Filtry
wszystkich: 1417
wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: propagation of ornamental plants
-
Influence of Phosphorus Speciation on Its Chemical Removal from Reject Water from Dewatering of Municipal Sewage Sludge
PublikacjaThe aim of the presented research was the assessment of phosphorus speciation impact on the precipitation of phosphorus in reject water using Ca(OH)2. To achieve this, phosphorus speciation (organic and inorganic phosphorus in suspension and in dissolved form) in reject water that is produced during sludge dewatering, after methane digestion in wastewater treatment plants (WWTPs), was determined. This study covered the materials...
-
Manufacturing and Recycling Impact on Environmental Life Cycle Assessment of Innovative Wind Power Plant Part 1/2
PublikacjaWind power plants are considered as ecologically-clean source of energy. However, manufacturing processes cannot be treated that way. Manufacturing processes consume huge amount of electrical and thermal energy and significant amount of materials, e.g. steel, polymers, oils and lubricants. All of the above could be potentially harmful for environment. There are not many works and publications regarding life-cycle analysis of wind...
-
Modelling Long‐Term Transition from Coal‐Reliant to Low‐Emission Power Grid and District Heating Systems in Poland
PublikacjaEnergy systems require technological changes towards climate neutrality. In Poland, where the power system is dominated by outdated coal-fired power plants, efforts to minimize the environmental impact are associated with high costs. Therefore, optimal paths for the development of the energy sector should be sought in order to achieve ambitious long-term strategic goals, while minimizing the negative impact on the consumers’ home...
-
Assessment of the Current Potential of Hydropower for Water Damming in Poland in the Context of Energy Transformation
PublikacjaThe present paper indicates that hydropower, including small hydropower plants (SHPs), may play a very important role in Poland’s energy transformation in the near future. The development of SHPs may also increase water resources in the steppe Poland. Additionally, the aim of the present research is to conduct the PEST analysis of SHPs in Poland, taking into account the SHP potential. For the first time, maps showing the power...
-
Ultrasonic diagnostics of concrete T-beams used in bridge structures
PublikacjaThis paper describes a method of ultrasonic diagnostics used for prefabricated concrete elements. The studies are focused on the applicability of nondestructive techniques based on impulse and wave packet induced elastic waves for the condition assessment of T-shaped bridge beams. Experimental tests were performed for the prestressed beam used for the superstructure of the viaduct on A1 highway near Toruń. In addition numerical...
-
ADAPTIVE IDENTIFICATION OF TIME-VARYING IMPULSE RESPONSE OF UNDERWATER ACOUSTIC COMMUNICATION CHANNEL
PublikacjaThe transmission properties of underwater acoustic communication channel can change dynamically due to the movement of acoustic system transmitter and receiver or underwater objects reflecting transmitted signal. The time-varying impulse response measurement and estimation are necessary to match the physical layer of data transmission to instantaneous channel propagation conditions. Using the correlative measurement method, impulse...
-
Detection of damages in a rivetted plate
PublikacjaThe paper presents the results of damage detection in a riveted aluminium plate. The detection method has been based on Lamb wave propagation. The plate has been analysed numerically and experimentally. Numerical calculations have been carried out by the use of the time-domain spectral finite element method, while for the experimental analysis laser scanning Doppler vibrometry (LSDV) has been utilised. The panel has been excited...
-
Multipath routing for quality of service differentiation and network capacity optimization in broadband low-earth orbit systems
PublikacjaThis paper shows the importance of employing multiple different paths for routing in Inter-Satellite Link (ISL) networks in broadband Low-Earth Orbit (LEO) satellite systems. A theoretical analysis is presented and a routing concept is proposed to demonstrate three facts that make multipath routing especially important in broadband LEO networks: (1) differences in the propagation delays have a much greater impact on end-to-end...
-
An Empirical Model for the Polarisation Characteristics of Indoor Off-Body Channels
PublikacjaThis paper presents an analysis of the polarisation characteristics for the channel in dynamic off-body communications, and an empirical channel model, based on measurements performed at 2.45 GHz in an office environment. Body presence and propagation conditions have a strong influence on signal depolarisation. The model assumes three components for the total path loss: mean path loss, represented by a log-distance function with...
-
LSTM-based method for LOS/NLOS identification in an indoor environment
PublikacjaDue to the multipath propagation, harsh indoor environment significantly impacts transmitted signals which may adversely affect the quality of the radiocommunication services, with focus on the real-time ones. This negative effect may be significantly reduced (e.g. resources management and allocation) or compensated (e.g. correction of position estimation in radiolocalisation) by the LOS/NLOS identification algorithm. This paper...
-
Detection of debonding in reinforced concrete beams using ultrasonic transmission tomography and hybrid ray tracing technique
PublikacjaThis paper concerns inspection of reinforced concrete elements, with particular emphasis on assessing the quality of the adhesive connection between steel and concrete. A novel theoretical model was developed to determine the paths of transmitted, refracted and reflected elastic waves as well as a creeping wave propagated along the inclusion surface. Imaging the internal structure of tested beams was based on wave propagation measurements...
-
Macrophytobenthos in the Puck Bay in 2010–2018 Dataset
PublikacjaThe dataset titled Biomass of macrophytobenthos in the Puck Bay in 2010-2018 con-tains data on the qualitative composition and biomass of macrophytobenthos (flow-er plants and macroalgae) in samples collected in the Puck Bay area (Gulf of Gdańsk, southern Baltic Sea) at 20 stations between 2010–2018. The data was supplemented with additional information: values of measured parameters of water and sediment, e.g. tem-perature...
-
A reliable synthesis of discrete-time H-inf control. Part I: basic theorems and J-lossless conjugators
PublikacjaThe paper gives a basis for solving many problems of numerically reliable synthesis of sub-optimal discrete-time control in H-inf. The approach is based on J-lossless factorisation of the delta-domain chain-scattering description of continuous-time plants being controlled. Relevant properties of poles and zeroes of chain-scattering models are given. Necessary and sufficient conditions for the existence of stabilising J-lossless...
-
The Impact of Micro-Sources on Voltage Distortions in a Power Grid
PublikacjaThe increase in the number of photovoltaic (PV) systems integrated with low voltage (LV) grids has led to a great need to analyse the impact of these systems on the quality of electricity and the reliability of its supply. This paper presents and compares the energy quality requirements imposed by various countries on photovoltaic plants. Then, based on real object tests and simulation in DIgSILENT PowerFactory, the impact has...
-
Metody redukcji zróżnicowania materiałów wejściowych w warunkach wysokiej różnorodności produktów gotowych
PublikacjaArtykuł opisuje zagadnienie związane z negatywnym wpływem wysokiego zróżnicowania materiałów wejściowych w procesach produkcyjnych o wysokiej różnorodności produktów gotowych. W pierwszej części pracy opisane zostało oddziaływanie zróżnicowania materiału na podstawowe mierniki skuteczności procesu produkcyjnego z uwzględnieniem cen zakupu materiałów, kosztów utrzymania zapasów, jakości produktu oraz wydajności maszyn i urządzeń....
-
NUMERYCZNY MODEL OBLICZENIOWY OBIEGU TURBINY KLASY 300 MW
PublikacjaNiniejszy artykuł stanowi opis modelu obiegu cieplnego turbiny o mocy 360MW, utworzonego w preprocesorze numerycznego programu obliczeniowego onazwie DIAGAR. Zadaniem opisywanego modelu jest odtwarzanie zjawisk fizycznych zachodzących w poszczególnych urządzeniach składowych obiegu, zarówno podczas poprawnej (sprawnej) pracy bloku energetycznego, jak i w przypadku pojawienia się niesprawności. Utworzony...
-
Process engineering in circular economy 22/23
Kursy OnlineBackground of the circular economy What is the circular economy? (Definition) How is the circular economy different from a linear economy? How do materials circulate in the circular economy? The circular economy and sustainable development How to measure circularity? Link between the circular economy and life cycle assessment (LCA) What are the benefits of the circular economy? The circular economy policies and governance Wastewater...
-
Developing assumptions for the tram noise attenuation passive system using the noise maps analysis method
PublikacjaThe paper presents experimental research carried out to determine the possible actions to reduce thenoise generated by trams in a highly urbanised area. A few design strategies affecting tram ride qualityhave been presented – especially in the aspect of the acoustic phenomena. Main sources of the noisein trams were characterised. The paper includes selected results of comprehensive...
-
Microcrack monitoring and fracture evolution of polyolefin and steel fibre concrete beams using integrated acoustic emission and digital image correlation techniques
PublikacjaThe use of polymer and steel fibres in plain concrete appears to be an excellent solution for limiting crack propagation and improving the post-ductility performance of concrete structures. Based on this premise, this study investigated the fracture evolution of polyolefin fibre-reinforced concrete (PFRC) and steel fibre-reinforced concrete (SFRC) specimens through the integrated application of two diagnostic techniques, acoustic...
-
Spectral Finite Element Method in Condition Monitoring and Damage Detection
PublikacjaIt is well known that the dynamic behaviour of engineering structures may carry very important and crucial information that can be further used for the assessment of their condition as well as detection of any damage induced. The current interest in monitoring techniques based on the propagation of guided elastic waves requires that numerical techniques used for modelling the phenomena associated must shift into the realm of high...
-
Twenty years' (1996-2016) tropospheric parameters for selected EPN stations derived from GPS double-difference processing
Dane BadawczePropagation of global navigation satellite systems (GNSS) signals through the Earth’s atmosphere is affected by its physical properties. Both hydrostatic and wet part of the atmosphere (mostly related with troposphere) causes delays of GNSS signal, which usually are expressed in the zenith direction (zenith hydrostatic delay - ZHD, and zenith wet delay...
-
Twenty years' (1996-2016) tropospheric parameters for selected EPN stations derived from GPS precise point positioning
Dane BadawczePropagation of global navigation satellite systems (GNSS) signals through the Earth’s atmosphere is affected by its physical properties. Both hydrostatic and wet part of the atmosphere (mostly related with troposphere) causes delays of GNSS signal, which usually are expressed in the zenith direction (zenith hydrostatic delay - ZHD, and zenith wet delay...
-
Analysis and design of a polarizer rotator system
PublikacjaW artykule przedstawiono metodę analizy wielosekcyjnego polaryzatora złożonego z periodycznych szyków obiektów cylindrycznych. W celu analizy badanej struktury zastosowano metodę pełnofalową opartą na metodzie dopasowania rodzajów. Opracowany algorytm został zweryfikowany poprzez porównanie uzyskanych wyników z wynikami otrzymanymi z przybliżonego modelu transmisyjnego oraz z własnymi pomiarami wykonanego prototypu.
-
Analysis of scattering from arbitrary configuration of elliptical obstacles using T-matrix representation
PublikacjaW artykule przedstawiono nową metodę analizy zjawiska rozpraszania dla dowolnej konfiguracji obiektów eliptycznych. Przedstawione podejście, dotyczącego pojedynczego obiektu, oparte jest na połączeniu analizy w układzie eliptycznym i cylindrycznym. W analizie wielu obiektów wykorzystana została procedura iteracyjna. Uzyskane wyniki zostały zweryfikowane przy wykorzystaniu oprogramowania komercyjnego.
-
A new hybrid method for analysis of scattering from arbitrary configuration of cylindrical objects
PublikacjaArtykuł opisuje nową hybrydową metodę analizy rozpraszania fali elektromagnetycznej od obiektów cylindrycznych o dowolnym przekroju poprzecznym. W prezentowanym podejściu każdy obiekt jest traktowany jako efektywny cylinder o przekroju kołowym, opisany przez macierz impedancyjną. W celu uzyskania owej macierzy zastosowano połączenie metod różnic skończonych w dziedzinie częstotliwości (FDFD) i dopasowania rodzajów (MM). W celu...
-
Resonance Frequency Calculation of a Multilayer and Multipatch Spherical Microstrip Structure Using a Hybrid Technique
PublikacjaThis communication offers a rigorous analysis of the resonance frequency problem of a spherical microstrip structure mounted on a multilayer, dielectric-coated metallic sphere, with an electrically small radius. The structure consists of single or multiple metallic patches with arbitrary shapes. A full-wave analysis is employed with the use of proposed hybrid approach, combining the finite-difference technique with a spectral domain...
-
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...
-
A Wideband Rotary-Joint-Free H-Plane Horn Antenna With 360° Steerable Radiation Pattern Using Gap Waveguide Technology
PublikacjaConsidering the limitations of electronically steerable antennas such as limited steering span, gain degradation for large steering angles, complexity, and cost, this article is focused on the design of a simple mechanically steerable H-plane horn antenna. It is shown that since there is no need for an electrical connection between the top and bottom sections of a gap waveguide (GWG), if a sectoral horn is properly designed and realized...
-
Efficient Simulation-Based Global Antenna Optimization Using Characteristic Point Method and Nature-Inspired Metaheuristics
PublikacjaAntenna structures are designed nowadays to fulfil rigorous demands, including multi-band operation, where the center frequencies need to be precisely allocated at the assumed targets while improving other features, such as impedance matching. Achieving this requires simultaneous optimization of antenna geometry parameters. When considering multimodal problems or if a reasonable initial design is not at hand, one needs to rely...
-
A Low-Profile Metal-backed Dipole Loaded with Closely Coupled Arc-shaped Open Stubs for On-metal Tag Design with Wide Frequency Tuning Capability
PublikacjaThis research has presented a single-layer metal-backed dipole antenna, which consists of a feedline loaded with two pairs of closely-coupled arc-shaped open stubs, for designing a metal-mountable tag that features tuning capability over a wide range of frequency. Here, the stubs can generate sufficient inductive reactance for bringing down the tag resonant frequency tunable in both the regulated UHF RFID passbands (North American...
-
Accelerated Parameter Tuning of Antenna Structures by Means of Response Features and Principal Directions
PublikacjaPopularity of numerical optimization has been steadily on the rise in the design of modern antenna systems. Resorting to mathematically rigorous parameter tuning methods is a matter of practical necessity as interactive techniques (e.g., parameter sweeping) are no longer adequate when handling several performance figures over multi-dimensional parameter spaces. The most common design scenarios involve local tuning since decent...
-
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...
-
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...
-
Coplanar Waveguide-Fed Broadband Microwave Devices with (or without) a Thin Dielectric Substrate for Use in Flexible Electronic Systems
PublikacjaTwo examples of microwave devices, fed by a coplanar waveguide and realized on a thin substrate (or without such a substrate), are employed to investigate the influence of devices’ curvatures and the proximity of different materials on their parameters. To perform the tests, a broadband antenna and a low-pass filter are chosen. A feeding coplanar waveguide is realized on a dielectric material brick attached to an SMA connector...
-
Simulation-Driven Design of Microstrip Antenna Subarrays
PublikacjaA methodology for computationally efficient simulation-driven design of microstrip antenna subarrays is presented. Our approach takes into account the effect of the feed (e.g., a corporate network) on the subarray side lobe level and allows adjusting both radiation and reflection responses of the structure under design within a single automated process. This process is realized as surrogate-based optimization that produces designs...
-
An Analysis of Probe-Fed Rectangular Patch Antennas With Multilayer and Multipatch Configurations on Cylindrical Surfaces
PublikacjaA multi-patch configuration of probe-fed rectangular microstrip antennas mounted on a cylindrical body, with electrically small radius, with an arbitrary number of substrate and superstrate layers is investigated in this paper. A full-wave analysis and a moment-method calculation are employed. A unified procedure for creating proper matrices for the investigated geometry of the structure is outlined here. Numerical results for...
-
Efficient Multi-Objective Simulation-Driven Antenna Design Using Co-Kriging
PublikacjaA methodology for fast multi-objective antenna optimization is presented. Our approach is based on response surface approximation (RSA) modeling and variable-fidelity electromagnetic (EM) simulations. In the design process, a computationally cheap RSA surrogate model constructed from sampled coarse-discretization EM antenna simulations is optimized using a multi-objective evolutionary algorithm. The initially determined Pareto...
-
Periodicity Matters: Grating or lattice resonances in the scattering by sparse arrays of subwavelength strips and wires.
Publikacja -
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...
-
Development of a compact microstrip resonant cell aimed at efficient microwave component size reduction
PublikacjaA comprehensive comparison of a wide collection of compact microstrip resonant cells (CMRCs) found in the extensive body of literature has been presented. The evaluation of different CMRC designs has led to the selection of the most promising CMRC geometry for the efficient miniaturisation of modern microwave components. In order to showcase the vital effectiveness of the approach, the initially selected CMRC has been notably...
-
A new approach to a fast and accurate design of microwave circuits with complex topologies
PublikacjaA robust simulation-driven design methodology of microwave circuits with complex topologies has been presented. The general method elaborated is suitable for a wide class of N-port unconventional microwave circuits constructed as a deviation from classic design solutions. The key idea of the approach proposed lies in an iterative redesign of a conventional circuit by a sequential modification and optimisation of its atomic building...
-
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...
-
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...
-
Triangulation-based Constrained Surrogate Modeling of Antennas
PublikacjaDesign of contemporary antenna structures is heavily based on full-wave electromagnetic (EM) simulation tools. They provide accuracy but are CPU-intensive. Reduction of EM-driven design procedure cost can be achieved by using fast replacement models (surrogates). Unfortunately, standard modeling techniques are unable to ensure sufficient predictive power for real-world antenna structures (multiple parameters, wide parameter ranges,...
-
On Alternative Approaches to Design of Corporate Feeds for Low-Sidelobe Microstrip Linear Arrays
PublikacjaTwo design approaches, illustrated by simulations and measurements, aiming at a systematic computer-aided design of printed circuit feeds for low-sidelobe microstrip antenna arrays are described. The novelty of these approaches resides in identification of the optimal feed architectures with subsequent simulation-based optimization of the feed and array aperture dimensions. In this work, we consider microstrip corporate feeds realizing...
-
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...
-
Low-fidelity model considerations for simulation-based optimisation of miniaturised wideband antennas
PublikacjaHere, variable-fidelity electromagnetic (EM)-based design optimisation of miniaturised antennas is discussed. The authors focus on an appropriate selection of discretisation density of the low-fidelity EM model, which results in good performance of the optimisation algorithm in terms of its computational complexity and reliability. Trust-region gradient search with low-fidelity model corrected by means of non-linear frequency scaling...
-
Domain segmentation for low-cost surrogate-assisted multi-objective design optimisation of antennas
PublikacjaAbstract: Information regarding the best possible design trade-offs of an antenna structure can be obtained through multiobjective optimisation (MO). Unfortunately, MO is extremely challenging if full-wave electromagnetic (EM) simulation models are used for performance evaluation. Yet, for the majority of contemporary antennas, EM analysis is the only tool that ensures reliability. This study introduces a procedure for accelerated...
-
Simulation-driven size-reduction-oriented design of multi-band antennas by means of response features
PublikacjaThis study addresses the problem of explicit size reduction of multi-band antennas by means of simulation-driven optimisation. The principal difficulty of electromagnetic (EM)-based miniaturisation of multi-band antennas is that several resonances have to be controlled independently (both in terms of their frequency allocation and depth) while attempting to reduce physical dimensions of the structure at hand. The design method...
-
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...