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Search results for: HIGH TEMPERATURE HEAT PUMPS – PERSPECTIVE HEATING SYSTEMS?
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Storing thermal energy from solar collectors for the needs of a detached house
PublicationThis 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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Cattaneo–Christov heat flow model for copper–water nanofluid heat transfer under Marangoni convection and slip conditions
PublicationThis report is devoted to the study of the flow of MHD nanofluids through a vertical porous plate with a temperature-dependent surface tension using the Cattaneo–Christov heat flow model. The energy equation was formulated using the Cattaneo–Christov heat flux model instead of Fourier’s law of heat conduction. The Tiwari–Das model was used to take into account the concentration of nanoparticles when constructing the momentum equation....
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Utilisation of waste heat from the power plant by use of the ORC aided with bleed steam and extra source of heat
PublicationUtilization of waste heat recovered from the exhaust gases of the power generation unit by means of ORC (organic Rankine cycles) installation is considered. The waste heat is available in the form of a stream of hot water having temperature of 90 stC in the amount of 200 MWt. To increase evaporation temperaturę of ORC working fluid the heat of steam from the extraction points from the low-pressure part of steam turbine is used....
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Application of Stirling Engine Type Alpha Powered by the Recovery Energy on Vessels
PublicationThe Stirling engine is a device, in which thermal energy is transformed into mechanical without a contact between the heat carrier, and the working gas closed in the engine. Mentioned feature makes this type of engine very attractive for the use of the recovery energy, taken from other heat devices. One of the potential applications of Stirling engines is the use of thermal energy generated in the ship's engine room for producing...
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Small Scale Gasification of Biomass and Municipal Wastes for Heat and Electricity Production using HTAG Technology
PublicationCombustion and gasification technology utilizing high-cycle regenerative air/steam preheater has drawn increased attention in many application areas. The process is to be realized at temperature level above ash melting point using highly preheated agent. The use of highly preheated media above 900degC provides additional energy to conversion processes and results in considerable...
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Analiza oddziaływań w kryształach związków zawierających w strukturze pierścień pirydynowy
PublicationMożliwość tworzenia się wiązań wodorowych jest kluczowym parametrem z punktu widzenia inżynierii kryształu, ponieważ wiązania wodorowe mają bezpośredni wpływ na strukturę oraz trwałość sieci krystalicznej. Głównym celem niniejszej rozprawy doktorskiej była analiza porównawcza wiązań wodorowych występujących w układach, zawierających w strukturze pierścień pirydynowy. Badane układy podzielono na: (1) układy ze związkami krzemosiarkowymi...
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Influence of Operation Conditions on Temperature Hazard of Lithium-Iron-Phosphate (LiFePO4) Cells
PublicationThe article presents and discusses the results of research on hazard, especially temperature, for selected lithium-ion-phosphate cells operated in accordance with the manufacturer’s recommendations but used under onerous mining conditions. This applies to the performance of cells in battery sets without the application of any management system (BMS). On the basis of the obtained test results, first of all, the influence of the...
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Simulation of fluid structure interaction in a novel design of high pressure axial piston pump
PublicationA novel type of an axial, piston-driven high pressure hydraulic pump with variable capacity marks a significant improvement in the area of the hydraulic machinery design. Total discharge from hydrostatic forces eliminates a need for a servomechanism, thus simplifying operation, reducing weight and introducing the possibility of the pump displacement control by computer. PWK-type pumps, invented in the Gdansk University of Technology,...
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Simulation of fluid structure interaction in a novel design of high pressure axial piston hydraulic pump
PublicationA novel type of an axial, piston-driven high pressure hydraulic pump with variable capacity marks a significant improvement in the area of the hydraulic machinery design. Total discharge from hydrostatic forces eliminates a need for a servomechanism, thus simplifying operation, reducing weight and introducing the possibility of the pump displacement control by computer. PWK-type pumps, invented in the Gdansk University of Technology,...
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Application of Thermo-chemical Technologies for Conversion of Associated Gas in Diesel-Gas Turbine Installations for Oil and Gas Floating Units
PublicationThe paper considers the issue of thermo-chemical recovery of engine’s waste heat and its further use for steam conversion of the associated gas for oil and gas floating units. The characteristics of the associated gas are presented, and problems of its application in dual-fuel medium-speed internal combustion engines are discussed. Various variants of combined diesel-gas turbine power plant with thermo-chemical heat recovery are...
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Morphology and local chain structure of polyamide 6 modified in the solid state with a semi-aromatic nylon salt
PublicationStructural and conformational differences between the polyamide 6 (PA6) homopolymer and two copolymers of PA6 modified in the solid state with 20 and 30 wt% of the semi-aromatic nylon salt of 1,5-diamino-2-methylpentane (Dytek A) and isophthalic acid (IPA) in the feed were investigated. Room temperature wide-angle X-ray diffraction (WAXD) analysis together with 13C{1H} cross-polarization/magic-angle spinning solid-state (CP/MAS)...
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Crystal growth and properties of a binary intermetallic ZrBi2 compound
PublicationSingle crystals of ZrBi2 were grown by a self-flux method. The material adopts TiAs2 structure type with lattice parameters: a = 10.233(4) Å, b = 15.581(2) Å, c = 3.994(5) Å. Crystals of ZrBi2 were studied by means of magnetic susceptiblity, specific heat and resistivity measurements. The compound reveals a metallic-like behavior (RRR = 30). The Sommerfeld coefficient equals γ = 1.59(16) mJ mol-1 K-2 and Debye temperature ΘD =...
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Superconducting properties and electronic structure of NaBi
PublicationResistivity, dc magnetization, and heat capacity measurements are reported for superconducting NaBi. Tc, the electronic contribution to the specific heat γ, the ΔCp/γTc ratio, and the Debye temperature are found to be 2.15 K, 3.4 mJ mol−1 K−2, 0.78, and 140 K respectively. The calculated electron–phonon coupling constant (λep = 0.62) implies that NaBi is a moderately coupled superconductor. The upper critical field and coherence...
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Resonant and nonresonant excitation of waves in a planar magnetosonic flow
PublicationForced propagation of perturbations in a magnetosonic wave are considered. The driving force may be caused by stimulated Mandelstam–Brillouin scattering of optic waves or by intense magnetosonic exciter. Some heating-cooling function which takes into account radiative cooling and unspecified heating is taken into consideration, as well as nonlinearity of a medium. Both these factors make the excitation particular. The analytical...
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Performance of a plate heat exchanger operated with water-Al2O3 nanofluid
PublicationThis study is focused on experimental investigation of a selected type of brazed plate heat exchanger (PHEx). The main aim of the paper was to experimentally check the ability of nanofluids to enhance the performance of PHEx. A typical water-Al2O3 nanofluid was tested and compared to that of the base fluid, i.e. water. Nanoparticles were tested at the concentration of 0.1% and 1% by weight. Impact of the 1 day and 3 days break...
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Performance of a plate heat exchanger operated with water-Al2O3 nanofluid
PublicationThis study is focused on experimental investigation of a selected type of brazed plate heat exchanger (PHEx). The main aim of the paper was to experimentally check the ability of nanofluids to enhance the performance of PHEx. A typical water-Al2O3 nanofluid was tested and compared to that of the base fluid, i.e. water. Nanoparticles were tested at the concentration of 0.1% and 1% by weight. Impact of the 1 day and 3 days break...
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Performance of a plate heat exchanger operated with water-Al2O3 nanofluid
PublicationThis study is focused on experimental investigation of a selected type of brazed plate heat exchanger (PHEx). The main aim of the paper was to experimentally check the ability of nanofluids to enhance the performance of PHEx. A typical water-Al2O3 nanofluid was tested and compared to that of the base fluid, i.e. water. Nanoparticles were tested at the concentration of 0.1% and 1% by weight. Impact of the 1 day and 3 days break...
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Marine propeller shaft bearings under low-speed conditions: water vs. oil lubrication
PublicationThe bearings used in shipbuilding, hydropower, and water pumps have undergone a metamorphosis in recent decades. Because of environmental regulations, lubrication with grease or mineral oil is prohibited. Thus, the standard solutions include water-lubricated bearings with polymer bushings or sealed systems lubricated with oil. When properly designed, assembled, and operated, bearings can operate reliably for years. However, specific...
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Improving performance of large thrust bearings through modeling and experimentation
PublicationLarge thrust bearings are highly loaded machine elements and their failures cause serious losses. Start ups and stoppages of the bearing under load are specially critical regimes of operation. Load carrying capacity depends on the profile of the oil gap. In transient states this profile is also changing. In the design of large thrust bearings minimizing thermo-elastic deformations is an important goal, which can be accomplished...
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Design of power cable lines partially exposed to direct solar radiation – special aspects
PublicationPower cable lines are usually buried in the ground. However, in some cases, their ending sections are mounted along the supports of overhead lines. This leads to a situation where the cables are exposed to direct solar radiation and, consequentially, overheat. The paper presents the advanced computer modelling of power cables’ heating, considering their insolation as well as the effect of wind. The temperature and current-carrying...
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Experiments and numerical modeling of meat and bone meal pyrolysis in a rotary kiln
PublicationThe paper presents aspects of modelling the pyrolysis of meat and bone meal (MBM) in a rotary kiln. The pyrolysis of MBM produces a solid fraction which can be used as a fuel, a liquid fraction with potential chemical applications and a low heating value gas. The meat and bone meal pyrolysis was carried out at the temperature of 900 oC. Main features of experiments and numerical model of the pyrolysis were described. The model...
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A facile structural manipulation strategy to prepare ultra-strong, super-tough, and thermally stable polylactide/nucleating agent composites
PublicationPolylactide (PLA) is a biodegradable thermoplastic widely used in diferent felds, but it should be adequately modifed considering high-performance applications. However, the current processes for developing PLA materials achieve high strength at the expense of toughness or ductility of the materials. Therefore, there is need to develop new strategies for generation of PLA materials with high strength, great toughness, good ductility,...
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Gasification of Densified Biomass (DB) and Municipal Solid Wastes (MSW) Using HTA/SG Technology
PublicationThe necessity of economical and rational use of natural energy sources caused a rapid development of research on the possibilities of using non‐conventional energy resources. Taking the above into account, a new technological process of thermochemical conversion of biomass and communal waste, commonly known as High Temperature Air/Steam Gasification (HTA/SG) and Multi‐Staged Enthalpy Extraction Technology (HTAG‐MEET), was developed....
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Influence of external walls' thermal capacitance on indoor thermal comfort
PublicationThe doctoral thesis presents the results of numerical investigations on the influence of walls’ thermal capacitance on indoor thermal comfort. A proper set of thermal parameters of a building structure can considerably limit the heating / cooling demand, and passively increase the indoor thermal comfort. However the effect of building thermal capacitance on indoor conditions is complex and not always beneficial. Among a great number...
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Implementation of the Boundary Element Method to Two-Dimensional Heat Transfer with Thermal Bridge Effects
PublicationThe work presents an application of the boundary element method applied to a two-dimensional conductive heat transfer. The algorithm of the method is explained and its advantages are outlined. Green's function as a fundamental solution for Poisson's equation in two dimensions was used and the direct approach was applied. The presented results concern building construction elements as typical cases of thermal bridges. Some properties...
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Probing Local Structural Changes by Sharp Luminescent Infrared Nanophosphor for Application in Light-Emitting Diodes
PublicationCr3+-doped infrared phosphors are promising candidates for next-generation phosphor-converted infrared light-emitting diodes (LEDs) because they can, in principle, tune and convert the luminescence spectra from an LED chip. However, most studies focus on broad-band Cr3+-doped phosphors, and the control mechanism of Cr3+-doped phosphors with sharp line emissions remains ambiguous. Here, we report LiGa5(1–x)Al5xO8:Cr3+ phosphors...
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Superconductivity in the Nb-Ru-Ge σ phase
PublicationWe show that the previously unreported ternary σ-phase material Nb20.4Ru5.7Ge3.9 (Nb0.68Ru0.19Ge0.13) is a superconductor with a critical temperature of 2.2 K. Temperature-dependent magnetic susceptibility, resistance, and specific-heat measurements were used to characterize the superconducting transition. The Sommerfeld constant γ for Nb20.4Ru5.7Ge3.9 is 91 mJ mol f.u. −1K−2 (∼3 mJ mol atom−1 K−2) and the specific-heat anomaly at...
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Kinetics of molecular decomposition under irradiation of gold nanoparticles with nanosecond laser pulses—A 5-Bromouracil case study
PublicationABSTRACT Laser illuminated gold nanoparticles (AuNPs) efficiently absorb light and heat up the surrounding medium, leading to versatile applications ranging from plasmonic catalysis to cancer photothermal therapy. Therefore, an in-depth understanding of the thermal, optical, and electron induced reaction pathways is required. Here, the electrophilic DNA nucleobase analog 5-Bromouracil (BrU) has been used as a model compound to...
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Analysing selection of low-temperature medium for cogeneration micro power plant
PublicationThe article analyses the ORC system working with dry and wet low-boiling media which are most frequently used in installations of this type. Two types of cycles were examined, which were the cycle with heat regeneration for dry media: fc72, hfe7100, R227ea, R245fa, R423a and R600a, and the cycle without heat regeneration for wet media: R11, R12, R134a, R718 and 507a. The calculations were performed for the assumed required thermal...
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Analysing selection of low-temperature medium for cogeneration micro power plant
PublicationThe article analyses the ORC system working with dry and wet low-boiling media which are most frequently used in installations of this type. Two types of cycles were examined, which were the cycle with heat regeneration for dry media: fc72, hfe7100, R227ea, R245fa, R423a and R600a, and the cycle without heat regeneration for wet media: R11, R12, R134a, R718 and 507a. The calculations were performed for the assumed required thermal...
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Silicon carbide application issues
PublicationThe main goals of Task 3 and Task 4 of the ordered project ''New technologies based on silicon carbide and their application in HF, high power and high temperature electronics'' are presented
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Curing epoxy resin with anhydride in the presence of halloysite nanotubes: the contradictory effects of filler concentration
PublicationEpoxy resins can be cured with a wide variety of curing agents such as amines and anhydrides, but anhydride curing would be more favorable for research purpose because of epoxy-anhydride curing taking place slowly at room temperature. Incorporation of natural nanosized minerals into epoxy is of environmental importance. Halloysite nanotubes (HNTs) display chemical properties similar to those of silica and alumina, and hydroxyl...
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Energy-Aware High-Performance Computing: Survey of State-of-the-Art Tools, Techniques, and Environments
PublicationThe paper presents state of the art of energy-aware high-performance computing (HPC), in particular identification and classification of approaches by system and device types, optimization metrics, and energy/power control methods. System types include single device, clusters, grids, and clouds while considered device types include CPUs, GPUs, multiprocessor, and hybrid systems. Optimization goals include various combinations of...
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Stirling engines powered by renewable energy sources
PublicationStirling engine is a device that produces mechanical energy using heat from any source of energy, without the need of combustion of any fuel inside the device. Renewable energy sources, which are mostly low-temperature energy sources, can be used to produce mechanical and electrical energy in Stirling engines. The paper presents an overview of the existing prototype Stirling engines designed for using of low-temperature energy...
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Superconductivity in the superhard boride WB4.2
PublicationWe show that the superhard boride WB4.2 is a superconductor with a Tc of 2.05(5) K. Temperature-dependent magnetic susceptibility, electrical resistivity, and specific heat measurements were used to characterize the superconducting transition. The Sommerfeld constant γ for WB4.2 is 2.07(3) mJ mol−1 K−2 and the ΔC/γTc=1.56, which is somewhat higher than what is expected for weakly coupled Bardeen–Cooper–Schrieffer type superconductors....
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Underwater in situ local heat treatment by additional stitches for improving the weldability of steel
PublicationIn this paper the influence of in situ local heat treatment performed by additional stitches on the weldability of high-strength low-alloy (HSLA) S355J2C+N steel was tested. The investigated steel is characterized by high susceptibility to cold cracking. It is necessary to find a method to improve the quality of welded joints. The local heat treatment was applied as an eect of bead-on plate welding made on the face of a Tekken...
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The Boltzmann sequence-structure channel
PublicationWe rigorously study a channel that maps binary sequences to self-avoiding walks in the two-dimensional grid, inspired by a model of protein statistics. This channel, which we also call the Boltzmann sequence-structure channel, is characterized by a Boltzmann/Gibbs distribution with a free parameter corresponding to temperature. In our previous work, we verified experimentally that the channel capacity has a phase transition for...
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INFLUENCE OF NANOPARTICLE CONCENTRATION ON THERMAL PROPERTIES OF THERMAL OIL-MWCNT NANOFLUID
PublicationThis paper deals with measurements of dynamic viscosity, thermal conductivity, electrical conductivity and pH of thermal oil-MWCNT (TO-MWCNT) nanofluid. Nanoparticles were tested at the concentration of 0.001%, 0.005%, 0.01%, 0.05%, and 0,1% by weight. Ultrasonic vibration was used in order to stabilize the dispersion of the nanoparticles. Thermal oil (TO) was selected as a base liquid, because of possible application in ORC systems...
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Analytical Study of Sliding Instability due to Velocity- and Temperature-Dependent Friction
PublicationThe instability of sliding causes deterioration of performance characteristics of tribosystems and is undesired. To predict its occurrence, the motion of a body of a one-degree-of-freedom system with friction is investigated about the steady sliding equilibrium position. The motion equation is formulated with the friction coefficient dependent on the sliding velocity and contact temperature changing due to transient heat conduction...
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Preliminary results from HEDGEHOG REXUS Project - sounding rocket experiment on accelerations, vibrations and heat flow
PublicationAs access to space conditions becomes more available, both technically and economically, scientists' interest in launching finer and more sophisticated experiments grows. This applies now more than ever to fragile by nature biological and chemical experiments. To be qualified for launch, such experiments need to be carefully tested prior to the event. The tests should represent actual launch conditions as closely and in as detailed...
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Multi-nodal PWR reactor model — Methodology proposition for power distribution coefficients calculation
PublicationIn 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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Measured and predicted freeze-thaw days frequencies in climate change conditions in central Poland
PublicationThe rate of progression of geomorphological phenomena is greatly influenced by freeze-thaw processes. In the face of air temperature increasing over the past few decades, a question of the future impact of these processes arises, notably in the temperate and cold climate zones. Using the mean, maximum and minimum daily air temperature data in the period 1951–2018 obtained from three weather stations located in the vicinity of Jeziorsko...
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A Model of Thermal Energy Storage According to the Convention of Bond Graphs (BG) and State Equations (SE)
PublicationThe main advantage of the use of the Bond Graphs method and State Equations for modeling energy systems with a complex structure (marine power plants, hybrid vehicles, etc.) is the ability to model the system components of different physical nature using identical theoretical basis. The paper presents a method of modeling thermal energy storage, which is in line with basic BG theory. Critical comments have been put forward concerning...
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Electronic and ionic relaxations in strontium-borate glass and glass-ceramics containing bismuth and vanadium oxides
PublicationThe topography, microstructure and electrical properties of strontium-borate glass and SBO glass containing bismuth and vanadium oxides, were studied. The structure was measured using X-ray diffraction (XRD), Energy Dispersive X-ray Spectrometer (EDS) and Scanning electron microscope (SEM) methods. The A.C. complex conductivity was investigated as a function of temperature and frequency. The influence of the quantity of bismuth...
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Superconductivity in CaBi2
PublicationSuperconductivity is observed with critical temperature Tc = 2.0 K in self-flux-grown single crystals of CaBi2. This material adopts the ZrSi2 structure type with lattice parameters a = 4.696(1) Å, b = 17.081(2) Å and c = 4.611(1) Å. The crystals of CaBi2 were studied by means of magnetic susceptibility, specific heat and electrical resistivity measurements. The heat capacity jump at Tc is DC/gTc = 1.41, confirming bulk superconductivity;...
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Future of nature, our future. A preregistered report on future time perspective, social value orientation, and pro-environmental outcomes based on data from Poland and Sweden
PublicationIntroduction: The objective of the study was to examine the role of social value orientation and future time perspective to account for individual differences in pro-environmental behaviors, intentions, and opinions about the link between pro-environmental action and pandemic threat (three separate models) in Polish and Swedish samples expected to differ in rate of pro-environmental behaviors (higher in Sweden). We hypothesized...
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Selektywne chłodzenie mózgu noworodka po niedotlenieniu okołoporodowym. Cześć 3. Hybrydowy system selektywnego chłodzenia mózgu noworodka
PublicationZapoczątkowane brakiem tlenu procesy biochemiczne mają zgubne skutki dla układu nerwowego, w szczególności rozwijającego się. Hipotermia, czyli stan oziębienia poniżej pewnych wartości temperatur, spowalnia znacznie lub całkowicie wyhamowuje poszczególne reakcje, i to leży u podstaw jej własności neuroprotekcyjnych. Powyższe twierdzenie poparte licznymi faktami naukowymi leży u podstaw koncepcji selektywnego chłodzenia mózgu i...
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Vertical Temperature Stratification of the Gulf of Gdansk Water
PublicationThe Baltic Sea is characterized by variable hydroacoustic conditions, which depend on hydrological conditions throughout the year. The temperature of the water is the factor that has the greatest impact on the changes in the speed of the sound in this basin. Even at a small depth, we can observe a large temperature gradient affecting the accuracy of the conducted research using hydroacoustic devices. A characteristic feature of...
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Laboratory Determination of Burger's Model Parameters for Visco-elastic Analysis of Road Pavement Materials
PublicationBurger's Model is one of those models that describes performance of asphalt mixtures. Its parameters can be used in road construction analysis based on visco-elastic properties in wide variety of temperatures using dedicated programs (e.g. Veroad) or in Finite Element Method (FEM). Parameters of Burger's Model can be used for example in prediction of low temperature cracking in low winter temperatures or permanent deformation...
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The σ-phase superconductors Nb20.4Rh5.7Ge3.9 and Nb20.4Rh5.7Si3.9
PublicationWe show that the previously unreported ternary σ phases Nb20.4Rh5.7Ge3.9 and Nb20.4Rh5.7Si3.9 are both superconductors with Tc values of approximately 1.9 K. The superconducting transitions were characterized through temperature-dependent magnetic susceptibility, electrical resistance, and specific heat measurements. The Sommerfeld constants, γ, for Nb20.4Rh5.7Ge3.9 and Nb20.4Rh5.7Si3.9 are 89(1) mJ mol-f.u.−1K−2 and 86(1) mJ mol-f.u.−1K−2...