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Wyniki wyszukiwania dla: multiequation models

Multiobjective 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 singleobjective 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...

Multilevel models of transport systems for traffic management
PublikacjaThe region of Pomorskie uses a variety of tools for forecasting and analysing transport. They can be operated, calibrated and updated with data that will be collected and stored in the TRISTAR system. An initiative of the Department of Highway Engineering of the Gdansk University of Technology is designed to develop and implement an integrated and hierarchical system for forecasting and analysing transport called MST (Multilevel...

Equivalent Single Layer Models in Free Vibration Analysis of Laminated MultiLayered Plates
PublikacjaThe performance of selected equivalent singlelayer (ESL) models is evaluated within several classical benchmark tests for small amplitude free vibration analysis of multilayered plates. The authors elaborated their own Finite Element software based on the firstorder shear deformation (FOSD) theory with some modifications incorporated including a correction of the transverse shear stiffness and an application of zigzag type functions....

Optimal shape design of multielement trawldoors using local surrogate models
PublikacjaTrawldoors have a large influence on the fuel consumption of fishing vessels. Design and optimization of trawldoors using computational models are a key factor in minimizing the fuel consumption. This paper presents an optimization algorithm for the shape design of trawldoor shapes using computational fluid dynamic (CFD) models. Accurate CFD models are computationally expensive. Therefore, the direct use of traditional optimization...

Fast MultiObjective Aerodynamic Optimization Using Sequential Domain Patching and Multifidelity Models
PublikacjaExploration of design tradeoffs for aerodynamic surfaces requires solving of multiobjective optimization (MOO) problems. The major bottleneck here is the timeconsuming evaluations of the computational fluid dynamics (CFD) model used to capture the nonlinear physics involved in designing aerodynamic surfaces. This, in conjunction with a large number of simulations necessary to yield a set of designs representing the best possible...

Variablefidelity CFD models and coKriging for expedited multiobjective aerodynamic design optimization
PublikacjaPurpose – Strategies for accelerated multiobjective optimization of aerodynamic surfaces are investigated, including the possibility of exploiting surrogate modeling techniques for computational fluid dynamic (CFD)driven design speedup of such surfaces. The purpose of this paper is to reduce the overall optimization time. Design/methodology/approach – An algorithmic framework is described that is composed of: a search space reduction,...

Fast MultiObjective Antenna Optimization Using Sequential Patching and VariableFidelity EM Models
PublikacjaIn this work, a technique for fast multiobjective design optimization of antenna structures is presented. In our approach, the initial approximation of the Pareto set representing the best possible tradeoffs between conflicting design objectives is obtained by means of sequential patching of the design space. The latter is a stencilbased search that aims at creating a path that connects the extreme Paretooptimal designs (obtained...

CostEfficient EMDriven Size Reduction of Antenna Structures by MultiFidelity Simulation Models
PublikacjaDesign of antenna systems for emerging application areas such as the Internet of Things (IoT), fifth generation wireless communications (5G), or remote sensing, is a challenging endeavor. In addition to meeting stringent performance specifications concerning electrical and field properties, the structure has to maintain small physical dimensions. The latter normally requires searching for tradeoff solutions because miniaturization...

Surface sliding in human abdominal wall numerical models: Comparison of singlesurface and multisurface composites
PublikacjaDetermining mechanical properties of abdominal soft tissues requires a coupled experimentalnumerical study, but first an appropriate numerical model needs to be built. Precise modeling of human abdominal wall mechanics is difficult because of its complicated multilayer composition and large variation between specimens. There are several approaches concerning simplification of numerical models, but it is unclear how far one could...

Rapid Design Centering of MultiBand Antennas Using KnowledgeBased Inverse Models and Response Features
PublikacjaAccounting for manufacturing tolerances as well as uncertainties concerning operating conditions and material parameters is one of the important yet often neglected aspects of antenna development. Appropriate quantification of uncertainties allows for estimating the fabrication yield but also to carry out robust design (e.g., yield maximization). For reliability reasons, statistical analysis should be executed at the accuracy level...

Fast MultiObjective Optimization of NarrowBand Antennas Using RSA Models and Design Space Reduction
PublikacjaComputationally efficient technique for multiobjective design optimization of narrowband antennas is presented. In our approach, the corrected lowfidelity antenna model (obtained through coarsediscretization EM simulations) is enhanced using frequency scaling and response correction, sampled, and utilized to obtain a fast response surface approximation (RSA) antenna surrogate. The RSA model is constructed in the reduced design space....

Initializing the EM Algorithm for Univariate Gaussian, MultiComponent, Heteroscedastic Mixture Models by Dynamic Programming Partitions
Publikacja 
MultiDBD plasma actuator for flow separation control around NACA 0012 and NACA 0015 airfoil models
PublikacjaIn this paper application of innovative multiDBD plasma actuator for flow separation control is presented. The influence of the airflowgenerated by this actuator on the flow around NACA 0012 and NACA 0015 airfoil models was investigated. The results obtained from 2D PIVmeasurements showed that the multiDBD actuator with floating interelectrode can be attractive for leading and trailing edge separation control.

COMPARATIVE ANALYSIS OF RESULTS OF APPLICATION OF MARKOV AND SEMIMARKOV PROCESSES TO RELIABILITY MODELS OF MULTISTATE TECHNICAL OBJECTS
PublikacjaDuring rational operation of technical objects and systems various operational decisions are made and decisionmaking process itself should be consisted in selecting that considered most favourable out of all possible to be taken. Choice of such decision is possible after taking into account many different information items but it never be completely correct without accounting for data and indices dealing with reliability. In...

Scalability of surrogateassisted multiobjective optimization of antenna structures exploiting variablefidelity electromagnetic simulation models
PublikacjaMultiobjective optimization of antenna structures is a challenging task due to highcomputational cost of evaluating the design objectives as well as large number of adjustable parameters. Design speedup can be achieved by means of surrogatebased optimization techniques. In particular, a combination of variablefidelity electromagnetic (EM) simulations, design space reduction techniques, response surface approximation (RSA) models,...

Rapid multiobjective optimization of antennas using nested kriging surrogates and singlefidelity EM simulation models
PublikacjaEver increasing performance requirements make the design of contemporary antenna systems a complex and multistage process. One of the challenges, pertinent to the emerging application areas but also some of the recent trends (miniaturization, demands for multifunctionality, etc.), is the necessity of handling several performance figures such as impedance matching, gain, or axial ratio, often over multiple frequency bands. The...

Rapid multiobjective antenna design using pointbypoint Pareto set identification and local surrogate models
PublikacjaAntenna design is inherently a multicriterial problem.Determination of the best possible tradeoffs between conflicting objectives (a socalled Pareto front), such as reflection response, gain, and antenna size, is indispensable from the designer’s point of view, yet challenging when highfidelity electromagnetic (EM) simulations are utilized for performance evaluation. Here, a novel and computationally...

Efficient Surrogate Modeling and Design Optimization of Compact Integrated OnChip Inductors Based on MultiFidelity EM Simulation Models
PublikacjaHighperformance and smallsize onchip inductors play a critical role in contemporary radiofrequency integrated circuits. This work presents a reliable surrogate modeling technique combining lowfidelity EM simulation models, response surface approximations based on kriging interpolation, and space mapping technology. The reported method is useful for the development of broadband and highly accurate datadriven models of integrated...

MODELLING OF TOXIC COMPOUNDS EMISSION IN MARINE DIESEL ENGINE DURING TRANSIENT STATES AT VARIABLE PRESSURE OF FUEL INJECTION
PublikacjaTransient states are an important part of the spectrum of engine loads, especially the traction engines. In the case of marine diesel engines, transient states are of particular importance in reducing the analysis of motion units for special areas and maneuvering in port, the participation of transient states in the load spectrum significantly increases, also, the emission of toxic compounds from this period increases proportionally....

CREATING A RANKING OF DIAGNOSTIC PARAMETERS FOR THE DYNAMIC PROCESS OF A MARINE COMBUSTION ENGINE IN THE ASPECT OF MULTICRITERIA EVALUATIONS
PublikacjaThe change of some of the engine’s structural parameters affects the change of toxic compound emission in exhaust gases. It mainly applies to the damage sustained by the charge exchange system as well as the fuel system and the engine supercharging system. These changes are definitely higher during dynamic states and the related transient states. As such, it is possible to speak of a diverse sensitivity of the diagnostic parameters...

Problems of modelling toxic compounds emitted by a marine internal combustion engine for the evaluation of its structure parameters
PublikacjaThe paper presents the possibility of using an analytical study of the engine exhaust ignition to evaluate the technical condition of the selected components. Software tools available for the analysis of experimental data commonly use multiple regression model that allows the study of the effects and iterations between model input quantities and one output variable. The use of multiequation models gives a lot of freedom in the...

Technical State Assessment of Charge Exchange System of SelfIgnition Engine, Based On the Exhaust Gas Composition Testing
PublikacjaThis paper presents possible use of results of exhaust gas composition testing of self  ignition engine for technical state assessment of its charge exchange system under assumption that there is strong correlation between considered structure parameters and output signals in the form of concentration of toxic compounds (ZT) as well as unambiguous character of their changes. Concentration of the analyzed ZT may be hence considered...

Problems of modelling toxic compounds emitted by a marine internal combustion engine in unsteady states
PublikacjaContemporary engine tests are performed based on the theory of experiment. The available versions of programmes used for analysing experimental data make frequent use of the multiple regression model, which enables examining effects and interactions between input model parameters and a single output variable. The use of multiequation models provides more freedom in analysing the measured results, as those models enable simultaneous...

A Fortran95 algorithm to solve the threedimensional Higgs boson equation in the de Sitter spacetime
Dane BadawczeA numerically efficient finitedifference technique for the solution of a fractional extension of the Higgs boson equation in the de Sitter spacetime is designed. The model under investigation is a multidimensional equation with Riesz fractional derivatives of orders in (0,1)U(1,2], which considers a generalized potential and a timedependent diffusion...

Adrian Bekasiewicz dr hab. inż.
OsobyAdrian Bekasiewicz received the MSc, PhD, and DSc degrees in electronic engineering from Gdansk University of Technology, Poland, in 2011, 2016, and 2020, respectively. In 2014, he joined Engineering Optimization & Modeling Center where he held a Research Associate and a Postdoctoral Fellow positions, respectively. Currently, he is an Associate Professor with Gdansk University of Technology, Poland. His research interests include...

THE IDENTIFICATION OF TOXIC COMPOUND EMISSION SENSITIVITY AS A DIAGNOSTIC PARAMETER DURING DYNAMIC PROCESSES OF THE MARINE ENGINE
PublikacjaChanging some parameters of the engine structure alters the emission of harmful components in the exhaust gas. This applies in particular to the damage of charge exchange system as well as fuel system and engine supercharger. These changes are much greater during the dynamic states and their accompanying transitional processes. The different sensitivity of diagnostic parameters to the same force, coming from the engine structure,...

Effective Gap Size Index for Determination of Optimum Separation Distance Preventing Pounding between Buildings during Earthquakes
PublikacjaSeismic excitations may lead to collisions between adjacent civil engineering structures causing major damage. In this paper, an effective equation for calculating the gap size index is proposed so as to provide the optimum separation distance preventing structural pounding during different earthquakes. Evaluation of the best prediction of the required separation distance between two adjacent buildings was carried out by using...

The effect of social media communication on consumer perceptions of brands
PublikacjaResearchers and brand managers have limited understanding of the effects social media communication has on how consumers perceive brands. We investigated 504 Facebook users in order to observe the impact of firmcreated and usergenerated (UG) social media communication on brand equity (BE), brand attitude (BA) and purchase intention (PI) by using a standardized online survey throughout Poland. To test the conceptual model, we...

Data obtained by computation for Xray focusing using oriented Gaussian beams
Dane BadawczeThe propagation of Xray waves through an optical system consisting of several Xray refractive lenses is considered. Gaussian beams are exact solutions of the paraxial equation. The Helmholtz equation describes the propagation of a monochromatic electromagnetic wave. Since the widths of the beams are much larger than the wavelength of Xrays, Gaussian...

Balance error generated by numerical diffusion in the solution of Muskingum equation
PublikacjaIn the paper the conservative properties of the lumped hydrological models with variable parameters are discussed. It is shown that in the case of the nonlinear Muskingum equation the mass balance is not satisfied. The study indicates that the mass balance errors are caused by the improper form of equation and by the numerical diffusion which is generated in the solution. It has been shown that the classical way of derivation...

A highaccuracy complexphase method of simulating Xray propagation through a multilens system
PublikacjaThe propagation of Xray waves through an optical system consisting of many Xray refractive lenses is considered. For solving the problem for an electromagnetic wave, a finitedifference method is applied. The error of simulation is analytically estimated and investigated. It was found that a very detailed difference grid is required for reliable and accurate calculations of the propagation of Xray waves through a multilens...

Thermal ablation modeling via bioheat equation
PublikacjaWe consider Pennes’ bioheat equation and discuss an implicit numerical scheme which has better stability properties than other approaches. Our discussion concerns Carthesian geometry problems, however it carries over to spherical geometry models and more complicated shapes.

Wiktoria Wojnicz dr hab. inż.
OsobyDSc in Mechanics (in the field of Biomechanics)  Lodz Univeristy of Technology, 2019 PhD in Mechanics (in the field of Biomechanics)  Lodz Univeristy of Technology, 2009 (with distinction) Lista publikacji (2009  ) Publikacje z listy MNiSW: Wojnicz W., Wittbrodt E., Analysis of muscles' behaviour. Part I. The computational model of muscle. Acta of Bioengineering and Biomechanics, Vol. 11, No.4, 2009, p. 1521 Wojnicz...

Existence and uniqueness of solutions for singlepopulation McKendrickvon Foerster models with renewal
PublikacjaWe study a McKendrickvon Foerster type equation with renewal. This model is represented by a single equation which describes one species which produces young individuals. The renewal condition is linear but takes into account some history of the population. This model addresses nonlocal interactions between individuals structured by age. The vast majority of sizestructured models are also treatable. Our model generalizes a number...

Combining Computational Fluid Dynamics with a Biokinetic Model for Predicting Ammonia and Phosphate Behavior in Aeration Tanks
PublikacjaThe aim of this study was to use computational fluid dynamics for predicting the behavior of reactive pollutants (ammonia and phosphate) in the aerobic zone of the bioreactor located at the Wschod wastewater treatment plant in Gdansk, Poland. The onedimensional advectiondispersion equation was combined with simple biokinetic models incorporating the Monodtype expressions as source terms for the two pollutants. The problem was...

Multistate multireference MøllerPlesset secondorder perturbation theory for molecular calculations
PublikacjaThis work presents multi‐state multi‐reference Møller–Plesset second‐order perturbation theory as a variant of multi‐reference perturbation theory to treat electron correlation in molecules. An effective Hamiltonian is constructed from the first‐order wave operator to treat several strongly interacting electronic states simultaneously. The wave operator is obtained by solving the generalized Bloch equation within the first‐order...

Dimensionally Consistent Nonlinear Muskingum Equation
PublikacjaAlthough the Muskingum equation was proposed nearly 75 years ago, it is still a subject of active research. Despite of its simple form, the real properties of this equation have not been comprehensively explained. This paper proposes a new interpretation of the linear McCarthy’s relation. This relation can be interpreted only together with the storage equation, whereas the Muskingum equation can be derived directly from the system...

Equivariant Morse equation
PublikacjaThe paper is concerned with the Morse equation for flows in a representation of a compact Lie group. As a consequence of this equation we give a relationship between the equivariant Conley index of an isolated invariant set of the flow given by x˙ = − ∇f(x) and the gradient equivariant degree of ∇f. Some multiplicity results are also presented.

Numerical Simulations of Seepage in Dikes Using unsaturated and TwoPhase Flow Models
PublikacjaModeling of water flow in variably saturated porous media, including flood dikes, is often based on the Richards equation, which neglects the flow of pore air, assuming that it remains at constant atmospheric pressure. However, there is also evidence that the air flow can be important, especially when the connectivity between the pore air and atmospheric air is lost. In such cases a full twophase airwater flow model should be...

Computational issues of solving the 1D steady gradually varied flow equation
PublikacjaIn this paper a problem of multiple solutions of steady gradually varied flow equation in the form of the ordinary differential energy equation is discussed from the viewpoint of its numerical solution. Using the Lipschitz theorem dealing with the uniqueness of solution of an initial value problem for the ordinary differential equation it was shown that the steady gradually varied flow equation can have more than one solution....

TIME AND FREQUENCYDOMAIN QUASI2D SMALLSIGNAL MOSFET MODELS
PublikacjaA novel approach to smallsignal MOSFET modeling is presented in this book. As a result, time and frequencydomain physicsbased quasi2D NQS fourterminal smallsignal MOSFET models are proposed. The timedomain model provides the background to a novel DIBLincluded quasi‑2D NQS fourterminal frequencydomain smallsignal MOSFET model. Parameters and electrical quantities of the frequencydomain model are described by explicit...

Comparative Study of Integer and NonInteger Order Models of Synchronous Generator
PublikacjaThis article presents a comparison between integer and noninteger order modelling of a synchronous generator, in the frequency domain as well as in the time domain. The classical integer order model was compared to one containing half order systems. The halforder systems are represented in a Park dq axis equivalent circuit as impedances modelled by halforder transmittances. Using a direct method based on the approximation...

[AEiE] Selected topics of electrical engineering  models of electrical machines
Kursy Online{mlang pl} Dyscyplina: automatyka, elektronika i elektrotechnika Zajęcia fakultatywne dla doktorantów II roku Prowadzący: dr hab. inż. Andrzej Wilk, prof. PG, prof. dr hab. inż. Zbigniew Krzemiński Liczba godzin: 15 Forma zajęć: wykład {mlang} {mlang en} Discipline: control, electronic and electrical engineering Facultative course for 2ndyear PhD students Academic teachers: dr hab. inż. Andrzej Wilk, prof. PG, prof....

Identification of Parameters Influencing the Accuracy of the Solution of the Nonlinear Muskingum Equation
PublikacjaTwo nonlinear versions of the Muskingum equation are considered. The difference between both equations relates to the exponent parameter. In the first version, commonly used in hydrology, this parameter is considered as free, while in the second version, it takes a value resulting from the kinematic wave theory. Consequently, the first version of the equation is dimensionally inconsistent, whereas the proposed second one is consistent. It...

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...

Numerical Characterization of Thresholds for the Focusing 1d Nonlinear Schrödinger Equation
PublikacjaThe focusing nonlinear Schrödinger equation arises in various physical phenomena and it is therefore of interest to determine mathematical conditions on the initial data that guarantee whether the corresponding solution will blow up in finite time or exist globally in time. We focus on solutions to the mass‐supercritical nonlinear Schrödinger equation (1) in 1D case. In particular, we investigate numerical thresholds between blow...

Methods of solving the Atkins equation determine shear angle with taking into consideration a modern fracture mechanics
PublikacjaIn the paper are presented methods of solving nonlinear Atkins equation . The Atkins equation describe shear angle with taking into account properties of material cutting. To solve Atkins equation has been used iterative methods: Newton method and simplified method of simple iteration. Method of simple iteration is presented in the form of Java application.

Electronically Excited States in Solution via a Smooth Dielectric Model Combined with EquationofMotion Coupled Cluster Theory
PublikacjaWe present a method for computing excitation energies for molecules in solvent, based on the combination of a minimal parameter implicit solvent model and the equationofmotion coupledcluster singles and doubles method (EOMCCSD). In this method, the solvent medium is represented by a smoothly varying dielectric function, constructed directly from the quantum mechanical electronic density using only two tunable parameters. The...

Modeling of medium flow processes in transportation pipelines  the synthesis of their statespace models and the analysis of the mathematical properties of the models for leak detection purposes
PublikacjaThe dissertation concerns the issue of modeling the pipeline flow process under incompressible and isothermal conditions, with a target application to the leak detection and isolation systems. First, an introduction to the modelbased process diagnostics is provided, where its basic terminology, tools, and methods are described. In the following chapter, a review of the state of the art in the field of leak detection and isolation...

A highaccuracy method of computation of xray waves propagation through an optical system consisting of many lenses
PublikacjaThe propagation of Xray waves through an optical system consisting of many Xray refractive lenses is considered. Two differential equations are contemplated for solving the problem for electromagnetic wave propagation: first – an equation for the electric field, second – an equation derived for a complex phase of an electric field. Both equations are solved by the use of a finitedifference method. The simulation error is estimated...