Enhanced photoelectrochemical water splitting via engineered surface defects of BiPO4 nanorod photoanodes

Herein, we report on the defect engineering of BiPO₄ nanorods (NRs) via a facile room-temperature template-free co-precipitation method, followed by hydrogen treatment. The hydrogen treatment temperature determined the type of induced defects in the fabricated BiPO₄ NRs and consequently their photocatalytic performance. Upon varying the annealing temperature, the x-ray diffraction (XRD) analysis showed phase transformation and x-ray photoelectron spectroscopy (XPS) analysis revealed variation in the oxygen vacancy content. At moderate treatment temperatures (200–300 °C), shallow defects were predominant, which extended the optical activity of the material to the visible region and increased the photocurrent 3 times when compared to that of bare BiPO₄ NRs. However, treatment at higher temperatures completely altered the crystalline structure, destructed the morphology of the BiPO₄ NRs, and severely affected the photoelectrochemical performance.     

Computational estimation of ESD conditions between a charged bodyand a conductor of floating potential

This paper examines the conditions in which a discharge occurs between a charged body and a floating conductor, in air, at atmospheric pressure. The study, which was primarily aimed at simulating a class of hazardous situations quite often met in the operation of electronic circuits, is also of interest to those involved in the research and development of electrostatic technologies for processing of particulate matter: separation of granular mixtures, precipitation of dust, and spraying of powders. The boundary-element method was employed for the analysis of the electric field in the gap between the charged body and the conductive disk at floating potential, located above a grounded plate. The computations were carried out for bodies of various shapes and sizes; some of them addressed the case of a grounded plate covered with an insulating layer of known permittivity. The data on field distribution represented the input data of another program, which estimated the breakdown conditions of that air gap. The study enabled the estimation of the energy involved in this type of electrostatic discharge and the prediction of the related hazards     

Bending of cross-ply laminated plates resting on elastic foundations under thermo-mechanical loading

This article investigates the bending response of an orthotropic rectangular plate resting on two-parameter elastic foundations under thermo-mechanical loadings. Analytical solutions for deflection and stresses are investigated by using an unified shear deformation plate theory. The present plate theory enables the trial and testing of different through-the-thickness transverse shear-deformation distributions and, among them, strain distributions that do not involve the undesirable implications of the transverse shear correction factors. The governing equations that include the interaction between the plate and the foundations are obtained. Numerical results are presented to demonstrate the behavior of the system. The influences of aspect ratio, side-to-thickness ratio, thermal expansion coefficients ratio and stacking sequence on the thermally induced response are studied.     

Bending analysis of FG viscoelastic sandwich beams with elastic cores resting on Pasternak’s elastic foundations

The investigation of bending response of a simply supported functionally graded (FG) viscoelastic sandwich beam with elastic core resting on Pasternak’s elastic foundations is presented. The faces of the sandwich beam are made of FG viscoelastic material while the core is still elastic. Material properties are graded from the elastic interfaces through the viscoelastic faces of the beam. The elastic parameters of the faces are considered to be varying according to a power-law distribution in terms of the volume fraction of the constituent. The interaction between the beam and the foundations is included in the formulation. Numerical results for deflections and stresses obtained using the refined sinusoidal shear deformation beam theory are compared with those obtained using the simple sinusoidal shear deformation beam theory, higher- and first-order shear deformation beam theories. The effects due to material distribution, span-to-thickness ratio, foundation stiffness and time parameter on the deflection and stresses are investigated.     

Modeling and simulation of an electronic component manufacturingsystem using hybrid Petri nets

Modelling and analysis for the design and operation of manufacturing systems is a vital need. For semiconductor manufacturing systems, which are large scale systems, discrete Petri nets do not constitute an adequate tool for modeling and analysis. In fact, use of discrete Petri nets is confronted with tile state explosion and the high cost of simulation. In this paper, hybrid Petri nets are presented as powerful tools for modeling and simulation of semiconductor manufacturing systems. This model has been used for modeling and simulation of a real life electronic components manufacturing system. It provides an accurate and first simulation of this system     

Novel cyclostationarity-based blind source separation algorithm using second order statistical properties: Theory and application to the bearing defect diagnosis

Among signal processing techniques, blind source separation (BSS) and the underlying mathematical tool of independent component analysis (ICA) are of continuously growing interest in the scientific community of various research domains. Vibration analysis is a potential application field of this quite recent technique.Actually, BSS methods aim to retrieve unknown source signals from a set of their observations coming to a matrix of sensors, without necessarily having any prior knowledge about the sources. In monitoring and diagnosis purposes, bearing defects constitute a problem for manufacturers who aim at predicting those faults as well as potential engines breakdowns. These defects may be the unknown sources one wants to estimate from a set of recorded signals by a matrix of accelerometers placed close to the rotating machine.It has been shown that these vibration signals are wide-sense cyclostationary [[11] R.B.Randall, J. Antoni, S. Chobsaard, The relationship between spectral correlation and envelope analysis in the diagnostics of bearing faults and other cyclostationary machine signals, Mechanical Systems and Signal Processing 15 (5) (2001) 945–962]. The new algorithm of BSS proposed in this work is based, precisely, on that property. Second-order statistics of such processes led us to a new separation criterion for blind source separation. The theoretical results of this study, simulation and experimental analysis are presented in here. Perspectives for future research conclude this paper.     

Nickel‐Catalyzed C?S Bond Formation: Synthesis of Aryl Sulfides from Arylsulfonyl Hydrazides and Boronic Acids

A practical nickel‐catalysed approach has been developed for the C S bond formation through the cross‐coupling of arylsulfonyl hydrazides and aryl boronic acids. The report employs arylsulfonyl hydrazide as an aryl thiol equivalent and offers a mild and eco‐safe synthesis of unsymmetrical thioethers in good to excellent yields in air. The scope and versatility of the method has been successfully demonstrated with 22 examples.

     

New high-Q discrete-time LC bandpass filter design with center frequency broadband tuning

Discrete-time switched-capacitor filters have been in wide-spread used for a few years, for the realization of stable, accurate and high quality filters. This paper describes the design of a new 8-path pseudo switched-capacitor LC bandpass filter and its command circuit made up by a ring voltage controlled oscillator (VCO) with ‘XOR’ gates. The proposed architecture presents the possibility of tuning over a frequency broadband allowing to sweep different channels with a high quality factor. This circuit is intended to replace the surface acoustic wave (SAW) filters in broadband wireless applications. Experimental results carried out on a prototype show quality factors up to 200, and a tunable center frequency range of 300 MHz [250–550 MHz]. Ahmed El Oualkadi received the PhD. degree in electronics from the University of Poitiers, France, in 2004. Since 2001, he has been with the LAII-ESIP laboratory, Electronics & Electrostatics Research Unit, University of Poitiers, France. In 2004, he was an assistant lecturer of Electronics Engineering at the University Institute of Technology, Angoulême, France. During this period he worked on various projects which concern the nonlinear analysis & design of switched-capacitor filters for radio-communication systems. Currently, he is a senior research engineer at the Université Catholique de Louvain, Microelectronics Laboratory, Louvain-la-Neuve, Belgium. His main interest of research is the design of low power high temperature circuits and systems for low cost wireless communications especially for ZigBee applications. Jean-Marie Paillot received a Ph.D in Electronics form the University of Limoges, in 1990. His thesis on the design of non-linear analog circuits and the study of the noise spectral of integrated oscillators was prepared at the Institute of Research for Optical Communications and Microwaves, Limoges. After graduation, he joined the Electronics Laboratory of PHILIPS Microwave, at Limeil, as R&D engineer in charge of the design of analogical and numerical microwave monolithic integrated circuits. Since October 1992, J.M. Paillot is at the University Institute of Technology, Angoulême, where he currently is Professor of Electronics Engineering. In charge of several contracts with industry, and author of papers published in scientific journals, J.M. Paillot is at present interested in phase noise reduction techniques for microwave oscillators, as well as in the research and development of switched capacitor filters in RF domain. Rachid Allam received the Dipl. Eng. Degree from the Université des Sciences et Technologies dran, Algeria, in 1980. He joined the Centre Hyperfréquences et Semiconducteurs, University of Lille 1,Villeneuve d’Ascq, France, in 1980. He received the Docteur-Ingénieur degree in 1984 from the University of Lille 1. In 1988, he joined the Institut d’Electronique et de Microélectronique du Nord and received the Habilitation à Diriger les Recherches en Sciences Physiques degree, in 1996. Currently, he is Assistant Professor at the University of Poitiers (IUT Angoulême), France. In 1997, he joined the Equipe Electronique et Electrostatique at the Laboratoire d’Automatique et d’Informatique Industrielle (LAII - UPRESS - EA 1219). Research work concerns microwaves devices and circuits, FET nonlinear modeling, microwaves mixers, non linear CAD, millimeter wave MMIC’s and non linear noise analysis.     

Effect of New Nag Hammadi Barrage on Groundwater and Drainage Conditions and Suggestion of Mitigation Measures

The government of Egypt has decided to construct a new barrage with hydropower facilities, 3.5 km downstream of the existing old one. The water levels in the head pond for the new barrage will be continuously maintained at a level with approximately 0.5 m higher than water level in the head pond of the existing one. To evaluate the effect of increasing the head pond water level on the groundwater and drainage, there is a need to enhancelinking reservoir and stream/aquifer system. Visual MODFLOW hasbeen used to simulate the surface water/groundwater interaction in the area of proposed new barrage. The model has been calibratedagainst the available historical groundwater levels for 25 observation wells based on the steady state conditions. Numerical modeling suggests that river stage is the primary control of rapid groundwater hydraulic head fluctuations in theaquifer system. At present the area at which the depth to groundwater table less than one meter is about 30 110 feddans (1 feddan = 4200 m²). This area will increase to be about40 610 feddans after the construction of the new barrage and increasing the head pond water level. The mitigation measures toovercome the effect of construction of the new barrage have been discussed and their costs have been estimated and evaluated. Increasing the efficiency of existing drainage system by maintenance/upgrading and constructing a new pump station is recommended.