Institutional stability and industry renewal: diverging trajectories in the Cognac beverage cluster

Adding to approaches highlighting network dynamics as a basis for regional economic development, increased attention is paid to institutions as contextual factors contributing to explaining how and why economies change. Research has shown that firms tend to react differently to the same institutional configurations, with the main explanatory factors being their sectoral backgrounds and intra-firm characteristics. This study adds to these insights by examining a regional economy in France, that of Cognac, in which 300 firms are operating under homogeneous institutional preconditions. Despite these similarities, we identify different development trajectories from the 1990s onwards. Our observations illustrate how firms’ responses to external change diverge and bring them on different trajectories due to different positions in the industry hierarchy and different experiences and capabilities among individuals within firms. The study contributes to the better understanding of mechanisms of path dependence, which have gained wide recognition in the literature in the recent decades.     

Color tracking with contextual switching: real-time implementation on CPU

Journal of Real-Time Image Processing - The paper proposes contributions for mean-shift (MS) and covariance tracking (CT), and makes these two complementary methods cooperate. While MS runs fast...     

Impact of a satellite-derived leaf area index monthly climatology in a global numerical weather prediction model

The leaf area index (LAI), defined as the one-sided green leaf area per unit ground area, is used in many numerical weather prediction (NWP) models as an indicator of the vegetation development state, which is of paramount importance to characterize land evaporation, photosynthesis, and carbon-uptake processes. LAI is often simply represented by lookup tables, dependent on the vegetation type and seasons. However, global LAI datasets derived from remote sensing observations have more recently become available. These products are based on sensors such as the Advanced Very High Resolution Radiometer (AVHRR) or the Moderate Resolution Imaging Spectroradiometer (MODIS), onboard polar orbiting satellites that can cover the entire globe within typically 3 days and with a spatial resolution of the order of 1 km.

We examine the meteorological impact of satellite-derived LAI products on near-surface air temperature and humidity, which comes both from the stomatal transpiration of leaves and from the intercepted water on the surface of leaves, re-evaporating into the atmosphere.

Two distinct monthly LAI climatology datasets derived respectively from AVHRR and MODIS sensors are tested. A set of forecasts and data assimilation experiments with the integrated forecasting system of the European Centre for Medium-range Weather Forecasts is performed with the monthly LAI climatology datasets as opposed to a vegetation-dependent constant LAI. The monthly LAI is shown to improve the forecasts of near-surface (screen-level) air temperature and relative humidity through its effect on evapotranspiration, with the largest impact obtained over needleleaf forests, crops, and grassland. At longer time-scales, the introduction of the monthly LAI is shown to have a positive impact on the model climate particularly during the boreal spring, where the LAI climatology has a large seasonal cycle.     

Posture and muscular behaviour in emergency braking: An experimental approach

In the field of numerical crash simulations in road safety research, there is a need to accurately define the initial conditions of a frontal impact for the car occupant. In particular, human models used to simulate such impacts barely take into account muscular contracting effects. This study aims to quantify drivers’ behaviour in terms of posture and muscular activity just before a frontal impact.Experiments on volunteers were performed in order to define these conditions, both on a driving simulator and on a real moving car. Brake pedal loads, lower limbs kinematics and muscle activation were recorded.Coupling instantaneous data from both experimental protocols (simulator versus Real car), a standard emergency braking configuration could be defined as (1) joint flexion angles of 96°, 56° and 13° for the right hip, knee and ankle respectively; (2) a maximum brake pedal load of 780 N; (3) a muscular activation of 55% for the anterior thigh, 26% for the posterior thigh, 18% for the anterior leg and 43% for the posterior leg.The first application of this research is the implementation of muscle tone in human models designed to evaluate new safety systems.     

Theoretical and numerical study of strain rate influence on AA5083 formability

With the application of new forming techniques (hydroforming, incremental forming), it is necessary to improve the characterization of the formability of materials and in particular the influence of strain rate. This paper begins with the characterization of material behavior of an aluminum alloy 5083 at high temperatures. To describe its visco-plastic behavior, Swift’s hardening law is used and the corresponding parameter values are identified. Then, two different approaches are introduced to construct FLDs (forming limit diagrams) of this alloy sheet and evaluate the effect of the rate sensitivity index on its formability. The first one is theoretical (the M-K model), and an algorithm is developed to calculate the limit strains by this model. In the second approach, the Marciniak test is simulated with the commercially available finite-element program ABAQUS. Based on FEM results, different failure criteria are discussed and an appropriate one is chosen to determine the onset of localized necking. With the material behavior data corresponding to AA5083 at 150 °C, parametric studies are carried out to evaluate the effect of the strain rate sensitivity index. The comparison of results by these two approaches shows the same tendency that an improvement of the formability with increasing strain rate sensitivity is observed. Finally, by consideration of the compensating effects of the strain hardening and rate sensitivity indices, the FLDs of this sheet at 150, 240 and 300 °C are determined and compared. Results show that the formability of AA5083 seems not to be improved up to a certain temperature (between 240 and 300 °C), above this temperature, the formability is greatly enhanced.     

Path‐following algorithms and experiments for an unmanned surface vehicle

This paper addresses the problem of path following in two‐dimensional space for underactuated unmanned surface vehicles (USVs), defining a set of guidance laws at the kinematic level. The proposed nonlinear Lyapunov‐based control law yields convergence of the path‐following error coordinates to zero. Furthermore, the introduction of a virtual controlled degree of freedom for the target to be followed on the path removes singularity behaviors present in other guidance algorithms proposed in the literature. Some heuristic approaches are then proposed to face the problem of speed of advance adaptation based on path curvature measurement and steering action prediction. Finally a set of experimental results of all the proposed guidance laws, carried out with the Charlie USV, demonstrates the feasibility of the proposed approach and the performance improvements, in terms of precision in following the reference path and transient reduction, obtained by introducing speed adaptation heuristics. © 2009 Wiley Periodicals, Inc.     

Mechanistic studies of the electropolymerization of 2,2′-bithiophene and of pyrrole to form conducting polymers

The electropolymerizations of 2,2′-bithiophene and of pyrrole to form conducting polymers were investigated by several electrochemical methods. Cyclic voltammetry indicates that a peak at 1.1 V is associated with the polymer and that the same product is formed from thiophene as from 2,2′-bithiophene. The rate of polymer formation has a zero kinetic order dependence on monomer concentration for polymerization of pyrrole or 2,2′-bithiophene. A dependence on concentration of supporting electrolyte is interpreted as a consequence of anion diffusion and oxidative doping in the polymer. The kinetic results are consistent with an oxidative coupling mechanism for polymer formation. The electrochromic switching of the polymer film was investigated by spectroelectrochemical methods and the kinetics were examined over a range of film thicknesses.     

Carbon–polymer composites with extreme electrical conductivity

The aim of this study was to develop Carbon–polymer composites with extreme electrical conductivity (100 S/cm) combined with good flexural strength. Despite the many optimization methods described in the literature, no comprehensive optimization procedure was to be found because the formulation did not control by itself the final properties. This study showed the major influence of the processing conditions with these peculiar materials. A detailed study of the influence of the processing conditions on the microstructural and macroscopic properties was performed. We, thereby, proposed a comprehensive way to optimize the properties of the final product. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42274.