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Wyniki wyszukiwania dla: FRACTURE TOUGHNESS, ORTHOGONAL CUTTING, CUTTING FORCE, CUTTING POWER, FRAME SAWING, PINE WOOD
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The Issues of Reactive Power Compensation in High-voltage Transmission Lines
PublikacjaThis paper discusses the selection of compensation shunt reactors for a double-circuit 400 kV transmission line using the example of the newly built Elk Bis – Alytus transmission line. The analysis takes into account various conditions of the power system. The published results relate to voltage levels in steady states and during switching processes and short circuits.
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Shear fracture of longitudinally reinforced concrete beams under bending using Digital Image Correlation and FE simulations with concrete micro-structure based on X-ray micro-computed tomography images
PublikacjaThe paper presents experimental and numerical investigations of the shear fracture in rectangular concrete beams longitudinally reinforced with steel or basalt bar under quasi-static three point bending. Shear fracture process zone formation and development on the surface of beams was investigated by Digital Image Correlation (DIC) whereas thorough analyses of 3D material micro-structure, air voids, width and curvature of shear...
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Thermodynamic Cycles of Air Microturbine Power Plants Working on Biomass Fuels
PublikacjaThe gas turbine engine is modified to work as an air turbine set which consists, in the simplest arrangement, of a compressor, a heat exchanger and a turbine. Air is a working medium for both: the compressor and the turbine. This kind of air turbine set can be applied in power plants working on biomass fuels. In this solution we can burn fuels of varying parameters in the external combustion chamber without any harmful effects...
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Compact broadband multi-way 1:6 power divider
PublikacjaThis paper introduces a design flow of a microstrip multi-way 1:6 power divider incorporating photonic bandgap (PBG) structures. Themethod proposed has enabled the achievement of considerable miniaturization (15%) together with transmission characteristics enhancement(141% bandwidth). Measured results show significant similarity to theoretical characteristics, which proves the attractiveness of presented design methodology.
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HIERARCHICAL CYCLES IN MODERN POWER SYSTEMS – EXERGY ANALYSIS UNDER PART LOADS
PublikacjaThe aim of the paper is to investigate thermodynamic efficiency of advanced hierarchic power cyclesunder partial loads by using of exergy analyze. Advanced hierarchical power systems arecomposed of few energy conversion cycles, most common are steam and gas cycles in various configurations, but they may contain fuel cells, ORC, lithium bromide absorption chillers and others. Moreover hierarchical cycles can be powered by several...
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Performance analysis of power swing blocking feature in ABB 670 series impedance relays
PublikacjaThis paper presents test results of a distance protection’s PSD power swing detection feature in ABB 670 series relays. A RED670 relay was tested, which is part of the hydroelectric set protection in Żarnowiec Pumped Storage Plant. The power swing blocking feature’s performance was analysed on the basis of the results of object tests made with an Omicron digital tester. Also presented are simulation results that illustrate the...
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Automatic tuning of a resonant circuit in wireless power supply systems for biomedical sensors
PublikacjaIn this paper, a tuning method of a resonant circuit suited for wireless powering of miniature endoscopic capsules is presented and discussed. The method allows for an automatic tuning of the resonant frequency and matching impedance of a full wave rectifier loading the resonant circuit. Thereby, the receiver tunes so as to obtain the highest power efficiency under given conditions of transmission. A prototype receiver for wireless...
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Market Structure and Market Power in Selected Sectors of The Polish Economy Based on COICOP Classification
PublikacjaThis paper present new and simple measures of market structure and market power. Based on the classical models of market structures, where a given structure is determined by the number of enterprises, indexes of degree of monopoly have been estimated, representing an average number of entities per branch. Additionally, market power indexes have been determined as an average revenue per an enterprise in a given branch. This approach...
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Performance/energy aware optimization of parallel applications on GPUs under power capping
PublikacjaIn the paper we present an approach and results from application of the modern power capping mechanism available for NVIDIA GPUs to the bench- marks such as NAS Parallel Benchmarks BT, SP and LU as well as cublasgemm- benchmark which are widely used for assessment of high performance computing systems’ performance. Specifically, depending on the benchmarks, various power cap configurations are best for desired trade-off of performance...
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HYBRID ENERGY SYSTEM FOR A CLASSIC SHIP POWER PLANT
PublikacjaThe article presents a brief overview of hybrid energy systems used on ships. The area of their application is outlined. The benefits of using such systems are also indicated. Then, the classic ship power plant is defined. The most important part of the article is a proposal how to modify a classic engine room by using a hybrid energy system. The idea is: to accumulate a part of electricity in areas where it is allowed to burn...
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Influence of Exhaust System Setup on Working Zone Pollution by Dust during Sawing of Particleboards
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Board cross-section errors while sawing on twin shaft multi-rip saws
PublikacjaW pracy przedstawiono wpływ warunków pracy pił na powstawanie błędów przecinania w postaci uskoku na przekroju poprzecznym tarcicy.
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Optimal selection of the sawdust separation device for a narrow-kerf sawing machine PRW15-M
PublikacjaW pracy przedstawiono granulometryczną analizę rozkładu wiórów i pyłu drzewnego otrzymanego w procesie przecinania suchych pryzm sosnowych na pilarce ramowej wielopiłowej PRW15-M. Wielkości wiórów mieściły się w granicach od 84,7 μm do nawet 14 mm. Te ostatnie są elementami będącymi efektem rozszczepiania dolnej powierzchni pryzmy przez wychodzące z niej ostrza piły. Większośc wiórów z najmniejszych frakcji ma postać sześciennych...
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Design of power cable lines partially exposed to direct solar radiation – special aspects
PublikacjaPower 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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Inlet air fogging of marine gas turbine in power output loss compensation
PublikacjaThe use of inlet air fogging installation to boost the power for gas turbine engines is widely applied in the power generation sector. The application of fogging to mechanical drive is rarely considered in the literature [1]. This paper will cover some considerations relating to its application to gas turbines in ship drive. There is an important evaporative cooling potential throughout the world when the dynamic data is evaluated,...
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Simulation of Protein Structure and Dynamics with the Coarse-Grained UNRES Force Field
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Adjustment for shape restoration and force control of cable arch stayed bridges
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An Approximate Linear Analysis of Structures Utilizing Incremental Loading of Force Method
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On the modelling of aerodynamic force coefficients for over-shroud seals of turbine stages
PublikacjaThis paper presents experimental investigations which made it possible to determine dynamic coefficients of labyrinth over-shroud seal of a model air turbine. The coefficients associate pressure forces with turbine rotor displacement, velocity and acceleration respective to turbine casing (linear model) and play important role in analyzing turbine-set dynamics. The obtained results indicated that involving serious errors can be...
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Efficient sampling of high-energy states by machine learning force fields
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The theoretical description of friction force in bio-joints as function of cartilage roughness
PublikacjaWartości sił tarcia w naturalnych stawach człowieka a szczególnie w endoprotezach stawu biodrowego rzutują na proces zużywania się powierzchni stawowych. Dlatego problem wyznaczania sił tarcia w biołożyskach jest bardzo istotny. W trakcie chodzenia mamy co najmniej ruch sferycznej powierzchni głowy w dwóch różnych kierunkach dla naturalnych i sztucznych stawów biodrowych człowieka. Dlatego też siły tarcia występują co najmniej...
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Impact force spectrum for damage assessment of earthquake-induced structural pounding
PublikacjaCelem artykułu jest zastosowanie spektrum siły zderzenia do szacowania zniszczeń powstałych na skutek zderzeń pomiędzy konstrukcjami budowlanymi, do których dochodzi podczas trzęsień ziemi. Wyniki analizy wskazują, iż spektrum takie może być przydatnym narzędziem przy projektowaniu konstrukcji podatnych na zderzenia. Przykłady spektrów odpowiedzi pokazują, iż zapewnienie odpowiedniej przerwy dylatacyjnej lub zgranie parametrów...
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Mechanical Properties of Single-Walled Carbon Nanotubes with AIREBO Force-Filed
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MARKAL long-term power generation scenarios for Poland - Concept of the model
PublikacjaIn this paper we have presented the concept of Polish MARKAL optimization model developed for the needs of power generation scenarios in long-term perspective i.e. by 2040. The depiction of Polish MARKAL with Reference Energy System structure was provided. In addition, basic model assumptions, energy technology database, projections of electricity demand and power plant ageing pathways were presented. Our goal is to test MARKAL...
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CFD-based evaluation of current-carrying capacity of power cables installed in free air
PublikacjaEvaluation of current-carrying capacity of power cables and selection of cross-sectional area of their conductors are mainly performed in accordance with requirements of EN, IEC or IEEE standards. However, these standards do not provide all methods of cables installation and location which occur in practice. Thus, in some cases, performance of advanced modeling of various thermal phenomena, affecting power cables current-carrying...
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Power and energy measurement problems in transmission line between Poland-Lithuania
PublikacjaThe paper discusses problem of power and energy metering in double circuit overhead transmission line. Considerations are based on example of transmission line connecting Polish substation Bis Elk and Lithuanian substation Alytus.
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Power augmentation of PGE Gorzow's gas turbine by steam injection - thermodynamic overview
PublikacjaThe impact of steam injection upon a gas turbine and a combined power plant performance has been investigated. This article describes and summarizes possibilities of modification for current gas turbine in PGE Gorzow power plant into the Cheng cycle. Our modification deals with a thermal cycle, in which steam produced in a heat recovery steam generator is injected into the gas turbine's combustion chamber. It has been proved that...
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Design and evaluation of a base module of active power electronic transformer
PublikacjaThis paper presents an active power electronic transformer (APET) based on modular structure. The proposed three phase APET consists of at least three base modules (BM). The input/output stage of the BM is based on half-bridge sub modules. The isolation stage includes a medium frequency transformer and is realized as a dual half-bridge. The paper describes construction process and explains the control strategy. The theoretical...
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Structure and the space vector modulation for a medium-voltage power-electronic-transformer based on two seven-level cascade H-bridge inverters
PublikacjaThis study presents the structure and the space vector pulse-width modulation (SVPWM) for power electronic transformer (PET) based on two seven-level cascade H-bridge (CHB) inverters. The DC links of CHB inverters are coupled with nine dual-active bridge (DAB) converters with medium-frequency transformers. The DC-link voltages are equalised with two methods – through the control of DAB voltages...
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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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Physical properties of homogeneous TiO2 films prepared by high power impulse magnetron sputtering as a function of crystallographic phase and nanostructure
PublikacjaOptical, photo-electrochemical, crystallographic and morphological properties of TiO2 thin films prepared by high power impulse magnetron sputtering at low substrate temperatures (<65 ◦C) without post-deposition thermal annealing are studied. The film composition-anatase, rutile or amorphous TiO2-is adjusted by the pressure (p ∼ 0.75-15 Pa) in the deposition chamber. The different crystallographic phases were determined with grazing...
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Damage Detection Strategies in Structural Health Monitoring of Overhead Power Transmission System
PublikacjaOverhead power transmission lines, their supporting towers, insulators and other elements create a highly distributed system that is vulnerable to damage. Typical damage scenarios cover cracking of foundation, breakage of insulators, loosening of rivets, as well as cracking and breakage of lines. Such scenarios may result from various factors: groundings, lightning strikes, floods, earthquakes, aeolian vibrations, conductors galloping,...
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A coupled constitutive model for fracture in plain concrete based on continuum theory with non-local softening and eXtended Finite Element Method
PublikacjaThe paper presents a constitutive model for concrete which combines a continuous and discontinuous fracture description. In a continuum regime, two different constitutive laws were used. First, a plasticity model with a Rankine failure criterion and an associated fl ow rule was used. Second, a constitutive law based on isotropic damage mechanics was formulated. In order to capture the width of a localized zone and to obtain mesh-independent...
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AC-DC-DC Converter for Small Power Energy Storage Systems
PublikacjaThe energy transformation driven by the development of renewable energy sources has become a reality for all power grid users. Prosumer energy, primarily utilizing photovoltaic installations, is one of the fastest-growing market segments. The advancement of technology, a decrease in electrochemical energy storage prices, and changes in the legal framework governing energy billing for grid-fed power have led to a growing interest...
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High Frequency Harmonics Emission of Modern Power Electronic AC-DC Converters
PublikacjaModern AC/DC converters with bidirectional power flow employing PWM boost topology generate harmonic distortions of input current in relatively high frequency range tightly related to modulation carrier frequency. These frequencies and its multiples in typical applications are usually located in frequency range from single up to several of kHz. Increased harmonic emission in this frequency range can easily and harmfully influence...
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Compensation of Dead Time Effects for Shunt Active Power Filters
PublikacjaThe paper presents a comprehensive approach to the compensation of the grid current distortion for shunt active power filter systems. Four different sources of current distortion are addressed: imperfect grid synchronization caused by the distortion in the grid voltages, time delays in the estimation of compensating currents and grid voltages, fluctuations of the dc bus voltage, and the distortion of inverter output voltages due...
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Small-scale passive emission chamber for screening studies on monoterpene emission flux from the surface of wood-based indoor elements
PublikacjaAnalysis of literature data published in the last fewyears leads to the conclusion that in the process of assessment of emission flux of organic compounds emitted from different types of equipment and finishing materials, new types of devices, among which small-scale passive emission chambers for the performance of in-situ research are designed and applied on a larger scale. These devices can be successfully used for the assessment...
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Computer-aided analysis of resonance risk in power system with Static Var Compensators
PublikacjaStatic Var Compensators operation in a power system may significantly improve voltage profiles in nodes and the reactive power balance, as well as ensure greater system stability in emergency conditions. However these devices may be a cause of a resonance in the system. The aim of this paper is to call attention to the need to include resonance phenomena in a compensator’s location evaluation process. The analysis performed in...
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Method of sum of power losses as a way for determining the ki coefficients of energy losses in hydraulic motor
PublikacjaThis paper shows application of the method of sum of power losses to determining energy losses which occur in hydraulic rotary motor in situation when not all laboratory data are at one’s disposal or when no use is made of data contained in catalogue charts. The method makes it possible to determine the coefficients ,ki , of energy losses occurring in the motor. The method of sum of power losses is based on the approach proposed...
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On the Possibilities of Decreasing Power Loss in Large Tilting Pad Thrust Bearings
PublikacjaJournal Menu About this Journal Abstracting and Indexing Aims and Scope Article Processing Charges Articles in Press Author Guidelines Bibliographic Information Citations to this Journal Contact Information Editorial Board Editorial Workflow Free eTOC Alerts Publication Ethics Submit a Manuscript Table of Contents Abstract Full-Text PDF Full-Text HTML...
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Optimization of Nuclear Power Share in the Structure of Electricity Production in Poland in Time Perspective by 2060
PublikacjaThe author of this paper presented the results of a system analysis using MARKAL model, aiming at the optimization of nuclear power share in power generation structure in Poland in time perspective by 2060. Optimization criterion is the minimization of the objective function, i.e. the total cost of energy system, taking into account constraints related to CO2, SOx and NOx emissions and obligatory shares of electricity from renewable...
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Technological and Media Platforms: Redefinition of Meanings as Symbolic Power over the Discourse
PublikacjaRedefining the meanings of such social terms as “likes” and “friends” on Facebook is a popular practice. In terms of consistency, the (auto)-redefinition of the term “platform” is itself particularly important from a media management perspective. The article proposes to consider the redefinition of meanings as a form of wielding non-transparent power over discourse. From this perspective, redefining a meaning is a form of holding...
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Single-phase power electronics transformer with active functions for smart grid
PublikacjaThis paper presents the control of one cell of a modular single-phase power electronics transformer with active functions for meeting the smart grid concept. In this way, the converter could be used not only as a conventional transformer but also for grid such as reactive power, harmonic elimination and energy storage. The topology of the cell is composed by a bidirectional converter with three stages: a half bridge in the input...
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A Power-Efficient Digital Technique for Gain and Offset Correction in Slope ADCs
PublikacjaIn this brief, a power-efficient digital technique for gain and offset correction in slope analog-to-digital converters (ADCs) has been proposed. The technique is especially useful for imaging arrays with massively parallel image acquisition where simultaneous compensation of dark signal non-uniformity (DSNU) as well as photo-response non-uniformity (PRNU) is critical. The presented approach is based on stopping the ADC clock by...
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Silicon Oxycarbide-Graphite Electrodes for High-Power Energy Storage Devices
PublikacjaHerein we present a study on polymer-derived silicon oxycarbide (SiOC)/graphite composites for a potential application as an electrode in high power energy storage devices, such as Lithium-Ion Capacitor (LIC). The composites were processed using high power ultrasound-assisted sol-gel synthesis followed by pyrolysis. The intensive sonication enhances gelation and drying process, improving the homogenous distribution of the graphitic...
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High-Power Jamming Attack Mitigation Techniques in Spectrally-Spatially Flexible Optical Networks
PublikacjaThis work presents efficient connection provisioning techniques mitigating high-power jamming attacks in spectrally-spatially flexible optical networks (SS-FONs) utilizing multicore fibers. High-power jamming attacks are modeled based on their impact on the lightpaths’ quality of transmission (QoT) through inter-core crosstalk. Based on a desired threshold on a lightpath’s QoT, the modulation format used, the length of the path,...
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Inverse and forward surrogate models for expedited design optimization of unequal-power-split patch couplers
PublikacjaIn the paper, a procedure for precise and expedited design optimization of unequal power split patchcouplers is proposed. Our methodology aims at identifying the coupler dimensions that correspond to thecircuit operating at the requested frequency and featuring a required power split. At the same time, thedesign process is supposed to be computationally efficient. The proposed methodology involves two typesof auxiliary models (surrogates):...
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Safety issues referred to induced sheath voltages in high-voltage power cables – case study
PublikacjaLoad currents and short-circuit currents in high-voltage power cable lines are sources of the induced voltages in the power cables’ concentric metallic sheaths. When power cables operate with single-point bonding, which is the simplest bonding arrangement, these induced voltages may introduce an electric shock hazard or may lead to damage of the cables’ outer non-metallic sheaths at the unearthed end of the power cable line. To...
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Design analysis of combined gas-vapour micro power plant with 30 kW air turbine
PublikacjaThe article presents basic results of the design analysis of a combined gas-vapour micro power plant with a waste-heat boiler without exhaust reheat, working in the vapour section in the Organic Rankine Cycle (ORC) system. The analysis concerned working media most frequently used in those types of power plants and planned to be used in future. The object of the analysis was a micro power plant with a 30 kW gas (air) turbine for...
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Design analysis of combined gas-vapour micro power plant with 30 kW air turbine
PublikacjaThe article presents basic results of the design analysis of a combined gas-vapour micro power plant with a waste-heat boiler without exhaust reheat, working in the vapour section in the Organic Rankine Cycle (ORC) system. The analysis concerned working media most frequently used in those types of power plants and planned to be used in future. The object of the analysis was a micro power plant with a 30 kW gas (air) turbine for...