Why Do Some Places Succeed When Others Decline? A Social Interaction Model of Cluster Viability

One of the most convincing explanations papers generally provide concerning clusters in knowledge-based economies refers to the geographically bounded dimension of knowledge spillovers. Here we shall underline that location decision externalities precede local knowledge spillovers in the explanation of cluster aggregate efficiency, which thus requires us to focus on the sequential process of location and the nature of interdependences in location decision-making. To that end, we mean to associate cluster emergence with the formation of locational norms, and to study the critical parameters of their stability. These parameters relate to the type of decision externalities among more or less cognitively distant firms, which influences the weight and the resulting ambivalent role of knowledge spillovers at the aggregate level of clusters. We suggest two theoretical propositions which we test within a simple and general norm location dynamics modeling framework. We then proceed to discuss the results so obtained by comparing them with an emerging related literature based on the life cycle and viability of clustersclusters, location under decision externalities, cognitive distance, knowledge spillovers

Getting Into Networks and Clusters: Evidence on the GNSS composite knowledge process in (and from) Midi-Pyrénées

This paper aims to contribute to the empirical identification of clusters by proposing methodological issues based on network analysis. We start with the detection of a composite knowledge process rather than a territorial one stricto sensu. Such a consideration allows us to avoid the overestimation of the role played by geographical proximity between agents, and grasp its ambivalence in knowledge relations. Networks and clusters correspond to the complex aggregation process of bi or n-lateral relations in which agents can play heterogeneous structural roles. Their empirical reconstitution requires thus to gather located relational data, whereas their structural properties analysis requires to compute a set of indexes developed in the field of the social network analysis. Our theoretical considerations are tested in the technological field of GNSS (Global Satellite Navigation Systems). We propose a sample of knowledge relations based on collaborative R&D projects and discuss how this sample is shaped and why we can assume its representativeness. The network we obtain allows us to show how the composite knowledge process gives rise to a structure with a peculiar combination of local and distant relations. Descriptive statistics and structural properties show the influence or the centrality of certain agents in the aggregate structure, and permit to discuss the complementarities between their heterogeneous knowledge profiles. Quantitative results are completed and confirmed by an interpretative discussion based on a run of semi-structured interviews. Concluding remarks provide theoretical feedbacks.Knowledge, Networks, Economic Geography, Cluster, GNSS

Cognitive & Relational Distance in Alliance Networks: Evidence on the Knowledge Value Chain in the European ICT Sector

This paper deals with the firms’ motives for entering into knowledge partnerships. We start by showing that networking strategies are designed to access external knowledge whilst maintaining at the same time a sufficient level of knowledge appropriation and tradability. The ICT sector (and interplaying ones) is particularly concerned by this accessibility/appropriation trade-off. The questions of modularity, complementarity, compatibility and standardisation are critical in the formation of corporate strategic and technological partnerships. Considering that knowledge in this sector is complex and systemic, we construct a theoretical typology of knowledge partnerships by crossing the levels of cognitive and relational proximity with the knowledge phases of exploration, examination and exploitation. This typology is then tested on empirical data through the use of a classification algorithm. The dataset is based on a sample of strategic alliances in the European ICT sector extracted from SDC Platinum. We show that strategic alliances are clustered in relation to the knowledge phases (exploration, examination, exploitation), and that the alliance categories are characterised by levels of relational and cognitive distance which actually are in keeping with the theoretical predictions.knowledge networks; knowledge phases; proximities; strategic alliances; ICT sector

Balkanisation of telecommunication networks and regional development : a network economics approach (In French)

The paper focuses on the links between telecommunication networks and local development, emphasizing on the peculiar case of Metropolitan Area Networks (MAN). From tools of network economics, the paper studies the market dynamics of telecommunication networks and the infrastructure diffusion from metropolitan regions to peripheral ones. This market dynamics shows that the infrastructure offering by local communities can contribute to local development only if regulation mechanisms of co-operation between local public institutions are instituted.metropolitan area networks, network economics, competition/co-operation, local communities, local development

Network structural properties for cluster long run dynamics. Evidence from collaborative R&D networks in the European mobile phone industry

In a recent literature, the structural properties of knowledge networks have been pointed out as a critical factor for cluster structural changes and long run dynamics. Mixing evolutionary economic geography and network-based approach of clusters, this contribution aims at capturing and discussing the particular influence of hierarchy (degree distribution) and assortativity (degree correlation) in the innovative capabilities of clusters along the industry life cycle. We test our propositions in the field of the mobile phone industry in Europe from 1988 to 2008. We use EPO PATSTAT and OECD REGPAT to capture cluster trends, and R&D relations from European Framework Programs to capture knowledge networks and their evolving structural properties. Our findings provide new insights to understand the organization of clusters over time in order to perform along the industry life cycl

FROM 3D IMAGING OF STRUCTURES TO DIFFUSIVE PROPERTIES OF ANISOTROPIC CELLULAR MATERIALS

International audienceThis paper deals with diffusive properties phenomena in metallic foams. We have developed a 3D morphological tool to extract geometrical characteristics of the media from X-ray images. The anisotropy of the geometry of each phase is observed and the relationship between microstructure and effective properties is analyzed. We emphasize on geometrical tortuosity determination and impact on con¬ductive transport tensor. The conductive heat transfers are computed on a vertex-edge network to determine directional effective conductivities by solving the energy equa¬tion on this network. We realize a systematic study carried on a wide range of different Nickel foam samples. Finally, we propose a simple model of effective diffusion prop¬erties dependence on tortuosity and porosity

A new electrochemical cell with a uniformly accessible electrode to study fast catalytic reactions

International audienceThe electrochemical study of fast catalytic reactions is limited by mass transport when using the conventional electrochemical cell with a rotating disk electrode (RDE). To overcome this issue, it is important to find a new device with improved transport properties that respects electrochemical constraints. We used numerical simulations of computational fluid dynamics to design a new electrochemical cell based on the so-called “jet flow” design for the kinetic studies of catalytic chemical reactions at the surface of an electrode. The new cell is characterized by a high, reliable and uniform mass transport over the electroactive part of its surface. We investigated the effects of the nozzle and the electrode diameters, the nozzle–electrode distance and the Reynolds number on the performance of the jet-electrode in the flow system. Through the optimization of the geometry of this jet electrode cell, we achieved a factor of 3 enhancement in transport compared to the rotating disk electrode. We succeeded in constructing the designed electrode, characterized it with electrochemical techniques, and found an excellent agreement between the transport properties deduced from the numerical simulations and those from the measurements

Characterization and functionalization by sol–gel route of SiC foams

Ceramic foam materials are commonly used for various applications, including catalyst supports or solar receivers. SiC foams are good candidates for the latter application as solar receivers. Its efficiency is directly related to the geometry, which can be evidenced by X-ray microtomography, and optical properties of the receiver. A promising route to add functionalities with homogenous and adhering oxide coatings onto complex SiC foams in a single step process is proposed. This oxide synthetic process is derived from the Pechini method. Foams are fully impregnated by precursor sols with a controlled viscosity making a thin and totally covering coating