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Obtenção de micropartículas lipídicas contendo bicarbonato de sódio por spray cooling e de bicarbonato de sódio aglomerado por melt agglomeration em leito vibrofluidizado; The obtaining of lipid microparticles containing sodium bicarbonate by spray cooling and the obtaining of sodium bicarbonate agglomerated by melt agglomeration in vibrofluidized bed

Emmanuelle Pilarski
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/02/2012 PT
Relevância na Pesquisa
36.42%
O presente trabalho teve como objetivo o desenvolvimento de (i) micropartículas lipídicas contendo bicarbonato de sódio pelo processo de spray cooling e de (ii) aglomerados de bicarbonato de sódio, utilizando-se do processo de melt agglomeration em leito vibrofluidizado. Essas tecnologias foram aplicadas com o intuito de melhorar a estabilidade desse material, uma vez que o mesmo se decompõe na presença de umidade/ou temperaturas mais elevadas. Uma mistura lipídica composta por gordura de palma totalmente hidrogenada (GPTH) e óleo de palma refinado (OP) foi empregada como material de parede/ligante que atendeu ao requisito de ponto de fusão de 55 ºC, com a proporção de 57,5 e 42,5 %, respectivamente. No processo de spray cooling, foi realizado um Delineamento Composto Central Rotacional (DCCR), com 11 ensaios, para cada um dos três diâmetros de abertura de bico atomizador estudados (??igual a 1,0; 1,2 e 1,5 mm), totalizando 33 experimentos, a fim de se avaliar o efeito da temperatura de entrada da dispersão (Te) (65 a 85 ºC) e da pressão de atomização (Pat) (1,0 a 2,0 kgf/cm2) sobre as seguintes variáveis dependentes: (i) eficiência de microencapsulação (EM, % de CO2), (ii), quantidade de bicarbonato de sódio superficial (BSS...

Estudo do processo de aglomeração com vapor e perda de qualidade por caking de achocolatados em pó; Study of the steam agglomeration process and loss of quality of cocoa beverage powder by caking

Fernanda Zaratini Vissotto
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 14/02/2014 PT
Relevância na Pesquisa
36.35%
Os achocolatados em pó são formulados com a mistura de cacau, açúcar, maltodextrina e aromas, podendo conter derivados lácteos. Para se obter uma adequada reconstituição em líquidos, os achocolatados são submetidos aos processos de lecitinação (adição de um agente tensoativo: lecitina de soja) e aglomeração com vapor. Um dos objetivos desse estudo foi o de avaliar os efeitos das variáveis do processo de aglomeração com vapor (pressão do vapor, temperatura do secador rotativo, vazão de sólidos da alimentação e frequência de rotação do secador) sobre as características físicas e físico-químicas de achocolatados em pó. A aglomeração com vapor levou a um aumento do diâmetro médio de partículas, sendo mais pronunciado no produto formulado com o açúcar moído. O processo foi responsável pelo escurecimento e redução da umidade dos achocolatados, além da diminuição dos tempos de molhabilidade. Adicionalmente foi caracterizada a morfologia dos grânulos de achocolatado, obtidos em diferentes condições operacionais do aglomerador (máxima, média e mínima), utilizando os descritores de tamanho e forma. Os resultados mostraram que não existe diferença entre os descritores de forma e quanto aos descritores de tamanho verificou-se diferença entre as condições de processo para grânulos maiores que 600 ?m. Concluiu-se que os grânulos de achocolatado aglomerados apresentaram formato alongado. Foram também determinadas as transições de fase e as temperaturas de transição vítrea (Tg) de achocolatados em pó e dos seus principais constituintes. Durante a aglomeração com vapor a alta temperatura levou o açúcar moído a uma condição acima da sua Tg...

Investigation of coalescence kinetics of microcristalline cellulose in fluidised bed spray agglomeration: experimental studies and modelling approach

Peglow,M.; Kumar,J.; Mörl,L.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 EN
Relevância na Pesquisa
36.29%
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.

Experimental study of fluidized bed agglomeration of acerola powder

Dacanal,G. C.; Menegalli,F. C.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2008 EN
Relevância na Pesquisa
36.24%
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.

Creative Destruction and Policy Reforms : Changing Productivity Effects of Firm Turnoverin Moroccan Manufacturing

Hallward-Driemeier, Mary; Thompson, Fraser
Fonte: Banco Mundial Publicador: Banco Mundial
Relevância na Pesquisa
46.33%
How important is firm turnover to national productivity growth? The literature points to the contribution of creative destruction being strongest in more developed countries or where market institutions are strongest. This paper looks at the case of Morocco, spanning 16 years, during which reform initiatives aiming to strengthen market forces were introduced. The paper argues that it is important to take into account i) the timing of how decompositions are structured (capturing the effects of high growth among young firms as part of the benefit of increased entry) and ii) the additional indirect impacts of firm dynamics on agglomeration externalities and competition. The paper shows there are striking differences in the productivity paths of entering and exiting firms compared with incumbents, and that restricting the time horizon of productivity decompositions to the actual year of entry or exit underestimates the productivity effects of turnover. Although it has been hypothesized that conducting decompositions over longer horizons would increase the positive contribution of net turnover...

Mind the Neighbors : The Impact of Productivity and Location on Firm Turnover

Hallward-Driemeier, Mary; Thompson, Fraser
Fonte: Banco Mundial Publicador: Banco Mundial
Relevância na Pesquisa
46.39%
This paper examines the impact of firm productivity and local industrial structure on firm entry and exit in Morocco between 1985 and 2001. There is strong evidence of productivity exerting a market-cleansing role. Less productive firms are found to be more likely to exit - and locations with more productive firms attract higher rates of new firm entry. The effect of productivity operates not only in an absolute sense; a firm s relative productivity or distance to the local sector frontier matters too. First, large productivity gaps are associated with higher rates of exit, while new firms are attracted to locations with small productivity gaps. Second, local competition increases the probability of exit, although it does not encourage entry. Third, there is evidence of scale or agglomeration effects that increase firm turnover. Fourth, measures of sector diversity are not associated with lower turnover. Fifth, the geographic level at which agglomeration and competition effects are defined matters differently for exit than entry. For exit...

The Persistence of (Subnational) Fortune : Geography, Agglomeration, and Institutions in the New World

Maloney, William F.; Caicedo, Felipe Valencia
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
Relevância na Pesquisa
36.24%
Using subnational historical data, this paper establishes the within country persistence of economic activity in the New World over the last half millennium. The paper constructs a data set incorporating measures of pre-colonial population density, new measures of present regional per capita income and population, and a comprehensive set of locational fundamentals. These fundamentals are shown to have explanatory power: native populations throughout the hemisphere were found in more livable and productive places. It is then shown that high pre-colonial density areas tend to be dense today: population agglomerations persist. The data and historical evidence suggest this is due partly to locational fundamentals, but also to classic agglomeration effects: colonialists established settlements near existing native populations for reasons of labor, trade, knowledge and defense. Further, high density (historically prosperous) areas also tend to have higher incomes today, and largely due to agglomeration effects: fortune persists for the United States and most of Latin America. Finally extractive institutions...

Growing through Cities in Developing Countries

Duranton, Gilles
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
Relevância na Pesquisa
36.4%
This paper examines the effects of urbanization on development and growth. It begins with a labor market perspective and emphasizes the importance of agglomeration economies, both static and dynamic. It then argues that more productive jobs in cities do not exist in a void and underscores the importance of job and firm dynamics. In turn, these dynamics are shaped by the broader characteristics of urban systems. A number of conclusions are drawn. First, agglomeration effects are quantitatively important and pervasive. Second, the productive advantage of large cities is constantly eroded and must be sustained by new job creation and innovation. Third, this process of creative destruction in cities, which is fundamental for aggregate growth, is determined in part by the characteristics of urban systems and broader institutional features. The paper highlights important differences between developing countries and more advanced economies. A major challenge for developing countries is to reinforce the role of their urban systems as drivers of economic growth.

Agglomeration Economies and Productivity in Indian Industry

Lall, Somik; Shalizi, Zmarak; Deichmann, Uwe
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
Relevância na Pesquisa
36.29%
"New" economic geography theory, and the development of innovative methods of analysis have renewed interest in the location, and spatial concentration of economic activities. The authors examine the extent to which agglomeration economies contribute to economic productivity. They distinguish three sources of agglomeration economies: 1) At the firm level, from improved access to market centers. 2) At the industry level, from enhanced intra-industry linkages. 3) At the regional level, from inter-industry urbanization economies. The input demand framework they use in analysis, permits the production function to be estimated jointly with a set of cost shares, and, makes allowances for non-constant returns to scale, and for agglomeration economies to be factor-augmenting. They use firm-level data for standardized manufacturing in India, together with spatially detailed physio-geographic information that considers the availability, and quality of transport networks linking urban centers - thereby accounting for heterogeneity in the density of transport networks...

Firm Productivity and Infrastructure Costs in East Africa

Iimi, Atsushi; Humphrey, Richard Martin; Melibaeva, Sevara
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Trabalho em Andamento
EN_US
Relevância na Pesquisa
36.36%
Infrastructure is an important driving force for economic growth. It reduces trade and transaction costs and stimulates the productivity of the economy. Africa has been lagging behind in the global manufacturing market. Among others, infrastructure is an important constraint in many African countries. Using firm-level data for East Africa, the paper reexamines the relationship between firm performance and infrastructure. It is shown that labor costs are by far the most important to stimulate firm production. Among the infrastructure sectors, electricity costs have the highest output elasticity, followed by transport costs. In addition, the paper shows that the quality of infrastructure is important to increase firm production. In particular, quality transport infrastructure seems to be essential. The paper also finds that agglomeration economies can reduce firm costs. The agglomeration elasticity is estimated at 0.03–0.04.

Firms’ Locational Choice and Infrastructure Development in Tanzania

Iimi, Atsushi; Humphreys, Richard Martin; Melibaeva, Sevara
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Trabalho em Andamento
EN_US
Relevância na Pesquisa
36.32%
Agglomeration economies are among the most important factors in increasing firm productivity. However, there is little evidence supportive of this in Africa. Using the firm registry database in Tanzania, this paper examines a new application of the logit approach with two empirical issues taken into account: spatial autocorrelation and endogeneity of infrastructure placement. The paper finds significant agglomeration economies. It is also found that firms are more likely to be located where local connectivity and access to markets are good. The paper finds that dealing with infrastructure endogeneity and spatial autocorrelation in the empirical model is important. According to the exogeneity test, infrastructure variables are likely endogenous. The spatial autoregressive term is significant. As expected, therefore, there are positive externalities of firm location choice around the neighboring areas.

Gold Mining and Proto-Urbanization

Fafchamps, Marcel; Koelle, Michael; Shilpi, Forhad
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Trabalho em Andamento
EN_US
Relevância na Pesquisa
46.35%
Central place theory predicts that agglomeration can arise from external shocks. This paper investigates whether gold mining is a catalyst for proto-urbanization in rural Ghana. Using cross-sectional data, the analysis finds that locations within 10 kilometers from gold mines have more night light and proportionally higher employment in industry and services and in the wage sector. Non-farm employment decreases at 20–30 kilometers distance to gold mines. These findings are consistent with agglomeration effects that induce non-farm activities to coalesce in one particular location. This paper finds that, over time, an increase in gold production is associated with more wage employment and apprenticeship, and fewer people employed in private informal enterprises. It also finds that the changes arising from increasing gold production are not reversed when large gold mines shrink. However this pattern cannot be ascribed unambiguously to agglomeration effects, given an increase in informal mining after formal mines decrease output is also observed.

Strategies for Urbanization and Economic Competitiveness in Burundi

World Bank Group
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Relatório
EN_US
Relevância na Pesquisa
36.16%
This report argues that urbanization brings significant opportunities for both rural and urban areas and that Burundi needs to prioritize issues of economic growth and job creation. Based on a diagnostic evaluation of the current urbanization and spatial growth, GDP, and job potential, the report highlights the importance of prioritizing policies and investments to address deficiencies in Burundi urbanization. These remedial actions will help prepare Burundi for coming urban growth and help leverage agglomeration effects, minimize negative externalities associated with rapid urbanization, and potentially reap the demographic dividend of this transition. Getting urbanization right will need to be associated with targeted implementation strategies for growth in the agribusiness and tourism sectors. A rapid move to cities is a central element of Burundi development strategy, including an increase in the urbanization rate from 11 percent to 40 percent by 2025. Burundi vision 2025 aims to aims to promote urbanization via rural-urban migration...

Vertical industry relations, spillovers and productivity: Evidence from Chilean plants

Lopez, Ricardo; Suedekum, Jens
Fonte: Center for Applied Economics and Policy Research Publicador: Center for Applied Economics and Policy Research
Tipo: Trabalho em Andamento Formato: 175253 bytes; application/pdf
EN_US
Relevância na Pesquisa
36.24%
We use disaggregated data on Chilean plants, and the Chilean input-output table to examine the impact of agglomeration spillovers on total factor productivity (TFP). In common with previous studies, we find evidence of intra-industry spillovers, but no evidence of cross-industry spillovers in general. This picture changes, however, when we take vertical industry relations into account. We find important productivity spillover effects from plants in upstream industries. Interestingly, a similar effect cannot be found from plants in downstream industries. The number of plants in these sectors has no effect on firm level TFP, just as the number of plants in other industries that are neither important upstream suppliers nor downstream customers also has no effect. Agglomeration effects are stronger for small than for large plants.

Sources of Welfare Disparities Across and Within Regions of Brazil : Evidence from the 2002-03 Household Budget Survey

Skoufias, Emmanuel; Katayama, Roy
Fonte: Washington, DC: World Bank Publicador: Washington, DC: World Bank
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
ENGLISH
Relevância na Pesquisa
46.12%
Brazil's inequalities in welfare and poverty across and within regions can be accounted for by differences in household attributes and returns to those attributes. This paper uses Oaxaca-Blinder decompositions at the mean as well as at different quantiles of welfare distributions on regionally representative household survey data (2002-03 Household Budget Survey). The analysis finds that household attributes account for most of the welfare differences between urban and rural areas within regions. However, comparing the lagging Northeast region with the leading Southeast region, differences in returns to attributes account for a large part of the welfare disparities, in particular in metropolitan areas, supporting the presence of agglomeration effects in booming areas.

Determinants of Choice of Migration Destination

Fafchamps, Marcel; Shilpi, Forhad
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
ENGLISH
Relevância na Pesquisa
36.12%
Internal migration plays an important role in moderating regional differences in well-being. This paper analyzes migrants' choice of destination, using Census and Living Standard Surveys data from Nepal. The paper examines how the choice of a migration destination is influenced by income differentials, distance, population density, social proximity, and amenities. The study finds population density and social proximity to have a strong significant effect: migrants move primarily to high population density areas where many people share their language and ethnic background. Better access to amenities is significant as well. Differentials in expected income and consumption expenditures across districts are found to be relatively less important in determining migration destination choice as their effects are smaller in magnitude than those of other determinants. The results of the study suggest that an improvement in amenities (such as the availability of paved roads) at the origin could slow down out-migration substantially.

The impact of agglomeration effects and accessibility on wages

Matas i Prat, Anna; Raymond Bara, José Luis; Roig Sabaté, José Luis
Fonte: Xarxa de Referència en Economia Aplicada (XREAP) Publicador: Xarxa de Referència en Economia Aplicada (XREAP)
Tipo: Trabalho em Andamento Formato: application/pdf
Publicado em //2011 ENG
Relevância na Pesquisa
36.24%
This paper contributes to the empirical literature on the effects of agglomeration and road accessibility on productivity of firms by looking at the case of Spain. We approach productivity indirectly by using individual wages allocated at the NUTS III level. We use a repeated cross-section of individual micro-data for the years 1995, 2002 and 2006. The availability of interprovincial travel time data for each of the three years allows controlling for transport improvements over the period by using a market potential variable. Additionally, agglomeration is approached by employment density and we control for localization economies, human capital externalities and a large set of individual and workplace characteristics. Estimating by instrumental variables, our results show a positive and significant effect of market accessibility on wages and non linear effect for employment density.

Agglomeration Effects in Foreign Direct Investment and the Pollution Haven Hypothesis

Wagner, UJ; Timmins, CD
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Artigo de Revista Científica Formato: 231 - 256; application/pdf
Publicado em /06/2009 EN_US
Relevância na Pesquisa
46.15%

From periphery to core: measuring agglomeration effects using high-speed rail

Ahlfeldt, Gabriel M.; Feddersen, Arne
Fonte: Spatial Economics Research Centre Publicador: Spatial Economics Research Centre
Tipo: Monograph; NonPeerReviewed Formato: application/pdf
Publicado em /03/2015 EN; EN
Relevância na Pesquisa
36.12%
We analyze the economic impact of the German high-speed rail (HSR) connecting Cologne and Frankfurt, which provides plausibly exogenous variation in access to surrounding economic mass. We find a causal effect of about 8.5% on average of the HSR on the GDP of three counties with intermediate stops. We make further use of the variation in bilateral transport costs between all counties in our study area induced by the HSR to identify the strength and spatial scope of agglomeration forces. Our most careful estimate points to an elasticity of output with respect to market potential of 12.5%. The strength of the spillover declines by 50% ever 30 minutes of travel time, diminishing to 1% after about 200 minutes. Our results further imply an elasticity of per-worker output with respect to economic density of 3.8%, although the effects seem driven by worker and firm selection.

Investigating agglomeration economies in a panel of European cities and regions

Artis, Michael; Curran, Declan; Sensier, Marianne
Fonte: Spatial Economics Research Centre (SERC), London School of Economics and Political Science Publicador: Spatial Economics Research Centre (SERC), London School of Economics and Political Science
Tipo: Monograph; NonPeerReviewed Formato: application/pdf
Publicado em /04/2011 EN; EN
Relevância na Pesquisa
36.24%
This paper investigates agglomeration economies in an annual panel of NUTS 2 and NUTS 3 city regions across France, Germany, Ireland, Italy, Spain and the UK over 1980-2006 and comparing three sub-samples to see if the effects have changed over time. We uncover evidence of long run agglomeration effects of around 6% for NUTS 2 and NUTS 3 city regions for the full sample. The underlying pattern that this data reflects is changing sectoral composition in which manufacturing was declining, to be largely replaced by services; then more recently a period of city-based economic growth with the financial and business services-led boom at its heart.