Desenvolvimento e caracterização de compósito processados por RTM para aplicação aeroespacial

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Test of a mediation model of perceived organisational support

This study examined the mediating influence of trust in organization (TIO) and organization-based self-esteem (OBSE) on the relationship between perceived organization support (POS) and its work outcomes. Data were obtained from employee–supervisor dyads from multiple organizations located in a major city in southern China. Structural equation modeling results revealed that: (a) POS related to TIO and OBSE and (b) TIO and OBSE fully mediated the relationship between POS and the work outcomes of organizational commitment and in-role performance, but partially mediated the POS–organizational citizenship behavior relationship.

Infant wrapping as an evidence-based strategy to encourage settling and the utilisation of the supine sleep position

Objective: To identify knowledge, attitudes and practices of child health nurses relating to infant wrapping as an effective settling/sleep strategy. Methods: A pre-test/post-test intervention design was used to explore knowledge, attitudes and practices relating to wrapping in a sample of child health nurses (n=182): a) pre-test survey; b) educational intervention incorporating evidence relating to infant wrapping; SIDS&KIDS endorsed infant wrapping pamphlet; Safe Sleeping recommendations. Emphasis was placed on infant wrapping as an effective settling strategy for parents to use as an alternative to prone positioning; c) post-test survey to evaluate intervention effectiveness. Results: Pretest results identified wide variation in nurses’ knowledge, attitudes and practices of infant wrapping as a settling/sleep strategy. The intervention increased awareness of wrapping guidelines and self-reported practices relating to parent advice. Significant positive changes in nurses’ awareness of wrapping guidelines (p<0.001); to wrap in supine position only (p<0.001); and parental advice to use wrapping as an alternative strategy to prone positioning to assist settling/sleep (p<0.01), were achieved post-test. Conclusions: Managing unsettled infants and promoting safe sleeping practices are issues routinely addressed by child health nurses working with parents of young infants. Queensland has a high incidence of prone sleeping. Infant wrapping is an evidence-based strategy to improve settling and promote supine sleep consistent with public health recommendations. Infant wrapping guidelines are now included in Queensland Health’s state policy and Australian SIDSandKids information relating to safe infant sleeping. In communicating complex health messages to parents, health professionals have a key role in reinforcing safe sleeping recommendations and offering safe, effective settling/sleep strategies to address the non-recommended use of prone positioning for unsettled infants.

Reactive image-based collision avoidance system for unmanned aircraft systems

Approximately 20 years have passed now since the NTSB issued its original recommendation to expedite development, certification and production of low-cost proximity warning and conflict detection systems for general aviation [1]. While some systems are in place (TCAS [2]), ¡¨see-and-avoid¡¨ remains the primary means of separation between light aircrafts sharing the national airspace. The requirement for a collision avoidance or sense-and-avoid capability onboard unmanned aircraft has been identified by leading government, industry and regulatory bodies as one of the most significant challenges facing the routine operation of unmanned aerial systems (UAS) in the national airspace system (NAS) [3, 4]. In this thesis, we propose and develop a novel image-based collision avoidance system to detect and avoid an upcoming conflict scenario (with an intruder) without first estimating or filtering range. The proposed collision avoidance system (CAS) uses relative bearing ƒÛ and angular-area subtended ƒê , estimated from an image, to form a test statistic AS C . This test statistic is used in a thresholding technique to decide if a conflict scenario is imminent. If deemed necessary, the system will command the aircraft to perform a manoeuvre based on ƒÛ and constrained by the CAS sensor field-of-view. Through the use of a simulation environment where the UAS is mathematically modelled and a flight controller developed, we show that using Monte Carlo simulations a probability of a Mid Air Collision (MAC) MAC RR or a Near Mid Air Collision (NMAC) RiskRatio can be estimated. We also show the performance gain this system has over a simplified version (bearings-only ƒÛ ). This performance gain is demonstrated in the form of a standard operating characteristic curve. Finally, it is shown that the proposed CAS performs at a level comparable to current manned aviations equivalent level of safety (ELOS) expectations for Class E airspace. In some cases, the CAS may be oversensitive in manoeuvring the owncraft when not necessary, but this constitutes a more conservative and therefore safer, flying procedures in most instances.

Design issues and caching strategies for CD-ROM based multimedia storage

CD-ROMs have proliferated as a distribution media for desktop machines for a large variety of multimedia applications (targeted for a single-user environment) like encyclopedias, magazines and games. With CD-ROM capacities up to 3 GB being available in the near future, they will form an integral part of Video on Demand (VoD) servers to store full-length movies and multimedia. In the first section of this paper we look at issues related to the single- user desktop environment. Since these multimedia applications are highly interactive in nature, we take a pragmatic approach, and have made a detailed study of the multimedia application behavior in terms of the I/O request patterns generated to the CD-ROM subsystem by tracing these patterns. We discuss prefetch buffer design and seek time characteristics in the context of the analysis of these traces. We also propose an adaptive main-memory hosted cache that receives caching hints from the application to reduce the latency when the user moves from one node of the hyper graph to another. In the second section we look at the use of CD-ROM in a VoD server and discuss the problem of scheduling multiple request streams and buffer management in this scenario. We adapt the C-SCAN (Circular SCAN) algorithm to suit the CD-ROM drive characteristics and prove that it is optimal in terms of buffer size management. We provide computationally inexpensive relations by which this algorithm can be implemented. We then propose an admission control algorithm which admits new request streams without disrupting the continuity of playback of the previous request streams. The algorithm also supports operations such as fast forward and replay. Finally, we discuss the problem of optimal placement of MPEG streams on CD-ROMs in the third section.

Ultrasonic evaluation of delamination in quasi-isotropic CFRP laminates subjected to low-velocity impact

Ultrasonic C-Scan is used very often to detect flaws and defects in the composite components resulted during fabrication and damages resulting from service conditions. Evaluation and characterization of defects and damages of composites require experience and good understanding of the material as they are distinctly different in composition and behavior as compared to conventional metallic materials. The failure mechanisms in composite materials are quite complex. They involve the interaction of matrix cracking, fiber matrix interface debonding, fiber pullout, fiber fracture and delamination. Generally all of them occur making the stress and failure analysis very complex. Under low-velocity impact loading delamination is observed to be a major failure mode. In composite materials the ultrasonic waves suffer high acoustic attenuation and scattering effect, thus making data interpretation difficult. However these difficulties can be overcome to a greater extent by proper selection of probe, probe parameter settings like pulse width, pulse amplitude, pulse repetition rate, delay, blanking, gain etc., and data processing which includes image processing done on the image obtained by the C-Scan.

Moderate energy impact analysis combining phenomenological contact law with localised damage and integral equation method

A computational impact analysis methodology has been developed, based on modal analysis and a local contact force-deflection model. The contact law is based on Hertz contact theory while contact stresses are elastic, defines a modified contact theory to take account of local permanent indentation, and considers elastic recovery during unloading. The model was validated experimentally through impact testing of glass-carbon hybrid braided composite panels. Specimens were mounted in a support frame and the contact force was inferred from the deceleration of the impactor, measured by high-speed photography. A Finite Element analysis of the panel and support frame assembly was performed to compute the modal responses. The new contact model performed well in predicting the peak forces and impact durations for moderate energy impacts (15 J), where contact stresses locally exceed the linear elastic limit and damage may be deemed to have occurred. C-scan measurements revealed substantial damage for impact energies in the range of 30-50 J. For this regime the new model predictions might be improved by characterisation of the contact law hysteresis during the unloading phase, and a modification of the elastic vibration response in line with damage levels acquired during the impact. © 2011 Elsevier Ltd. All rights reserved.

Moderate speed impact damage to 2D-braided glass-carbon composites

Hybrid glass-carbon 2D braided composites with varying carbon contents are impacted using a gas gun by impactors of masses 12.5 and 44.5. g, at impact energies up to 50. J. The damage area detected by ultrasound C-scan is found to increase roughly linearly with impact energy, and is larger for the lighter impactor at the same impact energy. The area of whitening of the glass tows on the distal side corresponds with the measured C-scan damage area. X-ray imaging shows more intense damage, at the same impact energy, for a higher-mass impactor. Braids with more glass content have a modest increase in density, decrease in modulus, and reduction in the C-scan area and dent depth at the impact site, particularly at the higher impact energies. Impact damage is found to reduce significantly the compressive strength, giving up to a 26% reduction at the maximum impact energy. © 2012 Elsevier Ltd.

Characterization of impact induced damage modes in single lap joints of woven GFRP composites

Single lap joints of woven GFRP composites have been investigated for impact induced damage modes using C-scan, X-ray micro tomography, imaging and finite element (FE) modelling. This has allowed for damage modes to be observed in 3D from macro to micro level-resulting in much better understanding of damage mechanisms and realistic FE modelling.

Research on nitrogen implantation energy dependence of the properties of SIMON materials

With different implantation energies, nitrogen ions were implanted into SIMOX wafers in our work. And then the wafers were subsequently annealed to form separated by implantation of oxygen and nitrogen (SIMON) wafers. Secondary ion mass spectroscopy (SIMS) was used to observe the distribution of nitrogen and oxygen in the wafers. The result of electron paramagnetic resonance (EPR) was suggested by the dandling bonds densities in the wafers changed with N ions implantation energies. SIMON-based SIS capacitors were made. The results of the C-V test confirmed that the energy of nitrogen implantation affects the properties of the wafers, and the optimum implantation energy was determined. (c) 2005 Elsevier B.V. All rights reserved.

Research on nitrogen implantation energy dependence of the properties of SIMON materials

With different implantation energies, nitrogen ions were implanted into SIMOX wafers in our work. And then the wafers were subsequently annealed to form separated by implantation of oxygen and nitrogen (SIMON) wafers. Secondary ion mass spectroscopy (SIMS) was used to observe the distribution of nitrogen and oxygen in the wafers. The result of electron paramagnetic resonance (EPR) was suggested by the dandling bonds densities in the wafers changed with N ions implantation energies. SIMON-based SIS capacitors were made. The results of the C-V test confirmed that the energy of nitrogen implantation affects the properties of the wafers, and the optimum implantation energy was determined. (c) 2005 Elsevier B.V. All rights reserved.

复杂裂隙岩体统计断裂本构关系与变形参数研究

Rock mass is widely recognized as a kind of geologic body which consists of rock blocks and discontinuities. The deformation and failure of rock mass is not only determined by rock block，but also by discontinuity which is virtually more important. Mutual cutting and combination of discontinuities controlled mechanical property of rock mass. The complex cutting of discontinuities determine the intense anisotropy on mechanical property of rock mass，especially under the effect of ground stress. Engineering practice has show that the brittle failure of hard rock always occurs when its working stress is far lower than the yield strength and compressive strength，the failure always directly related to the fracture propagation of discontinuities. Fracture propagation of discontinuities is the virtue of hard rock’s failure. We can research the rock mass discontinuous mechanical properties precisely by the methods of statistical analysis of discontinuities and Fracture Mechanics. According to Superposition Principle in Fracture Mechanics，A Problem or C Problem could be chosen to research. Problem A mainly calculates the crack-tip stress field and displacement field on internal discontinuities by numerical method. Problem C calculate the crack-tip stress field and displacement field under the assumption of that the mainly rock mass stress field has been known. So the Problem C avoid the complex mutual interference of stress fields of discontinuities，which is called crack system problem in Fracture Mechanics. To solve Problem C, field test on stress field in the rock mass is needed. The linear Superposition of discontinuities strain energies are Scientific and Rational. The difference of Fracture Mechanics between rock mass and other materials can mostly expression as：other materials Fracture Mechanics mostly face the problem A，and can’t avoid multi-crack puzzle, while the Rock mass Fracture Mechanics answer to the Problem C. Problem C can avoid multi-discontinuities mutual interference puzzle via the ground stress test. On the basis of Problem C, Fracture Mechanics could be used conveniently in rock mass. The rock mass statistics fracture constitutive relations, which introduced in this article, are based on the Problem C and the Discontinuity Strain Energy linear superposition. This constitutive relation has several merits: first, it is physical constitutive relation rather than empirical; second, it is very fit to describe the rock mass anisotropy properties; third, it elaborates the exogenous factors such as ground stress. The rock mass statistics fracture constitutive relation is the available approach to answer to the physical, anisotropic and ground stress impacted rock mass problems. This article stand on the foundation of predecessor’s statistics fractures constitutive relation, and improved the discontinuity distributive function. This article had derived the limitation of negative exponential distribution in the course of regression analysis, and advocated to using the two parameter negative exponential distribution for instead. In order to solve the problems of two-dimension stability on engineering key cross-sectional view in rock mass, this article derived the rock mass planar flexibility tensor, and established rock mass two-dimension penetrate statistics fracture constitutive relation on the basis of penetrate fracture mechanics. Based on the crack tip plasticity research production of penetrate fracture, for example the Irwin plasticity equifinality crack, this article established the way to deal with the discontinuity stress singularity and plastic yielding problem at discontinuity tip. The research on deformation parameters is always the high light region of rock mass mechanics field. After the dam foundation excavation of XiaoWan hydroelectric power station, dam foundation rock mass upgrowthed a great deal of unload cracks, rock mass mechanical property gotten intricacy and strong anisotropy. The dam foundation rock mass mostly upgrowthed three group discontinuities： the decantation discontinuity, the steep pitch discontinuity, and the schistosity plane. Most of the discontinuities have got partial unload looseness. In accordance with ground stress field data, the dam foundation stress field greatly non-uniform, which felled under the great impaction of tectonic stress field, self-weight stress field, excavation geometric boundary condition, and excavation, unload. The discontinuity complexity and stress field heterogeneity, created the rock mass mechanical property of dam foundation intricacy and levity. The research on the rock mass mechanics, if not take every respected influencing factor into consideration as best as we can, major errors likely to be created. This article calculated the rock mass elastic modulus that after Xiao Wan hydroelectric power station dam foundation gutter excavation finished. The calculation region covered possession monolith of Xiao Wan concrete double-curvature arch dam. Different monolith were adopted the penetrate fracture statistics constitutive relation or bury fracture statistics constitutive relation selectively. Statistics fracture constitutive relation is fit for the intensity anisotropy and heterogeneity rock mass of Xiao Wan hydroelectric power station dam foundation. This article had contrastive analysis the statistics fracture constitutive relation result with the inclined plane load test actual measurement elastic modulus and RMR method estimated elastic modulus, and find that the three methods elastic modulus have got greatly comparability. So, the statistics fracture constitutive relations are qualified for trust. Generally speaking，this article had finished following works based on predecessors job: “Argumentation the C Problems of superposition principle in Fracture Mechanics, establish two-dimension penetrate statistics fracture constitutive relation of rock mass, argue the negative exponential distribution limitation and improve it, improve of the three-dimension berry statistics fracture constitutive relation of rock mass, discontinuity-tip plastic zone isoeffect calculation, calculate the rock mass elastic modulus on two-dimension cross-sectional view”. The whole research clue of this article inherited from the “statistics rock mass mechanics” of Wu Faquan（1992）.

A computational study of the characteristics of aircraft post-crash fires

Full-scale furnished cabin fires have been studied experimentally for the purpose of characterising the post-crash cabin fire environment by the US Federal Aviation Administration for many years. In this paper the Computational Fluid Dynamics fire field model SMARTFIRE is used to simulate one of these fires conducted in the C-133 test facility in order to provide further validation of the computational approach and the SMARTFIRE software. The experiment involves exposing the interior cabin materials to an external fuel fire, opening only one exit at the far end of the cabin (the same side as the rupture) for ventilation, and noting the subsequent spread of the external fire to the cabin interior and the onset of flashover at approximately 210 seconds. Through this analysis, the software is shown to be in good agreement with the experimental data, producing reasonable agreement with the fire dynamics prior to flashover and producing a reasonable prediction of the flashover time i.e. 225 seconds. The paper then proceeds to utilize the model to examine the impact on flashover time of the extent of cabin furnishings and cabin ventilation provided by available exits

La actividad f??sico-deportiva extraescolar : la influencia en el autoconcepto de los adolescentes y la motivaci??n en la participaci??n en clases regladas de Educaci??n F??sica : un estudio del Colegio San Fernando de Avil??s (Asturias)

Conocer si la pr??ctica asidua de una actividad deportiva extraescolar tiene influencia en la motivaci??n y diversi??n con la que participan en clase de Educaci??n F??sica escolar obligatoria y si repercute todo ello en el autoconcepto del alumnado de Educaci??n Secundaria Obligatoria del Colegio San Fernando de Avil??s (Asturias). Se tratan de demostrar las siguientes hip??tesis: a) Los adolescentes que practican actividades f??sico-deportivas extraescolares tienen m??s elevado el autoconcepto de las dimensiones personales, f??sicas y sociales que los que no realizan dicha actividad; b) El autoconcepto de los adolescentes deportistas influye positivamente en la diversi??n, motivaci??n y participaci??n en las clases de Educaci??n F??sica. Ocho grupos de alumnos/as que pertenecen al segundo ciclo de Ense??anza Secundaria Obligatoria (cuatro de tercer curso y cuatro a cuarto curso) del Colegio San Fernando de Avil??s (Asturias). El total de la muestra es de 217 alumnos del segundo ciclo de la muestra con una media de edad de 14,73 a??os, siendo el cuarenta por ciento chicas y el sesenta por ciento chicos. Las variables estudiadas son: a) Variables sociodemogr??ficas: edad y sexo; b) Variables personales: curso, estudios del padre/madre; c) Variables de h??bitos deportivos: pr??ctica deportiva, deporte que practica, federado, nivel y horas de entrenamiento; d) Dimensi??n general del autoconcepto, habilidad f??sica, apariencia f??sica, honestidad, estabilidad emocional, relaci??n con los padres, relaci??n con los iguales; e) Diversi??n de los sujetos con la actividad f??sica y de motivaci??n de logro; f) Variables extra??as: factores psicol??gicos. Para la comprobaci??n de las hip??tesis de partida se aplicaron los siguientes instrumentos: a) El test del Self-Description Questionaire II (S.D.Q.-II) de Marsh (1992); b) El test de diversi??n con la pr??ctica deportiva en las clases de Educaci??n F??sica de Duda y Nicholls (1992); c) El test de motivaci??n de logro en Educaci??n F??sica (M.E.F.) elaborado por Nishida (1988). a) Los alumnos que practican deporte extraescolar tienen el autoconcepto m??s alto en la dimensi??n general, de apariencia f??sica y de habilidad f??sica que los alumnos que no practican actividades f??sico -deportivas extraescolares; b) En las dimensiones de honestidad y relaciones con iguales de distinto sexo el autoconcepto es menor en los que realizan pr??cticas deportivas; c) Los chicos tienen mejor autoconcepto en la dimensi??n general, habilidad f??sica, honestidad, estabilidad emocional y relaci??n con los padres y las chicas en la apariencia f??sica, relaci??n con los iguales de igual y distinto sexo; d) Los estudios de los padre influyen inversamente, es decir, cuantos menos estudios m??s alto es el autoconcepto de la dimensiones general, habilidad f??sica y apariencia f??sica en comparaci??n con los que tienen los niveles m??s altos de estudios; e) En l??neas generales, los alumnos tienen una buena predisposici??n para las clases, muestran inter??s y disfrutan con las sesiones de Educaci??n F??sica; f) Posiblemente la pr??ctica deportiva pueda ser un factor que ayude a mitigar la fluctuaci??n en el autoconcepto que tiene lugar en el periodo adolescente; g) Adem??s de las clases de Educaci??n F??sica, deber??a de proponerse una actividad alternativa, una formaci??n deportiva de base, que sirva como resorte para hacer frente y compensar las distintas problem??ticas que viven los j??venes actuales; h) A mayor compromiso con la pr??ctica deportiva, los adolescentes experimentan mayores beneficios en algunas dimensiones del autoconcepto. De tal modo que aquellos adolescentes que practican actividades f??sico-deportivas extraescolares regularmente presentan mejores autopercepciones en algunos dominios del autoconcepto.

La educación de las relaciones espaciales en el niño deficiente mental.

La investigación analiza la educación de las relaciones espaciales en el niño deficiente mental. Hipótesis: a) Los sujetos que reciban un programa educativo adecuado a su estado evolutivo mejorarán su capacidad de representación del espacio topológico: lograrán una más rápida y mejor construcción de las relaciones más simples de la concepción espacial según la génesis propuesta por J. Piaget; b) Los sujetos deficientes mentales son capaces de desarrollar sus potencialidades de representación del espacio topológico si se les aplica un programa educativo adecuado a su capacidad intelectual. Los sujetos estudiados son niños de edades cronológicas situadas entre los 7 y los 10 años, que presentan un nivel evolutivo en la representación de las relaciones topológicas del primer y segundo estadio del período preoperacional según Piaget e Inhelder. La población la componen 26 sujetos de estas características, de entre los que, de forma aleatoria se seleccionaron 14, utilizando una tabla de números aleatorios, que componían la muestra de sujetos experimentales. Variables independientes: a) Capacidad mental del sujeto y b) Programa educativo propuesto por el investigador. Variable dependiente: nivel de desarrollo en la representación del espacio topológico del niño, que vendrá determinado y cuantificado por los resultados obtenidos en las pruebas operatorias que enuncian Piaget e Inhelder para el análisis genético de las relaciones constitutivas del espacio topológico. Las pruebas utilizadas son: a) Relaciones de vecindad medidas por una prueba de percepción háptica; b) Relaciones de separación medidas por una prueba de dibujo de figuras geométricas simples; c) Relaciones de orden medidas por una prueba de seriación y reunión y d) Relaciones de envolvimiento medidas por una prueba de nudos. Las pruebas se aplicaron durante 66 sesiones, con una duración que oscilaba entre 45 y 60 minutos. Se siguió esta cronología: a) Pre-test: antes de iniciar la aplicación del programa para conocer y determinar el nivel de desarrollo de las relaciones topológicas en la concepción espacial de los sujetos; b) Test: tras la aplicación del programa para comprobar la evaluación, tanto del grupo experimental como del grupo de control; c) Re-test: transcurridos 40 días desde la aplicación del test, para comprobar la estabilidad de los resultados. Se concluye que la variable 'programa educativo' provoca un aumento estadísticamente significativo en la evolución general de las relaciones constitutivas del espacio topológico en los niños del período pre-operacional. El resultado del análisis pone de relieve la importancia de aplicar un proceso educativo adecuado a los sujetos deficientes, que provoque un progreso en su desarrollo intelectual. a) La aplicación del programa educativo experimental repercute positivamente en la construcción de las relaciones espaciales en el niño del período pre-operacional; b) En el caso de aplicar el programa a niños con retraso intelectual se produce un aceleramiento significativo en la evolución de sus estructuras mentales hasta el punto que llega a ser superior al observado en niños normales de su mismo nivel inicial, pero que no han recibido el programa propuesto y c) Se constata que los resultados obtenidos tras la aplicación del programa se mantienen estables según la prueba de re-test efectuada tras un período considerable de tiempo sin la influencia de la programación especial y ello tanto en los sujetos del área de pre-escolar como en los del área de nivelación.