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To overcome the drawbacks of strong polarity and easy agglomeration of ordinary magnesium hydroxide (MH), hydrothermal modification is customary applied to achieve its excellent dispersion as well as controllable morphology and particle size. In this paper, the influence mechanism of hydrothermal modification is elaborated from microstructure of MH. Structures and surface energy of crystal planes, affinity of water molecules for crystal planes, and crystal growth process are calculated by Materials Studio software. Furthermore, molecular dynamics simulations about solid–liquid interface model of MH and 1 mol L−1 NaOH solution at different temperatures are performed based on the theory of modified attachment energy model. The results indicate that (0 0 1) plane with the smallest surface energy has the strongest thermodynamic stability, equipping modified crystals with lamellar morphology and excellent dispersion. (0 0 1) plane cannot be dissolved easily because of the smallest affinity of water molecules. The magnesium atoms and hydroxyl groups on (1 0 1) plane dissolved are absorbed on (0 0 1) plane, resulting in the large value of I001/I101 in the X‐ray diffraction pattern. The relative growth rate of (1 0 1) plane R101 decreases with the increasing temperature, explaining why crystals become thicker with raising temperature. [ABSTRACT FROM AUTHOR]

The nanocrystalline Ni0.4Cu 0.3Zn0.3Fe2O4ferrite is prepared by sol–gel method by doping Ta2O5 (0 to 10 wt%). This paper presents effect of Ta2O5 doping on electrical and dielectric properties of nanocrystalline NiCuZn ferrite. The XRD patterns of the synthesized samples reveal single phase cubic structure and show the secondary phase of FeTaO4 with increasing Ta2O5 composition. From FESEM, agglomeration of spherical particles is observed. Direct current electrical resistivity is measured by two probe method. The investigated ferrite samples exhibits semiconducting nature property as resistivity decreased with the increase in temperature. The variation of dielectric constant and dielectric loss tangent for all samples are presented as a function of the frequency. The result also shows that as frequency is increased there is an increase in alternating current conductivity at room temperature. [ABSTRACT FROM AUTHOR]

In this paper we combine two strands of the empirical literature on agglomeration economics. We calculate two indices to identify local industries where agglomeration externalities could be expected to be particularly strong. The main part of the paper is an econometric analysis using a dynamic panel data model to test whether dynamic employment growth is indeed stronger in these observations. Spatial dependence is taken into account by including spatially lagged exogenous variables. We use panel data on all Western German employees subject to social security from 1989 to 2006 in 326 districts and 191 industries. We find evidence that long run employment growth is significantly more persistent in industrial agglomerations. [ABSTRACT FROM AUTHOR]

The effect of three major influence process parameters, carbon addition ratio, ore particle size, and coal particle size on the compressive strength of high-alumina iron ore-coal composite hot briquette (Al-CCB) with the application of response surface methodology is investigated in this paper. The results show that, with using multiple regression analysis, the experimental data can be fitted into a quadratic polynomial model. Based on the coefficient of determination ( R2 = 0.9883) and the analysis of variance (ANOVA), the model shows good agreement with the experimental data. The effect on the compressive strength of Al-CCB from big to small is carbon addition ratio, ore particle size, and coal particle size. In order to obtain the Al-CCB with 600 N of compressive strength, the optimal experiment conditions are found to be the coal addition ratio of 16.44%, ore particle size of −100 mesh and coal particle size of −100 mesh, resulting in an actual compressive strength of 613 N, as compared to the model prediction of 600 N. This paper can provide guidance for the optimization on preparation of Al-CCB. Also, it can offer reference for the process improvement of other ore-coal composite agglomerates. [ABSTRACT FROM AUTHOR]

This paper introduces the theme of the special issue 'Agglomerations and the Rise of Urban Network Externalities'. Urban network externalities are defined as external economies from which firms and households can benefit by being located in agglomerations that are well embedded in networks that connect with other agglomerations. The contributions focus on the conceptualization of urban network externalities and their influence on urban performance. Finally, a research agenda is presented, that should focus on multiplexity and heterogeneity in networks and their impacts; interrelations between agglomerations and networks and their dynamic and place-based nature; and, the policy implications of urban network externalities. [ABSTRACT FROM AUTHOR]

Abstract: For the production of particles in fluidized beds with a monodisperse grain band spectrum usually sift‐grind cycles are used. The agglomeration phenomena occurring in this process, the disintegration, the abrasion, the overspray and the dust binding, are usually not considered individually. The aim of this research work is to determine the dependence of specific process parameters on a special fluidized bed granulation process with self‐nucleation in order to make it more controllable. For a more detailed description of this process, a simplified mathematical model is presented in this paper. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents an investigation on the influence of the production method upon crystallite and particle size, surface area and morphology of La2Zr2O7 pyrochlore. Mesoporous La2Zr2O7 nanopowders were synthesized by thermal decomposition of [Zr(sal)3(H2O)2][La(dipic)2(H2O)3]⋅3(H2O), (dipic = 2,6‐pyridinedicarboxylate, sal = salicylate), ion‐pair complex precursor as a new method. For comparative purposes, two other samples were fabricated by co‐precipitation and citrate sol‐gel methods. The ion‐pair complex precursor technique displays the low degree agglomeration, the smallest crystallite size (8.6 nm) and the highest surface area (119.20 m2/g) and total pore value (0.13 cc/g), in comparison with two other conventional methods which are related to the influence of the fabrication method. The high structural stability of the complex precursor prevents the rapid growth of particles during the calcination process and thus improves the textural properties. [ABSTRACT FROM AUTHOR]

In the present work, two main goals are followed. First, free vibrations of multiscale nanocomposite plates consist of agglomerated carbon nanotubes (CNTs), E‐glass fibers, and polymer are presented based on first‐order shear deformation theory. Mori‐Tanaka (MT) approach and fiber micromechanics are used to estimate the mechanical properties of CNT/fiber/polymer composite (CNTFPC) plate. For natural frequency analysis of the CNTFPC plate, 2‐D generalized differential quadrature (GDQ) method as an efficient and accurate numerical tool is implemented to solve the governing equations. The accuracy of the MT method and GDQ technique are examined by comparing the present results with the experimental or numerical data available in the literature. A parametric study is carried out to investigate the influences of CNTs volume fraction, CNTs agglomeration, fiber volume fraction, different geometrical parameters such as the thickness‐to‐length ratio, different laminate lay‐up (cross‐ply and angle‐ply) and various boundary conditions on the natural frequencies of CNTFPC plates. As for the second goal of the paper, stacking sequence optimization of CNTFPC plates is presented to maximize the fundamental natural frequency of the structure. The search space of optimization problem is large and consequently the optimization processes becomes too much time consuming. Therefore, a biologically‐inspired meta‐heuristic algorithm called firefly algorithm that solves optimization problems without using gradient‐based information on the objective functions and the constraints is applied to obtain the best stacking sequence of CNTFPC plate. POLYM. COMPOS., 39:1433–1446, 2018. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This study investigates the magnitude of localization economies by analysing the relocation pattern of Korean establishments in the manufacturing sector. Relocation of establishments is identified by their move across the border of wards, counties, or cities and distinguished between beyond and within their workers' commuting distance. It seems that relocation beyond commuting distance costs more than that within commuting distance since the former includes additional costs related with searching for, hiring, and training new workers. Key findings of this paper show that external benefits from agglomeration are large enough to be recognized by manufacturers through relocation beyond the border of their workers' commuting area. When the own industry's share of employment in all manufacturing industries becomes doubled through relocation, the probability for establishments to relocate over a long distance across the boundary of their workers' commuting area rises by 17 per cent. The results for sub-samples divided by the age of establishments show that older establishments are more likely to relocate over a long distance to an area with disproportionate presence of establishments in the same industry. These results seem to fit product life cycle theory by Duranton and Puga. As the production process of the product becomes standardized, the firms producing that product tend to relocate to the specialized area where they can reduce the production costs by increasing dependence on the existing intermediate input suppliers, who are more likely to appear in a more specialized area. [ABSTRACT FROM AUTHOR]

In recent years a growing body of literature has begun to consider the possible presence of path dependence in the development processes of countries. This phenomenon has always been recognized in regional and urban studies because the path of development almost naturally follows a history-dependent spatial diffusion influenced by both physical geography and the quality of institutions. In this paper, I consider the case of firm and employment concentration in Italy and its impact on local development. A large and growing literature has argued in favour of persisting effects of past institutions on current outcomes. Hence, in order to identify the impact of firm and employment density on income, I use instruments from the history of a set of Italian cities: namely the presence of a university and status as a free-city state in the Early Middle Ages. I first show that those two variables had an important effect on the process of urban development between 1300 and 1861, together with favourable geographic conditions. Then, when I use these instruments to predict firm and employment density, I find that the elasticity of income to firm and employment density is in the interval 0.08-0.13. This result is interpreted as providing evidence of the historical roots of agglomeration economies in Italy. [ABSTRACT FROM AUTHOR]

This paper analyses the effect of skill heterogeneity on regional patterns of production and housing in the presence of pecuniary externalities within a general-equilibrium framework. The analysis allows for interregional commuting. Low-skilled workers choose to live and work in the periphery, the medium-skilled commute to the core, and the highly-skilled live and work in the core. At the regional level, individual choices imply that the average skill level of employees is higher in the core regions than in the peripheral regions. In particular, in the peripheral regions, the average skill level of employees is lower than the average skill level of residents, some of whom commute to the core. [ABSTRACT FROM AUTHOR]

This paper adopts a count data model to explore the distinction between single plant and multi-plant location choices. It is hypothesized that start-up location decisions would be determined by supply variables (land, labour and capital costs, workforce and technological characteristics); demand variables (market size and market accessibility) and agglomeration economies. We use plant data and focus on location choices within Portuguese municipalities. Our research shows that new multi-plants are particularly sensitive to urbanization economies, land costs and the size of the local market, while new single plants are more responsive to labour costs, both localization and urbanization economies and accessibility to main markets. [ABSTRACT FROM AUTHOR]

ABSTRACT The paper contains a non-parametric analysis of regional convergence in the enlarged EU over the period 1998-2005. It finds overall convergence but growing within country disparities, especially due to the behaviour of newcomer regions. It also finds strong (but falling) spatial correlation of per-capita income. Starting from this evidence, the paper considers the role of socio-economic features, specialisation patterns and geographical factors in explaining within countries disparities. Overall we find that partly specialisation but more evidently socio-economic clusters have a good explanatory power while simple geographical factors do not explain within countries divergence. This does not mean that spatial factors are not important: rather it means that agglomeration alone cannot explain a complex and variegated pattern of growth where structural and socio-economic factors appear to be playing an important and increasing role. [ABSTRACT FROM AUTHOR]

ABSTRACT The advertising industry is currently undergoing a profound restructuring process, where traditional media like TV and print are being complemented and replaced by new forms of online and interactive advertising. The versatile and interactive nature of the Internet medium represents new opportunities and challenges for the advertising agencies that transcend their traditional role as developers of creative contents and campaigns. The paper discusses how this transformation process affects services in the new online market communication regime. Based on a case study on how the Internet affects the advertising industry and its related actors the paper argues that the introduction and growth of Internet-based market communication leads to a convergence of creative, strategic and technical services. It is suggested that this represents a new production and market communication space in which the end consumer often plays a more pro-active and participatory role. The paper argues that the convergence of skills and services across advertising and information and communications technology can be viewed as a Jacobian cluster mutation across related and co-evolving industrial agglomerations. The empirical findings are interpreted and conceptualised as a cyclical relationship between knowledge externalities associated with specialisation and differentiation. [ABSTRACT FROM AUTHOR]

Entry into an industry often clusters in regions where the industry is already concentrated, which is suggestive of agglomeration economies. In science-based industries research activities may exert another attracting force on entrants. Empirically these proximity effects are confounded by other influences on where entrants originate and locate. The paper begins to disentangle the effects of agglomeration, public research, and the supply of capable entrants in the German laser industry. The findings indicate that the industry's geography was primarily shaped by the local availability of potential entrants and by urbanization, but not localization economies. The impact of public research increased over time. [ABSTRACT FROM AUTHOR]

System decomposition has been widely viewed as an effective means to facilitate the comprehension of complex software systems and/or capture potentially reusable components in them. In fact, various approaches to system decomposition have been intensively documented in the literature. However, during the process of system decomposition, only a few of them can also capture the target system's hierarchical organization structure, which is essential when the target system is very complex. In this paper, we present a biting-down approach to hierarchical decomposition of object-oriented systems. Compared with the previous hierarchical approaches, the distinct features of this approach are as follows. First, our approach does not rely on agglomeration, and thus can avoid some unnecessary calculations. Second, our approach does not require merging nodes when performing high-level decomposition, and thus can avoid imprecision induced by the merging. To evaluate our approach, we conducted a case study and an experimental study on our approach. The results of these studies can confirm its effectiveness and its superiority over our previous approach. Copyright © 2009 John Wiley & Sons, Ltd. This paper presents a biting-down approach to hierarchical decomposition of object-oriented systems. The distinct features of this approach are as follows. First, our approach does not rely on agglomeration, and thus can avoid some unnecessary calculation. Second, our approach does not require merging nodes when performing high-level decomposition, and thus can avoid imprecision induced by the merging. The results of our case study and experimental study can confirm its effectiveness and its superiority over our previous approach. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

There are many fundamental issues in regional and urban economics that hinge on worker skills. This paper builds on psychological approaches to learning to characterize the role of education and agglomeration in the skill development process. While the standard approach of equating skill to worker education can be useful, there are important aspects of skill that are missed. Using a measure of skill derived from hedonic attribution, the paper explores the geographic distribution of worker traits, intelligences, and skills and considers the roles of urbanization and education in the skill development process. [ABSTRACT FROM AUTHOR]

This paper is an empirical study of the geographic and industrial scope of agglomeration economies. We also explore if small establishments make better neighbours than their larger counterparts. We address these issues by studying the effects of local industrial characteristics on the location decisions of new establishments using the random profit maximization framework. We carry out separate econometric estimations for seven industries in Catalonia, a Spanish region, using data from 1995–2002. Agglomeration economies seem to work at a very local level. Evidence of localization, urbanization and diversity effects is found. There is no strong evidence that establishments prefer to be located near to small rather than large establishments. [ABSTRACT FROM AUTHOR]

The aim of the paper is to present a review of the literature on agglomeration economies in a light such that it is possible to uncover the building blocks for use in a multidimentional approach to agglomeration economies. The paper claims that the different conceptual dimensions – industrial, socio-cultural/cognitive and geographic – build upon the three micro-foundations of agglomeration economies – indivisibility, synergy and proximity – and explain their nature, scope and intensity. The paper stresses two main issues. The first is that a socio-cultural/cognitive perspective still today ignored by mainstream approaches to agglomeration economies is an additional important conceptual dimension on which to understand the complex mechanisms whereby exchanges of knowledge, labour or intermediate goods take place in agglomerated areas. The second is that a multidimensional approach comprising the three different dimensions in the study of agglomeration economies makes it possible to overcome a deterministic approach to agglomeration economies and move instead towards a stochastic interpretation which opens the black box of this complex phenomenon. [ABSTRACT FROM AUTHOR]

Today, the importance of the Randstad agglomeration is often discussed in terms of the economic coherence between its four largest cities. This is remarkable when several leading authors argue that the economic importance of cities is strongly determined by economic networks between cities worldwide. This discrepancy stems from the fact that limited empirical research exists on corporate networks. Furthermore, the relative importance of cities within various studies is based on different functional types and spatial scales of data, making the results incomparable. Therefore, in this paper, the relative importance of the four largest Randstad cities is explored within three independent, comparative networks (top 100 global firms, top 100 European firms, and top 100 Dutch firms). Employing network analysis techniques, this paper evaluates the local, supra-regional and global importance of the four Randstad cities within the three independent networks. The results show that the relative importance and network structures of these four cities are highly dependent on the economic size and locality of the initial headquarters and that Amsterdam proves to be the most important Randstad city in all three scales of corporate networks. [ABSTRACT FROM AUTHOR]

Agglomeration economies explain why productivity increases as the size of agglomeration increases, and thereby partly explain the importance of location and space in economic development. Agglomeration economies are based on the distance between firms, labour and the market. Infrastructure investment can be a tool used by governments to affect this distance, where, in doing so, they induce agglomeration economies and increase economic growth. In this paper, we will discuss the importance of considering types of networks when analysing agglomeration economies using multiregional new economic geography (NEG)-based spatial general equilibrium models. These models typically use abstract bi-regional origin-destination networks to describe the cost of transporting or commuting between regions. These abstract networks are like tunnels between regions and do not take into account the actual roads in real infrastructure networks used for transport and traffic between destinations. In other words, in real infrastructure networks, which we label full networks, people and goods move from one region to another via actual roads and possibly via third regions. In the empirical economic literature, there is a significant difference between the economic effect of changes in a bi-regional origin-destination network and the economic effect of changes in a full network. To date, no systematic explanation has been given for this difference in the size of the effects. Lack of an explanation for this difference may lead to confusion among policy-makers who have to decide on infrastructure investment. In this methodological paper, we discuss the reason for this difference. We do not discuss the absolute size of the agglomeration effects, only the relative difference that exists when using different types of networks. In order to explain the difference, we introduce a methodology that translates the effects in a bi-regional origin-destination network into similar effects in a full network, making it possible to systematically compare the economic importance of all links (roads) in such a network. This is highly relevant to policy-makers, who can now interpret the model results on a real full infrastructure network. We will also show the mathematical relationship between the importance of agglomeration economies on a link in a full network and the importance of agglomeration economies on a link in a bi-regional origin-destination network. Finally, the methodology is illustrated with a case study from the Netherlands. [ABSTRACT FROM AUTHOR]

This paper studies AMG (algebraic multigrid) methods that utilize energy minimization construction of the interpolation matrices locally, in the setting of element agglomeration AMG. The coarsening in element agglomeration AMG is done by agglomerating fine-grid elements, with coarse element matrices defined by a local Galerkin procedure applied to the matrix assembled from the individual fine-grid element matrices. This local Galerkin procedure involves only the coarse basis restricted to the agglomerated element. To construct the coarse basis, one exploits previously proposed constraint energy minimization procedures now applied to the local matrix. The constraints are that a given set of vectors should be interpolated exactly, not only globally, but also locally on every agglomerated element. The paper provides algorithmic details, as well as a convergence result based on a ‘local-to-global’ energy bound of the resulting multiple-vector fitting AMG interpolation mappings. A particular implementation of the method is illustrated with a set of numerical experiments. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Using the Social Capital theoretical framework, territorial agglomerations of firms, such as in the industrial district, can be identified as dense strong-tie networks and are thus suitable for exploiting activities. This paper addresses the possible exploring limitations of these clustered firms. Following alternative explanations, such as the structural holes and weak tie approaches, it is proposed that local institutions may play a role as intermediary agents between external disperse networks and internal dense networks, therefore enabling these firms to deal with the requirements of an ever-changing environment. The paper also develops an empirical section where the Spanish ceramic tile industrial district is described in order to illustrate theoretical arguments. Findings suggested a number of ways in which local institutions may facilitate the creation of value for firms. Particularly, local institutions interact with many external firms and institutions and undertake research projects with local firms. In addition, some quantification of the participation of firms in the activities carried out by institutions is offered, suggesting explanations for the barriers that prevent firms from gaining direct access to external networks. [ABSTRACT FROM AUTHOR]

This paper uses municipality-level data to study firm birth in Portugal from 1986 to 1997. This is a period of significant improvements to the Portuguese motorway network raising important questions as to its impact on the spatial pattern of firm birth. The paper focuses on the effect of such large-scale road investment together with the role played by agglomeration economies for firm birth in 13 industry sectors and 9 service sectors. Motorways increase the attractiveness of locations close to the new infrastructure for most sectors. However, marked differences among sectors exist in the way transport improvements affect geographical firm-birth concentration. The results also indicate that a more diversified local economic environment encourages firm birth, but little evidence is found for agglomeration benefits stemming from sectoral specialization at the local level. [ABSTRACT FROM AUTHOR]

In the continuous casting of steel, the control of the flow to the mould is a critical issue as a constant mould level is essential for a good quality of the cast product. A stopper rod is a commonly used device to control the flow rate. Agglomeration of solid material near the stopper rod can lead to a reduced cross section and thus to a decreased casting speed or even total blockage (clogging). The mechanisms involved in clogging are still not fully understood. Single phase considerations of the flow in the region of the stopper rod result in a low or even negative pressure at the smallest cross-section. This can cause degassing of dissolved gases from the melt, evaporation of alloys and entrainment of air through the refractory material. In this paper the criteria for degassing of liquid steel at low pressures are analyzed and compared with water. A mathematical model for a two phase flow situation (liquid steel/gas) in the SEN that links the pressure distribution and the throughput with the geometrical parameters, the amount of gas in the SEN and the pressure loss coefficient at the stopper rod is presented. An explanation theory for the diminishing influence of the gas injection on clogging is outlined. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper, by using annual surveys of Chinese manufacturing firms from 2001 to 2007, investigates the relationship between industrial agglomeration and employer compliance with required pension contributions. The result of panel fixed-effect estimation shows that in the more agglomerated industrial areas, firms comply with pension mandates at a higher level. Our finding is robust to various specifications and estimations employing instrumental variables. [ABSTRACT FROM AUTHOR]

Specific small amounts of amino acids caused agglomeration of L-valine ( L-Val) crystals during evaporative crystallization from aqueous solutions. The agglomeration of L-Val occurred only under acidic condition when guest amino acids satisfied several conditions. Only L-form amino acids that have carboxylic acid groups and sufficiently long alkyl chain in the side-chains could induce agglomeration of L-Val. The length of alkyl chain in the side-chains controls the degree of agglomeration. Data indicated only 0.5 wt % of L-2-aminoadipic acid, which has a similar chemical structure to L-glutamic acid ( L-Glu), produced the large agglomerates > 1000 μm. The particle size was ∼ 500 μm when using the same amount of L-Glu. Based on the results from previous tests and this paper, the whole mechanism for the L-Val agglomeration in the presence of specific guest amino acids has been revealed. [ABSTRACT FROM AUTHOR]

Based on panel regression analysis and interviews of 70 foreign-invested enterprises ( FIEs) in 2009, this paper compares the spatial dynamics and redistribution of foreign direct investment ( FDI) from Hong Kong, Taiwan, Japan and the US in Guangdong province. We found that FDI in Guangdong tends to favour cities closer to Hong Kong, with lower wage rates, better market potential and more preferential policies, and to follow the agglomeration of FDI from the same origin. The diverse home-based characteristics have resulted into the varied pathways of spatial redistribution of FDI. Hong Kong FIEs have been searching for lower-cost regions given the rise of production cost and tightened environmental regulation. In contrast, the redistribution of FIEs from Japan and Taiwan are more sensitive to their home-based business linkages, whereas Japanese and the US FIEs tend to value access to domestic market and to expand in large cities outside Guangdong. [ABSTRACT FROM AUTHOR]

ABSTRACT An important subset of the literature on agglomeration externalities hypothesizes that intrasectoral and intersectoral relations are endogenously determined in models of local and regional economic growth. Remarkably, structural adjustment models describing the spatio-temporal dynamics of population and employment levels or growth traditionally do not include intersectoral economic dynamics. This paper argues and shows that allowing for economic linkages across sectors in these models adds considerable value, especially in forecasting. An econometric model of population-employment dynamics, in which sectoral variations in economic development are explicitly taken into account, is applied to a large urban planning policy proposal in the Netherlands. The empirical analyses suggest that population dynamics are largely exogenous, population changes drive employment in particular in the industry and retail sectors, and employment in all sectors depends strongly on intersectoral dynamics. Intersectoral dynamics appear as important drivers of regional sectoral employment changes; they are even more important than population changes, and their effect shows up clearly even within the Dutch institutional context where strict regulatory housing and planning restrictions are enforced. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper expands the literature on agglomeration economies in three ways. It disentangles amenity and productivity effects of agglomeration; it decomposes aggregate scale effects into agglomeration factors of interest to policy makers; and it estimates own effects and spillovers to neighbors. It proposes a spatial simultaneous equations model in a spatial equilibrium framework with three agents-workers, consumers, and producers of traded-goods and housing. Results for Ohio counties estimate economies resulting from population size, agglomeration causes, and public service quality and cost on each of the three agents in own and neighboring counties. [ABSTRACT FROM AUTHOR]

ABSTRACT An empirical regularity designated as the Number-Average Size (NAS) Rule was first identified for the case of Japan by , and subsequently extended to the United States by . This rule asserts a negative log-linear relation between the number and average population size of cities where a given industry is present. In this paper, we utilize the cluster-identification methodology developed by to sharpen this notion of 'industrial presence' by focusing only on cities that constitute at least part of a significant spatial agglomeration for the given industry. Our key result is to show that the NAS rule continues to hold (even more strongly) under this sharper definition. [ABSTRACT FROM AUTHOR]

In this paper we examine one aspect of agglomeration, namely the geography of human capital. In some contexts, human capital may be very mobile, and understanding local agglomeration processes therefore requires us to consider inter-regional flows of human capital. In particular, here we discuss the flows of students in Great Britain from domicile into university and then the flows of graduate human capital from university into first employment. We then estimate the local/non-local pattern of these flows as a function of the characteristics of the university, of the student population, and of the local region. Our findings suggest that university attendance in Great Britain is generally associated with very significant levels of human capital mobility, and only certain types of higher education institutions play a significant employment role in their local economies. [ABSTRACT FROM AUTHOR]

This paper describes the development of an efficient and accurate algebraic multigrid finite element solver for analysis of linear elasticity problems in two-dimensional thin body elasticity. Such problems are commonly encountered during the analysis of thin film devices in micro-electro-mechanical systems. An algebraic multigrid based on element interpolation is adopted and streamlined for the development of the proposed solver. A new node-based agglomeration scheme is proposed for computationally efficient, aggressive and yet effective generation of coarse grids. It is demonstrated that the use of appropriate finite element discretization along with the proposed algebraic multigrid process preserves the rigid body modes that are essential for good convergence of the multigrid solution. Several case studies are taken up to validate the approach. The proposed node-based agglomeration scheme is shown to lead to development of sparse and efficient intergrid transfer operators making the overall multigrid solution process very efficient. The proposed solver is found to work very well even for Poisson's ratio >0.4. Finally, an application of the proposed solver is demonstrated through a simulation of a micro-electro-mechanical switch. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

One important goal to be achieved in the colloidal processing of ceramics is to fully disperse a solid substance into finely divided particles in a liquid medium to avoid the generation of agglomerates. A novel preparation method of aqueous ceramic slurries is described in this paper. The process can be characterized by creating a chemically grafted dispersant molecule layer on particles' surfaces which is very soluble in water. The tuned configuration of dispersant molecules causes neither bridging nor depletion flocculation but induces steric repulsion effectively. The obtained aqueous slurry was quite stable and yielded green bodies with high relative density. [ABSTRACT FROM AUTHOR]

This paper examines which types of individuals are attracted to or repelled from rural and urban areas in France. Migration decisions among urban centers, suburbs, and rural areas are examined for three age groups. Differences between locations are assumed to be driven by agglomeration economies and externalities resulting from densities. We therefore stress the role of labor-market size, land markets, and commuting time in migration decisions. The results from multinomial mixed logits show that large labor markets attract the youngest and in particular educated individuals. Larger family size favors migration from city centers to suburbs, whereas divorce and widowhood increase the probability of moving to an urban center. [ABSTRACT FROM AUTHOR]

The present paper deals with element-based algebraic multigrid (AMGe) methods that target linear systems of equations coming from finite element discretizations of elliptic partial differential equations. The individual element information (element matrices and element topology) is the main input to construct the AMG hierarchy. We study a number of variants of the spectral agglomerate AMGe method. The core of the algorithms relies on element agglomeration utilizing the element topology (built recursively from fine to coarse levels). The actual selection of the coarse degrees of freedom is based on solving a large number of local eigenvalue problems. Additionally, we investigate strategies for adaptive AMG as well as multigrid cycles that are more expensive than the V-cycle utilizing simple interpolation matrices and nested conjugate gradient (CG)-based recursive calls between the levels. The presented algorithms are illustrated with an extensive set of experiments based on a matlab implementation of the methods. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The aim of this paper is to analyse the impact on firms' productivity of innovative activities and agglomeration effects among firms belonging to Marshallian industrial districts and the possible joint effect of these two forces. We study a sample of 2,821 firms active in the Italian manufacturing industry in the period 1992–1995. Our analysis uses an original data set based on three different Istituto Nazionale di Statistica statistical sources—Community Innovation Survey, Archivio Statistico delle Imprese Attive (Italian Business Register), and Sistema dei Conti delle Imprese (Italian Structural Business Statistics)—to estimate an “augmented” Cobb-Douglas production function to account for the impact of technological innovations and district-specific agglomeration effects on a firm's productivity growth. Our data set allows us to distinguish between product and process innovations, thus, through econometric analysis, we hope to achieve a better understanding of which of these two types of innovative activities benefits most from participation in an industrial district. Our empirical results show that belonging to an industrial district and making product innovations are key factors in the productivity growth of firms and that product innovations appear to have a greater effect on the economic performance of district rather than non-district firms. [ABSTRACT FROM AUTHOR]

By reducing the cost of performing isolated economic activities in remote areas, information technology might serve as a substitute for urban agglomeration. The paper assesses this hypothesis using data on Italian households' usage of the Internet, e-commerce, and e-banking. The results do not support the argument that the Internet reduces the role of distance. Internet usage is much more frequent among urban consumers than among their non-urban counterparts. The use of e-commerce is basically unaffected by the size of the city where the household lives. Geographically remote consumers are discouraged from purchasing goods by the fact that they cannot inspect them beforehand. Leisure activities and cultural items (i.e., books, CDs, and tickets for museums and theaters) are the only goods and services for which e-commerce is used more in isolated areas. Finally, e-banking bears no relationship to city size. In choosing a bank, non-urban customers give more importance to personal acquaintance than do urban clients, partly because bank account holders in remote areas are more likely to have taken out a loan from their bank. [ABSTRACT FROM AUTHOR]

This paper describes the development of a robust multigrid, finite element-based, Laplace solver for accurate capacitance extraction of conductors embedded in multi-layer dielectric domains. An algebraic multigrid based on element interpolation is adopted and streamlined for the development of the proposed solver. In particular, a new, node-based agglomeration scheme is proposed to speed up the process of agglomeration. Several attributes of this new method are investigated through the application of the Laplace solver to the calculation of the per-unit-length capacitance of configurations of parallel, uniform conductors embedded in multi-layer dielectric substrates. These two-dimensional configurations are commonly encountered as high-speed interconnect structures for integrated electronic circuits. The proposed method is shown to be particularly robust and accurate for structures with very thin dielectric layers characterized by large variation in their electric permittivities. More specifically, it is demonstrated that for such geometries the proposed node-based agglomeration systematically reduces the problem size and speeds up the iterative solution of the finite element matrix. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Concerns over the effects of globalisation and liberalisation have intensified the debates over the trajectories and underlying sources of regional inequality. This paper attempts to link macro studies of regional inequality to micro studies of local development and to expand the research on intraprovincial inequality in China to Guangdong Province. First, substantial evidence has been provided to illustrate the extent of polarisation between the Pearl River Delta (PRD) and the periphery, especially since the early 1990s. Second, it has been found that new economic spaces centred on exoproduction centres, high-tech zones, university clusters, and entrepreneurial spaces driven by the domestication of globalisation and the growth of the knowledge economy have emerged as new engines of regional growth. The orthodox notion of the PRD development as externally driven has become obsolete, and a new conceptualisation centred on the knowledge economy and integrated development better explains regional development and polarisation in Guangdong. Finally, the theoretical and policy implications of the research are discussed. The emerging form of regional development in the PRD represents an effort to make the knowledge economy the new engine of regional development and indicates that developing countries such as China are attempting to move beyond being a manufacturing assembler. The emergence of the knowledge economy in the PRD also has important implications for the recent efforts to develop the Greater Pearl River Delta, which needs to pay more attention to global networks for innovation and creativity. Moreover, the emergence of the knowledge economy makes the development of the periphery even more challenging due to the effects of self-reinforcing agglomeration and the constraints of geographical barriers. [ABSTRACT FROM AUTHOR]

This paper reports results of spatially explicit analyses of external scale effects across a variety of sectors, including manufacturing. Using data from New England counties, earnings are found to exhibit increasing returns to urbanization in every sector. Returns to sectoral localization are mixed, however, with increasing returns in one sector, constant returns in five sectors, and decreasing returns in two sectors. External scale effects are fairly confined in their spatial extent, with only retailing and services particularly marked by spillover effects from neighboring counties. [ABSTRACT FROM AUTHOR]

In this paper, we propose a model of developers' strategies for tenant mixes and the locations of shopping centers (SCs). Consumers have preferences for product variety, and tenants in the SCs sell differentiated goods. The consumers can choose two shopping behaviors: patronizing one or both of the two SCs. We show that if the consumers have strong preferences for product variety, the SCs agglomerate to free-ride on the rivals' product varieties, and the consumers patronize both SCs. On the other hand, if consumer preferences are weak, the SCs locate at different locations, and the consumers patronize one of the two SCs. [ABSTRACT FROM AUTHOR]

Standard models of the new economic geography predict that costs of living are lower in the core than in the periphery. But in reality they tend to be higher in agglomeration areas, mainly because of regional differences in housing costs. In this paper, we add a home goods sector to the seminal NEG model of Krugman (1991) . We show that a core–periphery structure can endogenously emerge in which the core is the more expensive area. This result has an important normative implication. Since higher costs of living imply falling real wages if there is no nominal wage premium, it is not desirable for everybody to live in the core region. [ABSTRACT FROM AUTHOR]

Following an outline of the different types of agglomeration economy, consideration is given to transaction costs. Transaction costs may have a definite spatial dimension because institutional, commercial, cultural, and language characteristics are differentiated across the geographic space separating market agents. The concept of transaction space is introduced to represent the spatial differentiation of these characteristics, and this concept is used to cast light on how space can contribute to coordination and agency problems that raise transaction costs. Contractual agreements that are rearranged, so as to span a less heterogeneous transaction space, permit the reduction of transaction costs. Agglomeration can then be interpreted as an alternative to hierarchical structures within firms in economizing on transaction costs. The paper concludes with illustrations of how this framework may help to understand the spatial implications of corporate restructuring and new information technologies. [ABSTRACT FROM AUTHOR]

A renewed interest in the spatial clustering or agglomeration of economic activity is evident within economic geography and related fields. This paper considers processes of change within ‘mature’ regional clusters, developing a conceptual framework which links firm-level strategies to development scenarios at the cluster level through a set of intervening mechanisms. We distinguish between two development scenarios: renewal which involves significant change, enabling the cluster to sustain its prosperity, and adjustment which is associated with stagnation and gradual decline. This conceptual framework is applied to an analysis of one key mechanism of change, diversification, as pursued by small and medium-sized enterprises (SMEs) in the Aberdeen oil cluster. Our analysis indicates that some diversification is occurring, with the implications for the cluster lying midway between adjustment and renewal. In conclusion, we emphasize the need to assess and ‘unpack’ the clusters concept and suggest that research should focus on the relationships between proximity, learning and evolution. [ABSTRACT FROM AUTHOR]

The aim of this paper is to analyze the intraurban spatial distributions of population and employment in the agglomeration of Dijon (regional capital of Burgundy, France). We study whether this agglomeration has followed the general tendency of job decentralization observed in most urban areas or whether it is still characterized by a monocentric pattern. To that purpose, we use a sample of 136 observations at the communal and at the IRIS (infraurban statistical area) levels with 1999 census data and the employment database SIRENE (INSEE). First, we study the spatial pattern of total employment and employment density using exploratory spatial data analysis. Apart from the CBD, few IRIS are found to be statistically significant, a result contrasting with those found using standard methods of subcenter identification with employment cut-offs. Next, in order to examine the spatial distribution of residential population density, we estimate and compare different specifications: exponential negative, spline-exponential, and multicentric density functions. Moreover, spatial autocorrelation, spatial heterogeneity, and outliers are controlled for by using the appropriate maximum likelihood, generalized method of moments, and Bayesian spatial econometric techniques. Our results highlight again the monocentric character of the agglomeration of Dijon. [ABSTRACT FROM AUTHOR]

Agglomeration and network externalities are fuzzy concepts. When different meanings are (un)intentionally juxtaposed in analyses of the agglomeration/network externalities-menagerie, researchers may reach inaccurate conclusions about how they interlock. Both externality types can be analytically combined, but only when one adopts a coherent approach to their conceptualization and operationalization, to which end we provide a combinatorial typology. We illustrate the typology by applying a state-of-the-art bipartite network projection detailing the presence of globalized producer services firms in cities in 2012. This leads to two one-mode graphs that can be validly interpreted as topological renderings of agglomeration and network externalities. [ABSTRACT FROM AUTHOR]

The crystallization in a fluidized‐bed crystallizer has recently received increasing interest for separation and purification of crystals. Past investigations on potassium dihydrogen phosphate (KDP) crystallization mainly focused on process efficiency and thermodynamics and less on kinetics. In this paper, the fluidized crystallization technology is used to investigate a KDP crystallization process. The mechanisms involved in crystal formation have been explored by observation of a continuous withdrawal of a suspension containing target crystals having certain size distribution. The crystallization process of KDP is researched to investigate the key parameters (suspension density [MT], solution supersaturation [ΔC], and fluid shear force [expressed by circulation flow rate; Re]) influencing crystal growth, nucleation, and agglomeration process. Three proposed crystallization kinetic models about crystals growth, nucleation, and agglomeration rates are developed and validated against data from the fluidized‐bed crystallizer. Taking advantage of multivariate nonlinear regression analysis, crystallization kinetic parameters are obtained by adopting the kinetic model in fluidized‐bed crystallization process. The comparative research of three crystallization kinetic rates is also studied. The results indicated that the parameters given by the kinetic mathematics model fit well with the experimental data. The error rate between the experimental and calculated value is also controlled within a reasonable range. [ABSTRACT FROM AUTHOR]

The article discusses a study which analyzed the influence of vertical differentiation on the location configuration of firms. The researchers found that while the principle of minimum differentiation in location may be supported, the principle of maximum differentiation in location is not applicable if companies be involved in spatially discriminatory pricing. They also proved that spatial agglomeration affects the distinct location equilibrium in the cases where companies charge the mill prices.

Physical and economic geography both contribute to low levels of income in Africa. The small size of African countries and markets impedes growth through a number of mechanisms. The business environment is prone to monopoly and opportunistic behaviour. Cities are relatively small. Public goods (national and regional are undersupplied). The potential benefits of natural resources are not dispersed widely enough. Growth prospects require better use of natural resource revenues and the development of clusters of export oriented manufacturing in coastal economies. [ABSTRACT FROM AUTHOR]