Influence du mûrissement sur l’évolution des propriétés mécaniques et structurales de l’alliage AlSi12Cu1Mg

This study is firstly to determine a compromise between strength and ductility of parts made of AlSi12Cu1Mg designated by EN AC-47100, on the other hand, it aims to evaluate the influence of curing time on behavior and damage in tension and impact, Brinell hardness, microhardness and microstructure considering the states: cast, tempered, and matured. The addition of 12% silicon (gives excellent casting properties), 1% copper (facilitates machining), and magnesium up to 1% to the aluminum are the main vectors and agents of improvement of the mechanical characteristics in addition to the specific heat treatments which reveal precipitates of different kinds (Al2Cu, Mg2Si, Si, Cu, Mg) which interfere with the displacement of the dislocations.La présente étude consiste d’une part à déterminer un compromis entre la résistance et la ductilité des pièces en AlSi12Cu1Mg désigné par la famille EN AC-47100, d’autre part, elle a pour but d’évaluer l’influence du temps de mûrissement sur le comportement et l’endommagement en traction et au choc, la dureté Brinell, la microdureté et la microstructure en considérant les états : brut de coulée, trempé, et maturé. L’ajout de 12% de silicium (donne d'excellentes aptitudes à la coulée), de 1% de cuivre (facilite l’usinage), et du magnésium jusqu’à 1% à l’aluminium, sont les principaux vecteurs et agents d’amélioration des caractéristiques mécaniques en plus des traitements thermiques spécifiques qui font apparaître des précipités de différents genres (Al2Cu, Mg2Si, Si, Cu, Mg) qui interfèrent le déplacement des dislocations.La présente étude consiste d’une part à déterminer un compromis entre la résistance et la ductilité des pièces en AlSi12Cu1Mg désigné par la famille EN AC-47100, d’autre part, elle a pour but d’évaluer l’influence du temps de mûrissement sur le comportement et l’endommagement en traction et au choc, la dureté Brinell, la microdureté et la microstructure en considérant les états : brut de coulée, trempé, et maturé. L’ajout de 12% de silicium (donne d'excellentes aptitudes à la coulée), de 1% de cuivre (facilite l’usinage), et du magnésium jusqu’à 1% à l’aluminium, sont les principaux vecteurs et agents d’amélioration des caractéristiques mécaniques en plus des traitements thermiques spécifiques qui font apparaître des précipités de différents genres (Al2Cu, Mg2Si, Si, Cu, Mg) qui interfèrent le déplacement des dislocations

Internal Medicine

Our objective was to develop a model to predict the length of stay of patients using data from MCV. We conducted our analysis using a dataset of over 130,000 patients described by 66 features. The features contained clinical characteristics (e.g. diagnosis), facility characteristics (e.g. bed type), and socioeconomic characteristics (e.g. insurance type). Our study was focused on patients that stayed in the hospital. To cope with data imperfections, such as missing data, we applied data cleaning methods. Using learned domain knowledge, we identified 9 features to build our predictive models: admit source, primary insurance, discharge disposition, admit unit, iso result, icu order, stepdown order, general care order, and age. Regression algorithms were then applied for length of stay prediction, using two views: one with the complete dataset, and the second decomposed independently into ten most popular diagnosis outcomes. We then used regression to model the length of stay using the whole dataset as well as splitting the patients by diagnosis. This division was dictated by a high variance within the data. Obtained machine learning models were embedded in a web application created via Angular. The app allows the user to pick which disease they are modeling, the specific model(s) to use, and the values for the variables. It then computes the result and displays visualization of the weights.https://scholarscompass.vcu.edu/capstone/1176/thumbnail.jp

A near optimal algorithm for lifetime optimization in wireless sensor networks

International audienceA problem that has received a lot of interest in wireless sensor networks (WSN) is lifetime optimization. Indeed, in WSN each sensor node is battery powered and it is not convenient to recharge or replace the batteries in many cases, especially in remote and hostile environments. In this paper, we introduce an efficient energy-aware algorithm to enhance the lifetime of WSN by i) organizing/clustering the sensor nodes into disjoint cover sets where each cover set is capable of monitoring all the targets of the region of interest and ii) scheduling these cover sets successively/periodically. This study differs from previous works for the following reasons: i) it achieves near optimal solutions compared to the optimal ones obtained by the exact method and ii) unlike existing algorithms that construct gradually cover sets one after the other, our algorithm builds the different sets in parallel. Indeed, at each step of the clustering process, the algorithm attempts to add to each cover set a sensor capable of monitoring the most critical target (a critical target is defined to be the one covered by the smallest set of sensors). The choice of a sensor to be placed/clustered in each cover set is based on solving a linear assignment problem. The proposed algorithm provides a lower bound Kmin of the optimal number of disjoint cover sets Kopt . Intuitively, the upper bound Kmax of the optimal value is given by the size of the smallest set of sensors covering a target. We deduce Kopt by performing a binary search procedure. At each step of the binary search process, we check if there exists a partition of the sensors in K cover sets by solving an integer programming problem. Simulation results show the efficiency of our algorithm

Critical Path Scheduling Parallel Programs on an Unbounded Number of Processors

International audienceIn this paper we present an efficient algorithm for compile-time scheduling and clustering of parallel programs onto parallel processing systems with distributed memory, which is called The Dynamic Critical Path Scheduling DCPS. The DCPS is superior to several other algorithms from the literature in terms of computational complexity, processors consumption and solution quality. DCPS has a time complexity of O (e + v\log v), as opposed to DSC algorithm O((e + v)\log v) which is the best known algorithm. Experimental results demonstrate the superiority of DCPS over the DSC algorithm

Genome Integrity: A new open access journal

The full and final version of this article can be found at the link belowThis article has been made available through the Brunel Open Access Publishing Fund.This article is available through the Brunel Open Access Publishing Fund

Iso-Level CAFT: How to Tackle the Combination of Communication Overhead Reduction and Fault Tolerance Scheduling

To schedule precedence task graphs in a more realistic framework, we introduce an efficient fault tolerant scheduling algorithm that is both contention-aware and capable of supporting $\varepsilon$ arbitrary fail-silent (fail-stop) processor failures. The design of the proposed algorithm which we call Iso-Level CAFT, is motivated by (i) the search for a better load-balance and (ii) the generation of fewer communications. These goals are achieved by scheduling a chunk of ready tasks simultaneously, which enables for a global view of the potential communications. Our goal is to minimize the total execution time, or latency, while tolerating an arbitrary number of processor failures. Our approach is based on an active replication scheme to mask failures, so that there is no need for detecting and handling such failures. Major achievements include a low complexity, and a drastic reduction of the number of additional communications induced by the replication mechanism. The experimental results fully demonstrate the usefulness of Iso-Level~CAFT

Elastic characterization by Ultrasonic waves of the unstandardized polycrystalline alloy 42500

The objective of this work is to determine the impact of the temper heat treatment (150, 160, 170, 180, 190, 200,220 and 240) °C on the evolution of the main elastic and structural properties of the alloy foundry AlSi7Zn3Cu2Mg (42500). This alloy will be subjected to precipitation hardening. This is one of the most successful methods to considerably improve the mechanical properties of the alloy, this allows choosing the compromise of high resistances while maintaining satisfactory ductility. The mechanical properties are governed by the combination of four factors: heat treatments, molding process, chemical composition and the shape of the specimen used. We used mainly four techniques namely: The ultrasonic method for the determination of the elastic characteristics, the Brinell hardness HB and the micro hardness Hv to identify the stress field, the Kcv resilience to provides information on fracture mode, brittleness and the impact resistance, and finally to completely identify the alloy, it will be followed by its metallography, microstructure and fracture surface in resilience.The purpose of this work is to study the structural hardening of the alloy AlSi7Zn3Cu2Mg (42500) by considering ten states: crude of casting noted: F taken as reference state. To improve the mechanical characteristics obtained from the crude of castingstate, a structural hardening heat treatment is carried out, the addition of magnesium is necessary in order to make the alloy sensitive to this specific heat treatment T46

Slow plasmon modes in polymeric salt solutions

The dynamics of polymeric salt solutions are presented. The salt consists of chains $\rm A$ and $\rm B$, which are chemically different and interact with a Flory-interaction parameter $\chi$, the $\rm A$ chain ends carry a positive charge whereas the $\rm B$ chain ends are modified by negative charges. The static structure factor shows a peak corresponding to a micro phase separation. At low momentum transfer, the interdiffusion mode is driven by electrostatics and is of the plasmon-type, but with an unusually low frequency, easily accessible by experiments. This is due to the polymer connectivity that introduces high friction and amplifies the charge scattering thus allowing for low charge densities. The interdiffusion mode shows a minimum (critical slowing down) at finite $k$ when the interaction parameter increases we find then a low $k$ frequency quasi-plateau.Comment: accepted in Europhys. Let

Caspase-8 Inactivation in T Cells Increases Necroptosis and Suppresses Autoimmunity in Bim−/−Bim^{−/−} Mice

Dysregulation of either the extrinsic or intrinsic apoptotic pathway can lead to various diseases including immune disorders and cancer. In addition to its role in the extrinsic apoptotic pathway, caspase-8 plays nonapoptotic functions and is essential for T cell homeostasis. The pro-apoptotic BH3-only Bcl-2 family member Bim is important for the intrinsic apoptotic pathway and its inactivation leads to autoimmunity that is further exacerbated by loss of function of the death receptor Fas. We report that inactivation of caspase-8 in T cells of $Bim^{−/−}$ mice restrained their autoimmunity and extended their life span. We show that, similar to $caspase-8^{−/−}$ T cells, $Bim^{−/−}$ T cells that also lack caspase-8 displayed elevated levels of necroptosis and that inhibition of this cell death process fully rescued the survival and proliferation of these cells. Collectively, our data demonstrate that inactivation of caspase-8 suppresses the survival and proliferative capacity of $Bim^{−/−}$ T cells and restrains autoimmunity in $Bim^{−/−}$ mice