The objective of this thesis is to provide a quick process to estimate iron losses of the electric machines with various structures that employ electromagnetic steels in their designs. Due to non-uniform distributed operational magnetic flux densities resulted from the machine structures, the iron losses of machines can not be properly estimated. The aim of the scheme is to modify the deviations among the measurements and the calculations. At first, several standardized steel modules that can be used to assemble the machine structures are established, then a test-bed with closed magnetic path to supply operational magnetic field inside those electric machines is constructed. To calculate the iron loss of each module, the averaged flux densities for each area of the module are measured by needle probe method, and the corresponding magnetic field intensities are calculated from Jiles and Atherton (J-A) model hysteresis model. Finally, the iron loss datasheets for each module are constructed by these measurements, and the iron losses of machines are estimated through assembling the modules. In this thesis, a switched-reluctance machine (SRM) is selected for assessment comparisons, and its iron loss can be calculated through datasheets according to the machine structure. It is believed that the findings of this study can provide a valuable reference and a reliable process in motor designing and manufacturing.

The probe method (PM) is a learning model that equips students with essential learning strategies and skills so they can be successful and competitive in a highly diverse technological global workforce. Although research indicates this learning model was successful at the elementary school level with improving students' motivation to learn, their critical thinking skills, and their ability to solve complex problems, little research has examined the impact of this method at the high school level for students who participated in a career and technical education (CTE) program. The purpose of this qualitative case study was to fill a gap in knowledge about the role and function of the PM on high school students' motivation to learn and their critical thinking skills in a CTE program. Guided by the conceptual framework of constructivism, data were collected through surveys, reflective journals, interviews with 17 students, and a teacher interview. Data were analyzed through descriptive and content analysis using open coding to determine what active learning was taking place, whether authentic project-based and problem-based learning strategies were implemented, and what 21st century workforce skills were being taught. Findings indicated that the PM had a positive impact on high school students' motivation to learn and their ability to think critically in a CTE program. This study supports positive social change by providing high school CTE teachers with a valuable learning model that infuses reflective thought, collaboration, communication, problem solving, and critical thinking into the learning process while at the same time motivating students to learn.

Titano dioksidas, pasižymintis unikaliomis fizikinėmis bei cheminėmis savybėmis, yra gerai žinoma, plačiai naudojama bei tyrinėjama medžiaga. Tiriant TiO2 elektrines savybes, galima gauti informacijos, kokios naujos medžiagos fazės formuojasi plonasluoksnėse dangose. Elektrinė titano dioksido varža priklauso nuo bandinio stechiometriškumo, nusakančio vyraujančius defektus bei laidumo tipą. Siekiant gauti norimų savybių plonasluoksnes dangas, būtina atsižvelgti į bandinių paruošimo ir gamybos procesus. Bandinių nusodinimui naudojama vakuuminė užnešimo technika leidžia kontroliuoti procesus, lemiančius dangos savybes. Šiame darbe buvo atliekama literatūros analizė apie elektrines TiO2 savybes bei įvairių faktorių įtaką šio parametro kitimui. Taip pat atkreiptas dėmesys į plonasluoksnių struktūrų nusodinimą, naudojant fizikinį dangų nusodinimą iš garų fazės (PVD). Paviršinės TiO2 varžos tyrimas buvo atliekamas panaudojant 4 zondų metodą. / Titanium dioxide is well known, widely used and investigated material that shows unique physical and chemical properties. Investigations of TiO2 electrical conductivity gives an information about the new phases formed in thin films. Surface resistance of titanium dioxide depends on sample‘s stoichiometry and it shows predominant defects and type of conductivity being in the thin film structure. It is very important to pay an attention into processes of sample‘s preparation and formation technique in order to get thin films with desirable properties. Thin films were formed using vacuum deposition technique. There has been done a scientific literature survey in order to know the main factors that causes changes of TiO2 electrical properties in this work. An attention was paid into deposition of thin film structures using physical vapor deposition (PVD) technique as well. Measurements of TiO2 surface resistance were done using four probe method.

This thesis proposed a near-field electromagnetic interference measurement framework to obtain sensitivity and spatial resolution of the characteristic parameters of magnetic probe based on International Electrotechnical Commission proposed for integrated circuits electromagnetic radiation measurement standards IEC 61967-6 : magnetic probe method. Using cross-coupled planar microwave bandpass filter which is realized by glass fiber board (FR4) for near-field measurement and electromagnetic simulation in comparsion. Nowadays, integrated circuits has become an important source of energy of overall electromagnetic interference in electronic systems. Finally, do near-field scanning measurement for a 64-pin wire-bond quad flat nonlead (WB-QFN) package and the voltage-controlled oscillator chip in 0.18 £gm CMOS technology by using high scanning resolution of microprobe. Then observes the chip-level and package-level electromagnetic interference, and achieve chip-level of near-field electromagnetic interference measurement techniques.

Tato diplomová práce se věnuje výrobě vrstev grafitu/grafenu a meření jejich transportních vlastností v závislosti na relativní vlhkosti. Grafenové šupinky byly nanášeny pomocí mechanického odlupování . Pro kontaktování grafenových šupinek byla využita elektronová litografie a na pozorování byly využity optická mikroskopie, mikroskopie atomárních sil a elektronová mikroskopie. V práci jsou popsány jednotlivé kroky výroby, analýzy a měření transportních vlastností nanesených grafenových šupinek.

Este trabalho apresenta o estudo, a implementação e a caracterização de transdutores compostos por uma estrutura formada por grades de Bragg (FBG, Fiber Bragg Gratings) e grades de período longo (LPG, Long Period Gratings) em fibra óptica com cobertura metálica autoaquecida para medição da condutividade térmica e da difusividade térmica de materiais baseado no método do fio quente (HWM, Hot-Wire Method) convencional. O autoaquecimento da fibra óptica do dispositivo desenvolvido neste trabalho é provocado pela luz de espectro infravermelho injetada por um laser de bombeamento, que é espalhada por uma LPG e absorvida por um filme fino metálico depositado na superfície da fibra. Os transdutores apresentados são compactos, simples, robustos e imunes a interferências eletromagnéticas. O arranjo experimental utilizando o dispositivo híbrido LPG-FBG foi capaz de medir as condutividades térmicas do ar atmosférico e da água comum com precisões de 27% e 14%, respectivamente. Foram identificados vários fatores que afetam a precisão e a exatidão das medidas realizadas, sendo propostas diversas formas de correções de modo a melhorar o desempenho do arranjo. Foi demonstrada com sucesso a viabilidade da aplicação original do arranjo experimental utilizando o dispositivo híbrido LPG-FBG em fibra óptica autoaquecida para a medição de propriedades térmicas de fluidos (ar e água). / This work presents the study, implementation, and characterization of transducers composed of a structure formed by Fiber Bragg Gratings (FBG) and Long Period Gratings (LPG) in optical fiber with self-heating coverage for measurement of thermal conductivity and thermal diffusivity of materials based on the Hot-Wire Method (HWM). The self-heating fiber optic device developed in this work is caused by the light of infrared spectrum injected by a pumping laser, which is spread by an LPG and absorbed by a thin metallic film deposited on the surface of the fiber. The transducers are compact, simple, robust and immune to electromagnetic interference. The experimental arrangement using the optical fiber sensor based on LPG-FBG hybrid structure was able to measure the thermal conductivity of atmospheric air and water with accuracies of 27% and 14%, respectively. Several factors were identified that affect the precision and the accuracy of the measures carried out, whereby various forms of corrections are being proposed to improve overall performance. The viability of the original application of the experimental arrangement using the LPG-FBG hybrid device in self-heating optical fiber for the measurement of thermal properties of fluids (air and water) has been successfully demonstrated.

Este trabalho apresenta o estudo, a implementação e a caracterização de transdutores compostos por uma estrutura formada por grades de Bragg (FBG, Fiber Bragg Gratings) e grades de período longo (LPG, Long Period Gratings) em fibra óptica com cobertura metálica autoaquecida para medição da condutividade térmica e da difusividade térmica de materiais baseado no método do fio quente (HWM, Hot-Wire Method) convencional. O autoaquecimento da fibra óptica do dispositivo desenvolvido neste trabalho é provocado pela luz de espectro infravermelho injetada por um laser de bombeamento, que é espalhada por uma LPG e absorvida por um filme fino metálico depositado na superfície da fibra. Os transdutores apresentados são compactos, simples, robustos e imunes a interferências eletromagnéticas. O arranjo experimental utilizando o dispositivo híbrido LPG-FBG foi capaz de medir as condutividades térmicas do ar atmosférico e da água comum com precisões de 27% e 14%, respectivamente. Foram identificados vários fatores que afetam a precisão e a exatidão das medidas realizadas, sendo propostas diversas formas de correções de modo a melhorar o desempenho do arranjo. Foi demonstrada com sucesso a viabilidade da aplicação original do arranjo experimental utilizando o dispositivo híbrido LPG-FBG em fibra óptica autoaquecida para a medição de propriedades térmicas de fluidos (ar e água). / This work presents the study, implementation, and characterization of transducers composed of a structure formed by Fiber Bragg Gratings (FBG) and Long Period Gratings (LPG) in optical fiber with self-heating coverage for measurement of thermal conductivity and thermal diffusivity of materials based on the Hot-Wire Method (HWM). The self-heating fiber optic device developed in this work is caused by the light of infrared spectrum injected by a pumping laser, which is spread by an LPG and absorbed by a thin metallic film deposited on the surface of the fiber. The transducers are compact, simple, robust and immune to electromagnetic interference. The experimental arrangement using the optical fiber sensor based on LPG-FBG hybrid structure was able to measure the thermal conductivity of atmospheric air and water with accuracies of 27% and 14%, respectively. Several factors were identified that affect the precision and the accuracy of the measures carried out, whereby various forms of corrections are being proposed to improve overall performance. The viability of the original application of the experimental arrangement using the LPG-FBG hybrid device in self-heating optical fiber for the measurement of thermal properties of fluids (air and water) has been successfully demonstrated.

En la presente memoria se describe el método para la medida de la variación térmica de la resistividad entre 10 y 300 K que hemos puesto a punto en nuestros laboratorios de la Universidad de Cantabria. Dicho método es el de cuatro puntas con corriente alterna y detección síncrona. También se analizan, mediante el método de los elementos finitos, los efectos de la geometría de la muestra y posición de los contactos en la relación entre la resistividad observada experimentalmente y la resistividad real, haciendo hincapié en el caso de muestras anisótropas. Posteriormente aplicamos esta técnica al estudio de diversas series de materiales: 1) Los compuestos RPt que cumplen la Ley de De Gennes y en los que hemos podido determinar los valores de la masa efectiva m* y de la constante de canje. 2) Los compuestos RNi2Si2 en las que se puede observar una relación entre la resistividad magnética y las estructuras magnéticas. 3) Los compuestos CeyLa1-yNixPt1-x, en las que se estudia el efecto Kondo 4) Los amorfos metálicos (Co1-x(Fe5Ni5)x)75Si15B10 en los que se observa un mínimo en la resistividad a bajas temperaturas así como variaciones en lnT, T2 y T a temperaturas bajas, intermedias y altas respectivamente / The present report describes the method for measuring the temperature dependence of the resistivity between 10 and 300 K that we have developed in our laboratories at the University of Cantabria. This is a four-probe method using ac current and synchronous detection. Also it is analyzed, using the finite element method, the effects of the sample geometry and contacts position in the relationship between the real resistivity and resistivity observed experimentally, even in the case of anisotropic samples. Subsequently we apply this technique to the study of different family of materials: 1) RPt compounds which follow the De Gennes Law, allowing us to determine the values of the effective mass m * and exchange constant. 2) The compounds RNi2Si2 in which it is possible to establish a relationship between the magnetic resistivity and the magnetic structures. 3) The compounds CeyLa1-yNixPt1-x, in which we study the Kondo effects. 4) The amorphous Co1-x(Fe5Ni5)x)75Si15B10 metals, in which there is a minimum in the resistivity at low temperatures as well as variations in LnT, T2 and T at low, intermediate and high temperatures respectively.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The petroleum industry produces significant amounts of residues in several of its processes, from the perforation of wells, production, storage, transport and refining, to the distribution of its derivatives. The wastewater generated in the oil extraction step is known as produced water and, when stored in flotation tanks, if generates a residue called oily sludge . In a previous report, carbon-clay composites were obtained from this oily sludge and it was found this the material shows semiconductor properties. Thus, here we aimed to further evaluate the electrical properties of the carbon-clay composites using a home-made four probe apparatus. The carbon-clay composites have been prepared using the pyrolysis conditions reported in the previous study, changing here the precursor granulometry then afterwards characterizing the samples by FTIR, XRD, Raman and SEM. The presence of clays-mineral phases as well as carbon rich phases was evidenced from FTIR spectroscopy. Raman spectra revealed the presence of graphitic crystallites in addition to a disordered carbon matrix. XRD data allowed us to properly identify the mineral phases. SEM images have shown a clear effect of the precursor granulometry on the microstructure of the final pellets. Compact pellets can be expected when using a precursor with smaller particle size. The electrical measurements were accomplished using both a current source especially built for this and alternatively a Keithey 237 electrometer coupled to the four-probe apparatus. Satisfactory current values in terms of stability and reproducibility were obtained with both sources in the range of 640 μA (minimum potential) 37 mA (maximum potential). Applying current values in this range for the carbon-clay composite samples it was possible to confirm their semiconductive properties, since conductivities were found to lie in the range ≈10-4 (Ω*cm)-1. Finally the sample compactness was found to play a significant role in the electrical conductivity since the higher conductivity values were found for more compact samples. / A indústria petrolífera produz quantidades significativas de resíduos em vários dos seus processos, desde a perfuração de poços até a distribuição de seus derivados. Nesse ambiente industrial surge a chamada água produzida, que ao ficar em tanques de flotação, gera um resíduo chamado de borra de petróleo . A partir de uma observação preliminar, realizada por Andrade et al, do compósito carbono-argila, utilizando a espectroscopia de impedância eletroquímica, foi possível identificar que o material em estudo é um semicondutor. Desta maneira, surgiu o interesse de estudar com mais profundidade as características elétricas do mesmo. O objetivo deste trabalho é realizar um estudo das propriedades elétricas do compósito, destacando seus parâmetros principais como condutividade e resistividade elétricas, pelo método de quatro pontas e caracterizar a borra de petróleo gerada no tratamento de água produzida. A borra de petróleo foi seca inicialmente por 48 horas a 110ºC, foram feitas pastilhas com material peneirado a granulometrias diferentes e depois sinterizadas sob atmosfera inerte de nitrogênio, até 800ºC com isoterma de 2h. Em seguida, foi realizada a montagem do aparato de quatro terminais utilizando eletrodos de latão e de platina, para medição de resistividade elétrica do material e a montagem de uma fonte de corrente constante. Através do espectro FTIR, observou-se banda referentes aos estiramento O-H de argilominerais; bandas de resíduos orgânicos; e banda dos componentes minerais. As análises de DRX apresentaram como constituintes a montmorilonita, quartzo, calcita e barita, bem como a cristobalita, ghelenita, anortita e magnetita. O Raman apresentou banda devido à presença de carbono grafite e banda devido à desordem na estrutura do carbono grafite. A análise por MEV apresentou em algumas amostras superfície mais compactada com a presença de grãos e aglomerados. Tanto com a fonte construída, quanto com um eletrômetro obteve-se uma estabilidade de corrente na faixa de 640μA a 37mA. Foi possível comprovar com ambas as medidas que o material em estudo é um material que apresentou um valor de condutividade na faixa da semicondução (≈10-4 Ω.cm)-1.

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