117 research outputs found
Wavelets analysis for the fast integration and derivation of a class of signals related to control systems
No full textAdvanced Analysis of Haar Transform-Based Control for DC Motors
No full textA careful analysis of the system formed by a dc motor fed by a chopper has been performed in this work thanks to a sophisticated mathematical apparatus based on Haar transform. Previous mathematical analysis has been conducted through Haar functions in order to establish bases for a reliable and efficient real time control of chopper-motor systems. The tool based on the general framework of wavelets has been improved and better tuned on this specific application. A more accurate comparison of existing methods used to solve differential equations and the Haar domain techniques are presented and critically discussed. Transient conditions during the starting process and duty cycle effects can usefully be examined using such technique, putting into evidence specific characteristics of the chopper-motor system. Examples describing the application of the proposed technique are presented and critically discussed
Analysis of Encryption Key Management Systems: Strengths, Weaknesses, Opportunities, Threats
No full textAs more and more enterprises encrypt data in order to adhere to information security policies and compliance rules, centralized key management is becoming increasingly relevant. Among the many available key management systems, it is difficult to select the one that would suit enterprise needs. To the best of our knowledge, no research to date has been conducted to assist small business in selecting an optimal encryption key manager. Based on studying the small business requirements, we presented the strengths and weaknesses of key management systems and analyzed what opportunities and threats it faces during the implementation. We summarize the results in a SWOT analysis of the five systems by evaluating 20 attributes related to the complexity of implementation, tool's popularity, linked vulnerabilities and technical performance in terms of response time and network usage. We concluded that Hachicorp Vault was determined to be the most suitable system for small businesses. </p
Analysis in a wavelet transformed domain of the lightning return stroke electromagnetic field
No full textSociocultural theory and the practice of teaching historical concepts
No full textLearning awakens a variety of internal developmental processes that are able to operate only when the child is interacting with people in his environment and in cooperation with peers. (Vygotsky, 1978, p. 90) In our teacher education courses, we discuss with the trainee teachers educationally relevant topics from the field of learning theory. One of these topics is the acquisition of historical concepts. Through practical experiences and classroom assignments, the trainee teachers become aware of some of the problems involved in the teaching of concepts. Often, they plan to teach concepts in a straightforward matter-of-fact manner using a transmission model of teaching. As teacher educators, we challenge this idea in order to replace this approach with more effective models. So, with our trainee teachers we discuss how secondary education students can achieve a deeper understanding of concepts. Two basic elements of helping trainee teachers teach for understanding are (1) methods to create powerful learning environments and (2) methods to present the historical subject matter in terms of a meaningful whole. This approach is influenced by a Vygotskian sociocultural theory of teaching and learning. In this perspective the creation of a learning environment can be conceived of as a shared problem space, inviting the students to participate in a process of negotiation and co-construction of knowledge. Lev Vygotsky, the founder of the sociocultural theory, developed a new framework for conceptualizing these educational dialogues, through which students acquire new modes of handling knowledge and solving problems
Determination of the temperature of a dense plasma from a spectral line shift
No full textThe method of maximum spectral line shift proposed by Bardocz, et al, (1966) was successfully applied in the diagnostics of dense plasmas produced by high power pulse discharges. It is pointed out that the effect of the shock wave pressure on the spectral line shift has to be taken into account in order to obtain accurate results with this method for high power discharges. A pressure dependent function was introduced in the expression given by those authors to provide the necessary correction
Heating Tariff System In Donetsk
No full textIn different countries, such as Ukraine and Sweden, there have been differences in the way of administrating the systems which dictate the way of living and the way the societies function. Different approaches have been adopted over the time when it came to setting up the rules for how the state´s vital organizations, such as tax administration, health care, police, army, education system and many others should work and function. The idea in many modern countries is the same, but the ways and procedures can differ a great deal from country to country. This applies to the sphere of district heating services as well. The purpose of this thesis is to gain understand with the help of economic theory why heating tariffs are managed in a country that has had transition from plan economy to market economy the way they are, and how the management of heating tariffs could be improved when taking into account the experience of a country with long established market economy. During field studies performed in Sweden and Ukraine, particularly in the city of Donetsk, a comparative analysis of the two heating tariff systems have been performed in order to outline and highlight the differences between them and to answer the main questions of the study. The results include the status report of the situation concerning the district heating tariff systems in Sweden and Ukraine, comparative analysis of the two systems and suggestion on improvements of the district heating tariff system in the city of Donetsk. The outcomes and suggested improvements do not provide the full picture and all the aspects of the situation, due to the fact that more extensive studies, involving larger resources, would have to be conducted in the area. However, the report provides a good starting point for further studies within the field of district heating tariffs in Ukraine and Sweden
THE SOLUTION OF THE APPROXIMATION PROBLEM OF NONLINEAR DEPENDANCES USING ARTIFICIAL NEURAL NETWORKS
No full textThe paper discusses issues connected with the use of an artificial neural network (ANN) to approximate the experimental data. One of the problems in the development of the ANN is the choice of an appropriate activation function for neurons of the hidden layer and adjusting the parameters of the function in the learning process of the network. The article discusses a three-layer perceptron with one hidden layer, each neuron of which has the activation function in the form of a Gaussian curve. The choice of radial basis activation function allows the use of the direct method of determining the weight coefficients – method of least squares in the process of network training. Thus the quality of the approximation depends on the correct choice of the value parameter of the activation function, which in this case is the width of the Gaussian bell curve. In practice, this parameter is determined by conducting numerical experiments. This is a rather time-taking process. In this paper we propose to define the value of this parameter by the training set, representing the coordinates of the test curve points set with the desired properties. These properties are based on the a priori data of the approximated functions (linear, quadratic, logarithmic, exponential relationship). Because the test curve is given in explicit form, the parameter of activation function is determined from the condition of reaching the minimum of the integral from the squared difference between the values of the test functions and the output of the network. This approach guarantees obtaining the approximating curve with good properties, in particular, it is characterized by the absence of so-called "oscillations" – many inflection points in its graph
THE PROCESS OF FORMING THE CIVIL SOCIETY AS A MEANS OF CORRUPTION COUNTERACTION IN THE RUSSIAN FEDERATION
No full textThe article views the issues of involving civil society into the sphere of corruption counteraction, the problems of civil society formation in Russia, suggests basic forms of realization of its right for anticorruption activity by the civil society
SOLUTION METHOD OF DYNAMIC ROUTING AND WAVE LENGTH ASSIGNMENT PROBLEM FOR WDM NETWORKS WITH TAKING INTO ACCOUNT FOUR-WAVE MIXING EFFECT
No full textThe problem of dynamic route selection and wavelengths assignment in WDM networks is solved. This problem is important in WDM network management when requests are serviced for short-term connection installation and excess traffic is transferred. The proposed solution method is heuristic and is an improvement of the previously known method by taking into account the influence of four-wave mixing and using the new metric for finding the routes prospective for application. This makes it possible to reduce the probability of blocking calls during the connections at the average of 13% and the value of Q factor at 0.812
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