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Search results for: state-of-healt
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Design of highly linear tunable CMOS OTA using a linearizing differentialpair in the output stage.
PublicationW pracy przedstawiono analityczną metodę projektowania wzmacniaczy transkonduktancyjnych CMOS o bardzo dobrej liniowości. Praca zawiera również wyniki symulacji pełnej wersji zaprojektowanego układu otrzymane przy użyciu symulatora SPICE.
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Vessel Energy Requirement Prediction from Acceleration Stage Towing Tests on Scale Models
PublicationOne of the most crucial tasks for naval architects is computing the energy required to meet the ship’s operational needs. When predicting a ship’s energy requirements, a series of hull resistance tests on a scale model vessel is carried out in constant speed stages, while the acceleration stage measurements are ignored. Another important factor in seakeeping analysis is the ship’s hydrodynamic added mass. The second law of dynamics...
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Convex set of quantum states with positive partial transpose analysed by hit and run algorithm
PublicationThe convex set of quantum states of a composite K×K system with positive partial transpose is analysed. A version of the hit and run algorithm is used to generate a sequence of random points covering this set uniformly and an estimation for the convergence speed of the algorithm is derived. For K >3 or K=3 this algorithm works faster than sampling over the entire set of states and verifying whether the partial transpose is positive....
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Multi-mode vibronic interactions in the five lowest electronic states of the fluorobenzene radical cation
PublicationThe multi-mode vibronic interactions between the five lowest electronic states of the fluorobenzene radical cation are investigated theoretically, based on ab initio electronic structure data, and employing the linear vibronic coupling model. Low-energy conical intersections, and strong vibronic couplings are found to prevail within the set of X-A and B-C-D cationic states, while the interactions between these two sets of states...
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Deep CNN based decision support system for detection and assessing the stage of diabetic retinopathy
PublicationThe diabetic retinopathy is a disease caused by long-standing diabetes. Lack of effective treatment can lead to vision impairment and even irreversible blindness. The disease can be diagnosed by examining digital color fundus photographs of retina. In this paper we propose deep learning approach to automated diabetic retinopathy screening. Deep convolutional neural networks (CNN) - the most popular kind of deep learning algorithms...
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20+ years of Polish residential real estate prices – a house price index proxy
PublicationInformation on house prices is often considered crucial when assessing developments in economy. However, in Poland for the long time house prices haven’t been tracked in an organized manner. Recent developments, most notably house price indices developed by Poland’s national bank and by the statistical office do not go back more than 10 years, therefore data series are relatively short compared to those of other macroeconomic data. In...
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Governmental supported space internship programmes in new ESA member states - Polish perspective
PublicationOver last 10 years ve new countries - Czech Republic, Romania, Poland, Hungary and Estonia - have joined the European Space Agency. These countries are currently experiencing a considerable increase of space activities aiming to take part in the European and Global space market. New companies, start-ups and consortiums have been created alongside oces of foreign entities have opened their premises in these countries. All of them...
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The role of stakeholders on rejection of bankruptcy applications in the case of “poverty” of the estate: A Polish case study
PublicationThe aim of this article is to supplement the Law and Economics area of science with regard to the scope of the ex ante effectiveness of bankruptcy law using the example of Poland. Bankruptcy law is effective in the ex ante stage when it eliminates from the market insolvent entrepreneurs who cannot even afford to cover the costs of bankruptcy proceedings. In these cases, the bankruptcy court should dismiss the petition for bankruptcy...
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Analysis of Validation and Simplification of Timber-Frame Structure Design Stage with PU-Foam Insulation
PublicationThe transition from experimental studies to the realm of numerical simulations is often necessary for further studies, but very difficult at the same time. This is especially the case for extended seismic analysis and earthquake-resistant design. This paper describes an approach to moving from the experimental testing of an elementary part of a wood-frame building structure to a numerical model, with the use of a commercial engineering...
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Design-Oriented Two-Stage Surrogate Modeling of Miniaturized Microstrip Circuits with Dimensionality Reduction
PublicationContemporary microwave design heavily relies on full-wave electromagnetic (EM) simulation tools. This is especially the case for miniaturized devices where EM cross-coupling effects cannot be adequately accounted for using equivalent network models. Unfortunately, EM analysis incurs considerable computational expenses, which becomes a bottleneck whenever multiple evaluations are required. Common simulation-based design tasks include...
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Influence of Two-Stage Anodization on Properties of the Oxide Coatings on the Ti–13Nb–13Zr Alloy
PublicationThe increasing demand for titanium and its alloys used for implants results in need of such innovative surface treatment that may jointly increase corrosion resistance and biocompatibility, and demonstrate antibacterial protection at no cytotoxicity. The purpose of this research was to characterize the effect of two-stage anodization, performed for 30 min in phosphoric acid, at the presence of hydrofluoric acid in the second stage....
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Evaluation of Mechanical Properties of Two-Stage Concrete and Conventional Concrete Using Nondestructive Tests
PublicationDifferent types of concrete mixtures are used as building materials. The manufacturing process of two-stage concrete (TSC) differs from that of conventional concrete. This study investigated conventional mechanical properties derive empirical relations for estimation of the mechanical parameters of TSC and conventional concrete mixtures. TSC was used to prepare 216 specimens and conventional concrete was used to prepare 108 specimens...
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Plate heat exchanger with porous structure for potential use in ORC system
PublicationThe experimental analysis of passive heat transfer intensification in the case of plate heat exchanger has been carried out. The passive intensification was obtained by a modification of the heat transfer surface, which was covered by a metallic porous microlayer. The experiment was accomplished in two stages. In the first stage the commercial stainless steel gasketed plate heat exchanger was investigated, while in the second one...
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Plate heat exchanger with porous structure for potential use in ORC system
PublicationThe experimental analysis of passive heat transfer intensification in the case of plate heat exchanger has been carried out. The passive intensification was obtained by a modification of the heat transfer surface, which was covered by a metallic porous microlayer. The experiment was accomplished in two stages. In the first stage the commercial stainless steel gasketed plate heat exchanger was investigated, while in the second one...
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The Possibility to use a Nuclear Power Plant as a Source of Electrical Energy and Heat
PublicationIn this article issues concernig the possibility of nuclear power plant (NPP) operation also as a source of heat, which means combined heat and power production, have been described. CHP work is possible and profitable only in those areas where high thermal power demand occurs, which means near city agglomerations such as Warsaw or the Tri-City. Two levels of thermal power delivered to the heating system have been considered. Preliminary...
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EFFECT OF NANOFLUID CONCENTRATION ON TWO-PHASE THERMOSYPHON HEAT EXCHANGER PERFORMANCE
PublicationAn approach – relaying on application of nanofluid as a working fluid, to improve performance of the two-phase thermosyphon heat exchanger (TPTHEx) has been proposed. The prototype heat exchanger consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. Distilled water and nanofluid water-Al2O3...
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New method of processing heat treatment experiments with numerical simulation support
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Heat transfer and fluid flow visualization using liquid crystal thermography
PublicationW pracy przedstawiono możliwości wykrzystania termografii ciekłokrystalicznej do badań wymiany ciepła oraz wizualizacji pola przepływu w elementach urządzeń przemysłowych.
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Reliability model of two-shaft turbine combustion engine with heat regenerator
PublicationW artykule przedstawiono możliwość zastosowania teorii procesów semimarkowskich do opisu niezawodności turbinowego silnika spalinowego. Opracowano model niezawodnościowy w formie siedmiostanowego procesu semimarkowskiego, umożliwiający określenie prawdopodobieństw przebywania silnika w stanie zdatności oraz wyróżnionych stanach niezdatności.
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Experimental study of heat transfer intensification in surface cooling using microjets
PublicationW pracy przedstawiono badania eksperymentalne intensyfikacji wymiany ciepła podczas chłodzenia powierzchni mikrostrugami. Wyniki badań porównano z własnym modelem teoretycznym zjawiska.
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Effect of surface roughness on thermal-hydraulic characteristics of plate heat exchanger
PublicationIn the paper the experimental analysis of passive heat transfer intensification in the case of modeled plate heat exchanger is conducted. The plate heat exchanger is chosen for the analysis because this kind of heat exchangers could be prospectively applied in the ORC systems, however other areas or application are equally possible. The experimental setup was assembled at the Department of Energy and Industrial Apparatus of Gdansk...
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Process modeling inside cylinder in an internal combustion engine with heat regeneration
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Asymptotic modelling and design of some microlayered functionally graded heat conductors
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A comparative study of different methods for heat transfer enhanced by the use of TVG
PublicationArtykuł dotyczy badań eksperymentalnych i numerycznych intensyfikacji wymiany ciepła w modelowym wymienniku ciepła z turbulizatorami przepływu dla różnej geometrii turbulizatorów. Do badań eksperymentalnych wykorzystano termografię ciekłokrystaliczną a modelowanie fizyczne wykonano za pomocą kodu komputerowego FLUENT.
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Use of waste heat to improve the conditions of the piston engines start up
PublicationZespoły prądotwórcze z tłokowymi silnikami spalinowymi są obecnie powszechne stosowane jako awaryjne źródła energii elektrycznej albo elektrownie uzupełniające niedobory energii czy stabilizujące częstotliwość. Ich czas rozruchu powinien być krótki - poniżej 5 minut w przypadku dużych mocy. Zużycie silnika, zużycie paliwa i emisji spalin są silnie uzależnione od stanu cieplnego przed rozruchem. Przedstawiono pomiary laboratoryjne...
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CAPABILITY OF IDENTIFYING AND PREDICTING THE TECHNICAL CONDITION OF PLATE HEAT EXCHANGERS IN OPERATION
PublicationThe paper presents a test stand for plate heat exchangers, allowing to identify the technical condition and to predict durability of the heat exchangers used aboard the sea-going ships: ”Oceanograf”, ”Władysław Orkan”and a passenger-car ferry, under the condition that they are of the same type and manufactured by the same company. In the first part three different installations with plate heat exchangers in the engine rooms...
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Modeling of Heat Source Based on Parameters of Electron Beam Welding Process
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Microjet technology as a perspective intensification method for high performance heat exchangers
PublicationIn the paper two oryginal designs of compact heat exchangers with intensification effect produced by microjets are presented. The technology of microjets manufacturing is an "inhouse" patented design. The idea of such heat exchanger is shown together with the flow and thermal characteristics of the prototypes. The results of performer measurements are satisfactory and encourage for further research of the original designs.
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Numerical single-phase modeling of turbulent flow and heat transfer of nanofluids
PublicationIn this work, Nusselt number and friction factor are calculated numerically for turbulent pipe flow (6 000< Re < 12 000) with constant heat flux boundary condition using nanofluids. The nanofluid is modelled with the single-phase approach and the simulation results are compared with published experimental data.
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Critical Field and Specific Heat in Electron- and Hole-Doped Graphene Superconductors
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Using adsorption chillers for utilising waste heat from power plants
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The Numerical Comparison of Heat Transfer in a Coated and Fixed Bed of an Adsorption Chiller
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Characterisation of the interfacial heat transfer coefficient in hot stamping of titanium alloys
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Finding Temperature Distribution at Heat Recovery Unit Using Genetic Algorithms
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Molar volumes and heat capacities of electrolytes and iIons in N,N-dimethylformamide
PublicationZmierzono gęstości i molowe pojemności elektrolitów typu 1:1 oraz o soli o wyższych liczbach ładunkowych jonów w roztworach w N,N-dimetyloformamidzie w temperaturze 25 stopni Celsjusza. W oparciu o te pomiary wyznaczono standardowe objętości molowe oraz standardowe wartości izobarycznych ciepeł molowych. Uzyskane wartości podzielono na udziały jonowe wykorzystując tetrafenyloboran tetrafenylofosfoniowy (TPTB) jako elektrolit odniesienia....
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Experimental study of boiling heat transfer in the stagnation point of water microjet
PublicationIn the paper presented is a comparison of computational model with experimental data. Numerical model of liquid film with phase change in the stagnation zone due to impingement of the microjet is more widely presented in authors previous work. The radius on which theevaporation process is taking place can be determined from the energy balance on the element of the plate. That radius has also been confirmed experimentally in the...
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Experimental based determination of SCOP coefficient for ground-water heat pump
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Hybrid evolutionary partitioning algorithm for heat transfer enhancement in VLSI circuits
PublicationW niniejszym artykule przedstawiono metodę pozwalającą na polepszenie transferu ciepła z układu scalonego do otoczenia poprzez zwiększenie liczby połączeń zewnętrznych, co pozwoliło na polepszenie przewodności cieplnej układu scalonego. Dla osiągnięcia tego celu opracowano nowy, hybrydowy, ewolucyjny algorytm podziału (ang. Hybrid Evolutionary Partitioning Algorithm - HEPA). Obliczenia przeprowadzone dla wybranych przykładów testowych...
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Natural convective heat-transfers from an isothermal horizontal hemispherical cavity
PublicationPrzedstawiono rozwiązanie analityczne oraz wyniki badań eksperymentalnych i numerycznych konwekcyjnej wymiany ciepła od poziomej izotermicznej kulistej wklęsłej powierzchni.
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Turbulent flow and heat transfer of a liquid film formed by impinging jet.
PublicationZaproponowano prosty model wymiany ciepła w turbulentnym filmie cieczowym utworzonym przez uderzająca strugę. Rozpatrzono dwa przypadki: przepływ rozwijający się i w pełni rozwinięty filmu cieczowego. W obu przypadkach model wyprowadzono na podstawie zmiany grubości filmu w wyniku działania sił bezwładności i sił tarcia. Wyznaczono profile prędkości w obu zakresach co umożliwia wyznaczenie współczynników wymiany ciepła.
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Power and heat from renewable energy sources on energy market in Poland
PublicationPrzedstawiono aktualne uwarunkowania rynków energii w Polsce w odniesieniu do źródeł odnawialnych. Przedstawiono perspektywy rozwojowe. Omówiono wyniki opłacalności budowy małego bloku skojarzonego opalanego słomą.
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Dynamic current-voltage characteristics of dielectrics with extremely low heat conductivity
PublicationZaprezentowano teoretyczny opis metody dynamicznych charakterystyk prądowo-napięciowych w przypadku znacznego gradientu temperatury w ciałach stałych o przewodności jonowej. Otrzymano rozwiązania równania transportu oraz równania charakterystyk, odnoszące się do ruchu cienkiej warstwy nośników ostałej grubości oraz warstwy rozszerzającej się. Podano także przybliżone wyrażenia opisujące czas przelotu nośników. Wyniki zweryfikowano...
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Experimental study of natural convection heat transfer from horizontal conic
PublicationPrzedstawiono badania eksperymentalne i ich wyniki konwekcji swobodnej w wodzie i powietrzu poziomych stożków o kącie przy podstawie 30, 45 i 60 deg. Wyniki badań wykazują dobrą zgodność z rozwiązaniem teoretycznym i z danymi literaturowymi.
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The use of liquid crystal thermography for heat, fluid flow and biomedical research.
PublicationW ostatniej dekadzie termografia ciekłokrystaliczna (TLC) i cyfrowa analiza kolorowych obrazów była z powodzeniem stosowana w różnych aplikacjach technicznych, przemysłowych i biomedycznych. Cienkie warstwy ciekłokrystaliczne zastosowano dla uzyskania lokalnych pól temperatury, współczynników przekazywania ciepła i określenia rodzaju procesu. Materiał ciekłokrystaliczny można również zastosować do wizualizacji pól temperatury i...
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Modernizaciâ sistemi mikrorajonnogo teplopostačaniâ. Modernization of system of district heat supply.
PublicationOmówiono przykład kompleksowej modernizacji osiedlowego systwmu grzewczego. W jego ramach wprowadzono nowe skojarzone źródło energii elektrycznej i ciepła, wymieniono system rurociagów, zaś budynki dwu osiedli poddano konwencjonalnej termomodernizacji. W budynku jednego z osidli zastosowano układ grzejny oparty na gruntowych pompach ciepła oraz kolektorach słonecznych.
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Influence of heat transformations on microstructure and properties of some wrought aluminium alloys.
PublicationOmówiono wpływ spawania na podatność do korozji naprężeniowej stopów Al-Mg i Al-Zn-Mg stwierdzając, że wzrost zawartości cynku wywołuje wzrost właściwości mechanicznych i spadek odporności na korozję naprężeniową. Wykazano, że obróbka cieplna złożona z retrogresji i powtórnego starzenia w przypadku stopów Al-Zn-Mg nie powoduje szczególnych zmian odporności na korozję naprężeniową, co pozostaje w związku z niewielką zmianą struktur...
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Evolution towards simplicity in bacterial small heat shock protein system
PublicationEvolution can tinker with multi-protein machines and replace them with simpler single-protein systems performing equivalent functions in an equally efficient manner. It is unclear how, on a molecular level, such simplification can arise. With ancestral reconstruction and biochemical analysis, we have traced the evolution of bacterial small heat shock proteins (sHsp), which help to refold proteins from aggregates using either two...
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Optimization of the distance between the vertical plates in the convective air heat exchanger
PublicationThis paper examines the influence of the distance between vertical plates on the intensity of free convective heat transfer along with the optimization of this distance. Experimental tests were carried out for one model channel of such an heat exchanger with widths , 0.085 and 0.18 m. This channel, open at the top and sides, was formed by two isothermal symmetrically heated parallel vertical plates of dimensions m and m. The influence...
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Effect of Tube Bundle Arrangement on the Performance of PCM Heat Storage Units
PublicationThe results of comprehensive study on charging and discharging of latent heat storage systems (LHSS) are presented. The multi tube shell-and-tube unit with a variable layouts of the tube bundles are examined. Two tube arrangements – in-line and staggered are tested. A variable number of tubes and different tube positions in a bundle are investigated. Moreover, two pitch ratios are studied. Three commercially available substances...
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Exploring DAD and ADD Methods for Dealing with Urban Heat Island Effect
PublicationThe Urban Heat Island (UHI) effect in the context of climate change and temperature fluctuations is an increasing challenge for contemporary cities. Numerous activities focus on mitigation and adaptation to the UHI effect using both appropriately selected design strategies and technological solutions. However, not all of these technologies support the postulates of ecological and low-carbon cities. Their design, implementation,...