Filters
total: 2983
filtered: 2212
displaying 1000 best results Help
Search results for: CURRANTS
-
A predictive estimation based control strategy for a quasi-resonant dc-link inverter
PublicationIn this paper the predictive estimation based control strategy for a quasi-resonant dc link inverter (PQRDCLI) is developed. Instead of direct measurement of dc link input inverter current – its estimation with one step prediction is applied. The PQRDCLI fed induction motor, controlled with a predictive current estimation stabilized inverter output voltage slopes independently of load. Moreover, reduction of overvoltage spikes...
-
Electric shock hazard in circuits with variable-speed drives
PublicationThe conventional approach to electrical safety under fault condition in typical power systems considers earth fault currents of sinusoidal waveform and frequency of 50/60 Hz. However, in circuits with variable-speed drives, there is earth fault current flow with harmonics, and these harmonics influence the threshold of ventricular fibrillation. The paper presents earth fault current waveforms in circuits with variable-speed drives...
-
Dynamics of fault arc traveling along busbars in high voltage switchboards = Dynamika łuku zwarciowego przemieszczającego się wzdłuż szyn rozdziel-nic wysokiego napięcia
PublicationThe paper presents the results of magnetic induction and electrodynamic force calculations acting on arc column during short-circuit in medium voltage air-insulated bus-bars. The gap between the bars was 120 mm and the prospective short-circuit currents ranged from 4 kA to 8 kA. The paper also shows the measurement results of average velocity fault arc depending on currents arc diameter and arc current was established and described....
-
Indeksy demokracji i stan zaawansowania ich rozwoju dla pomiaru jakości demokracji na poziomie lokalnym - Democracy indices and current state of their advancement for measuring quality of democracy at a local level
PublicationJak mierzyć demokrację? Jak ocenić, czy jeden ustrój demokratyczny jest bardziej de-mokratyczny od innego i na jakiej podstawie to stwierdzić? Pomiary jakości demokracji na poziomie państw istnieją już od 1946 roku, a na ich podstawie powstawały indeksy demokracji jak np. Freedom House, Polity IV, czy też Varieties of Democracy. Poza poziomem państw jest zdecydowanie mniej narzędzi tego typu, a istniejące – jak np. Local Autonomy...
-
O zastosowaniu metody prądów wirowych do technicznego pomiaru własności elektrycznych i magnetycznych metali = About application of eddy current method for technical measurement of electric and magnetic properties of metals
PublicationOpisano wyniki badań nad wykorzystaniem efektu prądów wirowych do badania własności elektrycznych i magnetycznych metali. Badania wykonano za pomocą sondy różnicowej. Wyniki pomiarów zależności częstotliwościowej wykonane dla modelowych materiałów porównano z wynikami modelowania metodą elementów skończonych.
-
Double Fed Induction Machine Drives
PublicationContents of the Chapter 22:Machine model.Properties of the DFM.Steady state machine operation.Control rules and decoupled control.Decoupling based on MM machine model.Decoupling based on vector model.Decoupling based on rotor current equation.Overall control system.Control system based on MM model.Control system based on vector model.Estimation of variables.Calculation of the angle between stator and rotor.Remarks about digital...
-
Implementation of power transformer controlled switching algorithm
PublicationThe article presents two new algorithms of controlled switching the power transformer. The main aim of the paper is to obtain formulas that determine the moments of closing of the circuit breaker poles. The study contains projects of control systems for both algorithms. Mathematical formulas for the time instants of the breaker poles closing were developed on the basis of electric circuit theory and magnetic circuit theory. The...
-
Selection of C-Type Filters for Reactive Power Compensation and Filtration of Higher Harmonics Injected into the Transmission System by Arc Furnaces
PublicationThis article presents a method for selecting the elements of a C-type filter working with a conventional LC-type filter for compensating reactive power and filtering out higher harmonics generated by arc furnaces and ladle furnaces. The study was conducted in a steel mill supplied by a 110 kV transmission system, where higher harmonic currents and nonlinear loads were measured. A series of computer simulations were performed under...
-
Impulse Impedance Measurements of Lightning Protection Earthings
PublicationLightning protection earthing systems should be tested at currents with time parameters similar to those of lightnings. A method and definition of a measured value of impulse impedance are introduced. The impulse impedance was determined by a quotient of voltage drop on the tested earthing to a value of current in measure circuit. The usefulness of the impulse method for lightning protection evaluation is tested on radio base stations...
-
EMI mitigation of GaN power inverter leg by local shielding techniques
PublicationThis paper presents local shielding techniques applied to a half-bridge inverter leg with the aim to reduce the common mode (CM) current noise at converter’s DC input. The research study is conducted for 650V Enhancement mode Gallium Nitride (GaN) power transistor switches. Main contributors of parasitic capacitances referred to the inverter-leg middle point node are identified. Then, shielding solutions are proposed to reduce...
-
ANALIZA WPŁYWU NIEJEDNOCZESNOŚCI ZAMYKANIA BIEGUNÓW ŁĄCZNIKA NA PRĄDY ZAŁĄCZENIOWE TRANSFORMATORA W STANIE JAŁOWYM
PublicationW artykule przedstawiono wyniki obliczeń symulacyjnych prądów załączeniowych transformatora dla różnych sekwencji zamykania biegunów łącznika. Sekwencje różniły się kolejnością łączenia faz oraz czasami opóźnienia w zamykaniu biegunów. Rozważono także kilka wariantów stanu namagnesowania szczątkowego rdzenia. Na podstawie analizy wyników stwierdzono, że przy jednoczesnym zamykaniu biegunów łącznika, właściwy dobór chwili załączenia...
-
Detection and time/frequency analysis of electric fields in the ground
PublicationThis paper sets out to detect and characterize electric fields in the ground (such as stray current fields) using a tandem time/frequency method of signal analysis. Results were obtained from investigations performed in the presence of a generated electric field with controlled variable characteristics, and in the presence of an electric field generated by a tramline. The analysis of measurement registers was performed using Short‐Time...
-
Application of Illuminating Modes concept in modal expansion of elliptical resonator
PublicationIn the paper an IlluminatingModes (IM) approach as an extension of Spectral Domain Approach (SDA) is presented. IM concept is applied to the case of open microstrip planar elliptical resonator. A modal expansion of currents induced in the structures during illuminating them by a single plane wave is the novelty of the method. As an example of application of the method, we present the results obtained by an examination of two resonators...
-
Energy losses reduction in the medium voltage cable line – case study
PublicationThe paper presents an analysis of energy losses in a power cable system, which is composed of two 30 kV cable lines. This cable system is located at the seaside holiday area, so the load profile during a year is specific. Energy losses related to reactive power transmission, as well as to currents induced in the sheaths of the cables, are subject to analysis. Measurements were made in the system in order to prepare a computer model...
-
Multiple reference frame theory in the synchronous generator model considering harmonic distortions caused by nonuniform pole shoe saturation
PublicationThe paper describes a synchronous generator model developed based on the multiple reference frame theory. The main physical phenomena included in the model are the machine armature non-sinusoidal voltage waveform and the influence of armature current in load conditions on the armature voltage waveform higher harmonic components. The modified multiple reference frame theory model is proposed. In this modified theory model the field...
-
Safety issues referred to induced sheath voltages in high-voltage power cables – case study
PublicationLoad 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...
-
Prądy łożyskowe w układach napędowych z silnikami indukcyjnymi
PublicationW pracy przedstawiono problemy występujące w układach napędowych z silnikami indukcyjnymi zasilanymi z falownika napięcia. Zwrócono uwagę na rosnącą liczbę uszkodzeń silników w napędach przekształtnikowych. Wskazano przyczyny wynikające z charakteru zasilania przekształtnikowego silnika. Główną uwagę poświęcono prądowi łożyskowemu, który odpowiada za większość awarii maszyn. Przedstawiono rodzaje prądów łożyskowych, wyjaśniając...
-
Badanie wybranych właściwości wyłączników różnicowoprądowych typu F
PublicationW instalacjach elektrycznych niskiego napięcia instaluje się coraz więcej przekształtników energoelektronicznych (systemy fotowoltaiczne, instalacje ładowania pojazdów elektrycznych, układy napędowe o regulowanej prędkości obrotowej silnika), a mają one wpływ na dobór typu wyzwalania wyłączników różnicowoprądowych (AC, A, F lub B). W obwodach, w których pojawia się prąd różnicowy zawierający składowe o częstotliwości innej niż...
-
A subdomain model for armature reaction field and open‐circuit field prediction in consequent pole permanent magnet machines
PublicationIn this paper, the machine quantity, such as electromagnetic torque, self and mutual inductances, and electromotive force, is analytically calculated for non-overlapping winding consequent pole slotted machine for open-circuit field and armature reaction. The sub-domain approach of (2-D) analytical model is developed using Maxwell's equations and divide the problem into slots, slot-openings, airgap and magnets region, the magnet...
-
Trends in Locally Balanced Energy Systems without the Use of Fossil Fuels: A Review
PublicationIn recent years, the idea of the operation of energy systems (power systems, heating systems) has changed significantly. This paper is an overview of locally balanced energy systems without the use of fossil fuels. The paper justifies the concept of local energy balancing in a new energy system that does not use fossil fuels (coal, natural gas, and crude oil), based on European Union guidelines and formal documents as well as the...
-
Induction machine model for current diagnostics of bearings. W: [CD-ROM]Proceedings and our Portrait. 48 Internationales Wissenschaftliches Kollo- quium. Ilmenau, 22.-25.09.2003. Ilmenau: Tech. Univ. Ilmenau**2003 s. [1-9] 8 rys. Model maszyny indukcyjnej dla prądowej diagnostyki łożysk.
PublicationPojawienie się określonych typów uszkodzeń w silniku jest źródłem odkształ-cenia tego prądu. Poddając przebieg prądu analizie widmowej obserwuje sięszereg składowych, które związane są z określonymi typami uszkodzeń. Referatprezentuje rezultaty badań modelowych i eksperymentalnych. Badania przepro-wadzono na silniku 1,1 kW czterobiegunowym. Zaprezentowany model pozwala za-równo na wprowadzanie wibracji wirnika jak ekscentryczności...
-
Analytical modeling of electric drives for vehicle traction control systems
PublicationWheel-torque control bandwidth in vehicle dynamics model is crucial in evaluating optimal tracking ability of tire slip and in analysis of control system stability. Electric drives’ control dynamics are influenced by timing of digital control events, e.g. by sampling instant of motor currents. Reflecting this timing in drive analytical models is therefore important for analysis of vehicle traction systems. The paper considers five...
-
Impact assessment culture in the European Union. Time for something new?
PublicationCurrent approaches and cultures for the economic evaluations of environmental and health policies may suffer from excessive reliance on a standard neoclassic economic toolbox that neglects alternative perspectives. This may prematurely limit the spectrum of available policy options. Here we show how the inclusion of neglected currents of thought such as non-Ricardian economics, bioeconomics and a set of qualitative-quantitative...
-
Safety at railway level crossings and Vision Zero
PublicationIn this work, safety analysis at the railway level crossings is presented using advanced mathematical modelling. Resistivity of track subgrade panels is taken into account. The analysis does not refer to the assessment of the current regulations. Specific cases of generalized dynamic system are considered by introducing operations S=Δ, S=P defined in space C(N) of real sequences. In this model, generalized discrete exponential...
-
System of protection against electric shock for circuits with power electronics converters
PublicationModern low voltage circuits are very often equipped with power electronics converters, therefore in these circuits non-sinusoidal earth currents (touch currents) may occur. For non-sinusoidal currents safety criteria should be modified. This paper presents these modified criteria and a computer system of protection against electric shock which can be implemented in circuits with power electronics converters. The system is based...
-
Photovoltaic phenomena in devices with perfluorozincphthalocyanine layer
PublicationThe course of photovoltaic phenomenon in organic photovoltaic cells utilizing thin layers of perfluorozincphthalocyanine was studied in few single and planar bilayer configurations. Mechanisms of photogeneration and recombination of free charge carriers were determined and active interfaces were localized. In case of single layer cells these interfaces were located at the front electrode/F16ZnPc junctions, whereas photogeneration...
-
Cross-Bonding of MV Cable Lines for Energy Losses Decrease
PublicationCurrently, almost all medium voltage cable lines (MV) operate with the return wires earthed at both ends of the cable. Such a way of operation causes that during normal states of operation as well as during disturbances, e.g. short-circuits, in the return wires induce currents whose values mainly depend on the currents flowing in the phase wires. These currents in normal operating states are a source of additional energy losses...
-
Nowa metoda obliczania rozpływu prądów zwarciowych w przewodach odgromowych linii wysokiego napięcia
PublicationReferat przedstawia nowatorską metodę obliczania wartości prądów płynących w przewodach odgromowych w czasie zwarć, pozwalającą na dobór przewodów odgromowych pod względem wytrzymałości cieplnej. Proponowana metoda charakteryzuje się większą dokładnością i większą uniwersalnością niż powszechnie stosowane metody, pozwalając tym samym na dobór przewodów odgromowych z mniejszym ryzykiem niepewności. Prezentowana metoda obliczeniowa...
-
CM Voltage Compensators for Power Electronic Interfaces
PublicationThe experimental results presented in the paper have shown that the application of the PEIs might cause EMC related problems, especially in the case of the application of a group of connected converters. The most convenient way to reduce EMI currents and prevent aggregation of EMI currents introduced by a group of converters is through passive compensation of voltage interference sources inside of the single converters. In the...
-
Cascaded Buck Hybrid Interlink Converter for Multiple-Input / Multiple-Output Operation
PublicationThe provision of isolated- and non-isolated DC output voltages by Power electronics power-conditioning devices in the recent ‘green-energy-revolution’ era is on course. In this paper, a structure for multi-input multi-output(MIMO) DC–DC buck converter is proposed to generate output voltages of varying levels with fewer component-count. The DC output voltage of each of the constituting buck converters can be used independently or...
-
Voltage Control of a Stand-Alone Multiphase Doubly Fed Induction Generator
PublicationThis article presents a multiphase doubly fed induction generator (MDFIG) with a dedicated and unique control algorithm in a stand-alone wind energy conversion system. The algorithm has been developed and elaborated in the case of different emergency modes. Compared with the traditional double-fed induction generator, the MDFIG has increased reliability, reduced current level per phase, and low rotor harmonic currents. The control...
-
Age, frequency of volunteering, and Present-Hedonistic time perspective predict donating items to people in need, but not money to combat COVID-19 during lock-down
PublicationRestrictions due to COVID-19 necessitated staying at home, but in some cases, encouraged charitable behavior, e.g., donating items to people in need (e.g., clothes, food), or money to support combatting COVID-19. Drawing on the previous findings regarding helping during disastrous situations and roles of time perspective in helping behaviors, the study tested the predictive value of age, gender, previous volunteering, altruistic...
-
Belief in the importance of socially responsible behaviors – the significance of trust and personal experiences with COVID-19
PublicationA vast number of studies have shown that trust is related to socially desirable traits and behaviors. In the present research we have investigated the relationship between generalized trust and beliefs about the importance of socially responsible behaviors (SRB) during the pandemic – namely, following the sanitary regime and getting vaccinated. Basing on the previous findings we assumed that trustful people...
-
Applications of Graphene-based Materials in Chromatography and Sample Preparation: A Review
Publication -
Ribosomal intergenic spacer analysis as a tool for monitoring methanogenic archaea changes in an anaerobic digester
PublicationThe applicability of a newly-designed PCR primer pair in examination of methanogenic Archaea in a digester treating plant biomass was evaluated by Ribosmal Intergenic Spacer Analysis (RISA). To find a suitable approach, three variants of RISA were tested: (1) standard, polyacrylamide gel-based, (2) automated, utilized capillary electrophoresis (GA-ARISA), and (3) automated microfluidics-based (MF-ARISA). All three techniques yielded...
-
Belief in a zero-sum game and subjective well-being across 35 countries
Publication -
De-gender them! Gendered vs cooperative division of housework – cross-cultural comparison of Polish and Norwegian students
Publication -
De-gender them! Gendered vs cooperative division of housework – cross-cultural comparison of Polish and Norwegian students
Publication -
[18F]Amylovis as a Potential PET Probe for β-Amyloid Plaque: Synthesis, In Silico, In vitro and In vivo Evaluations
Publication -
Which is Better in Fat Times and in Lean Times: the Macho Man vs. the Nice Guy? Priming Effects on Polish and Norwegian Students’ Mate Preferences
Publication -
Emotional Distress Associated with Surgical Treatment and its Relationship with Coping Profiles Among Chronically ill Older Patients
Publication -
Probiotic Bacteria: A Promising Tool in Cancer Prevention and Therapy
Publication -
Experience-based knowledge increases confidence in discriminating our memories
Publication -
In-Syringe Dispersive Liquid-Liquid Microextraction Coupled with High- Performance Liquid Chromatography for Trace Analysis of Naphthalene Sulfonates in Seawater
Publication -
Who cares for the environment? Pro-environmental and political opinions in relation to basic psychological needs. A person-centered approach
Publication -
Toward an understanding of occupational burnout among employees with autism – the Job Demands‑Resources theory perspective
PublicationThis article aims to gain insight into the phenomenon of occupational burnout among employees with autism based on the theoretical framework of the Job Demands-Resources theory and the literature on employees with autism in the workplace. Firstly, we argue that although the resources and demands of the neurotypical and neurodivergent employees might be different, the theoretical mechanism of occupational burnout formation remains...
-
Distinct hippocampal-prefrontal neural assemblies coordinate memory encoding, maintenance, and recall
PublicationShort-term memory enables incorporation of recent experience into subsequent decision-making. This processing recruits both the prefrontal cortex and hippocampus, where neurons encode task cues, rules, and outcomes. However, precisely which information is carried when, and by which neurons, remains unclear. Using population decoding of activity in rat medial prefrontal cortex (mPFC) and dorsal hippocampal CA1, we confirm that mPFC...
-
Therapeutic Potential of Multifunctional Tacrine Analogues
PublicationTacrine is a potent inhibitor of cholinesterases (acetylcholinesterase and butyrylcholinesterase) that shows limiting clinical application by liver toxicity. In spite of this, analogues of tacrine are considered as a model inhibitor of cholinesterases in the therapy of Alzheimer’s disease. The interest in these compounds is mainly related to a high variety of their structure and biological properties. In the present review, we...
-
Rehabilitation device supporting active and passive upper limb exercises
PublicationThis article presents a mechatronic solution for rehabilitation devices supporting active and passive exercises in persons with motor dysfunctions of the upper limbs in the area of the elbow and shoulder joints. A planar positioner integrated with original software and a control system, served as the basis for creating the present solution. Bellman’s programming method was applied to optimize the motion trajectory of the planar...
-
Direct brain stimulation modulates encoding states and memory performance in humans
PublicationPeople often forget information because they fail to effectively encode it. Here, we test the hypothesis that targeted electrical stimulation can modulate neural encoding states and subsequent memory outcomes. Using recordings from neurosurgical epilepsy patients with intracranially implanted electrodes, we trained multivariate classifiers to discriminate spectral activity during learning that predicted remembering from forgetting,...