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Number of results: 96
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Abstract

We talk to Dr. Bogdan Jaroszewicz, head of the Białowieża Geobotanical Station of the University of Warsaw, about how planned logging in the Białowieża Forest will damage not only the forest itself but also Poland’s image around the globe.
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Abstract

Drought: the very word instills dread, conjuring up images of dried-up wells, barren earth, and – perhaps worse still – empty taps and long lines to access wells. Is Poland likely to experience significant water shortages?
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Abstract

GPR method is perfectly suited for recognizing of sedimentary facies diversity in shallowly occurring sediments if there is a contrast of electrical properties between and/or within each layer. The article deals with the issue of the correlation between GPR surveys results and sedimentological analyses. As a result of this correlation a conceptual model of depositional systems of studied areas was developed. Studies were performed in two areas located in central Poland, where glacial deposits formed in the Middle Polish (Saalian) Glaciation are present. The study was based on 49 sediment samples and 21 GPR profiles. Analyses of lithofacies as well as granulometric and mineralogical composition of deposits of collected samples were carried out, showing the diversity of glacial deposits in both study sites. During GPR measurements shielded antenna with a frequency of 500 MHz was used which allowed high-resolution mapping of the internal structure of deposits and to identify four characteristic radar facies. Correlation of GPR profiles with point, one-dimensional sedimentological studies allowed the unambiguous interpretation of the GPR image and draw conclusions about the formation environment of individual units. Geophysical and sedimentological data obtained during study provide a new and detailed insight into selected glacial deposits in central Poland.
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Abstract

The method of a phase shift angle measurement using conditional averaging of delayed signal absolute value (CAAV) is presented in this paper. The input sinusoidal signal x(t) is without noise. White noise with normal distribution and band limited to low frequencies has been applied as disturbance of delayed sinusoidal signal z(t). Noise n(t) - N(0, σn) is added to the delayed signal - the noised and delayed signal z(t) is obtained. The phase angle shift is proportional to time location of CAAV's minimum (minimum of the characteristic of conditional averaging of delayed signal's absolute value). The phase angle shift can be determined on the basis of conditional averaging value of elaborated algorithm. The characteristics of conditional average of delayed signal's absolute value in the surrounding of the minimum of this function (the results of practical investigations and theoretical calculation) are presented. The experimental variance of characteristic CAAV in surroundings of the minimum (obtained from practical investigations and calculation) is illustrated in the paper. The algorithms of conditional averaging have been elaborated and practically realized in the LabVIEW environment.
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Abstract

The Bulletin of the Polish Academy of Sciences: Technical Sciences (Bull.Pol. Ac.: Tech.) is published bimonthly by the Division IV Engineering Sciences of the Polish Academy of Sciences, since the beginning of the existence of the PAS in 1952. The journal is peer‐reviewed and is published both in printed and electronic form. It is established for the publication of original high quality papers from multidisciplinary Engineering sciences with the following topics preferred: Artificial and Computational Intelligence, Biomedical Engineering and Biotechnology, Civil Engineering, Control, Informatics and Robotics, Electronics, Telecommunication and Optoelectronics, Mechanical and Aeronautical Engineering, Thermodynamics, Material Science and Nanotechnology, Power Systems and Power Electronics. Journal Metrics: JCR Impact Factor 2018: 1.361, 5 Year Impact Factor: 1.323, SCImago Journal Rank (SJR) 2017: 0.319, Source Normalized Impact per Paper (SNIP) 2017: 1.005, CiteScore 2017: 1.27, The Polish Ministry of Science and Higher Education 2017: 25 points. Abbreviations/Acronym: Journal citation: Bull. Pol. Ac.: Tech., ISO: Bull. Pol. Acad. Sci.-Tech. Sci., JCR Abbrev: B POL ACAD SCI-TECH Acronym in the Editorial System: BPASTS.
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Abstract

The Bulletin of the Polish Academy of Sciences: Technical Sciences (Bull.Pol. Ac.: Tech.) is published bimonthly by the Division IV Engineering Sciences of the Polish Academy of Sciences, since the beginning of the existence of the PAS in 1952. The journal is peer‐reviewed and is published both in printed and electronic form. It is established for the publication of original high quality papers from multidisciplinary Engineering sciences with the following topics preferred: Artificial and Computational Intelligence, Biomedical Engineering and Biotechnology, Civil Engineering, Control, Informatics and Robotics, Electronics, Telecommunication and Optoelectronics, Mechanical and Aeronautical Engineering, Thermodynamics, Material Science and Nanotechnology, Power Systems and Power Electronics. Journal Metrics: JCR Impact Factor 2018: 1.361, 5 Year Impact Factor: 1.323, SCImago Journal Rank (SJR) 2017: 0.319, Source Normalized Impact per Paper (SNIP) 2017: 1.005, CiteScore 2017: 1.27, The Polish Ministry of Science and Higher Education 2017: 25 points. Abbreviations/Acronym: Journal citation: Bull. Pol. Ac.: Tech., ISO: Bull. Pol. Acad. Sci.-Tech. Sci., JCR Abbrev: B POL ACAD SCI-TECH Acronym in the Editorial System: BPASTS.
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Abstract

The paper presents a thermodynamic optimization of 900MW power unit for ultra-supercritical parameters, modified according to AD700 concept. The aim of the study was to verify two optimisation methods, i.e., the finding the minimum of a constrained nonlinear multivariable function (fmincon) and the Nelder-Mead method with their own constrain functions. The analysis was carried out using IPSEpro software combined with MATLAB, where gross power generation efficiency was chosen as the objective function. In comparison with the Nelder-Mead method it was shown that using fmincon function gives reasonable results and a significant reduction of computational time. Unfortunately, with the increased number of decision parameters, the benefit measured by the increase in efficiency is becoming smaller. An important drawback of fmincon method is also a lack of repeatability by using different starting points. The obtained results led to the conclusion, that the Nelder-Mead method is a better tool for optimisation of thermal cycles with a high degree of complexity like the coal-fired power unit.
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Abstract

In the study the comparative analysis of test results of drainage of municipal wastewater sludge was conducted with the use of flocculant Praestol 855BS and the mixture of flocculant Praestol 855BS 50% + orange essential oil 50%, as the reagents supporting this process. It was also attempted to reduce unpleasant smells exuding from the drained sludge. The process of drainage of municipal wastewater sludge was conducted in the laboratory setting centrifuge of MPW-350 type. The variable independent parameters were centrifugation time, centrifugation speed, dosage of flocculant Praestol 855BS as well as dosage of mixture in the proportion of flocculant Praestol 855BS (50%) + orange essential oil (50%). The following parameters were subject to assessment: water content in the sludge, dry mass content in the reflux as well as time of maintenance of the oil’s smell in the sludge. The conducted tests demonstrated that the orange essential oil has an impact on drop in resultant quality parameters of the drainage process of municipal wastewater sludge. Batching of the orange essential oil has an impact on considerable reduction of odours exuding from drained wastewater sludge, and thus on improvement of work conditions connected with operation of centrifugal separators. Bearing in mind both the efficient drainage process of wastewater sludge as well as simultaneous reduction of unpleasant smells exuding from the sludge during this process it is assumed and recommended to simultaneously apply both reagents, that is flocculant Praestol 855BS (50%) and orange essential oil, also in the volume of 50%.
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