A presente pesquisa centra-se no estudo das relações entre memória de curto prazo, memória de trabalho, velocidade de processamento, processamento visuoespacial, funções executivas, atenção seletiva e alternada e desempenho matemático, uma vez que essas relações podem esclarecer as diferenças entre os alunos na aprendizagem da matemática. O trabalho teve como objeto de observação crianças da 2ª série do ensino fundamental. Consiste em um estudo com base correlacional e comparativa. A amostra desta pesquisa é composta por 40 alunos, com idade entre 8 e 9 anos. A investigação envolvendo o funcionamento neuropsicológico e o desempenho cognitivo na aprendizagem matemática é relevante, pois para desenvolver habilidades de cálculo matemático é fundamental que o aluno tenha construído o conceito de número e esta construção está vinculada ao desenvolvimento das funções neuropsicológicas. O desempenho matemático é avaliado através da Prova de Aritmética de Capovilla, Montiel e Capovilla (2007) e as funções neuropsicológicas, através de quatro subtestes da Escala Wechsler WISCIII, que são: Memória de Curto Prazo – teste de Dígitos de Ordem Direta; Memória de Trabalho – Dígitos de Ordem Inversa; Velocidade de Processamento - Procurar Símbolos e Códigos; Percepção Visuoespacial – teste de Cubos. A Função Executiva é avaliada através do Teste das Trilhas de Montiel e Capovilla (2007) e a Atenção, através do Teste de Atenção por Cancelamento de Montiel e Capovilla (2007). Observa-se uma correlação significativa entre Desempenho Matemático e Memória de Curto Prazo, Velocidade de Processamento, Função Executiva e Atenção. Neste estudo, não se encontrou uma correlação estatisticamente significativa entre as funções Memória de Trabalho e Processamento Visuoespacial. / This paper approaches the relationship amongst neuropsychological functions –Short Term Memory (STM), Working Memory (WM), Speed Processing (SP), Visual Spatial Perception (VSP), Executive Functions (EF), Attention (A) and Math Performance (MP) in 2nd grade children at a public Elementary School from Porto Alegre. It is a comparative and correlation study. The sample of this research is composed for 40 pupils with are between 8 and 9 years. Research involving neuropsychological functioning and cognitive performance in mathematics is pertinent, for it is essential that the student build the notion of number in order to develop mathematical skills and such construction relies on the expansion of neuropsychological functions. The mathematical performance is measured by the Arthmetic Test of Capovilla, Montiel and Capovilla (2007) and the neuropsychological functions are verified by subtests Wechsler WIS CIII; Short Term Memory is assessed by the Digits in Direct Order, while the Working Memory is established by the Digits in Reverse Order. The speed processing is assessed through the use of Find Symbols and Codes activities, and spatial perception is confirmed by the utilization of cubes. The Executive Function is assessed by the Trail Making of Montiel and Capovilla (2007) and attention is assessed by the Attention Test for Cancellation of Montiel and Capovilla (2007). There is a momentous correlation amid math performance and Short-Term Memory, speed processing, executive function and attention. This study one did not mett, however, the establishment of a statistically significant correlation between the Working Memory functions and the Visual Spatial Processing.

O Brasil é um país de dimensões continentais, onde existe uma considerável distância entre a geração e os principais centros de consumo. Dessa forma, o estudo e desenvolvimento de novas tecnologias de transmissão a longas distâncias é de fundamental importância para o desenvolvimento do país. A solução mais utilizada atualmente é a transmissão em corrente alternada. Entretanto a transmissão em corrente continua também é uma solução viável para longas distâncias. O sistema brasileiro é composto principalmente por linhas 500 kV em corrente alternada (também há 230; 345; 440 e 750 kV), bem como em corrente continua (em ±600 e ±800 kV). O presente estudo apresenta uma solução de transmissão em corrente alternada por linhas de 1000 kV, que se mostrou mais econômico na transmissão de potências superiores a 3.500 MW e distâncias de 1400km. Nos próximos anos, a geração de energia elétrica no Brasil será expandida de forma significativa, ocorrerá um aumento principalmente na geração de energia eólica e solar, localizadas em sua maioria na região Nordeste do país. Esse aumento na geração exigirá a transmissão de grandes blocos de energia elétrica por distâncias significativas, devido à falta de proximidade entre a geração e os principais centros consumidores, que estão localizados no Sudeste. Neste estudo, serão mostradas as etapas de definição de condutor economicamente mais adequado e projeto da geometria da torre. Com base nos dados obtidos, será feita a avaliação do desempenho da linha 1000 kV, durante a operação normal de fluxo de carga, curtos-circuitos e estabilidade. / Brazil, a country of continental proportions, have significant distance between the power generation centers and the main consumer centers. In such way, the study and development of new transmission technologies over long distances is of fundamental importance for the development of the country. Nowadays, the most commonly used solution is alternating current transmission. However, direct current transmission is also a viable solution for long distances. The Brazilian system mainly consists of 500 kV alternating current lines (along with 230, 345, 440 and 750 kV) and direct current lines (± 600 and ± 800 kV). This study provides a solution for transmission in alternating current by lines of 1000 kV, which proved to be more economical in power transmission over 3,500 MW and distances beyond 1400km. In the coming years, the electric power generation in Brazil will expand significantly; a boost will take place mainly in wind and solar power generation, located mostly in the Northeast of the country. This generation expansion will require transmission of large blocks of electric power over considerable distances, due to the lack of proximity between generation sites and main consumer centers located in the Southeast. This study will show the setting stages of the most economically applicable conductor and tower geometry design. Based on the data obtained, the performance of the 1000 kV line will be evaluated during the regular load flow operation, short circuits and stability.

The chief subject of this dissertation is a description of the reflections on the poetry of 19th and 20th century, in connection with questions of national identity, national self-confidence, tradition and openness to European space. I deal with the question, how these topics are (often unconsciously) reflected in the prosodic debates of certain periods (especially during the Czech National Revival or at the time of the formation of independent Czechoslovakia) and how influence the views on how the Czech verse looks or should look, for what purposes poetry is to serve or what threatens the national literature and language. I also follow the changes in the relation of the theory of verse to the poetry itself and compare the concept of the verse and its basic categories in Czech and international theory. This work is composed of four isolated parts, relatively independent of each other. These are partial probes on selected topics from the history of Czech and foreign literature and its reflection. The first chapter focuses on the syllabotonic reform of the Czech verse and on the motivation, which led to its acceptance or rejection. I investigated the reasons, which led some authors to the partial violation of rules and some authors to attempts to establish quantitative verse. The topic of Czech iamb...

傳統的主成分分析(principal component analysis)法，只能分析二式二向的資料(2-mode 2-way data)，若是要處裡三向三式的資料(3-mode 3-way data)或是更多維的資料，則必須用其它的方法。例如將某一向資料取平均數，再做分析。此法雖然可行，但卻忽略三向資料間可能潛藏的相關性。且社會科學的研究日趨複雜，三向資料也就更常見到，而我們可能也對三向資料間彼此的關聯感到興趣。因此在1960、1970年代，學者開始研究將主成分分析的模型加以擴展成適合分析三向資料的模型。本文除了介紹三向資料主成分分析所使用的Tucker3模型及其參數估計法外，也以28家股票上市公司為實例，探討資本結構影響因素於五年間（1989~1993年）在不同公司群組間的變化情形。

Poor settling of solids increases land requirement for tailings containment and imposes severe constraints on the water balance. Consequent to these considerations, the alternating current electrocoagulation (AC/EC) technique emerged as a candidate for enhancing the settling behaviour of suspensions in the mineral, coal and oil sands industries. Hence, a fundamental study of AC/EC was undertaken with aluminum electrodes. Ground silica (d50 = 20 m), which formed a stable suspension, served as the model tailings solid at 5.0 wt % in water. The AC/EC process consisted of two developmental stages: coagulation, marked by pH decrease in the silica suspension; and floc growth, characterized by pH increase from the minimum (i.e., the end of coagulation). AC/EC enhanced the initial settling rate of silica by over three orders of magnitude, and exhibited remarkable flexibility by virtue of the wide range of process parameters that could be optimized. For example, AC/EC can be operated in either the indirect or direct mode. The settling behaviour of bentonite (estimated d50 < 1 m) was more enhanced by indirect AC/EC, while that of silica benefited more from direct AC/EC. Any condition that increased aluminum dosage (e.g., current, retention time), increased the initial settling rate of silica. Over the feed water pH range of 3.0 to 9.1, AC/EC was effective in enhancing the settling behaviour of silica. AC/EC was also effective over a wide range of temperatures (23 to 85C). High electrical energy demand by AC/EC was observed throughout this study. Its optimization was beyond the scope of this work. Dilution of a sample of Syncrude mature fine tailings (MFT) to 4.6 wt % solids sustained a stable suspension. Settling occurred after AC/EC treatment, a crystal-clear supernatant resulted and bitumen was recovered as froth. Entrained solids were easily spray-washed from the froth with water. The settling behaviour of a Luscar Sterco fine coal tailings sample was not augmented by AC/EC, possibly due to contamination by the companys own electrocoagulation operation. After having been stored dry for more than a year, electrocoagulated silica was an effective coagulant for as-received silica and Syncrude MFT. / Chemical Engineering

El objetivo fundamental de este trabajo ha sido el estudio del sistema fundamental de paralelos de un cuerpo convexo (conjunto compacto y convexo) en el espacio euclídeo n-dimensional. Se ha llevado a cabo siguiendo tres líneas diferentes: el estudio del polinomio de Steiner y el polinomio alternado Steiner desde el punto de vista algebraico de sus raíces y la conjetura de Matheron; el estudio de la diferenciabilidad de las quermassintegrales asociadas al cuerpo con respecto al parámetro de definición del sistema completo de paralelos y, por último, el estudio de las quermassintegrales del cuerpo desde el punto de vista analítico proporcionado por la identificación del cuerpo convexo con su función soporte, las propiedades de ésta cuando el cuerpo es suficientemente suave y la desigualdad de Brunn-Minkowski. / The aim of this work consists on studying the full system of parallel bodies of a convex body (compact and convex set) in the n-dimensional Euclidean space. It has been carried out following three different lines of work: the study of the Steiner polynomial and the alternating Steiner polynomial from the algebraic point of view of its roots; the study of the differentiability of the quermassintegrals associated to the convex body with respect to the parameter that defines the full system of parallel bodies and finally, the study of the quermassintegrals from the analytical point of view provided by the identification of a convex body with its support function, the properties of this function when the body is smooth enough and the Brunn-Minkowski inequality

In the fast growing field of Telecommunications, the back up DC power supply plays a vital role in powering the telecom equipment. This DC power supply is a combination of AC-DC Rectifier coupled with a battery bank to support the load when AC input is not available. Figures 0.1 and 0.2 show the line diagram of the DC power supply. The power supply is the most critical element in a telecom installation and it should be highly reliable in order to have un-interrupted service. (Fig) Besides reliability, power density and cost are the driving forces behind the success of a power supply in the market. Off late, the reach of telecom in the society is very wide covering remote villages and major metros. Given this environment, the power supply is exposed to extreme input conditions. It is desirable to design the power supply capable of withstanding wide AC input conditions. Another advantage is that the rectifier unit will keep the battery charged so that the battery will have long life. This thesis is aimed at designing a 1400W (56V/25A) telecom power supply, keeping in view of the issues expressed above. The aim is to design a Switched Mode Rectifier (SMR) that tolerate wide input voltage variations (90Vac to 300Vac). In addition, the design covers unity input power factor, high efficiency (> 90%), high power density ( ), parallel operation and low cost ( ). Chapter 1 of this thesis covers the context and motivation of the work. Chapter 2 presents the design issues pertaining to power supplies. The normalized description of the power converters is presented. Such a description enables one to compare several circuit topologies in order to make effective design decisions. In a similar way the effectiveness of the switches and mgnetics are presented to enable design decisions in the output stage of the rectifier. Chapter 3 presents the design of the 1400W telecom power supply, keeping in view of the stated specifications. The performance results of the converter are presented in Chapter 4. All the design goals have been met. The design exercise has also given insights into possible further improvements. Contributions from this work and course of future development work are indicated in the concluding chapter.

Studies on ac losses in superconductors have been a subject of great interest for a long time not only as an important topic in fundamental science, but also as a basic requirement for the application of superconductors. A proper understanding of the mechanisms of ac losses and their quantitative knowledge is an essential requirement for any application. Such studies not only yield information on the material parameters crucial for applications but can also provide a test for any possible microscopic theory of superconductivity. The main focus of the current thesis is to understand the mechanisms of ac losses in superconductors and to gain more knowledge on the ac dissipative behavior of type II superconductors. In this thesis we report our investigations on the ac losses in certain type II superconductors at different ranges of frequency through different experimental techniques. We have investigated the ac losses that arise in high Tc superconducting single crystals at rf frequency (8 MHz) using a simple LC oscillator technique. The result shows a surprising ac dissipation behavior in which the loss in the superconducting state is more than the normal state loss. Even though the superconducting state is defined as the zero resistive state, this is true only for dc transport. The ac resistivity studies have been made also on high Tc polycrystalline samples using the standard four-probe technique using a lock-in amplifier (100 kHz). The result shows different ac resistive behavior for samples with different microstructures. Non-resonant microwave absorption (NRMA) studies in MgB2 thin films is reported for the first time. The experiment has been performed using a continuous wave X band EPR spectrometer. The recorded signals give information on the ac losses that occurs at microwave frequency (9.43 GHz). The effects of ac magnetic field on the superconductors have been investigated through a dc four-probe resistivity measurements in the presence of an ac field of different magnitudes applied at different frequencies. Also a simple experimental technique based on the concept of kinetic inductance designed to study the ac losses that arise due to vortex motion is reported. In the following a chapter-wise summary of the thesis is presented.m Chapter 1 surveys the related literature on experimental and theoretical reports on ac losses in superconductors. In this chapter a brief introduction to superconductors is given with an emphasis on the high Tc superconductors. The superconducting materials studied in the thesis are described in detail along with their superconducting parameters and the form of the specimen. The origins of ac losses are discussed with various models proposed so far to explain the ac losses in superconductors. Since most of the ac losses reported in this thesis arise due to the Josephson junctions and vortex motion, they are discussed in detail. The occurrence of Josephson junctions and the various models used to describe the junctions’ characteristics are discussed. The formation of vortices their various forms in layered superconductors and the mechanisms of flux flow and flux creep are discussed. Chapter 2 describes the studies on ac losses in superconducting Bi2Sr2CaCu2O8 single crystals [1,2]. Generally in the superconducting state the dissipation is expected to be less compared with that in the normal state. However, we observe that the ac losses in the superconducting state are larger than the normal state losses. In this chapter we report on the ac losses in superconducting Bi2Sr2CaCu2O8 single crystals at radio frequencies determined from direct measurement of the absorbed power using an rf oscillator [3]. The ac response of Bi2Sr2CaCu2O8 single crystals is investigated as a function of temperature from the measured shift in current and the frequency of the oscillator. The studies are carried out at different rf amplitudes by varying the supply voltage to the oscillator circuit. To understand the magnetic field dependent behavior of ac losses, studies have been performed in the presence of magnetic field of various magnitudes applied parallel to the c-axis of the crystal. In the presence of the magnetic field two peaks are observed in ac losses in the superconducting state as a function of temperature. The presence of the peaks and their behavior are studied in detail by varying the orientation of the applied field with respect to the c-axis of the crystal. The results are discussed in terms of a new model proposed recently by us [4], which explains ac losses as a consequence of cumulative effect of the energy spent in repetitive decoupling of the Josephson junctions and in terms of Lorentz force driven motion of vortices. In Chapter 3, we discuss the ac resistivity behavior of the polycrystalline superconducting samples with different microstructures. Measurement of resistivity is the basic characterization method not only for superconductors but for any material. The superconducting state is defined as the zero resistive state; but this statement is true only for dc and not for ac. The presence of ac resistance in superconductors leads to losses. In the present work we report on the behavior of ac resistance in the superconductors. The application of a magnetic field and the variation of temperature alter the AC penetration depth of the superconducting sample, which in turn changes the AC impedance associated with it. In this chapter we report the results on the complex AC conductivity that has been measured in two types of polycrystalline YBa2Cu3O7 samples at frequencies starting from 100 Hz to 100 kHz and at temperatures from 10 K to 300 K. In the first pellet which is sintered, the possibility of presence of extrinsic Josephson junctions is less, but a large number of Josephson junctions is present in the second non-sintered pellet. In general it is expected that the AC or the DC resistivity in superconductors should decrease below Tc. In the case of DC resistivity the value of resistance goes exactly to zero and in the case of AC resistivity it keeps on decreasing towards zero with decreasing temperature. But surprisingly we find that in superconducting samples with Josephson junctions, the AC resistivity drops very close to zero at the critical temperature and instead of decreasing it increases slowly with decreasing temperature below the critical temperature. This property is also strongly dependent on the applied AC frequency. Investigation of the above phenomenon gives information regarding the contribution of JJ decoupling towards the AC resistivity of superconducting samples. The observed ac resistive behavior is well fitted with the Ambegaokar-Baratoff model for temperature dependence of critical current in the Josephson junction. In Chapter 4, the possibility of the presence of weak links in the intermetallic superconductor MgB2 is reported. The role of weak links in superconductors has been studied for a long time. Understanding the behavior of weak links has great importance for the applications of superconductors. Presence of weak links in high Tc materials due to its insulating grain boundaries limits the application potential of those materials. These weak links lead to lower critical current density and lower critical field of superconductors and lead to losses. The discovery of superconductivity in the simple intermetallic compound MgB2 has created a lot of interest from both application aspects and of fundamental science. MgB2 differs from high Tc materials and is considered as a potential candidate for applications, because of its high critical current density which arises due to the absence of weak links in MgB2. Absence of weak links is reported in most of the MgB2 literature and only in a very few studies possibility of the presence of weak links is reported. Here, our NRMA studies on the MgB2 thin films show the presence of weak links [5]. NRMA is a highly sensitive, non-invasive technique, which has proven to be a valuable tool for detecting weak links in superconductors and their characterization [6]. In this technique the sample is studied using a continuous wave electron paramagnetic resonance (EPR) spectrometer, by recording the magnetic field dependence of the power absorption. The NRMA studies on the MgB2 thin film shows the presence of weak links and hysteresis in the signal. The origin of weak links is discussed as being due to the presence of oxygen in the grain boundaries. The hysteresis appears because of remnant magnetization and due to the pinning of flux lines when there is a change in the sweeping field direction. The NRMA studies are carried out as a function of temperature, modulation field, microwave power and the scan range and the results are reported in this Chapter. In chapter 5 we report on the resistive behavior of superconducting MgB2 film in the presence of an ac field using a novel technique. In this simple technique the resistive measurements are done using the general four-probe method, but a coil is wound over the sample and connected to an ac source to generate the ac field. The resistivity measurements are carried out as a function of temperature, amplitude and the frequency of ac field. The ac field shifts the Tc towards lower temperature and increases the broadening in transition from normal to superconducting state. In the absence of Lorentz force due to the parallel orientation of ac field with the transport current, we find that Josephson junction decoupling is one of the main origins of resistivity. The results are compared with the resistive behavior of YBCO film. The epitaxial YBCO film which is free from weak links shows a different frequency dependent resistive behavior, which is explained in terms of flux-creep. In the MgB2 film the studies are carried out in the presence of a dc field that is applied perpendicular to direction of transport current in the film along with the presence and the absence of the ac field. The studies show that in superconductors the presence of ac field leads to more loss than that of dc field. Chapter 6 describes a simple experimental technique using the property of kinetic inductance to measure the vortex resistivity arising from the ac current. Since the discovery of the superconductors much attention has been given to the dynamics of the vortices because of their importance from both scientific and application point of view. When a magnetic field of amplitude more than Hc1 is applied the type II superconductors enter in to the ‘mixed state’ due to the presence of vortices. In the presence of a current, the vortices experience Lorentz force of magnitude F = J x B normal to the current and the field. The vortices move under the influence of the Lorentz force along its direction which leads to resistivity. The electric field generated by the vortex movement has two components, one acting along the current direction and the other normal to the current direction. But most of the vortex resistivity measurements are carried out either in the presence of high magnetic field or at temperatures closer to Tc due to the limitation of experimental techniques. In this chapter we are reporting a simple experimental technique to measure vortex resistivity with very high resolution even at low temperatures and fields based on the concept of kinetic inductance. Kinetic inductance is the property which arises mostly in superconductors due to the inertial mass of the charge carriers. In our measurement kinetic inductance is measured through a simple four-probe ac impedance technique, which is more commonly used for measuring resistivity. The penetration depth due to vortices is related to their resistivity and from the relation between the measured kinetic inductance and penetration depth vortex resistivity is calculated. In this report we discuss the experimental setup, principle of the method and present the results of our measurements carried out on YBa2Cu3O7 thin films.

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現今許多網路商店或電子商務將產品銷售給消費者的過程中，皆使用推薦系統的幫助來提高銷售量。如亞馬遜公司(Amazon)、Netflix，深入了解顧客的使用習慣，建構專屬的推薦系統並進行個性化的推薦商品給每一位顧客。 推薦系統應用的技術分為協同過濾和內容過濾兩大類，本研究旨在探討協同過濾推薦系統中潛在因子模型方法，利用矩陣分解法找出評分矩陣。在Koren等人(2009)中，將矩陣分解法的演算法大致分為兩種，隨機梯度下降法(Stochastic gradient descent)與交替最小平方法(Alternating least squares)。本研究主要研究目的有三項，一為比較交替最小平方法與隨機梯度下降法的預測能力，二為兩種矩陣分解演算法在加入偏誤項後的表現，三為先完成交替最小平方法與隨機梯度下降法，以其預測值對原始資料之遺失值進行資料插補，再利用奇異值分解法對完整資料做矩陣分解，觀察其前後方法的差異。 研究結果顯示，隨機梯度下降法所需的運算時間比交替最小平方法所需的運算時間少。另外，完成兩種矩陣分解演算法後，將預測值插補遺失值，進行奇異值分解的結果也顯示預測能力有提升。 / Recommender system has been largely used by Internet companies such Amazon and Netflix to make recommendations for Internet users. Techniques for recommender systems can be divided into content filtering approach and collaborative filtering approach. Matrix factorization is a popular method for collaborative filtering approach. It minimizes the object function through stochastic gradient descent and alternating least squares. This thesis has three goals. First, we compare the alternating least squares method and stochastic gradient descent method. Secondly, we compare the performance of matrix factorization method with and without the bias term. Thirdly, we combine singular value decomposition and matrix factorization. As expected, we found the stochastic gradient descent takes less time than the alternating least squares method, and the the matrix factorization method with bias term gives more accurate prediction. We also found that combining singular value decomposition with matrix factorization can improve the predictive accuracy.