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Wyniki wyszukiwania dla: TWO-DIMENSIONAL MODELING OF FLOWS, BI-HARMONIC HELMHOLTZ EQUATION, HYDRODYNAMICS OF WATER FLOW
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Performance of the flat plate solar collector operated with water-Al2O3 nanofluid
PublikacjaThis paper shows the experimental results of the performance a flat plate solar collector with water-Al2O3 nanofluid as a working fluid. The weight fractions of nanoparticles were 0.1%, 0.2% and 0.4%. The volume flow rate of nanofluid varied from 60 l/h to 170 l/h. The results show that application of nanofluids instead of pure water resulted in higher efficiency of the tested flat plate solar collector for given range of thermal...
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ENTERPRISE ACTIVITIES MODELING BY BPMN NOTATION
PublikacjaDepending on the process behavior, available know-how and organizational goals, different techniques and tools can be used for business process modeling. We concentrate on e-commerce, and try to find the best marketing strategy for the sales process improvement. In the paper we present the multilayer approach to define enterprise scenarios. This allows us to collect the suitable knowledge necessary for enterprise analysis and improvement....
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Wideband Modeling of DC-DC Buck Converter with GaN Transistors
PublikacjaThe general wideband modeling method of the power converter is presented on the example of DC-DC buck converter with GaN High Electron Mobility Transistors (HEMT). The models of all basic and parasitic components are briefly described. The two methods of Printed Circuit Board (PCB) layout parameter extraction are presented. The results of simulation in Saber@Sketch simulation software and measurements are compared. Next, the model...
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Knowledge-based performance-driven modeling of antenna structures
PublikacjaThe importance of surrogate modeling techniques in the design of modern antenna systems has been continuously growing over the recent years. This phenomenon is a matter of practical necessity rather than simply a fashion. On the one hand, antenna design procedures rely on full-wave electromagnetic (EM) simulation tools. On the other hand, the computational costs incurred by repetitive EM analyses involved in solving common tasks...
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End-to-end packed delay distribution of flows using EF PHB.
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Research into flows in turbine blade seals. Part I: Research methods
PublikacjaOpisano numeryczną i doświadczalną metodę badania przepływu w uszczelnieniu nadbandażowym stopnia turbinowego. Badania numeryczne przeprowadzono programem Fluent, a badania doświadczalne wykonano na powietrznej turbinie modelowej. Zamieszczono przykładowe wyniki.
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Research into flows in turbine blade seals. Part II: Numerical analysis
PublikacjaPrzedstawiono wyniki badań numerycznych programem Fluent przepływów w uszczelnieniu nadbandażowym stopnia turbinowego. Badania wykonano przy zastosowaniu różnych typów siatek obliczeniowych, różnych rodzajów "zszywek" oraz różnych metod obliczeniowych (Mixing Plane, Sliding Mesh, Multiple ReferenceFrame).
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Effect of Flow Normalization in Micro-Pin-Finned Heat Sink: Numerical Study
PublikacjaThe micro-pin-fin heat sink (MPFHS) is widely employed for the heat transfer enhancement of microchannel heat sinks. In the current paper, the effect of flow normalization on the thermohydraulic performance of micro-pin-finned heat sinks is studied numerically. Two geometries of MPFHSs, the conventional design micro-pin-fin heat sink (CD-MPFHS) with a uniform-width micro pin fin and the proposed design micro-pin-fin heat sink (PD-MPFHS)...
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Pool Boiling of Water–Al2O3 and Water–Cu Nanofluids Outside Porous Coated Tubes
PublikacjaThis paper deals with pool boiling ofwater–Al2O3 and water–Cu nanofluids on porous coated, horizontal tubes. Commercially available stainless-steel tubes having 10 mm outside diameter and 0.6 mm wall thickness were used to fabricate a test heater. Aluminum porous coatings 0.15 mm thick with porosity of about 40% were produced by plasma spraying. A smooth tube served as a reference tube. The experiments were conducted under different...
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Analytical ‘Steady-State’-Based Derivation and Clarification of the Courant-Friedrichs-Lewy Condition for Pipe Flow
PublikacjaThis article addresses the problem of choosing the optimal discretization grid for emulating fluid flow through a pipeline. The aggregated basic flow model is linearized near the operating point obtained from the steady state analytic solution of the differential equations under consideration. Based on this model, the relationship between the Courant number (μ) and the stability margin is examined. The numerically set coefficient...
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Modeling Parallel Applications in the MERPSYS Environment
PublikacjaThe chapter presents how to model parallel computational applications for which simulation of execution in a large-scale parallel or distributed environment is performed within the MERPSYS environment. Specifically, it is shown what approaches can be adopted to model key paradigms often used for parallel applications: master-slave, geometric parallelism (single program multiple data), pipelined and divide-and-conquer applications....
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Electrohydrodynamic secondary flow and particle collection efficiency in spike-plate multi-electrode electrostatic precipitator
PublikacjaIn this work the results of electrohydrodynamic (EHD) secondary flow measurements in a spike-plate type electrostatic precipitator (ESP) are presented. In the investigated ESP two-sided and one-sided spike electrodes were used as a discharge electrodes. The results of 2D PIV measurements showed that flow pattern obtained for a different spike tips positions in respect to the primary flow direction significantly changing the flow...
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APPLICATION OF MAGNETIC NANOPARTICLES FOR WATER TREATMENT
PublikacjaIn this study magnetic nanoparticles were fabricated and used for water treatment. Nanoparticles were prepared in two ways. The first one involved NiZn ferrite nanoparticles synthesized by co-precipitation of metal cations with sodium hydroxide at high temperature. The second one featured maghemite nanoparticles was prepared by saltassisted solid-state reaction. Modification and functionalization of nanoparticles surface was investigated....
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Modeling the pH effects on nitrogen removal in the anammox-enriched granular sludge
PublikacjaThe aim of the study was to determine the pH effects on nitrogen removal in the anammox-enriched granular sludge. The experimental data were extracted from a 4L completely-mixed batch reactor with the granular sludge at different initial pH values (6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5) and constant temperature T=30℃. Simulations were run in GPS-X 6.4 using a comprehensive mechanistic model Mantis2. Two kinetic parameters, including...
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A Bi-Objective Portfolio Optimization with Conditional Value-at-Risk
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Machine learning applied to bi-heterocyclic drugs recognition
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Bi-criteria Data Reduction for Instance-Based Classification
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Synthesis and magnetic properties of (Ba,Bi)1.54Rh8O16 hollandite
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Pawlak's flow graph extensions for video surveillance systems
PublikacjaThe idea of the Pawlak's flow graphs is applicable to many problems in various fields related to decision algorithms or data mining. The flow graphs can be used also in the video surveillance systems. Especially in distributed multi-camera systems which are problematic to be handled by human operators because of their limited perception. In such systems automated video analysis needs to be implemented. Important part of this analysis...
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A simplified energy dissipation based model of heat transfer for subcooled flow boiling
PublikacjaIn the paper a model is presented based on energetic considerations for subcooled flow boiling heat transfer. The model is the extension of authors own model developed earlier for saturated flow boiling and condensation. In the former version of the model we used the heat transfer coefficient for the liquid single-phase as a reference level, due to the lack of the appropriate model for heat transfer coefficient for the subcooled...
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Numerical modeling of quantum dynamical processes
PublikacjaIn this dissertation I present a high-precision (15, 18 or 33 decimal places) C++ implementation of quantum dynamics time propagation algorithms for both time-independent and time-dependent Hamiltonian with an inhomogeneous source term. Moreover I present an extension of both algorithms for time propagation to handle arbitrary number of coupled electronic levels. I have performed a careful validation of these implementations comparing...
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Stability of borophene dispersion in water
Dane BadawczeThis dataset contains the results of the studies of stability of borophene dispersion in water (1 µg/µL) based on the measurements of absorbance of the solution using UV-VIS spectroscopy.
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Electrohydrodynamic Secondary Flow and Particle Collection Efficiency in a One-sided Spike-plate Type Electrostatic Precipitator
PublikacjaIn this work, results of electrohydrodynamic secondary flow and particle collection efficiency measurements in an electrostatic precipitator under positive and negative voltage polarity are presented. The electrostatic precipitator had two plate collecting electrodes and a single spike discharge electrode. The spike tips were only on one side of the discharge electrode, therefore called a one-sided spike electrode. The electrohydrodynamic...
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total number and biomass of bacteria in drinking water distribution systems.
PublikacjaIn the vast water supply network using traditional methods of treatment it is often impossible to maintain a constant and acceptable microbiological quality of water. In Poland the main reason of bacterial re-growth is presence of organic matter and nutrients in the circulating water and prolonged water retention in the network systems due to the decrease of water consumption, which has been observed for the last 20 years. In the...
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CFD Simulations and Tests of a Prototype Flow Control Valve
PublikacjaIn this paper a prototype of a flow control valve is described and numerically simulated. The flow control valve is used in hydraulic systems to maintain constant fluid flow despite changing loads of a receiver. The standard construction of this type of valves is modified mainly by eliminating the spring. The prototype consists the hydrostatically unloaded throttle valve and pressure ratio valve substituting pressure difference...
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Temperature-dependent structure-property modeling of viscosity for ionic liquids
PublikacjaIn this paper we present the methodology for assessing the ionic liquids' viscosity at six temperature points (25, 35, 45, 50, 60 and 70 [C]), which utilizes only the in silico approach. The main idea of such assessment is based on the "correction equation" describing the correlation between experimentally measured viscosity and theoretically derived density (calculated with use of molecular mechanics), given at 6 different temperature...
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Dimensional accuracy as the optimization criterion
PublikacjaW pracy zaproponowano nową formułę określania kosztów konstrukcji stalowej. Sformułowano nieliniowe zadanie optymalizacyjne minimalizacji kosztów koordynacyjnych wymiarów montażowych. Przedstawiono transformację problemu w zagadnienie dyskretne oraz zaproponowano rozwiązanie zadania metodami kombinatoryki.
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Superadditivity of two quantum information resources
PublikacjaEntanglement is one of the most puzzling features of quantum theory and a principal resource for quantum information processing. It is well known that in classical information theory, the addition of two classical information resources will not lead to any extra advantages. On the contrary, in quantum information, a spectacular phenomenon of the superadditivity of two quantum information resources emerges. It shows that quantum...
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Modeling and Designing Acoustical Conditions of the Interior – Case Study
PublikacjaThe primary aim of this research study was to model acoustic conditions of the Courtyard of the Gdańsk University of Technology Main Building, and then to design a sound reinforcement system for this interior. First, results of measurements of the parameters of the acoustic field are presented. Then, the comparison between measured and predicted values using the ODEON program is shown. Collected data indicate a long reverberation...
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Comparison of two novel in-syringe dispersive liquid–liquid microextraction techniques for the determination of iodide in water samples using spectrophotometry
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Probabilistic Assessment of Correlations of Water Levels in Polish Coastal Lakes with Sea Water Level with the Application of Archimedean Copulas
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The equivariant spectral flow and bifurcation of periodic solutions of Hamiltonian systems
PublikacjaWe define a spectral flow for paths of selfadjoint Fredholm operators that are equivariant under the orthogonal action of a compact Lie group as an element of the representation ring of the latter. This G-equivariant spectral flow shares all common properties of the integer valued classical spectral flow, and it can be non-trivial even if the classical spectral flow vanishes. Our main theorem uses the G-equivariant spectral flow...
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Comparison of heat transfer characteristics in surface cooling using microjets with water, ethanol and HFE7100 as test fluids
PublikacjaAccurate control of cooling parameters is required in ever wider range of technical applications. It is known that reducing the dimensions of the size of nozzle leads to an increase in the economy of cooling and improves its quality. Present study describes research related to the design and construction of the nozzles and microjet study, which may be applied in many technical applications such as in metallurgy, electronics, etc....
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Influence of nanoparticle concentration on convective heat transfer of water-Al2O3 nanofluids inside horizontal tubes
PublikacjaNanofluids came to be seen as a new generation of coolants, especially in single-phase systems. Conducted experiments indicate that the increase in thermal conductivity is not the only reason for the intensification of heat transfer when using nanofluids. Preliminary results of the experimental investigation of the forced convection heat transfer of water-Al2O3 nanofluids inside stainless steel tube with 8 mm internal diameter...
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Standing Waves in One-Dimensional Resonator Contaning an Ideal Isothermal Gas Affected by the Constant Mass Force
PublikacjaThe study is devoted to standing acoustic waves in one-dimensional planar resonator which containing an ideal gas. A gas is affected by the constant mass force. Two types of physically justified boundary conditions are considered: zero velocity or zero excess pressure at both boundaries. The variety of nodal and antinodal points is determined. The conclusion is that the nodes of pressure and antinodes of velocity do not longer...
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Robust Monitoring of Water Quality in Drinking Water Distribution System
PublikacjaThe paper develops a novel open loop set bounded observer for robust estimation of water quality in DWDS based on the advanced nonlinear quality dynamics model including disinfections by-products (DBPs). The observer utilises a cooperativeness of the quality dynamics model and is computationally efficient, hence applicable to on-line quality monitoring. The simulation results illustrate its good and sustainable performance.
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Simulations of freshwater lens recharge and salt/freshwater interfaces using the HYDRUS and SWI2 packages for MODFLOW
PublikacjaThe paper presents an evaluation of the combined use of the HYDRUS and SWI2 packages for MODFLOW as a potential tool for modeling recharge in coastal aquife rs subject to saltwater intrusion. The HYDRUS package for MODFLOW solves numerically the one-dimensional form of the Richards equation describing water flow in variably- saturated media. The code computes groundwater recharge to or...
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Video DATA - Traffic generation modeling for discount shops - Rakoczego Street
Dane BadawczeThe data includes video traffic data (vehicles, pedestrians, cyclists) registered at 21 Rakoczego street in Gdansk. The data covers the day 01.10.2020 at 6:00-10:00. The video camera was installed niearby the parking area belonging to the discount store Lidl. The data obtained was used in analysis, providing information about the modal split and the...
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Electrohydrodynamic Secondary Flow and Particle Collection Efficiency in Spike-Plate Multi-Electrode Electrostatic Precipitator
PublikacjaIn this work the results of electrohydrodynamic (EHD) secondary flowmeasurements in a spike-plate type electrostatic precipitator (ESP) are presented. In the investigated ESP two-sided and one-sided spike electrodes were used as a discharge electrodes. The results of 2D PIVmeasurements showed that flow pattern obtained for a different spike tips positions in respect to the primary flow direction significantly changing the flow...
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Fluid–solid interaction on a thin platelet with high-velocity flow: vibration modelling and experiment
PublikacjaThe paper concerns the nonlinear behaviour of a thin platelet that is streamlined in an aerodynamic tunnel. The air velocity in the aerodynamic tunnel was at 858.9 km/h or 0.7 Ma (Ma—Mach number is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound). This experiment was numerically simulated using FSI (fluid–solid interaction) tools, namely the coupling...
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Experimental investigation of forced convection of water-Al2O3 nanofluids inside horizontal tubes,
PublikacjaIn this paper, forced convection of water–Al2O3 nanofluids inside horizontal copper tube is studied experimentally. Experiments were conducted for three, i.e. 0.1%, 1% and 5% nanoparticle mass concentrations under transition and turbulent flow regimes. Average heat transfer coefficients and pressure drop values were determined and compared to distilled water. Enhancement of heat transfer for lower nanoparticle concentration and...
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Experimental study on the selected aspects of bow thruster generated flow field at ship zero-speed conditions
PublikacjaThe paper presents the results of experimental study on the interaction between the bow thrusters understood as the flow field changes generated by bow tunnel thruster in deep water conditions operated as a single and twin units. The research was limited to zero-speed case for the ship dead in the water. The influence of the hull form and jet spread between the neighbouring thrusters for several combinations of the applied bow...
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An optimised placement of the hard quality sensors for a robust monitoring of the chlorine concentration in drinking water distribution systems
PublikacjaThe problem of an optimised placement of the hard quality sensors in drinking water distribution systemsunder several water demand scenarios for a robust monitoring of the chlorine concentration is formulatedin this paper. The optimality is understood as achieving a desired trade off between the sensors and theirmaintenance costs and the accuracy of estimation of the chlorine concentration. The contribution of thiswork is a comprehensive...
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Modeling the application of steel slag in stabilizing expansive soil
PublikacjaThe objective of this study was to evaluate the suitability of steel slag as an additive to the engineering properties of weak clay soil. Different geotechnical laboratory tests were conducted on both stabilized and natural soils. Steel slag (SS) was added at a rate of 0, 5, 10, 15, 20, and 25% to the soil. Specific gravity, grain size analysis, Atterberg limit test, compaction test, free swell, California bearing ratio (CBR),...
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Providing Public Space Continuities in Post-Industrial Areas through Remodelling Land/Water Connections
PublikacjaThis article examines the problem of urban transformation strategies applied in recent years which are based on the creation of new water areas and modification of existing ones. The research is an attempt to prove that modifications of plans of water areas and forms of their borders may play an important role in achieving the best quality public spaces in post-industrial territories. The basis for demonstrating the importance...
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Modelling of Hydraulic Fracturing in Rocks in Non-isothermal Conditions Using Coupled DEM/CFD Approach with Two-Phase Fluid Flow Model
PublikacjaSkała łupkowa jest materiałem silnie niejednorodnym, nieciągłym i porowatym. W warunkach nieizotermicznych ruch płynu w układzie porów i kapilar jest silnie sprzężony z przenoszeniem ciepła. Przebieg szczeliny hydraulicznej silnie zależy od stopnia nasycenia skały. Opracowano innowacyjny model termo-hydro-mechaniczny oparty na modelu DEM w celu szczegółowego śledzenia frakcji ciecz/gaz w porach i pęknięciach pod kątem ich różnej...
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A CMRC-based compact rat-race coupler with harmonic suppression
PublikacjaIn this paper, an eective miniaturization technique exploiting compact microstrip resonant cells has been discussed and experimentally validated on the basis of a 3-dB microstrip rat-race coupler. The application of the method proposed has resulted in 91 % circuit area reduction in comparison to a conventional rat-race coupler. Experimental results show good agreement with theoretical characteristics, as well as an additional eect,...
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Low harmonic multipulse voltage converters using coupled reactors
PublikacjaThis paper presents a novel approach to the multi pulse voltage converters (VC), especially voltage source inverters (VSI) and matrix converters (MC) based on several typical identical modules connected in parallel using coupled reactors. Such arrangements resulting in lower voltage distortions at extremely low switching frequency. The proposed arrangement was validated by simulation. Laboratory models of 18- and 24pulse 3-level...
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Application of higher order spectra in harmonic analysis of corrosion process
PublikacjaZjawiska nieliniowe są niezwykle często spotykane w praktyce badań elektrochemicznych i korozyjnych. Typowym przykładem są procesy elektrodowe kontrolowane szybkością przeniesienia ładunku. Często stosowanym w takich przypadkach podejściem jest aproksymacja fragmentu krzywej prąd-napięcie za pomocą charakterystyki liniowej. W niniejszej pracy autorzy prezentują możliwość wykorzystania pomiarów składowych harmonicznych do oceny...
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Thresholds of Lasing as Solutions of Characteristic Equation for a VCSEL-type Layered Structure
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