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Search results for: commutation unit
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Low-cost multi-objective optimization and experimental validation of UWB MIMO antenna
PublicationPurpose–The purpose of this paper is to validate methodologies for expedited multi-objective designoptimization of complex antenna structures both numerically and experimentally.Design/methodology/approach–The task of identifying the best possible trade-offs between theantenna size and its electrical performance is formulated as multi-objective optimization problem.Algorithmic frameworks are described for finding Pareto-optimal...
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Simulation-driven design of compact ultra-wideband antenna structures
PublicationPurpose–The purpose of this paper is to investigate strategies and algorithms for expedited designoptimization and explicit size reduction of compact ultra-wideband (UWB) antennas.Design/methodology/approach–Formulation of the compact antenna design problem aiming atexplicit size reduction while maintaining acceptable electrical performance is presented. Algorithmicframeworks are described suitable for handling various design situations...
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Rapid design optimization of antennas using variable-fidelity EM models and adjoint sensitivities
PublicationPurpose – Development of techniques for expedited design optimization of complex and numerically expensive electromagnetic (EM) simulation models of antenna structures validated both numerically and experimentally. The paper aims to discuss these issues. Design/methodology/approach – The optimization task is performed using a technique that combines gradient search with adjoint sensitivities, trust region framework, as well as...
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Variable-fidelity CFD models and co-Kriging for expedited multi-objective aerodynamic design optimization
PublicationPurpose – Strategies for accelerated multi-objective 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,...
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Expedited antenna optimization with numerical derivatives and gradient change tracking
PublicationDesign automation has been playing an increasing role in the development of novel antenna structures for various applications. One of its aspects is electromagnetic (EM)-driven design closure, typically applied upon establishing the antenna topology, and aiming at adjustment of geometry parameters to boost the performance figures as much as possible. Parametric optimization is often realized using local methods given usually reasonable...
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A framework for accelerated optimization of antennas using design database and initial parameter set estimation
PublicationThe purpose of this paper is to exploit a database of pre-existing designs to accelerate parametric optimization of antenna structures is investigated. Design/methodology/approach The usefulness of pre-existing designs for rapid design of antennas is investigated. The proposed approach exploits the database existing antenna base designs to determine a good starting point for structure optimization and its response sensitivities....
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Variable-fidelity shape optimization of dual-rotor wind turbines
PublicationPurpose Dual-rotor wind turbines (DRWTs) are a novel type of wind turbines that can capture more power than their single-rotor counterparts. Because their surrounding flow fields are complex, evaluating a DRWT design requires accurate predictive simulations, which incur high computational costs. Currently, there does not exist a design optimization framework for DRWTs. Since the design optimization of DRWTs requires numerous model...
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RANS-based design optimization of dual-rotor wind turbines
PublicationPurpose An improvement in the energy efficiency of wind turbines can be achieved using dual rotors. Because of complex flow physics, the design of dual-rotor wind turbines (DRWTs) requires repetitive evaluations of computationally expensive partial differential equation (PDE) simulation models. Approaches for solving design optimization of DRWTs constrained by PDE simulations are investigated. The purpose of this study is to determine...
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Expedited optimization of antenna input characteristics with adaptive Broyden updates
PublicationSimulation-driven adjustment of geometry and/or material parameters is a necessary step in the design of contemporary antenna structures. Due to their topological complexity, other means, such as supervised parameter sweeping, does not usually lead to satisfactory results. On the other hand, rigorous numerical optimization is computationally expensive due to a high cost of underlying full-wave electromagnetic (EM) analyses, otherwise...
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Fast multi-objective design optimization of microwave and antenna structures using data-driven surrogates and domain segmentation
PublicationPurpose Strategies and algorithms for expedited design optimization of microwave and antenna structures in multi-objective setup are investigated. Design/methodology/approach Formulation of the multi-objective design problem oriented towards execution of the population-based metaheuristic algorithm within the segmented search space is investigated. Described algorithmic framework exploit variable fidelity modeling, physics- and...
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Rapid multi-objective optimization of antennas using nested kriging surrogates and single-fidelity EM simulation models
PublicationEver increasing performance requirements make the design of contemporary antenna systems a complex and multi-stage process. One of the challenges, pertinent to the emerging application areas but also some of the recent trends (miniaturization, demands for multi-functionality, etc.), is the necessity of handling several performance figures such as impedance matching, gain, or axial ratio, often over multiple frequency bands. The...
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Patch size setup and performance/cost trade-offs in multi-objective EM-driven antenna optimization using sequential domain patching
PublicationPurpose This paper aims to assess control parameter setup and its effect on computational cost and performance of deterministic procedures for multi-objective design optimization of expensive simulation models of antenna structures. Design/methodology/approach A deterministic algorithm for cost-efficient multi-objective optimization of antenna structures has been assessed. The algorithm constructs a patch connecting extreme Pareto-optimal...
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On deterministic procedures for low-cost multi-objective design optimization of miniaturized impedance matching transformers
PublicationPurpose This paper aims to investigate deterministic strategies for low-cost multi-objective design optimization of compact microwave structures, specifically, impedance matching transformers. The considered methods involve surrogate modeling techniques and variable-fidelity electromagnetic (EM) simulations. In contrary to majority of conventional approaches, they do not rely on population-based metaheuristics, which permit lowering...
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Reliable data-driven modeling of high-frequency structures by means of nested kriging with enhanced design of experiments
PublicationData-driven (or approximation) surrogate models have been gaining popularity in many areas of engineering and science, including high-frequency electronics. They are attractive as a way of alleviating the difficulties pertinent to high computational cost of evaluating full-wave electromagnetic (EM) simulation models of microwave, antenna, and integrated photonic components and devices. Carrying out design tasks that involve massive...
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Fast tolerance-aware design optimization of miniaturized microstrip couplers using variable-fidelity EM simulations and re-sponse features
PublicationManufacturing tolerances and other types of uncertainties may considerably affect operation and performance of microwave components and systems. Quantification of these effects is therefore an important part of the design process. It is even more important to obtain designs whose sensitivity to parameter deviations is reduced as much as possible. All of these require statistical analysis carried out at the level of electromagnetic...
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The large rotations theory of elasto-viscoplastic shells subjected to thedynamic and thermal loads.
PublicationPrzedstawiono problemy sprężysto- lepkoplastycznej analizy geometrycznie nieliniowych płyt i powłok poddanych obciążeniom dynamicznym w różnych temperaturach. W obliczeniach zastosowano teorię ścinania pierwszego rzędu i konstytutywne prawo Chaboche´a w wariantach z uwzględnieniem wpływu temperatury na stałe materiałowe. Do całkowania równań ruchu użyto metody różnic centralnych, a do całkowania równań konstytutywnych regułę...
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Runtime Visualization of Application Progress and Monitoring of a GPU-enabled Parallel Environment
PublicationThe paper presents design, implementation and real life uses of a visualization subsystem for a distributed framework for parallelization of workflow-based computations among clusters with nodes that feature both CPUs and GPUs. Firstly, the proposed system presents a graphical view of the infrastructure with clusters, nodes and compute devices along with parameters and runtime graphs of load, memory available, fan speeds etc. Secondly,...
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Performance and Power-Aware Modeling of MPI Applications for Cluster Computing
PublicationThe paper presents modeling of performance and power consumption when running parallel applications on modern cluster-based systems. The model includes basic so-called blocks representing either computations or communication. The latter includes both point-to-point and collective communication. Real measurements were performed using MPI applications and routines run on three different clusters with both Infiniband and Gigabit Ethernet...
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Research and Analysis of Accuracy of Location Estimation in Inertial Navigation System
PublicationIn the article the research and analysis of digital signal processing and its influence on accuracy of location estimation in developed inertial navigation system was presented. The purpose of the system is to localize moving people in indoor environment. During research a measuring unit for recording selected movement parameters was made. In the article were also described author’s inertial navigation algorithms.
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A Method of MOS Evaluation for Video Based Services
PublicationThis paper deals with a method for QoE evaluation for the services transmitting large amount of data perceived by the end user in relatively short time periods, e.g. streaming video in mobile operator...
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How to evaluate methods used in chemical laboratories in terms of the total chemical risk? – a ChlorTox Scale
PublicationReliable assessment of the health and environmental risk associated with the use of chemicals is critical to ob- jectively evaluate the greenness and whiteness of an analytical method. An objective and useful way of risk assessment should take into account all the relevant properties of used substances, their actual amounts needed for application of the method, and quantify the assessment result using a standardized unit. This...
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Energy storage device based on flywheel, power converters and Simulink real-time
PublicationThis electronic document is a “live” template and already defines the components of your paper [title, text, heads, etc.] in its style sheet. Paper presents information on Energy Storage Device based on Flywheel and bi-directional IGBT Power Converters – designed for LINTE^2 laboratory owned by Gdansk University of Technology in Poland. Paper is divided into four sections. First section of the paper provides introductory information...
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Cooperation of ORC installation with a gas boiler as a perspective co-generation system for households
PublicationThis paper reports tests of an innovative micro-CHP unit prototype, consisting of a traditional gas boiler and organic Rankine cycle (ORC), which incorporates original system components such as an axial vapour microturbine, evaporator and condenser. The system co-generates heat and electricity for a single household or a group of households. Electricity is only a by-product during production of heat. While testing the prototype,...
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POSSIBILITY OF ASSESSMENT OF OPERATION OF SLIDING BEARINGS IN PISTON-CRANK MECHANISMS OF DIESEL ENGINES WITH REGARD TO LOAD AND TIME OF CORRECT WORK OF THE BEARINGS BY APPLYING ACOUSTIC EMISSION AS A DIAGNOSTIC SIGNAL
PublicationAbstract: The paper presents a possibility of determining (assessing) operation of sliding bearings with multilayer bushings in crank-piston mechanisms of diesel engines. Properties of load and wear, particularly fatigue and abrasive, are characterized in general. Acoustic emission as a diagnostic signal was proved to be useful for detection of the wear of sliding and barrier layers. Results of measurements of acoustic emission...
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Exergy Losses in the Szewalski Binary Vapor Cycle
PublicationIn this publication, we present an energy and exergy analysis of the Szewalski binary vapor cycle based on a model of a supercritical steam power plant. We used energy analysis to conduct a preliminary optimization of the cycle. Exergy loss analysis was employed to perform a comparison of heat-transfer processes, which are essential for hierarchical cycles. The Szewalski binary vapor cycle consists of a steam cycle bottomed with...
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Experimental Investigations on the Influence of Coil Arrangement on Melting/Solidification Processes
PublicationThe latent heat thermal energy storage units are very popular because of their high energy density and almost close to constant temperature during the charging/discharging. In the present study has been proposed new shell-and-coil geometry with a shifted coil position to enhance the performance of phase change thermal magazine. The experimental investigations have been performed both for the melting and solidification process of...
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Evidence for SrHo2O4 and SrDy2O4 as model J1- J2 zigzag chain materials
PublicationNeutron diffraction and inelastic spectroscopy is used to characterize the magnetic Hamiltonian of SrHo2O4 and SrDy2O4. Through a detailed computation of the crystal-field levels we find site-dependent anisotropic single-ion magnetism in both materials, and diffraction measurements show the presence of strong one-dimensional spin correlations.Our measurements indicate that competing interactions of the zigzag chain, combinedwith...
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Transcriptomic landscape of blood platelets in healthy donors
PublicationBlood platelet RNA-sequencing is increasingly used among the scientific community. Aberrant platelet transcriptome is common in cancer or cardiovascular disease, but reference data on platelet RNA content in healthy individuals are scarce and merit complex investigation. We sought to explore the dynamics of platelet transcriptome. Datasets from 204 healthy donors were used for the analysis of splice variants, particularly with...
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Computationally Efficient Surrogate-Assisted Design of Pyramidal-Shaped 3D Reflectarray Antennas
PublicationReflectarrays (RAs) have been attracting considerable interest in the recent years due to their appealing features, in particular, a possibility of realizing pencil-beam radiation patterns, as in the phased arrays, but without the necessity of incorporating the feeding networks. These characteristics make them attractive solutions, among others, for satellite communications or mobile radar antennas. Notwithstanding, available microstrip...
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Transcriptomic landscape of blood platelets in healthy donors
PublicationBACKGROUND Blood platelet RNA-sequencing is increasingly used among the scientific community. Aberrant platelet transcriptome is common in cancer or cardiovascular disease, but reference data on platelet RNA content in healthy individuals are scarce and merit complex investigation. METHODS We sought to explore the dynamics of platelet transcriptome. Datasets from 204 healthy donors were used for the analysis of splice variants,...
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Steam turbines governors in power system restoration process
PublicationThe paper discusses problems related to electric power system restoration process. The turbine controller operating mode influence in small subsystem is analyzed. There are considered abilities, advantages and drawbacks of the controller's two operating modes: power control and speed (frequen-cy) control, to rebuild electric power system from a single generating unit to a few parallel running generators.
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Design and investigations of the ethanol microturbine
PublicationThe paper presents the results of the design analysis and experimental investigations of the microturbine set consisting of the microturbine with partial admission and permanent magnet generator. The microturbine was designed for operation with the vapour of ethanol as a working fluid. Microturbine unit was tested for different parameters of the working fluid and varying the electrical load. The examples and the comparison between...
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Genetic Positioning of Fire Stations Utilizing Grid-computing Platform
PublicationA chapter presents a model for determining near-optimal locations of fire stations based on topography of a given area and location of forests, rivers, lakes and other elements of the site. The model is based on principals of genetic algorithms and utilizes the power of the grid to distribute and execute in parallel most performance-demanding computations involved in the algorithm.
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LINEAR CHARACTERISTICS OF THE SLOSHING PHENOMENON FOR THE PURPOSE OF ON-BOARD SHIP'S STABILITY ASSESSMENT
PublicationThe paper presents results of experimental research and numerical simulations of the sloshing phenomenon. The research was focused on computation of the heeling moment affecting stability of a vessel. The proposed linearisation enables application of the results to the assessment of the ship's stability. The dependence of the heeling moment upon localisation of a tank in the ship's hull is analysed. The heeling moment obtained...
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Comprehensive compensation of grid current distortion by shunt active power filters
PublicationThe paper presents a comprehensive approach to the compensation of grid current distortion in shunt active power filter systems. Four sources of current distortion are addressed: imperfect grid synchronization caused by the distortion in the grid voltages, time delays in the evaluation of grid voltages and computation of compensating currents, fluctuations of the dc bus voltage, and the distortion of inverter output voltages due...
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Efficient quadrature for fast oscillating integralof paraxial optics
PublicationThe study concerns the determination of quadrature for the integral solutionof the paraxial wave equation. The difficulty in computation of the integral isassociated with the rapid change of the integrand phase. The developed quadraturetakes into account the fast oscillating character of the integrand. The presentedmethod is an alternative to the commonly used methods based on the use of theFourier transform. The determination...
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An Enhanced Reduced Basis Method for Wideband Finite Element Method Simulations
PublicationIn this paper, we present a novel strategy for selecting expansion points in the reduced basis method. A single computation of the error estimator is used to select a few expansion points in the multi-parameter space simultaneously. The number of selected points is determined adaptively, based on the accuracy of the current reduced model. The reliability and efficiency of this proposed approach are illustrated by numerical tests...
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The Concept of Geodetic Analyses of the Measurement Results Obtained by Hydrostatic Leveling
PublicationThe article discusses the issue of hydrostatic leveling. Its application is presented in structural health monitoring systems in order to determine vertical displacements of controlled points. Moreover, the article includes a complete computation scheme that utilizes the estimation from observation differences, allowing the elimination of the influence of individual sensors’ systematic errors. The authors suggest two concepts of...
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Intramolecular interactions in crystals of tris(2,6-diisopropylphenoxy)silanethiol and its sodium salts
PublicationHydrolytically stable tris(2,6-diisopropylphenoxy)silanethiol has been obtained and reacted with sodium. Solid state interactions within and between the molecules of tris(2,6-diisopropylphenoxy)silanethiol including S-H---π-interactions between the S-H unit and the π-system of the arene have been analyzed. The interactions are documented by X-ray diffraction and FT-IR spectroscopy.
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Investigation of the influence of capilary effect on operation of the loop heat pipe
PublicationIn the paper presented are studies on the inestigation of the capillary forces effect inducted in the porous structure of a loop heat pipe using water and ethanol ad test fluids. The potential application of such effects is for example in the evaporator of the domestic micro-CHP unit, where the reduction of pumping power could be obtained. Preliminary analysis of the results indicates water as having the best potential for developing...
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Equitable and semi-equitable coloring of cubic graphs and its application in batch scheduling
PublicationIn the paper we consider the problems of equitable and semi-equitable coloring of vertices of cubic graphs. We show that in contrast to the equitable coloring, which is easy, the problem of semi-equitable coloring is NP- complete within a broad spectrum of graph parameters. This affects the complexity of batch scheduling of unit-length jobs with cubic incompatibility graph on three uniform processors to minimize...
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Boundary vlue problems for difference equations with causal operators
PublicationPraca dotyczy problemów brzegowych dla równań różnicowych.Podano warunki dostateczne na istnienie ekstremalnych rozwiązań stosując metodę iteracji monotonicznych.
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NO-BROADCASTING OF NON-SIGNALLING BOXES VIA OPERATIONS WHICH TRANSFORM LOCAL BOXES INTO LOCAL ONES
PublicationWe deal with families of probability distributions satisfying non-signalling condition, called non-signalling boxes and consider a class of operations that transform local boxes into local ones (the one that admit LHV model). We prove that any operation from this class cannot broadcast a bipartite non-local box with 2 binary inputs and outputs. We consider a function called anti-Robustness which can not decrease under these operations....
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A new approach to numerical solution of fixed-point problems and its application to delay differential equations
PublicationW pracy rozpatruje się pewne aproksymacje punktu stałego ciągłego operatora A odwzorowującego przestrzeń metryczną w siebie. Wspomniany punkt stały przybliża się tzw. epsilon przybliżonym punktem stałym z przestrzeni skończenie wymiarowej. Udowodnione zostało twierdzenie dające warunki konieczne i dostateczne istnienia punktu stałego w ogólnej przestrzeni metrycznej. Warunki te wyrażone są w terminach epsilon przybliżonego punktu...
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Initial value problems for neutral fractional differential equations involving a Riemann-Liouville derivative
PublicationBadano równania neutralne typu ułamkowego z odchylonym argumentem. Podano warunki dostateczne na istnienie jednego rozwiązania.
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Existence of solutions for a coupled system of difference equations with cousal operators
PublicationPraca dotyczy układów równań różnicowych. Podano warunki dostateczne na istnienie rozwiązań takich problemów. Badano również nierówności różnicowe.
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Fractional problems with advanced arguments
PublicationThis paper concerns boundary fractional differential problems with advanced arguments. We investigate the existence of initial value problems when the initial point is given at the end point of an interval. Nonhomogeneous linear fractional differential equations are also studied. The existence of solutions for fractional differential equations with advanced arguments and with boundary value problems has been investigated by using...
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Positive solutions to fractional differential equations involving Stieltjes integral conditions
PublicationIn this paper, we investigate nonlocal boundary value problems for fractional differential equations with dependence on the first-order derivatives and deviating arguments. Sufficient conditions which guarantee the existence of at least three positive solutions are new and obtained by using the Avery–Peterson theorem. We discuss problems (1) and (2) when argument b can change the character on [0, 1], so in some subinterval I of...
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Monotone iterative method for first-order differential equations at resonance
PublicationThis paper concerns the application of the monotone iterative technique for first-order differential equations involving Stieltjes integrals conditions. We discuss such problems at resonance when the measure in the Stieltjes integral is positive and also when this measure changes the sign. Sufficient conditions which guarantee the existence of extremal, unique and quasi-solutions are given. Three examples illustrate the results.
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Green function diagonal for a class of heat equations
PublicationA construction of the heat kernel diagonal is considered as element of generalized zeta function theory, which gradient at the origin defines determinant of a differential operator in a technique for regularizing quadratic path integral. Some classes of explicit expressions of the Green function in the case of finite-gap potential coefficient of the heat equation are constructed. An algorithm and program for Mathematica are presented...