Statistical bivariate modelling of wind using first-order Markov chain and Weibull distribution

This paper studies the statistical features of the wind at Oran (Algeria). The data used are the wind speed and wind direction measurements collected every 3 h at the meteorological station of Es Senia (Oran), during the 1982/92 period. The eight directions of the compass card have been considered to build the frequency distribution of the wind speed for each month of the year and each direction. The three-hourly wind data have been modelled by means of Markov chains. First-order nine-state Markov chains are found to fit well the wind direction data, whereas the related wind speed data are well fitted by first-order three-state Markov chains. The Weibull probability distribution function has also been considered and found to fit the monthly frequency distributions of wind speed measurements. Two methods of wind data retrieval are thus made available. In fact, two models of chronological bi-series are obtained describing wind speed and wind direction.     

Structure and magnetic properties of nanocrystalline mechanically alloyed Fe–10% Ni and Fe–20% Ni

The mechanical alloying technique has been used to prepare nanocrystalline Fe–10 and Fe–20 wt.% Ni alloys from powder mixtures. The structure and magnetic properties were studied by using X-ray diffraction and hysteresis measurements, respectively. For both alloys studied, a disordered body centered cubic solid solution forms after 24 h milling time. The higher the milling time, the larger the lattice parameter. The steady-state grain size is ≈10 nm. The reduction of the grain size increases the saturation magnetization and decreases the coercivity. Nanocrystalline Fe–10 and Fe–20 wt.% Ni have been shown to exhibit a soft magnetic behavior.     

Buffer and Register Allocation for Memory Space Optimization

In today’s embedded systems, memory hierarchy is rapidly becoming a major factor in terms of power, performance and area. This is especially true for embedded multimedia applications using temporary multi-dimensional arrays that are typically used to store intermediate results during multimedia processing. In this paper, we propose a new technique that optimizes the use of the cache and the registers. It consists in combining buffer and register allocation to reduce the size of the temporary arrays. Firstly we use the concept of live data to replace each array by a buffer of lower size. Then we replace references to these buffers by registers. The buffer allocation step keeps only useful data in memory and the register allocation step allows taking advantage of data reuse in internal loops. Codes considered in this paper are multimedia applications structured as a sequence of loop nests. The experiments are made on Unix environment and on the StepNP simulator (MPSoC platform of STMicroelctronics). They show that our technique yields significant reduction of the number of data cache and TLB misses.

A study on electrodeposited Co–Mo alloys thin films

Cobalt–Molybdenum (Co–Mo) induced electrodeposition has been studied from a sulphate bath on Ru electrodes at pH 4. The conditions of electrodeposition of Co–Mo alloys were determined using the cyclic voltametry at different ions concentration ratios. The theoretical model of Scharifker-Hills was used to analyse the current transients for studying the first stage of nucleation of Co–Mo alloys. The electrodeposited coatings were analysed by scanning electron microscopy, X-rays diffraction and alternating gradient force magnetometer techniques. The cyclic voltametry shows that the codeposition of Co–Mo alloys was accompanied by concurrent reactions such as the formation of the molybdenum oxides and the hydrogen evolution reaction. For the electrodeposited Co–Mo, the nucleation is in good agreement with the instantaneous nucleation and three-dimensional (3D) diffusion-limited growth. Co–Mo thin films of an hcp structure have been obtained, and the electrodeposition parameters such as the applied potential have a great influence on the structure, morphology and magnetic properties.     

Synthesis and Characterization of a Novel Series of Amphiphilic Mercapto-1,2,4-Triazole Schiff Base Ligands: Investigation of their Behavior in Hydro-Organic Solutions

A novel series of four Schiff base amphiphiles derived from 3-mercapto-1,2,4-triazole and different alkyl chains were successfully prepared by a new synthetic three-step method. The chemical structures of the different ligands were characterized by elemental analysis, FT-IR spectroscopy, ¹H-NMR and ¹³C-NMR spectra. The effect of the chain length on the solution behavior of the amphiphilic ligands were studied, in both homogeneous and heterogeneous systems, using pH-metric and spectrophotometric methods. Based on the electronic spectroscopy data, some parameters governing their surfactant properties, such as the critical micelle concentration (CMC), the micellization free energy (ΔG _mic) and the hydrophilic-lipophilic balance (HLB) were evaluated in chloroform and discussed. The behavior of the four Schiff bases in the heterogeneous chloroform-water mixture was then explored through the establishment of their acidity (pK_A) and distribution (Log K _d) constants in 1 M chloride medium and the acidity constants in aqueous medium (pK_a) were deduced. Results showed that an increase of the alkyl chain decreases the distribution of the ligands and increases their acidity. The extractive performance of the Schiff base amphiphiles were investigated towards Ni(II) from a chloride medium at 30 °C. The analysis of extraction data revealed that the synthesized Schiff bases exhibit a better and faster extractability than many ligands reported in the literature.     

Artificial ageing of wood finishes monitored by IR analysis and color measurements

Photocurable finishes appear now as very attractive products for industrial wood joinery for reducing volatile organic compounds (VOC). Nevertheless their poor durability is currently reported. In this study, we aimed to enhance stability of advanced formulations based on photoinitiators working under UV‐visible light by introducing UV absorbers, the absorption band of which is shifted compared to the band of initiators. We tested the efficiency of these stabilizers for two curable coatings applied onto oak and spruce. Modifications of samples at molecular and macroscopic scales were quantified after an accelerated ageing process by FTIR spectroscopy, measurements of color variations, apparition of cracks. It appears that both UV absorbers tested do not greatly improve the durability of systems and the results obtained allow to better understand the causes of the poor characteristics of the finishing systems. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A Model of Grid Service Capacity

Computational grids （CGs） are large scale networks of geographically distributed aggregates of resource clusters that may be contributed by distinct organizations for the provision of computing services such as model simulation, compute cycle and data mining. Traditionally, the decision-making strategies underlying the grid management mechanisms rely on the physical view of the grid resource model. This entails the need for complex multi-dimensional search strategies and a considerable level of resource state information exchange between the grid management domains. In this paper we argue that with the adoption of service oriented grid architectures, a logical service-oriented view of the resource model provides a more appropriate level of abstraction to express the grid capacity to handle incoming service requests. In this respect, we propose a quantification model of the aggregated service capacity of the hosting environment that is updated based on the monitored state of the various environmental resources required by the hosted services. A comparative experimental validation of the model shows its performance towards enabling an adequate exploitation of provisioned services.     

Reverse engineering relational databases to identify and specify basic Web services with respect to service oriented computing

Service-oriented computing (SOC) is the computing paradigm that utilizes services as a fundamental building block. Services are self-describing, open components intended to support composition of distributed applications. Currently, Web services provide a standard-based realization of SOC due to: (1) the machine-readable format (XML) of their functional and nonfunctional specifications, and (2) their messaging protocols built on top of the Internet. However, how to methodologically identify, specify, design, deploy and manage a sound and complete set of Web services to move to a service-oriented architecture (SOA) is still an issue. This paper describes a process for reverse engineering relational database applications architecture into SOA architecture, where SQL statements are insulated from the applications, factored, implemented, and registered as Web services to be discovered, selected, and reused in composing e-business solutions. The process is based on two types of design patterns: schema transformation pattern and CRUD operations pattern. First, the schema transformation pattern allows an identification of the services. Then the CRUD operations pattern allows a specification of the abstract part of the identified services, namely their port types. This process is implemented as a CASE tool, which assists analysts specifying services that implement common, reusable, basic business logic and data manipulation.