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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Investigação ab initio dos mecanismos de formação de nanoligas core-shell com platina e metais de transição dos períodos 3d, 4d e 5d / Ab initio investigation of mechanisms of formation of core-shell nanoalloys with platinum and 3d, 4d, and 5d transition metals

Justo, Stella Granatto 06 December 2017 (has links)
Nanoligas bimetálicas têm atraído a atenção de pesquisadores nas últimas décadas devido a possibilidade de ajustar suas propriedades físico-químicas, tais como propriedades elétricas, ópticas, magnéticas e de reatividade, por meio da variação do número de átomos, da composição química e do formato geométrico. As nanoligas bimetálicas que combinam Pt com outros metais são especificamente interessantes na área de catálise heterogênea, devido a possibilidade de se obter materiais com propriedades distintas de seus respectivos sistemas unários no que se refere ao surgimento ou aumento da atividade catalítica, à seletividade e, muitas vezes, ao preço reduzido. Esse trabalho tem como objetivo investigar as propriedades estruturais, energéticas, eletrônicas e de estabilidade de nanoligas bimetálicas core-shell de 55 átomos que combinam Pt com metais de transição (MT) pertencentes às séries de transição 3d, 4d e 5d dos grupos de Fe a Zn. Esses sistemas foram estudados utilizando cálculos de primeiros princípios (ab initio) baseados na teoria do funcional da densidade, tal como implementada no código computacional VASP (Vienna Ab initio Simulation Package). As nanoligas putativas de mínimo global energético (pGMC) de composição Pt13MT42 e Pt42MT13 calculadas nesse estudo apresentaram características particulares quanto à geometria e ao arranjo das espécies metálicas na nanoliga. Ao que diz respeito aos arranjos core-shell, foram observados dois arranjos em que a fica Pt no caroço (Pt13Ag42 e Pt13 Au42) e sete arranjos em que a Pt fica na superfície (Pt42Fe13, Pt42Co13, Pt42Ni13, Pt42Cu13, Pt42Ru13, Pt42Rh13 e Pt42Os13). Os mecanismos que levam à formação destas e das demais nanoligas pGMC foram investigados com base em três fatores: raio atômico, energia de superfície e cargas de Bader. Verificou-se que raio e a energia de superfície competem como fator determinante pelas posições preferenciais de cada espécie metálica na nanoliga. Nos casos em que houve divergência, o raio apresentou-se como o fator de maior importância, entretanto, quando o raio das espécies são muitos próximos, a energia de superfície exerce um papel de maior importância. A partir da análise de cargas de Bader, observou-se ocorrência de transferência de carga da região do caroço para a região da superfície para a maioria das nanoligas. No mais, observou-se que as nanoligas core-shell contam com atração coulômbica de maior magnitude do que as demais nanoligas pGMC, como resultado de altas cargas de sinal oposto em cada uma das regiões. / Bimetallic nanoalloys have been attracting attention since the last decades due to the possibility of adjusting their physical-chemical properties, such as electrical, optical, magnetic and reactivity properties, by means of the variation of the number of atoms, chemical composition and geometry. Bimetallic nanoalloys that combine Pt with other metals are especially interesting for heterogeneous catalysis given the possibility of obtaining materials with properties that differ from their respective unary systems regarding the appearance or increase of catalytical activity, selectivity and, in many cases, reduced cost. The aim of this work is the evaluation of the stability and of structural, energetic and electronic properties of 55 atom core-shell bimetallic nanoalloys that combine Pt with transition metals (MT) from the 3d, 4d, and 5d transition periods from Fe to Zn groups. These systems were studied using first principle (ab initio) calculations based on density functional theory, as implemented in the VASP (Viena Ab initio Simulation Package) computer code. The nanoalloys with Pt13MT42 and Pt42MT13 compositions which were observed as putative global minimum configuration (pGMC) presented unique characteristics regarding their geommetry and the arrangement of the different metals within the nanoalloy. Considering the core-shell nanoalloys, two arrangements in which Pt is located in the core were observed (Pt13Ag42 e Pt13 Au42) as well as seven arrangements with Pt in the surface (Pt42Fe13, Pt42Co13, Pt42Ni13, Pt42Cu13, Pt42Ru13, Pt42Rh13 e Pt42Os13). The mechanisms that lead to the formation of these and of the remaining pGMC nanoalloys were investigated considering three factors: atomic radius, surface energy and Bader charges. It was verified that atomic radius and surface energy compete directly for the determination of preferential sites for the atoms in the nanoalloy. When these two factors diverge, the atomic radius is the most important factor. However, when the radii of the species involved are similar, the surface energy becomes the determining factor. In addition, Bader charges analysis showed that, for most nanoalloys, the core is positively charged and the shell accumulates negative charge, indicating that charge is transfered from the atoms in the core to the ones in the surface. Besides, the core-shell nanoalloys have a higher coulombic attraction in comparison with others pGMC, due to high quantities of charge with opposite sign in each region.
272

Actividad de los músculos paravertebrales durante ejercicios que requieran estabilidad raquídea

Chulvi Medrano, Iván 22 September 2011 (has links)
CONTEXTO: El entrenamiento aplicando elementos de inestabilidad está siendo ampliamente utilizado en el campo del entrenamiento como una herramienta novedosa y eficaz. No obstante, recientes hallazgos aportan datos contrarios a esta creencia y sugieren que la ejecución de ejercicios tradicionales sobre superficies inestables o ejercicios calisténicos específicos para el fortalecimiento estabilizador pueden no resultar estímulo suficiente para personas con un nivel de entrenamiento elevado llegando incluso a interferencia en el rendimiento final por la reducción de la capacidad de fuerza y la carencia de especificidad del entrenamiento. OBJETIVO: Cuantificar y comparar la actividad muscular paraespinal y la capacidad de generar fuerza máxima isométrica durante ejercicios globales que requieres de estabilidad frente a los ejercicios específicos calisténicos para el fortalecimiento estabilizador y los ejercicios que combinan inestabilidad externa. MATERIAL Y MÉTODOS: 31 sujetos altamente entrenados, con experiencia en el entrenamiento con elementos inestables y sin patologías de espalda fueron reclutados voluntariamente para la realización del estudio descriptivo. Tras un calentamiento estandarizado fueron colocados los electrodos para el registro muscular del multifidus (lumbar, torácico), erector espinae (lumbar, torácico). Con esta instrumentación los sujetos realizaron de forma aleatoria y dejando siempre un mínimo de 3 minutos de descanso los siguientes ejercicios: i) extensión lumbar; ii) extensión lumbar T-Bow; iii) lunge; iv) sentadilla con inestabilidad [Bosu, T-Bow]; v) peso muerto; vi) peso muerto con inestabilidad [Bosu, T-Bow]. Para todos los ejercicios se realizaron dos condiciones de evaluación, fuerza máxima contracción isométrica voluntaria (MCIV) y 10 repeticiones al 70% (MCIV). Los datos fueron registrados y almacenados para su posterior tratamiento estadístico con el SPSS 17.0. RESULTADOS: Durante las mediciones estáticas y dinámicas de siempre existió una mayor activación muscular y registros de fuerza máxima isométrica (MCIV) (p<0.05) para las condiciones de estabilidad frente a las de inestabilidad. Los registros más elevados los obtuvo el ejercicio de peso muerto donde la fuerza máxima isométrica voluntaria media fue de 107.85 (5.15) Kg. Mientras que la respuesta muscular global paraespinal en condiciones de estabilidad realizado al 70% (MCIV) fueron [máximo registro dinámico 117.38 (5.49) % y media dinámica 88.53 (2.97) %)]. CONCLUSIÓN: Añadir elementos de inestabilidad reduce la capacidad de generar fuerza máxima isométrica. La realización de los ejercicios globales al 70 % (MCIV) en condiciones de estabilidad generan la misma (lunge) o mayor (peso muerto) actividad muscular que los mismos ejercicios realizados con elementos de inestabilidad o con ejercicios específicos calisténicos. Por último, los datos parecen indicar que las respuestas musculares y la reducción en la capacidad de generar fuerza dependerán de los grados de inestabilidad que genere el dispositivo sobre el que se realice el ejercicio. / CONTEXT: It’s unclear whether unstable conditions during traditional resistance exercises performed at moderate loads can provoke higher levels of paraespinal muscular activation in healthy/athletic populations than the stable exercises performed at high loads. By other hand it has suggested that use unstable devices can reduce de strength performance output. PURPOSE: To quantify and to compare paraespinal muscular activity and maximum isometric voluntary contraction (MIVC) while carrying out different exercises polyarticular and calisthenic specific lumbar strengthening exercises in both stable and unstable conditions. MATERIAL AND METHODS: 31 subjects highly trained, experienced in training with instability and without pathologies were voluntarily recruited back to the descriptive study. Following a standardized warming the electrodes were placed to record the multifidus and erector espinae both in lumbar and thoracic portion. Subjects performed at random and always leaving a minimum of 3 minutes of rest for the following exercises: i) lumbar extension; ii) T-Bow lumbar extension; iii) lunge; iv) unstable squat [Bosu, T- Bow]; v) deadlift; vi) unstable deadlift [Bosu, T-Bow].This exercises were performed two testing conditions, (MIVC) and 10 repetitions at 70% (MIVC). Data were recorded and stored for later statistical analysis with SPSS 17.0. RESULTS: Data shows that there was a greater muscle activation and maximal isometric force records (MCIV) (p <0.05) for the conditions of stability against instability. Records obtained higher the deadlift exercise where the maximum voluntary isometric force average was 107.85 (5.15) kg. While global paraspinal muscle response in a stable made of 70% (MCIV) were [maximum dynamic registration 117.38 (5.49)% and 88.53 running average (2.97 )%)]. CONCLUSION: Add elements of instability reduces the ability to generate maximal isometric force. The overall exercise performance 70% (MCIV) in stable conditions generate the same (lunge) or higher (deadlift) muscle activity that these exercises with elements of instability or specific exercises calisthenics.
273

µL

Wu, Huie-wen 13 September 2006 (has links)
¡§People¡¨ is the key to a company¡¦s success, as all processes from R&D, sales to services were handled by people. Therefore, quality of a team determines whether a company will be successful or not, and this is exactly why companies starting to pay increasing attention to ¡§core competency¡¨. Technology, products and services can easily be duplicated, but employees are the only, and most important, assets in a company that can not be replaced. Excellence employees will lead to the competitiveness and profitability of a company and are the foundation of successful companies. It is an imperative for modern companies to cultivate employees¡¦ ¡§core competency¡¨ so that companies can reasonably leverage, motivate and accumulate top quality human assets in order to reach maximum productivity and support the actualization of operation strategy. This study aims at using case study of a software development company of high tech industry to understand the construction of the core competency model and its process. Through literature review, focus groups and executive interviews, the study comes up with the core competency of all employees and the managerial core competency of managers. The study hopes to be able to help other industries to introduce their core competency so as to increase the overall organizational efficiency. Core competency means the knowledge, skills, behaviors and traits that employees need in order for a company to actualize its operation strategy. Therefore, the mid- to long-term business strategy is the base of the development of core competency. The 5 core competencies in the study were developed based on the following factors: company mission and vision, 3 year strategies and goals, unique competitive advantages, key successful factors and the benchmarking of other model companies. Each core competency must have very clear definition and description of its corresponding behaviors of the contribution and impact for various levels of employees. The definition and behaviors descriptions serve as the base for the company¡¦s core competency evaluation and also set the future direction for the company. This study results showed that the company, after introducing core competency system, was able to understand precisely the core competency gap between its individual manager and the team average. The study also demonstrated the fact that the individual manager¡¦s core competency improved visibly in a year through training on the targeted core competencies. This study validated that the organizational efficiency can be increased by the constructing of core competency system and the implementation of the performance management system.
274

The Effects Of Positive Core Self And External Evaluations On Performance Appraisals

Guven, Lale 01 December 2007 (has links) (PDF)
The purpose of this study was to investigate the effects of core self-evaluations (CSEs) and core external-evaluations (CEEs) on performance evaluations. It was hypothesized that people with higher levels of CSEs and CEEs would be more lenient in their performance ratings, when rating neutral performance. The second hypothesis of the study was that people with higher and lower CSEs would engage more in halo when rating neutral performance compared to people with average levels of CSEs. It was further hypothesized that CEEs would moderate the relationship between CSEs and performance ratings given. A total of 129 students from the Middle East Technical University participated in this study. They were given the core self- and external-evaluations scales, as well as two distractor scales (PANAS and Rosenberg Self-Esteem Scale). They were later assigned randomly to either the neutral or the good performance vignette conditions, and asked to rate the performance of a departmental secretary whose performance was described in the vignette using two different performance rating forms that included the relevant performance dimensions and behaviors of the secretary. The first one of these forms is the Behavior Observation Scale (BOS) and the second one is the Graphic Rating Scale (GRS). The results showed that CSEs did not have a significant effect on the performance evaluations given. When the mood of the participants was controlled, however, people who had higher CSEs gave lower performance ratings to neutral performance than people who had lower CSEs, with the GRS as the rating form. Thus, the first hypothesis was not supported and even an opposite effect emerged. The second hypothesis found no support, as the standard deviations of the performance ratings given by people with high, low or average CSEs did not differ significantly from each other for the neutral performance vignette condition, even when the mood of the participants was controlled. However, the standard deviations of the ratings given by participants with average CSEs were higher than that of the participants with low and high CSEs for the good performance vignette condition. Hypothesis three was not supported either, as CEEs were not found to moderate the relationship between CSEs and the performance ratings.
275

The role of rotation and magnetic fields in a core collapse supernova

Akiyama, Shizuka 05 August 2013 (has links)
While the process that converts implosion into explosion in core collapse supernovae is poorly understood, their observed asphericity provides new constraints on the physics of these events. Since pulsars are rotating and magnetized neutron stars, there is no doubt that rotation and magnetic fields are inherent to the exploding engine. We have shown that magnetic field amplification is an inevitable by-product of the differential rotation that accompanies core-collapse. We performed 1D core-collapse simulations of rotating iron cores with various rotational profiles and velocities. We found that differential rotation was a generic feature of rotating iron core collapse. As a result, the magnetorotational instability (MRI) generates magnetic fields of order 10¹⁵⁻¹⁷ G in a few tens of milliseconds where the negative shear is the strongest. Although magnetic fields of order 10¹⁵⁻¹⁷ G are very strong, they are not strong enough to modify the equation of state of degenerate electron gas near the proto-neutron star. The corresponding MHD luminosity available is ~10⁵² erg s⁻¹, which can modify the explosion dynamics if the power is sustained for a fraction of a second. When rotational effects are included, we found that there is a critical iron core rotation rate that gives the most rapidly rotating proto-neutron star, faster than which the rotational velocity of the proto-neutron star decreases due to centrifugal support. This non-monotonic behavior of post-collapse core rotation suggests that the progenitor of the most rapidly rotating proto-neutron star is not the most rapidly rotating iron core, but that those iron cores with nearly the critical initial rotation rate may produce the maximum proto-neutron star rotation, the strongest magnetic fields, and the most robust supernova explosions. Even small rotation may induce non-axisymmetric instabilities, which drive magneto-acoustic flux in to the mantle, transporting enegy out of the proto-neutron star to the region near the stalled shock. Further implications for rotation and magnetic fields, pulsars and magnetars, and jet formation mechanisms are discussed. / text
276

A hybrid MPI/OpenMP parallelization of the adaptive integral method for multi-core clusters

Wei, Fangzhou 02 August 2011 (has links)
A hybrid of message passing and shared memory techniques is presented for scalable parallelization of the adaptive integral method (AIM), an FFT based algorithm, on clusters of identical multi-core processors. The proposed hybrid MPI/OpenMP parallelization scheme is based on a nested one-dimensional (1-D) slab decomposition of the 3-D auxiliary uniform grid and the associated AIM calculations: If there are M processors and T cores per processor, the scheme (i) divides the uniform grid into M slabs and MT sub-slabs, (ii) assigns each slab/sub-slab and the associated operations to one of the processors/cores, and (iii) uses MPI for inter-processor data communication and OpenMP for intra-processor data exchange. The MPI/OpenMP parallel AIM is used to accelerate the MOM solution of combined-field integral equations pertinent to the analysis of scattering from perfectly conducting surfaces. The scalability and efficiency of the implementation are investigated theoretically and verified numerically by solving benchmark scattering problems on a (near) petaflop supercomputing cluster of quad-core processors. The timing and speedup results on up to 1024 processors show that the proposed hybrid MPI/OpenMP parallelization exhibits better strong scalability (fixed problem size speedup) compared to pure MPI parallelization when multiple cores are used on each processor. / text
277

An Analysis of Disability Specific Curriculum In A Specialized School for the Blind: A Case Study

Lohmeier, Keri Lee January 2005 (has links)
This study analyzes the changes in disability-specific curriculum that took place in one specialized school for the blind driven by academic priorities from 1995 to 2005. The framework used in this case study approach analyzed the school's past and present (1) Artifacts - visible organizational structures and materials, (2) Expressed Values- explicitly written or stated beliefs and policies, and (3) Underlying Assumptions- unspoken attitudes and beliefs. Variables for change among the areas of teacher training, team teaching, evaluation systems, IEP's, state standards, the school improvement plan, short term and summer programming, as well as the residential program were all targeted to balance academics with an Expanded Core curriculum. The results indicate a balanced curriculum for some of the variables while other areas continue to reflect the struggle of mandates.
278

Semantinių web technologijų tyrimas ir taikymas video paskaitų sistemoje VIPS / Semantic web technology research and application in video lecturing system VIPS

Karazinas, Evaldas 28 January 2008 (has links)
Šis dokumentas nagrinėja paieškos organizavimo galimybes VIPS sistemos video įrašų archyve pasitelkiant semantines web technologijas. Semantinis žiniatinklis yra dalis pasaulinio interneto, kuriame informacija gali būti suprantama ne tik žmonėms, bet ir programiniams agentams, sukuriant galimybes surasti, pasidalinti ir intergruoti informacija adug paprasčiau. Socialinis žymėjimas taip pat gali grupuoti informaciją semantiniu būdu. Dokumento pradžioje aptariama teorija ir galimi sprendimai, vėliau pateikiamas galimas sprendimo modelis. Dokumentas pabaigiamas išvadomis ir rekomendacijomis. / The aim of this paper is to present search organization opportunities in VIPS system archive in semantic manner. The Semantic Web is an evolving extension of the World Wide Web in which web content can be expressed not only in natural language, but also in a format that can be read and used by software agents, thus permitting them to find, share and integrate information more easily. Social tagging can also group information in semantic manner. Theoretical background of specified model is delivered in the beginning sections of this thesis. As experimental solution information system was introduced. Thesis is concluded and recommendations are suggested for future.
279

Validering av självskattningsformuläret Norwegian Outcome Response System for Evaluation (NORSE) / Validation of the self-report instrument Norwegian Outcome Response System for Evaluation (NORSE)

Axelsson, Julia, Penttinen, Niklas January 2018 (has links)
Syftet med studien var att validera den svenska översättningen av självskattningsinstrumentet Norwegian Outcome Response System for Evaluation (NORSE), ett instrument som används för att mäta psykiskt mående. Data har samlats in genom en digital enkät. Urvalet var icke-kliniskt och bestod av totalt 228 individer. Av de 228 individerna gjorde 30 personer enkäten vid två tillfällen för att testa instrumentets stabilitet över tid. För att validera NORSE användes ett redan validerat och etablerat instrument, Clinical Outcomes in Routine Evaluation Outcome Measure (CORE-OM) som standardreferens. Resultatet visade att den svenska översättningen av NORSE har hög intern konsistens och god test-retest reliabilitet, såväl som god reliabilitet och validitet. Resultaten visade även att NORSE och CORE-OM täcker liknande områden men är samtidigt långt ifrån identiska. Föreliggande studie indikerar att det kan finnas ett användningsområde för den svenska översättningen av NORSE i den svenska primärvården. / The aim of this study was to validate the Swedish translation of the self-report instrument Norwegian Outcome Response System for Evaluation (NORSE), an instrument used to evaluate psychological well-being. Data was collected using a digital questionnaire. The sample was non-clinical and consisted of a total of 228 individuals. Out of the 228 individuals, 30 participants took the questionnaire on two occasions to test the stability of the instrument over time. In order to validate NORSE, an already validated and established instrument, Clinical Outcomes in Routine Evaluation Outcome Measure (CORE-OM) was used as a reference standard. The results showed that the Swedish translation of NORSE has a high internal consistency and good test-retest reliability, as well as a good internal reliability and concurrent validity. Results also showed that NORSE and CORE-OM cover similar areas but are far from identical, thus indicating that there could be a use for NORSE in Swedish primary health care.
280

Smarta kontrakt - vägen mot en helt digitaliserad bank : En studie om blockchain-tekniken inom core banking / Smart contracts - The way towards a fully digital bank

Holmstedt, Sarah, Örnberg, Malin January 2018 (has links)
In the banking industry today there are processes in need of digitalisation to meet the digital needs of the customers. An area which is a candidate for digitalization is core banking which stands for Centralized Online Realtime Exchange and includes processes such as bank loans. By implementing the blockchain technology and smart contracts to core banking processes they can become digital and meet needs such as efficiency and transparency. The purposes of this master thesis are to examine the attitude Swedish banks have towards the blockchain technology, find out what core banking processes that could benefit from an implementation of a smart contract, and create an implementation model of a specific core banking process as a smart contract. By examining these topics a holistic perspective of how the blockchain technology can create value for the banks and customers can be reached to create a proof of concept model of a core banking process with the blockchain technology and smart contracts. The purposes are fulfilled by a literature study, interviews with representatives from Swedish banks, legal experts and requirements specialists and a model consisting of flowcharts, requirements,specifications, stakeholders and models in the blockchain platform Corda. Generally the banks have a positive attitude towards the blockchain technology but there are regulations that hinder the development process. Promissory notes was the process chosen to be implemented as a smart contract since itscharacteristics are fulfilled by the blockchain technology and according to thebanks this process would create the most value. According to a evaluation by the requirement experts at the employer Applicon the implementation model is suitable as a proof of concept and a good base for future prototyping.

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