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Number of results: 68
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Abstract

In this paper a DC-link voltage balancing strategy for multilevel Cascaded H-Bridge (CHB) converter is proposed. Presented solution bases on optimal choice of active vector durations in Space-Vector Pulse Width Modulation (SV-PWM). It makes it possible to DC-link voltages control and to properly generate the output voltage vector in the case of DC-link voltage unbalance. Results of simulation and experimental researches on proposed control strategy are presented in the paper.
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Abstract

Shape optimization on mufflers within a limited space volume is essential for industry, where the equipment layout is occasionally tight and the available space for a muffler is limited for maintenance and operation purposes. To proficiently enhance the acoustical performance within a constrained space, the selection of an appropriate acoustical mechanism and optimizer becomes crucial. A multi-chamber side muffler hybridized with reverse-flow ducts which can visibly increase the acoustical performance is rarely addressed; therefore, the main purpose of this paper is to numerically analyze and maximize the acoustical performance of this muffler within a limited space. In this paper, the four-pole system matrix for evaluating the acoustic performance - sound transmission loss (STL) - is derived by using a decoupled numerical method. Moreover, a simulated annealing (SA) algorithm, a robust scheme in searching for the global optimum by imitating the softening process of metal, has been used during the optimization process. Before dealing with a broadband noise, the STL's maximization with respect to a one-tone noise is introduced for the reliability check on the SA method. Moreover, the accuracy check of the mathematical models with respect to various acoustical elements is performed. The optimal result in eliminating broadband noise reveals that the multi-chamber muffler with reverse-flow perforated ducts is excellent for noise reduction. Consequently, the approach used for the optimal design of the noise elimination proposed in this study is easy and effective.
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Abstract

This article questions the consensus view of The Invincible (Niezwyciężony) as one of Lem’s classical sci-fi fictions. The author contends that in this novel the familiar conventions (later rejected in His Master’s Voice) coexist with a structural design characteristic of his late novels. An analysis of two pieces of the world of The Invincible, usually disregarded by the critics because of their sketchiness, i.e. the story of the extinct Lyrans and the account of the ancient biosphere of Regis III, reveals that in either case Lem no longer cares for the realist credentials of his fiction and does not put the two planets on the astronomical map (which is no doubt deliberate choice). Moreover, in contrast to his earlier novels, his outline histories of the two biospheres contain hidden (but nonetheless unmistakable) parallels to the prehistory of the biosphere of the Earth (though he was no believer in evolutionary repeatability). As this article tries to demonstrate the two peripheral facets of the world depicted in the novel are clearly related and subordinated to the central story line (concerned with the ‘necrosphere’ and humanity). This structural dependence as well as the way in which key aspects of the world depicted in the novel seem to illustrate the theses articulated in Lem’s essays justifi es the conclusion that The Invincible should be treated as the first novel of his late phase, represented – on account of its form – by His Master’s Voice.
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Abstract

The article concerns issues related to need of the introduction of protection prognostic areas, prospective resources pursuant to the new regulations of integrated development and space management in Poland. The article discuss the issues of actual and crucial documents and it also contains some critic and detailed analysis of the documents such as: the Responsible Development Strategy (SOR), Integrated National Development Strategy (ZSRK), Poland Integrated Development Strategy (SZRP). Author also analyzes whether the level of the implementation with the provisions motioned above is compliant with work in the committees reviewing issues in accordance with the work of the inter-ministerial teams for the updating and monitoring the strategy of development, set up at the Coordination Committee for Development Policy. The article indicates, among others, the increase of the legislative risk for the geological-mining or energy industry, the commodity sector. The risk may affect the crucial matters for the industry (functional areas, ICPs, the basis of their recognition in planning documents – taken into consideration as an element in the integrated management system of development). After all the analysis of the current provision, the article contains the summary with the main conclusions.
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Abstract

Excitation of the entropy mode in the field of intense sound, that is, acoustic heating, is theoretically considered in this work. The dynamic equation for an excess density which specifies the entropy mode, has been obtained by means of the method of projections. It takes the form of the diffusion equation with an acoustic driving force which is quadratically nonlinear in the leading order. The diffusion coefficient is proportional to the thermal conduction, and the acoustic force is proportional to the total attenuation. Theoretical description of instantaneous heating allows to take into account aperiodic and impulsive sounds. Acoustic heating in a half-space and in a planar resonator is discussed. The aim of this study is to evaluate acoustic heating and determine the contribution of thermal conduction and mechanical viscosity in different boundary problems. The conclusions are drawn for the Dirichlet and Neumann boundary conditions. The instantaneous dynamic equation for variations in temperature, which specifies the entropy mode, is solved analytically for some types of acoustic exciters. The results show variation in temperature as a function of time and distance from the boundary for different boundary conditions.
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Abstract

This article examines the ontological and spatial character of the waterfront and its influence on perception and design, with particular focus on the process of reproduction of space (Lefebvre) through the generation of mental maps. The convergence of land and water holds in itself an inherent tension between the accessible and the unattainable: the unconscious can be projected on the unknowable underwater space; the unseen domain beyond the horizon can hold a promise of a better world. Another polarity is that of the familiar and the unknown/exotic, off ering a new perspective, a reevaluation of the familiar through the process of ‘ostranenie’ (Shklovsky),’verfremdung’ (Brecht) or ‘estrangement’. The impact of these polarities reaches beyond the spectacle of urban life, the cinematic experience or the theatrum mundi: it enables the reevaluation of the preconceptions of beauty and utility, as exemplifi ed by Futurist Manifesto (Marinetti). These polarities manifest themselves in the hierarchy and dynamics of a waterfront community: physical impermanence of water dwellings foregrounds the contingent nature of human relationships. The waterfront community inhabits superimposed yet separate networks of land and water. First, mental maps have to be generated for each of these separately, then they have to be reconciled in a coherent whole in a separate process. That mapping of the separate networks necessitates a physical transition, a spatial translation that also has linguistic consequences: a different semantic field is assigned to the vocabulary of the everyday, for the significance of the basic terms like ‘home’ or ‘street’ need a modifi ed definition. All the aforementioned processes and phenomena infl uence the ability to perceive, design and reproduce waterfront areas of cities.
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Abstract

This work aims to comprehensively describe the current state of the concept of green infrastructure. It is thus meant to fill in a gap in Polish literature as no comprehensive works concerning green infrastructure have been published in our country even though we have witnessed several such works in other places in the world. The book is mostly addressed to urban planners, spatial planners and landscape architects and it focuses on issues related to developing strategies or green nalyzingture network designs. It is difficult to establish when (and by whom) the term “green infrastructure” was actually coined. The performed literature search indicates that various authors attribute its beginnings to different publications. There is, however, much more consensus regarding the origins of the idea of green infrastructure. Among the concepts regarded as the bases for the notion of green infrastructure we can discern two principal ones: the concept of ecological networks and the concept of greenways (in the US). In Poland, such concepts included the Ecological System of Protected Areas (in Polish: Ekologiczny System Obszarów Chronionych) and System of Open Spaces (in Polish: System terenów otwartych). There is some disagreement regarding the origins of green infrastructure in cities. Analysis of defi nitions of green infrastructure seen in both scientific publications as well as guides and formal documents leads to a single conclusion – we should accept the diversity of interpretations and approaches. A similar diversity in approaches can also be found when looking at the presented typologies. By analyzing the rationale behind the typologies, we can discern three major criteria used by the authors: land cover, land use and ecological value, which is usually associated with formal protection of specifi c areas. The principles of green infrastructure development can be divided into planning-related (multi-functionality, connectivity, multi-scale approach, multi-object approach, cost-effective approach) and governance-related (strategic approach, integration, social inclusion, transdisciplinarity, stakeholder inclusion). Green infrastructure provides people with a multitude of more or less measurable benefits. For the last several years they have been identified and quantified using a concept of ecosystem services. These services are always provided in certain confi gurations, which means that it is only possible to obtain the benefits if the services generating those benefi ts are not contradictory to each other. For several years now, the European Commission has been conducting research on the scope, possibilities and methods of implementing the concept of green infrastructure in the member states. However, the EU’s offi cial position on this subject was declared only in 2013 via Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions – Green Infrastructure (GI) — Enhancing Europe’s Natural Capital. In both EU member states and the United States, non-governmental organizations are the main advocates of the concept of green infrastructure. They have been recently joined by governmental and self-government agencies. The case studies of already developed strategies and designs of the concept of green infrastructure presented in this book illustrate a great diversity of approaches. It is particularly noticeable in the way of identifying specific components and principles of planning and implementation of green infrastructure networks. These differences come mainly from the varying scale of development, adopted interpretations of the notion of green infrastructure as well as specifi c natural, social and sometimes economic conditions in particular areas. Based on the knowledge and experience gathered from the analysis of those cases, we can point out the following problems that Polish planners need to face in order to develop and implement green infrastructure for Polish rural communes, cities and regions: • good selection of the formula and defi nition of green infrastructure that is appropriate for the scale, specifi c conditions of the area, needs of the inhabitants and ambitions of the authorities; • good identification of areas with potential for green infrastructure development that is appropriate for the scale and problems of a specific area (city, village, region) • identification of the scope and degree of confl ict between ecosystem services provided by individual components of green infrastructure; • development of a spatial concept that includes the problem of the inherent conflict between the expected benefits (especially regulation and maintenance versus cultural) coming from individual components of green infrastructure; • proposal of appropriate instruments for implementing the concept and resolving the problem of its coexistence with other concepts of shaping the ecological structure of cities, rural communes and regions in Poland. Summing up, the concept of green infrastructure can be viewed as the ultimate synthesis of all former ideas dealing with the development of ecological structure of cities, open landscapes and regions. In most European countries, apart from Great Britain, the concept of green infrastructure is currently in its implementation phase. Therefore, its true – not paper – history is about to begin and it will probably look diff erent in every country. It will be aff ected by various traditions of development planning, the already developed concepts, degree of involvement of the authorities and – probably above all – the will of those that expect quantifiable benefits from green infrastructure.
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Abstract

City parks play a very important role in an urbanized landscape. They are forms of specially designed green space which combine elements of horticulture with architecture, history and culture. The article presents historical urban parks and old residential-park complexes included in the boundaries of Poznań and currently existing in the wedge-ring system of the urban green space. The aim of the conducted research was to show their historical and current function as well as their general state of preservation and condition. The results are presented in the form of a Table where the historical significance of those objects is compared with their role today.
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Abstract

What is the limit of improvement the structure obtained directly from the liquid state, with possible heat treatment (supersaturation and aging)? This question was posed by casting engineers who put arbitrary requirements on reducing the DAS (Dendrite Arm Spacing) length to less than a dozen microns. The results of tests related to modification of the surface microstructure of AlSi7Mg alloy casting treated by laser beam and the rapid remelting and solidification of the superficial casting zone, were presented in the paper. The local properties of the surface treated with a laser beam concerns only a thickness ranging from a fraction to a single mm. These local properties should be considered in the aspect of application on surfaces of non-machined castings. Then the excellent surface layer properties can be used. The tests were carried out on the surface of the casting, the surface layer obtained in contact with the metal mould, after the initial machining (several mm), was treated by the laser beam. It turned out that the refinement of the microstructure measured with the DAS value is not available in a different way, i.e. directly by casting. The experimental-simulation validation using the Calcosoft CAFE (Cellular Automaton Finite Element) code was applied.
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Abstract

The avant-garde is synonymous with the concept of New Art, the breakthrough in art which took place in the visual arts during the first decades of the 20th century in Russia and then in the USSR. Its representatives, determined by the changes brought about by new technical inventions, especially in the sphere of urbanization, were convinced, like the Italian futurists, that they would be at the foreground of social change, new perceptions and shaping of culture. They believed in the new society which would rend apart the class structure of previous ages when its place would be taken by dynamism and creativity in the service of utilitarian and egalitarian solutions. They believed in their mission, the Promethean idea of a new better world, when man- kind would be liberated from all subjection. This social mood was developing in the whole of Europe, but was particularly strong in Russian society in the last twenty years before World War I. In fact, one could say it was a prelude to the war. From this sequence of events came the conviction held by represen- tatives of New Art about their prophetic message of freedom. The actual reality, the advance of totalitarianism, was a bitter epilogue for the whole formation, for almost all the great artists of the avant-garde. Nevertheless, though rejected and often dying before their time, their works remained, suffused with enthusiasm for the new gravitation – belief in the greatness of mankind – in the new, universal idea.
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Abstract

The paper presents verification of a peak detection method cooperating with infrared radiation detector module applications. The work has been divided into parts including SPICE simulations and presentation of results obtained with the constructed prototype. The design of the peak detector dedicated to applications with very short pulses requires a different approach than that for standard solutions. It is mainly caused due to the ratio of pulse width and time period. In the described application this ratio is less than 10%. The paper shows testing of an analogue circuit which is capable to be inserted in these applications.
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Abstract

Present paper is a continuation of works on evaluation of red, green, blue (RGB) to hue, saturation, intensity (HSI) colour space transformation in regard to digital image processing application in optical measurements methods. HSI colour space seems to be the most suitable domain for engineering applications due to its immunity to non-uniform lightning. Previous stages referred to the analysis of various RGB to HSI colour space transformations equivalence and programming platform configuration influence on the algorithms execution. The main purpose of this step is to understand the influence of computer processor architecture on the computing time, since analysis of images requires considerable computer resources. The technical development of computer components is very fast and selection of particular processor architecture can be an advantage for fastening the image analysis and then the measurements results. In this paper the colour space transformation algorithms, their complexity and execution time are discussed. The most common algorithms were compared with the authors own one. Computing time was considered as the main criterion taking into account a technical advancement of two computer processor architectures. It was shown that proposed algorithm was characterized by shorter execution time than in reported previously results.
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Abstract

Currently commercialization of electric vehicle (EV) is based to minimize the time of starting and acceleration. To undergo this problem multi-input multi-output fuzzy logic controller (MIMO-FLC) affect on propelled traction system forming MMS process was proposed. This paper introduces a MIMO-FLC applied on speeds of electric vehicle, the electric drive consists of two directing wheels and two rear propulsion wheels equipped with two light weight induction motors. The EV is powered by two motors of 37 kilowatts each one, delivering a 476 Nm total torque. Its high torque (476Nm) is instantly available to ensure responsive acceleration performance in built-up areas. Acceleration and steering are ensured by an electronic differential system which maintains robust control for all cases of vehicle behavior on the road. It also allows controlling independently every driving wheel to turn at different speeds in any curve. Direct torque control based on space vector modulation (DTC-SVM) is proposed to achieve the tow rear driving wheel control. The MIMO-FLC control technique is simulated in MATLAB SIMULINK environment. The simulation results have proved that the MIMO-FLC method decreases the transient oscillations and assure efficiency comportment in all type of road constraints, straight, slope, descent and curved road compared to the single input single output fuzzy controller (SISO-FLC).
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Abstract

The article is an attempt to outline the theoretical and methodological reflection on public history in the context of some conceptual models and concrete examples of case studies. Considering discursive situations, suppositions, suggestions and interpellations on the enlightenment postulate with regard to public history (including the issues: magistra vitae, emancipatory project, affirmative history, emotive revolution, critical discourse in the public space, modus art based research) I deal with the issues: what is actually the content of public history: history or memory? Does the enlightenment postulate with regard to public history turn memory into history? Are we dealing with some project concocted by the intelligentsia and scientific elite? What are the current trends in the implementation of critical discourse in public history?
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Abstract

The two chosen estates, Garnizon and Wiszace Ogrody have evolved during the last decade or so in Gdańsk. Both developed with the idea of balanced functionality and New Urbanism despite very diff erent locations. The aim was to combine apartment buildings with shops, other services, hotels, offi ce buildings and cultural venues. Numerous interesting and inviting public spaces were also high on the agenda. It was intended to create an interesting, multifunctional space, to maximise the use of the space throughout the day, also making it eco friendly by minimising the use of cars. That`s how an interesting, beautifull space impacts the energy. The centrally located Garnizon has been quite successful, whereas the more peripherally placed Wiszące Ogrody has not quite succeeded due to fi nancial restrictions and is mainly a housing estate at the moment. The hope is that it will grow into a similar entity with new development and helped by the new rail link.
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Abstract

Bogusław Wolniewicz, inspired by his formal ontology of situations, has put forward a question on semilattices with a unit (A question about joinsemilattices, Bulletin of the Section of Logic 19/3, 1990). The present paper is entirely devoted to this problem in the formulation given by Wolniewicz. First, the meaning of the question is analyzed and its lattice-theoretical and Boolean algebraic contents are exhibited. Second, set-theoretical and topological counterparts of the question are formulated and commented upon.
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Nauka | 2018 | No 4 | 131–164

Abstract

Krzysztof Maurin was an extremely versatile intellectual and academic teacher. He worked in mathematics (monograph “Methods of Hilbert space”), philosophy (publication “Karl Jaspers – a philosopher of truthfulness”), theology (essay “The Son of Man as the foundation of great religions”) as well as in psychology and he taught in the Faculty of Physics of the Warsaw University: I was taught by Him during a second half of His life since the beginning of the 70s. Now we are seeing and presenting his various activities in the time analysed by him in senses of quantum and cosmic physics, Heidegger's philosophy, Schweitzer's theology and human and humanitarian psychology. Therefore we remind below his lectures on Medieval Universities, Humboldt's reform, the XIX century mathematics and indeterministic interpretation of quantum mechanics. Then, according to a chronological order, we are switching our attention to Krzysztof Maurin himself as a student of university underground courses during the time do Nazists occupation in Poland, then as a silent university employee resisting communist totalitarian ideology and after 1956, as a methodical professor of the University of Warsaw collaborating with Western Europe scientists such as LDrs GDrding, Werner Heisenberg, Rene Thom and Friedrich von Weizsacker as well as admiring especially intellectual achievements of Hermann Weyl and Martin Heidegger. To the end of biographical considerations we can observe successes and obstacles encountered by Krzysztof Maurin while He has tended to conciliate various or opposite ways of philosophical understanding or social behaving by his beloved thinkers.
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