What Allotment and Subcontracting in Procurement Bidding

Allotment and subcontracting are the two alternative mechanisms enabling the participation of SMEs in procurement. We compare these two alternatives in the context of a procurement contract awarded by a first-price sealed-bid auction. When the winning large firm is constrained with respect to the degree of subcontracting, we show that only a reduction of the chosen SME's profit can reduce the expected cost of the contract. However, when the large firm is allowed to choose the subcontracting level, subcontracting can be a Pareto dominating mechanism, i.e. simultaneously increasing both firms' profits and reducing the expected total cost of the contract.allotment; subcontracting; procurement; bidding

Performance comparison between Java and JNI for optimal implementation of computational micro-kernels

General purpose CPUs used in high performance computing (HPC) support a vector instruction set and an out-of-order engine dedicated to increase the instruction level parallelism. Hence, related optimizations are currently critical to improve the performance of applications requiring numerical computation. Moreover, the use of a Java run-time environment such as the HotSpot Java Virtual Machine (JVM) in high performance computing is a promising alternative. It benefits from its programming flexibility, productivity and the performance is ensured by the Just-In-Time (JIT) compiler. Though, the JIT compiler suffers from two main drawbacks. First, the JIT is a black box for developers. We have no control over the generated code nor any feedback from its optimization phases like vectorization. Secondly, the time constraint narrows down the degree of optimization compared to static compilers like GCC or LLVM. So, it is compelling to use statically compiled code since it benefits from additional optimization reducing performance bottlenecks. Java enables to call native code from dynamic libraries through the Java Native Interface (JNI). Nevertheless, JNI methods are not inlined and require an additional cost to be invoked compared to Java ones. Therefore, to benefit from better static optimization, this call overhead must be leveraged by the amount of computation performed at each JNI invocation. In this paper we tackle this problem and we propose to do this analysis for a set of micro-kernels. Our goal is to select the most efficient implementation considering the amount of computation defined by the calling context. We also investigate the impact on performance of several different optimization schemes which are vectorization, out-of-order optimization, data alignment, method inlining and the use of native memory for JNI methods.Comment: Part of ADAPT Workshop proceedings, 2015 (arXiv:1412.2347

Euler-like modelling of dense granular flows: application to a rotating drum

General conservation equations are derived for 2D dense granular flows from the Euler equation within the Boussinesq approximation. In steady flows, the 2D fields of granular temperature, vorticity and stream function are shown to be encoded in two scalar functions only. We checked such prediction on steady surface flows in a rotating drum simulated through the Non-Smooth Contact Dynamics method. This result is non trivial because granular flows are dissipative and therefore not necessarily compatible with Euler equation. Finally, we briefly discuss some possible ways to predict theoretically these two functions using statistical mechanics

Sentiment d’efficacité personnelle et attente de résultat : perspectives pour le conseil en orientation

On présente des résultats montrant que le sentiment d’efficacité personnelle (SEP) à l’égard des études d’étudiants français est lié avec leur performance académique. Ces résultats sont en conformité avec la littérature scientifique internationale qui place le SEP parmi les bons prédicteurs de la performance. Il semble cependant que des effets de contexte sont à prendre en compte dans certains cas. D’autres études présentées suggèrent que, dans certaines situations, l’attente de résultat pourrait avoir un rôle plus déterminant que ce qui est généralement décrit. En effet, dans la théorie sociale cognitive de Bandura, la détermination des conduites et des performances la plus significative est celle du sentiment d’efficacité personnelle. Les implications de ces résultats pour le conseil en orientation sont discutées.We present results that show that academic self-efficacy of French students is linked with their academic achievement. These results are similar to those of international scientific literature that depicts self-efficacy as a good predictor of performance. It appears, however, that contextual effects should be taken into account in some cases. Other studies presented here suggest that outcome expectation could carry more weight in performance determination than what is generally described. Actually, in Bandura’s social cognitive theory, the most significant determination of behaviors and performance comes from self-efficacy. The implications of these results for career counseling practices are discussed

C. Lemoine. Psychologie dans le travail et les organisations

Le texte de Claude Lemoine se prête à au moins deux niveaux de lecture, informatif et réflexif. Écrit dans un style très accessible et vivant, il convient parfaitement au lecteur novice qui souhaite s’initier à la psychologie du travail et des organisations. Le lecteur déjà informé y trouvera un point de vue original et fédérateur sur ce secteur d’activités du psychologue. C’est un pari difficile de couvrir ce champ de la psychologie dans le volume restreint de la collection. Claude Lemoine y..

Fluctuation-Dissipation Relations and statistical temperatures in a turbulent von K\'arm\'an flow

We experimentally characterize the fluctuations of the non-homogeneous non-isotropic turbulence in an axisymmetric von K\'arm\'an flow. We show that these fluctuations satisfy relations analogous to classical Fluctuation-Dissipation Relations (FDRs) in statistical mechanics. We use these relations to measure statistical temperatures of turbulence. The values of these temperatures are found to be dependent on the considered observable as already evidenced in other far from equilibrium systems.Comment: four pages 2 figures one tabl

Pour une politique ambitieuse des données publiques

Ce rapport présente une étude sur la réutilisation des données publiques, menée pour la Délégation aux usages de l’Internet du Ministère de l’Enseignement supérieur et de la Recherche dans le cadre du Master d’Action Publique de l’École des Ponts ParisTech. Il met en perspective la problématique et les enjeux de l’Open Data, propose un état des lieux de la réutilisation des données publiques en France, et dessine trois scénarios prospectifs pour l’évolution future de ce mouvement. Elle présente seize propositions pour une politique nationale ambitieuse d’ouverture et de réutilisation des données publiques. Quatre élèves de l’École des Ponts ParisTech, Pierre-Henri Bertin, Romain Lacombe, François Vauglin et Alice Vieillefosse ont mené cette analyse de septembre 2010 à janvier 2011, en rencontrant les acteurs clés de la réutilisation des données publiques, en prenant part à des colloques internationaux, et en s’appuyant sur la bibliographie existante

Semi-automatic Liver Tumor Segmentation in Dynamic Contrast-Enhanced CT Scans Using Random Forests and Supervoxels

International audiencePre-operative locoregional treatments (PLT) delay the tumor progression by necrosis for patients with hepato-cellular carcinoma (HCC). Toward an efficient evaluation of PLT response, we address the estimation of liver tumor necrosis (TN) from CT scans. The TN rate could shortly supplant standard criteria (RECIST, mRECIST, EASL or WHO) since it has recently shown higher correlation to survival rates. To overcome the inter-expert variability induced by visual qualitative assessment, we propose a semi-automatic method that requires weak interaction efforts to segment parenchyma, tumoral active and necrotic tissues. By combining SLIC supervoxels and random decision forest, it involves discriminative multi-phase cluster-wise features extracted from registered dynamic contrast-enhanced CT scans. Quantitative assessment on expert groundtruth annotations confirms the benefits of exploiting multi-phase information from semantic regions to accurately segment HCC liver tumors

La commande publique par enchère électronique inversée

La récente réforme du Code des marchés publics prévoit l’usage de procédures d’enchères électroniques inversées. Sur la base des résultats récents de la littérature économique, cet article présente les avantages et inconvénients d’une telle réforme, en terme de prix de passation, d’efficacité allocative et de sensibilité à la collusion. En analysant à la fois le contexte d’une attribution d’un seul lot ou de plusieurs, selon le critère du prix ou de l’offre économiquement la plus avantageuse, cet article met en lumière l’importance d’une définition préalable rigoureuse des règles de l’enchère électronique inversée.The last reform of the French procurement regulation has introduced the possibility of awarding the contracts by means of electronic reverse auctions. According to recent literature, this article presents the benefits and drawbacks of electronic reverse auctions, in terms of expected costs and efficiency as well as the vulnerability to collusion. We consider different environments, single or multi-unit auctions and multi-attribute auctions. This article shows that the optimal design of electronic reverse auctions is very sensitive to details. This emphasizes the necessity to carefully design these auctions