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Number of results: 18
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Abstract

Recently a new technology of piezoelectric transducers based on PZT thick film has been developed as a response to a call for devices working at higher frequencies suitable for production in large numbers at low cost. Eight PZT thick film based focused transducers with resonant frequency close to 40 MHz were fabricated and experimentally investigated. The PZT thick films were deposited on acoustically engineered ceramic substrates by pad printing. Considering high frequency and non-linear propagation it has been decided to evaluate the axial pressure field emitted (and reflected by thick metal plate) by each of concave transducer differing in radius of curvature - 11 mm, 12 mm, 15 mm, 16 mm. All transducers were activated using AVTEC AVG-3A-PS transmitter and Ritec diplexer connected directly to Agilent 54641D oscilloscope. As anticipated, in all cases the focal distance was up to 10% closer to the transducer face than the one related to the curvature radius. Axial pressure distributions were also compared to the calculated ones (with the experimentally determined boundary conditions) using the angular spectrum method including nonlinear propagation in water. The computed results are in a very good agreement with the experimental ones. The transducers were excited with Golay coded sequences at 35-40 MHz. Introducing the coded excitation allowed replacing the short-burst transmission at 20 MHz with the same peak amplitude pressure, but with almost double center frequency, resulting in considerably better axial resolution. The thick films exhibited at least 30% bandwidth broadening comparing to the standard PZ 27 transducer, resulting in an increase in matching filtering output by a factor of 1.4-1.5 and finally resulting in a SNR gain of the same order.
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Abstract

The main objective of this study is to improve the ultrasound image by employing a new algorithm based on transducer array element beam pattern correction implemented in the synthetic transmit aperture (STA) method combined with emission of mutually orthogonal complementary Golay sequences. Orthogonal Golay sequences can be transmitted and received by different transducer elements simultaneously, thereby decreasing the time of image reconstruction, which plays an important role in medical diagnostic imaging. The paper presents the preliminary results of computer simulation of the synthetic aperture method combined with the orthogonal Golay sequences in a linear transducer array. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve the signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution. In the work, the 128-element linear transducer array with a 0.3 mm pitch excited by 8-bits Golay coded sequences as well as one cycle at nominal frequencies of 4 MHz were used. The comparison of 2D ultrasound images of the phantoms is presented to demonstrate the benefits of a coded transmission. The image reconstruction was performed using the synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.
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Abstract

The article presents basic changes introduced in the first edition of the governmental Urban Planning and Building Code. The changes regard spatial development, especially planning and permit documents, and competences of the governmental bodies in accepting, legislating and issuing such documents. In this respect, the article points out important regulations for the mining industry, in particular for deposit protection and the initiation of mining projects. In certain cases, critical opinions of some of the governmental institutions are mentioned. In a new document regarding the “Spatial Development Study of a Community”, the draft of the Code orders a division of the community into functional zones. Therefore a mining and extractive industry could be delimited as a functional zone. The Code also specifies that while delimiting a new urbanization area, the documented mining deposits areas should be avoided. In relation to the local spatial plan, the Code establishes the following: in documented strategic mining deposit zones the initiation of non-public purpose investments can only be carried out according to the urban spatial plan. This project also orders that only the local spatial plan can allow for the localization of “establishments that carry a risk of serious industrial breakdown” and “investments that can seriously impact the environment”. The Code also introduces another innovation: the possibility of issuing the local spatial plan with an integrated evaluation on the environmental impact. The “investment permits” are intended to replace both the previous building permits and previous decisions on the conditions of development of the areas not covered in the local spatial plans. The investment permits referring to mining establishments will be issued by the mining administration authorities. The main adverse change for mining is that the exploration of mining deposits owned by the State Treasury loses its previous status of public purposes. The article also indicates that some of the described regulations might be changed during the further legislation process.
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Abstract

The paper presents the theoretical and experimental study of synthetic transmit aperture (STA) method combined with Golay coded transmission for medical ultrasound imaging applications. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution. In the work the 128-element linear transducer array with 0.3 mm pitch excited by the 8 and 16-bits Golay coded sequences as well as a one cycle at nominal frequencies 4 MHz were used. The comparison of 2D ultrasound images of the tissue mimicking phantoms is presented to demonstrate the benefits of coded transmission. The image reconstruction was performed using synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.
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Abstract

The paper refers to previous publications of the author, focused on criteria of casting feeding, including the thermal criterion proposed by Niyama. On the basis of this criterion, present in the post-processing of practically all the simulation codes, danger of casting compactness (in the sense of soundness) in form of a microporosity, caused by the shrinkage phenomena, is predicted. The vast majority of publications in this field concerns shrinkage and feeding phenomena in the cast steel castings – these are the alloys, in which parallel expansion phenomenon does not occur as in the cast irons (graphite crystallization). The paper, basing on the simulation-experimental studies, presents problems of usability of a classic, definition-based approach to the Niyama criterion for the cast iron castings, especially of greater massiveness, for prediction of presence of zones of dispersed porosity, with relation to predictions of the shrinkage type defects. The graphite expansion and its influence on shrinkage compensation during solidification of eutectic is also discussed.
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Abstract

The validation of each simulation code used in foundry domain requires individual approach due to its specificity. This validation can by elaborated on the basis of experimental results or in particular cases by comparison the simulation results from different codes. The article concerns the influence of grey cast iron density curve and different forms of solid fraction curve Fs=f(T) on the formation of shrinkage discontinuities. Solid fraction curves applying Newtonian Thermal Analysis (NTA) were estimated. The experimental and numerical simulation tests were performed on the castings, which were made with Derivative Thermal Analysis (DerTA) standard cups. The numerical tests were realized using NovaFlow&Solid (NF&S), ProCast and Vulcan codes. In this work, the coupled influence of both curves on the dynamics of the shrinkage-expansion phenomena and on shrinkage defects prognosis in grey cast iron castings has been revealed. The final evaluation of the simulation systems usefulness should be based on validation experiment, preceded by comparing the simulation results of available systems which are proposed in given technology.
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Abstract

The presented article contains an analysis resulting from 10 years’ experience in the implementation of the POLVAL Code to mineral assets valuations carried out by Competent Valuators. It had been based on data of more than 100 performed valuations. First and foremost, challenges resulting from preferences given by various relevant regulations to the application of a market-based approach were identified. It was underlined that they prompt Valuators to compromise the quality of the database containing reference transactions. In the case of an income based approach, issues resulting from the adoption of estimates and subjective assumptions were discussed. It was indicated that this fact alone cannot create a valid argument to reject the results of such a valuation providing that they have been implemented in a coherent manner and uncertainty was reflected in the value of the applied discount rate. Separately recommended changes to the present version of the POLVAL Code were presented. In conclusion, a significant, positive role of the introduction of the POLVAL Code for the structuring processes of mineral asset valuation was indicated.
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Abstract

Cells of a multicellular organism are genetically identical but differ in structure and function. This heterogeneity is created by several epigenetic mechanisms during the development of the organism. The epigenetic changes- including DNA methylation, histone post-translational modifications, chromatin remodeling and RNA interference have all been shown to control chromatin structure and regulate a plethora of cellular and organismal processes. There is a strong evidence that epigenetics play a crucial role in the development of diseases such as cancer, schizophrenia or metabolic disorders. The epigenetic regulation underlie memory formation or adaptation to external stimuli. The extent to which environmental effects can provoke epigenetic responses represents an exciting area of future research. Here we review the current knowledge about the epigenetic mechanisms and their relation to the human health and disease.
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Abstract

Local development, based on the use of endogenous potentials, requires the cooperation of muni-cipalities in urban functional areas (agglomerations). However, conducting joint activities in the area of building and running local development policy is a serious challenge. On the one hand, there is a shortage of experience in this area (not counting the short period of functio-ning municipal unions in the years 1920-1939 and intentional inter-communal relations after 1990). In addition, there are still no legal solutions needed (in addition to the act passed in 2017 for the metropolis of Silesia and Zagłębie). In recent years, however, projects of integra-ted territorial investments and other project partnerships have been implemented under the European Union and the Norwegian Financial Mechanism Programs, which result in prac-tical conclusions and legislative recommendations. The most important of them concern the introduction of a new form of partner cooperation and the adoption of a new urban code. Their quick implementation will enable more eff ective cooperation for development.
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Abstract

Simplifications used in simulation program codes require the use of substitute parameters in the material databases (also called apparent or substitutive). On the one hand, they formally fit into the records used in the heat flow model, porosity, properties etc. and on the other hand they should be determined in conditions most similar to the real casting-mould system. The article presents results of a research on thermophysical parameters of gypsum mould used for precision casting moulds. Experiments were carried out on a cylindrical mould made of Plasticast gypsum, in which the heat source was a cylinder filled with liquid aluminium alloy of the temperature of 655°C. Energetic validation was carried out by using the NovaFlow&Solid ver. 6.3 simulation code. As a result of validation tests, substitute thermophysical parameters of gypsum were determined. For determined parameters, best-fit of solidification time from the experiment and simulation was obtained and the curves of gypsum mass heating were satisfactorily recreate.
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Abstract

There is a growing interest in new transportation routes that combine benefits of shorter distances, cost-effective transits and routes not troubled by maritime security concerns. The Northwest Passage offers a package of routes through the Canadian maritime zone; it is 9,000 km shorter than the Panama Canal route and 17,000 km shorter than the Cape Horn route. The Northern Sea Route shortens a Hamburg-Yokohama voyage by 4,800 miles, in comparison with the Suez Canal route. The transpolar route, if it materializes with an ice-free Central Arctic Ocean route, would shorten distances even further. Given the increase in regional and international navigation and shipping in the region, it is therefore not surprising that in recent years Arctic States and international bodies focused on the needs of enhanced safety and environmental standards for polar shipping. In addition to the dedicated domestic polar shipping regulation, primarily in Canada and the Russian Federation, the Arctic Council and International Maritime Organization (IMO) have launched important initiatives. The most important is establishing of international rules for ships operating in polar waters – The Polar Code.
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Abstract

This article reflects on the results the use and eff ectiveness of design coding as urban design / development tool, focusing on the roles of and the relationships between the different actors playing parts in the in the design coding process: the administration, the investors, the designers, the politics and the community. It reveals the gap in professional circles that impacts the development process, which, deepened by the continuous battle between the creative, the market-driven and the regulatory modes praxis. The article is polemical in that it points to the three main parties of this collective process, referring to is as the creative, market and regulatory tyranny. The author proposes that design coding, if used correctly, could be an effective tool regulating the essentials of urbanism, leaving room for creativity and enhanced market value. Design coding as such results in improvement of the quality of both urbans space and housing architecture.
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Abstract

The article contains new approach to creating future of cities and urban regions based on the concept of creative cities. The core of this approach is to treat the genetic code of development as a tool for creating future of the territorial units. The combination and synergy of development genes that were considered as creativity, innovativeness and entrepreneurship allows the use of the fundamental elements of strategic analysis. On one hand, these elements are future challenges of cities and urban regions that they face in the perspective of global trends; on the other hand, they are strategic capabilities of sectors inseparably linked with creativity – sectors of culture, science and business, the integration of which is based on cultural heritage of cities and urban regions. The next issue of the article is the description of the way genes of urban development are manifested in the four sectors. It allows to present the genetic code of development function as a generator of strategic capabilities of creative sectors in cities and urban regions. Finally, the ideas of cross-sectoral undertakings for Polish big cities and urban agglomerations that enable facing intellectual and strategic global challenges were presented. This takes place through the use of strategic capabilities based on the genes of creativity, innovativeness and entrepreneurship; in this way, the genetic code of the development of large cities and urban agglomerations served as the new prospective approach to creating their future.
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Abstract

A spinal code is the type of rateless code, which has been proved to be capacity- achieving over both a binary symmetric channel (BSC) and an additive white Gaussian noise (AWGN) channel. Rateless spinal codes employ a hash function as a coding kernel to generate infinite pseudo-random symbols. A good hash function can improve the perfor- mance of spinal codes. In this paper, a lightweight hash function based on sponge structure is designed. A permutation function of registers is a nonlinear function. Feedback shift registers are used to improve randomness and reduce bit error rate (BER). At the same time, a pseudo-random number generator adopts a layered and piecewise combination mode, which further encrypts signals via the layered structure, reduces the correlation between input and output values, and generates the piecewise random numbers to compensate the shortcoming of the mixed linear congruence output with fixed length. Simulation results show that the designed spinal code with the lightweight hash function outperforms the original spinal code in aspects of the BER, encoding time and randomness.
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Abstract

The performance of the multi-input multi-output (MIMO) systems can be improved by spatial modulation. By using spatial modulation, the transmitter can select the best transmit antenna based on the channel variations using channel state information (CSI). Also, the modulation helps the transmitter to select the best modulation level such that the system has the best performance in all situations. Hence, in this paper, two issues are considered including spatial modulation and information modulation selection. For the spatial modulation, an optimal solution for obtaining the probability of selecting antenna is calculated and then Huffman coding is used such that the transmitter can select the best transmit antenna to maximize the channel capacity. For the information modulation, a multi quadrature amplitude modulation (MQAM) strategy is used. In this modulation, the modulation size is changed based on the channel state variations; therefore, the best modu- lation index is used for transmitting data in all channel situations. In simulation results, the optimal method is compared with Huffman mapping. In addition, the effect of modulation on channel capacity and a bit error rate (BER) is shown.
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Abstract

The paper presents a novel implementation of a time-to-digital converter (TDC) in field-programmable gate array (FPGA) devices. The design employs FPGA digital signal processing (DSP) blocks and gives more than two-fold improvement in mean resolution in comparison with the common conversion method (carry chain-based time coding line). Two TDCs are presented and tested depending on DSP configuration. The converters were implemented in a Kintex-7 FPGA device manufactured by Xilinx in 28 nm CMOS process. The tests performed show possibilities to obtain mean resolution of 4.2 ps but measurement precision is limited to at most 15 ps mainly due to high conversion nonlinearities. The presented solution saves FPGA programmable logic blocks and has an advantage of a wider operation range when compared with a carry chain-based time coding line.
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Abstract

The ethics of ‘theistic absolute morality’ (TAM), as any other ethical theory, must offer a definition of good, describe the connection between good and duty, and provide an effective guidance to human conduct. In the ethics of TAM we find, in my rendering of its claims, an irremediably unsuccessful definition of good, permanently loose connection between moral value and moral duty, and irreparably limited practical efficacy. It is not surprising that it has to be so, as it is a common condition of all ethical systems. The TAM ethics suffers, however, additionally from a unique conceptual trouble, but that is a story I have told elsewhere.
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Abstract

The article discusses the issues of values and social responsibility of universities. On the one hand, the foundations of functioning of universities, which are created by research and education and the role of universities in formation, are recalled. On the other hand, it was reminded that the heart of universities, their DNA, are academic values, defined primarily in the Magna Charta Universitatum, but also in many other documents, such as the Code of Values of the Jagiellonian University. Hence, universities are increasingly often referred to not only as universities of knowledge, but also as universities of wisdom. Together, they are the basis for the social responsibility of universities. However, they alone are not enough for this social responsibility to materialise. Appropriate behaviour and actions are essential. Because knowledge alone is not everything. Such actions are always necessary, but especially when we find ourselves, as a country, humanity and a planet, in a crisis situation related to the climate disaster, which we are already partially experiencing. After the presentation of the most important current facts related to the climate and environmental crisis, the tasks to be undertaken urgently in this context by universities were presented, from broadly understood education, through convincing politicians to ambitious and quick actions, to intensive work on innovative solutions that can contribute to reducing threats brought by the climate and environmental crisis, pointing out, among others, the initiatives proposed by the newly created network of universities U7.
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