are responding through a number of national associations and local initiatives as evidenced by the recent elections.Revueltas urbanas, sentimientos de injusticia, formas asociativasEste artículo tiene como objetivo el aprehender las diferentes formas de las movilizaciones políticas de los jóvenes de los barrios desfavorecidos. Para cumplirlo es necesario que nos interesemos por las maneras de vivir de esos jóvenes cuyas vidas se desarrollan dentro del paro, la precariedad y nuevas formas de segregación. Esta situación engendra una gran frustración social con conciencia más o menos difusa de ser víctimas de injusticias. Si las revueltas urbanas constituyen la

  17. L’horizon urbain dans la littérature de la surmodernité. Retrouver le paysage The urban horizon in postmodern literature

    Directory of Open Access Journals (Sweden)

    Laurent Mattille

    2009-10-01

    Full Text Available Notre époque, qualifiée parfois de surmoderne, voit l’environnement urbain évoluer sous la pression de plusieurs facteurs. Parmi ceux-ci, le développement débridé des périphéries et l’expansion anarchique de l’univers médiatique, ont des conséquences sur le paysage. L’observateur contemporain peine souvent à reconnaître des perspectives citadines cohérentes. Néanmoins, l’arpenteur de l’agglomération parisienne qu’est Jacques Réda, maintient dans Le Citadin la tradition paysagère urbaine. Dans Zones et La Clôture, Rolin, pour sa part, peint l’effet déstructurant et confiscatoire qu’opère le monde médiatique sur cette même ville de Paris. Il tente ainsi de nous montrer plusieurs aspects de la surmodernité telle qu’elle peut être vécue. Il s’accommode pourtant de cette surmodernité en se l’appropriant en quelques occasions propices à l’émergence d’environnements proprement paysagers.In our era, sometimes referred to as postmodern, urban environments have been evolving under pressure from several factors. Among these, the unbridled development of suburban areas and the anarchic expansion of the media both affect landscapes. Present-day observers often find no consistency within urban landscapes. Nonetheless, Jacques Réda, who thouroughly knows the Paris agglomeration, maintains in his book Le Citadin the existence of an urban landscape tradition. In Zones et La Clôture, Rolin describes the disorderly and confiscatory effect of the media on this same city of Paris. He thus attempts to show several aspects of postmodernity as it can be lived. He nevertheless makes the best of this postmodernity by making it his own on those occasions favorable to the emergence of properly landscape environments.

  18. The vacancies formation and agglomeration under centrifugal force

    Science.gov (United States)

    Wierzba, Bartek

    2017-10-01

    In this paper the vacancies formation and agglomeration under centrifugal force - sedimentation will be analyzed. The evolutionary algorithm for diffusion and vacancy evolution will be shown. The model predicts the location of vacancies agglomeration during the sedimentation process - the most probably place of voids formation. The computed results will be compared with experiments in Cu-brass diffusion couple. The influence of the centrifugal force on the vacancies migration will be presented.

  19. Aluminum Agglomeration and Trajectory in Solid Rocket Motors

    Science.gov (United States)

    2007-08-30

    agglomerates coming off the surface of a burning propellant. These methods include film studies 6, quench particles combustion bomb (QPCB) devices similar...34the stepwise oxidation of aluminum (that) is caused by the sequence of polymorphic phase transitions occurring in the growing oxide film ",2 5 . 25... cinematography data from China Lake. Task 2.2, Aluminum Agglomeration Model Selection (SEA/BYU/ATK Task) Part of the model selection task has already been

  20. Using Raster Based Solutions to Identify Spatial Economic Agglomerations

    Directory of Open Access Journals (Sweden)

    Marian DARDALA

    2013-01-01

    Full Text Available The efficient economic activities incline to be concentrated in space, and therefore there is an increased attention over the forces of spatial economic agglomerations and the role of location in economic development. This paper proposes some solutions to automate the identification of spatial agglomerations and their intensities, function on the spatial distribution of items in the geographical areas. The software components developed to accomplish this task are Geographic Information Systems specific tools.

  1. Acoustic agglomeration of power plant fly ash. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Reethof, G.; McDaniel, O.H.

    1982-01-01

    The work has shown that acoustic agglomeration at practical acoustic intensities and frequencies is technically and most likely economically viable. The following studies were performed with the listed results: The physics of acoustic agglomeration is complex particularly at the needed high acoustic intensities in the range of 150 to 160 dB and frequencies in the 2500 Hz range. The analytical model which we developed, although not including nonlinear acoustic efforts, agreed with the trends observed. We concentrated our efforts on clarifying the impact of high acoustic intensities on the generation of turbulence. Results from a special set of tests show that although some acoustically generated turbulence of sorts exists in the 150 to 170 dB range with acoustic streaming present, such turbulence will not be a significant factor in acoustic agglomeration compared to the dominant effect of the acoustic velocities at the fundamental frequency and its harmonics. Studies of the robustness of the agglomerated particles using the Anderson Mark III impactor as the source of the shear stresses on the particles show that the agglomerates should be able to withstand the rigors of flow through commercial cyclones without significant break-up. We designed and developed a 700/sup 0/F tubular agglomerator of 8'' internal diameter. The electrically heated system functioned well and provided very encouraging agglomeration results at acoustic levels in the 150 to 160 dB and 2000 to 3000 Hz ranges. We confirmed earlier results that an optimum frequency exists at about 2500 Hz and that larger dust loadings will give better results. Studies of the absorption of acoustic energy by various common gases as a function of temperature and humidity showed the need to pursue such an investigation for flue gas constituents in order to provide necessary data for the design of agglomerators. 65 references, 56 figures, 4 tables.

  2. Survival of the fittest in cities: agglomeration, selection, and polarisation

    OpenAIRE

    Kristian Behrens; Frédéric Robert-Nicoud

    2008-01-01

    Empirical studies consistently report that labour productivity and TFP rise with city size. The reason is that cities attract the most productive agents, select the best of them, and make the selected ones even more productive via various agglomeration economies. This paper provides a microeconomically founded model of vertical city differentiation in which the latter two mechanisms (`agglomeration' and `selection') operate simultaneously. Our model is both rich and tractable enough to allow ...

  3. Gestion décentralisée des déchets solides urbains en Indonésie ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    En Indonésie, les zones urbaines produisent 55 000 tonnes de déchets solides par jour, et on s'attend à ce que ce volume triple d'ici à 2025. On ne collecte que 50 à 60 % des déchets urbains qui se retrouvent, pour la plupart, dans des dépotoirs à ciel ouvert. Incapacité à recouvrer les coûts d'exploitation, absence de ...

  4. Stratégie de survie et culture de jeunes dans les marchés urbains ...

    African Journals Online (AJOL)

    Cet article porte sur la vie quotidienne des adolescentes travailleuses dans les marchés urbains et péri-urbains de Dakar, capitale du Sénégal. Elle vise à approfondir la compréhension et la connaissance sur les stratégies de survie et la socialisation des jeunes dans les rues des villes sénégalaises et sur les logiques de ...

  5. Outlines of the theory of urban agglomerations' self-development

    Directory of Open Access Journals (Sweden)

    Evgeniy Georgievich Animitsa

    2012-03-01

    Full Text Available This paper discusses new trends in urban centers in Russia. It is noted that the interest of scientists to the problem has increased as urban agglomerations were declared regional areas of priority development. The author gives different interpretations of the content of the concept of «urban agglomeration», which are formulated in the context of different scientific approaches and scientific schools. It is emphasized that the city agglomeration as a special form of reality can be studied in the coordinates of a systemic paradigm. The basic axiomatic features that allow identifying the metropolitan area as a complex system are presented and disclosed. The conclusion was made that a self-developing urban agglomeration is a special type of actively operating territorial unit in which the actors of the local community are able to mobilize local resources by themselves (and, in particular, the human capital to change the living environment. The paper emphasizes the need to regulate the development of urban agglomerations and gives examples of two basic models of urban agglomerations management.

  6. Novel Binders and Methods for Agglomeration of Ore

    Energy Technology Data Exchange (ETDEWEB)

    S. K. Kawatra; T. C. Eisele; J. A. Gurtler

    2004-03-31

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily. A primary example of this is copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process. As a result, operators of acidic heap-leach facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of other agglomeration applications, particularly advanced primary ironmaking.

  7. Agglomeration Control during Ultrasonic Crystallization of an Active Pharmaceutical Ingredient

    Directory of Open Access Journals (Sweden)

    Bjorn Gielen

    2017-02-01

    Full Text Available Application of ultrasound during crystallization can efficiently inhibit agglomeration. However, the mechanism is unclear and sonication is usually enabled throughout the entire process, which increases the energy demand. Additionally, improper operation results in significant crystal damage. Therefore, the present work addresses these issues by identifying the stage in which sonication impacts agglomeration without eroding the crystals. This study was performed using a commercially available API that showed a high tendency to agglomerate during seeded crystallization. The crystallization progress was monitored using process analytical tools (PAT, including focus beam reflectance measurements (FBRM to track to crystal size and number and Fourier transform infrared spectroscopy (FTIR to quantify the supersaturation level. These tools provided insight in the mechanism by which ultrasound inhibits agglomeration. A combination of improved micromixing, fast crystal formation which accelerates depletion of the supersaturation and a higher collision frequency prevent crystal cementation to occur. The use of ultrasound as a post-treatment can break some of the agglomerates, but resulted in fractured crystals. Alternatively, sonication during the initial seeding stage could assist in generating nuclei and prevent agglomeration, provided that ultrasound was enabled until complete desupersaturation at the seeding temperature. FTIR and FBRM can be used to determine this end point.

  8. NOVEL BINDERS AND METHODS FOR AGGLOMERATION OF ORE

    Energy Technology Data Exchange (ETDEWEB)

    S.K. Kawatra; T.C. Eisele; J.A. Gurtler; C.A. Hardison; K. Lewandowski

    2004-04-01

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily. Primary examples of this are copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process, and advanced ironmaking processes, where binders must function satisfactorily over an extraordinarily large range of temperatures (from room temperature up to over 1200 C). As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching and advanced primary ironmaking.

  9. NOVEL BINDERS AND METHODS FOR AGGLOMERATION OF ORE

    Energy Technology Data Exchange (ETDEWEB)

    S.K. Kawatra; T.C. Eisele; J.A. Gurtler; K. Lewandowski

    2005-04-01

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not breakdown during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily. Primary examples of this are copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process. As a result, operators of many facilities see large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching.

  10. Incipient Motion of Sand and Oil Agglomerates

    Science.gov (United States)

    Nelson, T. R.; Dalyander, S.; Jenkins, R. L., III; Penko, A.; Long, J.; Frank, D. P.; Braithwaite, E. F., III; Calantoni, J.

    2016-12-01

    Weathered oil mixed with sediment in the surf zone in the northern Gulf of Mexico after the 2010 Deepwater Horizon oil spill, forming large mats of sand and oil. Wave action fragmented the mats into sand and oil agglomerates (SOAs) with diameters of about 1 to 10 cm. These SOAs were transported by waves and currents along the Gulf Coast, and have been observed on beaches for years following the spill. SOAs are composed of 70%-95% sand by mass, with an approximate density of 2107 kg/m³. To measure the incipient motion of SOAs, experiments using artificial SOAs were conducted in the Small-Oscillatory Flow Tunnel at the U.S. Naval Research Laboratory under a range of hydrodynamic forcing. Spherical and ellipsoidal SOAs ranging in size from 0.5 to 10 cm were deployed on a fixed flat bed, a fixed rippled bed, and a movable sand bed. In the case of the movable sand bed, SOAs were placed both proud and partially buried. Motion was tracked with high-definition video and with inertial measurement units embedded in some of the SOAs. Shear stress and horizontal pressure gradients, estimated from velocity measurements made with a Nortek Vectrino Profiler, were compared with observed mobility to assess formulations for incipient motion. For SOAs smaller than 1 cm in diameter, incipient motion of spherical and ellipsoidal SOAs was consistent with predicted critical stress values. The measured shear stress at incipient motion of larger, spherical SOAs was lower than predicted, indicating an increased dependence on the horizontal pressure gradient. In contrast, the measured shear stress required to move ellipsoidal SOAs was higher than predicted, even compared to values modified for larger particles in mixed-grain riverine environments. The laboratory observations will be used to improve the prediction of incipient motion, transport, and seafloor interaction of SOAs.

  11. Novel Binders and Methods for Agglomeration of Ore

    Energy Technology Data Exchange (ETDEWEB)

    S. K. Kawatra; T. C. Eisele; K. A. Lewandowski; J. A. Gurtler

    2006-12-31

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily. Primary examples of this are copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process, and advanced ironmaking processes, where binders must function satisfactorily over an extraordinarily large range of temperatures (from room temperature up to over 1200 C). As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching and advanced primary ironmaking. This project has identified several acid-resistant binders and agglomeration procedures that can be used for improving the energy efficiency of heap leaching, by preventing the ''ponding'' and ''channeling'' effects that currently cause reduced recovery and extended leaching cycle times. Methods have also been developed for iron ore

  12. Réorganiser le développement urbain ?

    OpenAIRE

    Vauglin, François

    2016-01-01

    Formes et objectifs Dans les chapitres précédents, l’attention a été portée sur la production d’énergie, si possible renouvelable, et sur ses enjeux industriels, économiques, ou en termes de consommation. Mais on peut aussi poser la question du renouvelable en lien avec le développement urbain. Ceci concerne non seulement l’intégration de la production d’énergie renouvelable dans l’espace urbain, mais aussi (et surtout) la « production de non consommation d’énergie », car les économies d’éner...

  13. Réaffectation urbaine et développement socio-économique

    OpenAIRE

    Cornut, Pierre; Castiau, Etienne; Roelandts, Marcel; Van Criekingen, Mathieu

    2016-01-01

    Le site de Tour et Taxis, friche industrielle d’une trentaine d’ha située en plein centre de l’agglomération bruxelloise, fait l’objet d’un important projet de réaffectation qui s’inscrit dans un schéma devenu classique de politique de remodelage urbain. Les projets-phares ou « flagship projects », opérations de rénovation et de construction urbaines de grande ampleur, de haut standing et d’une visibilité qui se veut internationale, ont l’ambition de dynamiser l’image des villes occidentales ...

  14. Effect of magnetite nanoparticle agglomerates on ultrasound induced inertial cavitation.

    Science.gov (United States)

    Smith, Moira J; Ho, Vincent H B; Darton, Nicholas J; Slater, Nigel K H

    2009-06-01

    High intensity focused ultrasound (HIFU) induced inertial cavitation has been shown to improve release and cellular uptake of drugs. The effects of magnetite nanoparticle agglomerates (290+/-10nm diameter), silica coated magnetite nanoparticle agglomerates (320+/-10nm diameter) and silica particles (320+/-10nm diameter) suspended in MilliQ water on the degree of inertial cavitation due to HIFU were investigated. The HIFU transducer was operated at a frequency of 1.1 MHz, 1.67 kHz pulse repetition frequency, with applied duty cycles (DC) between 0% and 5% and different peak negative focal pressures (PNFPs) applied up to 7.2 MPa. The inertial cavitation dose (ICD: time averaged root-mean-squared broadband noise amplitude in the frequency domain) was measured in the presence and absence of nanoparticles when subjected to HIFU. Magnetite nanoparticle agglomerates caused a significant increase in the ICD above 2.7 MPa PNFP compared with MilliQ water, silica coated magnetite agglomerates and silica particles. With the dramatic increase in ICD on introduction of these magnetite agglomerates, this technique could provide a method of HIFU triggered drug delivery by enhancing inertial cavitation. The superparamagnetic properties of these particles offer the possibility of magnetic targeting to the site of disease.

  15. Theranostic potential of gold nanoparticle-protein agglomerates

    Science.gov (United States)

    Sanpui, Pallab; Paul, Anumita; Chattopadhyay, Arun

    2015-11-01

    Owing to the ever-increasing applications, glittered with astonishing success of gold nanoparticles (Au NPs) in biomedical research as diagnostic and therapeutic agents, the study of Au NP-protein interaction seems critical for maximizing their theranostic efficiency, and thus demands comprehensive understanding. The mutual interaction of Au NPs and proteins at physiological conditions may result in the aggregation of protein, which can ultimately lead to the formation of Au NP-protein agglomerates. In the present article, we try to appreciate the plausible steps involved in the Au NP-induced aggregation of proteins and also the importance of the proteins' three-dimensional structures in the process. The Au NP-protein agglomerates can potentially be exploited for efficient loading and subsequent release of various therapeutically important molecules, including anticancer drugs, with the unique opportunity of incorporating hydrophilic as well as hydrophobic drugs in the same nanocarrier system. Moreover, the Au NP-protein agglomerates can act as `self-diagnostic' systems, allowing investigation of the conformational state of the associated protein(s) as well as the protein-protein or protein-Au NP interaction within the agglomerates. Furthermore, the potential of these Au NP-protein agglomerates as a novel platform for multifunctional theranostic application along with exciting future-possibilities is highlighted here.

  16. Templated nucleation of acetaminophen on spherical excipient agglomerates.

    Science.gov (United States)

    Quon, Justin L; Chadwick, Keith; Wood, Geoffrey P F; Sheu, Iris; Brettmann, Blair K; Myerson, Allan S; Trout, Bernhardt L

    2013-03-12

    We investigated the effect of spherical agglomeration of heterogeneous crystalline substrates on the nucleation of acetaminophen (AAP). Optical and electron microscopy showed that the surface morphologies of single crystal triclinic lactose and D-mannitol differed significantly from their counterparts formed via spherical agglomeration. Spherical agglomerates of lactose were shown to enhance the nucleation rate of acetaminophen (AAP) by a factor of 11 compared to single crystal lactose; however, no such enhancement was observed for D-mannitol. X-ray powder diffraction identified the presence of new crystal faces of lactose present only in the spherical agglomerates However, D-mannitol did not show any significant change in crystal morphology. The new crystal faces of triclinic lactose were analyzed using geometric lattice matching software and molecular dynamics simulations to establish any new and significant epitaxial matches between lactose and AAP. A coincident lattice match and a large favorable energy interaction from hydrogen bonding were observed between the (141¯) and (001) crystal faces of lactose and AAP, respectively. The enhanced nucleation kinetics, X-ray data, and computational studies indicated that the spherical crystallization of lactose exposed the (141¯) face on the surface of the agglomerates, which subsequently enhanced the nucleation rate of AAP through geometric lattice matching and molecular functionality. This study highlights the importance of exploring different heterogeneous substrate morphologies for enhancing nucleation kinetics.

  17. Advanced physical fine coal cleaning spherical agglomeration. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1990-09-01

    The project included process development, engineering, construction, and operation of a 1/3 tph proof-of-concept (POC) spherical agglomeration test module. The POC tests demonstrated that physical cleaning of ultrafine coal by agglomeration using heptane can achieve: (1) Pyritic sulfur reductions beyond that possible with conventional coal cleaning methods; (2) coal ash contents below those which can be obtained by conventional coal cleaning methods at comparable energy recoveries; (3) energy recoveries of 80 percent or greater measured against the raw coal energy content; (4) complete recovery of the heptane bridging liquid from the agglomerates; and (5) production of agglomerates with 3/8-inch size and less than 30 percent moisture. Test results met or exceeded all of the program objectives. Nominal 3/8-inch size agglomerates with less than 20 percent moisture were produced. The clean coal ash content varied between 1.5 to 5.5 percent by weight (dry basis) depending on feed coal type. Ash reductions of the run-of-mine (ROM) coal were 77 to 83 percent. ROM pyritic sulfur reductions varied from 86 to 90 percent for the three test coals, equating to total sulfur reductions of 47 to 72 percent.

  18. 73 Utilisation du SIG pour une réorganisation urbaine du centre-ville ...

    African Journals Online (AJOL)

    TOHOZIN

    risques sont des lieux de prédilection des établissements de l'habitat informel. ... nouvelles voies et réorienter les nouveaux projets de reconstruction devient de plus en plus incontournable. Cette étude vise à ... municipalité et autres acteurs de développement urbains pour une gestion efficace de l'espace. Il s'agit de.

  19. 127 Impact des rejets urbains et industriels sur la qualité des eaux ...

    African Journals Online (AJOL)

    PR BOKO

    ISSN 1813-548X, http://www.afriquescience.info. Dj. KERBOUB et Ch. FEHDI. 127. Impact des rejets urbains et industriels sur la qualité des eaux souterraines : cas de la région d'El Kantar, Sud-Est Algérien. Dj. KERBOUB et Ch. FEHDI*. Department of Geology, Cheikh El Arbi Tébessi University, Tébessa 12002, Algeria ...

  20. Pratiques urbaines et imbroglio spatial : Brazzaville de la fin de la ...

    African Journals Online (AJOL)

    chifaou.amzat

    2 août 2011 ... par les propriétaires fonciers. Sollicitant les services des avocats dans les revendications des terrains, la rixe s'anime, dans une dimension maximaliste, entre pouvoirs publics et propriétaires fonciers10. Dans le but d'arrêter le recul spatial observé dans le périmètre urbain, depuis plus de deux décennies,.

  1. Initiative Villes ciblées : gestion des déchets urbains à Cochabamba ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Initiative Villes ciblées : gestion des déchets urbains à Cochabamba, en Bolivie ... Les services de gestion des déchets solides de Cochabamba sont inefficaces; les conditions d'exploitation du dépotoir entraînent une contamination de l'eau souterraine, de l'air et du sol ... Sociedad de Gestión Ambiental Boliviana S.R.L..

  2. Coopération entre milieux ruraux et urbains dans la gestion de l'eau ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Coopération entre milieux ruraux et urbains dans la gestion de l'eau face aux changements climatiques au Burkina Faso. Les villes dépendent fortement des milieux ruraux qui leur assurent un apport en produits alimentaires, en eau et en matières premières. Les changements climatiques, en augmentant la fréquence des ...

  3. Étude du dilemme urbain : urbanisation, pauvreté et violence | CRDI ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    24 mai 2012 ... Dans un premier temps, afin d'éclairer la conception et la portée de l'initiative de recherche Villes sûres et inclusives, le CRDI a commandé une étude intitulée Researching the Urban Dilemma: Urbanization, Poverty and Violence (Étude du dilemme urbain : urbanisation, pauvreté et violence), laquelle vise ...

  4. Interdépendance des zones urbaines et rurales et répercussions ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    La présente étude vise à comprendre l'interdépendance des zones rurales et urbaines au Malawi et en Tanzanie; à recenser les vulnérabilités et les stratégies d'adaptation des collectivités et à expliquer les répercussions des changements climatiques sur elles; et à proposer aux collectivités, aux gouvernements locaux ...

  5. Un meilleur aménagement urbain pourrait réduire la criminalité ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    19 oct. 2015 ... Dans leur énoncé de politique intitulé Prévention du crime et cohésion sociale des collectivités : Le cas du milieu urbain ghanéen [traduction], l'équipe de recherche recommande que les décideurs tiennent compte de l'interaction entre le milieu bâti et les aspects sociaux de la vie collective s'ils cherchent à ...

  6. La ville et la croissance urbaine dans l'espace-temps

    Directory of Open Access Journals (Sweden)

    Denise Pumain

    1999-09-01

    Full Text Available L'élévation historique de la vitesse des déplacements modifie les propriétés de l'espace dans lequel s'effectuent les interactions sociales. Le concept d'espace-temps permet de délimiter des objets géographiques comme les villes, d'une manière qui soit comparable d'une période à une autre en termes de durées de parcours et donc de possibilités d'interactions, ce qui se traduit par une expansion urbaine dans l'espace mesuré en kilomètres. Une expérience menée sur le cas de Valence montre une certaine coïncidence entre la zone d'accessibilité de trente minutes et l'espace couvert par la croissance urbaine et péri-urbaine, depuis le début du xixe siècle.

  7. Agglomeration processes in carbonaceous dusty plasmas, experiments and numerical simulations

    Energy Technology Data Exchange (ETDEWEB)

    Dap, S; Hugon, R; De Poucques, L; Bougdira, J [Nancy Universite-Institut Jean Lamour, Dpt CP2S UMR 7198 CNRS, Faculte des Sciences et Technologies, BP 70239, 54506 Vandoeuvre-les-Nancy cedex (France); Lacroix, D [Nancy Universite-LEMTA, UMR 7563 CNRS, Faculte des Sciences et Technologies, BP 70239, 54506 Vandoeuvre-les-Nancy cedex (France); Patisson, F, E-mail: david.lacroix@lemta.uhp-nancy.f [Nancy Universite-Institut Jean Lamour, Dpt SI2M UMR 7198 CNRS, Ecole des Mines de Nancy, Parc de Saurupt-CS 14234, 54042 Nancy cedex (France)

    2010-09-15

    This paper deals with carbon dust agglomeration in radio frequency acetylene/argon plasma. Two studies, an experimental and a numerical one, were carried out to model dust formation mechanisms. Firstly, in situ transmission spectroscopy of dust clouds in the visible range was performed in order to observe the main features of the agglomeration process of the produced carbonaceous dust. Secondly, numerical simulation tools dedicated to understanding the achieved experiments were developed. A first model was used for the discretization of the continuous population balance equations that characterize the dust agglomeration process. The second model is based on a Monte Carlo ray-tracing code coupled to a Mie theory calculation of dust absorption and scattering parameters. These two simulation tools were used together in order to numerically predict the light transmissivity through a dusty plasma and make comparisons with experiments.

  8. Recent demographic-economic processes in the Belgrade agglomeration

    Directory of Open Access Journals (Sweden)

    Vojković Gordana

    2010-01-01

    Full Text Available In this paper, basic characteristics of demographic and economic changes in the area of Belgrade agglomeration in the second half of 20th century has been researched, and a global trend of their establishments and motions has been indicated. Changes of territorial arrangement, spatial distribution and structural features of population, within the agglomeration itself, were in close interaction with directions of development and expansion of urban region. Belgrade agglomeration development follows several stages in its physiognomic-spatial, economic and demographic growth, whereby the migrations, as in cases of all large urban systems, had special influence on growth and structural features of population. In this paper, modern development processes and their effects on demographic growth have been emphasized. .

  9. A stochastic pocket model for aluminum agglomeration in solid propellants

    Energy Technology Data Exchange (ETDEWEB)

    Gallier, Stany [SNPE Materiaux Energetiques, Vert le Petit (France)

    2009-04-15

    A new model is derived to estimate the size and fraction of aluminum agglomerates at the surface of a burning propellant. The basic idea relies on well-known pocket models in which aluminum is supposed to aggregate and melt within pocket volumes imposed by largest oxidizer particles. The proposed model essentially relaxes simple assumptions of previous pocket models on propellant structure by accounting for an actual microstructure obtained by packing. The use of statistical tools from stochastic geometry enables to determine a statistical pocket size volume and hence agglomerate diameter and agglomeration fraction. Application to several AP/Al propellants gives encouraging results that are shown to be superior to former pocket models. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  10. THE SPATIAL AGGLOMERATION OF EDUCATED PEOPLE IN COLOMBIA

    Directory of Open Access Journals (Sweden)

    Juan Tomás Sayago Gómez

    2014-01-01

    Full Text Available Over the past few decades, Colombia's education system has been growing in terms of access and coverage. However, this development has taken place mainly in bigger cities, and displays an agglomeration of graduates in tertiary education. The purpose of this article is to test this hypothesis of agglomeration and attempt to find out which factors are associated to this phenomena: quality of life, the effects of income, political safety, and supply of education. Using empirical evidence derived from real data obtained by DANE in the 2005 Census and a variable of violence from the IEPRI, spatial econometric models are set out to understand its dynamics, to stop and reverse this agglomeration, and to create benefits for smaller municipalities.

  11. Stone Dust Agglomeration for Utilizing as Building Material

    Directory of Open Access Journals (Sweden)

    Gabriel Borowski

    2017-12-01

    Full Text Available In the paper we discuss the possibility of using stone dust for utilizing as building material. The tested material was amphibolite, found in the Sudeten Mountains and the Tatra Mountains in Poland. The chemical composition of dust was determined by means of spectrometry methods. Moreover, the basic physical properties of the material were designated. Stone dust was mixed with starch or cement binder. The binder addition was from 5% to 20% by weight. The water content was adjusted to about 25% humidity. The mixture was then compressed in a hydraulic press at 50 MPa. The results of the mechanical toughness of agglomerates were shown. On the basis of the results, acceptable toughness of agglomerates was found, with the addition of cement in mass share 20% and seasoning for 48 hours. However, starch was not suitable as a binder for agglomeration of amphibolite.

  12. Basic principles and mechanisms of selective oil agglomeration

    Energy Technology Data Exchange (ETDEWEB)

    Wheelock, T.D.; Drzymala, J.; Allen, R.W.; Hu, Y.-C.; Tyson, D.; Xiaoping, Qiu; Lessa, A.

    1990-01-01

    Numerous measurements of the heat of immersion of coal were conducting using several different particle size fractions of No. 2 Gas Seam coal from Raleigh County, West Virginia. The heat of immersion was determined in water, methanol, heptane, hexadecane and neohexane (2,2-dimethybutane). A comparison of the results with those determined previously for Illinois No. 6 coal is discussed. A number of potential pyrite depressants for use in oil agglomeration of coal were screened by testing the response of sulfidized mineral pyrite to agglomeration with heptane in the presence of the potential depressant. The following were tested; sodium dithionite, sodium thiosulfate, ferrous sulfate, ferric sulfate, titanous chloride, hydrogen peroxide, Oxone (a form of potassium monopersulfate), pyrogallol, quebracho (colloidal dispersant derived from tree bark), milk whey, and several organic thiols. Ferric chloride was applied to mixtures of Upper Freeport coal and sulfidized mineral pyrite before subjecting the mixtures to agglomeration with heptane. 7 refs., 23 figs., 3 tabs.

  13. The Physics of Protoplanetesimal Dust Agglomerates. VIII. Microgravity Collisions between Porous SiO_2 Aggregates and Loosely Bound Agglomerates

    Science.gov (United States)

    Whizin, Akbar D.; Blum, Jürgen; Colwell, Joshua E.

    2017-02-01

    We performed laboratory experiments colliding 0.8-1.0 mm and 1.0-1.6 mm SiO2 dust aggregates with loosely bound centimeter-sized agglomerates of those aggregates in microgravity. This work builds on previous microgravity laboratory experiments examining the collisional properties of porous loosely bound dust aggregates. In centimeter-sized aggregates, surface forces dominate self-gravity and may play a large role in aggregate growth beyond this size range. We characterize the properties of protoplanetary aggregate analogs to help place constraints on initial formation mechanisms and environments. We determined several important physical characteristics of these aggregates in a large number of low-velocity collisions. We observed low coefficients of restitution and fragmentation thresholds near 1 m s-1 for 1-2 cm agglomerates, which are in good agreement with previous findings in the literature. We find the accretion efficiency for agglomerates of loosely bound aggregates to be higher than that for just aggregates themselves. We find sticking thresholds of 6.6 ± 2 cm s-1, somewhat higher than those in similar studies, which have observed few aggregates stick at speeds of under 3 cm s-1. Even with highly dissipative collisions, loosely bound agglomerates have difficulty accreting beyond centimeter-sized bodies at typical collision speeds in the disk. Our results indicate agglomerates of porous aggregates have slightly higher sticking thresholds than previously thought, allowing possible growth to decimeter-sized bodies if velocities are low enough.

  14. Basic principles and mechanisms of selective oil agglomeration

    Energy Technology Data Exchange (ETDEWEB)

    Wheelock, T.D.

    1994-07-01

    The overall objective of this work is to determine the important principles and basic mechanisms which underlie various selective oil agglomeration processes for beneficiating fine-size coal in order to facilitate the technical development and application of such processes to various types of coal. The recent work described herein has involved a more detailed study of the effects of mild oxidation on the surface properties of different types of coal and the relationship between the agglomerability of oxidized coals and their surface properties. In addition, the work has involved developing more effective means for separating coal and pyrite by finding and applying selective depressants for pyrite.

  15. Ice slurry cooling research: Storage tank ice agglomeration and extraction

    Energy Technology Data Exchange (ETDEWEB)

    Kasza, K. [Argonne National Lab., IL (United States); Hayashi, Kanetoshi [NKK Corp., Kawasaki (Japan)

    1999-08-01

    A new facility has been built to conduct research and development on important issues related to implementing ice slurry cooling technology. Ongoing studies are generating important information on the factors that influence ice particle agglomeration in ice slurry storage tanks. The studies are also addressing the development of methods to minimize and monitor agglomeration and improve the efficiency and controllability of tank extraction of slurry for distribution to cooling loads. These engineering issues impede the utilization of the ice slurry cooling concept that has been under development by various groups.

  16. Engagement militant et politisation des mobilisations au sein des oppositions urbaines à Istanbul

    Directory of Open Access Journals (Sweden)

    Clémence Petit

    2011-07-01

    Full Text Available La Municipalité du Grand Istanbul met en œuvre depuis quelques années une « politique de transformation urbaine » pour faire d’Istanbul une ville moderne et compétitive sur la scène mondiale. Les mobilisations locales et les mouvements protestataires se multiplient pour infléchir une politique qui domine aujourd’hui l’agenda urbain « néolibéral » et empêcher les démolitions et déplacements de population escomptés. Au-delà de la distance au politique généralement affichée – condition de légitimité dans le système sécuritaire mis en place en Turquie après le coup d’État de 1980 – ces « oppositions urbaines » sont traversées par des débats sur la place du politique dans la mobilisation. À partir de l’étude sociologique de deux associations de quartiers et de deux mouvements de « professionnels urbains », cette contribution analyse le travail de définition des cadrages et répertoires d’action propres à chaque mouvement. Elle fait apparaître le rôle de ces professionnels urbains dans la requalification politique du désaccord qui divise les oppositions urbaines entre une stratégie « experte » et une stratégie plus politique. L’analyse met néanmoins en évidence le caractère dynamique et relatif – en termes de contextes et d’échelles – des stratégies d’appropriation des politiques publiques locales et des processus de politisation des « mouvements urbains ».The Istanbul Greater Municipality has been implementing for a few years numerous ‘urban renewal projects’ to change Istanbul into a modern and competitive city on the global scene. Reacting to the demolitions and evictions of entire neighbourhoods caused by these projects, some inhabitants and ‘urban professionals’ mobilize within new movements and neighbourdhood associations. Beyond the distance they usually show towards politics – a condition of legitimacy in the securitarian system introduced in

  17. Sprawl urbano em Londrina e os desafios para o planejamento urbano Sprawl urbain à Londrina et ses défis pour la planification urbaine

    Directory of Open Access Journals (Sweden)

    Osvaldo Coelho Pereira Neto

    2011-07-01

    Full Text Available A urbanização dispersa, os instrumentos de planejamento e gestão urbanos como o zoneamento e as zonas de expansão urbana têm se mostrado cada vez mais coerentes ao direcionar as cidades para um futuro incerto e caótico. Os perímetros urbanos dos municípios têm sido utilizados cada vez mais em favor dos agentes reprodutores do espaço urbano desigual acirrando o processo de segregação sócio-espacial, a formação de vazios urbanos e a especulação imobiliária. Inerente a esse processo, a infraestrutura, um dos componentes mais importantes da terra urbana e que mais custam para o Poder Público, ficam cada vez mais dispersos e obsoletos no meio de uma ocupação desordenada do solo da cidade. A partir disso, este trabalho propõe analisar o fenômeno do sprawling urbano na cidade de Londrina através das geotecnologias e identificar quais os impactos que a forma de ocupação que a cidade tem se guiado podem provocar no cenário atual e futuro do município na sua totalidade. Para tanto, foram confeccionados mapas temáticos de múltiplas fontes e através da bibliografia pesquisada identificou-se que o município de Londrina possui intensas características do fenômeno sprawling trazendo conseqüências para o ordenamento territorial e a distribuição espacial igualitária dos serviços essenciais a população.L'étalement urbain, les instruments de planification et de gestion urbaine comme le zonage et le zonage de l’expansion urbaine semblent mener les villes vers un futur incertain et chaotique. Les périmètres d’urbanisation des municipalités sont de plus en plus utilisés en faveur des agents producteurs d’un espace urbain inéquitable, accentuant le processus de ségrégation socio-spatiale, le maintien de terrains vacants et la spéculation foncière. Conséquemment, les réseaux d’infrastructure, composantes urbaines essentielles qui constituent une des plus importantes sources de dépenses publiques, s

  18. Quantitative characterization of nanoparticle agglomeration within biological media

    Science.gov (United States)

    Hondow, Nicole; Brydson, Rik; Wang, Peiyi; Holton, Mark D.; Brown, M. Rowan; Rees, Paul; Summers, Huw D.; Brown, Andy

    2012-07-01

    Quantitative analysis of nanoparticle dispersion state within biological media is essential to understanding cellular uptake and the roles of diffusion, sedimentation, and endocytosis in determining nanoparticle dose. The dispersion of polymer-coated CdTe/ZnS quantum dots in water and cell growth medium with and without fetal bovine serum was analyzed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. Characterization by TEM of samples prepared by plunge freezing the blotted solutions into liquid ethane was sensitive to the dispersion state of the quantum dots and enabled measurement of agglomerate size distributions even in the presence of serum proteins where DLS failed. In addition, TEM showed a reduced packing fraction of quantum dots per agglomerate when dispersed in biological media and serum compared to just water, highlighting the effect of interactions between the media, serum proteins, and the quantum dots. The identification of a heterogeneous distribution of quantum dots and quantum dot agglomerates in cell growth medium and serum by TEM will enable correlation with the previously reported optical metrology of in vitro cellular uptake of this quantum dot dispersion. In this paper, we present a comparative study of TEM and DLS and show that plunge-freeze TEM provides a robust assessment of nanoparticle agglomeration state.

  19. Quantitative characterization of nanoparticle agglomeration within biological media

    Energy Technology Data Exchange (ETDEWEB)

    Hondow, Nicole, E-mail: n.hondow@leeds.ac.uk; Brydson, Rik [University of Leeds, Institute for Materials Research (United Kingdom); Wang, Peiyi [University of Leeds, Institute of Molecular and Cellular Biology (United Kingdom); Holton, Mark D.; Brown, M. Rowan; Rees, Paul; Summers, Huw D. [Swansea University, Centre for Nanohealth, College of Engineering (United Kingdom); Brown, Andy [University of Leeds, Institute for Materials Research (United Kingdom)

    2012-07-15

    Quantitative analysis of nanoparticle dispersion state within biological media is essential to understanding cellular uptake and the roles of diffusion, sedimentation, and endocytosis in determining nanoparticle dose. The dispersion of polymer-coated CdTe/ZnS quantum dots in water and cell growth medium with and without fetal bovine serum was analyzed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. Characterization by TEM of samples prepared by plunge freezing the blotted solutions into liquid ethane was sensitive to the dispersion state of the quantum dots and enabled measurement of agglomerate size distributions even in the presence of serum proteins where DLS failed. In addition, TEM showed a reduced packing fraction of quantum dots per agglomerate when dispersed in biological media and serum compared to just water, highlighting the effect of interactions between the media, serum proteins, and the quantum dots. The identification of a heterogeneous distribution of quantum dots and quantum dot agglomerates in cell growth medium and serum by TEM will enable correlation with the previously reported optical metrology of in vitro cellular uptake of this quantum dot dispersion. In this paper, we present a comparative study of TEM and DLS and show that plunge-freeze TEM provides a robust assessment of nanoparticle agglomeration state.

  20. Universities' Entrepreneurial Performance: The Role of Agglomeration Economies

    Science.gov (United States)

    Chen, Ping Penny

    2011-01-01

    In spite of the extensive research on universities' entrepreneurship, whether research strength fosters or dampens their entrepreneurial performance remains controversial. Much research claims an influential role of research universities in regional economy, however, little has been said about what a part that the agglomeration economies may play…

  1. Investigation on pore structure and small-scale agglomeration ...

    Indian Academy of Sciences (India)

    tives results in the modification in the pore size distribution and to some extent the total porosity. SANS revealed a ... agglomeration behaviour of the primary particles also affects the microstructure and the density of the .... estimated parameters from the fit of the model to the data are tabulated in table 1. The estimated pore ...

  2. Employment from new firm formation in the Netherlands: Agglomeration

    NARCIS (Netherlands)

    Knoben, J.; Ponds, R.H.F.; Oort, F.G. van

    2011-01-01

    Within the recent literature on the geography of new firm formation, much attention is given to the role of regional knowledge sources based on the Knowledge Spillover Theory of Entrepreneurship. At the same time, several other studies show the importance of agglomeration economies for new firm

  3. Investigation on pore structure and small-scale agglomeration ...

    Indian Academy of Sciences (India)

    Mesoscopic density fluctuations in liquid phase sintered silicon carbide have been investigated using small angle neutron scattering (SANS). The increase in the additives results in the modification in the pore size distribution and to some extent the total porosity. SANS revealed a mass fractal nature of the agglomerated ...

  4. Spherical agglomerates of lactose with enhanced mechanical properties.

    Science.gov (United States)

    Lamešić, Dejan; Planinšek, Odon; Lavrič, Zoran; Ilić, Ilija

    2017-01-10

    The aim of this study was to prepare spherical agglomerates of lactose and to evaluate their physicochemical properties, flow properties, particle friability and compaction properties, and to compare them to commercially available types of lactose for direct compression (spray-dried, granulated and anhydrous β-lactose). Porous spherical agglomerates of α-lactose monohydrate with radially arranged prism-like primary particles were prepared exhibiting a high specific surface area. All types of lactose analysed had passable or better flow properties, except for anhydrous β-lactose, which had poor flowability. Particle friability was more pronounced in larger granulated lactose particles; however, particle structure was retained in all samples analysed. The mechanical properties of spherical agglomerates of lactose, in terms of compressibility, established with Walker analysis, and compactibility, established with a compactibility profile, were found to be superior to any commercially available types of lactose. Higher compactibility of spherical agglomerates of lactose is ascribed to significantly higher particle surface area due to a unique internal structure with higher susceptibility to fragmentation. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Formation of the economic efficiency of industrial Dnipropetrovsk and Dniprodzerzhynsk agglomeration. O. V. Gladkyj

    Directory of Open Access Journals (Sweden)

    Gladkyj O.V.

    2009-08-01

    Full Text Available The features are opened of the formation of polycentric economic efficiency of industrial agglomerations. An assessment of the effectiveness of industrial Dnipropetrovsk Dneprodzerzhinskoy agglomeration and recommendations on optimization of its functional structure.

  6. Literature review and binder and coal selection for research studies on coal agglomeration

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, S.G.; Kuby, O.A.; Girimont, J.A.; peterson, C.A.; Saller, E.

    1982-02-26

    This report discusses the results of a literature survey on coal agglomeration and the approaches that were employed in selecting binders and coals to be studied in a process development program currently being performed for the Department of Energy. The survey is the first step toward the development of a useful process for the agglomeration of coal fines for use in a fixed-bed gasifier. Literature was found and reviewed on the effects of coal composition and physical properties, on agglomeration techniques and operating variables, on binders or additives to promote agglomeration, on pretreatment techniques on agglomerate feedstocks and post-treatment techniques on formed agglomerates, and on test results obtained by researchers in the past using various additives, treatments and agglomeration techniques. Much of this information did not deal directly with agglomerates for fixed-bed gasifiers, but the reported observations and results could be extrapolated to give useful guidelines for research plans. Conclusions and plans for further work are presented.

  7. Comments on an Analytical Thermal Agglomeration for Problems with Surface Growth

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, N. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-03-22

    Up until Dec 2016, the thermal agglomeration was very heuristic, and as such, difficult to define. The lack of predictability became problematic, and the current notes represent the first real attempt to systematize the specification of the agglomerated process parameters.

  8. La pédosphère urbaine : le sol de Paris XVIIIe-XXe siècles

    OpenAIRE

    Barles, Sabine

    1993-01-01

    Ce travail traite d'une partie souvent oubliée de la ville, le sous-sol peu profond qui accueille les réseaux, les racines de la végétation, les déchets urbains, à travers le cas français, parisien en particulier. Dans une première partie, on met en exergue les dysfonctionnements actuels de la pédosphère urbaine : dégradations des réseaux, de la végétation, perturbation des nappes, etc. Dans la seconde partie, on recherche les racines historiques de la perte de connaissance sur le sol urbain ...

  9. Phosphate-enhanced cytotoxicity of zinc oxide nanoparticles and agglomerates.

    Science.gov (United States)

    Everett, W Neil; Chern, Christina; Sun, Dazhi; McMahon, Rebecca E; Zhang, Xi; Chen, Wei-Jung A; Hahn, Mariah S; Sue, H-J

    2014-02-10

    Zinc oxide (ZnO) nanoparticles (NPs) have been found to readily react with phosphate ions to form zinc phosphate (Zn3(PO4)2) crystallites. Because phosphates are ubiquitous in physiological fluids as well as waste water streams, it is important to examine the potential effects that the formation of Zn3(PO4)2 crystallites may have on cell viability. Thus, the cytotoxic response of NIH/3T3 fibroblast cells was assessed following 24h of exposure to ZnO NPs suspended in media with and without the standard phosphate salt supplement. Both particle dosage and size have been shown to impact the cytotoxic effects of ZnO NPs, so doses ranging from 5 to 50 μg/mL were examined and agglomerate size effects were investigated by using the bioinert amphiphilic polymer polyvinylpyrrolidone (PVP) to generate water-soluble ZnO ranging from individually dispersed 4 nm NPs up to micron-sized agglomerates. Cell metabolic activity measures indicated that the presence of phosphate in the suspension media can led to significantly reduced cell viability at all agglomerate sizes and at lower ZnO dosages. In addition, a reduction in cell viability was observed when agglomerate size was decreased, but only in the phosphate-containing media. These metabolic activity results were reflected in separate measures of cell death via the lactate dehydrogenase assay. Our results suggest that, while higher doses of water-soluble ZnO NPs are cytotoxic, the presence of phosphates in the surrounding fluid can lead to significantly elevated levels of cell death at lower ZnO NP doses. Moreover, the extent of this death can potentially be modulated or offset by tuning the agglomerate size. These findings underscore the importance of understanding how nanoscale materials can interact with the components of surrounding fluids so that potential adverse effects of such interactions can be controlled. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  10. Spherical crystallization: direct spherical agglomeration of salicylic Acid crystals during crystallization.

    Science.gov (United States)

    Kawashima, Y; Okumura, M; Takenaka, H

    1982-06-04

    Direct spherical agglomeration of salicylic acid crystals during crystallization is described. The needle-like salicylic acid crystals simultaneously form and agglomerate in a mixture of three partially miscible liquids, such as water, ethanol, and chloroform, with agitation. The agglomerates can be made directly into tablets because of their excellent flowability. Spherical crystallization could eliminate the usual separate agglomeration step after crystallization and may be adaptable to other pharmaceutical and chemical systems.

  11. Water migration mechanisms in amorphous powder material and related agglomeration propensity

    NARCIS (Netherlands)

    Renzetti, S.; Voogt, J.A.; Oliver, L.; Meinders, M.B.J.

    2012-01-01

    The agglomeration phenomenon of amorphous particulate material is a major problem in the food industry. Currently, the glass transition temperature (Tg) is used as a fundamental parameter to describe and control agglomeration. Models are available that describe the kinetics of the agglomeration

  12. Rencontres urbaines : les leçons de Dar Es-Salaam, Port Louis et Saint-Denis

    OpenAIRE

    Cauna, Alexandra De; Roy, Cécile

    2008-01-01

    Historiquement marquées par l’échange, Port Louis (île Maurice), Saint-Denis (Réunion) et Dar es-Salaam (Tanzanie) sont des villes de la rencontre. Au delà de l’intérêt qu’une analyse sur les similitudes apporterait (ex-villes coloniales, espaces portuaires, capitales de l’océan Indien…), une mise en perspective des différents aspects des contacts intra-urbains semble intéressante. Elle seule peut mettre à jour la complexité des processus à l’œuvre. Dar es-Salaam, produit de rencontres urbain...

  13. Futebol et hiérarchies urbaines au Brésil.

    Directory of Open Access Journals (Sweden)

    Hervé Théry

    2006-03-01

    Full Text Available Le football n’est pas seulement la passion nationale du Brésil, il peut être aussi un bon indicateur des hiérarchies urbaines du pays. Les classements disponibles sur le site de la fédération brésilienne de futebol peuvent être mis en rapport avec d’autres données pour vérifier la corrélation entre les performances sportives des clubs et le degré de centralité des villes où ils sont basés.

  14. Cités horticoles en sursis ? L'agriculture urbaine dans les grandes ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Face à la crise des systèmes de production agricole ruraux, l'agriculture urbaine, notamment l'horticulture et l'élevage, est devenue une activité en pleine expansion. Ce secteur absorbe une partie de l'exode rural, contribue au développement d'activités génératrices de revenus et bénéficie d'une situation privilégiée grâce ...

  15. Urban Operations in the Year 2020 (Operations en zone urbaine en l’an 2020)

    Science.gov (United States)

    2003-04-01

    actuellement disponibles pour des opérations en zone urbaine sont essentiellement ceux de la deuxième guerre mondiale et se caractérisent par des...robotisés, les opérations de guerre électronique, etc. • favoriser l’interopérabilité. 8. Recommandations principales Le Groupe d’étude fait les...were required to isolate Grozny during the second Chechen campaign) and this sort of concept may not be feasible with large, sprawling urban areas

  16. Le droit, réponse aux incertitudes des problématiques urbaines ?

    OpenAIRE

    Alexandre Coque

    2007-01-01

    Face aux incertitudes, liées aux évolutions des problématiques urbaines, les différents acteurs sont amenés à replacer la norme juridique au centre de leurs interventions afin de rétablir une situation de stabilité et de confiance. Le droit au sens large du terme — loi, contrat, syndic de copropriété, règlement du lotissement… — apporterait donc les moyens de l’adaptation à l’incertitude vécue. Cet ouvrage, rédigé par sept auteurs, sociologues et urbanistes, regroupe ......

  17. 116 Avifaune urbaine de Cotonou et sa distribution en relation avec ...

    African Journals Online (AJOL)

    AKA BOKO

    L'avifaune urbaine de Cotonou a été recensée dans 24 stations représentatives de la gamme d'urbanisation et réparties du centre à la périphérie de la capitale économique du Bénin. 122 relevés sont effectués dans chacune des stations au moyen des points d'écoute de 10 minutes et de rayon 100 m. 115 espèces d' ...

  18. Une représentation symbolique de communication urbaine: le graffiti

    Directory of Open Access Journals (Sweden)

    Luciano Spinelli

    2008-07-01

    Full Text Available Nous avons l’intention d’observer une lecture sémiologique de l’espace urbain à travers l’étude des graffitis qui servent ici, d’analogie à la subjectivation que le citadin fait de son espace du vécu quotidien. Leurs graffitis sont intégrés à d’autres signes proposés par l’État et par l’initiative privée qui composent ainsi l’apparence loquace de la ville polyphonique.

  19. L’expansion urbaine et le grand commerce à La Réunion

    Directory of Open Access Journals (Sweden)

    Joël Ninon

    2000-09-01

    Full Text Available Dès le début des années 1980, la diffusion de la croissance urbaine se traduit à la Réunion par un phénomène de périurbanisation, affectant les espaces ruraux. Dans certains quartiers périurbains, ce processus s’accompagne de l’implantation de centres commerciaux. Ces structures deviennent souvent des pôles de développement à partir desquels se créent ou se renforcent des zones d’activités économiques, comme le montre l’exemple de Saint-Paul.

  20. Mathematical modeling of pigment dispersion taking into account the full agglomerate particle size distribution

    DEFF Research Database (Denmark)

    Kiil, Søren

    2017-01-01

    The purpose of this work is to develop a mathematical model that can quantify the dispersion of pigments, with a focus on the mechanical breakage of pigment agglomerates. The underlying physical mechanism was assumed to be surface erosion of spherical pigment agglomerates. The full agglomerate....... The only adjustable parameter used was an apparent rate constant for the linear agglomerate erosion rate. Model simulations, at selected values of time, for the full agglomerate particle size distribution were in good qualitative agreement with the measured values. A quantitative match of the experimental...

  1. Quantitative analysis of pigment dispersion taking into account the full agglomerate size distribution

    DEFF Research Database (Denmark)

    Kiil, Søren

    distribution was simulated. Data from previous experimental investigations with organic pigments were used for model validation.When the linear rate of agglomerate surface erosion was taken to be proportional to the external agglomerate surface area, simulations of the volume-moment mean diameter over time......This work concerns the development of simulation tools for mapping of pigment dispersion. Focus has been on the mechanical breakage of pigment agglomerates. The underlying physical mechanism was assumed to be surface erosion of spherical pigment agglomerates, and the full agglomerate particle size...... with measured values. The general applicability of the model, beyond the pigments considered, needs to be confirmed....

  2. The impact of agglomeration economies on hospital input prices.

    Science.gov (United States)

    Friedson, Andrew I; Li, Jing

    2015-12-01

    This paper examines the extent to which agglomeration of the hospital service industry enhances the productivity of producing health care. Specifically, we use a large set of private insurance claims from the FAIR Health database to show that an increasing spatial concentration of hospital services results in a decreased cost of obtaining intermediate medical services. We explicitly test whether the reduced cost at concentrated locations arises from the ability to share intermediate service providers. The identification relies on state variation in medical lab technician licensure requirements, which influence the cost of intermediate services only through the cost of running a lab. Our findings suggest that agglomeration of the hospital service industry attracts specialized medical labs, which in turn help to reduce the cost of producing laboratory tests.

  3. Preventing ash agglomeration during gasification of high-sodium lignite

    Energy Technology Data Exchange (ETDEWEB)

    Robert S. Dahlin; Johnny R. Dorminey; WanWang Peng; Roxann F. Leonard; Pannalal Vimalchand [Southern Research Institute and Southern Company Services, Wilsonville, AL (USA). Power Systems Development Facility

    2009-01-15

    Various additives were evaluated to assess their ability to prevent ash agglomeration during the gasification of high-sodium lignite. Additives that showed promise in simple muffle furnace tests included meta-kaolin, vermiculite, two types of silica fume, and one type of bauxite. Additives that were tested and rejected included dolomite, calcite, sand flour, kaolinite, fine kaolin, and calcined bauxite. Based on the muffle furnace test results, the meta-kaolin was selected for a follow-on demonstration in a pilot-scale coal gasifier. Pilot-scale testing showed that the addition of coarse (minus 14-mesh, 920-{mu}m mean size) meta-kaolin at a feed rate roughly equivalent to the ash content of the lignite (10 wt %) successfully prevented agglomeration and deposition problems during gasification of high-sodium lignite at a maximum operating temperature of 927{sup o}C (1700{sup o}F). 13 refs., 24 figs., 1 tab.

  4. Effect of agglomeration of silver nanoparticle on nanotoxicity depression

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Eunjoo; Yi, Jongheop [Seoul National University, Seoul (Korea, Republic of); Lee, Byung-Cheun; Choi, Kyunghee [National Institute of Environmental Research, Incheon (Korea, Republic of); Kim, Younghun [Kwangwoon University, Seoul (Korea, Republic of)

    2013-02-15

    Silver nanoparticles (AgNPs) are used commercially in a variety of applications, including textiles, cosmetics, spray cleaning agents, and metal products. AgNP itself, however, is classified as an environmental hazard by Environmental Protection Agency (EPA, USA) Nanotechnology White Paper, due to its toxic, persistent and bioaccumulative characteristics when exposed to the environment. We investigated the cumulative mortality and abnormalities in Japanese medaka (Oryziaslatipes) embryos after exposure to AgNPs. Free AgNPs in solution have a high activity with respect to biological interactions regarding blocking blood flow and distribution of AgNPs into the cells from head to tail of hatched O. latipes. Interestingly, the agglomeration of AgNPs (loss of nanosized characteristics) played an important role in the environmental toxicity. The present study demonstrated that when the AgNPs were exposed in the ecosystem and then formed agglomerates, nanotoxicity was reduced.

  5. Experimental study of fluidized bed agglomeration of acerola powder

    Directory of Open Access Journals (Sweden)

    G. C. Dacanal

    2008-03-01

    Full Text Available The aim of this work was to study the main effects of acerola powder on fluidized bed agglomeration. A 2(4-1 fractional factoring design was used to evaluate the main operating conditions (fluidizing air temperature, fluidizing air velocity, atomizing air flow and height of nozzle in the bed. The mechanical and physicochemical product changes were determined by analysis of particle diameter, moisture content, wetting time and bed porosity. The particle enlargement by agglomeration occurred when the relative humidity in the bed increased and, thus, the moisture of the product increased. However, the excessive increase in relative humidity resulted in a decrease in yield, caused by caking and product incrustation. The consolidation of small granules resulted in an increase in the instant properties, decreasing the wetting time and increasing the solubility in a short period of agitation.

  6. Agglomeration and Deposition Behaviour of Solid Recovered Fuel

    DEFF Research Database (Denmark)

    Pedersen, Morten Nedergaard; Jensen, Peter Arendt; Nielsen, Mads

    2015-01-01

    show that SRF ash starts melting in the range of 1150-1200 °C [6–8], which is somewhat lower than most coal ashes. However, experiments performed in fluidized bed has shown agglomeration taking place as low as 970-990 °C [9,10], and the predictability by ash fusion tests is generally poor [10]. SRF...... contains significant quantities of common plastics such as polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). Fluidized bed experiments to examine the pyrolysis of polymers have shown that bed agglomeration can result from melting plastics or sticky char residues in the case...... of PET [11,12]. The main objective of this study was to characterize the combustion of SRF and especially the deposition propensity of SRF and the main constituents of SRF. This relates both to the low temperature deposits formed during plastic pyrolysis and the high temperature deposits formed by ash...

  7. Bifurcation theory for hexagonal agglomeration in economic geography

    CERN Document Server

    Ikeda, Kiyohiro

    2014-01-01

    This book contributes to an understanding of how bifurcation theory adapts to the analysis of economic geography. It is easily accessible not only to mathematicians and economists, but also to upper-level undergraduate and graduate students who are interested in nonlinear mathematics. The self-organization of hexagonal agglomeration patterns of industrial regions was first predicted by the central place theory in economic geography based on investigations of southern Germany. The emergence of hexagonal agglomeration in economic geography models was envisaged by Krugman. In this book, after a brief introduction of central place theory and new economic geography, the missing link between them is discovered by elucidating the mechanism of the evolution of bifurcating hexagonal patterns. Pattern formation by such bifurcation is a well-studied topic in nonlinear mathematics, and group-theoretic bifurcation analysis is a well-developed theoretical tool. A finite hexagonal lattice is used to express uniformly distri...

  8. Parallel Element Agglomeration Algebraic Multigrid and Upscaling Library

    Energy Technology Data Exchange (ETDEWEB)

    2015-02-19

    ParFELAG is a parallel distributed memory C++ library for numerical upscaling of finite element discretizations. It provides optimal complesity algorithms ro build multilevel hierarchies and solvers that can be used for solving a wide class of partial differential equations (elliptic, hyperbolic, saddle point problems) on general unstructured mesh (under the assumption that the topology of the agglomerated entities is correct). Additionally, a novel multilevel solver for saddle point problems with divergence constraint is implemented.

  9. The role of agglomeration in the conductivity of carbon nanotube composites near percolation

    Science.gov (United States)

    Tarlton, Taylor; Sullivan, Ethan; Brown, Joshua; Derosa, Pedro A.

    2017-02-01

    A detailed study of agglomeration in composite materials containing carbon nanotubes (CNT) is presented. Three dimensional samples with different degrees of agglomeration were created in three different ways, leading to a wider range of geometries available to study. Virtual charges are injected into the computer-generated samples and move through these samples according to a Monte Carlo hopping algorithm. Results show that there is an optimal level of agglomeration that is actually beneficial for charge transport at low volume concentrations, lowering the percolation threshold. It is found that near percolation, a more uniform CNT distribution (less agglomeration) leads to more conductive paths, but with a lower mobility. The optimum level of agglomeration comes from a trade off between these two properties. Beyond this optimum agglomeration state, it is observed that conductivity tends to decrease as dispersion increases at all concentrations studied here. At high concentration (percolated samples), where CNT clumps merge, conductivity seems to be less sensitive to agglomeration.

  10. Analysis on the Spatial-Temporal Dynamics of Financial Agglomeration with Markov Chain Approach in China

    Directory of Open Access Journals (Sweden)

    Weimin Chen

    2014-01-01

    Full Text Available The standard approach to studying financial industrial agglomeration is to construct measures of the degree of agglomeration within financial industry. But such measures often fail to exploit the convergence or divergence of financial agglomeration. In this paper, we apply Markov chain approach to diagnose the convergence of financial agglomeration in China based on the location quotient coefficients across the provincial regions over 1993–2011. The estimation of Markov transition probability matrix offers more detailed insights into the mechanics of financial agglomeration evolution process in China during the research period. The results show that the spatial evolution of financial agglomeration changes faster in the period of 2003–2011 than that in the period of 1993–2002. Furthermore, there exists a very uneven financial development patterns, but there is regional convergence for financial agglomeration in China.

  11. Le logement social urbain et la dynamique spatiale. Stratégie des acteurs décideurs à Oran (1990-2000)

    OpenAIRE

    Said, Aïmène

    2013-01-01

    Le constat établi depuis plus d’une décennie, sur la ville d’Oran, fait état d’un mouvement de développement urbain assez intense. Cette dynamique urbaine bien que périphérique se caractérise par une production massive de logements. Avec ses diverses configurations immobilières, le logement social tient une place centrale dans cette production, pour devenir et de loin, le premier consommateur foncier. Notre article tente de suivre l’apport des filières de logement social dans le tracé urbain....

  12. Reversible or not? Distinguishing agglomeration and aggregation at the nanoscale.

    Science.gov (United States)

    Sokolov, Stanislav V; Tschulik, Kristina; Batchelor-McAuley, Christopher; Jurkschat, Kerstin; Compton, Richard G

    2015-10-06

    Nanoparticles are prone to clustering either via aggregation (irreversible) or agglomeration (reversible) processes. It is exceedingly difficult to distinguish the two via conventional techniques such as dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), or electron microscopy imaging (scanning electron microscopy (SEM), transmission electron microscopy (TEM)) as such techniques only generally confirm the presence of large particle clusters. Herein we develop a joint approach to tackle the issue of distinguishing between nanoparticle aggregation vs agglomeration by characterizing a colloidal system of Ag NPs using DLS, NTA, SEM imaging and the electrochemical nanoimpacts technique. In contrast to the conventional techniques which all reveal the presence of large clusters of particles, electrochemical nanoimpacts provide information regarding individual nanoparticles in the solution phase and reveal the presence of small nanoparticles (<30 nm) even in high ionic strength (above 0.5 M KCl) and allow a more complete analysis. The detection of small nanoparticles in high ionic strength media evidence the clustering to be a reversible process. As a result it is concluded that agglomeration rather than irreversible aggregation takes place. This observation is of general importance for all colloids as it provides a feasible analysis technique for a wide range of systems with an ability to distinguish subtly different processes.

  13. Nifedipine Nanoparticle Agglomeration as a Dry Powder Aerosol Formulation Strategy

    Science.gov (United States)

    Plumley, Carl; Gorman, Eric M.; Munson, Eric J.; Berkland, Cory

    2009-01-01

    Efficient administration of drugs represents a leading challenge in pulmonary medicine. Dry powder aerosols are of great interest compared to traditional aerosolized liquid formulations in that they may offer improved stability, ease of administration, and simple device design. Particles 1–5 µm in size typically facilitate lung deposition. Nanoparticles may be exhaled as a result of their small size; however, they are desired to enhance the dissolution rate of poorly soluble drugs. Nanoparticles of the hypertension drug nifedipine were co-precipitated with stearic acid to form a colloid exhibiting negative surface charge. Nifedipine nanoparticle colloids were destabilized by using sodium chloride to disrupt the electrostatic repulsion between particles as a means to achieve the agglomerated nanoparticles of a controlled size. The aerodynamic performance of agglomerated nanoparticles was determined by cascade impaction. The powders were found to be well suited for pulmonary delivery. In addition, nanoparticle agglomerates revealed enhanced dissolution of the drug species suggesting the value of this formulation approach for poorly water soluble pulmonary medicines. Ultimately, nifedipine powders are envisioned as an approach to treat pulmonary hypertension. PMID:19015016

  14. Combustion of metal agglomerates in a solid rocket core flow

    Science.gov (United States)

    Maggi, Filippo; Dossi, Stefano; DeLuca, Luigi T.

    2013-12-01

    The need for access to space may require the use of solid propellants. High thrust and density are appealing features for different applications, spanning from boosting phase to other service applications (separation, de-orbiting, orbit insertion). Aluminum is widely used as a fuel in composite solid rocket motors because metal oxidation increases enthalpy release in combustion chamber and grants higher specific impulse. Combustion process of metal particles is complex and involves aggregation, agglomeration and evolution of reacting particulate inside the core flow of the rocket. It is always stated that residence time should be enough in order to grant complete metal oxidation but agglomerate initial size, rocket grain geometry, burning rate, and other factors have to be reconsidered. New space missions may not require large rocket systems and metal combustion efficiency becomes potentially a key issue to understand whether solid propulsion embodies a viable solution or liquid/hybrid systems are better. A simple model for metal combustion is set up in this paper. Metal particles are represented as single drops trailed by the core flow and reacted according to Beckstead's model. The fluid dynamics is inviscid, incompressible, 1D. The paper presents parametric computations on ideal single-size particles as well as on experimental agglomerate populations as a function of operating rocket conditions and geometries.

  15. Contact mechanics of highly porous oxide nanoparticle agglomerates

    Science.gov (United States)

    Fabre, Andrea; Salameh, Samir; Ciacchi, Lucio Colombi; Kreutzer, Michiel T.; van Ommen, J. Ruud

    2016-07-01

    Efficient nanopowder processing requires knowledge of the powder's mechanical properties. Due to the large surface area to volume ratio, nanoparticles experience relatively strong attractive interactions, leading to the formation of micron-size porous structures called agglomerates. Significant effort has been directed towards the development of models and experimental procedures to estimate the elasticity of porous objects such as nanoparticle agglomerates; however, none of the existing models has been validated for solid fractions below 0.1. Here, we measure the elasticity of titania (TiO_2, 22 nm), alumina (Al_2O_3, 8 nm), and silica (SiO_2, 16 nm) nanopowder agglomerates by Atomic Force Microscopy, using a 3.75 μm glass colloid for the stress-strain experiments. Three sample preparations with varying degree of powder manipulation are assessed. The measured Young's moduli are in the same order of magnitude as those predicted by the model of Kendall et al., thus validating it for the estimation of the Young's modulus of structures with porosity above 90 %.

  16. La gouvernance urbaine et l'échec d'une ville homogène : les faits ...

    African Journals Online (AJOL)

    Ces modes mal intégrés dans l'architecture institutionnelle ne bénéficient pas du consensus non seulement au niveau des acteurs du secteur mais encore entre les acteurs urbains. Evoquer ... The result tends to be a dual urban landscape, in which different actors pursue their own interests and develop their own networks.

  17. L'agriculture urbaine pourrait accroître la sécurité alimentaire dans ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    L'agriculture urbaine locale offre une solution à l'insécurité alimentaire, affirment des chercheurs financés par le CRDI dans un article que le Centre international de hautes études agronomiques méditerranéennes a publié dans sa Lettre de veille de septembre 2011.

  18. Influence of excipients and processing conditions on the development of agglomerates of racecadotril by crystallo-co-agglomeration

    OpenAIRE

    Garala, Kevin; Patel, Jaydeep; Patel, Anjali; Raval, Mihir; Dharamsi, Abhay

    2012-01-01

    Purpose: The purpose of the present investigation was to improve the flow and mechanical properties of racecadotril by a crystallo-co-agglomeration (CCA) technique. Direct tableting is a requirement of pharmaceutical industries. Poor mechanical properties of crystalline drug particles require wet granulation which is uneconomical, laborious, and tedious. Materials and Methods: The objective of this work was to study the influence of various polymers/excipients and processing conditions on the...

  19. Preparation and evaluation of agglomerated crystals by crystallo-co-agglomeration: an integrated approach of principal component analysis and Box-Behnken experimental design.

    Science.gov (United States)

    Garala, Kevin C; Patel, Jaydeep M; Dhingani, Anjali P; Dharamsi, Abhay T

    2013-08-16

    Poor mechanical properties of crystalline drug particles require wet granulation technique for tablet production which is uneconomical, laborious, and tedious. The present investigation was aimed to improve flow and mechanical properties of racecadotril (RCD), a poorly water soluble antidiarrheal agent, by a crystallo-co-agglomeration (CCA) technique. The influence of various excipients and processing conditions on formation of directly compressible agglomerates of RCD was evaluated. Principal component analysis and Box-Behnken experimental design was implemented to optimize the agglomerates with good micromeritics and mechanical properties. The overall yield of the process was 88-98% with size of agglomerates between 351 and 1214 μm. Further, higher rotational speed reduced the size of agglomerates and disturbed sphericity. The optimized batch of agglomerates exhibited excellent flowability and crushing strength. The optimized batch of RCD agglomerates was characterized by fourier transform infrared spectroscopy, differential scanning calorimetry, powder X-ray diffractometry and gas chromatography which illustrated absence of drug-excipient interaction with minimal entrapment of residual solvent. Hence, it may be concluded that both excipients and processing conditions played a vital role to prepare spherical crystal agglomerates of RCD by CCA and it can be adopted as an excellent alternative to wet granulation. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Void forming index: A new parameter for detecting microstructural transformation caused by powder agglomeration.

    Science.gov (United States)

    Maruyama, Sunao; Yonemochi, Etsuo; Hasegawa, Susumu; Suzuki, Satoshi; Minami, Hidemi

    2017-10-30

    As powder agglomeration during storage causes a decrease in the performance of dry powder inhalers (DPIs), it is important to understand the properties of powder agglomeration in developing DPIs. Generally, powder agglomeration is caused by capillary force and crystalline transformation in conditions of higher humidity. It is, however, difficult to correlate crystalline transformation and powder agglomeration, especially when the crystalline transformation is limited. In this study, we focused on the application of inverse gas chromatography (iGC) to detect powder agglomeration directly. There was a slight change between the powder state and lactose agglomerates using powder X-ray diffraction, and dynamic vapor sorption. On the other hand, a change in pressure drop was found during measurement of lactose using iGC. After measurement by iGC, powdered lactose agglomerated. This finding suggests that a pressure drop is related to powder agglomeration and can be employed to detect the onset of powder agglomeration. Based on these findings, we propose a novel index-the Void Forming Index (VFI)-which is related to the pressure drop with iGC. The VFI is a useful index in the evaluation of powder agglomeration, and will be especially useful during DPI development. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Atmospheric pollution; Pollution atmospherique

    Energy Technology Data Exchange (ETDEWEB)

    Lambrozo, J.; Guillossou, G. [EDF-Gas de France, Service des Etudes Medicales, 75 - Paris (France)

    2008-10-15

    The atmosphere is the reservoir of numerous pollutants (nitrogen oxides, sulfur oxides, carbon oxides, particulates, volatile organic compounds, polycyclic aromatic hydrocarbons) from natural origin or anthropogenic origin ( industry, transport, agriculture, district heating). With epidemiologic studies the atmospheric pollution is associated with an increase of respiratory and cardiovascular diseases. At the european level, the technological progress, the legislation have allowed a reduction of pollutant emissions, however these efforts have to be continued because the sanitary impact of atmospheric pollution must not be underestimated, even if the risks appear less important that these ones in relation with tobacco, inside pollution or others factors of cardiovascular risks. Indeed, on these last factors an individual action is possible for the exposure to air pollution people have no control. (N.C.)

  2. Inventur, Inventaire des modèles du champ urbain : Éléments d'analyse des modèles inventoriés

    OpenAIRE

    Siret, Daniel

    1999-01-01

    Présentation de l'enquête de recensement des modèles existants actuellement dans le champ urbain et analyse des 64 questionnaires reçus en essayant de faire ressortir les différentes problématiques de la modélisation urbaine, les motivations des différents créateurs de modèle, l'opérationalité des modèles recensés.

  3. Stratégies pour valoriser l’environnement physique dans les zones urbaines défavorisées - : Exemples de bonnes pratiques en Europe

    NARCIS (Netherlands)

    Wassenberg, F.; Wassenberg, F.; Van Meer, A.; Van Kempen, R.

    2010-01-01

    Le changement urbain s’étend sur tous les âges. Certains quartiers ne s’adaptent pas graduellement aux circonstances qui évoluent, mais glissent dans la défavorisation. Des politiques urbaines sont nécessaires pour redynamiser ces régions. Dans toute l’Europe, les villes ont des zones défavorisées

  4. Field observations of artificial sand and oil agglomerates

    Science.gov (United States)

    Dalyander, Patricia (Soupy); Long, Joseph W.; Plant, Nathaniel G.; McLaughlin, Molly R.; Mickey, Rangley C.

    2015-01-01

    Oil that comes into the surf zone following spills, such as occurred during the 2010 Deepwater Horizon (DWH) blowout, can mix with local sediment to form heavier-than-water sand and oil agglomerates (SOAs), at times in the form of mats a few centimeters thick and tens of meters long. Smaller agglomerates that form in situ or pieces that break off of larger mats, sometimes referred to as surface residual balls (SRBs), range in size from sand-sized grains to patty-shaped pieces several centimeters (cm) in diameter. These mobile SOAs can cause beach oiling for extended periods following the spill, on the scale of years as in the case of DWH. Limited research, including a prior effort by the U.S. Geological Survey (USGS) investigating SOA mobility, alongshore transport, and seafloor interaction using numerical model output, focused on the physical dynamics of SOAs. To address this data gap, we constructed artificial sand and oil agglomerates (aSOAs) with sand and paraffin wax to mimic the size and density of genuine SOAs. These aSOAs were deployed in the nearshore off the coast of St. Petersburg, Florida, during a field experiment to investigate their movement and seafloor interaction. This report presents the methodology for constructing aSOAs and describes the field experiment. Data acquired during the field campaign, including videos and images of aSOA movement in the nearshore (1.5-meter and 0.5-meter water depth) and in the swash zone, are also presented in this report.

  5. Sample to sample fluctuations in fragmentation and agglomeration processes

    CERN Document Server

    Olla, P

    1995-01-01

    The fluctuations in the particle size distribution for processes of fragmentation and aggregation are studied for stationary state regimes. The system is described in terms of a stochastic process over an adequate tree structure. The RMS fluctuations appear to scale with the square root of the mean distribution, as in the case of sums of statistically independent events. Implications for the applicability of a mean field description to fragmentation and agglomeration processes, and possible relation with intermittency phenomena in three dimensional turbulence are discussed.

  6. A phenomenological model for improving understanding of the ammonium nitrate agglomeration process

    Directory of Open Access Journals (Sweden)

    Videla Leiva Alvaro

    2016-01-01

    Full Text Available Ammonium nitrate is intensively used as explosive in the mining industry as the main component of ANFO. The ammonium nitrate is known to be a strong hygroscopic crystal matter which generates problems due to the creation of water bridges between crystals leading later to nucleation and crystallization forming an agglomerated solid cake. The agglomeration process damages the ammonium nitrate performance and is undesirable. Usually either organic or inorganic coatings are used to control agglomeration. In the present work a characterization method of humidity adsorption of the ammonium nitrate crystal was performed under laboratory conditions. Several samples were exposed into a defined humidity in a controlled chamber during 5 hours after which the samples were tested to measure agglomeration as the resistance force to compression. A clear relation was found between coating protection level, humidity and agglomeration. Agglomeration can be then predicted by a phenomenological model based of combination of the mono-layer BET adsorption and CNT nucleation models.

  7. Modeling of agglomerates formation and evolution at combustion of aluminized propellants in intra-chamber environments

    OpenAIRE

    Babuk Valery A.; Nizyaev Alexander A.

    2017-01-01

    In the present paper, the solution of the problem of agglomerates parameters calculation in combustion chamber environments is described. For this, a method of two-dimensional axisymmetric multiphase quasistationary flow calculation has been developed. The method uses previously developed models of agglomerates formation and their evolution within multiphase flow with considering of interactions between agglomerates and gaseous combustion products. Parametric study of the developed models wit...

  8. Modeling of agglomerates formation and evolution at combustion of aluminized propellants in intra-chamber environments

    Directory of Open Access Journals (Sweden)

    Babuk Valery A.

    2017-01-01

    Full Text Available In the present paper, the solution of the problem of agglomerates parameters calculation in combustion chamber environments is described. For this, a method of two-dimensional axisymmetric multiphase quasistationary flow calculation has been developed. The method uses previously developed models of agglomerates formation and their evolution within multiphase flow with considering of interactions between agglomerates and gaseous combustion products. Parametric study of the developed models with respect to intra-chamber environments has been performed.

  9. Generalized flooded agglomerate model for the cathode catalyst layer of a polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Kamarajugadda, Sai; Mazumder, Sandip

    2012-06-01

    The flooded agglomerate model has found prolific usage in modeling the oxygen reduction reaction within the cathode catalyst layer of a polymer electrolyte membrane fuel cell (PEMFC). The assumption made in this model is that the ionomer-coated carbon-platinum agglomerate is spherical in shape and that the spheres are non-overlapping. This assumption is convenient because the governing equations lend themselves to closed-form analytical solution when a spherical shape is assumed. In reality, micrographs of the catalyst layer show that the agglomerates are best represented by sets of overlapping spheres of unequal radii. In this article, the flooded agglomerate is generalized by considering overlapping spheres of unequal radii. As a first cut, only two overlapping spheres are considered. The governing reaction-diffusion equations are solved numerically using the unstructured finite-volume method. The volumetric current density is extracted for various parametric variations, and tabulated. This sub-grid-scale generalized flooded agglomerate model is first validated and finally coupled to a computational fluid dynamics (CFD) code for predicting the performance of the PEMFC. Results show that when the agglomerates are small (<200 nm equivalent radius), the effect of agglomerate shape on the overall PEMFC performance is insignificant. For large agglomerates, on the other hand, the effect of agglomerate shape was found to be critical, especially for high current densities for which the mass transport resistance within the agglomerate is strongly dependent on the shape of the agglomerate, and was found to correlate well with the surface-to-volume ratio of the agglomerate.

  10. Drivers of Agglomeration Effects in Retailing – the Shopping Mall Tenant’s Perspective

    OpenAIRE

    Teller, C; Schnedlitz, P.

    2011-01-01

    Retail and service enterprises seek benefits and synergies from locating their stores within retail agglomerations, such as shopping streets and malls. The aim of this paper is to identify the main drivers of such synergetic or ‘agglomeration effects’ for tenants. A literature review reveals four sets of drivers that are related to the location, the tenant mix, the marketing, and the management of an agglomeration. Based on a survey of 217 managers representing stores that are located in five...

  11. Le droit, réponse aux incertitudes des problématiques urbaines ?

    Directory of Open Access Journals (Sweden)

    Alexandre Coque

    2007-05-01

    Full Text Available Face aux incertitudes, liées aux évolutions des problématiques urbaines, les différents acteurs sont amenés à replacer la norme juridique au centre de leurs interventions afin de rétablir une situation de stabilité et de confiance. Le droit au sens large du terme — loi, contrat, syndic de copropriété, règlement du lotissement… — apporterait donc les moyens de l’adaptation à l’incertitude vécue. Cet ouvrage, rédigé par sept auteurs, sociologues et urbanistes, regroupe ...

  12. Agir contre la relégation urbaine et pour le droit à la ville

    Directory of Open Access Journals (Sweden)

    Alexis Sierra

    2010-05-01

    Full Text Available Serge Allou, ancien directeur du Groupe de Recherche et Echanges Technologiques (GRET (2000 - 2006, expert, professeur associé à l’Institut Français d’Urbanisme responsable du cursus « Expertise internationale - Villes en développement », a représenté le GRET au Ve Forum Urbain Mondial à Rio.Le GRET www.gret.org est une ONG créée en 1976. Elle a pour but de mettre en œuvre des projets de développement  financés par des bailleurs de fonds publics et privés, de réaliser des expertises et des ...

  13. Oblet Thierry, Gouverner la ville. Les voies urbaines de la démocratie moderne

    Directory of Open Access Journals (Sweden)

    Bernard Jouve

    2007-05-01

    Full Text Available La France est actuellement en pleine phase d’introspection à la suite des émeutes urbaines qui ont secoué certaines banlieues au cours du mois de novembre 2005, qui se sont traduites par l’incendie de quelque 10 000 véhicules particuliers et un coût total de 200 millions d’euros de dégâts. Autant dire que le livre de Thierry Oblet, publié en avril 2005, rencontre une actualité « brûlante » qui interpelle le « modèle social français » et qui s’enracine dans un racisme de la vie ordinaire, dans...

  14. De fragments en totalité : le paysage, un analyseur des mondes urbains. Introduction

    Directory of Open Access Journals (Sweden)

    Laurent Matthey

    2009-10-01

    Full Text Available De la campagne à la ville En 1802, K.G. Schelle se proposait, dans un court traité, d’examiner « la palette des impressions procurées par les promenades » pour en « augmenter et multiplier » le plaisir (1802 : 23. Par son propos, ce traité constitue un gué vers un art de se promener en milieu urbain, une manière de s’y mouvoir, une façon d’y vivre. Il constitue un des nombreux points d’entrée du paysage dans l’univers de la ville. L’auteur s’y attachait, par exemple, à fonder la nécessité de...

  15. Particle agglomeration of chitosan-magnesium aluminum silicate nanocomposites for direct compression tablets.

    Science.gov (United States)

    Khlibsuwan, Rapee; Pongjanyakul, Thaned

    2017-11-16

    Exfoliated nanocomposites of chitosan-magnesium aluminum silicate (CS-MAS) particles are characterized by good compressibility but poor flowability. Thus, the aims of this study were to investigate agglomerates of CS-MAS nanocomposites prepared using the agglomerating agents water, ethanol, or polyvinylpyrrolidone (PVP) for flowability enhancement and to evaluate the agglomerates obtained as direct compression fillers for tablets. The results showed that the addition of agglomerating agents did not affect crystallinity, but slightly influenced thermal behavior of the CS-MAS nanocomposites. The agglomerates prepared using water were larger than those prepared using 95% ethanol because high swelling of the layer of chitosonium acetate occurred, allowing formation of solid bridges and capillary force between particles, leading to higher flowability and particle strength. Incorporation of PVP resulted in larger agglomerates with good flowability and high strength due to the binder hardening mechanism. The tablets prepared from agglomerates using water showed lower hardness, shorter disintegration times and faster drug release than those using 95% ethanol. In contrast, greater hardness and more prolonged drug release were obtained from the tablets prepared from agglomerates using PVP. Additionally, the agglomerates of CS-MAS nanocomposites showed good carrying capacity and provided desirable characteristics of direct compression tablets. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. La place de la biodiversité dans les documents de planification urbaine en France

    Directory of Open Access Journals (Sweden)

    Fernanda Moscarelli

    2016-12-01

    Full Text Available La prise de conscience par les acteurs sociaux et politiques des enjeux environnementaux et de la nécessité de conservation de la biodiversité va conduire à de nouvelles politiques et à l’utilisation d’outils de planification territoriale novateurs comme le Schéma de Cohérence Territorial (SCoT. Le SCoT est l’instrument central de l’aménagement communautaire urbain français, qui associe le rôle d’assemblage de plusieurs politiques sectorielles et de coordination multi-scalaire aux objectifs de conception de villes durables. Il est donc souhaité que les SCoTs soient capables: (a d’améliorer les procédures d’aménagement par l’instauration de territoires de planification mieux adaptés aux enjeux, (b d’élargir le dialogue entre acteurs et société civile et (c d’agir pour la “soutenabilité” des villes. Nous nous interrogeons ici sur la prise en compte de la biodiversité dans les stratégies et prescriptions mises en place par les SCoTs de la Communauté d’Agglomération de Montpellier et de la Région Urbaine Grenobloise. A partir d’une analyse empirique, nous prétendons identifier les stratégies prescrites et les limites de ces documents d’urbanisme en ce qui concerne ces stratégies et leur application, la pertinence des périmètres de projet et d’action.

  17. Surveiller et classer : deux chantiers pour une recherche urbaine critique

    Directory of Open Access Journals (Sweden)

    Fabrice Bardet

    2010-07-01

    Full Text Available Après avoir navigué entre deux continents, Bernard Jouve s’était donné pour ambition de développer, au sein du monde académique français, une pensée critique sur la ville inspirée de la recherche urbaine nord-américaine et de diffuser ces réflexions au sein du monde social. Ce goût pour les analyses critiques sur le « fait urbain » a constitué, sous son impulsion, un élément fédérateur pour l’équipe de recherche lyonnaise qu’il a dirigée au cours des dernières années. A travers des exemples tirés de nos travaux sur les classements de ville et la surveillance, on montre qu’il en demeure aujourd’hui encore un important fil conducteur.Bernard Jouve lived a rich experience between two different academic worlds. That is the principle reason why he aimed to develop a critical thought on urban changes and cities in the midst of French academic world. Further, he wanted to spread these analysis inspired by North-American urban research among actors playing a role in urban policies. For the research team that he managed in Lyon for these last years, this interest became, and remains, a unifier element.

  18. Combination Chemotherapeutic Dry Powder Aerosols via Controlled Nanoparticle Agglomeration

    Science.gov (United States)

    El-Gendy, Nashwa; Berkland, Cory

    2014-01-01

    Purpose To develop an aerosol system for efficient local lung delivery of chemotherapeutics where nanotechnology holds tremendous potential for developing more valuable cancer therapies. Concurrently, aerosolized chemotherapy is generating interest as a means to treat certain types of lung cancer more effectively with less systemic exposure to the compound. Methods Nanoparticles of the potent anticancer drug, paclitaxel, were controllably assembled to form low density microparticles directly after preparation of the nanoparticle suspension. The amino acid, L-leucine, was used as a colloid destabilizer to drive the assembly of paclitaxel nanoparticles. A combination chemotherapy aerosol was formed by assembling the paclitaxel nanoparticles in the presence of cisplatin in solution. Results Freeze-dried powders of the combination chemotherapy possessed desirable aerodynamic properties for inhalation. In addition, the dissolution rates of dried nanoparticle agglomerate formulations (~60% to 66% after 8 h) were significantly faster than that of micronized paclitaxel powder as received (~18% after 8 h). Interestingly, the presence of the water soluble cisplatin accelerated the dissolution of paclitaxel. Conclusions Nanoparticle agglomerates of paclitaxel alone or in combination with cisplatin may serve as effective chemotherapeutic dry powder aerosols to enable regional treatment of certain lung cancers. PMID:19415471

  19. Agglomeration of Luminescent Porous Silicon Nanoparticles in Colloidal Solutions.

    Science.gov (United States)

    Herynková, Kateřina; Šlechta, Miroslav; Šimáková, Petra; Fučíková, Anna; Cibulka, Ondřej

    2016-12-01

    We have prepared colloidal solutions of clusters composed from porous silicon nanoparticles in methanol, water and phosphate-buffered saline (PBS). Even if the size of the nanoclusters is between 60 and 500 nm, due to their highly porous "cauliflower"-like structure, the porous silicon nanoparticles are composed of interconnected nanocrystals having around 2.5 nm in size and showing strong visible luminescence in the orange-red spectral region (centred at 600-700 nm). Hydrophilic behaviour and good solubility of the nanoclusters in water and water-based solutions were obtained by adding hydrogen peroxide into the etching solution during preparation and 16 min long after-bath in hydrogen peroxide. By simple filtration of the solutions with syringe filters, we have extracted smaller nanoclusters with sizes of approx. 60-70 nm; however, these nanoclusters in water and PBS solution (pH neutral) are prone to agglomeration, as was confirmed by zeta potential measurements. When the samples were left at ambient conditions for several weeks, the typical nanocluster size increased to approx. 330-400 nm and then remained stable. However, both freshly filtered and aged samples (with agglomerated porous silicon nanoparticles) of porous silicon in water and PBS solutions can be further used for biological studies or as luminescent markers in living cells.

  20. Automated Manufacture of Fertilizing Agglomerates from Burnt Wood Ash

    Energy Technology Data Exchange (ETDEWEB)

    Svantesson, Thomas

    2002-12-01

    In Sweden, extensive research is conducted to find alternative sources of energy that should partly replace the electric power production from nuclear power. With the ambition to create a sustainable system for producing energy, the use of renewable energy is expected to grow further and biofuels are expected to account for a significant part of this increase. However, when biofuels are burned or gasified, ash appears as a by-product. In order to overcome the problems related to deposition in land fills, the idea is to transform the ashes into a product - agglomerates - that easily could be recycled back to the forest grounds; as a fertilizer, or as a tool to reduce the acidification in the forest soil at the spreading area. This work considers the control of a transformation process, which transforms wood ash produced at a district heating plant into fertilizing agglomerates. A robust machine, built to comply with the industrial requirements for continuous operation, has been developed and is controlled by an industrial control system in order to enable an automated manufacture.

  1. Single domain PEMFC model based on agglomerate catalyst geometry

    Science.gov (United States)

    Siegel, N. P.; Ellis, M. W.; Nelson, D. J.; von Spakovsky, M. R.

    A steady two-dimensional computational model for a proton exchange membrane (PEM) fuel cell is presented. The model accounts for species transport, electrochemical kinetics, energy transport, current distribution, and water uptake and release in the catalyst layer. The governing differential equations are solved over a single computational domain, which consists of a gas channel, gas diffusion layer, and catalyst layer for both the anode and cathode sides of the cell as well as the solid polymer membrane. The model for the catalyst regions is based on an agglomerate geometry, which requires water species to exist in both dissolved and gaseous forms simultaneously. Data related to catalyst morphology, which was required by the model, was obtained via a microscopic analysis of a commercially available membrane electrode assembly (MEA). The coupled set of differential equations is solved with the commercial computational fluid dynamics (CFD) solver, CFDesign™, and is readily adaptable with respect to geometry and material property definitions. The results show that fuel cell performance is highly dependent on catalyst structure, specifically the relative volume fractions of gas pores and polymer membrane contained within the active region as well as the geometry of the individual agglomerates.

  2. Appréhender le territoire urbain en Méditerranée (XVIIe-XIXe siècles

    Directory of Open Access Journals (Sweden)

    Thierry Allain

    2012-02-01

    Full Text Available « Qui fait la ville ? Pour qui ? » La double interrogation lancée par Jean-Claude Perrot dans l’introduction de son ouvrage magistral paru en 1975 est toujours aussi pertinente. Elle indiquait de façon éclatante que l’espace urbain ne devait plus être considéré comme un simple décor, un cadre neutre, un poste d’observation comme un autre, censé refléter les évolutions de toute nature affectant l’Europe des Temps modernes. Sensible au renouvellement de l’espace urbain caennais au XVIIIe siècle...

  3. Collectivités et planification urbaine spontanée : une boîte à outils ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    La planification urbaine dirigée par l'État est souvent inexistante, ce qui crée des environnements non viables et fait obstacle à l'intégration des migrants. ... institutions en vue de les aider à consolider leur rôle d'acteurs du développement crédibles dans leur pays et, dans certains cas, à l'échelle régionale et internationale.

  4. La ségrégation renforcée par l'aménagement urbain | CRDI - Centre ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    29 oct. 2015 ... Mise à jour | Villes sûres et inclusives. Quelles sont les causes de la violence urbaine ? Un urbanisme axé sur la ségrégation peut susciter des tensions communautaires et de l'insécurité. Des solutions possibles ? Prendre en compte les communautés vulnérables dans les décisions d'aménagement ...

  5. Gestion intégrée de l'eau urbaine et rurale pour une adaptation ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Gestion intégrée de l'eau urbaine et rurale pour une adaptation selon le climat dans les villes indiennes (iAdapt). Ce projet de recherche permettra à deux villes indiennes de taille moyenne et à leurs bassins de passer à une approche de gestion de l'eau intégrée et résistante aux changements climatiques, ce qui assurera ...

  6. On minimal energy dipole moment distributions in regular polygonal agglomerates

    Science.gov (United States)

    Rosa, Adriano Possebon; Cunha, Francisco Ricardo; Ceniceros, Hector Daniel

    2017-01-01

    Static, regular polygonal and close-packed clusters of spherical magnetic particles and their energy-minimizing magnetic moments are investigated in a two-dimensional setting. This study focuses on a simple particle system which is solely described by the dipole-dipole interaction energy, both without and in the presence of an in-plane magnetic field. For a regular polygonal structure of n sides with n ≥ 3 , and in the absence of an external field, it is proved rigorously that the magnetic moments given by the roots of unity, i.e. tangential to the polygon, are a minimizer of the dipole-dipole interaction energy. Also, for zero external field, new multiple local minima are discovered for the regular polygonal agglomerates. The number of found local extrema is proportional to [ n / 2 ] and these critical points are characterized by the presence of a pair of magnetic moments with a large deviation from the tangential configuration and whose particles are at least three diameters apart. The changes induced by an in-plane external magnetic field on the minimal energy, tangential configurations are investigated numerically. The two critical fields, which correspond to a crossover with the linear chain minimal energy and with the break-up of the agglomerate, respectively are examined in detail. In particular, the numerical results are compared directly with the asymptotic formulas of Danilov et al. (2012) [23] and a remarkable agreement is found even for moderate to large fields. Finally, three examples of close-packed structures are investigated: a triangle, a centered hexagon, and a 19-particle close packed cluster. The numerical study reveals novel, illuminating characteristics of these compact clusters often seen in ferrofluids. The centered hexagon is energetically favorable to the regular hexagon and the minimal energy for the larger 19-particle cluster is even lower than that of the close packed hexagon. In addition, this larger close packed agglomerate has two

  7. Performance differentials of agglomeration and strategic groups: a test of incubation and new venture strategy

    NARCIS (Netherlands)

    Amezcua, A.S.; Ratinho, Tiago; Jayamohan, P.

    2013-01-01

    Our paper investigates how nascent firms ‘performance is affected by strategic group membership and industrial agglomeration. Agglomeration is defined using geographical concentration while strategic groups are measured as incubated firms that belong to the industry most highly represented within an

  8. A MODEL FOR FINE PARTICLE AGGLOMERATION IN CIRCULATING FLUIDIZED BED ABSORBERS

    Science.gov (United States)

    A model for fine particle agglomeration in circulating fluidized bed absorbers (CFBAS) has been developed. It can model the influence of different factors on agglomeration, such as the geometry of CFBAs, superficial gas velocity, initial particle size distribution, and type of ag...

  9. Agglomeration in fluidized beds at high temperatures: Mechanisms, detection and prevention

    Energy Technology Data Exchange (ETDEWEB)

    Malte Bartels; Weigang Lin; John Nijenhuis; Freek Kapteijn; J. Ruud van Ommen [Delft University of Technology - DelftChemTech, Delft (Netherlands)

    2008-10-15

    Fluidized-bed conversion of solid fuels is a well-established and widely used technology. Yet, operational problems are encountered in industrial practice. One of the most important problems is the occurrence of agglomeration at high temperature, meaning that bed particles adhere to each other to form larger entities (agglomerates). This process is often not recognized until sudden defluidization and often leads to a costly shutdown of the whole installation. In particular, the thermal conversion of certain biomass fuels, which is becoming increasingly popular, increases the risk of agglomeration. This paper critically reviews the current research status of this topic in terms of agglomeration mechanisms, detection and counteraction strategies. To understand the complex phenomenon of agglomeration in fluidized beds at high temperatures different areas are distinguished viz. hydrodynamics, chemical reaction mechanisms, particle interaction mechanisms and molecular cramming. Special emphasis is given to the detection of agglomeration. The range of detection methods is comprised of fuel ash analysis methods to predict potential agglomeration as well as analysis methods based on (on-line) process measurements, such as pressure and temperature. Finally, different methods to counteract agglomeration phenomena are presented; they comprise operational measures, utilization of additives, alternative bed materials and improved reactor design. 176 refs., 22 figs., 1 tab.

  10. Productive Places : The influence of technological change and relatedness on agglomeration externalities

    NARCIS (Netherlands)

    Neffke, F.M.H.

    2009-01-01

    This thesis addresses the topic of agglomeration externalities. Agglomeration externalities can roughly be defined as advantages and disadvantages local firms experience when locating close to other firms. An old debate exists over the question whether firms benefit more from being close to firms in

  11. Humid storage conditions increase the dissolution rate of diazepam from solid dispersions prepared by melt agglomeration

    DEFF Research Database (Denmark)

    Jørgensen, Anna Cecilia; Torstenson, Anette Seo

    2008-01-01

    The purpose of this study is to investigate the effect of cooling mode and storage conditions on the dissolution rate of a solid dispersion prepared by melt agglomeration. The aim has been to relate this effect to the solid state properties of the agglomerates. The cooling mode had an effect on t...

  12. Problems of Research, Projects and Mechanisms for Their Implementation in Chelyabinsk City Agglomeration

    Science.gov (United States)

    Bolshakov, V. V.

    2017-11-01

    The article analyzes the research and design methods of urban agglomerations in the context of the Chelyabinsk agglomeration from the point of view of correctness, objectivity and consistency of the results obtained. The completed and approved project of the Chelyabinsk agglomeration is analysed to provide architectural and planning solutions for sustainable social and economic development according to the theories that have been formed to date. The possibility of effectuation and implementation of the approved project of the Chelyabinsk agglomeration taking in account existing specific natural, historical and socio-economic factors characteristic for the territory under consideration is examined. The authors draw the conclusions the project of the Chelyabinsk agglomeration has been developed in line with the town-planning solutions that do not reflect modern approaches based on the competitive advantages of territories and do not form a space providing transition to a modernized and innovative economy. Specific town-planning decisions have a weak justification and an undeveloped methodology for pre-project analysis and methodology for designing urban agglomerations because of absence of a full study of the phenomenon of urban agglomeration and processes occurring in it today. It is necessary to continue research in the field of development of the Chelyabinsk agglomeration with the use of a logical and objective methodology to analyze the territory and design which can lead to the formation of an urban-planning information model that reflects all the system processes and allows for predicting project solutions.

  13. Agglomeration economies, accessibility and the spatial choice behavior of relocating firms

    NARCIS (Netherlands)

    Bok, M. de; Oort, F.G. van

    2011-01-01

    A growing body of empirical urban economic studies suggests that agglomeration and accessibility externalities are important sources of the uneven distribution of economic activities across cities and regions. At the same time, little is known about the importance of agglomeration economies for

  14. Study of Agglomeration Characteristics of Hydrate Particles in Oil/Gas Pipelines

    National Research Council Canada - National Science Library

    Wang, W; Li, Y; Liu, H; Zhao, P

    2015-01-01

    ... advantages. Forces acting on hydrate particles and agglomeration characteristic of hydrate particles which are crucial for the application of the new technique in engineering field should be studied thoroughly so as to offer instruction for hydrate slurry steady flow. Based on literatures, force balance model based on hydrate agglomeration force ana...

  15. Multilevel approaches and the firm-agglomeration ambiguity in economic growth studies

    NARCIS (Netherlands)

    Oort, F.G. van; Burger, M.J.; Knoben, J.; Raspe, O.

    2012-01-01

    Empirical studies in spatial economics have shown that agglomeration economies may be a source of the uneven distribution of economic activities and economic growth across cities and regions. Both localization and urbanization economies are hypothesized to foster agglomeration and growth, but

  16. Multilevel approaches and the firm-agglomeration ambiguity in economic growth studies

    NARCIS (Netherlands)

    van Oort, F.G.|info:eu-repo/dai/nl/107712741; Burger, M.J.|info:eu-repo/dai/nl/371741092; Knoben, J.; Raspe, O.

    2012-01-01

    Empirical studies in spatial economics have shown that agglomeration economies may be a source of the uneven distribution of economic activities and economic growth across cities and regions. Both localization and urbanization economies are hypothesized to foster agglomeration and growth, but recent

  17. Multilevel Approaches and the Firm-Agglomeration Ambiguity in Economic Growth Studies

    NARCIS (Netherlands)

    F.G. van Oort (Frank); M.J. Burger (Martijn); J. Knoben (Joris); O. Raspe (Otto)

    2012-01-01

    textabstractEmpirical studies in spatial economics have shown that agglomeration economies may be a source of the uneven distribution of economic activities and economic growth across cities and regions. Both localization and urbanization economies are hypothesized to foster agglomeration and

  18. Agglomeration and Deposition Behaviour of Solid Recovered Fuel

    DEFF Research Database (Denmark)

    Pedersen, Morten Nedergaard; Jensen, Peter Arendt; Hjuler, Klaus

    2016-01-01

    Waste-derived fuels, such as solid recovered fuel (SRF), are increasingly being used in, e.g., the cement industry as a means to reduce cost. The inhomogeneous nature of SRF makes it difficult to combust, and many problems may arise within, e.g., combustion control, feeding of fuel, deposit...... formation, or accumulation of impurities. The combustion of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), wood, and SRF were studied in a rotary drum furnace. The combustion was recorded on a camera (60 frames per second), so that any agglomeration or deposition of fuel or ash...... could be monitored. PE and PP pose no significant risk of forming deposits in a combustion environment (T > 800 °C) as a result of a rapid devolatilization, while PET may cause deposits as a result of a sticky char residue. The deposition tendency of the investigated SRF is low, and it may be managed...

  19. Fluidization and mixing of nanoparticle agglomerates assisted via magnetic impaction

    Science.gov (United States)

    Scicolone, James V.; Lepek, Daniel; Louie, Lin; Davé, Rajesh N.

    2013-02-01

    Mixing of nanopowders in an environmentally benign magnetically assisted fluidized bed (MAFB) system was studied. Examination of fluidization behavior of agglomerate particulate fluidization (APF; silica R974 or R972) and agglomerate bubbling fluidization (ABF; alumina or titania) nano-powders in un-assisted and MAFB systems confirmed previous results on decreased minimum fluidization velocity and increased bed expansion of APF and ABF powders due to magnetic assistance. APF and ABF powder mixtures behaved like APF powders with the bed expansions in between those of individual constituents. Unlike previous MAFB studies, fluidization as a function of time was studied to examine its influence on nano-mixing. With time, the bed expansion reduced, and reduction was faster as magnet-to-powder ratio increased from 0:1 to 5:1, although fluidization was sustained, confirmed via the pressure drop measurements. Reduction in bed expansion was attributed to change in the nature of nanoagglomerates, which showed increased density as a function of processing time, ruling out electrostatics or elutriation as major factors. Mixtures of silica (APF) and alumina (ABF), processed at various magnet-to-powder ratios, were characterized via statistical analysis from energy dispersive x-ray spectroscopy using field emission scanning electron microscope to compute homogeneity of mixing (HoM). Magnetic assistance improved the HoM as a function of time, and was strongly related to the product of number of magnets and time, similar to previous results in magnetically assisted impaction mixing (MAIM). The best achievable HoM was significantly better than unassisted fluidization and comparable to previous results for rapid expansion of high-pressure suspensions and MAIM.

  20. A Simple Effective Flaw Model on Analyzing the Nanofiller Agglomeration Effect of Nanocomposite Materials

    Directory of Open Access Journals (Sweden)

    Arun Krishnan

    2012-01-01

    Full Text Available A special mechanics/material phenomenon involving nanocomposites is the agglomeration of nanofillers at high volume fractions of nanofillers. Numerous experimental investigations on nanocomposites have indicated a significant decrease in mechanical properties, due to the agglomeration of nanofillers. This paper describes a simple effective flaw model to correlate the local mechanical behavior of agglomerated nanoparticles with the change in global strengths of nanocomposites. The estimated bending strength reduction from our model is shown to be similar to experimental results reported by previous researchers. These results can be used as a guide for future nanocomposite design and development. Future nanomaterial manufacturing should be focused on eliminating the largest agglomerates, rather than limiting the nanofiller volume fraction. Meanwhile, by reducing the nanofiller agglomerate size, we expect that a high critical nanofiller volume fraction could be obtained to delay the mechanical property reduction.

  1. Laboratory Observations of Artificial Sand and Oil Agglomerates Video and Velocity Data: False-Floor Experiment Interpretive Video

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Weathered oil in the surf-zone after an oil spill may mix with suspended sediments to form sand and oil agglomerates (SOA). Sand and oil agglomerates may form in...

  2. Laboratory Observations of Artificial Sand and Oil Agglomerates Video and Velocity Data: Sea Floor Interaction Experiment Interpretive Video

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Weathered oil in the surf-zone after an oil spill may mix with suspended sediments to form sand and oil agglomerates (SOA). Sand and oil agglomerates may form in...

  3. Laboratory Observations of Artificial Sand and Oil Agglomerates Video and Velocity Data: Sea Floor Interaction Experiment Flow Velocity

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Weathered oil in the surf-zone after an oil spill may mix with suspended sediments to form sand and oil agglomerates (SOA). Sand and oil agglomerates may form in...

  4. Laboratory Observations of Artificial Sand and Oil Agglomerates: Video and Velocity Data: Sea Floor Interaction Experiment Video (GoPro)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Weathered oil in the surf-zone after an oil spill may mix with suspended sediments to form sand and oil agglomerates (SOA). Sand and oil agglomerates may form in...

  5. Globalisation et changement d’échelle dans le gouvernement urbain

    Directory of Open Access Journals (Sweden)

    H.V. Savitch

    2007-10-01

    Full Text Available Cet article analyse les relations entre la mondialisation et le changement d’échelle urbaine. Il considère que les dynamiques à l’œuvre dans le processus de mondialisation (politiques néo-libérales, compétition territoriale, suburbanisation conduisent à de nouvelles contraintes pesant sur les villes. Une des réponses les plus pertinentes que les villes peuvent générer repose sur le changement d’échelle de leurs institutions en bâtissant de nouvelles structures ou en les restructurant pour renforcer leur capacité d’action. Ce processus conduit à reconfigurer les modes de gouvernance et donc le pouvoir urbain sur de nouvelles bases géographiques. Ce type de manipulation territoriale est un instrument qui agit sur l’allocation des ressources entre acteurs, en inclus certains, en exclue d’autres, établit de nouvelles priorités sur l’agenda politique. Cinq types de dynamiques institutionnelles sont présentées et analysées à partir de cas concrets: 1 les villes fusionnées 2 le gouvernement à plusieurs niveaux 3 la coopération partagée 4 les communautés urbaines et 5 les villes non contiguës. Une première évaluation est menée en tentant de mettre jour l’efficacité, le contrôle démocratique et la capacité à générer du développement économique respectifs de ces cinq modèles qui présentent tous des avantages et des inconvénients. Le recours à l’un ou l’autre de ces modèles s’explique essentiellement par les valeurs auxquels il renvoie et par des contingences politiques et économiques. Ils ne garantissent pas non plus un type particulier d’effet même si un changement d’échelle bien maîtrisé peut renforcer la position d’une ville face à la mondialisation.This article explores the relationship between globalization and urban rescaling. It suggests that forces emanating from globalization (neo liberal politics, increased competition, economic restructuring and suburbanization have

  6. La nécropole de la basilique urbaine à Sirmium

    Directory of Open Access Journals (Sweden)

    Popović Ivana

    2012-01-01

    Full Text Available L’analyse des nécropoles située à l’intérieur et autour de la basilique urbaine, sur les sites 59, 46 et 47 de Sirmium, où 28 enterrements ont été enregistrés jusqu’à aujourd’hui, a démontré qu’il s’agissait de tombes de construction identique contenant un mobilier funéraires modeste mais homogène (peignes en os tripartites à deux rangées de dents, « petites » fibules ansées en arbalète en fer, « grandes » boucles ovales en fer, couteaux en fer et fragments de récipients en fin verre de couleur verte. En l’occurrence, dans la basilique même ont été découverts deux sarcophages miniatures et 13 tombes en briques. Ces petits sarcophages, ainsi que certaines tombes miniatures, contenaient des ossements d’individus adultes, ce qui incite à conclure que les dépouilles de défunts enterrés dans les nécropoles de Sirmium, situées hors de l’enceinte de la ville, ont été transportées à quelque moment dans la nécropole nouvellement formée intra muros. La création de cette nécropole est liée à l’érection de la basilique à l’intérieur de l’enceinte de la ville en 426. La nécropole était en fonction jusqu’à la destruction hunnique de la ville en 441. [Projekat Ministarstva nauke Republike Srbije, br. 177007: La romanisation, l’urbanisation et la transformation des centres urbains du charactère civil, militaire et résidentiel dansles provinces romaines sur la territoire de Serbie

  7. A new method to quantify fluidized bed agglomeration in the combustion of biomass fuels

    Energy Technology Data Exchange (ETDEWEB)

    Oehman, M. [Umeaa Univ. (Sweden). Dept. of Chemistry

    1997-12-31

    The present licentiate thesis is a summary and discussion of four papers, dealing with the development, evaluation and use of a new method to quantify bed agglomeration tendencies for biomass fuels. An increased utilization of biomass related fuels has many environmental benefits, but also requires careful studies of potential new problems associated with these fuels such as bed agglomeration/defluidization during combustion and gasification in fluidized beds. From a thorough literature survey, no suitable methods to determine bed agglomeration tendencies of different fuels, fuel combinations or fuels with additives appeared to be available. It therefore seemed of considerable interest to develop a new method for the quantification of fluidized bed agglomeration tendencies for different fuels. A bench scale fluidized bed reactor (5 kW), specially designed to obtain a homogeneous isothermal bed temperature, is used. The method is based on controlled increase of the bed temperature by applying external heat to the primary air and to the bed section walls. The initial agglomeration temperature is determined by on- or off-line principal component analysis of the variations in measured bed temperatures and differential pressures. Samples of ash and bed material for evaluation of agglomeration mechanisms may also be collected throughout the operation. To determine potential effects of all the process related variables on the determined fuel specific bed agglomeration temperature, an extensive sensitivity analysis was performed according to a statistical experimental design. The results showed that the process variables had only relatively small effects on the agglomeration temperature, which could be determined to 899 deg C with a reproducibility of {+-} 5 deg C (STD). The inaccuracy was determined to be {+-} 30 deg C (STD). The method was also used to study the mechanism of both bed agglomeration using two biomass fuels and prevention of bed agglomeration by co

  8. Powder strength distributions for understanding de-agglomeration of lactose powders.

    Science.gov (United States)

    Das, Shyamal C; Behara, Srinivas Ravindra Babu; Bulitta, Jurgen B; Morton, David A V; Larson, Ian; Stewart, Peter J

    2012-10-01

    The purpose was to calculate distributions of powder strength of a cohesive bed to explain the de-agglomeration of lactose. De-agglomeration profiles of Lactohale 300(®) (L300) and micronized lactose (ML) were constructed by particle sizing aerosolised plumes dispersed at air flow rates of 30-180 l/min. The work of cohesion distribution was determined by inverse gas chromatography. The primary particle size and tapped density distributions were determined. Powder strength distributions were calculated by Monte Carlo simulations from distributions of particle size, work of cohesion and tapped density measurements. The powder strength distribution of L300 was broader than that of ML. Up to 85th percentile, powder strength of L300 was lower than ML which was consistent with the better de-agglomeration of L300 at low flow rates. However, ~15% of L300 particles had higher powder strength than ML which likely to cause lower de-agglomeration for L300 at high air flow rates. Cohesive lactose powders formed matrices of non-homogenous powder strength. De-agglomeration of cohesive powders has been shown to be related to powder strength. This study provided new insights into powder de-agglomeration by a new approach for calculating powder strength distributions to better understand complex de-agglomeration behaviour.

  9. Agglomeration of celecoxib by quasi-emulsion solvent diffusion method without stabilizer: effect of good solvent.

    Science.gov (United States)

    Maghsoodi, Maryam; Nokhodchi, Ali

    2017-01-12

    The aim of the present research is to investigate the feasibility of agglomeration of crystals by the quasi-emulsion solvent diffusion method without using a stabilizer. Two solvent systems comprising a solvent and an antisolvent (water) were used to prepare celecoxib agglomerates. To this end, seven solvents including propanol, methyl acetate, methyl ethyl ketone, butanol, ethyl acetate, isopropyl acetate, and pentanol were examined. The agglomerates were evaluated by micromeritic properties (e.g., size, density, flowability), yield, drug physical state, friability, and dissolution behavior. In the present study the clear trend was observed experimentally in the agglomerate properties as a function of physical properties of the solvent such as miscibility with water. Solvents with high water miscibility (25% v/v) resulted in sticky and hollow particles, while solvents with low water miscibility (3%v/v) led to the formation of agglomerates with low strength. However, the agglomerates made from the solvents with intermediate water miscibility (10% v/v), may reflect a greater integrity of the agglomerates regarding yield and strength. Results of this study offer a useful starting point for a conceptual framework to guide the selection of solvent systems for the quasi-emulsion solvent diffusion method without using a stabilizer.

  10. Henri Galinié et les « terres noires » de l’archéologie urbaine.

    Directory of Open Access Journals (Sweden)

    Isabelle Brochard

    2005-04-01

    Full Text Available L’archéologue Henri Galinié, spécialiste de l’archéologie urbaine médiévale, fondateur du Centre National d’Archéologie Urbaine et directeur de recherche au C nrs , a animé cette  journée de réflexion, rappelant tout d’abord les apports de la géographie à sa spécialité, en citant notamment les travaux de Pierre George et Jacqueline Beaujeu-Garnier. Il a ensuite dressé un bref historique de l’archéologie urbaine, situant son origine aux années 1960, lorsqu’elle ...

  11. Kinetic and Thermodynamic Effects on the Agglomeration of Magnetite Nanoparticles by Magnetic Field

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Daeseong; Kim, Hackjin [Chungnam National University, Daejeon (Korea, Republic of)

    2016-06-15

    The dynamics of agglomeration of magnetite nanoparticles studied by measuring the magnetic weight shows the kinetics of stretched exponential. During the growth of the magnetic weight, the structure of agglomerate fluctuates by temperature change. This fast relaxation that can be interpreted in terms of Boltzmann distribution indicates that the thermal equilibration is established promptly with the temperature change. Agglomerate of nanoparticles resembles protein in that both of them exist in complex structures of various conformations with different formation energies, which requires the energy landscape for understanding of dynamics in detail.

  12. Magnetic agglomeration method for size control in the synthesis of magnetic nanoparticles

    Science.gov (United States)

    Huber, Dale L [Albuquerque, NM

    2011-07-05

    A method for controlling the size of chemically synthesized magnetic nanoparticles that employs magnetic interaction between particles to control particle size and does not rely on conventional kinetic control of the reaction to control particle size. The particles are caused to reversibly agglomerate and precipitate from solution; the size at which this occurs can be well controlled to provide a very narrow particle size distribution. The size of particles is controllable by the size of the surfactant employed in the process; controlling the size of the surfactant allows magnetic control of the agglomeration and precipitation processes. Agglomeration is used to effectively stop particle growth to provide a very narrow range of particle sizes.

  13. Engineering development of selective agglomeration: Task 5, Bench- scale process testing

    Energy Technology Data Exchange (ETDEWEB)

    1991-09-01

    Under the overall objectives of DOE Contract ``Engineering Development of Selective Agglomeration,`` there were a number of specific objectives in the Task 5 program. The prime objectives of Task 5 are highlighted below: (1) Maximize process performance in pyritic sulfur rejection and BTU recovery, (2) Produce a low ash product, (3) Compare the performance of the heavy agglomerant process based on diesel and the light agglomerant process using heptane, (4) Define optimum processing conditions for engineering design, (5) Provide first-level evaluation of product handleability, and (6) Explore and investigate process options/ideas which may enhance process performance and/or product handleability.

  14. Engineering development of selective agglomeration: Task 5, Bench- scale process testing

    Energy Technology Data Exchange (ETDEWEB)

    1991-09-01

    Under the overall objectives of DOE Contract Engineering Development of Selective Agglomeration,'' there were a number of specific objectives in the Task 5 program. The prime objectives of Task 5 are highlighted below: (1) Maximize process performance in pyritic sulfur rejection and BTU recovery, (2) Produce a low ash product, (3) Compare the performance of the heavy agglomerant process based on diesel and the light agglomerant process using heptane, (4) Define optimum processing conditions for engineering design, (5) Provide first-level evaluation of product handleability, and (6) Explore and investigate process options/ideas which may enhance process performance and/or product handleability.

  15. Agglomeration Multigrid for an Unstructured-Grid Flow Solver

    Science.gov (United States)

    Frink, Neal; Pandya, Mohagna J.

    2004-01-01

    An agglomeration multigrid scheme has been implemented into the sequential version of the NASA code USM3Dns, tetrahedral cell-centered finite volume Euler/Navier-Stokes flow solver. Efficiency and robustness of the multigrid-enhanced flow solver have been assessed for three configurations assuming an inviscid flow and one configuration assuming a viscous fully turbulent flow. The inviscid studies include a transonic flow over the ONERA M6 wing and a generic business jet with flow-through nacelles and a low subsonic flow over a high-lift trapezoidal wing. The viscous case includes a fully turbulent flow over the RAE 2822 rectangular wing. The multigrid solutions converged with 12%-33% of the Central Processing Unit (CPU) time required by the solutions obtained without multigrid. For all of the inviscid cases, multigrid in conjunction with an explicit time-stepping scheme performed the best with regard to the run time memory and CPU time requirements. However, for the viscous case multigrid had to be used with an implicit backward Euler time-stepping scheme that increased the run time memory requirement by 22% as compared to the run made without multigrid.

  16. Nanoparticle embedded chitosan film for agglomeration free TEM images.

    Science.gov (United States)

    Dogan, Üzeyir; Çiftçi, Hakan; Cetin, Demet; Suludere, Zekiye; Tamer, Ugur

    2017-02-01

    Transmission electron microscopy (TEM) is a very useful and commonly used microscopy technique, used especially for the characterization of nanoparticles. However, the identification of the magnetic nanoparticle could be thought problematic in TEM analysis, due to the fact that the magnetic nanoparticles are usually form aggregates on the TEM grid to form bigger particles generating higher stability. This prevents to see exact shape and size of each nanoparticle. In order to overcome this problem, a simple process for the formation of well-dispersed nanoparticles was conducted, by covering chitosan film on the unmodified copper grid, it was said to result in aggregation-free TEM images. It is also important to fix the magnetic nanoparticles on the TEM grids, due to possible contamination of TEM filament which is operated under high vacuum conditions. The chitosan film matrix also helps to protect the TEM filament from contact with magnetic nanoparticles during the imaging process. The proposed procedure offers a quick method to fix the nanoparticles in a conventional copper TEM grid and chitosan matrix prevents agglomeration of nanoparticles, and thus getting TEM images showing well-dispersed individual nanoparticles. © 2016 Wiley Periodicals, Inc.

  17. Nearshore dynamics of artificial sand and oil agglomerates.

    Science.gov (United States)

    Dalyander, P Soupy; Plant, Nathaniel G; Long, Joseph W; McLaughlin, Molly

    2015-07-15

    Weathered oil can mix with sediment to form heavier-than-water sand and oil agglomerates (SOAs) that can cause beach re-oiling for years after a spill. Few studies have focused on the physical dynamics of SOAs. In this study, artificial SOAs (aSOAs) were created and deployed in the nearshore, and shear stress-based mobility formulations were assessed to predict SOA response. Prediction sensitivity to uncertainty in hydrodynamic conditions and shear stress parameterizations were explored. Critical stress estimates accounting for large particle exposure in a mixed bed gave the best predictions of mobility under shoaling and breaking waves. In the surf zone, the 10-cm aSOA was immobile and began to bury in the seafloor while smaller size classes dispersed alongshore. aSOAs up to 5 cm in diameter were frequently mobilized in the swash zone. The uncertainty in predicting aSOA dynamics reflects a broader uncertainty in applying mobility and transport formulations to cm-sized particles. Published by Elsevier Ltd.

  18. Monitoring of odor nuisance in the tri-city agglomeration

    Science.gov (United States)

    Gebicki, Jacek; Dymerski, Tomasz; Namieśnik, Jacek

    2016-11-01

    The paper describes a principle of operation of odor nuisance monitoring network, which is being designed in the tri-city agglomeration. Moreover, it presents the preliminary results of an investigation on ambient air quality with respect to odour nuisance in a vicinity of the municipal landfill. The investigation was performed during spring-winter season using a prototype of electronic nose and the Nasal Ranger field olfactometers. The prototype was equipped with a set of six semiconductor sensors by FIGARO Co. and one PID-type sensor. The field olfactometers were used to determine mean concentration of odorants, which amounted from 2.2 to 30.2 ou/m3 depending on the place of measurement. In case of the investigation with the electronic nose prototype a classification of the ambient air samples with respect to the place of sampling was performed utilizing kNN algorithm supported with a cross-validation method. Correct classification of the ambient air samples was at the level of 66.7%. Performed investigation revealed that discrimination of the ambient air samples differing in concentration of odorants and place of origin was possible.

  19. Modélisation de la dispersion de polluants à l'échelle intra-urbaine, mise en place d'indicateurs morphologiques

    OpenAIRE

    Maignant, Gilles

    2006-01-01

    16 pages; Les villes regroupent de plus en plus d'habitants produisant des flux de trafic intra - urbains sans cesse plus importants, flux qui risquent de nuire à la durabilité de ces villes. Afin d'estimer l'impact de la circulation automobile en matière de pollution de l'air, des modèles de simulation ont été construits. Ces modèles tridimensionnels (développés sous interface MISKAM) intègrent la morphologie urbaine en trois dimensions, les phénomènes complexes de climatologie, notamment de...

  20. Des coûts de transaction et de développement incompressibles ? L’exemple du remembrement urbain en Wallonie

    OpenAIRE

    Lejeune, Zoé; Marique, Anne-Françoise; Teller, Jacques; Michel, Quentin; Halleux, Jean-Marie

    2010-01-01

    La Région wallonne (Belgique) souhaite simplifier et raccourcir les procédures administratives liées au renouvellement urbain à travers la mise en place d’une procédure d’exception pour les projets d’envergure : le remembrement urbain. La prise en compte des modes d’appropriation de ce nouveau dispositif par les acteurs de l’aménagement et de la promotion immobilière en donnent un autre éclairage. Peer reviewed

  1. Evaluation of the effect of some additives on the efficiency of binder liquid in wet agglomeration of crystals.

    Science.gov (United States)

    Maghsoodi, Maryam; Nabizadeh, Hassan; Nokhodchi, Ali

    2017-09-01

    Wet agglomeration is a process wherein dispersed particles are held together in an aggregated form by the presence of a small quantity of solvent which acts as binder liquid. In this work, the efficiency of binder liquid was tested in the presence of various additives. Solid state of carbamazepine (CBZ) agglomerates was characterized by DSC and FT-IR. The obtained agglomerates were also investigated in terms of yield, size distribution, friability, and drug release. CBZ agglomerates formed only in the presence of talc, span, and croscarmellose sodium (CCS), whereas ethyl cellulose and eudragit RS100 failed to make CBZ agglomerates. The presence of talc decreased the agglomerate size and produced CBZ agglomerates with a poor strength. However, span and CCS led to larger agglomerates with superior strength. In contrast to CCS samples, span and talc altered the dissolution rate of CBZ. FT-IR results showed that there is an interaction between CCS and drug. This study suggests that care must be taken when additives are used to manufacture agglomerates as the type of additives even in low concentrations can have a big impact on the efficiency of the binder liquid in forming agglomerates thereby affecting the quality of agglomerates.

  2. À la recherche des chronotopes du roman urbain. Une cartographie des Mystères de Bruxelles (1845-1846

    Directory of Open Access Journals (Sweden)

    Paul Aron

    2017-07-01

    Full Text Available Une des premières ambitions du roman urbain qui s’impose au milieu du 19e siècle est de donner à lire la ville dans sa structure et sa composition sociale. Ce genre romanesque a été étudié sur le plan thématique, mais également à la lumière du concept de chronotope bakhtinien. L’étude classique de Franco Moretti (2000 a toutefois initié un « tournant géographique » à son propos, qu’il semble utile de prolonger en confrontant ses apports à l’analyse chronotopique. En premier lieu, il importe de sortir d’une description globale du roman pour s’approcher au plus près de la dynamique même d’un récit singulier (rythme de l’histoire, parcours et rencontres des personnages dans l’espace. On essayera aussi d’indiquer ce que la cartographie apporte à une lecture attentive du roman. En quoi et comment la production et la visualisation par les cartes génèrent-elles un savoir neuf, impensé et impensable par l’analyse chronotopique ? L’article suit ce double programme en prenant pour objet Les Mystères de Bruxelles (1845-1846 de Suau de Varennes, roman urbain exhumé de l’oubli qui relève des multiples imitations des Mystères de Paris. On verra ainsi que la cartographie permet de réévaluer une œuvre méconnue, tout en indiquant, sur le plan méthodologique, quelques pistes fécondes de la rencontre entre l’histoire sociale, l’histoire littéraire et la géographie urbaine.

  3. Role of Solvents in Improvement of Dissolution Rate of Drugs: Crystal Habit and Crystal Agglomeration

    Directory of Open Access Journals (Sweden)

    Maryam Maghsoodi

    2015-03-01

    Full Text Available Crystallization is often used for manufacturing drug substances. Advances of crystallization have achieved control over drug identity and purity, but control over the physical form remains poor. This review discusses the influence of solvents used in crystallization process on crystal habit and agglomeration of crystals with potential implication for dissolution. According to literature it has been known that habit modification of crystals by use of proper solvents may enhance the dissolution properties by changing the size, number and the nature of crystal faces exposed to the dissolution medium. Also, the faster dissolution rate of drug from the agglomerates of crystals compared with the single crystals may be related to porous structure of the agglomerates and consequently their better wettability. It is concluded from this review that in-depth understanding of role of the solvents in crystallization process can be applied to engineering of crystal habit or crystal agglomeration, and predictably dissolution improvement in poorly soluble drugs.

  4. THERMODYNAMIC REASONS OF AGGLOMERATION OF DUST PARTICLES IN THE THERMAL DUSTY PLASMA

    Directory of Open Access Journals (Sweden)

    V.I.Vishnyakov

    2003-01-01

    Full Text Available The thermodynamic equilibrium of thermal dusty plasmas consisting of ionized gas (plasma and solid particles (dust grains, which interact with each other, is studied. The tendency of grains in dusty plasmas to agglomerate corresponds to the tendency of dusty plasmas to balanced states. When grains agglomerate, electrical perturbations generated by each grain concentrate inside the agglomerate. The plasma is perturbed only by the agglomerate's exterior surface. The greater number of possible states for electrons and ions in plasma depends on the volume of perturbation of grains. The fewer are the perturbations the greater is the amount of possible states for electrons and ions in plasma. If the grains collected from a distance smaller than 8 Debye lengths, the total volume of perturbations is minimized; the free energy of the plasma is also minimized.

  5. Spatial Welfare Economics versus Ecological Footprint: Modeling Agglomeration, Externalities and Trade

    NARCIS (Netherlands)

    Grazi, F.; van den Bergh, J.C.J.M.; Rietveld, P.

    2007-01-01

    A welfare framework for the analysis of the spatial dimensions of sustainability is developed. It covers agglomeration effects, interregional trade, negative environmental externalities, and various land use categories. The model is used to compare rankings of spatial configurations according to

  6. Impact of traffic routes on the content of trace elements in soils in Warsaw agglomeration

    National Research Council Canada - National Science Library

    Artur Komorowski; Wiesław Szulc

    2017-01-01

    ...) in soils near the main traffic routes of the Warsaw agglomeration. The aim of the study was to determine the extent of soil contamination with trace metals at different distances from the road...

  7. A la recherche d'une mutualisation des livraisons en milieu urbain: le cas du groupe NMPP

    OpenAIRE

    Gonzalez-Feliu, Jesus; Morana, Joelle

    2010-01-01

    National audience; La mutualisation des flux de transport est un sujet très populaire mais encore peu exploré. En milieu urbain, une mutualisation des flux de transport permet une meilleure rationalisation des moyens mis en place se traduisant à la fois par une réduction de coût et un impact environnemental moindre. Elle s'avère une alternative pour le secteur de la messagerie de presse, qui en France rencontre de plus en plus de difficultés à réduire ses coûts de distribution. Dans ce contex...

  8. Diversité végétale urbaine et estimation du stock de carbone : cas ...

    African Journals Online (AJOL)

    La réduction du dioxyde de carbone par les arbres est un important service écosystémique pour le bien-être humain. Dans les milieux urbains, ce processus est souvent négligé ou mal connu. La présente étude, réalisée au Plateau, à Abidjan, a permis d'évaluer la diversité des espèces végétales et le taux de carbone ...

  9. Pollution et lutte contre la pollution urbaine en Europe aux XIXe et XXe siècles

    OpenAIRE

    2008-01-01

    Rencontres internationales pour une histoire de l'environnement Premières journées, Clermont-Ferrand, 4, 5 et 6 mai 2000 POLLUTION ET LUTTE CONTRE LA POLLUTION URBAINE EN EUROPE AUX XIXe et XXe SIÈCLES   Programme     Jeudi 4 mai 2000 14h00 : Ouverture des Rencontres Christoph BERNHARDT et Geneviève MASSARD-GUILBAUD, organisateurs Bernard DOMPNIER, directeur du Centre d'histoire " Espaces et cultures " Jean-Luc FRAY, directeur de la Maison de la recherche1ère séance : L'invention d'u...

  10. Évaluation de l'efficacité de l'amélioration du milieu urbain dans la ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    d'examiner si les investissements dans l'amélioration du milieu urbain peuvent se traduire par des progrès sur le plan de la santé, en ce qui a trait par exemple au VIH, à la tuberculose, à la diarrhée et aux problèmes de santé mentale. Le projet se fonde sur l'approche de santé publique relative à la prévention de la ...

  11. Lafargue de Grangeneuve Loïc, Politique du hip-hop. Action publique et cultures urbaines

    Directory of Open Access Journals (Sweden)

    Emmanuel Négrier

    2010-11-01

    Full Text Available L’ouvrage de Loïc Lafargue de Grangeneuve s’inscrit dans une recherche amorcée dans le cadre de sa thèse, qui portait sur les processus d’institutionnalisation des cultures urbaines dans le champ des politiques culturelles. Son travail est centré sur l’interaction entre, d’une part, les représentants de la culture hip-hop (rap, slam, danse hip-hop, graffiti… et d’autre part les institutions publiques : directions régionales des affaires culturelles (DRAC, responsables de la politique de la ...

  12. Enjeux de genre et politiques urbaines : les enseignements d’une recherche à Aubervilliers (Seine-Saint-Denis)

    OpenAIRE

    Blanchard, Sophie; Hancock, Claire

    2017-01-01

    Un travail de recherche conduit en partenariat avec la mairie d’Aubervilliers permet d’éclairer un contexte spécifique, local et institutionnel, dans lequel les enjeux de genre sont pris en compte dans les politiques urbaines, dans une commune très largement concernée par la Politique de la Ville. Parfois dépeinte comme ville dont l’espace est largement dominé par les hommes, la commune d’Aubervilliers œuvre à instaurer la mixité dans ses équipements jeunesse et sport. Une enquête conduite av...

  13. Simulation of deterministic energy-balance particle agglomeration in turbulent liquid-solid flows

    Science.gov (United States)

    Njobuenwu, Derrick O.; Fairweather, Michael

    2017-08-01

    An efficient technique to simulate turbulent particle-laden flow at high mass loadings within the four-way coupled simulation regime is presented. The technique implements large-eddy simulation, discrete particle simulation, a deterministic treatment of inter-particle collisions, and an energy-balanced particle agglomeration model. The algorithm to detect inter-particle collisions is such that the computational costs scale linearly with the number of particles present in the computational domain. On detection of a collision, particle agglomeration is tested based on the pre-collision kinetic energy, restitution coefficient, and van der Waals' interactions. The performance of the technique developed is tested by performing parametric studies on the influence of the restitution coefficient (en = 0.2, 0.4, 0.6, and 0.8), particle size (dp = 60, 120, 200, and 316 μm), Reynolds number (Reτ = 150, 300, and 590), and particle concentration (αp = 5.0 × 10-4, 1.0 × 10-3, and 5.0 × 10-3) on particle-particle interaction events (collision and agglomeration). The results demonstrate that the collision frequency shows a linear dependency on the restitution coefficient, while the agglomeration rate shows an inverse dependence. Collisions among smaller particles are more frequent and efficient in forming agglomerates than those of coarser particles. The particle-particle interaction events show a strong dependency on the shear Reynolds number Reτ, while increasing the particle concentration effectively enhances particle collision and agglomeration whilst having only a minor influence on the agglomeration rate. Overall, the sensitivity of the particle-particle interaction events to the selected simulation parameters is found to influence the population and distribution of the primary particles and agglomerates formed.

  14. Cell agglomeration in the wells of a 24-well plate using acoustic streaming.

    Science.gov (United States)

    Kurashina, Yuta; Takemura, Kenjiro; Friend, James

    2017-02-28

    Cell agglomeration is essential both to the success of drug testing and to the development of tissue engineering. Here, a MHz-order acoustic wave is used to generate acoustic streaming in the wells of a 24-well plate to drive particle and cell agglomeration. Acoustic streaming is known to manipulate particles in microfluidic devices, and even provide concentration in sessile droplets, but concentration of particles or cells in individual wells has never been shown, principally due to the drag present along the periphery of the fluid in such a well. The agglomeration time for a range of particle sizes suggests that shear-induced migration plays an important role in the agglomeration process. Particles with a diameter of 45 μm agglomerated into a suspended pellet under exposure to 2.134 MHz acoustic waves at 1.5 W in 30 s. Additionally, BT-474 cells also agglomerated as adherent masses at the center bottom of the wells of tissue-culture treated 24-well plates. By switching to low cell binding 24-well plates, the BT-474 cells formed suspended agglomerations that appeared to be spheroids, fully fifteen times larger than any cell agglomerates without the acoustic streaming. In either case, the viability and proliferation of the cells were maintained despite acoustic irradiation and streaming. Intermittent excitation was effective in avoiding temperature excursions, consuming only 75 mW per well on average, presenting a convenient means to form fully three-dimensional cellular masses potentially useful for tissue, cancer, and drug research.

  15. How agglomeration in the financial services industry influences economic growth: Evidence from Chinese cities

    OpenAIRE

    Liang, Lin; Lin, Shanglang; Li, Yong

    2014-01-01

    This paper empirically tests the effect of financial knowledge spillovers on agglomeration in China's financial services industry and examines the external effects on cities' economies. The authors apply hierarchical linear modeling to examine a data set that comprises 276 Chinese cities and draw the following conclusions. Firstly, they find that agglomeration in the financial services industry and the Jacobs spillovers of industry diversification both promote financial knowledge spillovers i...

  16. Interaction of magnetite with soluble silicates and bentonite:implications for wet agglomeration of magnetite concentrate

    OpenAIRE

    Yang, Xiaofang

    2011-01-01

    Iron ore green pellets are produced by agglomeration of moist magnetite concentrates. The quality of green pellets is essential for the transportability and metallurgical benefits of the final product. The agglomeration behavior of magnetite concentrate particles is strongly influenced by its surface properties which are affected by the interactions with flotation reagents (i.e. water glass and collector) and species in process water. However, the mechanisms of these interactions and the infl...

  17. Analysis of nanoparticle agglomeration in aqueous suspensions via constant-number Monte Carlo simulation.

    Science.gov (United States)

    Liu, Haoyang Haven; Surawanvijit, Sirikarn; Rallo, Robert; Orkoulas, Gerassimos; Cohen, Yoram

    2011-11-01

    A constant-number direct simulation Monte Carlo (DSMC) model was developed for the analysis of nanoparticle (NP) agglomeration in aqueous suspensions. The modeling approach, based on the "particles in a box" simulation method, considered both particle agglomeration and gravitational settling. Particle-particle agglomeration probability was determined based on the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and considerations of the collision frequency as impacted by Brownian motion. Model predictions were in reasonable agreement with respect to the particle size distribution and average agglomerate size when compared with dynamic light scattering (DLS) measurements for aqueous TiO(2), CeO(2), and C(60) nanoparticle suspensions over a wide range of pH (3-10) and ionic strength (0.01-156 mM). Simulations also demonstrated, in quantitative agreement with DLS measurements, that nanoparticle agglomerate size increased both with ionic strength and as the solution pH approached the isoelectric point (IEP). The present work suggests that the DSMC modeling approach, along with future use of an extended DLVO theory, has the potential for becoming a practical environmental analysis tool for predicting the agglomeration behavior of aqueous nanoparticle suspensions.

  18. Combined deterministic-stochastic framework for modeling the agglomeration of colloidal particles.

    Science.gov (United States)

    Mortuza, S M; Kariyawasam, Lahiru K; Banerjee, Soumik

    2015-07-01

    We present a multiscale model, based on molecular dynamics (MD) and kinetic Monte Carlo (kMC), to study the aggregation driven growth of colloidal particles. Coarse-grained molecular dynamics (CGMD) simulations are employed to detect key agglomeration events and calculate the corresponding rate constants. The kMC simulations employ these rate constants in a stochastic framework to track the growth of the agglomerates over longer time scales and length scales. One of the hallmarks of the model is a unique methodology to detect and characterize agglomeration events. The model accounts for individual cluster-scale effects such as change in size due to aggregation as well as local molecular-scale effects such as changes in the number of neighbors of each molecule in a colloidal cluster. Such definition of agglomeration events allows us to grow the cluster to sizes that are inaccessible to molecular simulations as well as track the shape of the growing cluster. A well-studied system, comprising fullerenes in NaCl electrolyte solution, was simulated to validate the model. Under the simulated conditions, the agglomeration process evolves from a diffusion limited cluster aggregation (DLCA) regime to percolating cluster in transition and finally to a gelation regime. Overall the data from the multiscale numerical model shows good agreement with existing theory of colloidal particle growth. Although in the present study we validated our model by specifically simulating fullerene agglomeration in electrolyte solution, the model is versatile and can be applied to a wide range of colloidal systems.

  19. Laser-induced agglomeration of gold nanoparticles dispersed in a liquid

    Energy Technology Data Exchange (ETDEWEB)

    Serkov, A.A.; Shcherbina, M.E. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, Moscow Institute of Physics and Technology (State University), Moscow (Russian Federation); Kuzmin, P.G., E-mail: qzzzma@gmail.com [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Kirichenko, N.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, Moscow Institute of Physics and Technology (State University), Moscow (Russian Federation)

    2015-05-01

    Highlights: • Pulsed laser irradiation of dense gold nanoparticles colloidal solution can result in their agglomeration. • Gas bubbles in-phase pulsation induced by laser radiation accounts for nanoparticles agglomeration. • Time evolution of the size distribution function proceeds in activation mode. • The electrostatic-like model of nanoparticles agglomeration is in good correspondence with the experimental data. - Abstract: Dynamics of gold nanoparticles (NPs) ensemble in dense aqueous solution under exposure to picosecond laser radiation is studied both experimentally and theoretically. Properties of NPs are examined by means of transmission electron microscopy, optical spectroscopy, and size-measuring disk centrifuge. Theoretical investigation of NPs ensemble behavior is based on the analytical model taking into account collisions and agglomeration of particles. It is shown that in case of dense NPs colloidal solutions (above 10{sup 14} particles per milliliter) the process of laser fragmentation typical for nanosecond laser exposure turns into laser-induced agglomeration which leads to formation of the particles with larger sizes. It is shown that there is a critical concentration of NPs: at higher concentrations agglomeration rate increases tremendously. The results of mathematical simulation are in compliance with experimental data.

  20. The agglomeration state of nanoparticles can influence the mechanism of their cellular internalisation.

    Science.gov (United States)

    Halamoda-Kenzaoui, Blanka; Ceridono, Mara; Urbán, Patricia; Bogni, Alessia; Ponti, Jessica; Gioria, Sabrina; Kinsner-Ovaskainen, Agnieszka

    2017-06-26

    Significant progress of nanotechnology, including in particular biomedical and pharmaceutical applications, has resulted in a high number of studies describing the biological effects of nanomaterials. Moreover, a determination of so-called "critical quality attributes", that is specific physicochemical properties of nanomaterials triggering the observed biological response, has been recognised as crucial for the evaluation and design of novel safe and efficacious therapeutics. In the context of in vitro studies, a thorough physicochemical characterisation of nanoparticles (NPs), also in the biological medium, is necessary to allow a correlation with a cellular response. Following this concept, we examined whether the main and frequently reported characteristics of NPs such as size and the agglomeration state can influence the level and the mechanism of NP cellular internalization. We employed fluorescently-labelled 30 and 80 nm silicon dioxide NPs, both in agglomerated and non-agglomerated form. Using flow cytometry, transmission electron microscopy, the inhibitors of endocytosis and gene silencing we determined the most probable routes of cellular uptake for each form of tested silica NPs. We observed differences in cellular uptake depending on the size and the agglomeration state of NPs. Caveolae-mediated endocytosis was implicated particularly in the internalisation of well dispersed silica NPs but with an increase of the agglomeration state of NPs a combination of endocytic pathways with a predominant role of macropinocytosis was noted. We demonstrated that the agglomeration state of NPs is an important factor influencing the level of cell uptake and the mechanism of endocytosis of silica NPs.

  1. Developmental research study of coal-fines agglomeration for fixed-bed gasification. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Elmquist, S.A.; Girimont, J.A.; Korosi, F.A.; Kuby, O.A.; Nelson, S.G.; Paulin, M.O.; Peterson, C.A.; Baker, R.L.; Saller, E.

    1983-05-31

    This report presents the results of an intensive program to develop and evaluate agglomerates made from coal fines for use in a fixed-bed gasifier. There were several tasks completed earlier and their results published prior to this final report. These included: Task 1-A, a literature survey of coal agglomeration, binders and techniques used in coal agglomeration, coal and binder treatments and the results of work done by others; Task 1-B, an examination of performance of lump coals in coal gasification, testing and evaluation of the properties of these coals, and evaluation of mine site coal upgrading methods; and Task 1-C/D, a laboratory investigation of coal agglomerates, including wafers, briquettes and pellets, in which the agglomerated coal fines were formed and tested, and the performance of various coal/binder combinations was recorded and evaluated, and factors affecting commercial scale coal agglomeration and gasification were evaluated. These three prior tasks are presented in this report in condensed form.

  2. Study on the Policy Factors of Innovative Talents Agglomeration in Jiangsu Province based on Data Analysis

    Directory of Open Access Journals (Sweden)

    Li Wenfei

    2016-03-01

    Full Text Available Innovative talent is the key factor to promote the development of innovative economy and realize innovative drive in Jiangsu Province. Innovative talent agglomeration can fully play the effect of innovative talents through the agglomeration efficiency. Among many factors that affect the agglomeration of innovative talents, the guiding role of government policy factors is becoming more and more important. Based on the survey of domestic and foreign literature, through questionnaire survey, this paper combines relevant analysis and regression analysis to study the mechanism between the of scientific research funds investment, household registration policy, outstanding achievement award and patent licensing and the innovative talent agglomeration. The results show that the investment of scientific research funds, the household registration policy, the outstanding achievement award and the patent authorization have remarkable influence on the innovation talent agglomeration. The conclusion of this study not only expands the theoretical research field of government policy and innovative talent agglomeration, but also provides practical guidance for the government of Jiangsu Province in the era of innovation knowledge.

  3. Factors affecting the oil agglomeration of Sivas-Divrigi Ulucayir lignite

    Energy Technology Data Exchange (ETDEWEB)

    Unal, I.; Gorgun Ersan, M. [Cumhuriyet University, Sivas (Turkey)

    2007-07-01

    In the coal industry, the coal particles need to be decreased to a very fine size because of the need of removing inorganic materials from coal. Oil agglomeration is a kind of coal cleaning technique that is used for separation of organic and inorganic parts of fine sized coal. In this study, the oil agglomeration of Sivas-Divrigi (S-D) Ulucayir lignite was carried out by using kerosene, diesel oil, fuel oil, poppy oil, and sunflower oil. The amount of bridging oil was varied from 5% to 25% of the amount of lignite. The effect of oil amount, oil type, solid content, agitation rate and time, pH on agglomeration performance was investigated. Maximum recovery value of 98.18% was observed by using poppy oil. In order to investigate the effect of pH on agglomeration NaOH and HCl is added to the slurry in various amounts. It is decided that the best agglomeration condition is obtained at low pH values. The effect of nonionic surface active agent (Igepal-CA 630) on agglomeration is investigated by adding to the slurry and it is observed that the grade is increased with the amount of surface active agent.

  4. An analysis of precipitation climatology over Indian urban agglomeration

    Science.gov (United States)

    Bisht, Deepak Singh; Chatterjee, Chandranath; Raghuwanshi, Narendra Singh; Sridhar, Venkataramana

    2017-06-01

    While urban areas in India are rapidly expanding, the analysis of how the precipitation regimes are changing is very limited. In the present study, an attempt has been made to explore the trends in rainfall pattern over 20 most populated urban agglomeration (cities) of India using high resolution gridded, daily rainfall product (0.25° × 0.25°) obtained from India Meteorological Department (IMD). The analysis comprised of annual and monsoonal rainfall and rainy days; 1- and 10-day annual maximum rainfall; 95 and 99 percentile extreme threshold rainfall magnitude in 30 years moving window; and number of events above 95 and 99 percentile threshold in each year during 1901-2015. The Mann-Kendall (Modified Mann-Kendall) test at 0.1 significance level to detect trends, and the Thiel-Sen's approach to estimate % change over mean have been used. Annual and monsoonal rainfall are found to be increasing with shrinking rainy days during the same period that infers rise in heavy rainfall events. Besides, the majority of the cities show increasing trends in 1- and 10-day annual maximum rainfall, number of extreme threshold events, and magnitude of extreme threshold rainfall in 30-year moving window. The Pettitt-Mann-Whitney (PMW) test was used to detect change point year. Cities with significant change point at probability level ≥90% were selected to analyze pre- and post-change point year trend in time series. In addition, the trend in precipitation variables for multiple climatic windows of 30 years with an advancement of 5 years in each window (1901-1930, 1906-1935 …, 1986-2015) show that unlike a unique long-term trend, different climatic windows have varying trend direction over the period of time. Overall, the analysis reveals the rising trend in extreme rainfall events over majority of the cities in long term (1901-2015); however, mixed pattern of trends are observed in moving climatic windows.

  5. Has the kouprey (Bos sauveli Urbain, 1937) been domesticated in Cambodia?

    Science.gov (United States)

    Hassanin, Alexandre; Ropiquet, Anne; Cornette, Raphaël; Tranier, Michel; Pfeffer, Pierre; Candegabe, Philippe; Lemaire, Michèle

    2006-02-01

    The kouprey (Bos sauveli Urbain, 1937) is a very rare bovid species of Cambodia, which may be extinct in the wild, as no living specimen has been observed for a long time. Here, we describe a complete taxidermy mount, which presents astonishing morphological similarities with the kouprey. The animal was mounted in 1871 at the National Museum of Natural History in Paris, where it was referenced as No. 1871-576. It was deposited at the Natural History Museum of Bourges, France, in 1931, where it is still conserved today. To clarify the taxonomic status of the specimen of Bourges, DNA was extracted from a piece of bone taken on the mandible, and two different fragments of the mitochondrial cytochrome b gene were independently amplified and sequenced. The phylogenetic analyses show that the specimen of Bourges is robustly associated with the holotype of the kouprey, and that both are related to other wild species of Bos found in Indochina, i.e., banteng (B. javanicus) and gaur (B. frontalis). Because of doubts for sexing the animal, we applied a molecular test based on the PCR amplification of a DNA fragment specific to the Y chromosome. The results indicate that the specimen of Bourges is a male. The comparisons with male kouprey previously described in the literature reveal important differences concerning the body size, general coloration and horns. As these differences involve phenotypic traits that are strongly selected in case of domestication, we suggest that the specimen of Bourges was a domestic ox. This implies therefore that the kouprey may have been domesticated in Cambodia, and that several extant local races may be directly related to the kouprey.

  6. Qualité de l’offre et usage du transport public en milieu urbain

    Directory of Open Access Journals (Sweden)

    Cyrille Genre-Grandpierre

    2007-06-01

    Full Text Available L’objectif de ce travail est de mieux cerner les déterminants de la mobilité quotidienne en bus en milieu urbain. Il s’agit en particulier d’étudier dans quelle mesure la qualité de l’offre de transport en bus en détermine l’intensité de l’usage. Une première étape a consisté à élaborer un indicateur décrivant localement la qualité de l’accessibilité fournie par le bus. Dans un second temps, des données originales portant sur les déplacements quotidiens à Besançon ont été collectées grâce à une enquête téléphonique, puis implémentées dans un Système d’Information Géographique. Dans un troisième temps, la mise en relation de l’offre et de l’usage du bus a permis de montrer que la qualité de l’offre bus n’en explique l’usage qu’à un niveau très agrégé, mais qu’elle explique en revanche bien la satisfaction quant à cet usage. Plutôt qu’à travers une estimation globale de la qualité de l’offre bus, il est apparu que ce n’est que dans la comparaison de l’offre bus et de l’offre automobile sur un ensemble d’origines-destinations bien précis que l’on parvenait à comprendre les ressorts du choix modal.

  7. Biomass equipments. Dryers. Drying, crushing, agglomeration of agro-industrial products; Materiels pour la biomasse. Les secheurs, sechage, broyage, agglomeration de produits agro-industriels

    Energy Technology Data Exchange (ETDEWEB)

    Deur, O. [Promill (France)

    1997-12-31

    This paper describes the French Promill Company activity in the design and manufacturing of complete drying-crushing-agglomerating units for agro-industrial products (pulp of beet, lucerne, etc..). The paper focusses on the thermal and mechanical efficiency of the high temperature dryer and on the pulp granulating squeezer. (J.S.)

  8. Le peuplement, catégorie montante des politiques urbaines néolibérales ?

    Directory of Open Access Journals (Sweden)

    Christelle Morel Journel

    2012-05-01

    Full Text Available Cet article se propose de considérer le « peuplement » comme nouvel enjeu stratégique pour les villes, dans un contexte de néolibéralisation des politiques urbaines et de montée en puissance de l’entrepreneurialisme urbain. La volonté de contrôler ou d’agir sur l’occupation sociale des espaces urbains, d’influencer les mobilités résidentielles, n’est pas nouvelle mais les stratégies de gentrification en constitueraient aujourd’hui la principale traduction. Les analyses défendant l’hybridité des politiques urbaines contemporaines, articulant des éléments de restructuration néolibérale et des héritages politiques et institutionnels – nationaux et locaux – de l’ère fordiste, permettent de mieux saisir la complexité des enjeux de peuplement, pris entre les logiques de la « place » et celles du « territoire ». Le cas de Saint-Etienne, ville moyenne dont l’histoire récente est marquée par la désindustrialisation et une décroissance démographique significative (près de 50 000 habitants ont quitté la ville depuis 1968, illustre l’imposition du paradigme de l’attractivité dans les politiques urbaines. En effet, au début des années 2000, la Ville a mis en œuvre une stratégie spécifique sur l’habitat alors que le laisser-faire l’emportait dans la période précédente. Cependant, cette stratégie ne repose pas sur une logique unidimensionnelle de gentrification mais sur une logique hybride mêlant une réelle préoccupation pour les – ou certains des – habitants « déjà là » et des enjeux d’image et d’attractivité à l’égard de l’extérieur, et notamment à une échelle intercommunale.This paper suggests regarding « populating » as a new key issue for cities, in the context of neoliberalisation of urban policies and the rise of urban entrepreneurialism. Within this context, it seems as if gentrification strategies were the main translation of the ancient

  9. Optimization of experimental conditions for recovery of coking coal fines by oil agglomeration technique

    Energy Technology Data Exchange (ETDEWEB)

    G.H.V.C. Chary; M.G. Dastidar [Indian Institute of Technology Delhi, New Delhi (India). Centre for Energy Studies

    2010-09-15

    The significance of coking coal in the metallurgical sector as well as the meager coking coal reserves across the globe increase the necessity to recover coking coal fines from the fine coking coal slurries generated from coal preparation and utilization activities. Oil agglomeration studies were carried out by varying the experimental conditions for maximum recovery of coking coal fines i.e., yield of the agglomerates. The various operational parameters studied were oil dosage, agitation speed, agglomeration time and pulp density. By using Taguchi experimental design, oil dosage (20%), agitation speed (1100 rpm), agglomeration time (3 min) and pulp density (4.5%) were identified as the optimized conditions. A confirmation experiment has also been carried out at the optimized conditions. The percentage contribution of each parameter on agglomerate yield was analyzed by adopting analysis of variance (ANOVA) statistical method as well as multiple linear regression analysis. The order of influence of the parameters on the agglomerate yield is of the following order: pulp density {lt} oil dosage {lt} agitation speed {gt} agglomeration time. A mathematical model was developed to fit the set of experimental condition with the yield obtained at each test run and also at the optimized conditions. The experimentally obtained yield was compared with the predicted yield of the model and the results indicate a maximum error of 5% between the two. A maximum yield of 90.42% predicted at the optimized conditions appeared to be in close agreement with the experimental yield thus indicating the accuracy of the model in predicting the results. 12 refs., 4 figs., 11 tabs.

  10. Characterizing Nanoparticles in Biological Matrices: Tipping Points in Agglomeration State and Cellular Delivery In Vitro.

    Science.gov (United States)

    Wills, John W; Summers, Huw D; Hondow, Nicole; Sooresh, Aishwarya; Meissner, Kenith E; White, Paul A; Rees, Paul; Brown, Andy; Doak, Shareen H

    2017-11-01

    Understanding the delivered cellular dose of nanoparticles is imperative in nanomedicine and nanosafety, yet is known to be extremely complex because of multiple interactions between nanoparticles, their environment, and the cells. Here, we use 3-D reconstruction of agglomerates preserved by cryogenic snapshot sampling and imaged by electron microscopy to quantify the "bioavailable dose" that is presented at the cell surface and formed by the process of individual nanoparticle sequestration into agglomerates in the exposure media. Critically, using 20 and 40 nm carboxylated polystyrene-latex and 16 and 85 nm silicon dioxide nanoparticles, we show that abrupt, dose-dependent "tipping points" in agglomeration state can arise, subsequently affecting cellular delivery and increasing toxicity. These changes are triggered by shifts in the ratio of the total nanoparticle surface area to biomolecule abundance, with the switch to a highly agglomerated state effectively changing the test article midassay, challenging the dose-response paradigm for nanosafety experiments. By characterizing nanoparticle numbers per agglomerate, we show these tipping points can lead to the formation of extreme agglomeration states whereby 90% of an administered dose is contained and delivered to the cells by just the top 2% of the largest agglomerates. We thus demonstrate precise definition, description, and comparison of the nanoparticle dose formed in different experimental environments and show that this description is critical to understanding cellular delivery and toxicity. We further empirically "stress-test" the commonly used dynamic light scattering approach, establishing its limitations to present an analysis strategy that significantly improves the usefulness of this popular nanoparticle characterization technique.

  11. Combustion of single and agglomerated aluminum particles in solid rocket motor flows

    Science.gov (United States)

    Melcher, John Charles, IV

    2001-07-01

    Single and agglomerated aluminum droplets were studied in a solid rocket motor (SRM) test chamber with optical access to the internal flow at 6--22 atm and 2300 K. The chamber was pressurized by burning a main grain AP/HTPB propellant, and the burning aluminum droplets were generated by a smaller aluminized solid propellant sample, center-mounted in the flow. A 35 mm camera was used with a chopper wheel to give droplet flame diameter vs. time measurements of the burning droplets in flight, from which bum-rate laws were developed. A high-speed video CCD was used with high-magnification optics in order to image the flame/smoke cloud surrounding the burning liquid droplets. The intensity profiles of the droplet images were de-convoluted using an Abel inversion to give true intensity profiles. Both single and agglomerated droplets were studied, where agglomerates are comprised of hundreds of parent particles or more. The Abel inversion results show that the relative smoke cloud size is not constant with diameter, but instead grows as the droplet shrinks, by ˜D -0.5, for both the single and agglomerated droplets. Measured diameter trajectories show that for single droplets, the diameter law is D 0.75 = DO0.75 = 8·t [mu m, msec], and for agglomerated droplets, D 1.0 = Do1.0 - 20·t, such that the single droplets burn faster than the agglomerates. For both single and agglomerated droplets, the burning rate slope k did not change significantly over the chamber pressure studied. Lastly, a model was developed to describe the oxide cap accumulation on the droplet surface from the oxide smoke cloud surrounding the droplet. Results suggest that less oxide accumulates in high-pressure SRMs when considering mass burning rates for different relative cap sizes. The thermophoretic force, which can control oxide transport only over the cap, decreases with pressure.

  12. h-multigrid agglomeration based solution strategies for discontinuous Galerkin discretizations of incompressible flow problems

    Science.gov (United States)

    Botti, L.; Colombo, A.; Bassi, F.

    2017-10-01

    In this work we exploit agglomeration based h-multigrid preconditioners to speed-up the iterative solution of discontinuous Galerkin discretizations of the Stokes and Navier-Stokes equations. As a distinctive feature h-coarsened mesh sequences are generated by recursive agglomeration of a fine grid, admitting arbitrarily unstructured grids of complex domains, and agglomeration based discontinuous Galerkin discretizations are employed to deal with agglomerated elements of coarse levels. Both the expense of building coarse grid operators and the performance of the resulting multigrid iteration are investigated. For the sake of efficiency coarse grid operators are inherited through element-by-element L2 projections, avoiding the cost of numerical integration over agglomerated elements. Specific care is devoted to the projection of viscous terms discretized by means of the BR2 dG method. We demonstrate that enforcing the correct amount of stabilization on coarse grids levels is mandatory for achieving uniform convergence with respect to the number of levels. The numerical solution of steady and unsteady, linear and non-linear problems is considered tackling challenging 2D test cases and 3D real life computations on parallel architectures. Significant execution time gains are documented.

  13. Temperature-Switchable Agglomeration of Magnetic Particles Designed for Continuous Separation Processes in Biotechnology.

    Science.gov (United States)

    Paulus, Anja S; Heinzler, Raphael; Ooi, Huey Wen; Franzreb, Matthias

    2015-07-08

    The purpose of this work was the synthesis and characterization of thermally switchable magnetic particles for use in biotechnological applications such as protein purification and enzymatic conversions. Reversible addition-fragmentation chain-transfer polymerization was employed to synthesize poly(N-isopropylacrylamide) brushes via a "graft-from" approach on the surface of magnetic microparticles. The resulting particles were characterized by infrared spectroscopy and thermogravimetric analysis and their temperature-dependent agglomeration behavior was assessed. The influence of several factors on particle agglomeration (pH, temperature, salt type, and particle concentration) was evaluated. The results showed that a low pH value (pH 3-4), a kosmotropic salt (ammonium sulfate), and a high particle concentration (4 g/L) resulted in improved agglomeration at elevated temperature (40 °C). Recycling of particles and reversibility of the temperature-switchable agglomeration were successfully demonstrated for ten heating-cooling cycles. Additionally, enhanced magnetic separation was observed for the modified particles. Ionic monomers were integrated into the polymer chain to create end-group functionalized particles as well as two- and three-block copolymer particles for protein binding. The adsorption of lactoferrin, bovine serum albumin, and lysozyme to these ion exchange particles was evaluated and showed a binding capacity of up to 135 mg/g. The dual-responsive particles combined magnetic and thermoresponsive properties for switchable agglomeration, easy separability, and efficient protein adsorption.

  14. Agglomeration during wet milling of LAST (lead-antimony-silver-tellurium) powders

    Energy Technology Data Exchange (ETDEWEB)

    Hall, B.D. [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Case, E.D. [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States)], E-mail: casee@egr.msu.edu; Ren, F.; Johnson, J.R. [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Timm, E.J. [Mechanical Engineering Department, Michigan State University, East Lansing, MI 48824 (United States)

    2009-01-15

    LAST (lead-antimony-silver-tellurium) compounds comprise a family of semiconducting materials with good thermoelectric properties. However, the as-cast form of LAST exhibits large grain size and hence low mechanical strength. Powder processing can produce a fine powder particle size that enhances fracture strength, however the powders tend to agglomerate if the individual powder diameters are less than a few microns across. Dry milling or wet milling (hexane additions of 0 cm{sup 3} and 10 cm{sup 3}) produced hard agglomerates roughly 40 {mu}m in diameter while wet milling with hexane additions of 25 cm{sup 3}, 30 cm{sup 3} or 50 cm{sup 3} resulted in small, porous agglomerates roughly 20 {mu}m in diameter. Thus, by adjusting the amount of milling liquid used while milling LAST powders, one can shift from hard to soft agglomerates, where the literature shows that soft agglomerates are less harmful to the final, sintered product. Also, in agreement with the results from the literature on other materials, wet milling of LAST powders produced smaller particle sizes but required longer times to reach the grindability limit.

  15. Folate-Binding Protein Self-Aggregation Drives Agglomeration of Folic Acid Targeted Iron Oxide Nanoparticles.

    Science.gov (United States)

    Chen, Junjie; Klem, Sarah; Jones, Alexis K; Orr, Bradford; Banaszak Holl, Mark M

    2017-01-18

    Folate-conjugated nanomaterials have been widely investigated for drug and imaging-agent delivery. In this work, two folic acid (FA) conjugated iron oxide particles (IOP), a ∼40 nm diameter FA-IOP and a ∼450 nm diameter FA-IOP(FA-SeraMag), were synthesized. Both particles aggregated in the presence of serum folate-binding protein (FBP) at physiological concentration and buffer conditions. Mixing 0.01% w/w FA-conjugated iron oxide particles with FBP-induced agglomeration generated an average hydrodynamic particle diameter of 3800 ± 1100 nm for ∼40 nm FA-IOP and 4030 ± 1100 nm for FA-SeraMag as measured by dynamic light scattering (DLS). The presence of excess human serum albumin (HSA) (600 μM) did not prevent agglomeration of the ∼40 nm FA-IOP; however, it did inhibit agglomeration of FA-SeraMag. Atomic force microscopy measurement provided additional insight into particle morphology with the detection of individual particles in the agglomerate. This behavior is an example of a triggered cascade. A protein structural change is induced by FA binding, and the structural change favors aggregation of the ∼4 nm diameter FBPs on the particle surface; this further triggers the agglomeration of both the ∼40 and ∼450 nm diameter IOPs.

  16. Effect of sample container morphology on agglomeration dynamics of magnetic nanoparticles under magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Dae Seong; Kim, Hack Jin [Dept. of Chemistry, Chungnam National University, Daejeon (Korea, Republic of)

    2016-12-15

    The superparamagnetic magnetite nanoparticles have been used extensively in medical and biological applications, and agglomeration of magnetic nanoparticles is employed in the purification of water and proteins. The magnetic weight can be measured with a conventional electronic balance. Details of the experimental setup have been previously reported. That is, complex energy landscape involved in the agglomeration is changing with progress. Simulation of colloidal magnetic particles under magnetic field shows that the chain of particles is energetically more favorable than the ring and that the transition barrier between the chain and the ring is very low. The energy barriers among entangled nanoparticles of the agglomerate seem to be much more complicated than those among colloidal particles. The energy barrier distributions at 1000 min are similar for the two containers; however, the trend of blue shift and broadening is much more evident in the case of conical tube. These results indicate that the potential energy surface for agglomeration is modified more significantly in the conical tube which makes the agglomerate denser.

  17. Development of standards and a cost model for coal agglomeration and related studies

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, S.G.; Kuby, O.A.; Korosi, F.A.; Paulin, M.O.

    1982-02-26

    Several topics concerning coal agglomeration and fixed-bed coal gasification, as they relate to an agglomeration-process development program presently being performed for the Department of Energy, are discussed in this report. Specific topics include an examination of the performance of coals in fixed-bed gasifiers, the development of properties' standards by which agglomerates produced in the program may be compared, the development of a cost model to judge the economic feasibility of coal agglomeration for potential users and the maximum binder levels to be considered in the program, the definition of a suitable briquette size for coal gasification, and a study of upgrading methods at the mines to improve agglomeration. Extensive property data and the results of a number of special tests on six coals (Pittsburgh No. 8 bituminous coal, Illinois No. 6 bituminous coal, Wyoming Bighorn subbituminous coal, Montana Rosebud No. 14 subbituminous coal, North Dakota Indian Head lignite and Pennsylvania Nanoth anthracite coal) and on FMC formcoke and Simplex briquettes are reported.

  18. Effect of Rubber Nanoparticle Agglomeration on Properties of Thermoplastic Vulcanizates during Dynamic Vulcanization

    Directory of Open Access Journals (Sweden)

    Hanguang Wu

    2016-04-01

    Full Text Available We previously reported that the dispersed rubber microparticles in ethylene-propylene-diene monomer (EPDM/polypropylene (PP thermoplastic vulcanizates (TPVs are actually agglomerates of rubber nanoparticles. In this study, based on this new understanding of the microstructure of TPV, we further revealed the microstructure-properties relationship of EPDM/PP TPV during dynamic vulcanization, especially the effect of the size of rubber nanoparticle agglomerates (dn, the thicknesses of PP ligaments (IDpoly and the rubber network on the properties of EPDM/PP TPV. We were able to simultaneously obtain a high tensile strength, elongation at break, elastic modulus, and elasticity for the EPDM/PP TPV by the achievement of a smaller dn, a thinner IDpoly and a denser rubber network. Interestingly, the effect of dn and IDpoly on the elastic modulus of EPDM/PP TPV composed of rubber nanoparticle agglomerates is different from that of EPDM/PP TPVs composed of rubber microparticles reported previously. The deformation behavior of the TPVs during stretching was studied to understand the mechanism for the achievement of good mechanical properties. Interestingly, the rubber nanoparticle agglomerates are oriented along the tensile direction during stretching. The TPV samples with smaller and more numerous rubber nanoparticle agglomerates can slow down the development of voids and cracks more effectively, thus leading to increase in tensile strength and elongation at break of the EPDM/PP TPV.

  19. Experimental investigation on agglomeration of coal-fired PM10 in uniform magnetic field

    Science.gov (United States)

    Li, Yongwang; Zhao, Changsui; Wu, Xin; Lu, Duanfeng; Han, Song

    2007-06-01

    Agglomeration experiments on fly ash particles in the size range of 0.023-9.314 μm were conducted in a uniform magnetic field. The fly particles were produced from combustion of bituminous coal originated in Dongshen, China. A dedicated fluidized bed aerosol generator was developed to disperse particles to generate aerosol with constant rate. The aerosol particles from the generator underwent agglomeration during passing through the magnetic field. The variation in particles number concentration induced by agglomeration was measured in real time by Electrical Low Pressure Impactor (ELPI). The effects of the particle size, the magnetic flux density, the particle residence time in the magnetic field, the total particle mass concentration and the average gas velocity on particle agglomeration were examined. Experimental results indicate that the removal efficiencies for the midsized particles are higher than those for the smaller and the bigger ones. Single-sized and total particle removal efficiencies can be enhanced by rasing the magnetic flux density, the total particle mass concentration, the particle residence time in the magnetic field or reducing the average gas velocity. When particles are satuatedly magnetized, the magnetic flux density has no effect on their agglomeration.

  20. The surface properties of nanoparticles determine the agglomeration state and the size of the particles under physiological conditions

    National Research Council Canada - National Science Library

    Bantz, C; Koshkina, O; Lang, T; Galla, H.J; Kirkpatrick, C.J; Stauber, R.H; Maskos, M

    2014-01-01

    .... As promising candidates for biomedical applications, two SiO2-based nanomaterial systems were chosen for extensive size characterization to investigate the agglomeration behavior under physiological conditions...

  1. Study of the temperature evolution of defect agglomerates in neutron irradiated molybdenum single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lambri, O.A. [Instituto de Fisica Rosario. Member of the CONICET' s Research Staff, Avda. Pellegrini 250, (2000) Rosario, Santa Fe (Argentina); Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Laboratorio de Materiales, Escuela de Ingenieria Electrica, Avda. Pellegrini 250, (2000) Rosario, Santa Fe (Argentina)], E-mail: olambri@fceia.unr.edu.ar; Zelada-Lambri, G.I. [Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Laboratorio de Materiales, Escuela de Ingenieria Electrica, Avda. Pellegrini 250, (2000) Rosario, Santa Fe (Argentina); Cuello, G.J. [Institut Laue Langevin, 6, rue Jules Horowitz, BP 156, 38042 Grenoble (France); Departamento de Fisica Aplicada II, Facultad de Ciencias y Tecnologia, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao, Pais Vasco (Spain); Bozzano, P.B. [Laboratorio de Microscopia Electronica. Unidad de Actividad Materiales, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Avda. Gral. Paz 1499, (1650) San Martin (Argentina); Garcia, J.A. [Departamento de Fisica Aplicada II, Facultad de Ciencias y Tecnologia, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao, Pais Vasco (Spain)

    2009-04-15

    Small angle neutron scattering as a function of temperature, differential thermal analysis, electrical resistivity and transmission electron microscopy studies have been performed in low rate neutron irradiated single crystalline molybdenum, at room temperature, for checking the evolution of the defects agglomerates in the temperature interval between room temperature and 1200 K. The onset of vacancies mobility was found to happen in temperatures within the stage III of recovery. At around 550 K, the agglomerates of vacancies achieve the largest size, as determined from the Guinier approximation for spherical particles. In addition, the decrease of the vacancy concentration together with the dissolution of the agglomerates at temperatures higher than around 920 K was observed, which produce the release of internal stresses in the structure.

  2. Agglomeration-free preparation of modified silica nanoparticles for emulsion polymerization - a well scalable process.

    Science.gov (United States)

    Hübner, Christian; Fettkenhauer, Christian; Voges, Kevin; Lupascu, Doru Constantin

    2017-12-14

    To prepare modified silica nanospheres for emulsion polymerization a new agglomeration-free change of dispersion media has been developed. Nanosized silicaspheres were synthesized by the Stöber method and directly modified with a silane coupling agent. To prepare these particles for subsequent polymerization the dispersion medium was changed in a twostep process from ethanol to water without agglomeration of the particles. The emulsion polymerization leads to hemispherical single core structured silica-polystyrene composite particles. The thickness of the polymer shell can be altered by varying the amount of styrene. The developed change of dispersion media provides non-agglomerated modified silica particles for the encapsulation with polystyrene and enables the synthesis of narrowly distributed single core composite particles. The developed process is a promising approach for the preparation of nanoparticles for subsequent polymerization and can be scaled up for industrial applications.

  3. A Novel Equivalent Agglomeration Model for Heat Conduction Enhancement in Nanofluids.

    Science.gov (United States)

    Sui, Jize; Zheng, Liancun; Zhang, Xinxin; Chen, Ying; Cheng, Zhengdong

    2016-01-18

    We propose a multilevel equivalent agglomeration (MEA) model in which all particles in an irregular cluster are treated as a new particle with equivalent volume, the liquid molecules wrapping the cluster and in the gaps are considered to assemble on the surface of new particle as mixing nanolayer (MNL), the thermal conductivity in MNL is assumed to satisfy exponential distribution. Theoretical predictions for thermal conductivity enhancement are highly in agreement with the classical experimental data. Also, we first try to employ TEM information quantitatively to offer probable reference agglomeration ratio (not necessary a very precise value) to just test rational estimations range by present model. The comparison results indicate the satisfactory priori agglomeration ratio estimations range from renovated model.

  4. Basic study for the controlling of the dispersion and the agglomeration of magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, H; Hashi, S; Ishiyama, K, E-mail: ishiyama@riec.tohoku.ac.j [Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba 980-8577 (Japan)

    2010-01-01

    The effective way of controlling the dispersion and the agglomeration of the magnetic particles is desired for the medical treatment such as magnetic hyperthermia and drug delivery system using magnetic particles. In this study, we propose the principle of a new method of controlling them. If we use the magnetic particles with magnetic anisotropy, the particles can be rotated by the magnetic torque generated by the rotational magnetic field. When the rotating agglomerated particles are subjected to the fluid pressure, the agglomeration is parted into pieces and dispersed due to the increase of the drug force from the fluid. We found that it is important to control the Coulomb force between the particles by surface coating. As a basic study using the two magnetic particles, we confirmed the condition that the aggregated two small magnets get isolated experimentally with changing the thickness of the coating layer and the rotational frequency.

  5. Research in the Agglomeration Level of Textile Industry in Yangtze River Delta Region of China

    Directory of Open Access Journals (Sweden)

    Zhou Hao

    2017-01-01

    Full Text Available This paper uses the EG index, which adjust accordingly to the textile industry data of Yangtze River Delta region of China to measure the level of textile industry agglomeration in Yangtze River Delta region of China from 2003 to 2014. The results show that the agglomeration level of textile industry in Yangtze River Delta region of China has experienced four stages: rapid growth, steady development, rapid decline and slow recovery. Through the analysis of the causes of the changes of agglomeration level namely EG index in each stage, this paper has found that the textile industry in Yangtze River Delta has several problems in industrial structure and enterprise development. Therefore, the corresponding recommendations were presented to promote the healthy development of the textile industry in Yangtze River Delta region.

  6. The agglomeration, coalescence and sliding of nanoparticles, leading to the rapid sintering of zirconia nanoceramics.

    Science.gov (United States)

    Kocjan, Andraž; Logar, Manca; Shen, Zhijian

    2017-05-31

    Conventional sintering is a time- and energy-consuming process used for the densification of consolidated particles facilitated by atomic diffusion at high temperatures. Nanoparticles, with their increased surface free energy, can promote sintering; however, size reduction also promotes agglomeration, so hampering particle packing and complete densification. Here we show how the ordered agglomeration of zirconia primary crystallites into secondary particle assemblies ensures their homogeneous packing, while also preserving the high surface energy to higher temperatures, increasing the sintering activity. When exposed to intense electromagnetic radiation, providing rapid heating, the assembled crystallites are subjected to further agglomeration, coalescence and sliding, leading to rapid densification in the absence of extensive diffusional processes, cancelling out the grain growth during the initial sintering stages and providing a zirconia nanoceramic in only 2 minutes at 1300 °C.

  7. Strength of wet agglomerates of spherical particles: effects of friction and size distribution

    Science.gov (United States)

    Vo, Thanh-Trung; Mutabaruka, Patrick; Delenne, Jean-Yves; Nezamabadi, Saeid; Radjai, Farhang

    2017-06-01

    We investigate the mechanical behavior of wet granular agglomerates composed of spherical particles by means of molecular dynamics simulations. The capillary cohesion force is modeled as an attraction force at the contact between two particles and expressed as an explicit function of the gap and volume of the liquid bridge. We are interested in the effect of the friction coefficient between primary particles. The agglomerates are subjected to diametrical compression tests. We find that the deformation is ductile involving particle rearrangements. However, a well-defined stress peak is observed and the peak stress is used as a measure of the compressive strength of the agglomerate. The strength increases with friction coefficient but levels off at friction coefficients above 0.4. Furthermore, the compressive strength is an increasing function of particle size span.

  8. Reasons and remedies for the agglomeration of multilayered graphene and carbon nanotubes in polymers

    Directory of Open Access Journals (Sweden)

    Rasheed Atif

    2016-08-01

    Full Text Available One of the main issues in the production of polymer nanocomposites is the dispersion state of filler as multilayered graphene (MLG and carbon nanotubes (CNTs tend to agglomerate due to van der Waals forces. The agglomeration can be avoided by using organic solvents, selecting suitable dispersion and production methods, and functionalizing the fillers. Another proposed method is the use of hybrid fillers as synergistic effects can cause an improvement in the dispersion state of the fillers. In this review article, various aspects of each process that can help avoid filler agglomeration and improve dispersion state are discussed in detail. This review article would be helpful for both current and prospective researchers in the field of MLG- and CNT-based polymer nanocomposites to achieve maximum enhancement in mechanical, thermal, and electrical properties of produced polymer nanocomposites.

  9. Strength of wet agglomerates of spherical particles: effects of friction and size distribution

    Directory of Open Access Journals (Sweden)

    Vo Thanh-Trung

    2017-01-01

    Full Text Available We investigate the mechanical behavior of wet granular agglomerates composed of spherical particles by means of molecular dynamics simulations. The capillary cohesion force is modeled as an attraction force at the contact between two particles and expressed as an explicit function of the gap and volume of the liquid bridge. We are interested in the effect of the friction coefficient between primary particles. The agglomerates are subjected to diametrical compression tests. We find that the deformation is ductile involving particle rearrangements. However, a well-defined stress peak is observed and the peak stress is used as a measure of the compressive strength of the agglomerate. The strength increases with friction coefficient but levels off at friction coefficients above 0.4. Furthermore, the compressive strength is an increasing function of particle size span.

  10. The capital agglomeration of the Republic of Korea as a fuzzy central place system

    Directory of Open Access Journals (Sweden)

    Em Pavel P.

    2016-12-01

    Full Text Available Explosive urbanization in the Republic of Korea from 1950 to 2010 marked by a growth in extensive urban agglomerations rendered unproductive the approach that was commonly used in the central place theory and which considered every element of the settlement system as a point in a homogeneous space. The paper suggests an alternative concept of fuzzy central place that makes possible the understanding of an internal heterogeneity in the distribution of central functions within the limits of urban agglomerations. This research was conducted using the example of the Capital agglomeration - the main element of the Republic of Korea’s urban settlement system. This “island” country, isolated by North Korea, has seen fantastic economic growth in the second half of the 20th century.

  11. Characterization of size, surface charge, and agglomeration state of nanoparticle dispersions for toxicological studies

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Jingkun [Washington University in St. Louis, Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental and Chemical Engineering (United States); Oberdoerster, Guenter [University of Rochester, Department of Environmental Medicine (United States); Biswas, Pratim, E-mail: pratim.biswas@wustl.ed [Washington University in St. Louis, Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental and Chemical Engineering (United States)

    2009-01-15

    Characterizing the state of nanoparticles (such as size, surface charge, and degree of agglomeration) in aqueous suspensions and understanding the parameters that affect this state are imperative for toxicity investigations. In this study, the role of important factors such as solution ionic strength, pH, and particle surface chemistry that control nanoparticle dispersion was examined. The size and zeta potential of four TiO{sub 2} and three quantum dot samples dispersed in different solutions (including one physiological medium) were characterized. For 15 nm TiO{sub 2} dispersions, the increase of ionic strength from 0.001 M to 0.1 M led to a 50-fold increase in the hydrodynamic diameter, and the variation of pH resulted in significant change of particle surface charge and the hydrodynamic size. It was shown that both adsorbing multiply charged ions (e.g., pyrophosphate ions) onto the TiO{sub 2} nanoparticle surface and coating quantum dot nanocrystals with polymers (e.g., polyethylene glycol) suppressed agglomeration and stabilized the dispersions. DLVO theory was used to qualitatively understand nanoparticle dispersion stability. A methodology using different ultrasonication techniques (bath and probe) was developed to distinguish agglomerates from aggregates (strong bonds), and to estimate the extent of particle agglomeration. Probe ultrasonication performed better than bath ultrasonication in dispersing TiO{sub 2} agglomerates when the stabilizing agent sodium pyrophosphate was used. Commercially available Degussa P25 and in-house synthesized TiO{sub 2} nanoparticles were used to demonstrate identification of aggregated and agglomerated samples.

  12. Molecular dynamics study of self-agglomeration of charged fullerenes in solvents.

    Science.gov (United States)

    Banerjee, Soumik

    2013-01-28

    The agglomeration of fullerenes in solvents is an important phenomenon that is relevant to controlled synthesis of fullerene-based nanowires as well as fullerene-based composites. The molecular aggregation in solvents depends on the atomistic interactions of fullerene with the solvent and is made complicated by the fact that fullerenes accrue negative surface charges when present in solvents such as water. In the present work, we simulated fullerenes of varying size and shape (C60, C180, C240, and C540) with and without surface charges in polar protic (water), polar aprotic (acetone), and nonpolar (toluene) solvents using molecular dynamics method. Our results demonstrate that uncharged fullerenes form agglomerates in polar solvents such as water and acetone and remain relatively dispersed in nonpolar toluene. The presence of surface charge significantly reduces agglomerate size in water and acetone. Additionally, the relative influence of surface charge on fullerene agglomeration depends on the size and geometry of the fullerene with larger fullerenes forming relatively smaller agglomerates. We evaluated the diffusion coefficients of solvent molecules within the solvation shell of fullerenes and observed that they are much lower than the bulk solvent and are strongly associated with the fullerenes as seen in the corresponding radial distribution functions. To correlate agglomerate size with the binding energy between fullerenes, we evaluated the potential of mean force between fullerenes in each solvent. Consistent with the solubility of fullerenes, binding energy between fullerenes is the greatest in water followed by acetone and toluene. The presence of charge decreases the binding energy of fullerenes in water and thus results in dispersed fullerenes.

  13. Agglomeration effects in the labour market: an empirical analysis for Italy

    Directory of Open Access Journals (Sweden)

    Marusca De Castris

    2013-05-01

    Full Text Available Extensive and persistent geographic variability of the unemployment rate within the same region has been attributed to various causes. Some theories identify the “thickness” of markets as the source of positive externalities affecting labour market by improving the ability to match the skills requested by firms with those offered by workers. A recent paper by Gan and Zhang (2006 empirically confirms this hypothesis for the US labour markets. Agglomeration can be defined as aggregation of people, basically measured by city size, or as aggregation of firms, measured by cluster size (employment or number of plants. However, the population location and the industrial location are by far more similar in United States than in Europe and in Italy. Our paper aims to evaluate the effects of agglomeration on the local unemployment rate. The new methodological contribution of the study is the identification of both urban and industrial cluster agglomeration effects, using a wide set of control variables. Adjusting the system for the effects of sectorial and size shocks, as well as those relating to geographic structure and policy interventions, the results of our analysis differ from that for the United States. The study stresses the presence of negative and significant urbanisation externalities. We obtain, instead, positive effects concerning the geographic agglomeration of firms, and their thickness, in a specific area. Furthermore, positive and significant effects can be found in local systems with features of a district. Finally, the model distinguishes the negative effects of urban agglomerations (in terms of population density from positive firm’s agglomerations (in terms of density of local units.

  14. Development of import subtituting technologies for increasing productivity of sintering machines and strength of agglomerates

    Directory of Open Access Journals (Sweden)

    В. Л. Трушко

    2016-11-01

    Full Text Available A problem of industrial fluxed agglomerates self-destruction in the process of cooling after sintering has been examined. It has been revealed that the main reason of strength degradation is polymorphism of dicalcium silicate Ca2SiO4 (or short designation С2S: β-Ca2SiO4 ® γ-Ca2SiO4. Ways for increasing the  agglomerate  strength by physical and crystal-chemical stabilization of the high temperature modification of C2S have been proposed and tested. Physical stabilization of C2S agglomerate is increased with its structure reinforcement due to thickening of walls between large pores that is achieved by increasing height of the sintered layer through improvement of its gas permeability. The task is addressed by substituting the previously used import sintering ore with the  polydisperse ore from the Yakovlevo field, which improves the charge  pelletizing by 3-4 times and helps to bring the  height of the sintered layer and the strength of the domestic agglomerate up to the international best practice standards, while eliminating a need to purchase import high-vacuum   exhausters. In practice crystal-chemical stabilization of C2S within iron-ore  agglomerate is ensured by adding an  opti- mal multicomponent additive in the form of the    waste product  generated in production  of alumina  from bauxites, i.e. the red mud, to the initial sinter charge. Thus mechanical strength of agglomerates and pellets is increased by 5-10 % and their hot strength improves by 20-40 %. The productivity of sintering machines and blast furnaces improves by 5-10 %. Specific coke consumption reduces by 2-2.5 %. In production of iron-ore pellets red mud is substituting the import  bentonite.

  15. Predictive Measurement of the Structure of Land Use in an Urban Agglomeration Space

    Directory of Open Access Journals (Sweden)

    Fei Liu

    2017-12-01

    Full Text Available The scientific measurement of land use in space is an essential task in urban agglomeration studies, and the fractal feature is one of the most powerful tools for describing the phenomenon of space. However, previous research on the fractal feature of land use has mostly been conducted in urban space, and examines the fractal feature of different land use types, respectively; thus, the measurement of the relationship between different land use types was not realized. Meanwhile, previous prediction methods used for spatial land use mostly relied on subjective abstraction of the evolution, theoretically, regardless of whether they were calibrated, so that complete coverage of all the mechanisms could not be guaranteed. Based on this, here, we treat the land use structure in urban agglomeration space as the research object, and attempt to establish a fractal measure method for the relationship between different land use types in the space of urban agglomeration. At the same time, we use the allometric relationship between “entirety” and “local” to establish an objective forecast model for the land use structure in urban agglomeration space based on gray prediction theory, to achieve a predictive measurement of the structure of land use in urban agglomeration space. Finally, this study applied the methods on the Beijing–Tianjin–Hebei urban agglomeration to analyze the evolution of the stability of the structure of land use and achieve predictive measurement of the structure of land use. The results of the case study show that the methods proposed in this study can obtain the measurement of the relationship between different land use types and the land use prediction that does not depend on the subjective exploration of the evolution law. Compared with the measurement methods that analyzed the fractal feature of different land types, respectively, and the prediction methods that rely on subjective choice, the methods presented in this

  16. Two-stage fluidized-bed/cyclonic agglomerating incinerator. Technology spotlight report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-08-01

    The two-stage fluidized-bed/cyclonic agglomerating incinerator combines and improves upon the fluidized-bed, agglomeration/ incineration-technology and the cyclonic-combustion technology developed at Institute of Gas Technolgy (IGT) over many years. The result is a unique and extremely flexible incinerator for solid, liquid, and gaseous wastes. The system can operate over a wide range of conditions and has a destruction and removal efficiency (DRE) greater than 99.99%. Solid inorganic contaminants are contained within aglassy matrix, rendering them benign and suitable for disposal in an ordinary landfill.

  17. The Morphology of Urban Agglomerations for Developing Countries: A Case Study with China

    CERN Document Server

    Gangopadhyay, Kausik

    2010-01-01

    In this article, the relationship between two well-accepted empirical propositions regarding the distribution of population in cities, namely, Gibrat's law and Zipf's law, are rigorously examined using the Chinese census data. Our findings are quite in contrast with the most of the previous studies performed exclusively for developed countries. This motivates us to build a general environment to explain the morphology of urban agglomerations both in developed and developing countries. A dynamic process of job creation generates a particular distribution for the urban agglomerations and introduction of Special Economic Zones (SEZ) in this abstract environment shows that the empirical observations are in good agreement with the proposed model.

  18. In-Situ Agglomeration and De-agglomeration by Milling of Nano-Engineered Lubricant Particulate Composites for Cold Spray Deposition

    Science.gov (United States)

    Neshastehriz, M.; Smid, I.; Segall, A. E.

    2014-10-01

    Nano-engineered self-lubricating particles comprised of hexagonal-boron-nitride powder (hBN) encapsulated in nickel have been developed for cold spray coating of aluminum components. The nickel encapsulant consists of several nano-sized layers, which are deposited on the hBN particles by electroless plating. In the cold spray deposition, the nickel becomes the matrix in which hBN acts as the lubricant. The coating demonstrated a very promising performance by reducing the coefficient of friction by almost 50% and increasing the wear resistance more than tenfold. The coatings also exhibited higher bond strength, which was directly related to the hardenability of the particles. During the encapsulation process, the hBN particles agglomerate and form large clusters. De-agglomeration has been studied through low- and high-energy ball milling to create more uniform and consistent particle sizes and to improve the cold spray deposition efficiency. The unmilled and milled particles were characterized with Scanning Electron Microscopy, Energy-Dispersive X-Ray Spectroscopy, BET, and hardness tests. It was found that in low-energy ball milling, the clusters were compacted to a noticeable extent. However, the high-energy ball milling resulted in breakup of agglomerations and destroyed the nickel encapsulant.

  19. Retour sur le drame de l’Île des Diamants : l’investissement immobilier des grands projets urbains à Phnom-Penh

    Directory of Open Access Journals (Sweden)

    Gabriel Fauveaud

    2011-05-01

    Full Text Available Cet article se propose de revenir sur la mort, suite à un mouvement de foule qui eut lieu le 22 novembre 2010, de plus de 350 personnes sur le pont d’un grand projet urbain privé actuellement en construction à Phnom-Penh. Il s’agira pour nous, à partir de ce drame marquant, de souligner certaines dynamiques contemporaines de la construction des espaces urbains de la capitale cambodgienne. A travers le grand projet de l’Île des Diamants, nous souhaitons interroger le rôle des grands promoteurs immobiliers dans la fabrication de la capitale. Pour ce faire, nous évoquerons l’internationalisation des modes de construction en Asie du Sud-Est et au Cambodge qui se caractérise par un retrait de la planification urbaine et une multiplication des projets urbains privés. L’exemple de l’Île des Diamants nous permettra d’illustrer certaines grandes tendances de l’urbanisation à Phnom-Penh. Nous montrerons comment l’évolution du discours sur la ville moderne génère des antagonismes au sein de la politique urbaine actuelle, et interrogerons la capacité des grands investisseurs immobiliers à fabriquer des espaces urbains pérennes.Through this article, we would like to underline few main dynamics of the contemporary urban development of Phnom‑Penh after more than 350 people died on Diamonds Island, a new private large scale project under construction. The Diamonds Island project questions the role of the large scale real-estate investors in the fabrication of the urban space. We will get onto the evolution of the internationalization of the production of the urban space. By this end, we will be able to replace the “urban project” within the institutional and historical local reality. Through the particular example of the Diamonds Island, we will approach the evolution of the urban modernity understood as a marketing strategy. Finally, the Diamond Island tragedy reveals the antagonisms of the current urban politic and

  20. Le rôle des associations de résidants dans la gestion des services urbains à Hyderabad

    Directory of Open Access Journals (Sweden)

    Marie-Hélène Zérah

    2011-11-01

    Full Text Available Centré sur les associations de résidants des quartiers résidentiels de la ville d’Hyderabad, cet article cherche à comprendre comment ces associations concourent à la redéfinition des modalités de l’action publique. Une première partie détaille la politique municipale de délégation de responsabilités à ces associations, en matière de services urbains, et les efforts de la part des habitants pour affirmer une identité de quartier et organiser la défense de leurs intérêts. Ces deux logiques  « top down » de la municipalité et « civiles ou bottom up » se renforcent mutuellement et, pour la municipalité comme pour les  associations, l’échelle de la localité apparaît comme une échelle pertinente de résolution de certains problèmes urbains. Une deuxième partie s’intéresse à la manière dont les associations de quartiers mettent en place des stratégies pour sortir de l’enfermement local en renforçant leurs compétences, en démocratisant leur fonctionnement et en créant des fédérations qui s’inscrivent dans des réseaux nationaux. Enfin, les conséquences en matière de gouvernance urbaine du rôle croissant de ces associations dans les affaires urbaines sont analysées dans une troisième partie. Celle-ci montre que les partenariats privilégiés entre la municipalité et les associations de résidants s’accompagnent d’une capture des ressources municipales. Cette forme de gouvernance par contrat se concrétise par une spatialisation de l’action publique qui fortifie l’ancrage des associations et renforce leur rôle de contre-pouvoir face aux institutions politiques locales.  Focused on residents' associations in the residential areas of Hyderabad, this article seeks to understand how these associations contribute to a shift in the conduct of public policy. The first part details the municipality’s policies of urban services delegated management to these associations and the efforts by

  1. Transfert sol-plantes des métaux lourds des boues d'épuration urbaines et industrielles

    OpenAIRE

    Lassoued, Nadjla; Bilal, Essaïd; Rejeb, Saloua; Gallice, Frédéric; Doumas, Marc

    2012-01-01

    National audience; Le principal objectif de cette étude consiste à évaluer sur le blé et le colza l'effet de deux types de boues résiduaires (boues urbaines / boues industrielles) chargées en métaux lourds surtout en plomb et chrome. Ces boues sont apportées à différentes doses (5,25, 50 et 100 t/ha). Nous nous intéressons donc à la croissance et l'absorption des métaux lourds par les plantes (le blé dur et le colza) et à suivre le devenir de ces derniers dans le sol afin de prévenir des phén...

  2. Lutte contre la pauvreté et l’exclusion urbaine à travers l’exemple de la Tunisie

    OpenAIRE

    Bounouh, Abdelala

    2013-01-01

    La Tunisie peut être considérée parmi les premiers pays qui se sont intéressés à la question de la pauvreté et de l’exclusion urbaine. La fixation de seuils de pauvreté et des programmes de lutte contre la précarité remonte déjà à la fin des années 60. Cependant il est établi que l’approche en matière de pauvreté a connu un intérêt particulier avec l’application du Programme d’ajustement structurel (PAS), qui s’est traduit par une décompression des dépenses sociales et par une précarité plus ...

  3. Eric Charmes, La ville émiettée. Essai sur la clubbisation de la vie urbaine

    Directory of Open Access Journals (Sweden)

    Raphaël Frétigny

    2011-11-01

    Full Text Available Si son titre ne le traduit pas explicitement, le récent ouvrage d’Eric Charmes La ville émiettée. Essai sur la clubbisation de la vie urbaine porte essentiellement sur l’espace périurbain, dont l’auteur est aujourd’hui un des meilleurs spécialistes en France. Ce travail se situe à l’opposé des stigmatisations habituelles du périurbain, trop souvent présenté comme un junk space peuplé de populations rejetées hors des villes. Au contraire, l’auteur met ce « tiers espace » (Vanier, 2001 au cœur...

  4. Mobilité urbaine : de l'automobilisme à l'éco-mobilité. Un long chemin…

    OpenAIRE

    HUGUENIN-RICHARD, Florence

    2010-01-01

    National audience; On parle beaucoup de mobilité urbaine, en témoignent les nombreux ouvrages publiés depuis le début des années 1990, date à laquelle remonte la prise de conscience du défi environnemental lié à la pollution atmosphérique anthropique. Il faut dire que c'est une question de société qui appelle certaines interrogations : comment diminuer le trafic automobile sans réduire la mobilité ? Est-il possible de faire marche-arrière en contenant l'urbanisation ? Peut-on vivre sans voitu...

  5. Marketing urbain et projet de ville : parole et représentations géographiques des acteurs

    OpenAIRE

    Rosemberg-Lasorne, Muriel

    1997-01-01

    Sans qu’il soit possible à première vue de percevoir l’intérêt pour les villes de se promouvoir par le recours au discours publicitaire, deux observations justifient d’engager une recherche géographique sur ce que l’on désigne sous le nom de marketing urbain. D’une part dans quelques villes l’action promotionnelle apparaît durable, systématique, ce qui invite à ne pas la réduire à un phénomène de mode, sans signification. D’autre part la coïncidence de l’action promotionnelle et d’actions de ...

  6. Un centre d'agriculture urbaine à Lausanne. Au croisement entre un couloir écologique et un plateau industriel

    OpenAIRE

    Bersier, Marine

    2017-01-01

    L'alimentation vit une révolution comportementale importante. La population devient plus sensible à ce qu'elle mange et exprime des attentes en terme de traçabilité des ingrédients en privilégiant les produits frais distribués à travers des circuits courts. Parallèlement, les interventions visant à l'intégration de l'agriculture dans l'environnement urbain se multiplient et viennent compléter le réseau vert de la ville. Le centre d'agriculture offre un lieu d'échange entre les différents acte...

  7. Réflexion sur la gouvernance urbaine à Alger. Prérogatives institutionnelles et monopoles politiques

    OpenAIRE

    Icheboudène, Larbi

    2015-01-01

    Cette réflexion se propose de traiter la question de la gouvernance. Après un bref rappel de l’état des lieux du champ théorique des approches, la question de la gouvernance est envisagée sur la base de l’expérience de la ville d’Alger. Les termes de la problématique de la gouvernance sont d’une part, les enjeux sociopolitiques qui président au devenir d’une société urbaine et de sa capitale, d’autre part, ceux relatifs aux statuts parfois précaires de la capitale et des instances de sa gesti...

  8. Renouvellement urbain et revalorisation des espaces publics dans un City Improvement District du centre ville de Johannesburg

    Directory of Open Access Journals (Sweden)

    Elisabeth Peyroux

    2010-09-01

    Full Text Available Illustration 1 - Gandhi Square Auteur : Juliana Irene Smith, spectacle « Super Green Apple Girl », octobre 2006.Gandhi Square (ex-Van der Bijl Square illustre les stratégies de renouvellement urbain mises en place à Johannesburg dans le cadre de Partenariats Public-Privé. Ancien symbole de la ségrégation du système de transport sous l’apartheid, ce terminal de bus du Central Business District, affecté par le déclin économique et la dégradation du centre-ville pendant les années 1990, fait au...

  9. Short term effect of urban air pollution on respiratory disease, especially chronic obstructive pulmonary disease (COPD). Analysis of studies published from 1962 to january 2000; Impact a court terme de la pollution atmospherique urbaine sur l'insuffisance respiratoire par bronchopneumopathie chronique obstructive (BPCO). Synthese des etudes, publiees de 1962 a janvier 2000

    Energy Technology Data Exchange (ETDEWEB)

    Desqueyroux, H.; Momas, I. [Universite Rene Descartes, Faculte des Sciences Pharmaceutiques et Biologiques, Lab. d' Hygiene et de Sante Publique, 75 - Paris (France)

    2001-02-01

    This review presents a synthesis of studies published from 1962 to 2000 on the relations between air pollution and chronic obstructive pulmonary disease (COPD): 12 ecological epidemiological studies, 6 epidemiological panel studies, and 11 controlled human exposure trials. The controlled trials, ecological time-based epidemiological studies and panels are examined successively followed by a discussion of their methodology and results. The controlled trials either do no highlight effects or show effects having no clinical significance since variations are similar to physiological variability. For epidemiological studies reporting individual data, the results point to a particle effect (two studies). This effect of particles is found in ecological studies which also describe an impact of ozone, sometimes of sulfur dioxide and less often of nitrogen dioxide. In conclusion, patients suffering from COPD are generally regarded as a group sensitive to air pollution, as suggested by the results of numerous ecological epidemiological studies. Rare individual studies provide a few arguments supporting this assumption. (authors)

  10. Programme of air surveillance and health 9 towns. Synthesis review. Surveillance of effects on the health in relation with air pollution in urban area. Phase 2; Programme de surveillance Air et Sante 9 villes. Revue de synthese. Surveillance des effets sur la sante lies a la pollution atmospherique en milieu urbain. Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-06-15

    The InVS published its first results on the Nine-City Air and Health Surveillance Programme (PSAS-9) in March 1999. This phase I pointed out that it was possible for various specialists in the field of air pollution and health to gather around a common set of problems. They also found a link between the daily variations of all the urban air pollution indicators and the total, cardio-vascular and respiratory mortality which, based on French data, contributed to strengthen scientific knowledge in this field. Today's report presents the results of phase Il of the PSAS-9 programme which essentially aimed at assessing the short-term exposure-risk relationships between pollution indicators and hospital admission indicators. This second phase also allowed to confirm the results of phase I on the short-term effect of air pollution on mortality thanks to longer periods of study. Exploratory analysis using new indicators and sensitivity analysis on the pertinence of results were also conducted. Finally, methodological tools were developed in order to optimise data collection and statistical modelization. All these results enabled the quantification of the short-term health impact of air pollution on the PSAS-9 cities. PSAS-9 is now an ongoing epidemiological surveillance programme on the effects of urban air pollution on health, providing information tools to decision-makers and the general population. (author)

  11. Situation of regional plans for air quality. Acknowledgement of sanitary aspects. Situation of realised impact studies of urban air pollution; Bilan des plans regionaux pour la qualite de l'air. Prise en compte des aspects sanitaires. Bilan des etudes d'impact de la pollution atmospherique urbaine realisees

    Energy Technology Data Exchange (ETDEWEB)

    D' Helf, M.; Cassadou, S

    2005-07-01

    The law on air and use of energy recommended in 1996 the implementation of regional plans for air quality (P.Q.R.A.) that have to rely on an evaluation of air pollution effects on health. 21 P.Q.R.A. have been published and the report gives the situation, their sanitary orientations and their applications. An inquiry lead in the 21 regions, near the different regional actors in the air and health field completes the report. (N.C.)

  12. Programme of air surveillance Air and Health 9 towns. Surveillance of effects on health in relation with air pollution in urban area. Phase 2; Programme de surveillance Air et Sante 9 villes. Surveillance des effets sur la sante lies a la pollution atmospherique en milieu urbain. Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-06-15

    The InVS published its first results on the Nine-City Air and Health Surveillance Programme (PSAS-9) in March 1999. This phase I pointed out that it was possible for various specialists in the field of air pollution and health to gather around a common set of problems. They also found a link between the daily variations of all the urban air pollution indicators and the total, cardio-vascular and respiratory mortality which, based on French data, contributed to strengthen scientific knowledge in this field. Today's report presents the results of phase Il of the PSAS-9 programme which essentially aimed at assessing the short-term exposure-risk relationships between pollution indicators and hospital admission indicators. This second phase also allowed to confirm the results of phase I on the short-term effect of air pollution on mortality thanks to longer periods of study. Exploratory analysis using new indicators and sensitivity analysis on the pertinence of results were also conducted. Finally, methodological tools were developed in order to optimise data collection and statistical modelization. All these results enabled the quantification of the short-term health impact of air pollution on the PSAS-9 cities. PSAS-9 is now an ongoing epidemiological surveillance programme on the effects of urban air pollution on health, providing information tools to decision-makers and the general population. (author)

  13. Considering the sanitary aspects in regional plans for air quality. Situation of sanitary impacts of urban air pollution studies; Prise en compte des aspects sanitaires dans les Plans regionaux pour la qualite de l'air. Bilan des etudes d'impact sanitaires de la pollution atmospherique urbaine realisees

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-12-15

    The law on air and the rational use of energy of the 30. september 1996 forecasts the setting up of regional planning for the air quality that have to rely on the support of an evaluation of sanitary effects of air pollution. To help the local sanitary authorities in this mission, the National Institute of Sanitary Surveillance and the C.I.R.E. have realised a methodological guide on evaluation of sanitary impact of urban air pollution in different contexts. (N.C.)

  14. Atmospheric pollution and heating plants in urban area. What technical solutions for the coal and the heavy oil? For which costs?; Pollution atmospherique et chaufferies en milieu urbain. Quelles solutions techniques pour le charbon et le fioul lourd?. A quel couts?

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    In France, furnaces fed with coal and heavy fuel and established in urban area, are bound by many restraints: a reinforcement of the regulations on atmospheric emissions, a strong social demand bound to the urban air quality improvement and a necessary costs mastership. So buildings managers and persons responsible for district heating are confronted with technical and strategical choices. To answer their questions ADEME organized a day of information around four main themes: the urban heating in France, actions on fuels, possible technics for the smokes desulfurization and nitrogen oxides reduction, costs and financing of the solutions. (A.L.B.)

  15. Les lieux de l´interculturalité : une image de la complexité urbaine

    Directory of Open Access Journals (Sweden)

    Marina Marengo

    1999-04-01

    Full Text Available La recherche en question s´attache à étudier les lieux d´échange et de transaction entre population autochtone et immigrants - mais aussi entre les différents groupes d´immigrés au sein de l´agglomération lausannoise- ainsi que le contexte de leur émergence, leur histoire et les discours qui les supportent. Cette démarche permet de rendre compte de ces mêmes lieux, de leur rôle dans la ville et des différents types de relations qui peuvent s´y nouer, en privilégiant les représentations, la construction du sens, la manière de structurer l´espace. L´intérêt pour ces "lieux hybrides" est né, en réalité, de l´idée que l´immigration dans les centres urbains favorise de plus en plus des "cultures de la mixité" qui représentent un enjeu central en matière de cohabitation et d´intégration des populations à l´échelle urbaine. L´étude est centrée sur la tentative de saisir la signification de ces lieux hybrides dans la perspective propre aux acteurs qui les fréquentent ou les jugent. On aura ainsi recours aux méthodes de l´observation participante, à l´enregistrement de situations d´interaction et à leur interprétation ainsi qu´à des entretiens non structurés dans le but de cerner dans le détail la mécanique des processus d´intégration et de ségrégation.

  16. Urban agglomerations and transformations of medium-sized towns in Poland

    Directory of Open Access Journals (Sweden)

    Runge Anna

    2016-09-01

    Full Text Available This analysis investigates medium-sized towns in Poland, i.e. those with a population between 20–100 thousand, located up to 100 km away from the main city of the agglomeration. The aim of this article is to compare the level of socio-economic development of Polish towns depending on their location in relation to the main city in the largest agglomerations in 1998 and 2013. Three zones of distance from the main city of each agglomeration have been taken into consideration: a. the inner zone, reaching up to 25 km from the main city; b. the outer zone located at a distance of 25 to 50 km from the main city, and c. the peripheral zone, located at a distance of 50 to 100 km from the main city and including the medium-size towns located outside the agglomeration system. This analysis of the distribution of medium-sized towns and their level of socio-economic development has shown various levels of changes which depend on the distance from the main city of the agglomeration. In 1998, the highest level of development of the medium-sized towns was recorded in towns outside of these agglomeration systems, i.e. those located most remotely from the main city (peripheral zone. Most of the medium-sized towns are situated at a distance of 50–100 km from Warszawa, Kraków, Łódź, Lublin, Gdańsk and have developed their own local, or even regional labour markets and some of them have even provided administrative functions in the past as voivodeship capitals. Only in the Poznań agglomeration, the level of development of medium-sized towns was higher in the immediate surroundings of the main city (25 km. The medium-sized towns in all zones of the distance from the main city in the Wrocław agglomeration represented a similar level of development. By 2013, the level of development of the medium-sized towns in the peripheral zone in all investigated settlement systems had decreased, with a significant improvement in the level of development of the towns in

  17. An improved model for estimating fractal structure of silica nano-agglomerates in a vibro-fluidized bed

    Directory of Open Access Journals (Sweden)

    A Esmailpour

    2016-10-01

    Full Text Available A study has been conducted to determine the effects of operating conditions such as vibration frequency, vibration amplitude on the fractal structure of silica (SiO2 nanoparticle agglomerate in a vibro-fluidized bed. An improved model was proposed by assimilation of fractal theory, Richardson-Zaki equation and mass balance. This model has been developed to predict the properties of nanoparticle agglomerate, such as fractal dimension and its size. It has been found out the vibration intensity increase leads to a slight reduction in fractal dimension of agglomerate. This Paper is also indicated that the size of agglomerate has the same behavior as fractal dimension with respect to vibration intensity changes. This study demonstrated that the fractal dimension of Silica nanoparticle agglomerate is in the range of 2.61 to 2.69 and the number of primary particles in the agglomerate is in the order of 1010. The vibration frequency is more impressive than its amplitude on agglomerate size reduction. Calculated Minimum fluidization velocity by applying predicted agglomerate sizes and experimental data are acceptable fitted.

  18. Des risques « naturels » aux politiques urbaines à Mexico

    Directory of Open Access Journals (Sweden)

    François Mancebo

    2009-07-01

    Full Text Available L’agglomération de Mexico, à plus de 2 000 mètres d’altitude, adossée à la Sierra Madre et la Cordillère Volcanique est assise sur un site accueillant mais redoutable. Il s’agit d’un des endroits les plus exposés du globe, soumis à une combinaison de risques naturels, de risques technologiques souvent mal maîtrisés dus à des industries lourdes, de nuisances, de cumul des polluants et d’un épuisement des ressources locales utilisables, tout particulièrement les ressources en eau. Après le séisme dévastateur de 1985, les acteurs de l’aménagement de Mexico tentent d’intégrer risques et durabilité dans la définition de nouvelles politiques urbaines. Mais, si les risques sont bien identifiés et des réponses sont données, leur applicabilité est quasi-nulle. Une approche normative et n’incluant pas l’ensemble de l’agglomération, mais utilisant les périphéries pour améliorer la durabilité des centres (sorte de durabilité importée à l’échelle de la métropole explique cette situation. Comme dans le mythe de Sisyphe, acteurs locaux et nationaux tentent de faire remonter la pente au rocher du risque mais ce dernier finit toujours par redescendre ? C’est qu’en réalité le problème n’est pas le rocher. Le problème, c’est la pente, c’est-à-dire le substrat fait de représentations territoriales et d’usages de l’espace qui fondent la société mexicaine, sur laquelle roule le rocher.Mexico City is located at an altitude of over 2 000 metres where it occupies an attractive but hazardous site hemmed in by the Sierra Madre and volcanic mountain ranges.The site is one of the most disaster-prone locations in the world, threatened by a combination of natural hazards, poorly controlled technological hazards created by the city’s heavy industry, pollution – particularly air pollution and diminishing local resources, the most seriously threatened being water. Since the devastating earthquake

  19. Peut-on cartographier des taches urbaines à partir d’images Google Earth ?

    Directory of Open Access Journals (Sweden)

    Johanna Baro

    2014-07-01

    Full Text Available L’étude présentée ici expose les résultats d’un traitement d’images Google Earth dont le but est la cartographie des agglomérations d’Afrique de l’Ouest de plus de 500 000 habitants. Les images accessibles ne disposant pas d’informations spectrales précises (s’agissant de simples images couleur RVB, la méthodologie développée pour l’identification des agglomérations se base sur l’exploitation d’images en teintes de gris pour en extraire les caractéristiques texturales des zones densément bâties. Certaines images couvrant les agglomérations étudiées résultent de la composition en mosaïque d’images satellites acquises dans des conditions différentes. Avant toute exploitation des images, un prétraitement d’égalisation est nécessaire afin d’obtenir une vue uniforme à partir de la mosaïque. Plus précisément, il s’agit d’annuler les différences entre les luminances sur chaque morceau de mosaïque. Nous présentons ici une méthode d’égalisation inspirée de l’algorithme « Midway ». Cet algorithme a originellement été proposé pour uniformiser les luminances sur des paires d’images stéréo. Dans le cas présent, la difficulté consiste à adapter cette technique dans le cas d’images ne présentant pas strictement la même information. Le principe d’égalisation va consister à repérer et à apparier les histogrammes de zones semblables sur les sous-images composant la mosaïque. L’extraction des taches urbaines à partir des images prétraitées est ensuite réalisée par la mise en œuvre de séquences d’opérateurs de la Morphologie Mathématique. Les résultats obtenus ont été validés par une comparaison avec les agglomérations qui ont été cartographiées par photo-interprétation à partir d’images Google Earth et présentées dans la base de données Africapolis.

  20. Biomass-Ash-Induced Agglomeration in a Fluidized Bed. Part 1: Experimental Study on the Effects of a Gas Atmosphere

    DEFF Research Database (Denmark)

    Ma, Teng; Fan, Chuigang; Hao, Lifang

    2016-01-01

    with quartz sand and fluidized by the gas mixtures of N2/CO2, N2/H2, and N2/steam or by air. At 550 °C, the bed temperature is increased at the rate of 3 °C/min until defluidization occurs. In this way, the defluidization temperature can be determined, which represents the agglomeration tendency....... Understanding of the agglomeration in various atmospheres is crucial to optimize the design and operation conditions. This study focuses on the effects of gases on agglomeration tendency with different types of biomass, including corn straw, rice straw, and wheat straw. The biomass ash samples are mixed....... The agglomerates are analyzed by scanning electron microscopy–energy-dispersive X-ray spectrometry (SEM–EDS) for morphology and elemental composition. Significant differences are observed on the defluidization temperature (Td) and agglomeration mechanisms in different gas atmospheres. Td in H2 and steam...

  1. Are carbon nanotube effects on green algae caused by shading and agglomeration?

    Science.gov (United States)

    Schwab, Fabienne; Bucheli, Thomas D; Lukhele, Lungile P; Magrez, Arnaud; Nowack, Bernd; Sigg, Laura; Knauer, Katja

    2011-07-15

    Due to growing production, carbon nanotubes (CNT) may soon be found in a broad range of products and thus in the environment. In this work, an algal growth test was developed to determine effects of pristine and oxidized CNT on the green algae Chlorella vulgaris and Pseudokirchneriella subcapitata. CNT suspensions were prepared in algal test medium and characterized taking into account the suspension age, the reduced light transmittance of nanoparticle suspensions defined as shading of CNT and quantified by UV/vis spectroscopy, and the agglomeration of the CNT and of the algal cells. Growth inhibition and photosynthetic activity were investigated as end points. Growth of C. vulgaris was inhibited with effect concentrations of 50% (EC(50)) values of 1.8 mg CNT/L and of 24 mg CNT/L in well dispersed and in agglomerated suspensions, respectively, and 20 mg CNT/L and 36 mg CNT/L for P. subcapitata, respectively. However, the photosynthetic activity was not affected. Growth inhibition was highly correlated with the shading of CNT and the agglomeration of algal cells. This suggests that the reduced algal growth might be caused mainly by indirect effects, i.e. by reduced availability of light and different growth conditions caused by the locally elevated algal concentration inside of CNT agglomerates.

  2. Biomass ash-bed material interactions leading to agglomeration in FBC

    DEFF Research Database (Denmark)

    Visser, H.J.M.; van Lith, Simone Cornelia; Kiel, J.H.A.

    2008-01-01

    In (bubbling) fluidized-bed combustion and gasification of biomass, several potential problems are associated with the inorganic components of the fuel. A major problem area is defluidization due to bed agglomeration. The most common found process leading to defluidization in commercial-scale ins......In (bubbling) fluidized-bed combustion and gasification of biomass, several potential problems are associated with the inorganic components of the fuel. A major problem area is defluidization due to bed agglomeration. The most common found process leading to defluidization in commercial......-scale installations is "coating-induced" agglomeration. During reactor operation, a coating is formed on the surface of bed material grains and at certain critical conditions (e.g., coating thickness or temperature) sintering of the coatings initiates the agglomeration. In an experimental approach, this work...... describes a fundamental study on the mechanisms of defluidization. For the studied process of bed defluidization due to sintering of grain-coating layers, it was found that the onset of the process depends on (a) a critical coating thickness, (b) on the fluidization velocity when it is below approximately...

  3. Agglomeration and firm performance: One firm’s medicine is another firm’s poison

    NARCIS (Netherlands)

    Knoben, J.; Arikan, A.; Oort, F.G. van; Raspe, O.

    2016-01-01

    In this paper, we aim to reduce the ambiguity surrounding the agglomeration–performance relationship. We do so by taking firm-level and agglomeration-level heterogeneity into account simultaneously and focusing on the interactions between these two levels of analysis in explaining the effect of

  4. Cities in transition: monitoring growth trends in Delhi urban agglomeration 1991-2001

    Directory of Open Access Journals (Sweden)

    Debnath Mookherjee

    2004-12-01

    Full Text Available An analysis based on census data for the decade 1991-2001 indicates change in the urban structure of the Delhi Urban Agglomeration, India. The number and rate of growth of cen-sus towns and the urban core are examined. The pattern shows emerging traits of urban spread and provides an investigative framework for future research.

  5. A complex network approach for nanoparticle agglomeration analysis in nanoscale images

    Science.gov (United States)

    Machado, Bruno Brandoli; Scabini, Leonardo Felipe; Margarido Orue, Jonatan Patrick; de Arruda, Mauro Santos; Goncalves, Diogo Nunes; Goncalves, Wesley Nunes; Moreira, Raphaell; Rodrigues-Jr, Jose F.

    2017-02-01

    Complex networks have been widely used in science and technology because of their ability to represent several systems. One of these systems is found in Biochemistry, in which the synthesis of new nanoparticles is a hot topic. However, the interpretation of experimental results in the search of new nanoparticles poses several challenges. This is due to the characteristics of nanoparticle images and due to their multiple intricate properties; one property of recurrent interest is the agglomeration of particles. Addressing this issue, this paper introduces an approach that uses complex networks to detect and describe nanoparticle agglomerates so to foster easier and more insightful analyses. In this approach, each detected particle in an image corresponds to a vertice and the distances between the particles define a criterion for creating edges. Edges are created if the distance is smaller than a radius of interest. Once this network is set, we calculate several discrete measures able to reveal the most outstanding agglomerates in a nanoparticle image. Experimental results using images of scanning tunneling microscopy (STM) of gold nanoparticles demonstrated the effectiveness of the proposed approach over several samples, as reflected by the separability between particles in three usual settings. The results also demonstrated efficacy for both convex and non-convex agglomerates.

  6. Agglomeration of Celecoxib by Quasi Emulsion Solvent Diffusion Method: Effect of Stabilizer.

    Science.gov (United States)

    Maghsoodi, Maryam; Nokhodchi, Ali

    2016-12-01

    Purpose: The quasi-emulsion solvent diffusion (QESD) has evolved into an effective technique to manufacture agglomerates of API crystals. Although, the proposed technique showed benefits, such as cost effectiveness, that is considerably sensitive to the choice of a stabilizer, which agonizes from a absence of systemic understanding in this field. In the present study, the combination of different solvents and stabilizers were compared to investigate any connections between the solvents and stabilizers. Methods: Agglomerates of celecoxib were prepared by QESD method using four different stabilizers (Tween 80, HPMC, PVP and SLS) and three different solvents (methyl acetate, ethyl acetate and isopropyl acetate). The solid state of obtained particles was investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy. The agglomerated were also evaluated in term of production yield, distribution of particles and dissolution behavior. Results: The results showed that the effectiveness of stabilizer in terms of particle size and particle size distribution is specific to each solvent candidate. A stabilizer with a lower HLB value is preferred which actually increased its effectiveness with the solvent candidates with higher lipophilicity. HPMC appeared to be the most versatile stabilizer because it showed a better stabilizing effect compared to other stabilizers in all solvents used. Conclusion: This study demonstrated that the efficiency of stabilizers in forming the celecoxib agglomerates by QESD was influenced by the HLB of the stabilizer and lipophilicity of the solvents.

  7. Direct numerical simulations of agglomeration of circular colloidal particles in two-dimensional shear flow

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young Joon, E-mail: yjchoi@uvic.ca; Djilali, Ned, E-mail: ndjilali@uvic.ca [Institute for Integrated Energy Systems and Department of Mechanical Engineering, University of Victoria, Victoria, British Columbia V8W 3P6 (Canada)

    2016-01-15

    Colloidal agglomeration of nanoparticles in shear flow is investigated by solving the fluid-particle and particle-particle interactions in a 2D system. We use an extended finite element method in which the dynamics of the particles is solved in a fully coupled manner with the flow, allowing an accurate description of the fluid-particle interfaces without the need of boundary-fitted meshes or of empirical correlations to account for the hydrodynamic interactions between the particles. Adaptive local mesh refinement using a grid deformation method is incorporated with the fluid-structure interaction algorithm, and the particle-particle interaction at the microscopic level is modeled using the Lennard-Jones potential. Motivated by the process used in fabricating fuel cell catalysts from a colloidal ink, the model is applied to investigate agglomeration of colloidal particles under external shear flow in a sliding bi-periodic Lees-Edwards frame with varying shear rates and particle fraction ratios. Both external shear and particle fraction are found to have a crucial impact on the structure formation of colloidal particles in a suspension. Segregation intensity and graph theory are used to analyze the underlying agglomeration patterns and structures, and three agglomeration regimes are identified.

  8. Evidence of zirconium nano-agglomeration in as-cast dilute U–Zr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, S. [Radiochemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India); Kaity, S. [Radiometallurgy Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India); Saify, M.T.; Jha, S.K. [Atomic Fuel Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India); Pujari, P.K., E-mail: pujari@barc.gov.in [Radiochemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India)

    2014-09-15

    Microstructure evaluation of as-cast and annealed U–Zr (Zr = 2, 6 and 10 wt.%) alloys has been carried out for the first time using positrons as a probe. The chemical signature in the matter–antimatter annihilation gamma and the positron lifetime data suggests that majority of positrons are annihilating from Zr sites in the as-cast alloys. The results have been interpreted as due to the presence of Zr nano-agglomerates in the as-cast alloys which have a higher positron affinity as compared to the rest of the U matrix. A minimum agglomerate size of ∼2 nm diameter has been calculated from the difference in positron affinity between the agglomerates and the matrix. Upon annealing, the Zr signature in the annihilation gamma photons vanishes suggesting that the Zr agglomerates diffuse out of U matrix and form micron-sized precipitates. This has been confirmed by scanning electron microscopy which shows a 3 times increase in the surface density of the precipitates in the annealed alloys as compared to the as-cast ones. Shorter positron diffusion length (measured using slow positron beam) as compared to precipitate separation has been invoked to explain the observed data.

  9. Do Universities Generate Agglomeration Spillovers? Evidence from Endowment Value Shocks. NBER Working Paper No. 15299

    Science.gov (United States)

    Kantor, Shawn; Whalley, Alexander

    2009-01-01

    In this paper we quantify the extent and magnitude of agglomeration spillovers from a formal institution whose sole mission is the creation and dissemination of knowledge--the research university. We use the fact that universities follow a fixed endowment spending policy based on the market value of their endowments to identify the causal effect…

  10. Modelling Inter-Particle Forces and Resulting Agglomerate Sizes in Cement-Based Materials

    DEFF Research Database (Denmark)

    Kjeldsen, Ane Mette; Geiker, Mette Rica

    2005-01-01

    The theory of inter-particle forces versus external shear in cement-based materials is reviewed. On this basis, calculations on maximum agglomerate size present after the combined action of superplasticizers and shear are carried out. Qualitative experimental results indicate that external shear...

  11. Agglomeration of particles during coal combustion in multistage spouted fluidized tower

    Energy Technology Data Exchange (ETDEWEB)

    Liu, J.X.; Gao, J.H.; Gao, J.M.; Wang, X.F.; Wu, S.H. [Harbin Institute of Technology, Harbin (China)

    2009-05-15

    An experimental platform of spray agglomeration has been designed and built for removing small fly ash particles (PM10) from coal combustion. Systematic experiments were conducted in a multistage spouted tower using kinds of agglomerant solutions. The particle concentration increases greatly from the first stage to the second stage of the tower. With the increase of flue gas flow rate the oscillation of impulse signal response curves increases and the internal circulation of the tower intensifies. The influencing factors such as the surfactant, pH value, flow rate of the agglomerant solutions and inlet flue gas temperature were analyzed. SEM was used to analyze the microstructure of the particles. Final results indicate that the special shape of a multistage spouted fluidized tower has significant influences on the effect of agglomeration. The findings from this work will be helpful to form the basis, and provide guidance for, further studies on the control of fine particles such as PM2.5 or even smaller.

  12. An Agglomeration Law for Sorting Networks and its Application in Functional Programming

    Directory of Open Access Journals (Sweden)

    Lukas Immanuel Schiller

    2017-01-01

    Full Text Available In this paper we will present a general agglomeration law for sorting networks. Agglomeration is a common technique when designing parallel programmes to control the granularity of the computation thereby finding a better fit between the algorithm and the machine on which the algorithm runs. Usually this is done by grouping smaller tasks and computing them en bloc within one parallel process. In the case of sorting networks this could be done by computing bigger parts of the network with one process. The agglomeration law in this paper pursues a different strategy: The input data is grouped and the algorithm is generalized to work on the agglomerated input while the original structure of the algorithm remains. This will result in a new access opportunity to sorting networks well-suited for efficient parallelization on modern multicore computers, computer networks or GPGPU programming. Additionally this enables us to use sorting networks as (parallel or distributed merging stages for arbitrary sorting algorithms, thereby creating new hybrid sorting algorithms with ease. The expressiveness of functional programming languages helps us to apply this law to systematically constructed sorting networks, leading to efficient and easily adaptable sorting algorithms. An application example is given, using the Eden programming language to show the effectiveness of the law. The implementation is compared with different parallel sorting algorithms by runtime behaviour.

  13. Definition of settlement agglomerations in Slovenia according to water management aspects

    Directory of Open Access Journals (Sweden)

    Leon Gosar

    2004-01-01

    Full Text Available Enforcement of the European Union’s legal order is bringing substantial expert involvement even in water management. The main act, the Water Framework Directive (WFD, is followed by numerous others. Substantial investments will be demanded even in Slovenia to comply with the Uniform Waste Water Treatment Directive (UWWTD and Integrated Pollution Prevention and Control Directive (IPPCD. On the operative utilities are dealt with by municipalities, while states have to fulfil national responsibilities to the EU. Timely achievement of goals demands coordinated activities based on expert guidelines. One of UWWTD’s basic parameters is the agglomeration, which is a uniform area of such compact settlement, to which special stipulations and dynamics from the directive can be applied. The criteria for compactness is population density per hectare. A suitable grid of square one-hectare cells was devised for Slovenia, with three types of settlement cells. Areas of particular agglomerations are formed by two adjoining cells whose population is most dense. The area of agglomerations is much smaller than settlement area in the register of territorial units, thus Slovene summary obligations from the directive are much smaller, as was shown in the expert guidelines for the National programme for collecting and treating waste communal and atmospheric water. These agglomerations are the basic element for planning and intervention even in other water resource planning (flood prevention measures etc. and could also be used for programmes of provision of utilities, as well as other physical development plans.

  14. Phloem Ultrastructure and Pressure Flow: Sieve-Element-Occlusion-Related Agglomerations Do Not Affect Translocation

    DEFF Research Database (Denmark)

    Froelich, Daniel R.; Mullendore, Daniel L.; Jensen, Kåre Hartvig

    2011-01-01

    feature of living sieve tubes. Live imaging of phloem flow and flow velocity measurements in individual tubes indicate that At SEOR1 agglomerations do not markedly affect or alter flow. A transmission electron microscopy preparation protocol has been generated showing sieve tube ultrastructure...

  15. A Comprehensive Quantitative Evaluation of New Sustainable Urbanization Level in 20 Chinese Urban Agglomerations

    Directory of Open Access Journals (Sweden)

    Cong Xu

    2016-01-01

    Full Text Available On 16 March 2014, the State Council of China launched its first urbanization planning initiative dubbed “National New Urbanization Planning (2014–2020” (NNUP. NNUP put forward 20 urban agglomerations and a sustainable development approach aiming to transform traditional Chinese urbanization to sustainable new urbanization. This study quantitatively evaluates the level of sustainability of the present new urbanization process in 20 Chinese urban agglomerations and provides some positive suggestions for the achievement of sustainable new urbanization. A three-level index system which is based on six fundamental elements in a city and a Full Permutation Polygon Synthetic Indicator evaluation method are adopted. The results show that China is undergoing a new urbanization process with a low level of sustainability and there are many problems remaining from traditional urbanization processes. There exists a polarized phenomenon in the urbanization of 20 urban agglomerations. Based on their own development patterns, the 20 urban agglomerations can be divided into seven categories. Every category has its own development characteristics. The analyses also show that waste of water resources, abuse of land resources, and air pollution are three big problems that are closely linked to traditional Chinese urbanization processes. To achieve sustainable new urbanization in China, four relevant suggestions and comments have been provided.

  16. Agglomeration of Celecoxib by Quasi Emulsion Solvent Diffusion Method: Effect of Stabilizer

    Directory of Open Access Journals (Sweden)

    Maryam Maghsoodi

    2016-12-01

    Full Text Available Purpose: The quasi-emulsion solvent diffusion (QESD has evolved into an effective technique to manufacture agglomerates of API crystals. Although, the proposed technique showed benefits, such as cost effectiveness, that is considerably sensitive to the choice of a stabilizer, which agonizes from a absence of systemic understanding in this field. In the present study, the combination of different solvents and stabilizers were compared to investigate any connections between the solvents and stabilizers. Methods: Agglomerates of celecoxib were prepared by QESD method using four different stabilizers (Tween 80, HPMC, PVP and SLS and three different solvents (methyl acetate, ethyl acetate and isopropyl acetate. The solid state of obtained particles was investigated by differential scanning calorimetry (DSC and Fourier transform infrared (FT-IR spectroscopy. The agglomerated were also evaluated in term of production yield, distribution of particles and dissolution behavior. Results: The results showed that the effectiveness of stabilizer in terms of particle size and particle size distribution is specific to each solvent candidate. A stabilizer with a lower HLB value is preferred which actually increased its effectiveness with the solvent candidates with higher lipophilicity. HPMC appeared to be the most versatile stabilizer because it showed a better stabilizing effect compared to other stabilizers in all solvents used. Conclusion: This study demonstrated that the efficiency of stabilizers in forming the celecoxib agglomerates by QESD was influenced by the HLB of the stabilizer and lipophilicity of the solvents.

  17. Temporal and spatial variability of urban heat island and thermal comfort within the Rotterdam agglomeration

    NARCIS (Netherlands)

    Hove, van B.; Jacobs, C.M.J.; Heusinkveld, B.G.; Elbers, J.A.; Driel, van B.L.; Holtslag, A.A.M.

    2015-01-01

    This paper reports on temporal and spatial variability of local climate and outdoor human thermal comfort within the Rotterdam agglomeration. We analyse three years of meteorological observations (2010–2012) from a monitoring network. Focus is on the atmospheric urban heat island (UHI); the

  18. A complex network approach for nanoparticle agglomeration analysis in nanoscale images

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Bruno Brandoli, E-mail: bruno.brandoli@ufms.br; Scabini, Leonardo Felipe, E-mail: leo.scabini@ufms.br; Margarido Orue, Jonatan Patrick, E-mail: jonatan.orue@ufms.br; Arruda, Mauro Santos de, E-mail: m.arruda@ufms.br; Goncalves, Diogo Nunes, E-mail: diogo.goncalves@ufms.br; Goncalves, Wesley Nunes, E-mail: wesley.goncalves@ufms.br [Federal University of Mato Grosso do Sul, CS Department (Brazil); Moreira, Raphaell, E-mail: moreira.raphaell@fu-berlin.de [Freie Universitat BerlinTakustr 3 (Germany); Rodrigues-Jr, Jose F, E-mail: junio@usp.br [University of Sao Paulo, CS Department (Brazil)

    2017-02-15

    Complex networks have been widely used in science and technology because of their ability to represent several systems. One of these systems is found in Biochemistry, in which the synthesis of new nanoparticles is a hot topic. However, the interpretation of experimental results in the search of new nanoparticles poses several challenges. This is due to the characteristics of nanoparticle images and due to their multiple intricate properties; one property of recurrent interest is the agglomeration of particles. Addressing this issue, this paper introduces an approach that uses complex networks to detect and describe nanoparticle agglomerates so to foster easier and more insightful analyses. In this approach, each detected particle in an image corresponds to a vertice and the distances between the particles define a criterion for creating edges. Edges are created if the distance is smaller than a radius of interest. Once this network is set, we calculate several discrete measures able to reveal the most outstanding agglomerates in a nanoparticle image. Experimental results using images of scanning tunneling microscopy (STM) of gold nanoparticles demonstrated the effectiveness of the proposed approach over several samples, as reflected by the separability between particles in three usual settings. The results also demonstrated efficacy for both convex and non-convex agglomerates.

  19. Evidence that pentosans and xylanase affect the re-agglomeration of the gluten network

    NARCIS (Netherlands)

    Wang, M.; Vliet, van T.; Hamer, R.J.

    2004-01-01

    In the gluten-starch separation process gluten is formed first as a result of breakdown of the gliadin-glutelin structures during mixing followed by their re-agglomeration. To date the effect of pentosans and enzymes have not been studied separately. A simple modification of TNO Glutomatic system

  20. Two-stage agglomeration of fine-grained herbal nettle waste

    Science.gov (United States)

    Obidziński, Sławomir; Joka, Magdalena; Fijoł, Olga

    2017-10-01

    This paper compares the densification work necessary for the pressure agglomeration of fine-grained dusty nettle waste, with the densification work involved in two-stage agglomeration of the same material. In the first stage, the material was pre-densified through coating with a binder material in the form of a 5% potato starch solution, and then subjected to pressure agglomeration. A number of tests were conducted to determine the effect of the moisture content in the nettle waste (15, 18 and 21%), as well as the process temperature (50, 70, 90°C) on the values of densification work and the density of the obtained pellets. For pre-densified pellets from a mixture of nettle waste and a starch solution, the conducted tests determined the effect of pellet particle size (1, 2, and 3 mm) and the process temperature (50, 70, 90°C) on the same values. On the basis of the tests, we concluded that the introduction of a binder material and the use of two-stage agglomeration in nettle waste densification resulted in increased densification work (as compared to the densification of nettle waste alone) and increased pellet density.

  1. Agglomeration, Innovation and Regional Development: Theoretical Perspectives and Meta-Analysis

    NARCIS (Netherlands)

    Groot, de Henri L.F.; Poot, Jacques; Smit, Martijn J.

    2007-01-01

    Innovation and technological change are central to the quest for regional development. In the globally-connected knowledge-driven economy, the relevance of agglomeration forces that rely on proximity continues to increase, paradoxically despite declining real costs of information, communication and

  2. Cimetières et extension urbaine en situation coloniale : le cas du cimetière musulman d’Oran (1868)

    OpenAIRE

    Benkada, Saddek

    2017-01-01

    L’auteur traite dans cet article l’évènement de la suppression du cimetière musulman d’Oran en 1868 et le considère comme une preuve, si besoin est, des logiques d’action des politiques urbaines que ce soit en France ou en Algérie en période coloniale. Pour l’auteur, la suppression du cimetière musulman d’Oran n’est qu’une reproduction du plan du baron Haussmann qui a mis la question de l’éloignement, et de la suppression, de certains cimetières au centre de sa politique urbaine d’agrandissem...

  3. Jean-Didier Urbain, 2002, Paradis verts désirs de campagne et passions résidentielles, Paris, Payot, 392 p.

    Directory of Open Access Journals (Sweden)

    Isabelle Roussel

    2003-01-01

    Full Text Available Jean-Didier Urbain, à travers cet ouvrage, applique sa vision d’anthropologue à la campagne. Cet ouvrage, facile à lire grâce à une écriture alerte, se démarque d’une vision bucolique de la verte campagne telle qu’elle a pu être véhiculée par quelques idéologues que l’auteur se plaît à fustiger au passage.Constatant les profondes mutations de la campagne française, J.D. Urbain, analyse surtout le phénomène des résidences secondaires puisque ces dernières sont plus nombreuses que les exploitat...

  4. L'agriculture urbaine : une activité créatrice d'emplois, en économie de survie : le cas de Lomé

    OpenAIRE

    Schilter, C.

    1991-01-01

    Le développement de l'agriculture urbaine à Lomé s'est accentué vers les années 1980 à la suite de la crise économique togolaise, ressentie dès la deuxième moitié des années 70, et de la politique gouvernementale menée, à la même époque, en faveur de la "Révolution verte" et de l'autosuffisance alimentaire. L'agriculture urbaine, le maraîchage plus particulièrement, est une activité fortement créatrice d'emplois qui est conditionnée par certaines contraintes. Notamment l'augmentation du nombr...

  5. Conception d’un automate cellulaire non stationnaire à base de graphe pour modéliser la structure spatiale urbaine: le modèle Remus

    OpenAIRE

    Arnaud Banos; Dominique Badariotti; Diego Moreno

    2007-01-01

    Nous proposons dans cet article une formalisation originale des automates cellulaires géographiques, à même de mieux prendre en compte grâce à une structure de graphe le voisinage irrégulier et dynamique d’entités spatiales. Le modèle Remus permet ainsi de représenter sous la forme d’un graphe mathématique les entités spatiales du bâti et les réseaux de transport urbain (graphe urbain) ; il permet aussi de calculer la distance-temps entre bâtiments par le réseau. Le modèle Remus permet l’extr...

  6. Espaces à risque et marges : méthodes d’approche des vulnérabilités urbaines à Lima et Quito

    Directory of Open Access Journals (Sweden)

    Alexis Sierra

    2009-05-01

    Full Text Available Pour aborder le risque par l’espace à Quito et à Lima, l’auteur a privilégié une lecture géopolitique qui confronte les différentes représentations sociales du risque notamment de ses causes, entre enjeux et facteurs de vulnérabilités. L’article montre comment les espaces à risques sont assimilés à des marges urbaines porteuses de stigmates. L’analyse de ces stigmates en collaboration avec les géosciences est une entrée pour comprendre la dimension sociale et politique du risque qui apparaît ainsi comme un mode de territorialisation des marges urbaines.

  7. La chronique urbaine, le notaire et le juge : l’exemple de Falcon de Bénévent (XIIe siècle)

    OpenAIRE

    Taviani-Carozzi, Huguette

    2017-01-01

    La formation et l’évolution des communes urbaines dans le Royaume d’Italie, entre le XIIe et le XIVe siècle, ont favorisé l’émergence d’une élite politique et sociale laïque, originaire du populus comme de la noblesse, qui accapara le pouvoir et fut, en même temps, soucieuse d’immortaliser par écrit ses propres gestes. Et alors que les élites communales prenaient, sans heurt dans l’ensemble, le relais du gouvernement des évêques dotés d’attributions comtales, l’historiographie urbaine échappa...

  8. Evaluation of charge and agglomeration behavior of TiO₂ nanoparticles in ecotoxicological media.

    Science.gov (United States)

    Nur, Y; Lead, J R; Baalousha, M

    2015-12-01

    The dynamic nature of nanoparticle (NP) agglomeration behavior is of paramount interest to many current studies in environmental nanoscience and nano(eco)toxicology because agglomeration affects the NP bioavailability and toxicity. The present study investigates the surface charge and agglomeration behavior of TiO2 NPs in four different ecotoxicological media (OECD algae, OECD L_variegatus, hardwater and plant media) and two different electrolytes KCl (200 mM) and CaCl2 (50 mM). TiO2 NPs were positively charged, and the zeta potential varied from +1.9 mV in hardwater (at pH7.1) to +24.5 mV in CaCl2 electrolyte (at pH7.4) in all media except algae media, where the zeta potential was -6.7 mV (at pH7.7). Despite the differences in the pH and the surface charge of TiO2 NPs in the different media, an immediate agglomeration of the NPs in all standard ecotoxicological media was observed with aggregate sizes in the micrometer scale, as the measured zeta potentials were insufficient to prevent TiO2 NP agglomeration. The isoelectric point (pHiep) of TiO2 NPs in the studied media varied in the range (6.8-7.6), which was attributed to preferential association of anions and cations to TiO2; that is the pHiep decreases with the increased concentration of Cl and increases with the increased concentrations of Na and Mg. Despite the complexity of the ecotoxicological media and the presence of a mixture of different monovalent and divalent electrolytes, the agglomeration kinetics in the media follows the DVLO theory where two distinct agglomeration rates (slow, reaction limited regime and fast, diffusion limited regime) were observable. The critical coagulation concentration (CCC) of TiO2 NPs in the ecotoxicological media varied from 17.6 to 54.0% v/v standard media in UHPW, due to differences in media pH and TiO2 NP surface charge. In the ecotoxicological media (hardwater, L-variegatus and plant), where TiO2 NPs are positively charged, the CCC decrease with the increased divalent

  9. Nucleocapsid Protein from Fig Mosaic Virus Forms Cytoplasmic Agglomerates That Are Hauled by Endoplasmic Reticulum Streaming

    Science.gov (United States)

    Ishikawa, Kazuya; Miura, Chihiro; Maejima, Kensaku; Komatsu, Ken; Hashimoto, Masayoshi; Tomomitsu, Tatsuya; Fukuoka, Misato; Yusa, Akira; Yamaji, Yasuyuki

    2014-01-01

    ABSTRACT Although many studies have demonstrated intracellular movement of viral proteins or viral replication complexes, little is known about the mechanisms of their motility. In this study, we analyzed the localization and motility of the nucleocapsid protein (NP) of Fig mosaic virus (FMV), a negative-strand RNA virus belonging to the recently established genus Emaravirus. Electron microscopy of FMV-infected cells using immunogold labeling showed that NPs formed cytoplasmic agglomerates that were predominantly enveloped by the endoplasmic reticulum (ER) membrane, while nonenveloped NP agglomerates also localized along the ER. Likewise, transiently expressed NPs formed agglomerates, designated NP bodies (NBs), in close proximity to the ER, as was the case in FMV-infected cells. Subcellular fractionation and electron microscopic analyses of NP-expressing cells revealed that NBs localized in the cytoplasm. Furthermore, we found that NBs moved rapidly with the streaming of the ER in an actomyosin-dependent manner. Brefeldin A treatment at a high concentration to disturb the ER network configuration induced aberrant accumulation of NBs in the perinuclear region, indicating that the ER network configuration is related to NB localization. Dominant negative inhibition of the class XI myosins, XI-1, XI-2, and XI-K, affected both ER streaming and NB movement in a similar pattern. Taken together, these results showed that NBs localize in the cytoplasm but in close proximity to the ER membrane to form enveloped particles and that this causes passive movements of cytoplasmic NBs by ER streaming. IMPORTANCE Intracellular trafficking is a primary and essential step for the cell-to-cell movement of viruses. To date, many studies have demonstrated the rapid intracellular movement of viral factors but have failed to provide evidence for the mechanism or biological significance of this motility. Here, we observed that agglomerates of nucleocapsid protein (NP) moved rapidly

  10. Iron Oxide Nanoparticle Agglomeration Influences Dose-Rates and Modulates Oxidative Stress Mediated Dose-Response Profiles In Vitro

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Gaurav; Kodali, Vamsi K.; Gaffrey, Matthew J.; Wang, Wei; Minard, Kevin R.; Karin, Norman J.; Teeguarden, Justin G.; Thrall, Brian D.

    2013-07-31

    Spontaneous agglomeration of engineered nanoparticles (ENPs) is a common problem in cell culture media which can confound interpretation of in vitro nanotoxicity studies. The authors created stable agglomerates of iron oxide nanoparticles (IONPs) in conventional culture medium, which varied in hydrodynamic size (276 nm-1.5 μm) but were composed of identical primary particles with similar surface potentials and protein coatings. Studies using C10 lung epithelial cells show that the dose rate effects of agglomeration can be substantial, varying by over an order of magnitude difference in cellular dose in some cases. Quantification by magnetic particle detection showed that small agglomerates of carboxylated IONPs induced greater cytotoxicity and redox-regulated gene expression when compared with large agglomerates on an equivalent total cellular IONP mass dose basis, whereas agglomerates of amine-modified IONPs failed to induce cytotoxicity or redox-regulated gene expression despite delivery of similar cellular doses. Dosimetry modelling and experimental measurements reveal that on a delivered surface area basis, large and small agglomerates of carboxylated IONPs have similar inherent potency for the generation of ROS, induction of stress-related genes and eventual cytotoxicity. The results suggest that reactive moieties on the agglomerate surface are more efficient in catalysing cellular ROS production than molecules buried within the agglomerate core. Because of the dynamic, size and density-dependent nature of ENP delivery to cells in vitro, the biological consequences of agglomeration are not discernible from static measures of exposure concentration (μg/ml) alone, highlighting the central importance of integrated physical characterisation and quantitative dosimetry for in vitro studies. The combined experimental and computational approach provides a quantitative framework for evaluating relationships between the biocompatibility of nanoparticles and their

  11. Study of atmospheric tritium transfers in lettuce: kinetic study, equilibrium and organic incorporation during a continuous atmospheric exposure; Etude des transferts du tritium atmospherique chez la laitue: Etude cinetique, etat d'equilibre et integration du tritum sous forme organique lors d'une exposition atmospherique continue

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, C.

    2009-11-30

    This thesis has explored the mechanisms of tritium 'absorption and incorporation in a human-consumed plant, lettuce (Lactuca sativa L.), due to atmospheric exposure. Foliar uptake appears to play a key role in absorption of tritium as tissue free water tritium. Whatever the development stage and the light conditions, the specific activity in tissue free water reaches that of water vapour in air in several hours. The specific activity ratio is then about 0, 4. The time to reach equilibrium in soil is over 24 hours in most cases: the specific activity ratio ranges then 0, 01 to 0, 26. Incorporation rate of tissue free water tritium as organically-bound tritium has been estimated to 0, 13 to 0, 16 % h-l in average over the growing period of the plant, but marked variations are observed during growth. In particular, a significant increase appeared at the exponential growth stage. Deposition and diffusion of tritium in soil lead to significant OBT activities in soil. Results globally indicate equilibrium between the different environmental compartments (air, soil, plant). However, some experiments have revealed high OBT concentrations regarding atmospheric level exposure and ask for a possible phenomenon of local tritium accumulation in OBT for particular conditions of exposure. (author) [French] Ce travail de these a concerne l'etude des phenomenes d'absorption et d'incorporation sous forme organique du tritium dans un vegetal de consommation courante, la laitue (Lactuca sativa L.), en reponse a une exposition atmospherique. Il apparait que la voie foliaire joue un role primordial dans l'absorption du tritium au sein de l'eau tissulaire des plants. Quels que soient le stade de developpement des plants et les conditions d'eclairement, le temps necessaire pour atteindre l'equilibre des concentrations dans l'eau libre et dans la vapeur d'eau de l'air est de plusieurs heures; le rapport des concentrations est alors de

  12. Laboratory Observations of Artificial Sand and Oil Agglomerates: Video and Velocity Data: Sea Floor Interaction Experiment Preview Video (GoPro)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Weathered oil in the surf-zone after an oil spill may mix with suspended sediments to form sand and oil agglomerates (SOA). Sand and oil agglomerates may form in...

  13. Laboratory Observations of Artificial Sand and Oil Agglomerates Video and Velocity Data: False-Floor Experiment Flow Velocity and Shear Stress

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Weathered oil in the surf-zone after an oil spill may mix with suspended sediments to form sand and oil agglomerates (SOA). Sand and oil agglomerates may form in...

  14. Sonic Enhanced Ash Agglomeration and Sulfur Capture. Technical progress report, July 1993--September 1993

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-31

    A major concern with the utilization of coal in directly fired gas turbines is the control of particulate emissions and reduction of sulfur dioxide, and alkali vapor from combustion of coal, upstream of the gas turbine. Much research and development has been sponsored on methods for particulate emissions control and the direct injection of calcium-based sorbents to reduce SO{sub 2} emission levels. The results of this research and development indicate that both acoustic agglomeration of particulates and direct injection of sorbents have the potential to become a significant emissions control strategy. The Sonic Enhanced Ash Agglomeration and Sulfur Capture program focuses upon the application of an MTCI proprietary invention (Patent No. 5,197,399) for simultaneously enhancing sulfur capture and particulate agglomeration of the combustor effluent. This application can be adapted as either a ``hot flue gas cleanup`` subsystem for the current concepts for combustor islands or as an alternative primary pulse combustor island in which slagging, sulfur capture, particulate agglomeration and control, and alkali gettering as well as NO{sub x} control processes become an integral part of the pulse combustion process. The goal of the program is to support the DOE mission in developing coal-fired combustion gas turbines. In particular, the MTCI proprietary process for bimodal ash agglomeration and simultaneous sulfur capture will be evaluated and developed. The technology embodiment of the invention provides for the use of standard grind, moderately beneficiated coal and WEM for firing the gas turbine with efficient sulfur capture and particulate emission control upstream of the turbine. The process also accommodates injection of alkali gettering material if necessary.

  15. Study of agglomeration of ice particles and of trichlorofluoromethane hydrate particles suspended in a hydrocarbon phase

    Energy Technology Data Exchange (ETDEWEB)

    Colombel, E.; Palermo, T.; Barre, L.; Gateau, P. [Inst. Francais du Petrole, Rueil Malmaison (France). Dept. of Applied Chemistry and Physico-Chemistry; Gruy, F. [Ecole Nationale Superieure des Mines, Saint Etienne (France)

    2008-07-01

    Gas hydrates may lead to pipeline blockage during oil production in offshore conditions. A study was conducted to better understand the agglomeration mechanism of gas hydrate particles in water in oil emulsions. The model system chosen to study this mechanism was ice or trichlorofluoromethane (CCl{sub 3}F) hydrate particles dispersed in xylene with asphaltenes as surfactants. The system illustrated what occurs in pipelines as produced water with oil is dispersed by surfactants that are naturally present in the oil phase. Freon was selected because it models methane behaviour very well. Both methane and freon are soluble in oil and insoluble in water. CCl{sub 3}F hydrates are stable under atmospheric pressure. As such, different techniques can be applied without being limited by high pressure conditions. The agglomeration mechanism in these particles can be modelled and compared with ice crystals. This study focused on the kinetics of agglomeration formation and mechanisms of hydrate and ice particle agglomeration in a hydrocarbon phase. Two characterization techniques were implemented in this study, notably nuclear magnetic resonance (NMR) relaxometry and rheology. The different relaxation rate for solids or liquids was used to monitor in situ the ratio between the solid and total hydrogen or fluorine as a function of time with controlled shearing conditions. NMR provided information on the formation kinetics and the conversion rate of water in ice crystals. The rest of the study focused on the formation of Freon hydrate crystals. The study confirmed that the physico-chemistry of the water/oil interface has an important role in agglomeration. 9 refs., 5 tabs., 18 figs.

  16. Controlling Agglomeration of Protein Aggregates for Structure Formation in Liquid Oil: A Sticky Business.

    Science.gov (United States)

    de Vries, Auke; Lopez Gomez, Yuly; Jansen, Bas; van der Linden, Erik; Scholten, Elke

    2017-03-22

    Proteins are known to be effective building blocks when it comes to structure formation in aqueous environments. Recently, we have shown that submicron colloidal protein particles can also be used to provide structure to liquid oil and form so-called oleogels ( de Vries , A. J. Colloid Interface Sci. 2017 , 486 , 75 - 83 ) . To prevent particle agglomeration, a solvent exchange procedure was used to transfer the aggregates from water to the oil phase. The aim of the current paper was to elucidate on the enhanced stability against agglomeration of heat-set whey protein isolate (WPI) aggregates to develop an alternative for the solvent exchange procedure. Protein aggregates were transferred from water to several solvents differing in polarity to investigate the effect on agglomeration and changes in protein composition. We show that after drying protein aggregates by evaporation from solvents with a low polarity (e.g., hexane), the protein powder shows good dispersibility in liquid oil compared to powders dried from solvents with a high polarity. This difference in dispersibility could not be related to changes in protein composition or conformation but was instead related to the reduction of attractive capillary forces between the protein aggregates during drying. Following another route, agglomeration was also prevented by applying high freezing rates prior to freeze-drying. The rheological properties of the oleogels prepared with such freeze-dried protein aggregates were shown to be similar to that of oleogels prepared using a solvent exchange procedure. This Research Article provides valuable insights in how to tune the drying process to control protein agglomeration to allow for subsequent structure formation of proteins in liquid oil.

  17. Characterisation of the de-agglomeration effects of bovine serum albumin on nanoparticles in aqueous suspension.

    Science.gov (United States)

    Tantra, Ratna; Tompkins, Jordan; Quincey, Paul

    2010-01-01

    This paper describes the use of nanoparticle characterisation tools to evaluate the interaction between bovine serum albumin (BSA) and dispersed nanoparticles in aqueous media. Dynamic light scattering, zeta-potential measurements and scanning electron microscopy were used to probe the state of zinc oxide (ZnO) and titanium dioxide (TiO(2)) nanoparticles in the presence of various concentrations of BSA, throughout a three-day period. BSA was shown to adhere to ZnO but not to TiO(2). The adsorption of BSA led to subsequent de-agglomeration of the sub-micron ZnO clusters into smaller fragments, even breaking them up into individual isolated nanoparticles. We propose that certain factors, such as adsorption kinetics of BSA on to the surface of ZnO, as well as the initial agglomerated state of the ZnO, prior to BSA addition, are responsible for promoting the de-agglomeration process. Hence, in the case of TiO(2) we see no de-agglomeration because: (a) the nanoparticles are more highly agglomerated to begin with and (b) BSA does not adsorb effectively on the surface of the nanoparticles. The zeta-potential results show that, for either ZnO or TiO(2), the presence of BSA resulted in enhanced stability. In the case of ZnO, the enhanced stability is limited to BSA concentrations below 0.5 wt.%. Steric and electrostatic repulsion are thought to be responsible for improved stability of the dispersion.

  18. CONSOLIDATION OF K BASIN SLUDGE DATA AND EXPERIENCES ON AGGLOMERATE FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    HILL SR

    2010-06-10

    The formation of high sludge strength agglomerates is a key concern to the Sludge Treatment Project (STP) to ensure the sludge can be retrieved after planned storage for up to 10 years in Sludge Transport and Storage Containers (STSC) at T Plant. This report addresses observations of agglomerate formation, conditions that the data shows lead to agglomeration, the frequency of agglomerate formation and postulated physiochemical mechanisms that may lead to agglomeration. Although the exact underlying chemistry of K Basin sludge agglomerate formation is not known, the factors that lead to agglomeration formation, based on observations, are as follows: (1) High Total Uranium Content (i.e., sample homogeneity and influence from other constituents); (2) Distribution of Uranium Phases (i.e., extent of conversion from uraninite to uranium oxide hydroxide compounds); (3) Sample Dry-out (loss of cover water); (4) Elevated temperature; (5) Solubility ofU(IV) phases vs. U(VI) phases; and (6) Long storage times. Agglomerated sludge has occurred infrequently and has only been observed in four laboratory samples, five samples subjected to hydrothermal testing (performed for 7 to 10 hours at {approx}185 C and 225 psig), and indirectly during six sampling events in the KE Basin. In the four laboratory samples where agglomerates were observed, the agglomerates exhibited high shear strength and the sample container typically had to be broken to remove the solids. The total uranium content (dry basis) for the four samples (KE Pit, KC-2/3 SS, KC-2/3 M250 and 96-13) were {approx}8 wt%, {approx}59.0 wt%, 68.3 wt% and 82 wt%. The agglomerates that were present during the six sampling events were undoubtedly disturbed and easily broken apart during sample collection, thus no agglomerates were observed in subsequent laboratory analyses. The highest shear strengths measured for K Basin sludge samples were obtained after hydrothermal treatment (7 to 10 hr at 185 C) of high-uranium-content KE

  19. Desulfurization and de-ashing of a mixture of subbituminous coal and gangue minerals by selective oil agglomeration

    Energy Technology Data Exchange (ETDEWEB)

    Ayhan, F.D. [Dicle University, Diyarbakir (Turkey). Dept. of Mining Engineering

    2009-11-15

    The aim of this study was to investigate desulfurization and de-ashing of a mixture of subbituminous coal and gangue minerals by the agglomeration method. For this purpose, experimental studies were conducted on a mixture containing subbituminous coal, pyrite, quartz and calcite. The effects of some parameters that markedly influence the effectiveness of selective oil agglomeration, such as solid concentration, pH, bridging liquid type and concentration, and depressant type and amount, were investigated. Agglomeration results showed that the usage of various depressants (Na{sub 2}SiO{sub 3}, FeCl3, corn starch, wheat starch) in the agglomeration medium has a positive effect on the reduction of ash and total sulfur content of agglomerates. It was found that an agglomerate product containing 3.03% total sulfur and 25.01% ash with a total sulfur reduction of 56.71% was obtained from a feed that contained 7% total sulfur and 43.58% ash when FeCl{sub 3} was used in the agglomeration medium.

  20. Disentangling the effects of polymer coatings on silver nanoparticle agglomeration, dissolution, and toxicity to determine mechanisms of nanotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Zook, Justin M., E-mail: jzook@nist.gov; Halter, Melissa D.; Cleveland, Danielle; Long, Stephen E. [National Institute of Standards and Technology, Material Measurement Laboratory (United States)

    2012-10-15

    Silver nanoparticles (AgNPs) are frequently coated with a variety of polymers, which may affect various interdependent mechanisms of toxicity or antimicrobial action, including agglomeration and dissolution rates. Here, we systematically measure how citrate, dextran, 5 and 20 kDa poly(ethylene glycol) (PEG), and poly(vinyl pyrrolidone) coatings affect AgNP agglomeration, dissolution, and toxicity. In addition, to disentangle the coatings' effects on agglomeration from their other effects, we produce multiple stable agglomerate sizes of several of the coated {approx}23 nm AgNPs ranging from singly-dispersed to mean agglomerate sizes of several hundred nanometers. These dispersions allow us to independently study the effects of agglomeration and polymer coating on dissolution rate and hemolytic toxicity. We find that both hemolytic toxicity and dissolution rate are highest for the 5 kDa PEG coating, and toxicity and dissolution rate decrease significantly with increasing agglomerate size independent of coating. This correlation between toxicity and dissolution rate suggests that both polymer coating and agglomeration may affect hemolytic toxicity largely through their effects on dissolution. Because both the AgNP dissolution rate and hemolysis decrease only moderately compared to the large increases in agglomerate size, AgNPs' hemolytic toxicity may be caused by their large surface area and consequently high dissolution rate, rather than from other size-specific effects. At the silver concentrations used in this work, silver dissolved from AgNPs is expected to be primarily in the form of AgCl NPs, which are therefore more likely than Ag{sup +} ions to be the primary drivers of hemolytic toxicity. In addition, all AgNPs we tested are much more toxic to horse red blood cells than sheep red blood cells, highlighting the complexity of toxic responses and the need to test toxicity in multiple biological systems.

  1. Disentangling the effects of polymer coatings on silver nanoparticle agglomeration, dissolution, and toxicity to determine mechanisms of nanotoxicity

    Science.gov (United States)

    Zook, Justin M.; Halter, Melissa D.; Cleveland, Danielle; Long, Stephen E.

    2012-10-01

    Silver nanoparticles (AgNPs) are frequently coated with a variety of polymers, which may affect various interdependent mechanisms of toxicity or antimicrobial action, including agglomeration and dissolution rates. Here, we systematically measure how citrate, dextran, 5 and 20 kDa poly(ethylene glycol) (PEG), and poly(vinyl pyrrolidone) coatings affect AgNP agglomeration, dissolution, and toxicity. In addition, to disentangle the coatings' effects on agglomeration from their other effects, we produce multiple stable agglomerate sizes of several of the coated 23 nm AgNPs ranging from singly-dispersed to mean agglomerate sizes of several hundred nanometers. These dispersions allow us to independently study the effects of agglomeration and polymer coating on dissolution rate and hemolytic toxicity. We find that both hemolytic toxicity and dissolution rate are highest for the 5 kDa PEG coating, and toxicity and dissolution rate decrease significantly with increasing agglomerate size independent of coating. This correlation between toxicity and dissolution rate suggests that both polymer coating and agglomeration may affect hemolytic toxicity largely through their effects on dissolution. Because both the AgNP dissolution rate and hemolysis decrease only moderately compared to the large increases in agglomerate size, AgNPs' hemolytic toxicity may be caused by their large surface area and consequently high dissolution rate, rather than from other size-specific effects. At the silver concentrations used in this work, silver dissolved from AgNPs is expected to be primarily in the form of AgCl NPs, which are therefore more likely than Ag+ ions to be the primary drivers of hemolytic toxicity. In addition, all AgNPs we tested are much more toxic to horse red blood cells than sheep red blood cells, highlighting the complexity of toxic responses and the need to test toxicity in multiple biological systems.

  2. Effects of Al(OH)O nanoparticle agglomerate size in epoxy resin on tension, bending, and fracture properties

    Energy Technology Data Exchange (ETDEWEB)

    Jux, Maximilian, E-mail: maximilian.jux@dlr.de [TU Braunschweig, Institute of Adaptronic and Functional Integration (IAF) (Germany); Finke, Benedikt [TU Braunschweig, Institute for Particle Technology (IPAT) (Germany); Mahrholz, Thorsten [DLR Braunschweig, Institute of Composite Structures and Adaptive Systems (FA) (Germany); Sinapius, Michael [TU Braunschweig, Institute of Adaptronic and Functional Integration (IAF) (Germany); Kwade, Arno; Schilde, Carsten [TU Braunschweig, Institute for Particle Technology (IPAT) (Germany)

    2017-04-15

    Several epoxy Al(OH)O (boehmite) dispersions in an epoxy resin are produced in a kneader to study the mechanistic correlation between the nanoparticle size and mechanical properties of the prepared nanocomposites. The agglomerate size is set by a targeted variation in solid content and temperature during dispersion, resulting in a different level of stress intensity and thus a different final agglomerate size during the process. The suspension viscosity was used for the estimation of stress energy in laminar shear flow. Agglomerate size measurements are executed via dynamic light scattering to ensure the quality of the produced dispersions. Furthermore, various nanocomposite samples are prepared for three-point bending, tension, and fracture toughness tests. The screening of the size effect is executed with at least seven samples per agglomerate size and test method. The variation of solid content is found to be a reliable method to adjust the agglomerate size between 138–354 nm during dispersion. The size effect on the Young’s modulus and the critical stress intensity is only marginal. Nevertheless, there is a statistically relevant trend showing a linear increase with a decrease in agglomerate size. In contrast, the size effect is more dominant to the sample’s strain and stress at failure. Unlike microscaled agglomerates or particles, which lead to embrittlement of the composite material, nanoscaled agglomerates or particles cause the composite elongation to be nearly of the same level as the base material. The observed effect is valid for agglomerate sizes between 138–354 nm and a particle mass fraction of 10 wt%.

  3. FUNCTIONAL, SECTORAL AND REGIONAL TRANSFORMATION OF THE ECONOMY OF THE MISKOLC AGGLOMERATION REVISITED

    Directory of Open Access Journals (Sweden)

    Andrea KRISTÓF

    2017-04-01

    Full Text Available Among the segments of economic development and shifts in the Miskolc agglomeration the present study introduces some characteristics of the functional, sectoral and regional differentiation of economic transformation. The functional, sectoral and geographical distribution of business corporations in the 35 settlements of the Miskolc agglomeration in 2016 may help to interpret and assess economic processes adapted to local characteristics in the past quarter-century. During the research, only those operating businesses were considered that had net sales of 20 million HUF or more in 2015. An empirical study of 640 active businesses in 35 settlements reveals the regional inequalities and sectoral concentration of the economy. The intensity of the spatial structure of the economy is uneven within the Miskolc agglomeration and spatial specialization can also be observed in the economic hinterland of Miskolc. The economic development induced significant changes in the spatial structure of three towns (Felsőzsolca, Nyékládháza, and Alsózsolca. Services (e.g. personal, distributive, and services for other businesses as well as commerce, logistics and leisure functions concentrated in these towns strengthened their positions in the spatial structure. In addition, the technological and industrial parks of these towns are playing an increasing role. However, the towns of the agglomeration cannot or can hardly be regarded as economic competitors of Miskolc, i.e. the urban region has not become polycentric, and the inhabitants of these towns are not totally independent of Miskolc. In the case of Sajóbábony (due to its special situation and Szikszó (despite its economic recovery the functional, sectoral and regional transformation is not clear yet. Of the villages, only four (Kistokaj, Mályi, Szirmabesenyő, Hernádnémeti could significantly improve their economic positions, and were able to rival the dynamically transforming three towns of the

  4. Formes spatiales d’expansion urbaine et le rôle des communautés non musulmanes à l’époque des Réformes.

    Directory of Open Access Journals (Sweden)

    Alexandra Yerolympos

    2012-01-01

    Full Text Available Le présent texte étudie les formes d’expansion urbaine dans les provinces européennes de l’Empire ottoman depuis la moitié du xixe siècle. Dans le cadre des réformes entreprises par l’Empire, l’octroi de droits civiques et politiques à tous les sujets ottomans, le “décollage économique” et la croissance démographique encouragent l’émergence de nouveaux comportements socio-économiques : grâce à la réforme du droit foncier et l’afflux d’investissements dans le secteur immobilier de la part des particuliers, des communautés ou des organismes publics, l’espace urbain est réaménagé et “modernisé”. L’expansion des villes préoccupait les officiers ottomans de bonne heure. La première réglementation moderne d’urbanisme mise en place entre 1848 et 1891 définit les règles selon lesquelles de nouveaux quartiers urbains peuvent être formés. D’après des études sur les villes côtières, ainsi que sur la plupart des villes de l’intérieur des provinces européennes de l’Empire, l’accroissement urbain s’accompagne d’une forte activité de groupes minoritaires pour leur installation résidentielle dans de nouveaux quartiers, très souvent encouragée par les autorités locales. L’installation prend des formes variées, parfois créant des quartiers non pas étanches mais à dominante chrétienne ou juive, parfois parfaitement mixtes. Les variantes rencontrées évoquent les particularités historiques et géographiques de chaque ville ; elles s’expliquent aussi par des stratégies des autorités locales et des besoins ou aspirations des groupes sociaux et ethniques qui les revendiquent. On étudiera l’extension planifiée de trois villes côtières et fortifiées : Volos et Kavala, petites villes dotées d’une importante fonction portuaire où la communauté grecque orthodoxe suscita la création de nouveaux quartiers ; Salonique (Thessalonique qui connut une expansion

  5. Influence of germanium on thermal dewetting and agglomeration of the silicon template layer in thin silicon-on-insulator

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, P P; Yang, B; Rugheimer, P P; Roberts, M M; Savage, D E; Lagally, M G [University of Wisconsin, Madison, WI 53706 (United States); Liu Feng, E-mail: lagally@engr.wisc.ed [University of Utah, Salt Lake City, UT 84112 (United States)

    2009-09-07

    We investigate the influence of heteroepitaxially grown Ge on the thermal dewetting and agglomeration of the Si(0 0 1) template layer in ultrathin silicon-on-insulator (SOI). We show that increasing Ge coverage gradually destroys the long-range ordering of 3D nanocrystals along the (1 3 0) directions and the 3D nanocrystal shape anisotropy that are observed in the dewetting and agglomeration of pure SOI(0 0 1). The results are qualitatively explained by Ge-induced bond weakening and decreased surface energy anisotropy. Ge lowers the dewetting and agglomeration temperature to as low as 700 {sup 0}C.

  6. Investigation of coalescence kinetics of microcristalline cellulose in fluidised bed spray agglomeration: experimental studies and modelling approach

    Directory of Open Access Journals (Sweden)

    M. Peglow

    2005-06-01

    Full Text Available In this paper a model for fluidized bed spray agglomeration is presented. To describe the processes of heat and mass transfer, a physical based model is derived. The model takes evaporation process from the wetted particles as well as the effects of transfer phenomena between suspension gas and bypass gas into account. The change of particle size distribution during agglomeration, modeled by population balances, is linked to the heat and mass transfer model. A new technique is derived to extract agglomeration and nucleation rates from experimental data. Comparisons of experiments and simulations are presented.

  7. Selected aspects of the methodology of a household interview survey on an urban agglomeration scale with regard to its services

    Directory of Open Access Journals (Sweden)

    Renata ŻOCHOWSKA

    2017-06-01

    Full Text Available The article presents the essential issues and algorithm of the methodology of a four-step transportation model, which was constructed in order to carrying out a household interview survey. The results of this research are source data for determining the travel behaviour of the users of transportation systems, including intelligent transport systems (ITS. The presented issues regarding the survey methodology also concern the specifics of the study area, an urban agglomeration area. The examples particularly relate to an urban agglomeration with the nature of a conurbation, namely, the Upper Silesian Agglomeration in Poland.

  8. XRD and DTA Analysis of Developed Agglomerated Fluxes for Submerged Arc Welding

    Directory of Open Access Journals (Sweden)

    Ajay Kumar

    2013-01-01

    Full Text Available A unique study of structural and chemical analysis of crystalline phases in developed agglomerated fluxes was carried out. Thirty-two fluxes were developed by using a mixture of oxides, halides, carbonates, silicates, and ferroalloys for submerged arc welding. The present paper focuses on only ten (out of thirty-two fluxes which were analyzed by X-ray diffraction (XRD to know the different types of oxides formed and changed in oxidation number of metallic centers after sintering process at around 850∘C. To know the effect of temperature over phase transformation and melting of different compounds, differential thermal analysis (DTA was carried out from 1000 to 1400∘C. This study aims to know the quantity of ions present (percentage and melting behavior of developed agglomerated fluxes for submerged arc welding process.

  9. Agglomeration and Dendritic Growth of Cu/Ti/Si Thin Film

    Directory of Open Access Journals (Sweden)

    Qi-jing Lin

    2014-01-01

    Full Text Available Agglomeration and the transformation from random fractal to dendritic growth have been observed during Cu/Ti/Si thin film annealing. The experimental results show that the annealing temperature, film thickness, and substrate thickness influenced the agglomeration and dendritic growth. Multifractal spectrum is used to characterize the surface morphology quantificationally. The shapes of the multifractal spectra are hook-like to the left. Value of Δα increases with the annealing temperature rising, and Δf increases from 500°C to 700°C but reduces from 700°C to 800°C. The dendritic patterns with symmetrical branches are generated in the surfaces when the thin films were annealed at 800°C.

  10. Discrete population balance models of random agglomeration and cleavage in polymer pyrolysis

    Directory of Open Access Journals (Sweden)

    John E. J. Staggs

    2017-05-01

    Full Text Available The processes of random agglomeration and cleavage (both of which are important for the development of new models of polymer combustion, but are also applicable in a wide range of fields including atmospheric physics, radiation modelling and astrophysics are analysed using population balance methods. The evolution of a discrete distribution of particles is considered within this framework, resulting in a set of ordinary differential equations for the individual particle concentrations. Exact solutions for these equations are derived, together with moment generating functions. Application of the discrete Laplace transform (analogous to the Z-transform is found to be effective in these problems, providing both exact solutions for particle concentrations and moment generating functions. The combined agglomeration-cleavage problem is also considered. Unfortunately, it has been impossible to find an exact solution for the full problem, but a stable steady state has been identified and computed.

  11. Laboratory observations of artificial sand and oil agglomerates video and velocity data

    Science.gov (United States)

    Jenkins, Robert; Dalyander, P. Soupy; Penko, Allison; Long, Joseph W.; Nelson, Timothy

    2017-01-01

    The U.S. Geological Survey conducted experiments during March of 2014 to expand the available data on sand and oil agglomerate motion; test shear stress based incipient motion parameterizations in a controlled, laboratory setting; and directly observe sand and oil agglomerate exhumation and burial processes. Experiments were carried out at the Naval Research Laboratory, Stennis Space Center, Stennis, Mississippi using a small-oscillatory flow tunnel. HD Video data was collected by two Canon 7D DSLR cameras. 3D flow velocity data was captured by a Vectrino acoustic Doppler current profiler. Additional video data was captured by a GoPro camera placed within the small-oscillatory flow tunnel. For the false-floor incipient motion experiment, movies which combine video data, flow velocity data, calculations of shear stress, and the instant of incipient motion were created. For the movable bed sea-floor interaction experiment, movies which combine video data and flow velocity data were created.

  12. A Complex Network Approach for Nanoparticle Agglomeration Analysis in Nanoscale Images

    CERN Document Server

    Brandoli, Bruno; Orue, Jonathan; Arruda, Mauro; Goncalves, Diogo; Goncalves, Wesley; Moreira, Raphaell; Rodrigues-Jr, Jose

    2016-01-01

    Complex networks have been widely used in science and technology because of their ability to represent several systems. One of these systems is found in Biochemistry, in which the synthesis of new nanoparticles is a hot topic. However, the interpretation of experimental results in the search of new nanoparticles poses several challenges. This is due to the characteristics of nanoparticles images and due to their multiple intricate properties; one property of recurrent interest is the agglomeration of particles. Addressing this issue, this paper introduces an approach that uses complex networks to detect and describe nanoparticle agglomerates so to foster easier and more insightful analyses. In this approach, each detected particle in an image corresponds to a vertice and the distances between the particles define a criterion for creating edges. Edges are created if the distance is smaller than a radius of interest. Once this network is set, we calculate several discrete measures able to reveal the most outsta...

  13. Internal migration, regional labor markets and the role of agglomeration economies

    DEFF Research Database (Denmark)

    Mitze, Timo Friedel; Schmidt, Torben Dall

    2015-01-01

    We analyze the determinants and regional implications of internal migration flows across Danish municipalities in 2006–2012. Besides assessing the role of labor market and housing market factors in driving a region’s net migration rate, we particularly focus on agglomeration factors identified...... are indeed key drivers of internal migration flows in Denmark. That is, while we obtain mixed evidence with regard to the role of traditional labor and housing market variables, most of the included proxies for agglomeration economies such as the region’s population density, patent intensity, endowment...... with human capital as well as the region’s employment share of knowledge-intensive services are positively correlated with the region’s net in-migration rate. Regarding the regional implications of internal migration flows, the results hint at a process of cumulative causation for the time period of analysis...

  14. A Mathematical Model for Carbothermic Reduction of Dust-Carbon Composite Agglomerates

    Science.gov (United States)

    Kuwauchi, Yuki

    A mathematical model to simulate the reaction kinetics of dust-carbon composite agglomerates in an RHF was developed. Major chemical, thermal and physical phenomena taking place during RHF treatment were formulated and the corresponding equations were solved to yield the trend of solid composition, temperature and gas composition of the agglomerates. The model calculation results indicate that the pellet reduction is accelerated by the reducing gas from high-volatile reductants if the gas is released after the pellet temperature is sufficiently high for reduction. The reduction of zinc oxide can also be represented using the model by implementing its small particle size caused by the inherent vaporization/re-oxidization process that zinc comes through in a melter. It was demonstrated that the proposed model can be used as an engineering tool to determine the optimum operating conditions for the RHF process to promote recycling a wide range of waste materials.

  15. Single coating of zinc ferrite renders magnetic nanomotors therapeutic and stable against agglomeration.

    Science.gov (United States)

    Venugopalan, Pooyath Lekshmy; Jain, Shilpee; Shivashankar, Srinivasrao; Ghosh, Ambarish

    2018-02-01

    Magnetic nanomotors with integrated theranostic capabilities can revolutionize biomedicine of the future. Typically, these nanomotors contain ferromagnetic materials, such that small magnetic fields can be used to maneuver and localize them in fluidic or gel-like environments. Motors with large permanent magnetic moments tend to agglomerate, which limits the scalability of this otherwise promising technology. Here, we demonstrate the application of a microwave-synthesized ferrite layer to reduce the agglomeration of helical ferromagnetic nanomotors by an order of magnitude, which allows them to be stored in a colloidal suspension for longer than six months and subsequently be manoeuvred with undiminished performance. The ferrite layer also rendered the nanomotors suitable as magnetic hyperthermia agents, as demonstrated by their cytotoxic effects on cancer cells. The two functionalities were inter-related since higher hyperthermia efficiency required a denser suspension, both of which were achieved in a single microwave-synthesized ferrite coating.

  16. Modelling and simulation of flow and agglomeration in deep veins valves using discrete multi physics.

    Science.gov (United States)

    Ariane, M; Wen, W; Vigolo, D; Brill, A; Nash, F G B; Barigou, M; Alexiadis, A

    2017-10-01

    The hemodynamics in flexible deep veins valves is modelled by means of discrete multi-physics and an agglomeration algorithm is implemented to account for blood accrual in the flow. Computer simulations of a number of valves typologies are carried out. The results show that the rigidity and the length of the valve leaflets play a crucial role on both mechanical stress and stagnation in the flow. Rigid and short membranes may be inefficient in preventing blood reflux, but reduce the volume of stagnant blood potentially lowering the chances of thrombosis. Additionally, we also show that in venous valves, cell agglomeration is driven by stagnation rather than mechanical stress. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Agglomeration of Non-metallic Inclusions at the Steel/Ar Interface: Model Application

    Science.gov (United States)

    Mu, Wangzhong; Dogan, Neslihan; Coley, Kenneth S.

    2017-08-01

    Inclusion agglomeration is an important element in several industrial problems during steelmaking, such as nozzle clogging. In parallel work by the authors, a revised Kralchevsky-Paunov model has been established and the performance of this model has been validated against the experimental data from in-situ observations using confocal laser scanning microscopy. In this work, the revised model has been applied to quantitatively evaluate the attractive capillary force for the agglomeration of various inclusions at the interface between Ar and liquid iron/steel. A parametric study of the effects on the capillary force of the inclusion density, contact angle between the inclusion and liquid steel, and the surface tension of the liquid metal are quantitatively investigated. The results show that inclusion density and contact angle have a more marked effect on the capillary force than surface tension of liquid metal. Moreover, the inclusion agglomeration behavior in the liquid iron/steel matrix is discussed. The coagulation coefficient of various inclusions is calculated. Both the calculation results of the attractive capillary force of inclusions at the interface between Ar and liquid iron/steel and coagulation coefficient of inclusions in the liquid iron/steel matrix can offer a close agreement; moreover, the order of magnitude of inclusion agglomeration tendency is suggested. By using the coagulation coefficient, the inclusion collision volume and collision rate are calculated and the effects of inclusion composition, size, and number density are investigated. The evaluation results show that the tendency for affecting inclusion collision is inclusion number density > inclusion size > inclusion composition.

  18. Reproductive strategies of citizens in urban agglomeration (the case of Moscow

    Directory of Open Access Journals (Sweden)

    E. N. Novosyelova

    2015-01-01

    Full Text Available Current article overlooks the strategies of reproductive behavior of citizens in urban agglomeration (the case of Moscow. The author analyzes how life in a big city influences the reproductive patterns, reveals the link between the urban lifestyle of the majority of the planet’s population and the crisis tendencies of family changes, such as late marriages and fertility, increase of proportion of childlessness and childfree, etc.

  19. Micro-Flow Imaging as a quantitative tool to assess size and agglomeration of PLGA microparticles.

    Science.gov (United States)

    van Beers, Miranda M C; Slooten, Cees; Meulenaar, Jelte; Sediq, Ahmad S; Verrijk, Ruud; Jiskoot, Wim

    2017-08-01

    The purpose of this study was to explore the potential of flow imaging microscopy to measure particle size and agglomeration of poly(lactic-co-glycolic acid) (PLGA) microparticles. The particle size distribution of pharmaceutical PLGA microparticle products is routinely determined with laser diffraction. In our study, we performed a unique side-by-side comparison between MFI 5100 (flow imaging microscopy) and Mastersizer 2000 (laser diffraction) for the particle size analysis of two commercial PLGA microparticle products, i.e., Risperdal Consta and Sandostatin LAR. Both techniques gave similar results regarding the number and volume percentage of the main particle population (28-220μm for Risperdal Consta; 16-124μm for Sandostatin LAR). MFI additionally detected a 'fines' population (<28μm for Risperdal Consta; <16μm for Sandostatin LAR), which was overlooked by Mastersizer. Moreover, MFI was able to split the main population into 'monospheres' and 'agglomerates' based on particle morphology, and count the number of particles in each sub-population. Finally, we presented how MFI can be applied in process development of risperidone PLGA microparticles and to monitor the physical stability of Sandostatin LAR. These case studies showed that MFI provides insight into the effect of different process steps on the number, size and morphology of fines, monospheres and agglomerates as well as the extent of microparticle agglomeration after reconstitution. This can be particularly important for the suspendability, injectability and release kinetics of PLGA microparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Social aspects of the suburbanisation stage in the agglomeration of Warsaw

    Directory of Open Access Journals (Sweden)

    Andrzej Lisowski

    2004-01-01

    Full Text Available The study identifies the changes in the living conditions in the Agglomeration of Warsaw1995-2001 and their impact upon the decentralisation process of the population and businesses.It has been confirmed that spatial re-distribution of people and jobs in suburbanzone is affected by the living conditions in the areas, but the impact of land rent seems to bealso important.

  1. Development of clean coal and clean soil technologies using advanced agglomeration technologies

    Energy Technology Data Exchange (ETDEWEB)

    Ignasiak, B.; Pawlak, W.; Szymocha, K.; Marr, J.

    1990-04-01

    The specific objectives of the bituminous coal program were to explore and evaluate the application of advanced agglomeration technology for: (1)desulphurization of bituminous coals to sulphur content acceptable within the current EPA SO{sub 2} emission guidelines; (2) deashing of bituminous coals to ash content of less than 10 percent; and (3)increasing the calorific value of bituminous coals to above 13,000 Btu/lb. (VC)

  2. Investigation of the production of wet agglomerates of couscous grains using a fluidized bed granulator

    OpenAIRE

    Cuq, Bernard; Ruiz, Thierry

    2017-01-01

    Mastering the industrial processes in which wheat powders are used to produce couscous is still partly based on practical industrial experience and empirical knowledge. Wet agglomeration, rolling, cooking, drying and screening are the main unit operations which are sequentially involved in the couscous grain production. Granulation is the main step that determines the production yield and the final size and shape of the couscous grain. Control of granule size distribution after the wet granul...

  3. Reengineering of the human pyruvate dehydrogenase complex: from disintegration to highly active agglomerates.

    Science.gov (United States)

    Guo, Jin; Hezaveh, Samira; Tatur, Jana; Zeng, An-Ping; Jandt, Uwe

    2017-02-20

    The pyruvate dehydrogenase complex (PDC) plays a central role in cellular metabolism and regulation. As a metabolite-channeling multi-enzyme complex it acts as a complete nanomachine due to its unique geometry and by coupling a cascade of catalytic reactions using 'swinging arms'. Mammalian and specifically human PDC (hPDC) is assembled from multiple copies of E1 and E3 bound to a large E2/E3BP 60-meric core. A less restrictive and smaller catalytic core, which is still active, is highly desired for both fundamental research on channeling mechanisms and also to create a basis for further modification and engineering of new enzyme cascades. Here, we present the first experimental results of the successful disintegration of the E2/E3BP core while retaining its activity. This was achieved by C-terminal α-helixes double truncations (eight residues from E2 and seven residues from E3BP). Disintegration of the hPDC core via double truncations led to the formation of highly active (approximately 70% of wildtype) apparently unordered clusters or agglomerates and inactive non-agglomerated species (hexamer/trimer). After additional deletion of N-terminal 'swinging arms', the aforementioned C-terminal truncations also caused the formation of agglomerates of minimized E2/E3BP complexes. It is likely that these 'swinging arm' regions are not solely responsible for the formation of the large agglomerates. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  4. Spherical agglomerates of pure drug nanoparticles for improved pulmonary delivery in dry powder inhalers

    Science.gov (United States)

    Hu, Jun; Dong, Yuancai; Pastorin, Giorgia; Ng, Wai Kiong; Tan, Reginald B. H.

    2013-04-01

    The aim of this study was to produce micron-sized spherical agglomerates of pure drug nanoparticles to achieve improved aerosol performance in dry powder inhalers (DPIs). Sodium cromoglicate was chosen as the model drug. Pure drug nanoparticles were prepared through a bottom-up particle formation process, liquid antisolvent precipitation, and then rapidly agglomerated into porous spherical microparticles by immediate (on-line) spray drying. Nonporous spherical drug microparticles with similar geometric size distribution were prepared by conventional spray drying of the aqueous drug solution, which together with the mechanically micronized drug particles were used as the control samples. The three samples were characterized by field emission scanning electron microscopy, laser diffraction, Brunauer-Emmett-Teller analysis, density measurement, powder X-ray diffraction, and in vitro aerosol deposition measurement with a multistage liquid impinger. It was found that drug nanoparticles with a diameter of 100 nm were precipitated and agglomerated into highly porous spherical microparticles with a volume median diameter ( D 50 %) of 2.25 ± 0.08 μm and a specific surface area of 158.63 ± 3.27 m2/g. In vitro aerosol deposition studies showed the fine particle fraction of such spherical agglomerates of drug nanoparticles was increased by more than 50 % in comparison with the control samples, demonstrating significant improvements in aerosol performance. The results of this study indicated the potential of the combined particle engineering process of liquid antisolvent precipitation followed by immediate (on-line) spray drying in the development of novel DPI drug products with improved aerosol performance.

  5. The Evolving Concept of Retail Attractiveness: what makes retail agglomerations attractive when customers shop at them?

    OpenAIRE

    Teller, C; Reutterer, T

    2008-01-01

    This paper attempts to contribute to a more thorough understanding of the on-site (‘in vivo’) evaluation of retail agglomerations once shoppers have already made their destination choices. To address this issue, a modification of more conventional concepts of retail attractiveness that considers situational contexts is proposed and empirically tested. The survey comprised more than 2,000 on-site interviews of customers of an inner city shopping street and a competing peripheral shopping mall....

  6. Bed agglomeration in biomass fueled CFB-boilers; Sintring av baeddmaterial vid biobraensleeldning i CFB

    Energy Technology Data Exchange (ETDEWEB)

    Zintl, F. [TPS Termiska Processer AB, Nykoeping (Sweden)

    1997-02-01

    In fluidized-bed boilers fired with solid fuels operational problems caused by spontaneous defluidization are sometimes observed. This bed agglomeration can be caused by sintering phenomena where fuel components and/or bed material may be involved. In serious cases the problems can lead to expensive operation breaks. The objective in this project was to show whether this type of operational problems can be minimized by choice of other than conventional bed materials. The study was carried out as model experiments in a larger laboratory scale. In a fluidized bed fired with propane a number of both well known and more unusual bed materials were tried out. The choice of bed materials included some common sands (silver and quartz sand) and, as possible alternatives, olivine sand, zirconium sand, calcined dolomite and the synthetic materials sintered magnesite (MgO) and mullite (alumina silicate). The model experiments were started at about 700 deg C and the temperature then raised until an irreversible bed agglomeration was observed, or to a maximum of 1100 deg C. The most promising results were obtained with calcined dolomite, being an active bed material. With this material no irreversible agglomerations were observed at all. The expensive synthetic materials sintered magnesite and mullite and the zirconium sand turned out as the next best. Olivine sand, on the other hand, showed a clear sensitivity to physical agglomeration and some sensitivity also towards sintering. The common sand types based on silicon oxide clearly showed the worst results. 12 refs, 5 figs, 1 tab 12 refs, 5 figs, 1 tab

  7. The Effects of Agglomeration on the Formation and Scale of Operation of New Firms

    OpenAIRE

    Maryiam Haroon

    2013-01-01

    The formation of new firms is an important determinant of economic and regional development. The literature on industrial organization highlights agglomeration as one of the main factors enhancing the formation and scale of operation of new firms. Using data from the Directory of Industries, this study estimates a model that determines the effect of local conditions on new firms’ formation and scale of operation in the manufacturing sector in Punjab, Pakistan. Our findings reveal that agglome...

  8. Assessment of surface urban heat island across China's three main urban agglomerations

    Science.gov (United States)

    Liu, Yonghong; Fang, Xiaoyi; Xu, Yongming; Zhang, Shuo; Luan, Qingzu

    2017-06-01

    This article proposes a method for estimating the surface urban heat island intensity (SUHI) of urban areas, which addresses prior difficulties in the determination of rural contexts that may be used as a point of comparison. Based on indexes produced using this method, as well as remotely sensed datasets, the article compares the temporal and spatial characteristics of SUHIs within three major urban agglomerations (the Beijing-Tianjin-Hebei, the Yangtze River Delta, and the Pearl River Delta) and six typical metropolises. The article also examines the influence of socioeconomic factors on SUHI. The study revealed that this method is able to objectively monitor regional-scale SUHIs. The climate of the area studied is probably a determining factor in the seasonal variation of SUHIs. Research from the last 5 years (2010-2014) demonstrates that the urban heat island effect within the three urban agglomerations and five metropolises is serious. From 1994 to 2014, the average SUHI value for central urban areas rose from 0.4 to 2.3 K, while the total area where the SUHI value was >3.0 K increased from 1938 to 29,690 km2. The morphology of heat islands is significantly influenced by urbanization, meaning that heat islands within the areas studied will only continue to grow. Urban population and electricity consumption are the socioeconomic factors that exerted the greatest influence on the size of heat islands in China's major urban agglomerations. However, it is likely that economic measures designed to mitigate the UHI effect will differ in effectiveness from one urban agglomeration to another.

  9. Intangible resources, agglomeration effect of FDI intensity, and firm performance: Evidence from Chinese semiconductor firms

    OpenAIRE

    Qin Yang; Crystal X. Jiang; Sali Li

    2010-01-01

    This study analyzes the impact of intangible resources on firm performance in an emerging economy context. Intangible resources are considered essential to firms? competitive advantage; however, we argue that firms? intangible resources can be negatively related with performance in emerging economies, due to their weak intellectual property rights protection. Furthermore, we incorporate the resource-based view and geographical agglomeration perspective to propose that geographical locations w...

  10. Investigations on Agglomeration and Haemocompatibility of Vitamin E TPGS Surface Modified Berberine Chloride Nanoparticles

    Directory of Open Access Journals (Sweden)

    Parameswara Rao Vuddanda

    2014-01-01

    Full Text Available The objective of the present study is to investigate the influence of surface modification on systemic stability of NPs. Vitamin E TPGS (1% w/v was used for surface modification of berberine chloride nanoparticles. Naked and surface modified NPs were incubated in different SBFs (pH 6.8 and 7.4 with or without bile salts and human plasma. NPs were observed for particle agglomeration and morphology by particle size analyzer and TEM, respectively. The haemocompatibility studies were conducted on developed NPs to evaluate their safety profile. The surface modified NPs were stable compared to naked NPs in different SBFs due to the steric stabilization property of vitamin E TPGS. Particle agglomeration was not seen when NPs were incubated in SBF (pH 6.8 with bile salts. No agglomeration was observed in NPs after their incubation in plasma but particle size of the naked NPs increased due to adhesion of plasma proteins. The TEM images confirmed the particle size results. DSC and FT-IR studies confirmed the coexistence of TPGS in surface modified NPs. The permissible haemolysis, LDH release, and platelet aggregation revealed that NPs were compatible for systemic administration. Thus, the study illustrated that the surface modification is helpful in the maintenance of stability of NPs in systemic conditions.

  11. Experimental and numerical study on the optical properties and agglomeration of nanoparticle suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Otanicar, Todd, E-mail: todd-otanicar@utulsa.edu; Hoyt, Jordan; Fahar, Maryam [University of Tulsa, Department of Mechanical Engineering (United States); Jiang, Xuchuan [University of New South Wales, School of Materials Science and Engineering (Australia); Taylor, Robert A. [University of New South Wales, School of Mechanical and Manufacturing Engineering (Australia)

    2013-11-15

    Nanoparticles have garnered significant interest because of their ability to enhance greatly the optical properties of the base fluid in which they are suspended. The optical properties of nanoparticles are sensitive to the materials used, as well as to the host medium. Most fluids exhibit refractive indices that are highly temperature-dependent, resulting in nanoparticle suspensions which also exhibit temperature-dependent optical properties. Previous work has shown that temperature increases result in decreased absorption in nanoparticle suspensions. Here, we expand previous work to include core–shell particles due to the potential spectral shifts in optical properties that will arise from the base fluid with temperature changes and the role of agglomeration under temperature cycling through both experimental and numerical efforts. Thermal cycling tests for silica and gold, the constituents of the core–shell nanoparticles used in this study, were tested to determine the extent of particle agglomeration resulting from up to 200 accelerated heating cycles. Optical properties were recorded after heating two base fluids (water and ethylene glycol) with multiple surfactants for silver nanospheres and silica–gold core–shell nanoparticles. It was found that the temperature results in a small increase in the transmittance for both particle types and a blue shift in the spectral transmittance for core–shell nanoparticles. Further, the coupling effect of temperature and agglomeration played a significant role in determining both the spectral properties—particularly the resulting transmittance—of the silver nanoparticle suspensions.

  12. Control of nanoparticle agglomeration through variation of the time-temperature profile in chemical vapor synthesis

    Science.gov (United States)

    Djenadic, Ruzica; Winterer, Markus

    2017-02-01

    The influence of the time-temperature history on the characteristics of nanoparticles such as size, degree of agglomeration, or crystallinity is investigated for chemical vapor synthesis (CVS). A simple reaction-coagulation-sintering model is used to describe the CVS process, and the results of the model are compared to experimental data. Nanocrystalline titania is used as model material. Titania nanoparticles are generated from titanium-tetraisopropoxide (TTIP) in a hot-wall reactor. Pure anatase particles and mixtures of anatase, rutile (up to 11 vol.%), and brookite (up to 29 vol.%) with primary particle sizes from 1.7 nm to 10.5 nm and agglomerate particle sizes from 24.3 nm to 55.6 nm are formed depending on the particle time-temperature history. An inductively heated furnace with variable inductor geometry is used as a novel system to control the time-temperature profile in the reactor externally covering a large wall temperature range from 873 K to 2023 K. An appropriate choice of inductor geometry, i.e. time-temperature profile, can significantly reduce the degree of agglomeration. Other particle characteristics such as crystallinity are also substantially influenced by the time-temperature profile.

  13. Integrated low emission cleanup system for direct coal-fueled turbines (electrostatic agglomeration)

    Energy Technology Data Exchange (ETDEWEB)

    Quimby, J.M.; Kumar, K.S.

    1992-01-01

    The objective of this contract was to investigate the removal of SO[sub x] and particulate matter from direct coal fired combustion gas streams at high temperature and high pressure conditions. This investigation was to be accomplished through a bench scale testing and evaluation program for SO[sub x] removal and the innovative particulate collection concept of particulate growth through electrostatic agglomeration followed by high efficiency mechanical collection. The process goal was to achieve control better than that required by 1979 New Source Performance Standards. During Phase I, the designs of the combustor and gas cleanup apparatus were successfully completed. Hot gas cleanup was designed to be accomplished at temperature levels between 1800[degrees] and 2500[degrees]F at pressures up to 15 atmospheres. The combustor gas flow rate could be varied between 0.2--0.5 pounds per second. The electrostatic agglomerator residence time could be varied between 0.25 to 3 seconds. In Phase II, all components were fabricated, and erected successfully. Test data from shakedown testing was obtained. Unpredictable difficulties in pilot plant erection and shakedown consumed more budget resources than was estimated and as a consequence DOE, METC, decided ft was best to complete the contract at the end of Phase II. Parameters studied in shakedown testing revealed that high-temperature high pressure electrostatics offers an alternative to barrier filtration in hot gas cleanup but more research is needed in successful system integration between the combustor and electrostatic agglomerator.

  14. A Rational Analysis of Uniformity Risk for Agglomerated Drug Substance Using NIR Chemical Imaging.

    Science.gov (United States)

    Scherholz, Megerle L; Wan, Boyong; McGeorge, Gary

    2017-02-01

    Early risk detection and quick diagnosis of manufacturing challenges are necessary to support the accelerated development pace of drug product in the current competitive environment. Analytical tools, such as near-infrared (NIR) chemical imaging (CI), can be employed for alerting drug substance uniformity risks in intermediates and the final product of solid dosage forms. In this particular study, the ability to characterize the behavior of agglomerated drug substance throughout process development was enabled by NIR CI to identify uniformity risks with small sample sizes and short turnaround time. Using NIR chemical imaging, the drug substance distribution and cluster size in all intermediates were visualized throughout the drug product process. NIR CI enabled rapid identification of the key unit operations that produced the greatest reduction in cluster size for enhanced distribution of the drug substance. The comil acted as a high shear mixing step to disperse soft lumps prior to roller compaction. Shear forces or pressure during roller compaction was sufficient to break down and disperse the agglomerates further. Ultimately, the process was robust against a range of drug substance input properties such that the uniformity of the final blend was consistently achieved and the agglomerated drug substance had no risks to the drug product process.

  15. Control of nanoparticle agglomeration through variation of the time-temperature profile in chemical vapor synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Djenadic, Ruzica; Winterer, Markus, E-mail: markus.winterer@uni-due.de [Universität Duisburg-Essen, Nanoparticle Process Technology, Faculty of Engineering and CENIDE (Germany)

    2017-02-15

    The influence of the time-temperature history on the characteristics of nanoparticles such as size, degree of agglomeration, or crystallinity is investigated for chemical vapor synthesis (CVS). A simple reaction-coagulation-sintering model is used to describe the CVS process, and the results of the model are compared to experimental data. Nanocrystalline titania is used as model material. Titania nanoparticles are generated from titanium-tetraisopropoxide (TTIP) in a hot-wall reactor. Pure anatase particles and mixtures of anatase, rutile (up to 11 vol.%), and brookite (up to 29 vol.%) with primary particle sizes from 1.7 nm to 10.5 nm and agglomerate particle sizes from 24.3 nm to 55.6 nm are formed depending on the particle time-temperature history. An inductively heated furnace with variable inductor geometry is used as a novel system to control the time-temperature profile in the reactor externally covering a large wall temperature range from 873 K to 2023 K. An appropriate choice of inductor geometry, i.e. time-temperature profile, can significantly reduce the degree of agglomeration. Other particle characteristics such as crystallinity are also substantially influenced by the time-temperature profile.

  16. Visualizing powder de-agglomeration upon impact with simultaneous flowing charge behaviour

    Science.gov (United States)

    Kwek, Jin Wang; Heng, Desmond; Lee, Sie Huey; Ng, Wai Kiong; Chan, Hak-Kim; Heng, Jerry; Tan, Reginald

    2013-06-01

    The effectiveness of the dry powder inhaler (DPI) in treating respiratory diseases lies in its ability to deliver consistent and reliable drug dosage with each actuation. From aerosolization upon actuation to throat impaction, the deagglomeration with subsequent detachment of the drug from the carrier particles depend on the interaction forces, including electrostatic contributions, between the particles themselves or with the inhaler wall and the extent of which could depend on the surface roughness of the carrier particles. In this study, we have simultaneously investigated the contributions of the electrostatic forces while visualizing the de-agglomeration and impaction behaviours of carrier powders in an impaction throat model using a non-contact vibrating capacitive probe and a high speed camera respectively. Rough and smooth carrier particles were obtained by spray drying and then aerosolized at 60 L/min in the model. Higher flowing charges were observed for the rough aerosolized carrier particles while experiencing rebound or limited agglomerate fracture upon impaction. On the other hand, smooth particles were broken up upon impaction resulting in a 'plume-like' re-entrainment. Further analyses revealed that the increased moisture sorption on the larger specific surface area of the rough particles would have facilitated the accumulation of surface charges that could in turn contribute to the cohesiveness of the rough particles. Combined high speed imaging with electrostatic monitoring has proved to be useful in investigating the mechanisms of powder de-agglomeration upon impaction.

  17. Assessment of Urban Ecosystem Health Based on Entropy Weight Extension Decision Model in Urban Agglomeration

    Directory of Open Access Journals (Sweden)

    Qian Yang

    2016-08-01

    Full Text Available Urban ecosystem health evaluation can assist in sustainable ecological management at a regional level. This study examined urban agglomeration ecosystem health in the middle reaches of the Yangtze River with entropy weight and extension theories. The model overcomes information omissions and subjectivity problems in the evaluation process of urban ecosystem health. Results showed that human capital and education, economic development level as well as urban infrastructure have a significant effect on the health states of urban agglomerations. The health status of the urban agglomeration’s ecosystem was not optimistic in 2013. The majority of the cities were unhealthy or verging on unhealthy, accounting for 64.52% of the total number of cities in the urban agglomeration. The regional differences of the 31 cities’ ecosystem health are significant. The cause originated from an imbalance in economic development and the policy guidance of city development. It is necessary to speed up the integration process to promote coordinated regional development. The present study will aid us in understanding and advancing the health situation of the urban ecosystem in the middle reaches of the Yangtze River and will provide an efficient urban ecosystem health evaluation method that can be used in other areas.

  18. Agglomeration of urinary nanocrystallites: Key factor to formation of urinary stones

    Energy Technology Data Exchange (ETDEWEB)

    He Jieyu [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Ouyang Jianming, E-mail: toyjm@jnu.edu.cn [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Yang Rue [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China)

    2010-07-20

    With transmission electron microscopy (TEM) and nanoparticle size analyzer, comparative studies were conducted on the property variation of nanocrystallites in the urine of 5 lithogenic patients and 5 healthy subjects following the placement time (t{sub 1}). These properties include average particle size (d), size distribution, intensity-autocorrelation function, Zeta potential ({zeta}) and aggregation state. With the prolongation of t{sub 1} from 0 h to 4 h, d value of the nanocrystallites in urine of lithogenic patients increased from 742 nm to 1667 nm, the autocorrelation time increased from 7.68 ms to 1050 ms and {zeta} decreased from -1.52 mV to -4.44 mV, respectively; the autocorrelation curves were of fluctuating and unsmooth, and TEM showed that most of the patient's urinary nanocrystallites were in aggregation state and three types of agglomeration were observed. However, for nanocrystallites in urine of healthy subjects, there was little variation in the above properties within 4 h. The autocorrelation curves were of regular and smooth, and TEM showed that healthy urinary nanocrystallites were well-dispersed. The above results show that the nanocrystallites in urine of healthy subjects can keep stability, whereas those of lithogenic patients are easier to agglomerate gradually; and the agglomeration of urinary nanocrystallites is the key factor to stone formation.

  19. Predicting the Agglomeration of Cohesive Particles in a Gas-Solid Flow and its Effect on the Solids Flow

    Science.gov (United States)

    Kellogg, Kevin; Liu, Peiyuan; Lamarche, Casey; Hrenya, Christine

    2017-11-01

    In flows of cohesive particles, agglomerates will readily form and break. These agglomerates are expected to complicate how particles interact with the surrounding fluid in multiphase flows, and consequently how the solids flow. In this work, a dilute flow of particles driven by gas against gravity is studied. A continuum framework, composed of a population balance to predict the formation of agglomerates, and kinetic-theory-based balances, is used to predict the flow of particles. The closures utilized for the birth and death rates due to aggregation and breakage in the population balance take into account how the impact velocity (the granular temperature) affects the outcome of a collision as aggregation, rebound, or breakage. The agglomerate size distribution and solids velocity predicted by the continuum framework are compared to discrete element method (DEM) simulations, as well to experimental results of particles being entrained from the riser of a fluidized bed. Dow Corning Corporation.

  20. Effect of a Dispersant Agent in Fine Coal Recovery from Washery Tailings by Oil Agglomeration (Preliminary Study)

    Science.gov (United States)

    Yasar, Özüm; Uslu, Tuncay

    2017-12-01

    Among the fine coal cleaning methods, the oil agglomeration process has important advantages such as high process recovery, more clean product, simple dewatering stage. Several coal agglomeration studies have been undertaken recently and effects of different variables on the process performance have been investigated. However, unlike flotation studies, most of the previous agglomeration studies have not used dispersing agents to minimize slime coating effects of clays. In this study, agglomeration process was applied for recovery of fine coals from coal washery tailings containing remarkable amount of fine coal. Negative effect of fine clays during recovery was tried to be eliminated by using dispersing agent instead of de-sliming. Although ash reductions over 90 % were achieved, performance remained below expectations in terms of combustible matter recovery. However, this study is a preliminary one. It is considered that more satisfied results will be obtained in the next studies by changing the variables such as solid ratio, oil dosage, dispersant type and dosage.

  1. Concentrations en métaux toxiques chez Crassostrea gasar (Huître de mangrove) en zone urbaine lagunaire d'Abidjan (Côte d'Ivoire)

    OpenAIRE

    Métongo, Bernard Soro

    1991-01-01

    Cet article présente les résultats relatifs à une étude des concentrations en métaux toxiques (Cd, Cu, Hg et Zn) chez Crassostrea gasar (huître de mangrove). Une étude comparative est faite entre les échantillons collectés en zone urbaine (Abidjan) et ceux des régions rurales (Assini-mafia et Assouindé). Les échantillons collectés en zone urbaine d'Abidjan ont des teneurs en métal plus élevées que ceux de la zone rurale, en raison de la pollution chimique due aux rejets urbains et industriels...

  2. Formes de la croissance urbaine et exclusion sociale à la Réunion: un héritage historique

    Directory of Open Access Journals (Sweden)

    Cécile Martignac

    2011-08-01

    Full Text Available Cet article propose de mieux comprendre les mécanismes de la croissance urbaine à la Réunion en s’appuyant sur une démarche de modélisation qui mobilise la notion de champs géographiques. Le modèle géographique MUTE (Modèle d’Urbanisation du TErritoire calcule une propension à l’urbanisation du territoire. L’évaluation du modèle met en évidence l’existence, à côté d’une forme d’urbanisation classique, d’un autre modèle d’urbanisation. Ce dernier qualifié de post-agricole permet une interprétation différente des mécanismes de périurbanisation rapide des Hauts de l’île. Loin d’être la résultante d’un dysfonctionnement territorial, il apparaît davantage comme la conséquence d’un héritage historique et de choix politiques réalisés depuis longtemps en faveur d’un modèle de développement agricole postcolonial basé sur l’exclusion sociale.

  3. Les pollutions atmosphériques urbaines de proximité à l’heure du Développement Durable

    Directory of Open Access Journals (Sweden)

    Aymeric Blanchet

    2005-06-01

    Full Text Available Les pollutions atmosphériques de proximité liées au tissu urbain dense sont l’objet de nuisances ressenties et dénoncées par les citadins. Historiquement, l’histoire des odeurs délétères en ville est associée aux activités industrielles. Or les politiques municipales, très attentives au moment de l’hygiènisme à l’encadrement des pollutions industrielles, se sont détournées de la question de la pollution atmosphérique urbaine confiée, pour être mesurée et surveillée, à des réseaux de surveillance. La mesure de ces pollutions invisibles et nocives est restée largement cantonnée dans la sphère technique jusqu’à ces dernières années où, progressivement, la pollution atmosphérique est devenue un objet politique. Malgré la récurrence dans le temps du phénomène de pollution urbaine de proximité, et l’importance croissante des plaintes des habitants que cela génère, les réponses institutionnelles n’ont pas encore été complètement formalisées jusqu’à présent pour définir un mode de traitement et des réponses à apporter. Un suivi des plaintes, réalisé à Paris et dans la région Nord-Pas-de-Calais, sur le territoire de l’Artois, le montre bien. La prise en compte et le traitement des nuisances dues aux pollutions urbaines de proximité sont encore difficiles et nécessitent du temps pour être reconnues, comme le montre l’exemple de la commune de Drocourt. En outre, ces nuisances sont encore difficilement évaluables et quantifiables et les réponses qui s’esquissent répondent peu au principe de Développement Durable et s’appuient davantage sur une logique de remédiation, bien plus que de précaution. La question des nuisances environnementales et les plaintes qu’elles génèrent ont un caractère ambigu : entre santé et qualité de vie, entre industrie et urbanité, entre nuisance et toxicité, entre gêne et pollution de proximité. Leur ambiguïté permet d’interroger la

  4. Le rôle des politiques publiques dans l’éclatement urbain : l’exemple de la Belgique

    Directory of Open Access Journals (Sweden)

    Olivier Dubois

    2005-06-01

    Full Text Available Le présent article se veut une synthèse des différents facteurs qui expliquent le caractère particulièrement éclaté de l’urbanisation en Belgique. Cette revue permet de souligner que les dynamiques urbaines actuellement observables résultent de la conjonction de différents facteurs, parfois issus de décisions très anciennes. La place centrale que jouent les pouvoirs publics, notamment au travers de l’aide à l’accès à la propriété, est relevée. Ceci permet de tracer quelques pistes générales pour la promotion d’une urbanisation future plus respectueuse des principes généraux du développement durable.This article tries to synthesize the main factors that explain the extent of urban sprawl in Belgium. This review emphasizes that the present dynamics results from different factors, some of which are ancient. The central place of the public authorities is highlighted, in particular by the way of measures favorable to private ownership. This ancient and central role allows us to draw some guidelines for promoting a new urbanization more in line with the principles of sustainable development.

  5. Application of nanoparticle tracking analysis platform for the measurement of soot-in-oil agglomerates from automotive engines

    OpenAIRE

    La Rocca, A.; Di Liberto, G.; Shayler, P.J.; Parmenter, C.D.J.; Fay, M.W.

    2014-01-01

    Nanoparticle Tracking Analysis (NTA) has been applied to characterising soot agglomerates of particles and compared with Transmission Electron Microscoscopy (TEM). Soot nanoparticles were extracted from used oil drawn from the sump of a light duty automotive diesel engine. The samples were prepared for analysis by diluting with heptane. Individual tracking of soot agglomerates allows for size distribution analysis. The size of soot was compared with length measurements of projected two-dimens...

  6. Enhanced dissolution rate of felodipine using spherical agglomeration with Inutec SP1 by quasi emulsion solvent diffusion method

    Science.gov (United States)

    Tapas, A.R.; Kawtikwar, P.S.; Sakarkar, D.M.

    2009-01-01

    Felodipine is a second generation calcium channel blocker widely used as antihypertensive and antianginal drug which belongs to BCS class II category. Hence, its low water solubility limits the pharmacological effect. The aim of this study was to improve the dissolution rate of felodipine using spherical agglomeration technique with acetone, water and dichloromethane as good solvent, poor solvent and bridging liquid, respectively. The quasi emulsion solvent diffusion technique was used as a method for spherical agglomeration. Inutec SP1 was used as an emulsion stabilizer and as hydrophilic polymer in agglomeration process. The FTIR and DSC results showed no change in the drug after crystallization process. PXRD studies showed sharp peaks in the diffractograms of spherical agglomerates with minor reduction in height of the peaks. The particle size of spherical agglomerates (FI-2) was about 134.33 ± 13.57 µm, n=3 and the dissolution efficiency of felodipine up to 120 min increased to about 4-fold in phosphate buffer containing 1.8% Tween 80 (pH 6.8). Spherical agglomerates showed enhanced solubility compared to untreated powder possibly due to the partial conversion to amorphous form. PMID:21589802

  7. Experiment Investigation of the Influencing Factors on Bed Agglomeration During Fluidized-Bed Gasification of Biomass Fuels

    Science.gov (United States)

    Chen, Y. Q.; Chen, H. P.; Yang, H. P.; Wang, X. H.; Zhang, S. H.

    With the depleting of fossil fuel and environmental polluting increasing, the utilization of biomass resources caught increasing concern. Biomass gasification in fluidized bed, as one promising technology, developed quickly. However, serious agglomeration was displayed as biomass ash reacted with bed material (silica sand) at higher temperature. It hindered the wide utilization of CFB gasifier. The objective ofthis work is to investigate the agglomeration behavior between biomass ash and silica sand, and catch the inherent mechanism. Firstly, the influence of ash compounds on the agglomeration behavior was analyzed with biomass ash and synthesis ash compounds addition in fixed bed as ash sample mixed with bed material evenly before every trial. The reaction temperature was set 850°C that is the operated temperature for many fluidized bed gasificated biomass fuels. Then the influence of reaction time was analyzed. The characteristics of the agglomerated silica sand particles were analyzed by the XRD. Finally, it was simulated with HSC computer mode based on thermodynamic equilibrium. It was observed that when the ratio of the biomass ash to the silica sand was above 0.2, the agglomeration was observed. With the increase of the reaction time, more silica sand particles agglomerated with the biomass ash. There are two kinds of silicate eutecticum investigated by the XRD. It is of great significance for the running ofCFB biomass gasifier and the development ofbiomass utilization technology.

  8. Le mouvement du New Urbanism et le paysage urbain. La circulation d’une doctrine urbanistique The New Urbanism movement and the urban landscape: the circulation of a town-planning doctrine

    Directory of Open Access Journals (Sweden)

    Blaise Dupuis

    2009-10-01

    Full Text Available Institué en 1993, le mouvement américain du New Urbanism prescrit à une échelle internationale un mode spécifique de connaissance et d’action sur l’espace urbain : le modèle néo-traditionnel (Traditional Neighborhood Development – TND. Celui-ci postule un lien organique entre formes urbaines et relations sociales, ce lien pouvant en particulier être compris à travers la notion de paysage urbain. Partant de la distinction entre paysage de ville et paysages de l’urbain, cet article propose de comprendre comment la notion de paysage urbain est définie et partagée par les acteurs du TND dans un contexte de mondialisation, de circulation et de concurrence des modèles urbains. D’après l’exemple du townscape et du New Urbanism, l’article expose comment des standards circulent, sont légitimés à travers des institutions ou des projets urbains tels que celui de l’agence DPZ à Berlin. En conclusion, il est montré que les acteurs du TND, bien que bénéficiant d’un faible capital symbolique au sein du champ professionnel de l’architecture, ont néanmoins réussi à constituer un réseau international promouvant une morphologie urbaine normative et historiciste.The American-based movement of the New Urbanism was founded in 1993. It prescribes a specific mode of knowledge and action on the urban space at an international scale: the neo-traditional model, also called Traditional Neighborhood Development (TND. This model postulates an organic link between urban forms and social relations and this link can be understood in particular through the notion of urban landscape. Following the distinction between townscape and streetscapes, this article aims to understand how the notion of urban landscape is defined and shared by the actors of the TND in a context of globalization, circulation and competition of urban models. Through the example of the townscape and the New Urbanism, the article outlines how standards circulate and

  9. Achille Urbain (1884-1957), de la gloire à l'oubli : un vétérinaire pasteurien au Muséum national d'Histoire naturelle

    OpenAIRE

    Borrel, Thierry

    2014-01-01

    From a humble background, Achille Joseph Urbain (1884-1957) became a military veterinarian in 1906. He submitted his botany dissertation in 1920, and then worked in Besredka’s laboratory at the Pasteur Institute of Paris. In 1931, Urbain joined the National Museum of Natural History of Paris, in which, he became the first holder of the chair of “ Ethology of wild animals ” in 1934. Cofounder of the zoological park of Vincennes and concerned with protection of nature in the national and intern...

  10. L’interaction urbain-rural : une problématique renouvelée Urban-rural interaction revisited

    Directory of Open Access Journals (Sweden)

    Christian Vandermotten

    2010-12-01

    Full Text Available La distinction entre l’urbain et le rural était claire sous l’Ancien Régime, dans des sociétés peu mobiles. La révolution industrielle accentue l’identification entre la ville, l’industrie et la modernité. Après la Seconde Guerre mondiale, le développement du transport routier affranchit l’industrie des localisations urbaines et la périurbanisation progresse. En même temps, l’accroissement des productivités agricoles libère de plus en plus de main-d’œuvre paysanne. Après deux siècles au moins d’exode rural, les campagnes se rurbanisent, mais cette rurbanisation s’inscrit dans un contexte global de mégapolisation. Cette configuration devrait imposer une nouvelle appréciation des rapports entre l’urbain et le rural, en ce compris leurs rapports politiques.The distinction between urban and rural was clear under the Ancien Régime, as societies featured a low level of mobility. The industrial revolution increased the identification between cities, manufacturing and modernity. After the Second World War, growing road traffic freed industries from urban locations and suburbanisation thus increased. Simultaneously, the increase in food productivity required fewer and fewer agricultural workers. After more than two centuries of rural exodus, rurbanisation transformed rural areas, even as this very process of rurbanisation should be seen as part of a global megapolization process. This pattern implies new kinds of relations between the rural and the urban, including from a political point of view.

  11. Les temporalités frontalières et urbaines du port de Strasbourg. Analyse géohistorique d’une relation fluviale ville-port

    Directory of Open Access Journals (Sweden)

    Antoine Beyer

    2012-05-01

    Full Text Available L’éclairage géohistorique de la relation ville-port à Strasbourg implique un croisement de deux chronologies, l’une géopolitique, liée à une position frontalière évolutive, l’autre économique et générale, articulée à l’histoire portuaire dans une perspective plus résolument urbaine de la déconnexion-reconnexion des deux espaces fonctionnels. Dans cette logique, l’analyse suivie envisagera alternativement l’évolution de la fonction portuaire de Strasbourg dans une situation d’instabilité frontalière, pour considérer ensuite la manière dont l’espace portuaire participe au projet urbain. Ces deux approches permettront par ailleurs d’envisager l’analyse à deux échelles géographiques, celle de l’espace régional et celle de l’aménagement urbain.The geo-historical approach to the relation port-city in the case of Strasbourg (France implies to consider at the same time two chronologies. On the one hand, the geopolitical dimension with a city leaned on the french-german border. On the other hand, the more common economic development with the connection and the de-connection phases of the two functional spaces involved, i.e. port and urban spaces. In such a perspective, the paper will develop alternatively the way the port grew in a political unstable context, and replace its developement in the shaping of the global urbanization. Those two topics will in return differenciate two geographical scales, the regional environment and the more local urban planning strategies.

  12. Città, violenza urbana e sentimento di insicurezza / Villes, violence urbaine et sentiment d’insécurité / Cities, urban violence and insecurity

    Directory of Open Access Journals (Sweden)

    Lourenço Nelson

    2012-10-01

    Full Text Available Cet article met en évidence que la violence urbaine et l’insécurité sont des thèmes centraux pour les sociétés actuelles car ils font partie des préoccupations de la population et de la vie démocratique de manière significative. Pour aborder cette problématique, il est nécessaire d’effectuer une analyse extensive de la mondialisation et des dynamiques urbaines qui caractérisent la fin de l’époque moderne dans ses multiples dimensions, par exemple sociales, culturelles et politiques. Violence urbaine et insécurité demandent une structure institutionnelle nouvelle et la définition de politiques publiques de sécurité nouvelles pour répondre à l’insécurité qui domine dans les sociétés urbaines.L’analyse globale des relations entre l’évolution de la criminalité et le développement du sentiment d’insécurité amène l’auteur à expliquer la manière dont les sociétés contemporaines vivent et abordent la question de la sécurité. This paper argues that urban violence and insecurity are central societal issues which are a significant part of people's concerns and democratic life. Its analysis implies an extensive understanding of globalisation and urban dynamics that characterise late modernity in its multiple dimensions: i.e. the social, cultural, political, and economical dimensions.Urban violence and insecurity call for a new institutional framework and the definition of new public security policies that will respond to the insecurity that prevails in urban society.The comprehensive analysis of the relationship between the evolution of crime and the development of the feeling of insecurity allows us to understand how contemporary society lives and deals with the issue of security.

  13. La permaculture au sein de l’agriculture urbaine : Du jardin au projet de société

    OpenAIRE

    Pezrès, Emmanuel

    2010-01-01

    La permaculture est souvent considérée comme un procédé « alternatif » de production alimentaire écologique en ville ou à la campagne. Cependant, et bien que la définition et les principes de la permaculture soient en constante évolution, il apparaît que la permaculture n'est pas simplement une autre façon de jardiner, mais une autre façon de concevoir le monde. Considérant la place de la permaculture dans le processus de l'agriculture urbaine, nous remarquons que la conception permaculturell...

  14. Renforcer les compétences grâce à l’agriculture urbaine : rapport sur le projet Askîy

    OpenAIRE

    Wanda Martin; Lindsey Vold

    2018-01-01

    Introduction : De nombreuses villes d’Amérique du Nord ont construit un environnement donnant accès à des aliments riches en calories et laissant peu de possibilités de mener une vie active. L’agriculture urbaine contribue à un environnement favorable grâce à la culture de végétaux destinés à l’alimentation, ce qui implique leur transformation, leur entreposage, leur distribution et leur compostage. Elle constitue un moyen d’augmenter la production alimentaire locale et d’améliorer ainsi la s...

  15. D'Eichthal and Urbain's "Lettres sur la race noire et la race blanche": race, gender, and reconciliation after slave emancipation.

    Science.gov (United States)

    Andrews, Naomi J

    2011-01-01

    This article is a close reading of Gustave D'Eichthal and Ishmayl Urbain's Lettres sur la race noire et la race blanche (1839), written during the decade prior to the "second" French emancipation in 1848. The article argues that the hierarchical gendering of race described in the letters is reflective of metropolitan concerns about potential for social disorder accompanying slave emancipation in the French colonies. In arguing for social reconciliation through interracial marriage and its offspring, the symbolically charged figure of the mulatto, the authors deployed gendered and familial language to describe a stable post-emancipation society.

  16. La centralité des médinas maghrébines : quel enjeu pour les politiques d’aménagement urbain ?

    OpenAIRE

    Signoles, Pierre

    2013-01-01

    La centralité des médinas est prise ici comme prétexte pour interroger les relations entre recherche, pratique, planification et gestion urbaines dans quelques pays du Monde arabe. La question se pose en effet, avec d’autant plus d’acuité que deux processus concomitants conjuguent depuis quelques décennies leurs effets pour donner à croire que la problématique de la centralité de ces médinas ne serait plus d’actualité. D’une part, les politiques dites de sauvegarde tendent, à quelques excepti...

  17. Temporal Agglomeration

    OpenAIRE

    Robert E. Hall

    1989-01-01

    When economic activity is concentrated over space or over time, it is more efficient. Most production occurs in geographic hot spots, and most production occurs between 9 and 12 in the morning and 1 to 5 in the afternoon on weekdays. The thick-market efficiencies that encourage the concentration of activity in certain time periods may be internal to the firm, or they may be external to the firm. When they are internal, the firm can make efficient arrangements to take advantage of the effects....

  18. Dust agglomeration

    Science.gov (United States)

    2000-01-01

    John Marshall, an investigator at Ames Research Center and a principal investigator in the microgravity fluid physics program, is studying the adhesion and cohesion of particles in order to shed light on how granular systems behave. These systems include everything from giant dust clouds that form planets to tiny compressed pellets, such as the ones you swallow as tablets. This knowledge should help us control the grains, dust, and powders that we encounter or use on a daily basis. Marshall investigated electrostatic charge in microgravity on the first and second U.S. Microgravity Laboratory shuttle missions to see how grains aggregate, or stick together. With gravity's effects eliminated on orbit, Marshall found that the grains of sand that behaved ever so freely on Earth now behaved like flour. They would just glom together in clumps and were quite difficult to disperse. That led to an understanding of the prevalence of the electrostatic forces. The granules wanted to aggregate as little chains, like little hairs, and stack end to end. Some of the chains had 20 or 30 grains. This phenomenon indicated that another force, what Marshall believes to be an electrostatic dipole, was at work.(The diagram on the right emphasizes the aggregating particles in the photo on the left, taken during the USML-2 mission in 1995.)

  19. Impact of the daily variations of the air pollution on the ambulatory emergency health services activity. Study in the urban area of Rouen (France); Impact des variations quotidiennes de la pollution atmospherique sur l'activite du dispositif d'urgences pre-hospitalieres. Etude dans l'agglomeration de Rouen

    Energy Technology Data Exchange (ETDEWEB)

    Hautemaniere, A.; Czernichow, P.; Germain, J.M.; Zeghnoun, K. [Centre Hospitalier Universitaire, Dept. d' Epidemiologie et de Sante Publique, 76 - Rouen (France); Delmas, V. [Air Normand, 76 - Rouen (France); Falourd, J.C.; Dureuil, B. [Service d' Aide Medicale Urgente de Seine Maritime, 76 - Rouen (France)

    2000-10-01

    The aim of this study was to evaluate feasibility of using both the emergency phone calls (SAMU) and medical interventions (SMUR) related to ambulatory emergency services for local epidemiological surveillance of health impact of air pollution. A temporal ecological study was performed at Rouen area (france) (380000 inhabitants) for 1990-1997 (SAMU) and 1990-1996 (SMUR). The pollutants tested were: Sulphur dioxide (SO{sub 2}), Particles (PM13), and Nitrogen dioxide (NO{sub 2}), as collected routinely by a local automated network. For each phone call (SAMU) or emergency interventions (SMUR), the date, medical reason for calling (SAMU) or diagnosis after interventions (SMUR) (classified as respiratory, cardiovascular or other diseases) have been extracted from a specific information system. A statistical analysis based on time series analysis associated to a Poisson regression was conducted, taking into account temporal trend, seasonal variations, influenza, days of the week, holiday and meteorological data. An association was observed between ambulatory emergency services activity for cardiovascular diseases, and the daily variations of both SO{sub 2} (relative risk = 1.008 [1.001-1.016] for SAMU with an increase of 10{mu}g/m{sup 3}) and NO{sub 2} (relative risk 1.018 [1.008-1.030] for SAMU, relative risk = 1.016 [1.001-1.032] for SMUR with an increase of 10{mu}g/m{sup 3}). No association could be observed with the respiratory diseases for these pollutants. The ambulatory emergency services activity data could contribute to an epidemiological surveillance of the health impact of the air pollution, but a better quality of data collected (concerning both procedures and codification) is requested. The interest of an epidemiological surveillance, rather than usual pollutant monitoring, remains to evaluate. (authors)

  20. Use of hydraulic and aerial mock up to study atmospheric pollution; L'utilisation des maquettes aeriennes et hydrauliques pour l'etude de la pollution atmospherique

    Energy Technology Data Exchange (ETDEWEB)

    Facy, L.; Perrin De Brichambaut, C.; Doury, A.; Le Quinio, R

    1962-07-01

    , et avec la collaboration de l'Institut Aerotechnique de Saint-Cyr. Les resultats obtenus sont essentiellement de deux natures: - le modele mathematique de diffusion turbulente dans l'atmosphere, deduit de la theorie de Sutton, et que nous utilisons generalement, s'est trouve correctement verifie, qualitativement et quantitativement, dans tous les cas ou les conditions de validite de la theorie etaient remplies par l'experience; - les essais qualitatifs de visualisations photographiques ou cinematographiques ont apporte des precisions interessantes sur des phenomenes pratiquement inaccessibles aux calculs, lies notamment a l'influence des obstacles et des conditions de rejet. D'une maniere generale, on peut affirmer que les etudes de pollution atmospherique peuvent etre menees a bien par des experimentations sur maquettes, et que dans certains cas ces experimentations ne pourront jamais etre remplacees par des modeles mathematiques purs. (auteurs)

  1. The effects of agglomeration/defluidization on emission of heavy metals for various fluidized parameters in fluidized-bed incineration

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chiou-Liang; Tsai, Ming-Chih; Chang, Chih-Hung [Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, 811 (China)

    2010-01-15

    The agglomeration/defluidization may be produced to generate the secondary pollutant during incineration. However, the effects of agglomeration/defluidization on heavy metal distribution have rarely been examined. Therefore, the effects of the agglomeration/defluidization process on heavy metal emission in flue gas are studied. The artificial waste is employed to simulate municipal waste and to form agglomerates, which contain alkali metals, earth alkali metals, a mixture of metals (Pb, Cr and Cd) and sawdust. The fluidized parameters (including gas velocity, sand particle size and static bed height) are varied to determine their influences on heavy metal emission. The results indicate that addition of Na increases the risk of agglomeration/defluidization, but the emission concentration of heavy metals decreases during agglomeration/defluidization. The heavy metals may react with Na to form the eutectics or are covered and adhered by the liquid-phase eutectics of Na to stay in sand particle and lead to a decrease in the emission of heavy metals. The system was operated at a low gas velocity that not only easily resulted in agglomeration/defluidization but also increased the emission concentration of heavy metals. Large particles (920 {mu}m), which have a poor fluidized quality, had the highest emission concentration. Small particles (645 {mu}m) were uniformly fluidized to enhance the fluidization quality and to decrease the emission concentration. Additionally, adding Ca did not decrease the heavy metal emission concentration, but maintained the fluidization during eutectic accumulation. The Ca prevented the sand bed from quickly achieving defluidization and prolonged the increased emission of heavy metals after defluidization. (author)

  2. A Comparative Study on Changes in the Spatial Industry Agglomeration in Eastern EU Developing Countries: Romania vs. Bulgaria

    Directory of Open Access Journals (Sweden)

    Madalina-Stefania Dirzu

    2013-08-01

    Full Text Available Taking a closer look at the spatial distribution of industrial sectors, it becomes quite obvious that there is an increasing disposition for industries to concentrate in certain regions in order to benefit of agglomeration assets. In this context, we consider necessary to analyze how industrial agglomerations have evolved over time and to what extent major transformations have affected agglomeration phenomenon in lagging regions of Eastern countries, finally our paper bringing supportive evidence from Romania and Bulgaria. To what extent, have patterns of industrial agglomeration modified during the transition period? Has relocation of economic activities taken place? What are the main determinants of industrial concentration patterns? These are some crucial questions that we try to find a realistic response through the present paper. Eastern economies are notably challenging from this point of view because they experienced several decades long economic development period which was earmarked by socialist industrialization. Under the planned economy, these countries have faced more barriers to an efficient geographical allocation of economic activities across regions than their peers in the Western Europe especially because they faced the legacy of a planned economy system that determined locations for economic activities based on political decisions, not based on economic efficiency. Thus, our effort can be seen as a contribution to knowledge about agglomeration in the non-Western countries in general, and in developing regions in particular. Focusing our study on two-digit industrial sectors of 14 regions at NUTS2 level, this paper aims to identify and explain the changes regarding the evolution of industrial agglomerations in the last years across Romania compared to Bulgaria. In the end, our analysis will be able to conclude in what manner the effects of transition period influenced the patterns of industrial agglomeration in these two

  3. Low temperature self-agglomeration of metallic Ag nanoparticles on silica sol-gel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akhavan, O; Azimirad, R; Moshfegh, A Z [Department of Physics, Sharif University of Technology, PO Box 11155-9161, Tehran (Iran, Islamic Republic of)], E-mail: oakhavan@sharif.edu

    2008-10-07

    A facile sol-gel synthesis for self-agglomeration of metallic silver nanoparticles, with fcc crystalline structure, on the silica surface in a low annealing temperature has been introduced. X-ray photoelectron spectroscopy (XPS) revealed initial agglomeration ({approx}30 times greater than the nominal concentration of Ag) of the nanoparticles on the surface of the dried film (100 deg. C) and also their oxidation as well as easy diffusion (with 0.08 eV required activation energy) into the porous silica thin films, by increasing the annealing temperature (200-400 deg. C). By raising the Ag concentration from 0.2 to 1.6 mol% in the sol, the average size of the Ag nanoparticles increased from {approx}5 to 37 nm corresponding to a redshift of the optical plasmon resonance absorption peak from 404 to 467 nm. The high concentration of Ag (1.6 mol%) in the sol resulted in a rough surface containing compact nanoparticles. Using power spectral density analysis of the atomic force microscopy images, we have found that the highest contributions in the surface roughness of the dried silica films were caused by the particles ranging from {approx}62 to 159 nm. The particles smaller than {approx}39 nm did not show any detectable contributions in the surface roughness of the dried silica film. Based on the XPS analysis, a mechanism has also been proposed for the self-agglomeration of the Ag nanoparticles on the surface of the aqueous sol-gel silica thin films.

  4. Diffusion mediated agglomeration of CdS nanoparticles via Langmuir–Blodgett technique

    Energy Technology Data Exchange (ETDEWEB)

    Das, Nayan Mani, E-mail: nayanmanidas3@gmail.com; Roy, Dhrubojyoti; Gupta, P.S.

    2013-10-15

    Graphical abstract: - Highlights: • Diffusion mediated agglomeration of CdS nanoparticles are discussed. • Formation of CdS nanoparticles are confirmed by the change of chain length in XRD. • AFM shows the agglomeration of particles with a film swelling of about 5 Å. • UV–vis absorbance suggests that the grown particles show quantum confinement. • Hexagonal form of particle was confirmed by UV–vis reflectivity. - Abstract: We have reported a diffusion mediated agglomeration of cadmium sulphide (CdS) nanoparticles within cadmium arachidate (CdA{sub 2}) film matrix. The structural morphology and formation of CdS nanoparticles are characterized by X-ray diffraction (XRD), X-ray reflectivity (XRR), atomic force microscopy (AFM) and ultraviolet-visible spectroscopy techniques. X-ray diffraction (XRD) results show a change in bilayer difference from 53.04 Å to 43 Å after the sulphidation. An epitaxial growth of the films by ∼5 Å after sulphidation is confirmed from atomic force microscopy studies. The particle size calculated form UV–vis absorption edges are found to be varying from 2.6 nm to 3.3 nm for the different layers. A lateral dimension of 72–80 nm from AFM measurements and a size of 2.6–3.3 nm have confirmed one side flat pseudo two-dimensional disk-like nanoparticles. UV–vis reflectivity peak at E{sub 1} (A) confirms the formation of hexagonal CdS nanoparticles along the c-axis.

  5. Stability of silver nanoparticles: agglomeration and oxidation in biological relevant conditions

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, Laura E.; Giacomelli, Carla E., E-mail: giacomel@fcq.unc.edu.ar [Universidad Nacional de Córdoba, Ciudad Universitaria, Instituto de Investigaciones en Físico Química de Córdoba (INFIQC) CONICET-UNC, Departamento de Fisicoquímica, Facultad de Ciencias Químicas (Argentina)

    2017-05-15

    Silver nanoparticles (Ag-NP) are the most used nanomaterial in consumer products due to the intrinsic antimicrobial capacity of silver. However, Ag-NP may be also harmful to algae, aquatic species, mammalian cells, and higher plants because both Ag{sup +} and nanoparticles are responsible of cell damages. The oxidative dissolution of Ag-NP would proceed to completion under oxic conditions, but the rate and extent of the dissolution depend on several factors. This work correlates the effect of the capping agent (albumin and citrate) with the stability of Ag-NP towards agglomeration in simulated body fluid (SBF) and oxidation in the presence of ROS species (H{sub 2}O{sub 2}). Capping provides colloidal stability only through electrostatic means, whereas albumin acts as bulky ligands giving steric and electrostatic repulsion, inhibiting the agglomeration in SBF. However, citrate capping protects Ag-NP from dissolution to a major extent than albumin does because of its reducing power. Moreover, citrate in solution minimizes the oxidation of albumin-coated Ag-NP even after long incubation times. H{sub 2}O{sub 2}-induced dissolution proceeds to completion with Ag-NP incubated in SBF, while incubation in citrate leads to an incomplete oxidation. In short, albumin is an excellent capping agent to minimize Ag-NP agglomeration whereas citrate provides a mild-reductive medium that prevents dissolution in biological relevant media as well as in the presence of ROS species. These results provide insight into how the surface properties and media composition affect the release of Ag{sup +} from Ag-NP, related to the cell toxicity and relevant to the storage and lifetime of silver-containing nanomaterials.

  6. Stability of silver nanoparticles: agglomeration and oxidation in biological relevant conditions

    Science.gov (United States)

    Valenti, Laura E.; Giacomelli, Carla E.

    2017-05-01

    Silver nanoparticles (Ag-NP) are the most used nanomaterial in consumer products due to the intrinsic antimicrobial capacity of silver. However, Ag-NP may be also harmful to algae, aquatic species, mammalian cells, and higher plants because both Ag+ and nanoparticles are responsible of cell damages. The oxidative dissolution of Ag-NP would proceed to completion under oxic conditions, but the rate and extent of the dissolution depend on several factors. This work correlates the effect of the capping agent (albumin and citrate) with the stability of Ag-NP towards agglomeration in simulated body fluid (SBF) and oxidation in the presence of ROS species (H2O2). Capping provides colloidal stability only through electrostatic means, whereas albumin acts as bulky ligands giving steric and electrostatic repulsion, inhibiting the agglomeration in SBF. However, citrate capping protects Ag-NP from dissolution to a major extent than albumin does because of its reducing power. Moreover, citrate in solution minimizes the oxidation of albumin-coated Ag-NP even after long incubation times. H2O2-induced dissolution proceeds to completion with Ag-NP incubated in SBF, while incubation in citrate leads to an incomplete oxidation. In short, albumin is an excellent capping agent to minimize Ag-NP agglomeration whereas citrate provides a mild-reductive medium that prevents dissolution in biological relevant media as well as in the presence of ROS species. These results provide insight into how the surface properties and media composition affect the release of Ag+ from Ag-NP, related to the cell toxicity and relevant to the storage and lifetime of silver-containing nanomaterials.

  7. Modern understanding of ‘geoeconomic position’ and the Saint Petersburg agglomeration

    Directory of Open Access Journals (Sweden)

    Kuznetsov S. V.

    2014-03-01

    Full Text Available This article presents a modern interpretation of the concept of ‘geoeconomic situation’ as applied to one of the most important centers of the Baltic region — the St. Petersburg agglomeration. The coastal location of the agglomeration and close connections with the Leningrad region make it possible to consider the Saint Petersburg coastal region (Baltic Area as a whole. The article sets out not only to verify, confirm, and explain the features of the geoeconomic position of the coastal region, but also to describe the contiguous geoeconomic space. The position of the St. Petersburg coastal region is of crucial importance for ensuring a steady growth of regional economy, the propagation of industrialization impulses, and modernization in the heart of Russian Northwestern macroregion. At the same time, the specific features of the region’s geoeconomic position magnify the ‘inherited’ ad acquired effects of focal industrialization and space polarization, which creates additional prerequisites for the inversion of the Russian economic space — ‘Russia of the physical space’ and ‘the economic space of Russia’. The study uses traditional methodology of economic geography (the territorial, cluster, and spatial approaches and the geoeconomic approach developed by the authors. The article also addresses recent findings in regional economy and spatial studies. It is aimed at the development of the geoeconomic paradigm in the framework of social geography and that of spatial science. An analysis of the geoeconomic position and the developing spatial relations can be of interest for researchers of geographic clusters, agglomerations, and such cross-border forms of cooperation, as growth triangles, for example.

  8. Study of agglomeration behavior of combustion-synthesized nano-crystalline ceria using new fuels

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Srirupa T.; Bedekar, Vinila [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Patra, A.; Sastry, P.U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India)], E-mail: aktyagi@barc.gov.in

    2008-10-20

    Ceria powders were prepared by gel combustion process using cerium nitrate and hitherto unexplored amino acid fuels such as aspartic acid, glutamic acid, arginine, tryptophan, phenyl alanine, valine, etc. These powders were characterized by X-ray diffraction, surface area analysis, sinterability, dynamic light scattering, scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS). The combustion-synthesized powders were agglomerates of nano-crystallites. SAXS profiles of the powders prepared using tryptophan, phenyl alanine and dimethyl urea exhibited fractal behavior.

  9. Urban expansion – Urban shrinking considerations on Braşov agglomeration urban dynamics

    Directory of Open Access Journals (Sweden)

    Cătălin Sârbu

    2012-05-01

    Full Text Available The study of the vision of spatial development at different scales can often suggest different solutions, due to the different priorities imposed by the distinct territorial governance levels. In this respect, it can be useful to point out the meanings of the terms like urban growth, urbanisation, urban expansion or urban sprawl and their relevance for the future of a defined human settlements system. The presentation of the case of Brasov city and its agglomeration emphasised some of the problems of urban dynamic.

  10. Influence of the nanoparticles agglomeration state in the quantum-confinement effects: Experimental evidences

    Directory of Open Access Journals (Sweden)

    I. Lorite

    2015-03-01

    Full Text Available The agglomeration state facilitates particle-particle interaction which produces important effects in the phonon confinement effects at the nanoscale. A partial phonon transmission between close nanoparticles yields a lower momentum conservation relaxation than in a single isolated nanoparticle. It means a larger red shift and broadening of the Raman modes than the expected ones for Raman quantum confinement effects. This particle-particle interaction can drive to error when Raman responses are used to estimate the size of the nanoscaled materials. In this work different corrections are suggested to overtake this source of error.

  11. Spatial Agglomeration, Human and Social Capital: The Case of Turkey Manufacturing Industry

    Directory of Open Access Journals (Sweden)

    Özer Karakayacı

    2017-12-01

    Full Text Available Over the last three decades, new economic theories explode the factors depending on space and spatial characteristics. In this process, it is developed the theories on social-cultural aspects and spatial characteristics of regions instead of traditional economic theories. These theories have been main strategy for economic development and growth. Economic development has not been considered independently from space by these theories and economic performance of a region was emphasized importance of economic actors, institutional and economic infrastructure as well as geographic features. Geography or spatial features contribute to increase not only skilled workforce, knowledge spillover and distribution but also social relations and interaction. In other words, the social-cultural and humanity factors relating with spatial and geography are major factors affecting on the development and also growing of economic activities. Especially, while industrialization as engine of regional development has been benefiting from the advantages offered by spatial features, clustering of economic activities and relationships among actors are shaped according to socio-cultural and human factors revealed spatial features. In this context, clustering of economic activities has been one of the new areas of interest in the theory of economic geography. Therefore, clustering of economic activities and human-social-spatial resources has been emphasized to play a major role in growth and development of regions by essays of the new economic geography. In that context, the aim of this paper is to determine the effects of human and social capital in the spatial agglomeration of economic activities in case of Konya-Turkey. In this study, the agglomeration tendencies for manufacturing industry in Konya, which have major potentials in terms of human and social capital and manufacturing industry potential, is analysed comparatively depending on secondary resources and using

  12. Cold Agglomeration of Ultrafine Oxidized Dust (UOD from Ferromanganese and Silicomanganese Industrial Process

    Directory of Open Access Journals (Sweden)

    María Ordiales

    2016-08-01

    Full Text Available Different wastes are generated in ferromanganese and silicomanganese alloy production. One of them is the ultrafine oxidized dust (UOD produced in the collection and control of flying dusts in the ferroalloy industry. This waste has fairly high manganese content (20%–40% Mn, making it suitable to be a secondary raw material for the ferromanganese industry. This research proposes a method for the transformation of UOD into a useable raw material. Cold agglomeration is the best option, due to its low energy consumption. Portland cement and refractory cement are compared as suitable candidates in the management of the UOD for their reuse in the electric arc furnace feed.

  13. Algae and their biodegradation effects on building materials in the Ostrava industrial agglomeration

    Science.gov (United States)

    Vojtková, H.

    2017-10-01

    Microorganisms cause changes in the building stone, which reduce its usable life and reliability. Microalgae make important parts of the biodegradation consortia of microorganisms on the surface of building materials. Via their metabolites, microalgae affect the stability of mineral components and thus lead to the material destruction. The aim of the paper was to identify aerophytic microalgae on the surface of engineering structures in the Ostrava agglomeration, and to describe the basic interactions between such microorganisms and the building materials, which may lead to the destruction of the materials.

  14. Influence of the nanoparticles agglomeration state in the quantum-confinement effects: Experimental evidences

    Energy Technology Data Exchange (ETDEWEB)

    Lorite, I., E-mail: lorite@physik.uni-leipzig.de [Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Kelsen 5, 28049, Madrid (Spain); Division of Superconductivity and Magnetism, Faculty of Physics and Earth Sciences, Linnestrasse 5, D-04103 Leipzig (Germany); Romero, J. J.; Fernandez, J. F. [Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Kelsen 5, 28049, Madrid (Spain)

    2015-03-15

    The agglomeration state facilitates particle-particle interaction which produces important effects in the phonon confinement effects at the nanoscale. A partial phonon transmission between close nanoparticles yields a lower momentum conservation relaxation than in a single isolated nanoparticle. It means a larger red shift and broadening of the Raman modes than the expected ones for Raman quantum confinement effects. This particle-particle interaction can drive to error when Raman responses are used to estimate the size of the nanoscaled materials. In this work different corrections are suggested to overtake this source of error.

  15. De-agglomeration Effect of the US Pharmacopeia and Alberta Throats on Carrier-Based Powders in Commercial Inhalation Products.

    Science.gov (United States)

    Leung, Sharon Shui Yee; Tang, Patricia; Zhou, Qi Tony; Tong, Zhenbo; Leung, Cassandra; Decharaksa, Janwit; Yang, Runyu; Chan, Hak-Kim

    2015-11-01

    The US pharmacopeia (USP) and Alberta throats were recently reported to cause further de-agglomeration of carrier-free powders emitted from some dry powder inhalers (DPIs). This study assessed if they have similar influences on commercially available carrier-based DPIs. A straight tube, a USP throat, and an Alberta throat (non-coated and coated) were used for cascade impaction testing. Aerosol fine particle fraction (FPF ≤ 5 μm) was computed to evaluate throat-induced de-agglomeration. Computational fluid dynamics are employed to simulate airflow patterns and particle trajectories inside the USP and Alberta throats. For all tested products, no significant differences in the in vitro aerosol performance were observed between the USP throat and the straight tube. Using fine lactose carriers (10 μm), impaction frequency and energy inside the Alberta throat were significant. Further de-agglomeration was noted inside the non-coated Alberta throat for Seretide(®) and Spiriva(®), but agglomerates emitted from Relenza(®), Ventolin(®), and Foradil(®) did not further break up into smaller fractions. The coated Alberta throat considerably reduced the FPF values of these products due to the high throat retention, but they generally agreed better with the in vivo data. In conclusion, depending on the powder formulation (including carrier particle size), the inhaler, and the induction port, further de-agglomeration could happen ex-inhaler and create differences in the in vitro measurements.

  16. THE INFLUENCE OF FIRMS STRUCTURAL CHARACTERISTICS ON THE DEGREE OF AGGLOMERATION ECONOMIES ENJOYED AMONGST FIRMS IN THE LAGOS REGION, NIGERIA

    Directory of Open Access Journals (Sweden)

    FAGBOHUNKA Adejompo

    2015-12-01

    Full Text Available Agglomeration economies is a potent tool in socio-economic revamping, rejuvenation and sustenance of regions, this is as a result of the impulse it transmitted through the multiplier effect it is capable of generated. Therefore, this paper underscores the influence of firms structural characteristics on the degree of agglomeration economies enjoyed amongst firms, using the Lagos region as a case study. The first stage in the collection of primary data involves the reconnaissance survey, thereafter one hundred and three questionnaire were administered in twelve industrial estates; one questionnaire in each of the firm. The paper reveals the following structural characteristics as germane to industrial enterprise; age of firms, areal plant size (m², capacity utilization (in percentage, and Labour size and firms investment. The paper has also found out those agglomeration economies enjoyed ranges from transportation, labour, power supply, to joint water supply. The Roy’s Largest Root test employed to test for the significance of the canonical correlations at 0.05 significant levels shows the calculated F-value 3.5247 and the tabulated F-value 2.90. This suggests that the degree of agglomeration economies enjoyed by firms is significantly explained by the size and structural characteristics of the firms. The paper therefore recommends more and active government participation in the industrial scene, given the necessary support for the expansion of firm’s structural characteristics which will lead to increase agglomeration economies enjoyed by these firms.

  17. Conception d’un automate cellulaire non stationnaire à base de graphe pour modéliser la structure spatiale urbaine: le modèle Remus

    Directory of Open Access Journals (Sweden)

    Arnaud Banos

    2007-10-01

    Full Text Available Nous proposons dans cet article une formalisation originale des automates cellulaires géographiques, à même de mieux prendre en compte grâce à une structure de graphe le voisinage irrégulier et dynamique d’entités spatiales. Le modèle Remus permet ainsi de représenter sous la forme d’un graphe mathématique les entités spatiales du bâti et les réseaux de transport urbain (graphe urbain ; il permet aussi de calculer la distance-temps entre bâtiments par le réseau. Le modèle Remus permet l’extraction de différents graphes, dont le graphe fonctionnel des distances-temps entre les immeubles et le graphe de relations de voisinage qui représente le voisinage par le réseau pour un certain seuil de temps de trajet et pour un mode de transport donné.

  18. Identifying Spatiotemporal Interactions between Urbanization and Eco-Environment in the Urban Agglomeration in the Middle Reaches of the Yangtze River, China

    National Research Council Canada - National Science Library

    Yan Yu; Yan Tong; Wenwu Tang; Yanbin Yuan; Yue Chen

    2018-01-01

    .... After evaluating urbanization level and eco-environment quality for each city in an urban agglomeration, this framework determines key interaction factors, and employs a global regression approach...

  19. Consumption of milk and milk products in the population of the Upper Silesian agglomeration inhabitants.

    Science.gov (United States)

    Kardas, Marek; Grochowska-Niedworok, Elżbieta; Całyniuk, Beata; Kolasa, Ilona; Grajek, Mateusz; Bielaszka, Agnieszka; Kiciak, Agata; Muc-Wierzgoń, Małgorzata

    2016-01-01

    Providing the appropriate amount of nutrients at every stage of life is a key element determining the proper development and functioning of the body. Because of the nutritional value and resulting position of milk and milk products in the daily diet, this study was undertaken to assess the consumption of milk and milk products among the inhabitants of the Upper Silesian agglomeration. The survey covered 600 people, including 339 women (56.5%) and 261 men (43.5%) aged 18-78 years. To assess the consumption of milk and milk products, as a research tool an original survey with the closed-ended and open-ended questions was used. The questions concerned the characteristics of the surveyed group and various aspects of the consumption of milk and milk products. The results obtained were subjected to statistical analysis using the Statistica 10.0 program with a chi-square test for quality features. The level of consumption of milk and milk products among the Upper Silesian agglomeration inhabitants is insufficient in relation to nutrition recommendations. However, despite many controversies surrounding milk, the respondents also claimed that it played an important role in their daily diet. The most frequently consumed type of milk in the surveyed group is ultra heat treated (UHT) milk with average fat content.

  20. On the flexibility of agglomeration based physical space discontinuous Galerkin discretizations

    Science.gov (United States)

    Bassi, F.; Botti, L.; Colombo, A.; Di Pietro, D. A.; Tesini, P.

    2012-01-01

    In this work we show that the flexibility of the discontinuous Galerkin (dG) discretization can be fruitfully exploited to implement numerical solution strategies based on the use of elements with very general shapes. Thanks to the freedom in defining the mesh topology, we propose a new h-adaptive technique based on agglomeration coarsening of a fine mesh. The possibility to enhance the error distribution over the computational domain is investigated on a Poisson problem with the goal of obtaining a mesh independent discretization. The main building block of our dG method consists of defining discrete polynomial spaces directly on physical frame elements. For this purpose we orthonormalize with respect to the L2-product a set of monomials relocated in a specific element frame and we introduce an easy way to reduce the cost related to numerical integration on agglomerated meshes. To complete the dG formulation for second order problems, two extensions of the BR2 scheme to arbitrary polyhedral grids, including an estimate of the stabilization parameter ensuring the coercivity property, are here proposed.