The thesis deals with the study of the influences of selected groups of chemical agents on the stability of PTC ceramics based on BaTiO3. The experimental part includes elaboration of methodology for determination of these influences, their evaluation, including the hypotheses for their description, and evaluation of groups of chemical agents having these influences.

<p>This report describes the construction of a climate-cabinet for testing of HV-cards (High Voltage) produced at VG Scienta. The main part of the report describes all the different components of the cabinet. The most important parts are a PID regulator from Eurotherm model 2408, a solid state contactor (SSC), a thermocouple, a finned resistor from DBK and different fans. The report even includes the connection between components by cable wiring, isolation, grounding, fuses and shaping of metal goods.</p><p>As the cabinet also communicates with a computer, the report includes the solution of the data communication using the software iTools from Eurotherm. The communication part includes information about a converter that converts EIA422 to USB.</p><p>The cabinet was produced at a company, called VG Scienta, in Uppsala during the spring 2010. The construction of an additional climate-cabinet was necessary because during the last year Scientas productivity increased, and it was important for the company to be able to manage the testing of an increased number of electronics.</p><p>Which solution is best for the heating of a cabinet? How does the communication work between a PC and a Eurotherm 2408 regulator? How to detect the temperature inside of the cabinet? These are some of the topics which are discussed.</p><p>The finished cabinet resembled the old cabinet in many ways. The difference between them is that the later one allows the testing of twice as many HV-cards, in an even more flexible way by the communication between the regulator and the computer. It means that the regulator parameters can be set continually and by programming it is possible to save the settings, the parameters and the curves.</p>

This report describes the construction of a climate-cabinet for testing of HV-cards (High Voltage) produced at VG Scienta. The main part of the report describes all the different components of the cabinet. The most important parts are a PID regulator from Eurotherm model 2408, a solid state contactor (SSC), a thermocouple, a finned resistor from DBK and different fans. The report even includes the connection between components by cable wiring, isolation, grounding, fuses and shaping of metal goods. As the cabinet also communicates with a computer, the report includes the solution of the data communication using the software iTools from Eurotherm. The communication part includes information about a converter that converts EIA422 to USB. The cabinet was produced at a company, called VG Scienta, in Uppsala during the spring 2010. The construction of an additional climate-cabinet was necessary because during the last year Scientas productivity increased, and it was important for the company to be able to manage the testing of an increased number of electronics. Which solution is best for the heating of a cabinet? How does the communication work between a PC and a Eurotherm 2408 regulator? How to detect the temperature inside of the cabinet? These are some of the topics which are discussed. The finished cabinet resembled the old cabinet in many ways. The difference between them is that the later one allows the testing of twice as many HV-cards, in an even more flexible way by the communication between the regulator and the computer. It means that the regulator parameters can be set continually and by programming it is possible to save the settings, the parameters and the curves.

As rotas sintéticas para obtenção de cloridrato de petidina foram avaliadas sob o ponto de vista tecnológico, material e de segurança com o objetivo de adaptar a produção a reatores multipropósito. O aperfeiçoamento de técnicas antigas e introdução de técnicas recentes como a catálise de transferência de fase viabilizaram o projeto. / The synthetic routes for obtention of pethidine hydrochloride were evaluated under technologycal, material and safety aproach, in order to be able to manufacturing in multipurpose reactors. The improvment of old techniques and introduction of recents advances like phase transfer catalysis \"P.T.C.\" making it a available presentation.

As rotas sintéticas para obtenção de cloridrato de petidina foram avaliadas sob o ponto de vista tecnológico, material e de segurança com o objetivo de adaptar a produção a reatores multipropósito. O aperfeiçoamento de técnicas antigas e introdução de técnicas recentes como a catálise de transferência de fase viabilizaram o projeto. / The synthetic routes for obtention of pethidine hydrochloride were evaluated under technologycal, material and safety aproach, in order to be able to manufacturing in multipurpose reactors. The improvment of old techniques and introduction of recents advances like phase transfer catalysis \"P.T.C.\" making it a available presentation.

Made available in DSpace on 2016-08-17T14:52:51Z (GMT). No. of bitstreams: 1 Michel Valenca Gabriel.pdf: 465513 bytes, checksum: 942d92f812d9d94a2f9910b710ac55f2 (MD5) Previous issue date: 2004-01-30 / In this work we present a study on the sensitivity of anemometers based on thermoresistive sensors heated to a constant temperature. The configurations that makes the thermoresistive sensor heated to a constant temperature are composed of a Wheatstone bridge using a feedback operational amplifier. The substitution measurement method is used, where an electrical quantity, the operational amplifier output voltage, varies in accordance to the variation of the quantity of interest, in such a way that the electrical quantity compensates the effect of the former in the sensor. In our case, the quantity to be measured is the speed of the wind and the quantity of substitution is operational amplifier output voltage. Studies were carried out considering two types of sensors, the metallic PTC and the thermistor NTC. An analysis of the measurement circuits was carried out for each sensor type, taking into account the constants and variables that influence the measurement process. For these circuits, simulation results are presented which make possible to evaluate the measurement system behavior. An analysis of the sensitivity of the measurement circuits output voltage with respect to the wind speed is also carried out. This analysis made possible the development of a procedure for determining the operation point for the NTC-based circuit that yields the maximum sensitivity. From the analysis of the measurement configurations sensitivity, it was observed that the NTC-based configuration presents higher sensitivity compared to the PTC-based configuration, for relatively low operating temperatures, above the ambient temperature. The equivalent sensitivity for the PTC-based configuration occurs only for temperatures much higher than that for achieving the maximum sensitivity for the NTC. This characteristic can be used for implementing anemometers that operates at a temperature much closer to the ambient temperature. / Neste trabalho apresentamos um estudo sobre a sensibilidade de anemômetros baseados em sensores termo-resistivos aquecidos a temperatura constante. A configuração que faz com que o sensor termo-resistivo seja aquecido a uma temperatura constante é composta de uma ponte de Wheatstone realimentada usando um amplificador operacional [1]. O método de medição utilizado é o de substituição, em que uma grandeza elétrica, a tensão de saída do amplificador operacional, varia de acordo com a variação da grandeza de interesse, de forma a compensar seu efeito no sensor. Neste caso, a grandeza a ser medida é a velocidade do vento e a grandeza de substituição é a tensão de saída do amplificador operacional. Foram feitos estudos considerandos dois tipos de sensores, o PTC metálico e o termistor NTC. Faz-se uma análise dos circuitos de medição para cada tipo de sensor, levando em conta as constantes e as variáveis que interferem no processo de medição. Para tais circuitos são apresentados resultados de simulações em computador que nos possibilitaram avaliar o comportamento do sistema de medição. Para os circuitos de medição, faz-se uma análise da sensibilidade da tensão de saída do amplificador operacional com relação à velocidade do vento. Essa análise possibilitou desenvolvimento de um método para cálculo do ponto de maior sensibilidade e ponto de operação do circuito baseado no NTC. Observou-se que a configuração com NTC apresenta uma maior sensibilidade do que a configuração com PTC para temperaturas de operação do sensor relativamente baixas, mas acima da temperatura ambiente. A sensibilidade equivalente da configuração com o PTC ocorre para temperaturas bem acima do ponto de máxima sensibilidade do NTC. Essa característica pode ser aproveitada para implementações de anemômetros aquecidos que operam com temperaturas mais próximas da temperatura ambiente.

Concentrated Solar Power (CSP) also known as concentrated solar thermal is the systematic act of using mirrors and lenses to concentrate direct sunlight to a specific focal point so that solar radiation can be converted into useful electrical energy. The genesis of CSP technology dates back from the 1800s, when August Mouchout used a Parabolic Trough Collector (PTC) to produce steam. CSPs are known to have different types of collector technology which include the enclosed trough, solar power tower, fresnel reflectors, dish stirling, and parabolic trough collector. It has been established that a Parabolic Trough collector (PTC) is the most developed form of technology that a concentrated solar power plant can utilize to harness the energy of the sun. PTCs are commonly used by large scale plants to collect a large amount of solar radiation and incorporate it into their many functions. PTCs are energy reactors which enables heat exchange between solar energy and a transport fluid medium. They are ‘parabolic’ in shape, consist of an absorption tube located at the focal concentrating point, a bearing structure, and a shiny reflector surface. PTCs can either have a one or two-axis tracking system. PTCs with a two-axis tracking system are more efficient because of their zero-incidence angle, however they are generally more costly to maintain and have higher thermal losses involved. It is highly imperative that the PTC reflector surface has constant good reflectance as this is where the Direct Normal Irradiance (DNI) is absorbed and emitted to the focal line of the PTC. Strict design requirements such as high UV reflectance, corrosion resistance and weather resistance are necessary. Past research has proven that aluminium is a good choice of material because of its low cost and high reflective properties. A PTC system can be applied in different areas according temperature output requirements. For lower temperature requirement (100°C- 250°C) they are used for domestic heating, heat driven refrigeration systems and air conditioning units. For higher temperature requirement (300°C- 400°C), they are used in CSP plants arranged in array form with multiple PTC units connected together ultimately forming a PTC plant. Generally, all CSP plants are located in dessert arid regions where the exposure to sunlight is hardly hindered. Maximum exposure to sunlight is necessary for a CSP plant as the solar energy that reaches the earth is about 170 trillion kWH and the major aim of all CSP plants is to harness as much as possible effectively. In this regard, the reflectivity of mirror facets of a collector unit needs to be kept clean and free of any substance that reduces reflectivity. Due to CSP plant location, dessert storms and sandstorms occur frequently causing sand particles to be deposited on the surface of mirrors. Mirror soling is defined as the deposition of dust particles on mirror facets resulting from particle movement from one region to the mirror. Dust particles can absorb and deflect solar rays that hit the mirror facets limiting reflectivity and limiting the performance output of a CSP plant. Mirror soiling is phenomena that cannot be easily prevented 100% as there are different sizes to particles and one would have to stop the weather and climate altogether. PTC plants as well as other CSP plants experience mirror soiling on a daily basis of their operation. In dealing with this problem, plants have employed cleaning methods that commonly utilize a large volume of water which gives favourable results in trying to maintain high reflectivity. However, for a location that is dry and arid, it is not economical to carry on using water where it is a considerable finite resource. To minimize water usage in handling this problem to a significant number or nil, researchers have tried automated novel methods, water saving methods and dust prevention methods. A dust prevention method that has proven to reduce mirror soiling to a significant number is the installation of a wind barrier. It has been numerically proven and validated that a wind barrier, placed in the prevailing wind direction, can deflect dust particles away from a defined mirror location. The presented thesis and research aim to re-introduce porous barriers and non-porous barriers as a simple economical practical approach that can minimize mirror soiling and present it as an alternative solution that lessens the volume of water used to clean collector facets. The thesis is purely simulation-based and incorporates particle mechanics and computational fluid dynamic (CFD) to show results and performance of wind barriers ultimately deriving an optimum candidate that can be manufactured and used in CSP plants. The study used ANSYS 2019 packages as the simulation tool to perform simulations and optimization procedures. Results showed that an optimum porous barrier has the capability to increase a CSP plant efficiency by a significant percentage. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2021. / Mechanical and Aeronautical Engineering / MEng (Mechanical Engineering) / Unrestricted

No description available.

Activating mutations of genes coding for two different tyrosine kinase receptor, either RET or NTRK1 (also named TRKA), as well as of RAS or BRAF gene are associated with human thyroid papillary carcinoma (PTC). RET or NTRK1 protooncogene encodes a cell-surface transmembrane tyrosine kinase receptor with nerve growth factor as its lignand. Oncogenic potential of these two genes in thyrocytes results from replacement of their 5' portion by regulatory parts of other genes, leading to constitutive activation of their tyrosine kinase activity. The four reported oncogenic rearrangements of NTRK1 (TRK) are the consequences of fusion of its tyrosine kinase domain with one of the three genes (TPM3 gene, TPR gene, TFG gene). In our previous study, a PTC sample was found to express the NTRK1 tyrosine kinase domain without harboring NTRK1 rearrangement. We, therefore, assumed that there might have a novel NTRK1 rearrangement in this sample. 5¡¦RACE strategy was employed to clone the unknown 5¡¦end. Sequence of the cloned DNA fragment demonstrated that it is an aberrant transcription product containing an unspliced intron 9. In addition, the variant of NTRK1 wild type termed TRKA¢¹, which lacks exon 9, was also detected in this particular specimen. We conclude that amplification of TK domain of NTRK1 may serve as a rapid screening method for the presence of NTRK1-related transcript in PTCs. Mutations of the BRAF protein serine/threonine kinase gene have recently been identified in a variety of human cancers, especially in melanoma and papillary thyroid carcinomas. Among benign and malignant thyroid tumors, BRAF V599E mutations were reported to be restricted to papillary carcinomas. In this study, we analyzed mutations of BRAF in conjunction with our previous studies on RAS, RET rearrangement and NTRK1 rearrangement in PTCs to investigate genetic alterations in the RAS/RAF/MEK/MAPK kinase pathway. BRAF V599E mutations were detected in 49 of 105 (47%) PTCs but not in other type of thyroid tumor. There was no overlap between papillary carcinomas harboring RET rearrangement, NTRK1 rearrangement and BRAF mutations. Correlation between BRAF mutations and various clinicopathological parameters in 101 papillary carcinomas did not reveal any association with age, sex, tumor size, cervical lymph node metastasis, extrathyroidal extension, distant metastases and clinical stage. We conclude that BRAF mutations are restricted to papillary carcinomas in thyroid tumor. The overall frequencies in our study are in line with data previously reported. In Taiwan, BRAF mutation is the most prevalent oncogene in papillary thyroid carcinomas so far identified.

No description available.