Parallel Sparse Matrix Solver on the GPU Applied to Simulation of Electrical Machines

Nowadays, several industrial applications are being ported to parallel architectures. In fact, these platforms allow acquire more performance for system modelling and simulation. In the electric machines area, there are many problems which need speed-up on their solution. This paper examines the parallelism of sparse matrix solver on the graphics processors. More specifically, we implement the conjugate gradient technique with input matrix stored in CSR, and Symmetric CSR and CSC formats. This method is one of the most efficient iterative methods available for solving the finite-element basis functions of Maxwell's equations. The GPU (Graphics Processing Unit), which is used for its implementation, provides mechanisms to parallel the algorithm. Thus, it increases significantly the computation speed in relation to serial code on CPU based systems

Measurement of overall insecticidal effects in experimental hut trials

BACKGROUND: The 'overall insecticidal effect' is a key measure used to evaluate public health pesticides for indoor use in experimental hut trials. It depends on the proportion of mosquitoes that are killed out of those that enter the treated hut, intrinsic mortality in the control hut, and the ratio of mosquitoes entering the treatment hut to those entering the control hut. This paper critically examines the way the effect is defined, and discusses how it can be used to infer effectiveness of intervention programmes. FINDINGS: The overall insecticidal effect, as defined by the World Health Organization in 2006, can be negative when deterrence from entering the treated hut is high, even if all mosquitoes that enter are killed, wrongly suggesting that the insecticide enhances mosquito survival. Also in the absence of deterrence, even if the insecticide kills all mosquitoes in the treatment hut, the insecticidal effect is less than 100%, unless intrinsic mortality is nil. A proposed alternative definition for the measurement of the overall insecticidal effect has the desirable range of 0 to 1 (100%), provided mortality among non-repelled mosquitoes in the treated hut is less than the corresponding mortality in the control hut. This definition can be built upon to formulate the coverage-dependent insecticidal effectiveness of an intervention programme. Coverage-dependent population protection against feeding can be formulated similarly. CONCLUSIONS: This paper shows that the 2006 recommended quantity for measuring the overall insecticidal effect is problematic, and proposes an alternative quantity with more desirable propertie

The unexpected importance of mosquito oviposition behaviour for malaria: non-productive larval habitats can be sources for malaria transmission

BACKGROUND: Mosquitoes commute between blood-meal hosts and water. Thus, heterogeneity in human biting reflects underlying spatial heterogeneity in the distribution and suitability of larval habitat as well as inherent differences in the attractiveness, suitability and distribution of blood-meal hosts. One of the possible strategies of malaria control is to identify local vector species and then attack water bodies that contain their larvae. METHODS: Biting and host seeking, not oviposition, have been the focus of most previous studies of mosquitoes and malaria transmission. This study presents a mathematical model that incorporates mosquito oviposition behaviour. RESULTS: The model demonstrates that oviposition is one potential factor explaining heterogeneous biting and vector distribution in a landscape with a heterogeneous distribution of larval habitat. Adult female mosquitoes tend to aggregate around places where they oviposit, thereby increasing the risk of malaria, regardless of the suitability of the habitat for larval development. Thus, a water body may be unsuitable for adult mosquito emergence, but simultaneously, be a source for human malaria. CONCLUSION: Larval density may be a misleading indicator of a habitat's importance for malaria control. Even if mosquitoes could be lured to oviposit in sprayed larval habitats, this would not necessarily mitigate – and might aggravate – the risk of malaria transmission. Forcing mosquitoes to fly away from humans in search of larval habitat may be a more efficient way to reduce the risk of malaria than killing larvae. Thus, draining, fouling, or filling standing water where mosquitoes oviposit can be more effective than applying larvicide

Automatic Multi-GPU Code Generation applied to Simulation of Electrical Machines

The electrical and electronic engineering has used parallel programming to solve its large scale complex problems for performance reasons. However, as parallel programming requires a non-trivial distribution of tasks and data, developers find it hard to implement their applications effectively. Thus, in order to reduce design complexity, we propose an approach to generate code for hybrid architectures (e.g. CPU + GPU) using OpenCL, an open standard for parallel programming of heterogeneous systems. This approach is based on Model Driven Engineering (MDE) and the MARTE profile, standard proposed by Object Management Group (OMG). The aim is to provide resources to non-specialists in parallel programming to implement their applications. Moreover, thanks to model reuse capacity, we can add/change functionalities or the target architecture. Consequently, this approach helps industries to achieve their time-to-market constraints and confirms by experimental tests, performance improvements using multi-GPU environments.Comment: Compumag 201

Persistent Organic Pollutants in a marine bivalve on the Marennes-Oléron Bay and the Gironde Estuary (French Atlantic coast) -Part 1: Bioaccumulation

International audienceThe aim of this study was to determine 1) the relevance of using the Pacific oyster Crassostrea gigas as a sentinel organism, at a juvenile stage, for polycyclic aromatic hydrocarbon (PAH) and persistent organic pollutant (polychlorobiphenyls, PCBs, polybromodimethylethers, PBDEs, and organochlorine pesticides, OCPs) contamination, 2) the potential levels of chemical organic contamination in the Marennes-Oleron Bay, and their potential sources 3) the potential influence of physiological or environmental factors on contaminant body burdens in oysters. To this end, juvenile oysters purchased from a oyster hatchery were transplanted to a reference site, in Bouin, and to different transplantation sites in the Marennes-Oléron Bay, the first oyster production area in France, and in the Gironde Estuary, the biggest estuary in Occidental Europe. Transplantations were done during summer and winter. Whole oyster soft tissues from each site were analyzed for PAHs, PCBs, PBDEs and OCPs. Results obtained with a transplantation period of 3 months suggest that the C. gigas, at the juvenile stage, is a relevant sentinel organism for short-term contamination for these contaminants. In addition, no significant effects of physiological factors on contaminant body burdens were observed. A principal component analysis performed with chemical body burdens allowed them to be separated into three groups: 1) the reference site, 2) Les Palles (LP) and Boyard (BOY) in winter and 3) all the other sites. The group of LP and BOY was clearly defined by the levels of PAHs and OCPs, suggesting higher levels of contamination of these chemical compounds on these sites, potentially due to local contamination sources. In addition, no relevant effects of physiological or environmental factors on contaminant body burdens were observed. Results suggest also a predominance of contaminants related to agricultural activities along the Marennes-Oléron Bay, and therefore, further studies on the presence of pesticides in this region should be considered

Toxicity assessment of water-accommodated fractions from two different oils using a zebrafish (Danio rerio) embryo-larval bioassay with a multilevel approach

International audiencePetroleum compounds from chronic discharges and oil spills represent an important source of environmental pollution. To better understand the deleterious effects of these compounds, the toxicity of water-accommodated fractions (WAF) from two different oils (brut Arabian Light and Erika heavy fuel oils) were used in this study. Zebrafish embryos (Danio rerio) were exposed during 96 hours at three WAF concentrations (1, 10 and 100% for Arabian Light and 10, 50 and 100% for Erika) in order to cover a wide range of polycyclic aromatic hydrocarbon (PAH) concentrations, representative of the levels found after environmental oil spills. Several endpoints were recorded at different levels of biological organization, including lethal endpoints, morphological abnormalities, photomotor behavioral responses, cardiac activity, DNA damage and exposure level measurements (EROD activity, cyp1a and PAH metabolites). Neither morphological nor behavioral or physiological alterations were observed after exposure to Arabian Light fractions. In contrast, the Erika fractions led a high degree of toxicity in early life stages of zebrafish. Despite of defense mechanisms induced by oil, acute toxic effects have been recorded including mortality, delayed hatching, high rates of developmental abnormalities, disrupted locomotor activity and cardiac failures at the highest PAH concentrations (Σ TPAHs=257029 ± 47231 ng.L-1). Such differences in toxicity are likely related to the oil composition. The use of developing zebrafish is a good tool to identify wide range of detrimental effects and elucidate their underlying foundations. Our work highlights once more, the cardiotoxic action (and potentially neurotoxic) of petroleum-related PAHs

A Metapopulation Model for Chikungunya Including Populations Mobility on a Large-Scale Network

In this work we study the influence of populations mobility on the spread of a vector-borne disease. We focus on the chikungunya epidemic event that occurred in 2005-2006 on the R\'eunion Island, Indian Ocean, France, and validate our models with real epidemic data from the event. We propose a metapopulation model to represent both a high-resolution patch model of the island with realistic population densities and also mobility models for humans (based on real-motion data) and mosquitoes. In this metapopulation network, two models are coupled: one for the dynamics of the mosquito population and one for the transmission of the disease. A high-resolution numerical model is created out from real geographical, demographical and mobility data. The Island is modeled with an 18 000-nodes metapopulation network. Numerical results show the impact of the geographical environment and populations' mobility on the spread of the disease. The model is finally validated against real epidemic data from the R\'eunion event.Comment: Accepted in Journal of Theoretical biolog

Mathematical Modelling of Mosquito Dispersal in a Heterogeneous Environment.

Mosquito dispersal is a key behavioural factor that affects the persistence and resurgence of several vector-borne diseases. Spatial heterogeneity of mosquito resources, such as hosts and breeding sites, affects mosquito dispersal behaviour and consequently affects mosquito population structures, human exposure to vectors, and the ability to control disease transmission. In this paper, we develop and simulate a discrete-space continuous-time mathematical model to investigate the impact of dispersal and heterogeneous distribution of resources on the distribution and dynamics of mosquito populations. We build an ordinary differential equation model of the mosquito life cycle and replicate it across a hexagonal grid (multi-patch system) that represents two-dimensional space. We use the model to estimate mosquito dispersal distances and to evaluate the effect of spatial repellents as a vector control strategy. We find evidence of association between heterogeneity, dispersal, spatial distribution of resources, and mosquito population dynamics. Random distribution of repellents reduces the distance moved by mosquitoes, offering a promising strategy for disease control