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Dedicated scheduling of tasks to minimize mean flow time
PublikacjaThis paper investigates the complexity of scheduling biprocessor tasks on dedicated processors to minimize mean flow time. Since the general problem is strongly NP-hard, we assume some restrictions on task lengths and the structure of associated scheduling graphs. Of particular interest are acyclic graphs. In this way we identify a borderline between NP-hard and polynomially solvable special cases.
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Modeling of flow phenomena associated with polymer injection into a mold
PublikacjaPodczas wtrysku tworzywa do formy w strefie tworzywo-ścianka formy występują zjawiska, które są źródłem zwiększonej chropowatości powierzchni i wad wypraski. W pracy pisano powyższe zjawiska oraz zaprezentowano model numeryczny, umożliwiający symulację tych zjawisk. Symulację komputerową wykonano w CI TASK stosując program FIDAP. Wyniki badań symulacyjnych zweryfikowano badaniami doświadczalnymi, wykonując fotografie i profilogramy...
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Modeling of entrained flow steam gasification of sewage sludge
PublikacjaProper management of sewage sludge becomes increasingly problematic due to legal requirements aiming at diminishing environmental impact, as well as rationalizing the utilization from the point of view of logistics. Steam gasification of sewage sludge can result in very good quality of the producer gas. So far, the works have been focused on the gasification in fixed bed gasifiers. However, this does not allow to take full advantage...
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Rational determination of dynamic characteristics of fluid-flow Reactors
PublikacjaPodstawowa charakterystykę reaktorów stanowi krzywa rozkładu czasu zatrzymania. Jej dokładne wyznaczenie jest trudne i kosztowne. W pracy zaproponowano wykorzystanie metody aproksymacyjnej, polegającej na zastąpieniu rzeczywistej funkcji przez jej przebieg uproszczony. Zaproponowano aproksymację rozkładem trójkątnym. Na konkretnym przykładzie pokazano, że metoda ta daje lepsze wyniki niż powszechnie stosowany model przepływu tłokowego.
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Steady magnetohydrodynamic flow in a diverging channel with suction or blowing
PublikacjaAn analysis is made of steady two-dimensional divergent flow of an electrically conducting incompressible viscous fluid in a channel formed by two non-parallel walls, the flow being caused by a source of fluid volume at the intersection of the walls. The fluid is permeated by a magnetic field produced by an electric current along the line of intersection of the channel walls. The walls are porous and subjected to either suction...
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Modeling lubricant flow between thrust-bearing pads
PublikacjaInlet temperature is one of the main inputs in all models for the analysis of fluid film bearing performance. At the same time, inlettemperature distribution and also oil velocity distribution at the inlet are the result of flow phenomena in the gap between the bearingpads. These phenomena are complex and in many cases further affected by any special arrangements of forced oil supply to the gapbetween pads. The reason for such...
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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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Educational Dataset of Handheld Doppler Blood Flow Recordings
PublikacjaVital signals registration plays a significant role in biomedical engineering and education process. Well acquired data allow future engineers to observe certain physical phenomena as well learn how to correctly process and interpret the data. This dataset was designed for students to learn about Doppler phenomena and to demonstrate correctly and incorrectly acquired signals as well as the basic methods of signal processing. This...
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Inverse Flood Routing Using Simplified Flow Equations
PublikacjaThe paper considers the problem of inverse flood routing in reservoir operation strategy. The aim of the work is to investigate the possibility of determining the hydrograph at the upstream end based on the hydrograph required at the downstream end using simplified open channel flow models. To accomplish this, the linear kinematic wave equation, the diffusive wave equation and the linear Muskingum equation are considered. To achieve...
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CFD analysis of fluid flow through the labyrinth seal
PublikacjaSteam and gas turbines are some of the fundamental means of power generation. The energy efficiency of the turbines, however, is not satisfactory. Ever since the start-up of the first turbine in the world, engineers have been striving for their increased efficiency. Multiple solutions to the problem of steam loss in an operating turbine are available. The use of seals is one of them. Empirical methods or numerical calculations...
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Analysis of the radiation dose in UV-disinfection flow reactors.
PublikacjaTheoretical considerations devoted to the variation of UV radiation doses in flow disinfection reactors are presented. The minimal time required by the fluid to pass the reactor was determined and combined with the radiation intensity. The active zones of the reactor were determined.
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Flow maldistribution and its mitigation in mini heat exchangers
PublikacjaIn the present paper, a detailed numerical investigation has been carried out to analyze the flow maldistribution in 50 parallel 1 mm x 1 mm rectangular minichannels and 1 mm depth minigap section with rectangular, trapezoidal, triangular or concave mani-folds in Z-type flow configuration (16 different cases). The working medium was ethanol and the mass flow rate was 5×10-4 kg/s. Both sections was heated from the bottom side. Heat...
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NUMERICAL SIMULATIONS OF GAP FLOW ABOVE ROTATING DISK
PublikacjaA rotating disk can be considered a basic configuration for the investigati ons of the impact of various conditions on the flow through the clearance between the s hrouded turbine blade and the casing. Numerical calculations using Fine/Turbo Numeca were conducted to examine the influence of the rotational velocity and the pressure differ ence across the disk on the flow conditions, especially the mass flow through the clearance....
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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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Experimental study on the seepage flow through the ice jam
PublikacjaIn light of the observed climate change, there is a need for better understanding of river ice processes for managing water resources in the cold regions. Ice jams produce significant resistance which may cause rise of water level and flooding. The jam resistance is only referred to the roughness of its underside, and this approach lead to exceptional roughness coefficients which has no physical explanation. Number of evidences...
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Analytical Steady-State Model of the Pipeline Flow Process
PublikacjaThe paper addresses the issue of modeling the flow process in transmission pipelines. A base model used for numerical simulation is introduced. Under certain assumptions concerning steady state analysis, the differential equations describing the process are solved analytically for two cases: zero and nonzero inclination angle α. These equations describe a constant flow rate and a corresponding distribution of the pressure along...
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Discrete-continuous optimisation of an axial flow blood pump
PublikacjaThis paper presents results of discrete-continuous optimisation of an axial flow blood pump. Evolution Strategies (ES) are used as a global optimisation method in order to localise the optimal solution in relatively short time. The whole optimisation process is fully automated. This also applies to geometry modelling. Numerical simulations of the flow inside the pump is performed by means of the Reynolds-Average Navier-Stokes...
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River flow simulation based on the HEC-RAS system
PublikacjaThis work considers the problem of river floods, and presents a computer solution that can be used to predict such a threat. The basic tool, called Hydrologic Engineering Centers for River Analysis System (HEC-RAS), and created by the US Army Corps of Engineering, is well developed; and the models created in the system HEC-RAS are quite realistic. For the purpose of solving practical national flood problems, simplified static and...
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River Flow Simulation Based on the HEC-RAS System
PublikacjaThis work considers the problem of river floods, and presents a computer solution that can be used to predict such a threat. The basic tool, called Hydrologic Engineering Centers for River Analysis System (HEC-RAS), and created by the US Army Corps of Engineering, is well developed; and the models created in the system HEC-RAS are quite realistic. For the purpose of solving practical national flood problems, simplified static and...
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A Concept of Freight Traffic Flow Regulations in the City of Gdansk
PublikacjaThis paper presents a review of state-of-art efforts in urban freight transport modelling in the context of their requirements and applicability as a basis for evaluation of city's freight transport policy. Freight transport mirrors all aspects of the city's economic activity and for that reason its proper planning is of extreme importance. However, urban freight system may be considered as the most varied and fragmented element...
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Free-surface elevation in open vortex flow controls
PublikacjaRotational form of fluid motion is complex, but very important in science and technology. The paper is devoted to the hydraulic mechanism of flow in open vortex flow controls, or regulators. The velocity field was described by the kinematic model, and intensity of rotation - by means of the energy balance between the input and dissipation. In consequence some algebraic expresions were obtained, which can be useful in approximated...
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MODEL FOR MEASUREMENT OF FLOW INSTALLATION TIME IN SDN SWITCH
PublikacjaSDN is the approach in telecommunication networks that separates control plane from data forwarding plane by specifying a single network entity as a controller that defines rules (called flows) of traffic forwarding for the switches connected to it. The time that is required for installation of these rules might be a hindrance for the overall performance of SDN network. In the paper, a model for testing and evaluating the influence...
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Graphene field-effect transistor application for flow sensing
PublikacjaMicroflow sensors offer great potential for applications in microfluidics and lab-on-a-chip systems. However, thermal-based sensors, which are commonly used in modern flow sensing technology, are mainly made of materials with positive temperature coefficients (PTC) and suffer from a self-heating effect and slow response time. Therefore, the design of novel devices and careful selection of materials are required to improve the overall...
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Acoustic heating produced in the thermoviscous flow of a Bingham plastic
PublikacjaThis study is devoted to the instantaneous acoustic heating of a Bingham plastic. The model of the Bingham plastic's viscous stress tensor includes the yield stress along with the shear viscosity, which differentiates a Bingham plastic from a viscous Newtonian fluid. A special linear combination of the conservation equations in differential form makes it possible to reduce all acoustic terms in the linear part of of the final equation...
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Silo music - mechanism of dynamic flow and structure interaction
PublikacjaArtykuł omawia zjawisko muzyki silosowej. Wykonano pomiary dynamiczne przyspieszeń, częstotliwości i postaci drgań własnych. Zaproponowano nowa hipotezę powstawania efektów dynamicznych podczas przepływu silosowego.
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Reduction of dynamic effects during granular flow in silos
PublikacjaOmówiono kilka efektywnych sposobów redukcji nadmiernych dynamicznych efektów występujących w przepływie silosowym w silosach modelowych. Sposoby te mogą być wykorzystane w praktyce silosowej.
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Silo music - mechanism of dynamic flow and structure interaction
PublikacjaArtykuł omawia zjawisko muzyki silosowe. Wykonano pomiary dynamiczne przyspieszeń, częstotliwości i postaci drgań własnych. Zaproponowano nowa hipotezę powstawania efektów dynamicznych podczas przepływu silosowego.
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Confined granular flow in silos : experiments and numerical investigation
PublikacjaW monografii opisano niektóre charakterystyczne zjawiska mające miejsce podczas przepływów silosowych materiałów sypkich. Wykonano badania doświadczalne oraz obliczenia numeryczne celem wyjaśnienia zjawisk. Doświadczenia wykonano w dużych i małych silosach. Obliczenia wykonano przy zastosowaniu metody elementów skończonych opartej na hipoplastycznym modelu konstytutywnym dla materiałów sypkich.
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Dynamic and tomography analysis of granular flow in cylindrical shell
PublikacjaW pracy przedstawiono wyniki badań ekperymentalnych dotyczących efektów dynamicznych występujących podczas przepływu materiałów sypkich w silosie cylindrycznym.
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Application of a cellular automaton to simulations of granular flow in silos
PublikacjaA cellular automaton based on a gas model of hydrodynamics was used to calculate the kinematics of non-cohesive granular materials during confined flow in a mass flow and funnel flow model silo. In the model, collisions of particles were taken into account during granular flow. In addition, a simplified automaton was used wherein granular flow was assumed as an upward propagation of holes through a lattice composed of cells representing...
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OVERLAP BETWEEN PERSONAL AND GROUP IDENTITY AND ITS RELATION WITH RADICAL PRO-GROUP ATTITUDES: DATA FROM A CENTRAL EUROPEAN CULTURAL CONTEXT
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Monitoring of solid behaviour during gravitational flow in rectangular silo
PublikacjaW pracy przedstawiono wyniki pomiarów zmian koncentracji w protokątnym modelu silosu. Omówiono przyczyny błędów pomiarowych w modelu protkątnym, zarówno dla danych surowych, jak rózniez danych zrekonstruowanych.
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NP-hardness of compact scheduling in simplified open and flow shops
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Power flow in typical series-parallel hybrid filters topologies
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Numerical Analysis of Flow in Building Arrangement: Computational Domain Discretization
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Modelling of energy flow in mechatronic systems. A bond graph approach
PublikacjaW referacie przedstawiono w sposób jednoliy modelowanie systemów mechatroniki metodą grafów wiązań (GW) w aspekcie symulacji przepływu energii. Omówiono ogólne założenia modelowania w ujęciu GW. Modelowanie przepływu energii rozważano na przykładzie napędu pojazdu hybrydowego PH-MAK.
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Determination of selected parameters in a 1D open channel flow model
PublikacjaOkreślenie parametrów jest ważnym etapem tworzenia modelu matematycznego. W przypadku jednowymiarowego modelu przepływu ze swobodną powierzchnią opisanego układem równań de Saint-Venanta, jedną z grup parametrów wymagających identyfikacji są parametry związane z tarciem. Mogą one być określone w różny sposób, ale w większości przypadków problem ten stanowi zagadnienie żle postawione. W takich przypadkach najczęściej stosowaną...
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Laboratorial studies on the seepage impact in open-channel flow turbulence
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Analysis of Turbulent Flow Measurements in a Flume with Induced Upward Seepage
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Flow cytometry as an estimation tool for honey bee sperm viability
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Design and evaluation of a flow-to-frequency converter circuit with thermal feedback
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Numerical study of turbulent flow and heat transfer of nanofluids in pipes
PublikacjaIn this work, Nusselt number and friction factor are calculated numerically for turbulent pipe flow (6 000 < Re < 12 000) with constant heat flux boundary condition using nanofluids. The nanofluid is modelled with the single-phase approach and the simulation results are compared with experimental data of Vajjha et al. [1]. Ethylene glycol and water, 60:40 EG/W mass ratio, as base fluid and SiO2 nanoparticles are used as nanofluid...
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On various modelling approaches to real-time visualisation of blood flow
PublikacjaThis paper reviews various modelling approaches to real-time visualisation of blood flow. These include classic, macroscale approach based on the momentum conservation equation together with a proper constitutive equation. Moreover, modern micro- and mesoscale approaches, such as molecular dynamics and dissipative particle dynamics, are discussed. Advantages and disadvantages of the discussed methods are highlighted with particular...
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PROPERTIES OF ONE DIMENSIONAL OPEN-CHANNEL STEADY FLOW EQUATIONS
PublikacjaIn this paper properties of discrete forms of one dimensional steady gradually varied flow equations are discussed. Such forms of flow equations are obtained as a result of approximation of their differential forms, which is required to solve them numerically. For such purpose explicit or implicit numerical approximation schemes for ordinary differential equations can be applied. It turns out that dependently on the chosen approximation...
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Recent progress in experimental studies of electrohydrodynamic flow in electrostatic precipitators
PublikacjaMany experimental, theoretical and numerical works were devoted to the electrohydrodynamic (EHD) flow generated in electrostatic precipitators (EPSs). The generally accepted conclusion from these studies is that the EHD flow plays an important role in the particle collection in ESPs. However, despite of the recent fast progress in numerical simulation and experimental techniques used in the ESPs studies many problems related to...
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Analysis of latency between quotations and capital flow in capital markets.
PublikacjaThe aim of this paper is to prove that the derivative of the log of capital flow understood as price times volume advances the derivative of log of the price. A certain concept of signal processing using linear filtering has been proposed to conduct the research.
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Flow of liquid in flat gaps of the satellite motor working mechanism
PublikacjaThe article describes the methodology and results of investigations of the flow of oil and HFA-E emulsion in flat gaps of the working mechanism of a satellite motor. The flow of liquid in those gaps is turbulent and not fully developed. The article presents two methods of modelling this flow. Method I makes use of the Darcy-Weisbach formula, while Method II bases on the assumption that in the variable-length gaps the flow is turbulent...
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Analysis of radiometric signal in sedimentating suspension flow in open channel
PublikacjaThe article discusses issues related to the estimation of the sedimentating solid particles average flow velocity in an open channel using radiometric methods. Due to the composition of the compound, which formed water and diatomite, received data have a very weak signal to noise ratio. In the process analysis the known determining of the solid phase transportation time delay the classical cross-correlation function is the most...
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Numerical Simulation of Open Channel Flow between Bridge Piers
PublikacjaPrzedstawiono dwuwymiarowy model przepływu wody płytkiej, który wykorzystano do symulacji przepływu wody w kanale otwartym w rejonie przekroju mostowego. Równania przepływu rozwiązano metodą objętości skończonych. Wyniki symulacji ruchu wody pomiędzy filarami mostowymi porównano z pomiarami laboratoryjnymi przeprowadzonymi w Laboratorium Hydrauliki i Inżynierii Środowiska politechniki Gdańskiej. Zgodność uzyskanych wyników obliczeń...
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Liveness measurements using optical flow for biometric person authentication
PublikacjaAutomatyczne rozpoznawanie twarzy jest jedną z najpopularniejszych technik biometrycznych, jednak nawet najdokładniejsze algorytmy identyfikacji okażą się bezużyteczne, jeśli będzie można je oszukać, np. używając zdjęcia zamiast rzeczywistej osoby. Dlatego też odpowiedni pomiar żywotności jest niezwykle istotny. W pracy zaprezentowano metodę, która jest w stanie rozróżnić pomiędzy sekwencjami wideo pokazującymi żywe osoby oraz...