L'enjeux des evaluations internationales

A co-authored article about international programmes of student assessment (PIS, TIMSS) that sets the context for other articles that follow in a volume edited by the co-authors

Elastic-plastic analysis of pressure vessels and rotating disks made of functionally graded materials using the isogeometric approach

An NURBS-based isogeometric analysis for elastic-plastic stress in a cylindrical pressure vessel is presented. The vessel is made of a ceramic/metal functionally graded material, i.e. a particle-reinforced composite. It is assumed that the material plastic deformation follows an isotropic strain-hardening rule based on the von Mises yield criterion. The mechanical properties of the graded material are modelled by the modified rule of mixtures. Selected finite element results are also presented to establish the supporting evidence for validation of the isogeometric analysis. Similar analyses are performed and solutions for spherical pressure vessel and rotating disk made of FGMs are also provided

Analyzing the Consequences of Bad Outsourcing on Human Resources in Iranian Public Organizations

The purpose of present research is to compare the status of perceptional and behavioral consequences on employees who serve in bad-outsourced departments of one of Iranian public organizations and the status of consequences on those employees who serve in non-outsourced departments of the same organization. In this line, such variables as organizational justice, organizational commitment, organizational identity, job security and anti-citizenship behaviors are compared between two groups of staff. The findings show that the rate of organizational justice, organizational commitment, organizational identity and job security among those employees who serve in bad-outsourced sectors is lower than similar variables among non-outsourced ones. In the meantime, there is no significant difference between groups in terms of anticitizenship behaviors variable. Noteworthy, present study was conducted in summer and fall 2010 in Iran

Multifunctional layered double hydroxide (LDH) based epoxy nanocomposites

As one of the most important thermosetting polymers, epoxy resin (EP) has acquired wide application in the fields of coating, adhesive, electronic/electrical insulation, carbon fiber composites and etc. EP possesses many outstanding advantages, such as low shrinkage, high thermal and mechanical stabilities and excellent solvent and chemical resistance. However, like most of polymeric materials, high flammability of EP is its main fatal drawback, which has severely restricted the application fields required a remarkable flame-retardant standards. Thus, the flame retardancy of epoxy resins continues to remain as a very important area of research for polymer chemists and material engineers. Such research is also highly encouraged by the polymer industries because of huge economic and sociological casualties involved each year in fire accidents. Among the various methods of improving flame retardancy of polymeric materials, incorporation of flame retardants is a very commonly used one. The present work and the relevant reporting involve the investigation of a relatively new fascinating nano-filler, known as layered double hydroxide (LDH) as potential flame retardant for polymers composites. The basic reason for selecting LDH or more specifically magnesium-aluminum based LDH (Mg-Al–LDH) is their typical metal hydroxide-like chemistry and conventional clay-like layered crystalline structure. The current dissertation containing: •Functionalization of LDH; Multi-modifiers’ systems composed by bio-based modifiers such as hydroxypropyl-sulfobutyl-beta-cyclodextrin sodium (sCD) and its hybridized form with chalcone species (fCD), taurine (T), phytic acid (Ph), and dodecylbenzenesulfonate (DBS) were fabricated in this thesis, each designed for specified feature, aiming at developing high performance fire retardant epoxy nanocomposites. •Preparation and characterization of functionalized LDH based epoxy nanocomposites; Based on these functionalized LDHs, bisphenol A epoxy resin and diamino diphenyl sulfone (DDS), and utilizing multi step mixing method followed by appropriate curing process, series functionalized LDH/Epoxy nanocomposites have been developed. •Structural Properties relationship; The structural morphology of LDH/epoxy nanocomposites was investigated by transmission electron microscopy (TEM) and wide-angle X-ray scattering (WAXS), revealing that multi-modified LDH based epoxy nanocomposites showed much better dispersion state than the epoxy composites containing un-modified LDH or single modifier modified LDH. In contrast to conventional LDHs based epoxy composites, the functionalized LDH based epoxy nanocomposites show significantly improvement on both flame retardancy, such as passing UL94 V0 rating and significant reduction of peak of heat release rate, total heat release, total smoke, etc. and well maintenance on impact, flexural, micro-mechanical and anti-UV properties. Such multifunctional nano-hybrid will provide a promising solution to develop various functional epoxy-based composites for advanced applications.Como uno de los polímeros termoestables más importantes, resina epoxi (EP) ha adquirido una amplia aplicación en los campos de recubrimiento, adhesivos, aislamiento eléctrico / electrónico, materiales compuestos de fibra de carbono y etc. EP posee muchas ventajas excepcionales, tales como baja contracción, alta térmica y estabilidades mecánicas y excelente disolvente y resistencia química. Sin embargo, como la mayoría de los materiales poliméricos, alta inflamabilidad de EP es su principal inconveniente fatal, que ha restringido severamente la aplicación campos requieren un notable estándares ignífugos. Por lo tanto, la resistencia a la llama de resinas epoxi sigue siendo como un área muy importante de la investigación para los químicos de polímeros e ingenieros de materiales. Este tipo de investigación es también muy animado por las industrias de polímeros debido a enormes bajas económicas y sociológicas que participan cada año en accidentes de fuego. Entre los diversos métodos para mejorar llama retardancia de materiales poliméricos, la incorporación de los retardantes de la llama es muy comúnmente usada. El presente trabajo y el informe correspondiente implican la investigación de un nuevo y fascinante nano-relleno relativamente, conocido como de doble capa de hidróxido (LDH) como potencial retardante de llama para polímeros compuestos. La razón básica para la selección de LDH o LDH más basada en específicamente de magnesio-aluminio (Mg-Al-LDH) es su química típica hidróxido como el metal y la estructura cristalina capas similar a la arcilla convencional. La tesis actual que contiene: • La funcionalización de la LDH; Los sistemas Multi-modificadores 'compuestas por modificadores de origen biológico, tales como hidroxipropil-sulfobutil-beta-ciclodextrina de sodio (SCD) y su forma hibridado con especies chalcona (FCD), taurina (T), el ácido fítico (Ph) y dodecilbencenosulfonato (DBS ) fueron fabricados en esta tesis, cada uno diseñado para la función especificada, con el objetivo de desarrollar de alto rendimiento nanocompuestos epoxi retardante de fuego. • Preparación y caracterización de nanocompuestos epoxi funcionalizados LDH basada; En base a estos LDHs funcionalizados, sulfona de bisfenol A resina epoxi y diamino difenil (DDS), y utilizando el método de mezclado de múltiples fases seguido por el proceso de curado apropiado, se han desarrollado series funcionalizado nanocompuestos LDH / epoxi. • Relación Propiedades Estructurales; La morfología estructural de nanocompuestos de LDH / epoxi se investigó por microscopía electrónica de transmisión (TEM) y de amplio ángulo de dispersión de rayos X (WAXS), revelando que LDH basado nanocompuestos epoxi multi-modificado mostraron mucho mejor estado de dispersión de los materiales compuestos epoxi que contienen ONU LDH modificado o solo LDH modificado modificador. En contraste con los materiales compuestos epoxi basadas LDHs convencionales, los nanocompuestos de LDH epoxi basada funcionalizados muestran una mejora significativa tanto en resistencia a la llama, tales como pasar calificación V0 UL94 y una reducción significativa del pico de la tasa de liberación de calor, la liberación total de calor, el humo total, etc. y bien el mantenimiento de las propiedades de impacto, flexión, micro-mecánicos y anti-UV. Tal multifuncional nano-híbrido proporcionará una solución prometedora para desarrollar diversos materiales compuestos a base de epoxi funcionales para aplicaciones avanzadas.Financial support for the work described in this dissertation by EU 7th Framework Programme through the project ECOFIRE-NANO (reference: 321951).Programa de Doctorado en Ciencia e Ingeniería de MaterialesPresidente: Juan Baselga Llidó.- Secretario: Santiago Gómez Ruiz.- Vocal: Carlos Daniel Gonzales Martíne

ON THE EFFECT OF USING CUBIC BOXES ON VOCABULARY ACQUISITION OF EFL YOUNG LEARNERS

Vocabulary acquisition has long been a major concern among EFL instructors teaching young learners. Among all the techniques proposed for vocabulary retention and enhancement among young learners, using cubic boxes can play a pivotal role in developing and activating young learners to acquire elementary vocabularies more effectively. It was proven in this study that cooperative vocabulary activities among those young leaners applying cubic boxes outweighs the ones who try to acquire new words via traditional pen-and-paper techniques. Thus, using cubic boxes possesses a major function in vocabulary enhancement and retention of young learners of English. Moreover, vocabulary learning based on the adaptation of the cubic boxes is highly cooperative and leads to more dynamic learning rather than individual vocabulary learning in language classrooms.  Article visualizations

Key Elements of Thinking Strategically

Strategic thinking is one of the most important capabilities which managers of today’s organizations must possess. Holding companies, due to the kind of problems that they experience, are in serious need of managers capable of strategic thinking. The present research has been conducted with the aim of identifying the individual dimensions of strategic thinking in holding companies’ managers in Iran. In this regard, a number of managers who have had the experience of being members of the board of directors or working as CEOs of these firms have been asked to express their opinions about strategic thinking and their views have been analyzed using fuzzy cognitive maps. Results suggest that having vision, ability to analyze, having systems thinking, ability to question, creativity, ability to make synergy and ability to create advantage are the main elements of strategic thinking in successful managers of holding companies. In addition, the relationships among these variables have been explained

Interferometric investigation of the opto-mechanical and structural properties of iPP/TiO2 nanocomposite fibers

Fibers that missing specific features and functionalities could be innovated and functionalised via nano additives, in particular metal oxides. Titanium oxide (TiO2) nanoparticles have been added to isotactic polypropylene (iPP) to form iPP/TiO2 nanocomposite fibers. Three samples of iPP/TiO2 fibers were extruded at three extrusion speeds 25, 50, and 78 m/min were considered in this study. Mach–Zehnder interferometer was used to assess the changes in the opto‐mechanical and geometrical parameters of iPP/TiO2 nanocomposite fibers along the fiber axis. The mechanical drawing device along with Mach–Zehnder interferometer was utilized to stretch the filaments to different draw ratios. The effect of mechanical cold drawing and extrusion speed on the optical and physical characteristics of iPP/TiO2 nanocomposite fibers were determined along the fiber axis. The optical and physical variation along the nanocomposite samples were characterized by measuring their refractive indices, birefringence, refractive index profile along the fiber axis. The diffraction of He–Ne laser beam was used to define the variation of the fiber diameter along the fiber axis through their cross‐sectional area and shape. A sample of uniform diameter from neat iPP fibers was used as reference material for studying the variation of the iPP/TiO2 fiber diameter along the fiber axis. As result, the iPP/TiO2 nanocomposite fibers exhibited nonuniform diameters. The dispersion of TiO2 particles in nanocomposite fibers influences the properties' consistency along and across the fiber

Novel approximate absolute difference hardware

Approximate hardware designs have higher performance, smaller area or lower power consumption than exact hardware designs at the expense of lower accuracy. Absolute difference (AD) operation is heavily used in many applications such as motion estimation (ME) for video compression, ME for frame rate conversion, stereo matching for depth estimation. Since most of the applications using AD operation are error tolerant by their nature, approximate hardware designs can be used in these applications. In this paper, novel approximate AD hardware designs are proposed. The proposed approximate AD hardware implementations have higher performance, smaller area and lower power consumption than exact AD hardware implementations at the expense of lower accuracy. They also have less error, smaller area and lower power consumption than the approximate AD hardware implementations which use approximate adders proposed in the literature

FPGA implementation of HEVC intra prediction using high-level synthesis

Intra prediction algorithm in the recently developed High Efficiency Video Coding (HEVC) standard has very high computational complexity. High-level synthesis (HLS) tools are started to be successfully used for FPGA implementations of digital signal processing algorithms. Therefore, in this paper, the first FPGA implementation of HEVC intra prediction algorithm using a HLS tool in the literature is proposed. The proposed HEVC intra prediction hardware, in the worst case, can process 35 full HD (1920×1080) video frames per second. Using HLS tool significantly reduced the FPGA development time. Therefore, HLS tools can be used for FPGA implementation of HEVC video encoder