Les parasites des stocks d'arachide

D'après les observations recueillies sur les divers modes de stockages et les parasites causant des dégâts dans les stocks, le stockage en coque est le plus intéressant. Les moyens de lutte chimique sont présentés

Un outil de développement forgé au Sénégal : le Service Semencier

Un projet de mise en place d'un Service Semencier du Sénégal a été mis en oeuvre au cours des 4 campagnes 1972/73 à 1975/76, par la Direction générale de la Production agricole du Sénégal. Initialement limité à l'arachide, le projet a été étendu aux semences de mils, sorghos, maïs, niébés, riz. Pour l'arachide, l'objectif était de produire chaque année par l'intermédiaire de cultivateurs contractuels les 125 000 t de semences nécessaires pour l'ensemble du pays. Les semences d'arachide collectées par le Projet sont passées de 30 000 t en 1972/73 à 147 000 t en 1975/76. Pour les espèces vivrières, l'objectif a été limité initialement à 1 000 t dès la campagne 1974/75. Outre la production de semences sélectionnées de pureté variétale et de valeur germinative élevées, le projet a assuré la mise en place d'un important dispositif de contrôle, de conditionnement et de stockage des semence

Conservation des semences d'arachide en magasins réfrigérés

Description du service semencier du Sénégal qui constitue des réserves de semences d'arachides décortiquées de la variété 55-437. La dimension et les équipements techniques des chambres réfrigérées sont présentés. Une analyse de la qualité des graines réfrigérées montre que la valeur semencière s'est maintenue à un niveau comparable à celui des graines fraîches. La qualité se maintient environ 2 mois après la sortie des graines du magasin réfrigér

Simulation of the spreading of a gas-propelled micro-droplet upon impact on a dry surface using a lattice-Boltzmann approach

Spray cooling is one of the most promising methods of cooling high heat flux electronics. Depending on the type of the nozzle, spray cooling can be categorized as single phase or two phase. In the latter, which is known to be more effective, a secondary gas is used to further pressurize the liquid and form smaller droplets at higher velocities. The gas is also assumed to assist the spreading phase by imposing normal and tangential forces on the droplet free surface which adds to the complicated hydrodynamics of the droplet impact. Moreover, the order of magnitude of droplet size in spray cooling is 10¯⁶m thereby introducing a low Weber and Reynolds numbers impact regime which heretofore has not been well understood. A 3D lattice Boltzmann method was implemented to simulate the impact of a single micro-droplet on a dry surface in both ambient air and under a stagnation gas flow. Two cases were closely compared and correlations were proposed for the instantaneous spreading diameter. Contrary to recent findings at higher impact We and Re, it was found that stagnation flow only significantly affects the spreading phase for Ca*⩾0.35 but has little influence on the receding physics

Modelling the causes and consequences of perceptions of personal safety on public transport ridership

Fears about personal safety on public transport can have an important impact on ridership. A range of studies have examined different factors that influence perceptions of crime risk. This study uses structural equation modelling to explore the influences on perceptions of safety on public transport and the impact these perceptions have on ridership using a survey sample from Melbourne, Australia. The largest direct influences on feelings of safety on public transport were trust in others and feeling safe in one’s home or on the street at night. Gender and age are commonly-cited influences in the literature but in this model their influence on feelings of safety was indirect. The total indirect effect of age was larger than the indirect effect of gender. Feelings of safety had a small but significant positive influence on how frequently people used public transport. This was slightly smaller than the negative effect of cars in the household but larger than the negative effect of distance from the city centre

Understanding ridership drivers for bus rapid transit systems in Australia

Bus Rapid Transit (BRT) systems are an increasingly popular public transport option in Australia and internationally. They provide rail-like quality for bus services for a fraction of the cost of fixed rail. Many claims of high and increasing ridership have resulted from BRT system development; however it is unclear exactly which aspects of BRT system design drive this.This paper undertakes an empirical analysis of factors influencing ridership on 77 BRT and non-BRT bus routes in Melbourne, Sydney, Adelaide and Brisbane. Explanatory variables considered included service level, frequency, speed, stop spacing, separate right of way share, vehicle accessibility, employment and residential density, car ownership levels and BRT infrastructure quality.The paper reviews previous research associated with transit ridership at a route level and then presents the methodology and results.Two multiple regression analyses were undertaken to explore the influence of the explanatory variables on ridership. The first considers overall ridership (boardings per route km, BRK) and identified a statistically significant model (R2=.81). The largest influence on BRK was vehicle trips per annum (β = .82), consistent with past research, followed by vehicle accessibility (low floor buses, β = .16) and population density (β = .14). The second considered patronage per vehicle kms (PVK) which explores ridership drivers after accounting for service levels. Results for this were statistically significant but with a less powerful model, adjusted R2 = .44. There were four explanatory variables including average speed (β = -.42), weekday frequency (β = .41), BRT infrastructure ranking (β = .29) and vehicle accessibility (β = .25). An alternative form of BRT infrastructure quality was also tested but did not improve the explanatory power of the modelling.The paper concludes with a discussion of the various influences on ridership and recommendations for existing policy and future research associated with this field

Perceptions and Realities of Personal Safety on Public Transport for Young People in Melbourne

This paper aims to explore how perceptions of safety relate to actual experience in the context of urban public transport. It presents the results of an empirical analysis of links between perceptions of personal safety on public transport and compares these with actual experience of travellers. The focus of the work is a survey of young people using public transport in Melbourne Australia.The research literature demonstrates contrasting views with regard to perceptions of personal safety and actual risks. Positive links have been found in some contexts while others have found fears to be unrelated to risk. Some crime surveys and empirical studies suggest perceptions of personal safety are not justified by crime rates. However a series of surveys have shown that those with direct experience of safety incidents have greater concerns with safety. Other research suggests that feelings of anxiety and psychological factors act to make some people feel uncomfortable on public transport and that this acts to increase perceptions of poor personal safety. The paper aims to explore which factors are more important in explaining perceptions of safety.The analysis has identified a series of three statistically significant models which predict personal feelings of safety on public transport using different measures of safety perceptions. In each model psychological influences i.e. „feeling comfortable with people you don‟t know‟ had the biggest individual influence on perceptions of safety with a medium effect size. Gender and the actual experience of a personal safety incident were also found to influence perceptions of personal safety but these variables only had a small effect on perceptions of safety.The paper discusses policy and research implications of the findings including suggestions for future research

Electric cars as a path to sustainable travel behaviour: Insights from Nord-Jæren

This study examines whether promoting electric cars (EVs) to achieve greener mobility undermines the efforts to reduce car use. It specifically explores the concept of moral licensing, wherein individuals use EVs as a way to feel good about their environmental impact while continuing to drive. The study uses travel data (n = 1223) from Nord-Jæren, Norway, to develop a Structural Equation Model (SEM) that explores the relationship between environmental beliefs, attitudes, and travel behaviour (i.e., use of conventional car, electric car, bus, and bicycle). The results confirm that pro-environmental beliefs have a “spillover effect” on EV use due to existing car attitudes. The relative convenience of the car over alternative options has been found to be the most important mitigating factor in the influence of environmental beliefs on behaviour. Consequently, to reduce car use and promote more sustainable travel options, it is essential to simultaneously improve these alternatives while restricting car traffic.publishedVersio

Real-Time Simulation of Indoor Air Flow using the Lattice Boltzmann Method on Graphics Processing Unit

This thesis investigates the usability of the lattice Boltzmann method (LBM) for the simulation of indoor air flows in real-time. It describes the work undertaken during the three years of a Ph.D. study in the School of Mechanical Engineering at the University of Leeds, England. Real-time fluid simulation, i.e. the ability to simulate a virtual system as fast as the real system would evolve, can benefit to many engineering application such as the optimisation of the ventilation system design in data centres or the simulation of pollutant transport in hospitals. And although real-time fluid simulation is an active field of research in computer graphics, these are generally focused on creating visually appealing animation rather than aiming for physical accuracy. The approach taken for this thesis is different as it starts from a physics based model, the lattice Boltzmann method, and takes advantage of the computational power of a graphics processing unit (GPU) to achieve real-time compute capability while maintaining good physical accuracy. The lattice Boltzmann method is reviewed and detailed references are given a variety of models. Particular attention is given to turbulence modelling using the Smagorinsky model in LBM for the simulation of high Reynolds number flow and the coupling of two LBM simulations to simulate thermal flows under the Boussinesq approximation. A detailed analysis of the implementation of the LBM on GPU is conducted. A special attention is given to the optimisation of the algorithm, and the program kernel is shown to achieve a performance of up to 1.5 billion lattice node updates per second, which is found to be sufficient for coarse real-time simulations. Additionally, a review of the real-time visualisation integrated within the program is presented and some of the techniques for automated code generation are introduced. The resulting software is validated against benchmark flows, using their analytical solutions whenever possible, or against other simulation results obtained using accepted method from classical computational fluid dynamics (CFD) either as published in the literature or simulated in-house. The LBM is shown to resolve the flow with similar accuracy and in less time