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SFEM Analysis of Beams with Scaled Lengths including Spatially Varying and Cross-Correlated Concrete Properties
PublikacjaThis paper presents the results obtained for plain concrete beams under four-point bending with spatially varying material properties. Beams of increasing length but constant depth were analyzed using the stochastic finite element method. Spatial fluctuation of a uniaxial tensile strength, fracture energy and elastic modulus was defined within cross-correlated random fields. The symmetrical Gauss probability distribution function...
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Mechanical and structural behavior of high-strength low-alloy steel pad welded by underwater wet welding conditions
PublikacjaThe aim of the paper was to determine the metallurgical and mechanical behaviors of a high-strength low-alloy (HSLA) steel pad-welded specimen used in the structures of industrial and naval parts. Then to predict the metallurgical consequences (nature of the phases present) and the mechanical properties (hardness and impact strength) of the pad-welded steel obtained by underwater wet welding with different heat input values. The...
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Effects of Noncontact Shoulder Tool Velocities on Friction Stir Joining of Polyamide 6 (PA6)
PublikacjaIn this study, the effects of the traverse and rotational velocities of the noncontact shoulder tool on the heat generation and heated flux during the friction stir joining of high-density polyamide 6 (PA6) polymer were investigated. The computational fluid dynamics (CFD) method was employed to simulate the thermomechanical phenomena during the friction stir joining (FSJ) process of PA6. A developed model was used to consider the...
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Dilatometry results of SrxTi0.30Fe0.70O3-d materials
Dane BadawczeThis dataset contains results of dilatometry measurements of SrxTi0.30Fe0.70O3-d (x=0.90, 0.95, 1.00 and 1.05) materials. The investigation of the linear thermal expansion was carried out using a Netzsch DIL402 dilatometer. The SrxTi0.30Fe0.70O3-d powder was formed into cylinders and heat up to 1100 °C with a heating rate of 5 °C min−1, dwelled for...
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The experimental results of sorption cycles
Dane BadawczeExperimental studies of sorption cycles were carried out using a prototype research stand, which is a laboratory-scale model of an adsorption chiller. The Intensified Heat Transfer Adsorption Bed (IHTAB) reactor is adapted to the analysis and optimization of various parameters of adsorption systems, e.g., constructions and compositions of adsorption...
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The influence of solution annealing temperature on the properties of Lean Duplex 2101 welded joints in tubes
PublikacjaThe article presents a technology of TIG longitudinal welding without filler material (142) of heat exchanger tubes made of Lean Duplex 2101. The results of studies on the effect of heat treatment (solution annealing) on tensile strength, plasticity, delta ferrite and the structure of smooth tubes are shown. It was found, that the change in solution annealing temperature across the tested range has an impact on mechanical properties...
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The influence of crude glycerol and castor oil-based polyol on the structure and performance of rigid polyurethane-polyisocyanurate foams
PublikacjaIn this work, biopolyol obtained from two types of industrial crops’ processing products: crude glycerol and castor oil was used for preparation or rigid polyurethane-polyisocyanurate foams. Bio-based polyol was obtained via crude glycerol polymerization and further condensation of resulting polyglycerol with castor oil. Rigid polyurethane-polyisocyanurate foams were prepared at partial substitution (0–70 wt.%) of petrochemical...
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A facile strategy for reclaiming discarded graphite and harnessing the rate capabilities of graphite anodes
PublikacjaGraphite negative electrodes are unbeaten hitherto in lithium-ion batteries (LiBs) due to their unique chemical and physical properties. Thus, the increasing scarcity of graphite resources makes smart recycling or repurposing of discarded graphite particularly imperative. However, the current recycling techniques still need to be improved upon with urgency. Herein a facile and efficient hydrometallurgical process is reported to...
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Effects of FSW Tool Plunge Depth on Properties of an Al-Mg-Si Alloy T-Joint: Thermomechanical Modeling and Experimental Evaluation
PublikacjaOne of the main challenging issues in friction stir welding (FSW) of stiffened structures is maximizing skin and flange mixing. Among the various parameters in FSW that can affect the quality of mixing between skin and flange is tool plunge depth (TPD). In this research, the effects of TPD during FSW of an Al-Mg-Si alloy T-joint are investigated. The computational fluid dynamics (CFD) method can help understand TPD effects on FSW...
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Microstructure and Electrical Properties of Fe,Cu Substituted (Co,Mn)3O4 Thin Films
PublikacjaIn this work, thin films (~1000 nm) of a pure MnCo2O4 spinel together with its partially substituted derivatives (MnCo1.6Cu0.2Fe0.2O4, MnCo1.6Cu0.4O4, MnCo1.6Fe0.4O4) were prepared by spray pyrolysis and were evaluated for electrical conductivity. Doping by Cu increases the electrical conductivity, whereas doping by Fe decreases the conductivity. For Cu containing samples, rapid grain growth occurs and these samples develop cracks...
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Nanoparticle-free tissue-mimicking phantoms with intrinsic scattering
PublikacjaWe present an alternative to the conventional approach, phantoms without scattering nanoparticles, where scattering is achieved by the material itself: spherical cavities trapped in a silicone matrix. We describe the properties and fabrication of novel optical phantoms based on a silicone elastomer polydimethylsiloxane (PDMS) and glycerol mixture. Optical properties (absorption coefficient µa, reduced scattering coefficient µs',...
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Multistage generalized adaptive notch filter with improved accuracy
PublikacjaGeneralized adaptive notch filters (GANFs) are estimators of coefficients of quasi-periodically time-varying systems. Current state of the art GANFs can deliver highly accurate estimates of system variations’ frequency, but underperform in terms of accuracy of the coefficient estimates. The paper proposes a novel multistage GANF with accuracy improved in this aspect. The processing pipeline consists of three stages. The preliminary...
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Manoeuvring forces on azimuthing podded propulsor model
PublikacjaThis paper presents the preliminary part of comprehensive manoeuvring open- water tests of a gas carrier model. The paper focuses on open water experiments with an azimuthing podded propulsor. The test program was carried out in the cavitation tunnel and the large towing tank of Ship Hydromechanics Division, Ship Design and Research Centre, Gdańsk. The pod was tested as a pushing unit with a 161.3 mm diameter propeller. Steering...
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Storing thermal energy from solar collectors for the needs of a detached house
PublikacjaThis work evaluates the possibility of meeting a single familu household's need for hot water and heat year round, using solar collectors as the sole energy sourse. The main flaw of energetic systems based on solar energy is that the energy supply is usually insufficient in winter, when it is most needed. This work is going to show thatm for a house surface of 150 m2 and base dimension of 10x10m, it is possible to supply sufficient...
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Control of a vapour microturbine set in cogeneration applications
PublikacjaSystems with microturbines are implemented for local generation of heat and electricity. This paper presents the analysis of control concepts for a vapour microturbine set with a generator with permanent magnets, intended to work in small heat and power plants. Control system variants differed by the selection of controlled signals and set parameters. Possible ways of control were discussed and compared with experimentally determined...
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Charge Transport in High-Entropy Oxides
PublikacjaThis work presents the results of research on the transport properties of the high-entropy BaZr1/8Hf1/8Sn1/8Ti1/8Y1/8In1/8Sm1/8Yb1/8O3–x perovskite oxide with special focus on proton transport. The presented study is part of broader work in which we focus on multiple different chemical compositions with the cation number varying from 5 up to 12 (in B-sublattice). The presence of proton defects is analyzed with thermogravimetry,...
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Multi-nodal PWR reactor model — Methodology proposition for power distribution coefficients calculation
PublikacjaIn the paper the multi-nodal Pressurized Water Reactor (PWR) model called Mann’s model is presented. This models is used for modelling purposes of the heat transfer from fuel to coolant in reactor core. The authors expand widely used in literature approach by defining additional coefficients for the heat transfer model. These parameters approximate the power generation distribution in the PWR reactor core according to the to the...
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A Theoretical and Experimental Study of Moderate Temperature Alfa Type Stirling Engines
PublikacjaThe Stirling engine is a device that allows conversion of thermal energy into mechanical energy with relatively high efficiency. Existing commercial designs are mainly based on the usage of high temperature heat sources, whose availability from renewable or waste heat sources is significantly lower than that of moderate temperature sources. The paper presents the results of experimental research on a prototype alpha type Stirling...
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A method to synthesise groove cam Geneva mechanisms with increased dwell period
PublikacjaThe present study develops a method to synthesise the groove cam Geneva mechanism with increased dwell period. The main condition of the synthesis is to provide the desired law of motion of the wheel. Additional synthesis conditions are the limitation of the maximum pressure angle and the limitation of the minimum curvature radius of the cam profile. Unlike the conventional Geneva mechanisms, the synthesised groove cam Geneva mechanisms...
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A Comparison of STI Measured by Direct and Indirect Methods for Interiors Coupled with Sound Reinforcement Systems
PublikacjaThis paper presents a comparison of STI (Speech Transmission Index) coefficient measurement results carried out by direct and indirect methods. First, acoustic parameters important in the context of public address and sound reinforcement systems are recalled. A measurement methodology is presented that employs various test signals to determine impulse responses. The process of evaluating sound system performance, signals enabling...
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DSC measurments of ammonium vanadate nanocrystals
Dane BadawczeThe DataSet contains the thermal behavior of the ammonium vanadate nanostructures obtained by the hydrothermal method with different conditions. Differential scanning calorimetry (DSC) measurement was carried out under an argon atmosphere from 40C to 560C (with a heating rate of 10 C/min) using Netzsch STA 449 F1. The results reveal the differences...
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Assessment of crack resistance of ship steels according to SEP 1390 standard
PublikacjaThe aim of the study was to evaluate the weldability of E36 nd NVE-36 steels by bending test according to SEP 1390. In the case of the specimen from E36 steel 9 external cracks were found, 5 of which were stopped in the fusion line and 4 in heat affected zone. In the case of the specimen from NVE-36 steel 8 external cracks were found, 4 of which were stopped in the fusion line and 4 in heat affected zone. Results of bending test...
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Power enhancement of the Brayton cycle by steam utilization
PublikacjaThe paper presents thermodynamic analysis of the gas-steam unit of the 65 MWe combined heat and power station. Numerical analyses of the station was performed for the nominal operation conditions determining the Brayton and combined cycle. Furthermore, steam utilization for the gas turbine propulsion in the Cheng cycle was analysed. In the considered modernization, steam generated in the heat recovery steam generator unit is directed...
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Współczynniki strat energetycznych w elementach napędu hydrostatycznego
PublikacjaW każdym układzie napędowym należy zastąpić obraz przepływu mocy opisany dotychczas powszechnie stosowanym wykresem Sankey’a spadku mocy zgodnego z kierunkiem przepływu mocy proponowanym przez autora wykresem wzrostu mocy w układzie przeciwnego do kierunku przepływu mocy. Należy więc opisywać straty i sprawność energetyczną a także pole pracy każdego silnika i układu napędowego jako zależne od wielkości fizycznych niezależnych...
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Właściwości stali S460M napawanej pod wodą metodą lokalnej komory suchej
PublikacjaW artykule przedstawiono wyniki badań próbek ze stali S460M wykonanych pod wodą metodą lokalnej komory suchej. Pomiary twardości oraz analiza strukturalna wykazały, że dla określonych ilości wprowadzonego ciepła możliwe jest wykonanie złączy bez niezgodności spawalniczych. Stwierdzono formowanie się w pewnych warunkach pęknięć zimnych w SWC wywołanych procesami odprowadzania ciepła z materiału, które są charakterystyczne dla spawania...
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EFFECT OF PRESS DRYING ON DIMENSION STABILITY AND DENSITY OF BEECH WOOD,
PublikacjaTimber is traditionally dried in kilns by processes that often take several days or weeks to complete. At present, it is possible to apply several methods of rapid drying of timber, including, for example, press drying. This research is based on the use of this process. Drying was performed using the heating plates with a temperature of 160 °C. Three pressures were compared in the research 1.0 MPa, 1.4 MPa, and 1.8 MPa. The density...
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Thermal Energy Storage with PCMs in Shell-and-Tube Units: A Review
PublikacjaThe paper presents a survey of the experimental and numerical studies of shell-and-tube systems in which phase change material (PCM) is used. Due to the multitude of design solutions for shell-and-tube systems, the emphasis is placed on double-tube (DT), triplex-tube (TT), and multitube (MT) units. Additionally, only single-pass systems are considered. Particular attention is paid to the method of heat transfer intensification....
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Curved Surface Minijet Impingement Phenomena Analysed with ζ-f Turbulence Model
PublikacjaThe jet impingement phenomenon plays an important role among the heat transfer intensification methods. Very often its application and analyses refer to simple flat surfaces, while there is a lack of information in the literature for cases addressing curved surfaces. In the present work, the single jet impingement on the non-flat (concave and convex) surface is studied for a wide range of geometries, which originate from the mini-jet...
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Thermoelectric and electrical transport properties of mixed-conducting multicomponent oxides based on Ba(Zr,Ce)O3-δ
PublikacjaIn this work, the chosen physicochemical properties of single-phase multicomponent oxides BaTi1/8Fe1/8Co1/8Y1/8Zr1/8Sn1/8Ce1/8Hf1/8O3-δ and BaTi1/9Fe1/9Co1/9Y1/9Zr1/9Sn1/9Ce1/9 Hf1/9Bi1/9O3-δ were studied. The microstructure of the compounds strongly depended on the presence of bismuth in the structure. The electrical transport studies showed a level of electrical conductivity of ∼10−3 - 10−2 S/cm in the temperature range 673–1073...
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Rurka ciepła z pętlą obiegową jako urządzenie do odzysku ciepła
PublikacjaW pracy przedstawiono możliwości odzysku ciepła za pomocą rurki ciepła z pętlą obiegową (ang. loop heat pipe)
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Numerical investigations of the engine cooling system in a small power vesel pod propulsion system
PublikacjaThe development of electronics and electrotechnology enabled to put electric motors of the alternating current in the pod and to use them for the main drive of ships. A lot of heat which must be picked up from the system is a problem which is turning up at applying the system of this type. Many big ships lately contended with these problems. Building the small propeller for the boat powered with solar power we decided to check...
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Role of bead sequence in underwater welding
PublikacjaThis paper presents examinations of the role of the bead sequence in underwater welding. Two specimens of wet welded layers made by covered electrodes with the use of normalized S355G10+N steel were welded by a reasonable bead sequence. For each specimen, metallographic macro- and micro-scopic tests were done. Then, Vickers HV10 hardness measurements were conducted for each pad weld in the welded layer. The results show that welding...
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On Accuracy Modeling of Gas Turbine Cycles by the In-house COM-GAS Code
PublikacjaIn 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...
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APPLICATION POSSIBILITIES OF THE S960 STEEL IN UNDERWATER WELDED STRUCTURES
PublikacjaIn this paper, the application possibilities of the ultra-high strength (UHSS). Domex 960 steel in the underwater welded structures are analyzed. In the research, the investigated material has been tested in bead-on-plate wet welding conditions with the usage of different heat input values, namely 0.63 kJ/mm, 0.72 kJ/mm and 0.93 kJ/mm. Specimens were performed by the manual metal arc (MMA) welding method with the usage of rutile...
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Dobór głównych parametrów instalacji grzewczych spalinowych siłowni okrętowych z wykorzystaniem metod i modeli probabilistycznych
PublikacjaPraca doktorska przedstawia nowatorską metodę projektowania okrętowych instalacji grzewczych. Metoda ta powstała dzięki analizie statystycznej danych zebranych z kilkunastu statków dotyczących między innymi wytwarzania pary w kotłach utylizacyjnych i zapotrzebowania na ciepło przez odbiorniki pary. Zaproponowany w pracy proces projektowy wykorzystuje równania korelacji wynikające z analizy statystycznej. Wytwarzanie ciepła oraz...
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Generalized Dobrushin Coefficients on Banach Spaces
PublikacjaThe asymptotic behavior of iterates of bounded linear operators (not necessarily positive), acting on Banach spaces, is studied. Through the Dobrushin ergodicity coefficient, we generalize some ergodic theorems obtained earlier for classical Markov semigroups acting on L1 (or positive operators on abstract state spaces).
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Structure and thermoelectric properties of Te/Ag/Ge/Sb (TAGS) materials obtained by reduction of melted oxide substrates
PublikacjaThe Ge0.77Ag0.1Sb0.13Te1alloy was fabricated by a novel two step route. For that purpose firstly the oxide reagents were melted at high temperature and quenched into pellets. After that pellets were milled to the powder and then reduced in hydrogen at various temperatures and for various periods of time. Energy dispersive X-ray analysis indicated the possibility of successful fabrication of stoichiometric thermoelectric materials...
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The effect of laser on metal surfaces for multidisciplinary usage in material and thermal engineering
PublikacjaThe subject of heat transfer and cooling systems is still a matter of contention in many different fields of science and industry. Infrigidation is much more difficult than warming, and so, much more needed in more and more different devices, starting from massive industrial machinery and air conditioning in commercial buildings, up to micro and nano-surgery tools. In fact, the size of many cooling systems is still a problem. It...
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Superconductivity in the niobium-rich compound Nb5Se4
PublikacjaThe niobium rich selenide compound Nb5Se4 was synthesized at ambient pressure by high-temperature solid–state reaction in a sealed Ta tube. Resistivity and heat capacity measurements reveal that this compound is superconducting, with a Tc = 1.85K. The electronic contribution to the specific heat γ and the Debye temperature are found to be 18.1 mJmol−1K−2 and 298 K respectively. The calculated electron-phonon coupling constant λep...
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Numerical simulation of hardening of concrete plate
PublikacjaThe paper presents a theoretical formulation of concrete curing in order to predict temperature evolution and strength development. The model of heat flow is based on a well-known Fourier equation. The numerical solution is implemented by means of the Finite Difference Method. In order to verify the model, the in situ temperature measurements at the top plate of a road bridge were carried out. A high agreement between numerical...
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Review on friction stir welding of dissimilar magnesium and aluminum alloys: Scientometric analysis and strategies for achieving high-quality joints
PublikacjaMagnesium and aluminum alloys continually attract interest as lightweight structural materials for transport applications. However, joining these dissimilar alloys is very challenging. The main obstacle that hinders progress in dissimilar Mg-Al joining is the formation of brittle intermetallic compounds (IMCs). As a solid-state joining technique, FSW is an excellent candidate to attenuate the deleterious IMC effects in dissimilar...
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Large magnetoresistance and first-order phase transition in antiferromagnetic single-crystalline EuAg4Sb2
Publikacjapresent the results of a thorough investigation of the physical properties of single crystals using magnetization, heat capacity, and electrical resistivity measurements. High-quality single crystals, which crystallize in a trigonal structure with space group , were grown using a conventional flux method. Temperature-dependent magnetization measurements along different crystallographic orientations confirm two antiferromagnetic...
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Influence of the Tool Rotational Speed on Physical and Chemical Properties of Dissimilar Friction-Stir-Welded AA5083/AA6060 Joints
PublikacjaAluminum alloys have been successfully used in the railroad and automotive industries because of their potential to significantly reduce component weights, and their good mechanical and anti-corrosion properties. Problems with joining aluminum alloys are characterized by low weldability, which influences the need for studies focused on unconventional methods. The environmentally friendly and low-cost friction-stir-welding method...
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Układ kompensacji wpływu wzniesienia oraz przyspieszenia w przyczepie do badania oporu toczenia
PublikacjaW artykule przedstawiono metodę pomiaru współczynnika oporu toczenia przy wykorzystaniu przyczepy opracowanej w Zakładzie Pojazdów na Politechnice Gdańskiej. Następnie omówiono opatentowany układ bezwładnościowy do korekcji wpływu wzniesienia oraz metodę korekcji wpływu przyspieszenia wzdłużnego. W dalszej części przedstawiono przykładowe wyniki obrazujące pomiar współczynnika CRR na wzniesieniu przy zmiennej prędkości.
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Early-Age Hydration Reaction of Cement Mortars with the Participation of Aluminosilicate Microsphere Fractions
PublikacjaThe paper presents the influence of two fractions (M1 and M2) of aluminosilicate microspheres in the amount of 0.0%, 1.5%, 3.5%, and 5% as a cement substitute on the early heat of hydration of cement mortars assessed by isothermal calorimetry (IC). The study results showed a higher accumulated heat of hydration for cement mortars with 1.5% of the test material for both grain fractions. In turn, mortars with 3.5% and 5% of smaller...
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Comparative study of a bottoming SRC and ORC for Joule–Brayton cycle cooling modular HTR exergy losses, fluid-flow machinery main dimensions, and partial loads
PublikacjaEnergy conversion efficiency increase in power plants with high-temperature gas-cooled reactors via implementation of the bottoming cycle was investigated under nominal and minimal thermal load of a high-temperature reactor (HTR). Heat transfer surface area and turbine outlet volumetric flow rate in bottoming cycles was also investigated. Water and two low-boiling point working fluids (ammonia and ethanol) were analyzed. Analyzed...
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Reaction quotients of reforming reactions for SOFC and SOFC with LSCNT layer fueled by biogas mixture at 750 C - longterm
Dane BadawczeThe dataset contains the calculated reaction quotients of reforming reactions for the SOFC and SOFC with LSCNT layer (La0.27Sr0.54Ce0.09Ni0.1Ti0.9O3-s) fueled by synthetic biogas mixture (60:40 CH4:CO2). The outlet concentration of the gases from SOFC were measured using novel FTIR-based unit.
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Brunauer-Emmett-Teller (BET) surface analysis of titanium dioxide (TiO2) and silicon dioxide (SiO2) used for coating of expanded polystyrene spheres (EPS)
Dane BadawczeData refer to the results of BET surface area of TiO2 and SiO2 powders used for coating of expanded polystyrene spheres. The detailed measurement and equipment data was described in readme BET.txt file.TiO2 was treated firstly in autoclave at 150 C degrees for 1h, then was further heat treated in Ar at 400 C degrees. As a raw material TiO2 was used,...
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Electrical measurements of the dewetting of metal thin films
Dane BadawczeIn situ observations of dewetting of thin films is very complicated. One of the method, that helps to observe it, could be electrical measurements. For experiments, thin gold, silver and gold-silver nanoalloy films were deposited by magnetron sputtering method. Films were deposited on a Corning glass substrates. Samples were measured by four point method...
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OBSERVATION OF THE THERMOSIPHON EFFECT IN THE CIRCULATION OF ACETONE AS WORKING FLUID IN MODERN COOLING SYSTEM
Publikacjaplants or computer server rooms has led to the demand for new and reliable methods for electronic cooling. Because of bigger and bigger power levels and miniaturization of the electronic devices, lack of free space in such a high heat flux. The increasing integration of electronic logy that supposed to be designed for high thermal performance, low mass, and able to work in harsh environments. In this paper presented a prototype...