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Electromagnetic Problems Requiring High-Precision Computations
PublikacjaAn overview of the applications of multiple-precision arithmetic in CEM was presented in this paper for the first time. Although double-precision floating-point arithmetic is sufficient for most scientific computations, there is an expanding body of electromagnetic problems requiring multiple-precision arithmetic. Software libraries facilitating these computations were described, and investigations requiring multiple-precision...
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GPU-Accelerated Finite-Element Matrix Generation for Lossless, Lossy, and Tensor Media [EM Programmer's Notebook]
PublikacjaThis paper presents an optimization approach for limiting memory requirements and enhancing the performance of GPU-accelerated finite-element matrix generation applied in the implementation of the higher-order finite-element method (FEM). It emphasizes the details of the implementation of the matrix-generation algorithm for the simulation of electromagnetic wave propagation in lossless, lossy, and tensor media. Moreover, the impact...
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An Analysis of Elliptical-Rectangular Multipatch Structure on Dielectric-Coated Confocal and Nonconfocal Elliptic Cylinders
PublikacjaA rigorous analysis of the resonance frequency problem of an elliptical-rectangular microstrip structure mounted on dielectric-coated elliptic conducting cylinder, with electrically small radius, is investigated in this paper. A full-wave analysis and a moment-method calculation are employed. The analysis is carried out considering the expansion of the field as a series of Mathieu functions. The complex resonance frequencies of...
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Calculation of the propagation loss in urban radio-access systems
PublikacjaZweryfikowano eksperymentalnie modele propagacyjne opracowane dla telefonii komórkowej w mieście, stosowane przy analizach projektowych systemów dostępowych. Przeprowadzono obszerne badania pomiarowe i zebrano prawie 19 tys. pomiarów. Na tej podstawie, stosując wielowymiarową analize regresji oraz zaproponowaną charakterystykę propagacyjną radiowych łączy dostępowych, opracowano nowy wielowariantowy model propagacyjny przeznaczony...
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Scattering From a Cylindrical Object of Arbitrary Cross Section With the Use of Field Matching Method
PublikacjaA simple and intuitive solution to scattering problems in shielded and open structures is presented. The main idea of the analysis is based on the direct field matching technique involving the usage of projection of the fields at the boundary on a fixed set of orthogonal basis functions. Different convex shapes and various obstacle materials are considered to verify the validity of the method in open and closed structures. The...
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Periodicity Matters: Grating or lattice resonances in the scattering by sparse arrays of subwavelength strips and wires.
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Hybrid technique for the analysis of circular waveguide junctions loaded with ferrite posts
PublikacjaThis study presents a hybrid technique for the analysis of circular waveguide junctions loaded with axially symmetrical ferrite posts of irregular shape. The method is based on a combination of the finite-difference frequency- domain technique with a mode-matching technique. The proposed approach is validated by comparing the presented results with numerical ones obtained from commercial software. The application of a cylindrical...
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Measurement of Coherence Bandwidth in UHF Radio Channels for Narrowband Networks
PublikacjaThis paper presents results of investigation on the coherence bandwidth of narrowband radio channels in 430MHz band. The coherence bandwidth values were estimated froma power delay profile obtained by recording CDMA2000 forward channel signals during real-fieldmeasurements in various environments:mediumcity, flat terrain, and hilly terrain in northern Poland.The results of measurements are compared with characteristic parameters...
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Accurate modelling of microwave structures using shape-preserving response prediction
PublikacjaArtykuł prezentuje metodologię dokładnego modelowania struktur mikrofalowych. Jest to zmodyfikowana wersja techniki opartej na procedurze przewidywania odpowiedzi z zachowaniem kształtu (shape-preserving response prediction, SPRP), która oszacowuje odpowiedź struktury mikrofalowej otrzymanej poprzez kosztowną obliczeniowo symulację elektromagnetyczną za pomocą taniego obliczeniowo modelu tejże struktury. Modyfikacja polega na wykorzystaniu...
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Accelerated simulation-driven design optimisation of compact couplers by means of two-level space mapping
PublikacjaIn this study, the authors discuss a robust and efficient technique for rapid design of compact couplers. The approach exploits two-level space mapping (SM) correction of an equivalent circuit model of the coupler structure under design. The first SM layer (local correction) is utilised to ensure good matching between the equivalent circuit and the electromagnetic model at the component level. Subsequent global correction allows...
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Rapid multi-objective design optimisation of compact microwave couplers by means of physics-based surrogates
PublikacjaThe authors introduce a methodology for fast multi-objective design optimisation of miniaturised microwave couplers. The approach exploits the surrogate-based optimisation paradigm with an underlying low-fidelity model constructed from an equivalent circuit of the structure under consideration, corrected through implicit and frequency space mapping. A fast prediction tool obtained this way is subsequently optimised by a multi-objective...
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Rapid simulation-driven design of miniaturised dual-band microwave couplers by means of adaptive response scaling
PublikacjaOne of the major challenges in the design of compact microwave structures is the necessity of simultaneous handling of several objectives and the fact that expensive electromagnetic (EM) analysis is required for their reliable evaluation. Design of multi-band circuits where performance requirements are to be satisfied for several frequencies at the same time is even more difficult. In this work, a computationally efficient design...
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Analytical Expression for the Time-Domain Green's Function of a Discrete Plane Wave Propagating in the 3-D FDTD Grid
PublikacjaIn this paper, a closed-form expression for the time-domain dyadic Green’s function of a discrete plane wave (DPW) propagating in a 3-D finite-difference time-domain (FDTD) grid is derived. In order to verify our findings, the time-domain implementation of the DPW-injection technique is developed with the use of the derived expression for 3-D total-field/scattered-field (TFSF) FDTD simulations. This implementation requires computations...
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Efficient Complex Root Tracing Algorithm for Propagation and Radiation Problems
PublikacjaAn efficient complex root tracing algorithm for propagation and radiation problems is presented. The proposed approach is based on a discretization of Cauchy’s Argument Principle and its generalization to the C × R space. Moreover, an engagement of the tracing process with a global root finding algorithm recently presented in the literature is performed. In order to confirm a validity and efficiency of the proposed technique, a...
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Propagation in the Open Cylindrical Guide of Arbitrary Cross Section With the Use of Field Matching Method
PublikacjaA simple solution to propagation problem in open waveguides and dielectric fibers of arbitrary convex cross section is presented. The idea of the analysis is based on the direct field matching technique involving the usage of the field projection at the boundary on a fixed set of orthogonal basis functions. A complex root tracing algorithm is utilized to find the propagation coefficients of the investigated guides. Different convex...
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Low-cost and reliable geometry scaling of compact microstrip couplers with respect to operating frequency, power split ratio, and dielectric substrate parameters
PublikacjaA technique for rapid re-design of miniaturised microstrip couplers with respect to operating conditions as well as material parameters of the dielectric substrate is proposed. The dimension scaling process is based on a set of pre-optimised reference designs, obtained for an equivalent circuit model of the coupler at hand. The reference designs are utilised to construct an inverse surrogate model which – upon suitable correction...
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Global Complex Roots and Poles Finding Algorithm Based on Phase Analysis for Propagation and Radiation Problems
PublikacjaA flexible and effective algorithm for complex roots and poles finding is presented. A wide class of analytic functions can be analyzed, and any arbitrarily shaped search region can be considered. The method is very simple and intuitive. It is based on sampling a function at the nodes of a regular mesh, and on the analysis of the function phase. As a result, a set of candidate regions is created and then the roots/poles are verified...
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Expedite EM-driven generation of Pareto-optimal trade-off curves for variable-turn on-chip inductors
PublikacjaThis work presents a novel approach to computationally efficient Pareto front identification for variable-turn on-chip inductors. The final outcome is a set of solutions that correspond to the best trade-offs between conflicting design objectives. Here, we consider minimising inductor area and, simultaneously, maximising its quality factor, while maintaining a specified inductance value at a given operating frequency. As opposed...
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Characterization of Slow and Fast Fading in Off-Body Communication at 2.45 GHz with Space Diversity Scheme in an Indoor Environment
PublikacjaThe characterization of slow and fast fading in wireless body area networks with space diversity scheme has been presented. The analysis, based on the measurements at 2.45 GHz in an indoor environment, has shown that for all investigated configurations of receiving wearable antennas, the correlation coefficient values of the received signals’ parameters are below the assumed value of 0.5, being close to zero for the vast majority...
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A Self-Adaptive Complex Root Tracing Algorithm for the Analysis of Propagation and Radiation Problem
PublikacjaAn improved complex root tracing algorithm for radiation and propagation issues is proposed. The approach is based on a self-adaptive discretization of Cauchy’s argument principle for a C × R space and requires a reduced number of function calls in comparison to other procedures presented in the literature. A few different examples concerning propagation and radiation problems have been considered to verify the validity and efficiency...
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Low-cost data-driven modelling of microwave components using domain confinement and PCA-based dimensionality reduction
PublikacjaFast data-driven surrogate models can be employed as replacements of computationally demanding full-wave electromagnetic simulations to facilitate the microwave design procedures. Unfortunately, practical application of surrogate modelling is often hindered by the curse of dimensionality and/or considerable nonlinearity of the component characteristics. This paper proposes a simple yet reliable approach to cost-efficient modelling...
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Variable-fidelity response feature surrogates for accelerated statistical analysis and yield estimation of compact microwave components
PublikacjaAccounting for manufacturing tolerances is an essential part of a reliable microwave design process. Yet, quantification of geometry and/or material parameter uncertainties is challenging at the level of full-wave electromagnetic (EM) simulation models. This is due to inherently high cost of EM analysis and massive simulations necessary to conduct the statistical analysis. Here, a low-cost and accurate yield estimation procedure...
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Communication Model Order Reduction in Hybrid Methods Involving Generalized Impedance Matrix
PublikacjaA novel strategy for the efficient analysis of frequency-domain scattering electromagnetic problems in open and closed domains is presented. A fully automatic model-order reduction technique, called the enhanced reduced-basis method, is applied to increase the efficiency of the hybrid approach, which combines the finite-element and mode-matching methods. Numerical tests show that the proposed algorithm yields reliable and highly...
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Rapid design of miniaturised branch-line couplers through concurrent cell optimisation and surrogate-assisted fine-tuning
PublikacjaIn this study, the authors introduce a methodology for low-cost simulation-driven design optimisation of highly miniaturised branch-line couplers (BLCs). The first stage of their design approach exploits fast concurrent optimisation of geometrically dependent, but electromagnetically isolated cells that constitute a BLC. The cross-coupling effects between the cells are taken into account in the second stage, where a surrogate-assisted...
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Measurement Stand and Methodology for Research of the Off-Body and Body-to-Body Radio Channels in WBANs with Different Diversity Schemes
PublikacjaThe concept of an experimental test bed for system loss and channel impulse response measurements for off-body and body-to-body radio channels in wireless body area networks (WBANs) is fully described. The possible measurement scenarios that may occur in investigation of off-body and body-to-body channels are classified and described in detail. Additionally, an evaluation is provided of the standard and expanded uncertainties of...
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Resolving conflicts in object tracking for automatic detection of events in video
PublikacjaAn algorithm for resolving conflicts in tracking of moving objects is presented. The proposed approach utilizes predicted states calculated by Kalman filters for estimation of trackers position, then it uses color and texture descriptors in order to match moving objects with trackers. Problematic situations, such as splitting objects, are addressed. Test results are presented and discussed. The algorithm may be used in the system...
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Multi-objective optimization of expensive electromagnetic simulation models
PublikacjaVast majority of practical engineering design problems require simultaneous handling of several criteria. For the sake of simplicity and through a priori preference articulation one can turn many design tasks into single-objective problems that can be handled using conventional numerical optimization routines. However, in some situations, acquiring comprehensive knowledge about the system at hand, in particular, about possible...
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MUTL PROTEIN AS A COMMON CONSTITUENT OF VSP, BER, NER AND MMR REPAIR SYSTEMS
PublikacjaMutS and MutL proteins are renowned mostly for their functions in well-characterized, post-DNA replication mismatch repair system (MMR). However, there is growing evidence that MMR system is not the only field of action of these proteins. Moreover, involvement in MMR does not even have to be their primary function. There are some reports indicating involvement of MutL in BER, NER and VSP (very short patch repair). MutL protein...
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BADANIA SYMULACYJNE PROWADZONE W ŚRODOWISKU SYSTEMU EKSPERTOWEGO STOSOWANE DO WSPOMAGANIA PROJEKTOWANIA UKŁADÓW AUTOMATYKI STATKU
PublikacjaW referacie przedstawiono wykorzystanie badań symulacyjnych jako źródła wiedzy dla systemu ekspertowego. Omawiany system służy wspomaganiu doboru elementów steru strumieniowego. Elementami tego systemu są: biblioteka struktur, biblioteka modeli, baza elementów oraz baza wiedzy. Jako przykład przedstawiono badania symulacyjne struktury steru strumieniowego zawierającej silnik indukcyjny, wał śrubowy, śrubę o skoku nastawnym oraz...
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Macromodels for Efficient Analysis of Open-Region Problems Using the Finite Element Method
PublikacjaThis paper presents a local model-order reduction, called macromodeling, applied to speed-up the simulations of open-region problems, analyzed by means of finite element method. This technique is illustrated by a numerical example, which deals with a dielectric resonator antenna (DRA). The obtained results show that the proposed approach is reliable and can significantly increase the standard finite element method efficiency.
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O możliwości upraszczania obliczeń na wstępnych etapach projektowania elektrowni statków towarowych
PublikacjaW referacie przedstawiono uproszczoną metodę określania zapotrzebowania na energię elektryczną w określonych stanach eksploatacji statków towarowych, celem doboru wiel-kości i ilości `źródeł energii elektrycznej. Metoda może być stosowana na wstępnych eta-pach projektowania siłowni okrętowych.
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Energy roadmaps for the city of Gdańsk
PublikacjaThe paper presents energy roadmaps for Gdansk in three time perspectives: short-term (the year 2012), medium-term (2020) and long-term (2050). The paper is a result of the research carried out under the PATH-TO-RES project, supported by European Commission programme SAVE Altener Intelligent Energy Europe.
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Lexicon Based Algorithm for Domain Ontology Merging and Alignment
PublikacjaMore and more systems contain some kind of knowledge describing their field of operation. Such knowledge in many cases is stored as an ontology. A need arises for ability to quickly match those ontologies to enable interoperability of such systems. The paper presents a lexicon based algorithm for merging and aligning of OWL ontologies. The proposed similarity levels are being presented and the proposed algorithm is being described....
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The impact of precipitation and external carbon source addition on biological nutrient removal in activated sludge systems - experimentalinvestigation and mathematical modeling
PublikacjaThe aim of this study was to determine the effects of chemical precipitation and addition of external carbonsources on the denitrification capability and enhanced biological phosphorus removal (EBPR) interactions atthe 'Wschod' WWTP (600,000 PE) in Gdansk (northern Poland). For this purpose, different kinds of batch experimentswere carried out with the settled wastewater (without pretreatment and after coagulation-flocculation)and...
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The impact of precipitation and external carbon source addition on biological nutrient removal in activated sludge systems – experimental investigation and mathematical modeling
PublikacjaThe aim of this study was to determine the effects of chemical precipitation and addition of external carbonsources on the denitrification capability and enhanced biological phosphorus removal (EBPR) interactions atthe ‘Wschod’ WWTP (600,000 PE) in Gdansk (northern Poland). For this purpose, different kinds of batch experimentswere carried out with the settled wastewater (without pretreatment and after coagulation-flocculation)and...
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Advantages of the Application of the Temper Bead Welding Technique During Wet Welding
PublikacjaThermo-mechanically rolled S460ML steel was chosen for welding in underwater wet welding conditions by covered electrodes. The main aim of this study was to check the weldability for fillet welds in a water environment by controlled thermal severity (CTS) tests and to check the influence of temper bead welding (TBW) on the weldability of the investigated steel. Non-destructive and destructive tests showed that S460ML steel has...
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Heat transfer enhancement of modular thermal energy storage unit for reversible heat pump cooperation
PublikacjaThe following article presents experimental comparison research on a hexagonal shelland-tube latent thermal energy storage (TES). Such shape of a shell was deliberately chosen instead of a cylindrical one due to its high modularity and with intent for future applications in automobiles (EV and PHEV) air conditioning systems (HVAC). Two geometries of helical coils, acting as tubes, were studied in this article. One was a simple...
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Provisioning Concepts for the Future Internet IIP Initiative
PublikacjaArtykuł prezentuje strategię wymiarowania zasobów sieci dla architektury Internetu Przyszłości zwanego Systemem IIP. Opisuje również relację zasad wymiarowania sieci w odniesieniu do metod zarządzania siecią. Opisane są dwie proponowane metody wymiarowania wraz niezbędnymi danymi wejściowymi. Pierwsze podejście stanowi problem optymalizacyjny z funkcją celu minimalizacji całkowitego poboru mocy. Drugie rozwiązanie bazuje na podejściu...
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Multi-objective optimization of microwave couplers using corrected domain patching
PublikacjaPractical design of microwave components and circuits is a compromise between various, often conflicting objectives. In case of compact structures, the trade-offs are typically concerned with the circuit size and its electrical performance. Comprehensive information about the best possible trade-offs can be obtained by means of multi-objective optimization. In this paper, we propose a computationally efficient technique for identifying...
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Exploiting multi-interface networks: Connectivity and Cheapest Paths
PublikacjaLet G = (V,E) be a graph which models a set of wireless devices (nodes V) that can communicate by means of multiple radio interfaces, according to proximity and common interfaces (edges E). The problem of switching on (activating) the minimum cost set of interfaces at the nodes in order to guarantee the coverage of G was recently studied. A connection is covered (activated) when the endpoints of the corresponding edge share at...
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Characterization of slow and fast fading in off-body communication at 2.45 GHz with space diversity scheme in indoor environment
PublikacjaThe characterization of slow and fast fading in Wireless Body Area Networks with space diversity scheme has been presented. The analysis, based on the measurements at 2.45 GHz in indoor environment, has shown that for all investigated configurations of receiving wearable antennas the correlation coefficient values of received signals’ parameters are below the assumed value of 0.5, being close to zero for the vast majority of cases. It...
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The impact of slowly biodegradable organic compounds on the oxygen uptake rate in activated sludge systems
PublikacjaThe hydrolysis process of slowly biodegradable substrate (Xs) have impact on the efficiencies of nutrient removal in activated sludge systems. Measurement of OUR and corresponding COD is accepted as a very useful tool to reflect the consumption of biodegradable substrates. The influence of the readily biodegradable substrate (Ss) in biological wastewater treatment systems has been extensively investigated, but little is known about...
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The impact of slowly biodegradable organic compounds on the oxygen uptake rate in activated sludge systems
PublikacjaThe hydrolysis process of slowly biodegradable substrate (Xs) have impact on the efficiencies of nutrient removal in activated sludge systems. Measurement of OUR and corresponding COD is accepted as a very useful tool to reflect the consumption of biodegradable substrates. The influence of the readily biodegradable substrate (Ss) in biological wastewater treatment systems has been extensively investigated, but little is known about...
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A distillery by-product as an external carbon source for enhancing denitrification in mainstream and sidestream treatment processes
PublikacjaThe use of fusel oil as an 'alternative' carbon source for denitrification in the mainstream and sidestream treatment processes was studied. Research comprised two kinds of batch experiments as well as acclimation of process biomass to external carbon sources. In the conventional nitrate utilization rate (NUR) measurements (one-phase experiments with non-acclimated biomass), the NUR with fusel oil was 1.4-1.7 g N/(kg VSS•h which...
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"Numeryczna symulacja pracy gazowego kotła wodnego raz ocena jego wpływu na środowisko"
PublikacjaIlość dostarczanego powietrza oraz rozkład jego koncentracji w komorze paleniskowej mają istotny wpływ na prawidłowość przebiegu procesu spalania. Uzyskanie jednorodnego rozkładu jest praktycznie niemożliwe, dlatego powietrze dostarczane jest w nadmiarze. Konieczne jest jednak dobranie takiej wartości współczynnika nadmiaru powietrza, która pozwoli ograniczyć stratę wylotową, utrzymując przy tym wartości emisji na możliwie niskim...
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Numeryczna symulacja pracy gazowego kotła wodnego oraz ocena jego wpływu na środowisko
PublikacjaIlość dostarczanego powietrza oraz rozkład jego koncentracji w komorze paleniskowej mają istotny wpływ na prawidłowość przebiegu procesu spalania. Uzyskanie jednorodnego rozkładu jest praktycznie niemożliwe, dlatego powietrze dostarczane jest w nadmiarze. Konieczne jest jednak dobranie takiej wartości współczynnika nadmiaru powietrza, która pozwoli ograniczyć stratę wylotową, utrzymując przy tym wartości emisji na możliwie niskim...
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"Numeryczna symulacja pracy gazowego kotła wodnego oraz ocena jego wpływu na środowisko"
PublikacjaIlość dostarczanego powietrza oraz rozkład jego koncentracji w komorze paleniskowej mają istotny wpływ na prawidłowość przebiegu procesu spalania. Uzyskanie jednorodnego rozkładu jest praktycznie niemożliwe, dlatego powietrze dostarczane jest w nadmiarze. Konieczne jest jednak dobranie takiej wartości współczynnika nadmiaru powietrza, która pozwoli ograniczyć stratę wylotową, utrzymując przy tym wartości emisji na możliwie niskim...
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Zastosowanie techniki ściegu odpuszczającego do spawania mokrego
PublikacjaW artykule przedstawiono zastosowanie techniki ściegu odpuszczającego do poprawy właściwości złączy ze stali konstrukcyjnych wykonywanych w warunkach mokrego spawania pod wodą. Scharakteryzowano spawanie mokre elektrodami otulonymi zmiany struktury i właściwości złączy spawanych przez nakładanie ściegów odpuszczających. Przedstawiono metodykę oraz wyniki badań metalograficznych i twardości próbek ze stali konstrukcyjnej o podwyższonej...
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Properties and interpretation of Instantaneous Complex Frequency
PublikacjaThe concept of Instantaneous Complex Frequency (ICF) was first defined by Lindon and developed mainly in works of two authors S. Hahn and M. Rojewski. Although it is not widely used in signal analysis, ICF was already used as a complex signal representation in the verification of handwritten signatures, pitch estimation, symbol timing recovery in PSK receiver and in detection of anomalies in data transmission. It should be noted,...
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Proposal of a System Loss Model for Body Area Network in Passenger Ferry Environment
PublikacjaIn the paper, proposal of an empirical off-body system loss model for Body Area Networks working in a passenger ferry environment at 2.45 GHz has been presented. The measurements were carried out for dynamic scenarios in the discotheque passenger ferry environment. The general model formula consists of three components: mean system loss, attenuation resulting from the variable antenna position on the human body, and attenuation...