Partial Discharge in Electronic Equipments

Tato disertační práce se věnuje studiu částečných výbojů (PD) způsobených poklesem spolehlivosti a životnosti elektronických zařízení a systémů. Diagnostika PD je dnes známá metoda pro vysoké napětí u vysoko-výkonných zařízení. V případě elektronických zařízení PD testování není ale běžně používáná metoda, přestože je zde také potenciál pro vysoké elektrické zatížení vzhledem k velmi krátké vzdálenosti. Tato práce je zaměřena na vyšetřování PD činnosti u elektronických zařízení. Bylo navrženo a provedeno pracoviště pro diagnostiku PD v elektronických zařízeních. Pracovní frekvence se pohybuje od několika stovek Hz až 100 kHz. Maximální amplituda PD testovaného napětí je vyšší než 10 kV. Navzdory jednoduché konstrukci toto zařízení přináší vysokou spolehlivost měření. Více než 300 PD testů bylo provedeno na různých elektronických zařízeních a elektronických součástí,např. na planárních transformátorech a elektronických komponentách používaných při vysoko-napěťových měničíchThis dissertation thesis is devoted to study of partial discharge (PD) caused decrease of reliability and lifetime of electronic equipments and systems. PD diagnostic is nowadays well known method for high voltage high power equipments but in case of electronic devices PD testing it is not used routinely despite that there is also a potential for high electric load due to extremely short distances. The risk of PD caused failure is here extremely high because of high working frequency and consequently high repetition rate of PD events. Therefore, this work is focused on investigation of PD activity in electronic equipments. The workplace for PD diagnostic in electronic devices based on switched power supply was designed and made. Working frequency ranges from several hundreds of Hertz up to 100 kHz. The maximal amplitude of PD testing voltage is higher than 10 kV. Despite the simple design this equipment brings high repeatability and reliability of measurement. More than 300 PD tests were made on different electronic devices and electronic components, on planar transformers, and on components for voltage gate drivers for use in high voltage power converters. Possibilities of PD tools in investigation and engineering ofd insulation systems were demonstrated.

Implementation of novel methods of global and nonsmooth optimization : GANSO programming library

We discuss the implementation of a number of modern methods of global and nonsmooth continuous optimization, based on the ideas of Rubinov, in a programming library GANSO. GANSO implements the derivative-free bundle method, the extended cutting angle method, dynamical system-based optimization and their various combinations and heuristics. We outline the main ideas behind each method, and report on the interfacing with Matlab and Maple packages. <br /

Comparative Analysis of Diffusion Metallization Coatings Applied on Steel Parts

In this paper the positive and negative aspects of diffusion metallization of steels were reviewed. It was shown that at high heating temperatures and prolonged exposure under these temperatures, steels show a tendency to enlarge austenitic grain. Overheating can occur at high exposure temperatures (T&gt;1000ᵒC), which can be rectified by repeated heating however if burning of the steel microstructure occurs, it cannot be corrected. Given these circumstances, when assigning diffusion metallization modes, it is necessary to consider the factor of overheating or burning of steel in the process of exposure to high temperatures. To avoid this phenomenon, it is recommended to use alternative low-temperature processes of diffusion saturation of steels. Nitriding, nitro-cementation, gas-thermal spraying of the surface of steels are shown as such examples. It was suggested that these processes in comparison with diffusion metallization are more promising and acceptable for the restoration of worn surfaces of steels in the manufacture of parts of specialized equipment. Given that the parts of specialized equipment work in extreme conditions, repeated high-temperature heating of these steels is not recommended.To overcome the shortcomings of the diffusion metallization, the most frequently used coatings are applied by CVD, thermal spray, and cloth cladding techniques. As an alternative promising solution, the development of innovative methods of diffusion saturation, like an ion plantation of atoms on a relatively cold surface of the part could also be considered. It is shown that diffusion metallization is most acceptable for saturation of the surface of non-ferrous metals and alloys with the hardest and wear-resistant compounds

Predicting and controlling the dynamics of infectious diseases

This paper introduces a new optimal control model to describe and control the dynamics of infectious diseases. In the present model, the average time of isolation (i.e. hospitalization) of infectious population is the main time-dependent parameter that defines the spread of infection. All the preventive measures aim to decrease the average time of isolation under given constraints

Dynamics of Ebola epidemics in West Africa 2014

This paper investigates the dynamics of Ebola virus transmission in West Africa during 2014. The reproduction numbers for the total period of epidemic and for different consequent time intervals are estimated based on a newly suggested linear model. It contains one major variable - the average time of infectiousness (time from onset to hospitalization) that is considered as a parameter for controlling the future dynamics of epidemics. Numerical implementations are carried out on data collected from three countries Guinea, Sierra Leone and Liberia as well as the total data collected worldwide. Predictions are provided by considering different scenarios involving the average times of infectiousness for the next few months and the end of the current epidemic is estimated according to each scenario

Solution of the Synthesis Problem of Boundary Optimal Control of a Rod Cooling Process with a Heat Conductive Viscosity

The problem of synthesis of the boundary optimal control of the cooling process of media with heat conductive viscosity is investigated. In addition to the distributed parameters, the concentrated parameters act on the system. This is due to the fact that the temperature of the external environment is unknown and varies according to a given law. As a result, the process is described by a system of partial differential equations and ordinary differential equations. In this case, heat transfer occurs at the right end of the rod. This complicates the obtaining of a solution of this boundary-value problem in an explicit form. But it is possible to establish the existence and uniqueness of the solution of the corresponding boundary-value problem for concrete admissible controls.The criterion of quality is a quadratic functional and it is required to build control in the form of feedback. First by the Fourier method, the problem under consideration is formulated in an infinite-dimensional phase space. As a result, the problem of synthesis of optimal control in a functional space is obtained. To solve this problem, the dynamic programming method is used. To do this, let's introduce the Bellman functional and obtain the Bellman equation, which this functional satisfies. The solution of this equation allows to find the control parameter in the form of a functional defined on the set of the state function. Further, by introducing the corresponding functions, feedback control is constructed for the original problem. Unlike program control, this allows to influence the behavior of the system at any time, that is, to ensure the self-regulation of the process. However, let's note that the difficulties in solving this problem are connected with the justification of the proposed method. This is established by the investigation of a closed system

Individual Difference Predictors of Creative Ideation

Researchers have long been interested in individual difference variables as predictors of creativity. The focus of most studies has been on the later stages of creativity process through which creative ideas are transformed into tangible forms, but until recently a very limited empirical base existed to answer questions about why some individuals come up with creative ideas more often than others. The present study examined individual difference predictors of creative ideation among high ability undergraduate students and tested the role of well-being as a moderator in explaining these relationships. Three main findings are revealed. First, openness and extraversion were significantly associated with creative ideation, both positively. Second, creative ideation was also predicted by creative personal identity. Third, subjective well-being had both main and moderating effects on creative ideation. It moderated the relationship between creative personal identity and creative ideation

Organization of technology park and its structure at high educational school of Azerbaijan

On the base of international experience of creation of technology park and also an analyze of the stages of its realization in Sumgayit region the common scheme of technology park on the base of the Sumgayit State University is offered. The problems of the scheme of realization of the projects of the scientific-investigation places in the industrial park are considered