Foldings and grazings of tori in current controlled interleaved boost converters

Interleaved boost converters (IBCs) are used when energy conversion is required at high current levels. Such converter systems may undergo various nonlinear phenomena which can affect their performance adversely. In this paper, we study an IBC and demonstrate the first instability through a Neimark–Sacker bifurcation, resulting in a torus. An analysis based on the calculation of the monodromy matrix reveals that the torus has a rather strange form as the complex Floquet multipliers that became unstable have a real value close to ?1. We show that further variation in a parameter can result in novel nonlinear phenomena where the torus itself folds and grazes a switching manifold, resulting in a ‘wobbling’ of the closed loop that represents the torus in discrete time. Numerical and analytical results validate our work. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of Al doping and deposition runs on structural and optical properties of In<Subscript>2</Subscript>S<Subscript>3</Subscript> thin films grown by CBD

β-In_2−x Al _x S₃ thin films have been grown on glass substrate by chemical bath deposition for different value of Al concentration y = (([Al])/([In]))_sol (0 ≤ y ≤ 5 at.%). Samples have been characterized using X-ray diffraction, atomic force microscopy and by spectrophotometric measurements. The influence of the increase of y ratio in the structural and optical properties are described and discussed in terms of crystallinity improvement. In order to increase film thickness of β-In_2−x Al _x S₃, we have been realized multi-deposition system. The structural, the surface morphology as well as the optical properties seem to be improved as the film thickness is of about 1200 nm.     

Determining the causal relationships among balanced scorecard perspectives on school safety performance: Case of Saudi Arabia

In the public schools of many developing countries, numerous accidents and incidents occur because of poor safety regulations and management systems. To improve the educational environment in Saudi Arabia, the Ministry of Education seeks novel approaches to measure school safety performance in order to decrease incidents and accidents. The main objective of this research was to develop a systematic approach for measuring Saudi school safety performance using the balanced scorecard framework philosophy. The evolved third generation balanced scorecard framework is considered to be a suitable and robust framework that captures the system-wide leading and lagging indicators of business performance. The balanced scorecard architecture is ideal for adaptation to complex areas such as safety management where a holistic system evaluation is more effective than traditional compartmentalised approaches. In developing the safety performance balanced scorecard for Saudi schools, the conceptual framework was first developed and peer-reviewed by eighteen Saudi education experts. Next, 200 participants, including teachers, school executives, and Ministry of Education officers, were recruited to rate both the importance and the performance of 79 measurement items used in the framework. Exploratory factor analysis, followed by the confirmatory partial least squares method, was then conducted in order to operationalise the safety performance balanced scorecard, which encapsulates the following five salient perspectives: safety management and leadership; safety learning and training; safety policy, procedures and processes; workforce safety culture; and safety performance. Partial least squares based structural equation modelling was then conducted to reveal five significant relationships between perspectives, namely, safety management and leadership had a significant effect on safety learning and training and safety policy, procedures and processes, both safety learning and training and safety policy, procedures and processes had significant effects on workforce safety culture, and workforce safety culture had a significant effect on safety performance.     

An Optimized SW/HW AVMF Design Based on High-Level Synthesis Flow for Color Images

In this paper, a software/hardware High-level Synthesis (HLS) design is proposed to compute the Adaptive Vector Median Filter (AVMF) in real-time. In fact, this filter is known by its excellent impulsive noise suppression and chromaticity conservation. The software (SW) study of this filter demonstrates that its implementation is too complex. The purpose of this work is to study the impact of using an HLS tool to design ideal floating-point and optimized fixed-point hardware (HW) architectures for the AVMF filter using square root function (ideal HW) and ROM memory (optimized HW), respectively, to select the best HLS architectures and to design an efficient HLS software/hardware (SW/HW) embedded AVMF design to achieve a trade-off between the processing time, power consumption and hardware cost. For that purpose, some approximations using ROM memory were proposed to perform the square root and develop a fixed-point AVMF algorithm. After that, the best solution generated for each HLS design was integrated in the SW/HW environment and evaluated under ZC702 FPGA platform. The experimental results showed a reduction of about 65% and 98% in both the power consumption and processing time for the ideal SW/HW implementation relative to the ideal SW implementation for an AVMF filter with the same image quality, respectively. Moreover, the power consumption and processing time of the optimized SW/HW are 70% and 97% less than the optimized SW implementation, respectively. In addition, the Look Up Table (LUTs) percentage, power consumption and processing time used by the optimized SW/HW design are improved by nearly 45%, 18% and 61% compared the ideal SW/HW design, respectively, with slight decrease in the image quality.     

Trace elements‐based Auroshell gold@hematite nanostructure: Green synthesis and their hyperthermia therapy

Hyperthermia is an additional treatment method to radiation therapy/chemotherapy, which increases the survival rate of patients without side effects. Nowadays, Auroshell nanoparticles have attracted much attention due to their precise control over heat use for medical purposes. In this research, iron/gold Auroshell nanoparticles were synthesised using green nanotechnology approach. Auroshell gold@hematite nanoparticles were synthesised and characterised with rosemary extract in one step and the green synthesised nanoparticles were characterised by X‐ray powder diffraction, SEM, high‐resolution transmission electron microscopy, and X‐ray photoelectron spectroscopy analysis. Cytotoxicity of Auroshell iron@gold nanoparticles against normal HUVEC cells and glioblastoma cancer cells was evaluated by 2,5‐diphenyl‐2H‐tetrazolium bromide method, water bath hyperthermia, and combined method of water bath hyperthermia and nano‐therapy. Auroshell gold@hematite nanoparticles with minimal toxicity are safe against normal cells. The gold shell around the magnetic core of magnetite caused the environmental and cellular biocompatibility of these Auroshell nanoparticles. These magnetic nanoparticles with targeted control and transfer to the tumour tissue led to uniform heating of malignant tumours as the most efficient therapeutic agent.     

Interpolation functions in control volume finite element method

 The main contribution of this paper is the study of interpolation functions in control volume finite element method used in equal order and applied to an incompressible two-dimensional fluid flow. Especially, the exponential interpolation function expressed in the elemental local coordinate system is compared to the classic linear interpolation function expressed in the global coordinate system. A quantitative comparison is achieved by the application of these two schemes to four flows that we know the analytical solutions. These flows are classified in two groups: flows with privileged direction and flows without. The two interpolation functions are applied to a triangular element of the domain then; a direct comparison of the results given by each interpolation function to the exact value is easily realized. The two functions are also compared when used to solve the discretized equations over the entire domain. Stability of the numerical process and accuracy of solutions are compared. Received: 20 October 2002 / Accepted: 2 December 2002     

Fabrication of tissue engineering scaffold from poly(vinylalcohol-co-ethylene)/poly(D,L-lactic-co-glycolic acid) blend: Miscibility,thermomechanical properties,and morphology

A series of poly(DL-lactide-co-glycolic acid) (PLGA) with poly(vinylalcohol-co-ethylene) (PEVAL) blends were prepared by solution casting method. The miscibility, thermal and mechanical properties have been investigated using FTIR, DSC, and DMA techniques. The miscibility of this pair of polymers throughout compositions was proved by these methods through the single T_g and the presence of interactions between the constituents. The TGA analysis revealed three degradation zones and no sensible enhancement in the thermal stability of PLGA was noted with addition of PEVAL content. The SEM analysis revealed that the draying method dramatically influence the surface morphology of copolymers and blend. The cross section micrograph of blend scaffold containing 50 wt% of PEVAL presents microcavities of diameter pores ranged between 70 and 170 µm interconnected and uniformly distributed in the polymer matrix.     

Ethanol electrooxidation on activated graphite supported platinum-nickel in alkaline medium

In this study, activated graphite-supported platinum (Pt/C), nickel (Ni/C) and platinum-nickel (Pt–Ni/C) were prepared by electrodeposition technique using solutions containing hexachloroplatinic acid and/or nickel sulphate. Ethanol electrooxidation was investigated on Pt/C, Ni/C and Pt–Ni/C electrocatalysts by cyclic voltammetry and chronoamperometry in aqueous alkaline solution containing 1.0 M NaOH and 2.0 M C₂H₅OH. The electrocatalytic activities and stabilities of the electrocatalysts were discussed. The results showed that ethanol is oxidized anodically on Ni/C. This reaction occured simultaneously with the anodic oxidation of nickel hydroxide (Ni(OH)₂) into nickel oxy-hydroxide (NiOOH). It is also found that Pt–Ni/C electrocatalytic characteristics were better than Pt/C. The Pt–Ni/C electrocatalyst exhibited excellent activity and enhanced stability than Pt/C. It seems that Pt–Ni/C is a promising electrocatalyst toward ethanol electrooxidation in alkaline medium for fuel cells applications.     

A voltammetric electronic tongue as tool for water quality monitoring in wastewater treatment plants

The use of a voltammetric electronic tongue as tool for the prediction of concentration levels of certain water quality parameters from influent and effluent wastewater from a Submerged Anaerobic Membrane Bioreactor pilot plant applied to domestic wastewater treatment is proposed here. The electronic tongue consists of a set of noble (Au, Pt, Rh, Ir, and Ag) and non-noble (Ni, Co and Cu) electrodes that were housed inside a stainless steel cylinder which was used as the body of the electronic tongue system. As a previous step an electrochemical study of the response of the ions sulphate, orthophosphate, acetate, bicarbonate and ammonium was carried out in water using the electrodes contained in the electronic tongue. The second part of the work was devoted to the application of the electronic tongue to the characterization of the influent and effluent waters from the wastewater treatment plant. Partial Least Squares analysis was used to obtain a correlation between the data from the tongue and the pollution parameters measured in the laboratory such as soluble chemical oxygen demand (CODs), soluble biological oxygen demand (BODs), ammonia (NH₄-N), orthophosphate (PO₄-P), Sulphate (SO₄-S), acetic acid (HAC) and alkalinity (Alk). A total of 28 and 11 samples were used in the training and the validation steps, respectively, for both influent and effluent water samples. The electronic tongue showed relatively good predictive power for the determination of BOD, COD, NH₄-N, PO₄-P, SO₄-S, and Alk.     

Postnatal Protein Intake as a Determinant of Skeletal Muscle Structure and Function in Mice—A Pilot Study

Sarcopenia is characterised by an age-related decrease in the number of muscle fibres and additional weakening of the remaining fibres, resulting in a reduction in muscle mass and function. Many studies associate poor maternal nutrition during gestation and/or lactation with altered skeletal muscle homeostasis in the offspring and the development of sarcopenia. The aim of this study was to determine whether the musculoskeletal physiology in offspring born to mouse dams fed a low-protein diet during pregnancy was altered and whether any physiological changes could be modulated by the nutritional protein content in early postnatal stages. Thy1-YFP female mice were fed ad libitum on either a normal (20%) or a low-protein (5%) diet. Newborn pups were cross-fostered to different lactating dams (maintained on a 20% or 5% diet) to generate three groups analysed at weaning (21 days): Normal-to-Normal (NN), Normal-to-Low (NL) and Low-to-Normal (LN). Further offspring were maintained ad libitum on the same diet as during lactation until 12 weeks of age, creating another three groups (NNN, NLL, LNN). Mice on a low protein diet postnatally (NL, NLL) exhibited a significant reduction in body and muscle weight persisting up to 12 weeks, unlike mice on a low protein diet only prenatally (LN, LNN). Muscle fibre size was reduced in mice from the NL but not LN group, showing recovery at 12 weeks of age. Muscle force was reduced in NLL mice, concomitant with changes in the NMJ site and changes in atrophy-related and myosin genes. In addition, μCT scans of mouse tibiae at 12 weeks of age revealed changes in bone mass and morphology, resulting in a higher bone mass in the NLL group than the control NNN group. Finally, changes in the expression of miR-133 in the muscle of NLL mice suggest a regulatory role for this microRNA in muscle development in response to postnatal diet changes. Overall, this data shows that a low maternal protein diet and early postnatal life low-protein intake in mice can impact skeletal muscle physiology and function in early life while postnatal low protein diet favours bone integrity in adulthood.