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Publications from the year 2016
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Odzysk fosforu przyszłością oczyszczalni ścieków. Część I: Fosfor jako surowiec strategiczny
- Bartłomiej Cieślik
- Piotr Konieczka
Fosfor jest jednym zasobów nieodnawialnych naszej planety, a jego złoża powoli się wyczerpują. Ze względu na coraz szybciej rozwijające się rolnictwo i przemysł, zapotrzebowanie na fosfor na świecie rośnie w bardzo szybkim tempie. Fakt, że jego złoża naturalne nie są rozmieszczone na całej ziemi równomiernie może w przyszłości prowadzić do konfliktów na tle socjoekonomicznym. Rozwiązaniem może okazać się wdrażanie w oczyszczalniach ścieków technologii odzysku fosforu, gdyż osady ściekowe należą do grupy odpadów pochodzenia organicznego zawierających największe jego ilości. Powszechne wdrażanie tego typu technologii może w przyszłości prowadzić do stabilizacji cen tego pierwiastka oraz uniezależnienia gospodarki fosforowej świata od głównych jego wydobywców jak Maroka, USA, Chin, Republiki Południowej Afryki czy Jordanu.
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Odzysk materiałów w procesach chemicznych recyklingu modułów fotowoltaicznych I i II generacji
- Ewa Klugmann-Radziemska
- Anna Kuczyńska-Łażewska
Wraz ze wzrostem zainteresowania technologią fotowoltaiczną pojawił się problem zagospodarowania odpadów powstałych podczas produkcji i użytkowania oraz pod koniec życia modułu. Technologie recyklingu tego typu odpadów powinny być zgodne z obecnie obowiązującym prawem oraz dostosowane do technologii produkcji przerabianego modułu. Dlatego też tak ważne są badania nad doskonaleniem i opracowywaniem nowych technologii recyklingu. Zaprezentowano stan wiedzy na temat dotychczas opracowanych technologii recyklingu modułów wykonanych z krystalicznego krzemu oraz modułów cienkowarstwowych. Przedstawiono także wyniki własnych badań nad usuwaniem metalizacji przedniej i tylnej z odpadowych krystalicznych ogniw krzemowych.
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Oferta kształcenia a wymogi współczesnego rynku pracy
- Małgorzata Gawrycka
- Justyna Kujawska
Współcześnie zmianom ulegają struktury gospodarek oraz sposoby gospodarowania poszczególnymi zasobami na rynkach. Wpływ na to mają nowoczesne technologie, procesy globalizacji i integracji. Obserwowane dynamiczne zmiany wymuszają włączenie się w proces unowocześniania różnych uczestników rynku. Jednym z nich są instytucje zajmujące się szeroko rozumianym kształceniem, które przygotowują zasoby pracy do wejścia na rynek pracy. Celem niniejszego opracowania jest wskazanie, w jaki sposób uczelnie mogą uatrakcyjnić ofertę kształcenia w sytuacji postępującego spadku liczby studentów. W artykule wykorzystano wyniki badań własnych, których celem było poznanie opinii studentów na temat nowej oferty kształcenia zmierzającej do szerszego włączenia instytucji zewnętrznych i specjalistów w proces nauczania.
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Okna w Gdańsku od średniowiecza do współczesności
- Katarzyna Darecka
Publikacja dotyczy historii stolarki okiennej w Gdańsku od XIV w. do drugiej połowy XX w. Przedstawia budowę, rodzaje i części składowe okien oraz technikę ich wykonania. Historię gdańskich okien podzielono na rozwiązania średniowieczne wraz z wczesnorenesansowymi, późnorenesansowe z barokowymi, klasycystyczne oraz historyzujące, secesyjne a wrescie okna z okresu międzywojennego i powstałe po II wojnie światowej.
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On Accuracy Modeling of Gas Turbine Cycles by the In-house COM-GAS Code
- Paweł Ziółkowski
- Jacek Topolski
- Tomasz Kowalczyk
- Janusz Badur
In this paper, a comparison of accuracy modeling of gas turbine cycles between the basic (classical) model and the in-house COM-GAS code has been presented. The basic model uses a semi-perfect gas and well known projecting assumption. On the other hand, the computational flow mechanics (CFM) basis on a real gas by using thermodynamic tables. The thermodynamic analysis of thermal cycles, simply gas cycle GT8C and gas turbine cycle with heat regeneration according to Szewalski’s idea, has been carried out. The results of thermodynamic calculations of GT8C achieve by an in-house COM-GAS code and the basic models in comparison to data included in available literature for the thermal cycle have been presented. Finally, efficiency increase of gas turbine cycle with heat regeneration according to Szewalski’s patent has been presented, which is dependent on extraction pressure and extraction mass flow rate. Regeneration according to Szewalski’s idea is enabled by adding to the simple cycle devices two regenerative heat exchangers and auxiliary compressor.
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On adaptive selection of estimation bandwidth for analysis of locally stationary multivariate processes
- Maciej Niedźwiecki
- Marcin Ciołek
- Yoshinobu Kajikawa
When estimating the correlation/spectral structure of a locally stationary process, one should choose the so-called estimation bandwidth, related to the effective width of the local analysis window. The choice should comply with the degree of signal nonstationarity. Too small bandwidth may result in an excessive estimation bias, while too large bandwidth may cause excessive estimation variance. The paper presents a novel method of adaptive bandwidth selection. The proposed approach is based on minimization of the crossvalidatory performance measure for a local vector autoregressive signal model and, unlike the currently available methods, does not require assignment of any user-dependent decision thresholds.
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On analog comparators for CMOS digital pixel applications. A comparative study
- Waldemar Jendernalik
Voltage comparator is the only – apart from the light-to-voltage converter – analog component in the digital CMOS pixel. In this work, the influence of the analog comparator nonidealities on the performance of the digital pixel has been investigated. In particular, two versions of the digital pixel have been designed in 0.35 μm CMOS technology, each using a different type of analog comparator. The properties of both versions have been compared. The first pixel utilizes a differential comparator with the increased size and improved electrical performance. The second structure is based on a very simple non-differential comparator with a reduced size and degraded performance. Theoretical analysis of the comparator nonideality effect on the quality of the image obtained from the digital pixel matrix as well as simulation results are provided.
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On bipartization of cubic graphs by removal of an independent set
- Hanna Furmańczyk
- Marek Kubale
- Stanisław Radziszowski
We study a new problem for cubic graphs: bipartization of a cubic graph Q by deleting sufficiently large independent set.
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On constitutive relations in the resultatnt non-linear theory of shells
- Stanisław Burzyński
- Jacek Chróścielewski
- Karol Daszkiewicz
- Wojciech Pietraszkiewicz
- Agnieszka Sabik
- Bartosz Sobczyk
- Wojciech Witkowski
The authors summarize their current research in the field of constitutive modelling in the framework of non-linear 6-parameter shell theory. In particular the description of isotropic, multilayered composite and functionally graded shells is presented.
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On Design Optimization of Miniaturized Microscrip Dual-Band Rat-Race Coupler with Enhanced Bandwidth
- Adrian Bekasiewicz
- Sławomir Kozieł
- Włodzimierz Zieniutycz
In the paper, a novel topology of a miniaturized wideband dual-band rat-race coupler has been presented. Small size of the circuit has been obtained by meandering transmission lines of the conventional circuit. At the same time, the number of independent geometry parameters has been increased in order to secure sufficient circuit flexibility in the context of its design optimization for dual-band operation. Optimum dimensions of the coupler have been obtained through automated simulationdriven design involving surrogate-based techniques. The operating frequencies of the coupler are 1 GHz and 2 GHz, whereas a –18 dB bandwidth is as wide as 22.5 and 11.3 percent for the lower and upper band, respectively. The miniaturization rate is over 37 percent compared to the conventional structure. The design is validated through full-wave EM analysis at fine discretization.
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On local buckling of cold-formed channel members
- Czesław Szymczak
- Marcin Kujawa
The paper deals with local buckling of the compressed flanges of cold-formed thin-walled channel beams subjected to pure bending or axially compressed columns. Arbitrarily shaped flanges of open cross-sections and the web-flange interactions are taken into account. Buckling deformation of a beam flange is described by displacement related to torsion of the flange about the line of its connection with the web. Total potential energy of the flange is a base for the fundamental differential equation of the critical stress of local buckling. The differential equation is derived by means of the stationary total energy principle. The critical buckling stress corresponding to a number of the buckling half-wave matches to the minimum eigenvalue of equation. Numerical examples dealing with single, double bend and lipped flanges are included. The analytical results are compared with the finite element stability analysis carried out by means of the computer systems ABAQUS and CUFSM. The aim of the paper is to find a closed-form analytical solution of the buckling problem, considering web-flange interaction. The results are compared with the finite element method outcomes. Some conclusions are formulated, too.
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On power stream in motor or drive system
- Zygmunt Paszota
In a motor or in a drive system the quantity of power increases in the direction opposite to the direction of power flow. Energy losses and energy efficiency of a motor or a drive system must be presented as functions of physical quantities independent of losses. Such quantities are speed and load. But the picture of power stream in a motor or in a drive system is presented in the literature in the form of traditional Sankey diagram of power decrease in the direction of power flow. The paper refers to Matthew H. Sankey’s diagram in his paper „The Thermal Efficiency of Steam Engines” of 1898. Presented is also a diagram of power increase in the direction opposite to the direction of power flow. The diagram, replacing the Sankey diagram, opens a new perspective of research into power of energy losses and efficiency of motors and drive systems.
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On Reduced-Cost Design-Oriented Constrained Surrogate Modeling of Antenna Structures
- Sławomir Kozieł
- Adrian Bekasiewicz
Design of contemporary antenna structures heavily relies on full-wave electromagnetic (EM) simulation models. Such models are essential to ensure reliability of evaluating antenna characteristics, yet, they are computationally expensive and therefore unsuitable for handling tasks that require multiple analyses, e.g., parametric optimization. The cost issue can be alleviated by using fast surrogate models. Conventional data-driven models are unsuitable for modeling of antenna characteristics if the number of geometry parameters exceeds a few. Here, a novel approach is proposed. It is based on restricting the region of surrogate model validity to a manifold spanned by a set of reference designs corresponding to antenna optimized for various operating frequencies and dielectric permittivity of the substrate material. By focusing the modeling process in the region containing designs that are close-to-optimum from the point of view of the aforementioned operating/material criteria, considerable savings can be achieved in terms of the number of the training samples necessary to set up a reliable surrogate. In the letter, a rigorous analytical formulation of the technique is provided along with a case study of a ring slot antenna. The results are validated through measurements of fabricated antenna prototypes.
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On ship roll resonance frequency
- Wojciech Wawrzyński
- Przemysław Krata
The paper deals with the problem of modeling of rolling motion under a variety of excitation parameters. Special emphasis is put on the analysis and prediction of the frequency of the resonant mode of rolling, since it is often an essential issue in terms of motion of a ship related to her safety against capsizing or excessive amplitudes of roll. The research is performed for both free rolling and excited rolling and it is based on the one-degree-of-freedom equation. The conducted simulations were carried out paying special attention to the effects related to non-linear characteristics of stiffness represented by the GZ- curve and also the non-linearity of damping. A group of ships were considered in order to research and define the key factors governing rolling characteristics. The novel method for rolling period prediction was elaborated and tested revealing significant discrepancies between the results of the pending GM- based IMO-recommended method and the results of numerical simulations performed for a wide range of ships operational loading conditions. Since the research shows a drawback of the IMO formula for rolling period prediction a new formula is proposed instead.
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On some open questions for Ramsey and Folkman numbers
- Stanisław Radziszowski
- Xu Xiaodong
We discuss some of our favorite open questions about Ramsey numbers and a related problem on edge Folkman numbers. For the classical two-color Ramsey numbers, we first focus on constructive bounds for the difference between consecutive Ramsey numbers. We present the history of progress on the Ramsey number R(5,5) and discuss the conjecture that it is equal to 43.
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On the correlation between magnetoacoustic emission and magnetostriction dependence on the applied magnetic field
- Leszek Piotrowski
- Marek Chmielewski
- Bolesław Augustyniak
The correlation between magnetoacoustic emission signal envelopes and magnetostriction curves is investigated. Two sets of samples are being considered: tempered martensitic steel and plastically deformed ferritic steel. It is shown that even though some general relations may be observed, as was demonstrated in the literature, the correlation is not always present. One may not expect to change both quantities in the same way if a serious modification of microstructure takes place, as for instance in the case of plastically deformed samples for which the dislocation cell structure is formed once a certain level (1.5–2%) of deformation is reached. Being so, any relation not taking into account statistical properties of domain structure and pinning sites distribution may not yield a general solution of the problem.
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On the durability of the hydraulic satellite motor working mechanism in overload condition
- Marek Szkodo
- Alicja Stanisławska
- Paweł Śliwiński
The paper presents the newest construction of the hydraulic satellite pump/motor. In this study, the fracture of the hydraulic satellite motor working mechanism is investigated. Factors influencing the durability of satellite working mechanism have been described. The durability of the hydraulic satellite motor working mechanism at a load, corresponding to a pressure of 15 MPa supplied with refined rapeseed oil is very low. Analyses of construction and laboratory tests showed that the satellites teeth wear out the fastest. Results showed that bending fatigue and surface contact fatigue of the satellites are the main cause of the hydraulic satellite motor working mechanism failures
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On the hardness of computing span of subcubic graphs
- Robert Janczewski
- Krzysztof Turowski
In the paper we study the problem of finding ξ-colorings with minimal span, i.e. the difference between the largest and the smallest color used.
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On the Modern and Postmodern Paradigms of Ideology and Social Criticism
- Andrzej Karalus
The article takes on the problem of ideology, critical consciousness and social criticism and distinguishes two ways of thematizing it. The first approach is developed within the post-Hegelian framework. According to this paradigm, critique of ideology is a means of transgressing the antagonistic forms of socialization and emancipating humanity from the false forms of consciousness and corresponding irrational and oppressive social institutions. The postmodern paradigm questions two basic assumptions of the modern approach: firstly, it denies that there exists a possibility to find purely rational and universal contexts, where ideological shackles could be exposed and thrown away; secondly, it rejects the idea that we can rely on the concept of self-awareness or critical reflection as informing our action and elevating our understanding of the social being to the higher level (self-enlightenment model), for critical consciousness has no direct consequences. While portraying the postmodern paradigm, Stanley Fish’s views, considered exemplary to the postmodern rendition of the problem of ideology, will be discussed in a more detailed manner. In the final section of the article a provisional attempt is being made to elucidate what is the task of social criticism within the postmodern paradigm.