Filtry
wszystkich: 816
wybranych: 744
Wyniki wyszukiwania dla: MV/LV TRANSFORMER, AMI SYSTEM, ENERGY LOSSES
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Hysteresis curves and loops for harmonic and impulse perturbations in some non-equilibrium gases
PublikacjaEvolution of sound in a relaxing gas whose properties vary in the course of wave propagation, is studied. A relaxing medium may reveal normal acoustic properties or be acoustically active. In the first case, losses in acoustic energy lead to an increase in internal energy of a gas similarly as it happens in Newtonian fluids. In the second case, acoustic energy increases in the course of sound propagation, and the internal energy...
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Tailoring a low-energy ball milled MnCo2O4 spinel catalyst to boost oxygen evolution reaction performance
PublikacjaThe development of cost-efficient oxygen evolution reaction (OER) catalysts is one of the most important tasks facing modern techniques for hydrogen production. In this work, for the first time, a low-energy ball milling process of MnCo2O4 (MCO) spinel powders, with a mechanical modification time exceeding 1 day was used. After 6 days of ball-milling, the obtained overpotential of the electrocatalyst reached the value of 375 mV...
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Hysteresis curves for some periodic and aperiodic perturbations in gases
PublikacjaEvolution of sound in a medium whose properties irreversibly vary in the course of wave propagation, is studied. For example, a gas that is a particular case of a Newtonian fluid is considered. Hysteresis curves, pictorial representations of irreversible attenuation of the sound energy, in the plane of thermodynamic states are plotted. The irreversible losses in internal energy are proportional to the total attenuation and depend...
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Economical wood sawing with circular saw blades
PublikacjaMaterial- and energy-saving belong to the basic requirements which are imposed on the contemporary manufacturing processes. Since realization of those processes gives measurable profits not only economical but also ecological. In case of wood sawing with circular saw blades material- and energy-savings are dependent on total overall set of teeth (theoretical kerf) and teeth position accuracy in relation to the workpiece. Hence,...
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Aluminum-TiO2 NPs Composites as Non-precious Catalysts for Efficient Electrochemical Generation of Hydrogen
PublikacjaIn this paper, we demonstrated, for the first time, aluminum titania nanoparticle (Al-TiO2 NP) composites with variable amounts of TiO2 NPs as nonprecious active catalysts for the electrochemical generation of H2. These materials were synthesized by mixing desired amounts of hydrogen titanate nanotubes (TNTs), fabricated here by a cost-effective approach at moderate hydrothermal conditions, with aluminum powder (purity 99.7%; size...
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Porównanie mocy strat energetycznych w pompie wyporowej o zmiennej wydajności określonych bez uwzględnienia bądź z uwzględnieniem mocy ściskania oleju hydraulicznego
PublikacjaPorównano moce strat energetycznych w pompie wyporowej o zmiennej wydajności, określone bez uwzględnienia bądź z uwzględnieniem mocy ściskania oleju hydraulicznego. Ocena mocy ściskania cieczy w pompie stała się możliwa dzięki zastosowaniu, zaproponowanej przez autora, metody określenia stopnia zapowietrzenia cieczy w pompie. W metodzie określenia stopnia zapowietrzenia cieczy w pompie oraz w ocenie mocy strat objętościowych ściskania...
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Design and experimental validation of a single-stage PV string inverter with optimal number of interleaved buck-boost cells.
PublikacjaIncreasing converter power density is a problem of topical interest. This paper discusses an interleaved approach of the efficiency increase in the buck-boost stage of an inverter with unfolding circuit in terms of losses in semiconductors, output voltage ripples and power density. Main trends in the power converter development are reviewed. A losses model was designed and used for the proposed solution to find an optimal number...
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Modification of TiO2 nanotubes by graphene–strontium and cobalt molybdate perovskite for efficient hydrogen evolution reaction in acidic medium
PublikacjaHerein, we demonstrate that modification of TiO2 nanotubes with graphene–strontium and cobalt molybdate perovskite can turn them into active electrocatalysts for hydrogen evolution reaction (HER). For this purpose, a simple method of hydrothermal synthesis of perovskites was developed directly on the TiO2 nanotubes substrate. Moreover, the obtained hybrids were also decorated with graphene oxide (GO) during one-step hydrothermal...
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Solutions of inverter systems in Shore-to-Ship Power supply systems
PublikacjaThe article presents a clearly formulated need for installing S2SP (Shore to Ship Power) systems, in particular Medium Voltage (MV) systems, along with certain solutions of modern inverter systems used in those systems. Requirements and basic configurations of S2SP systems are discussed, focusing in particular on capabilities of the S2SP system with DC distribution busbar. Moreover, on the background of the executing assumptions...
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BADANIE WPŁYWU INDUKCJI REMANENCJI NA STAN PRZEJŚCIOWY JEDNOFAZOWEGO UKŁADU TRANSFORMATOROWEGO
PublikacjaW referacie przedstawiono wyniki badań eksperymentalnych i symulacyjnych wpływu indukcji remanencji w rdzeniu transformatora jednofazowego na jego stan przejściowy przy jego pracy jałowej. Badany obiekt jest układem transformatorowym o dwóch uzwojeniach nawiniętych na zwijanym z blachy anizotropowej rdzeniu w kształcie toroidu. Doświadczenia eksperymentalne polegały na rozładowywaniu kondensatora przez uzwojenie strony pierwotnej...
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Diagnosing marine turbine engines through energy characteristics of their flow section
PublikacjaThe aim of the performed research was to develop of diagnostic method of the flow section of a marine turbine combustion engine based on the level of delamination of its energy characteristics. The here adopted diagnostic model provides for a formulation of the evaluation of the technical conditions based on the measurements of the parameters of the thermodynamic medium in the characteristic control cross-sections of the engine...
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Problems of varistor quality assessment during exploitation
PublikacjaVaristors are commonly used elements which protect power supply networks against high-voltage surges or lightning. Therefore, quality and endurance of these elements is important to avoid losses when an expensive laboratory equipment would not be protected from random overvoltages. Additionally, excessive leakage currents generate serious costs due to high energy consumption. The paper presents shortly properties of varistors that...
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Investigating BiMeVOx compounds as potential photoelectrochemical and electrochemical materials for renewable hydrogen production
PublikacjaIn this study, BiMeVOx compounds (where Me: Co, Mo, Ce, Zr) were synthesized and characterized as potential photoelectrochemical materials for solar water splitting, the hydrogen evolution reaction (HER), and oxygen evolution reaction (OER). The analysis confirmed the successful formation of phase BiMeVOx compounds with the desired crystal structure. Among the tested materials, BiCoVOx(800) showed the highest photocurrent density...
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Comparative study of selected fluids for use in supercritical Organic Ranking Cycles
PublikacjaIn view of increasing interest in improving energy efficiency of energy conversion devices, there is an increasing requirement of combined production of heat and electricity as well as demand for increased implementation of renewable energy resources. The micro cogenerative units utilizing the Organic Rankine Cycle are focusing the attention of many research centres around the world. In the present paper calculations of ORC cycles...
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Badania eksperymentalne transformatora hybrydowego jako kondycjonera napięcia w sieciach typu TN
PublikacjaArtykuł dotyczy układu dystrybucyjnego transformatora hybrydowego (DTH) przeznaczonego do zastosowania w sieciach typu TN. Opisano w nim sposoby podłączenia przewodu neutralnego do układu DTH. W dalszej części artykuł zawiera opis skonstruowanego modelu laboratoryjnego o mocy 16 kVA wraz z zastosowanym algorytmem sterowania. Ponadto przedstawiono wyniki badań eksperymentalnych, ze szczególnym uwzględnieniem oceny dokładności stabilizacji...
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Driving a new perspective Professor Zygmunt Paszota, faculty of ocean engineering and ship technology, Gdansk University of Technology, Poland, explains a new approach to the Sankey Diagram for drive motors
PublikacjaThe paper presents the necessity of replacing the traditional, commonly accepted but erroneous, Sankey diagram of power decrease in the direction of power flow by the diagram, proposed by the Author, of power increase in the direction opposite to the direction of power flow. The proposed view of losses and energy efficiency should be applied to all types of drive motors and drive systems. The presented proposals open a new perspective...
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Innovative Railway Stations
PublikacjaIn relation to modern demographic trends, evolving technologies and environmentfriendly solutions increases the potential of rail considered as sustainable form of public transport. Contemporary tendencies of designing railway stations in Europe are focused on lowering energy consumption and reducing carbon emission. The main goal of the designers is to create a friendly and intuitive space for its users and at the same time a...
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Voltage and Reactive Power Load Flow Optimization in the Power System Using Fuzzy Logic
PublikacjaThe paper presents issues related to voltage control in the power system. An original method of reactive power flow optimization is considered, which leads to improved voltages in the power system and reduced active power losses. The optimization method is based on a procedure that employs fuzzy logic and is supported by a gradient search algorithm. The method has been implemented in PLANS software and verified.
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Wpływ strat mechanicznych w siłowniku teleskopowym zespołu zagęszczającego w pojeździe do usuwania odpadów z pojemników na skuteczność prasowania odpadów
PublikacjaHydraulic telescopic cylinders are used to power the moving wall of rear loader garbage trucks equipped with the traditional "sweep and slide" system. As the garbage compression force is directly dependent on the resistance force of the moving wall, losses in the hydraulic telescopic cylinder influence the compaction process. Taking them into account in the control system may improve the operation of the compaction...
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Frequency Diagnostics of Transformer Insulating Parameters
PublikacjaIn the article is presented experimental analysis and diagnostics of insulating system oil-paper for power transformers, mainly by progressive frequency method – dielectric spectroscopy. In the 1-st part of the article is described base theory about measurement and diagnostics insulating part (oil and paper) of power transformers. In the 2-nd part of article is described measuring method of insulating frequency diagnostics - frequency...
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Determination of the theoretical and actual working volume of a hydraulic motor
PublikacjaA new methodology of determination of the theoretical and actual working volume of a hydraulic motor based on the characteristics of the delivered flow rate into hydraulic motor vs. the rotational speed at a constant pressure drop in the working chambers is described in this paper. A new method of describing the delivered flow rate into a motor per one shaft revolution as a nonlinear function of the pressure drop in the motor working...
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Magnetoacoustic Heating in Nonisentropic Plasma Caused by Different Kinds of Heating-Cooling Function
PublikacjaThe nonlinear phenomena which associate with magnetoacoustic waves in a plasma are analytically studied. A plasma is an open system with external inflow of energy and radiation losses. A plasma’s flow may be isentropically stable or unstable. The nonlinear phenomena occur differently in dependence on stability or instability of a plasma’s flow. The nonlinear instantaneous equation which describes dynamics of nonwave entropy mode...
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Engineering method of tire rolling resistance evaluation
PublikacjaTire rolling resistance is one of the most difficult tire parameters to measure. The reason is that for modern tires the force of rolling resistance corresponds to 0.5–1% of tire load, thus measurements of very small forces must be performed in a heavily loaded system. This constitutes great problems, especially in road conditions. Laboratory measurements are easier to perform, as the environment may be better controlled, but roadwheel...
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Significant Production of Thermal Energy in Partially Ionized Hyperbolic Tangent Material Based on Ternary Hybrid Nanomaterials
PublikacjaNanoparticles are frequently used to enhance the thermal performance of numerous materials. This study has many practical applications for activities that have to minimize losses of energy due to several impacts. This study investigates the inclusion of ternary hybrid nanoparticles in a partially ionized hyperbolic tangent liquid passed over a stretched melting surface. The fluid motion equation is presented by considering the...
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Performance Comparison of a 650 V GaN SSFET and CoolMOS
PublikacjaThe new technology of wide band gap semiconductors is said to outperform up-to-date silicon devices. High voltage Gallium Nitride (GaN) transistors, now emerging in the market, have even three times shorter switching times and even four times smaller energy losses compared to the best in-class Si devices. In this paper the performance of a 650 V GaN SSFET is evaluated and compared with the newest silicon family of CoolMOS™ technology....
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Adaptive dynamic control allocation for dynamic positioning of marine vessel based on backstepping method and sequential quadratic programming
PublikacjaIt is generally assumed in dynamic positioning of over-actuated marine vessels that the control effectiveness matrix (input matrix) is known and constant, or, in case of fault information, it is estimated by the fault detection and diagnosis system. The purpose of the study is to develop the adaptive dynamic positioning control system for an over-actuated marine vessel in the presence of uncertainties and with emphasis on limited...
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Maximum Power Point Technique (MPPT) for PV System Based on Improved Pert and Observe (P&O) Method with PI Controller
PublikacjaPhotovoltaic power generation system has key rule in electricity production. Although, it is clean renewable energy with unlimited resources but it has some drawbacks in efficiency. In order to maximize the efficiency, PV array must drive at maximum power point. For the reason so, several algorithms are used in PV system to track MPP and reduce the...
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Szybkie uziemniki do ograniczania skutków zwarć łukowych w okrętowych rozdzielnicach SN
PublikacjaW artykule scharakteryzowano moc i napięcie łuku, jak również przedstawiono model termodynamiczny służący do obliczania ciśnienia i temperatury gazów w otoczeniu łuku zwarciowego. Przedstawiono przykładowy układ elektrowni okrętowej i zasilania najważniejszych odbiorników na statku do przewozu gazu ziemnego w stanie ciekłym. Na podstawie parametrów prądnic i silników odbiorników zasilanych z rozdzielnicy głównej obliczono prądy...
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Economical wood sawing with circular saw blades of a new design (Ekonomicno piljenje drva kruznom pilom novog dezajna)
PublikacjaMaterial-saving and energy-saving belong to the basic requirements imposed on contemporary manufacturing processes. The realization of these processes gives measurable profi ts, not only economical butalso ecological. In the case of wood sawing with circular saw blades, material- and energy-savings are dependent on total overall set of teeth (theoretical kerf) and teeth position accuracy in relation to the workpiece. Hence, it...
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Cross-border transmission line configuration influence on the electrical power and energy billing process
PublikacjaIn 2015 a connection between the Polish and Lithuanian power systems become fully operational. The connection consists of a 400 kV double circuit transmission line and a back-to-back HVDC substation located on the Lithuanian side. A magnetic couplings between the circuits of the transmission line cause that during power transmission a different values of active power losses are observed in both circuits. This situation may cause...
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Determination of the Theoretical and Actual Working Volume of a Hydraulic Motor—Part II (The Method Based on the Characteristics of Effective Absorbency of the Motor)
Publikacja: In this article, the second method of determination of the theoretical and actual working volume of a hydraulic motor is described. The proposed new method is based on the characteristics of effective absorbency of the motor. The effective absorbency has been defined as the ratio of flow rate in a motor to the rotational speed of the motor’s shaft. It has been shown that the effective absorbency is a nonlinear function of the...
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Lagrangian model of an isolated dc-dc converter with a 3-phase medium frequency transformer accounting magnetic cross saturation
PublikacjaThis article presents a nonlinear equivalent circuit model of an isolated dc-dc converter with a 3-phase medium frequency transformer. The model takes into account the magnetic cross saturation of the 3-phase core-type magnetic circuit. The model is suitable in detailed electromagnetic transient simulations of power systems involving isolated dc-dc converters. The model is developed using the Lagrange energy method. It involves...
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Constant vs. Variable Efficiency of Electric Drive in Train Run Simulations
PublikacjaTrain run simulations, which focus on various power- and energy-oriented aspects, should reflect the losses in the electric powertrain. In general, the powertrain efficiency varies with respect to load and speed. Including this relation in simulation requires knowledge about detailed drivetrain parameters, which are often unavailable. This paper verifies the possibility to approximate the drivetrain efficiency in train run simulations...
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Selected Aspect of IT Tools Application in Process Improvement in Industrial Laundry Services
PublikacjaThe laundry services sector in Poland is growing dynamically and currently has around 13,000 enterprises, mainly micro, small and medium size. The increasing competitiveness of this industry, causes more emphasis on solutions that can in-crease the efficiency of laundry processes and thereby strengthen the market position. One of the methods that can be used for this purpose is Lean Six Sigma, aided by specialized computer software....
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Modelling and analysis of medium frequency transformers for power converters
PublikacjaThe evolutions in power systems and electric vehicles, related to the economic opportunities and the environmental issues, bring the need of high power galvanically isolated DC-DC converter. The medium frequency transformer (MFT) is one of its key components, enabled by the increasing switching frequency of modern power semiconductors like silicon carbide transistors or diodes. The increased operating frequency offers small...
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Problems of Connecting Wind Farms to the Power System with HV Cables
PublikacjaThis paper presents problems caused by connecting wind farms to a power system with high voltage cables. The author highlights possible problems with reactive power compensation, depending on the arrangement of the shunt reactor connection and settings of control systems for reactive power and voltage of the wind farm. The paper also discusses issues of increasing active power losses caused by a shunt reactor installation.
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Modular power converter topologies for energy storage and electric power distribution systems
PublikacjaThis paper describes selected issues concerning realization of energy storage system (ESS) designed to operate in power distribution system. In order to achieve scalability of the system a modular approach is proposed. In addition to this different configuration of the system are analyzed, where depending on requirements and application a scalability in power, in energy capacity of energy storage resource and both in power and...
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Dual Active Bridge (DAB) DC-DC converter for multilevel propulsion converters for electrical multiple units (EMU)
PublikacjaSemiconductor power devices made from silicon carbide (SiC) reached a level of technology enabling their widespread use in power converters. Two different approaches to implementation of modern traction converters in electric multiple units (EMU) have been presented in recent years: (i) 3.3-kV SiC MOSFET-based three-level PWM inverter with regenerative braking and (ii) 6.5-kV IGBT-based four-quadrant power electronic traction transformer...
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Metrisable assessment of the course of stream‑systemic processes in vector form in industry 4.0
PublikacjaThe goal of this paper is to present an innovative conception how to use metrisable vector structure of a manufacturing process, based on quantitative relations between the activity of input streams, features of the product, and effect of losses; all of which are excellent practical solution for Industry 4.0, and in turn intelligent factories. This solution can be a usefull way in the process of building sustainable organization....
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Modern technologies in energy demand reducing of public transport — Practical applications
PublikacjaCity of Gdynia (Poland) exploits one of the most modern trolleybus network in Europe, which has been involved in many projects related to the reduction of energy consumption. Some of them are connected with the improving of energy breaking recovery usage. An experimental stationary storage system at Północna substation, which was tested in 2012-2014, is a bright example of a system which is connected with the improving of the...
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Potential Application of Solar Energy Systems for Electrified Urban Transportation Systems
PublikacjaThe paper presents a novel approach toward the use of solar energy systems in public transportation. The concept of energy generation in PV systems for supplying a trolleybus transportation system is proposed for the city of Gdynia (Poland). The suggested way of energy production allows reducing the environmental harm impact of the municipal transportation system. Moreover, the proposed way of green energy use can be a more profitable...
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Rational Use of Primary Energy in Single-Family Residential Houses
PublikacjaThis work presents results of the primary energy use for heating residential single-family house. Analysis includes domestic hot water system (DHW) and heating, ventilation and air condition system (HVAC). During researches the conventional and alternative energy sources (natural gas, biomass, fuel oil, bituminous coal, lignite or electric energy obtained from electric power system – EPS) were used in DHW and HVAC systems. Furthermore...
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Operation of the Hybrid Photovoltaic-Battery System on the Electricity Market—Simulation, Real-Time Tests and Cost Analysis
PublikacjaThis paper presents research on a hybrid photovoltaic-battery energy storage system, declaring its hourly production levels as a member of a balancing group submitting common scheduling unit to the day-ahead market. It also discusses the variability of photovoltaic system generation and energy storage response. The major research questions were whether the operation of a hybrid photovoltaic-battery energy storage system is viable...
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Computer -Aided Local Energy Planning Using ALEP-PL Software
PublikacjaThe issue of energy system planning, including the planning of local energy systems, is critical, since it affects the security of energy supplies in communities, regions, and consequently the security of energy supply within the country. Energy planning is a complex process that requires integration of different goals i.e. improvement of energy efficiency, increase in the share of renewables in the energy balance and CO2} emission...
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Diamond-Based Supercapacitors with Ultrahigh Cyclic Stability Through Dual-Phase MnO2-Graphitic Transformation Induced by High-Dose Mn-Ion Implantation
PublikacjaWhile occasionally being able to charge and dischargemore quickly than batteries, carbon-based electrochemical supercapacitors(SCs) are nevertheless limited by their simplicity of processing, adjustableporosity, and lack of electrocatalytic active sites for a range of redox reactions.Even SCs based on the most stable form of carbon (sp3carbon/diamond)have a poor energy density and inadequate capacitance retention during longcharge/discharge...
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Optimisation of cooperation of hybrid renewable energy sources with hydrogen energy storage toward the lowest net present cost
PublikacjaThe paper presents the results of a technical and economic analysis of the power supply for a model industrial facility based on intermittent renewable energy sources in the form of wind turbines and photovoltaic modules, supplemented with hydrogen energy storage. The adopted power supply strategy assumed the maximisation of self-consumption of self-produced electricity. Six variants were considered, including two with an energy...
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Postquarter-Point Case of Ship’s Side-Berthing and Its Influence on Marine Fender Pitch
PublikacjaThis paper presents a critical analysis of some selected codes and practical recommendations used as basic rules in the design procedures of modern marine fender systems. The first part of the discussion pertains to the existing equations used in calculating the eccentricity coefficient in the ship’s kinetic energy equation and the maximum allowable fender pitch (spacing) in a set of fenders installed along a quay wall. A new approach...
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Diamond-Phase (Sp3-C) Rich Boron-Doped Carbon Nanowalls (Sp2-C): A Physico-Chemical And Electrochemical Properties
PublikacjaThe growth of B-CNW with different boron doping levels controlled by the [B]/[C] ratio in plasma, and the influence of boron on the obtained material’s structure, surface morphology, electrical properties and electrochemical parameters, such as -ΔE and k°, were investigated. The fabricated boron-doped carbon nanowalls exhibit activity towards ferricyanide redox couple, reaching the peak separation value of only 85 mV. The flatband...
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SiC-Based Power Electronic Traction Transformer (PETT) for 3 kV DC Rail Traction
PublikacjaThe design of rolling stock plays a key role in the attractiveness of the rail transport. Train design must strictly meet the requirements of rail operators to ensure high quality and cost-eective services. Semiconductor power devices made from silicon carbide (SiC) have reached a level of technology enabling their widespread use in traction power converters. SiC transistors oering energy savings, quieter operation, improved reliability...
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Wpływ właściwości czynników chłodniczych na straty egzergii w pompie ciepła (Influence of Refrigerants Properties for Exergy Losses in Heat Pump)
PublikacjaArtykuł poświęcony jest wpływowi występujących w pompie ciepła strat egzergii na jej efektywność energetyczną, a co za tym idzie koszty funkcjonowania instalacji. Autorzy prezentują tu metodologię obliczeniową, która może być zastosowana w procesach projektowania układów cieplno-przepływowych. Obliczenia zostały wykonane na podstawie typowego układu powietrznej pompy ciepła pracującej w klimacie środkowo-europejskim. Ponadto w...