scholarly journals Drūkšiai lake (Ignalina NPP cooler) dynamics of the ichthyocenose

2012 ◽  
Vol 53 ◽  
Author(s):  
Donatas Švitra ◽  
Giedrius Žemaitis
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Numerical Solutions ◽  
Simulation Program ◽  
Lake Ecosystem ◽  
Thermal Loads ◽  
Lake Dynamics

This article describes the existing Drūkšiai lake ecosystem. After setting up the integrity of this mathematical model (2.1)–(2.2) thermal loads there are simulated Drūkšiai Lake dynamics of the ichthyocenose. It is done by using Runge–Kut IV method from this simulation program “ModelMaker”. The model numerical solutions of F1–F9 are compared with experimental data for the monitoring of fish. This dynamics is simulated by the year 2010 and projected to 2020.

scholarly journals Mathematical model of the ichtyocenose with delays

2010 ◽  
Vol 51 ◽  
Author(s):  
Donatas Švitra ◽  
Giedrius Žemaitis
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Numerical Solutions ◽  
Simulation Program ◽  
Curonian Lagoon ◽  
The Mathematical Model

This article describes the authors’ work the existing ecosystem in the Curonian Lagoon. Using the mathematical model of the ichtyocenose (1)–(2) is simulated the dynamics of the ichtyocenose in the Curonian Lagoon. It is done by using Runge–Kut IV method from this simulation program ModelMaker. The model numerical solutions of F1 - F8 are compared with the experimental data for the monitoring of fish. The dynamics is projected to the year 2016.

A Model for Flow Distribution in Manifolds

1971 ◽  
Vol 93 (1) ◽  
pp. 7-12 ◽  
Author(s):  
R. A. Bajura
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Analytical Model ◽  
Distribution Systems ◽  
Numerical Solutions ◽  
Flow Behavior ◽  
Flow Distribution ◽  
Analytical Investigation ◽  
Momentum Balance ◽  
Distribution Equation

An analytical investigation of the performance of flow distribution systems was conducted for both intake and exhaust manifolds. Primary emphasis was placed on configurations in which the lateral tubes formed sharp-edged junctions at right angles to the manifold axis. A mathematical model describing the flow behavior at a discreet branch point was formulated in terms of a momentum balance along the manifold. The model was extended to the case of continuous discharge or intake for a uniformly porous manifold. Numerical solutions of the governing flow distribution equation were obtained and compared with experimental data. Dimensionless parameters characterizing the performance of manifolds were formulated from the analytical model.

On the modelling of turbulent flow over low-angle sand dunes

2019 ◽  
Author(s):  
И.И. Потапов ◽  
К.С. Снигур ◽  
Г.И. Цой
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Shear Stress ◽  
Turbulent Flow ◽  
River Flow ◽  
Numerical Solutions ◽  
Control Volume ◽  
Sand Dunes ◽  
Wall Function ◽  
Wall Functions

Предложена математическая модель задачи о движении двумерного турбулентного потока жидкости в напорном канале с волнистым дном. Математическая модель включает уравнения Рейнольдса, уравнения переноса кинетической энергии и диссипации турбулентности, приведенные к квазигидродинамическому виду. Предложен алгоритм решения задачи с помощью метода контрольных объемов и метода конечных элементов. Численно решена задача о движении турбулентного потока над неподвижными пологими песчаными дюнами. Выполнено сравнение полученных расчетов с экспериментальными данными. Purpose. The aim of the paper is the development of mathematical models describing a turbulent river flow along gently sloping dunes and allowing estimation of the contribution of gently sloping dunes on the flow hydraulic resistance. Methodology. A quasi-hydrodynamic form of the classical RANS equations are used for describing the hydrodynamic flow. The standard k model is used for the turbulence viscosity while the equations have been transformed to the quasi-hydrodynamic form. A wall functions method is used for describing the flow near solid channel wall. Results. A new mathematical model for the problem of turbulent flow in a pressure channel with low-angle dunes is proposed. An algorithm for solving the problem is proposed. It is based on the control volume method and the finite element method. The problem of the turbulent flow over 6 fixed low-angle sand dunes is solved numerically. Numerical solutions are obtained with four different wall functions. A comparative analysis of the obtained solutions with the experimental data is carried out. Findings. It is shown that the proposed mathematical model describes the turbulent flow over low-angle dunes qualitatively and quantitatively. The solution obtained with the Volkov wall function provides the best agreement with the experiment. It is found out that the bed shear stress obtained in the near-wall computational cell by the wall functions method does not qualitatively agree with the experimental data for all considered wall functions. At the same time, the shear stress obtained in the next calculation cell agrees with the experimental data qualitatively and quantitatively. The average relative error of the shear stress obtained with the Volkov wall function is 6.84.

The substantiation of the formalized estimation of effectiveness of technological and production systems

2018 ◽  
Vol 15 (1) ◽  
pp. 169-181
Author(s):  
M. I. Sidorov ◽  
М. Е. Stavrovsky ◽  
V. V. Irogov ◽  
E. S. Yurtsev
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Production Systems ◽  
Van Der Pol

Using the example of van der Pol developed a mathematical model of frictional self-oscillations in topochemically kinetics. Marked qualitative correspondence of the results of calculation performed using the experimental data of researchers.

The lake ecosystem simulation program

1995 ◽  
Vol 31 (8) ◽  
pp. 367-370
Author(s):  
J. Heringa ◽  
H. Hylkema ◽  
M. Kroes ◽  
E. Ludden ◽  
P. G. van Schaick Zillesen
Keyword(s):  
Mathematical Model ◽  
Water Resources ◽  
Computer Program ◽  
Water Resources Management ◽  
Lake Ecosystem ◽  
Original Research ◽  
Ecological Processes ◽  
Resources Management ◽  
Lake Ecology ◽  
Ecosystem Simulation

The computer program LAKE simulates a shallow lake ecosystem. The program is based on a mathematical model. In the model the most important aspects of several models for water resources management are integrated (Collins and Wlosinski, 1988; Jørgensen, 1976; Jørgensen et al., 1978; Scheffer, 1988). Furthermore, the model describes several ecological processes that have not yet been described by lake-ecosystem models so far. In the computer program, the mathematical model and an advanced, object oriented, user interface are combined. Following this approach the use of the original research models was extended to a use for the purpose of teaching lake ecology. We suggest that the same approach may be followed to open research models to other groups concerned with water resources management, such as management authorities, industry, agricultural extension, nature conservation and recreation.

scholarly journals Exhaust Noise Reduction by Application of Expanded Collecting System in Pneumatic Tools and Machines

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1592
Author(s):  
Dominik Gryboś ◽  
Jacek S. Leszczyński ◽  
Dorota Czopek ◽  
Jerzy Wiciak
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Noise Reduction ◽  
Sound Pressure ◽  
Acoustic Pressure ◽  
Pressure Level ◽  
Computational Results ◽  
Noise Measurements ◽  
Exhaust Noise ◽  
Collecting System

In this paper, we demonstrate how to reduce the noise level of expanded air from pneumatic tools. Instead of a muffler, we propose the expanded collecting system, where the air expands through the pneumatic tube and expansion collector. We have elaborated a mathematical model which illustrates the dynamics of the air flow, as well as the acoustic pressure at the end of the tube. The computational results were compared with experimental data to check the air dynamics and sound pressure. Moreover, the study presents the methodology of noise measurement generated in a pneumatic screwdriver in a quiet back room and on a window-fitting stand in a production hall. In addition, we have performed noise measurements for the pneumatic screwdriver and the pneumatic screwdriver on an industrial scale. These measurements prove the noise reduction of the pneumatic tools when the expanded collecting system is used. When the expanded collecting system was applied to the screwdriver, the measured Sound Pressure Level (SPL) decreased from 87 to 80 dB(A).

Modal Analysis of the Axial Compressor Blade: Advanced Time-Dependent Electronic Interferometry and Finite Element Method

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mykhaylo Tkach ◽  
Serhii Morhun ◽  
Yuri Zolotoy ◽  
Irina Zhuk
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Finite Element ◽  
High Reliability ◽  
Axial Compressor ◽  
Time Dependent ◽  
Experimental Setup ◽  
Vibration Modes ◽  
Compressor Blades ◽  
Isoparametric Finite Element

AbstractNatural frequencies and vibration modes of axial compressor blades are investigated. A refined mathematical model based on the usage of an eight-nodal curvilinear isoparametric finite element was applied. The verification of the model is carried out by finding the frequencies and vibration modes of a smooth cylindrical shell and comparing them with experimental data. A high-precision experimental setup based on an advanced method of time-dependent electronic interferometry was developed for this aim. Thus, the objective of the study is to verify the adequacy of the refined mathematical model by means of the advanced time-dependent electronic interferometry experimental method. The divergence of the results of frequency measurements between numerical calculations and experimental data does not exceed 5 % that indicates the adequacy and high reliability of the developed mathematical model. The developed mathematical model and experimental setup can be used later in the study of blades with more complex geometric and strength characteristics or in cases when the real boundary conditions or mechanical characteristics of material are uncertain.

scholarly journals Modelling time efficiency of cobot-supported kit preparation

2019 ◽  
Vol 106 (5-6) ◽  
pp. 2227-2241 ◽  
Author(s):  
Patrik Fager ◽  
Martina Calzavara ◽  
Fabio Sgarbossa
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Cycle Time ◽  
Laboratory Experiments ◽  
Spare Parts ◽  
Batch Preparation ◽  
Assembly Quality ◽  
Numerical Example ◽  
Business To Business ◽  
Support Time

AbstractKitting – meaning to supply assembly with components in presorted kits – is widely seen as beneficial for assembly quality and efficiency when there is a multitude of component variants. However, the process by which kits are prepared – the kit preparation – is labour-intensive, and kit errors are problematic at assembly processes. The use of robotics to support kit preparation has received some attention by researchers, but literature is lacking with respect to how collaborative robots – cobots – can support kit preparation activities. The purpose of this paper is to identify the potential of a cobot to support time-efficient batch preparation of kits. To address the purpose, the paper presents a mathematical model for estimation of the cycle time associated with cobot-supported kit preparation. The model is applied in a numerical example with experimental data from laboratory experiments, and cobot-supported kit preparation is compared with manual kit preparation. The findings suggest that cobot-supported kit preparation is beneficial with diverse kits and smaller components quantities per SKU (Stock Keeping Unit) and provides less variability of the outcome, when compared to manual kit preparation. The paper reveals several insights about cobot-supported kit preparation that can be valuable for both academics and practitioners. The model developed can be used by practitioners to assess the potential of cobots to support kit-batch preparation in association with assembly, spare parts, repair and maintenance, or business to business industry.

Mathematical Model of the Sintering Process of Iron-Copper Bearings

2007 ◽  
Vol 23 ◽  
pp. 119-122
Author(s):  
Cristina Teișanu ◽  
Stefan Gheorghe ◽  
Ion Ciupitu
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Mathematical Model ◽  
Regression Analysis ◽  
Function Optimization ◽  
Chemical Compositions ◽  
Sintering Process ◽  
Molybdenum Disulphide ◽  
Iron Copper ◽  
Antifriction Properties

The most important features of the self-lubricating bearings are the antifriction properties such as friction coefficient and wear resistence and some mechanical properties such as hardness, tensile strength and radial crushing strength. In order to improve these properties new antifriction materials based on iron-copper powders with several additional components (tin, lead and molybdenum disulphide) have been developed by PM techniques. To find the optimal relationship between chemical compositions, antifriction and mechanical properties, in this paper a mathematical model of the sintering process is developed, which highlighted the accordance of the model with data by regression analysis. For the statistical processing of the experimental data the VH5 hardness values of the studied materials were considered. The development of mathematical model includes the enunciation of the model, the establishment of the performance function (optimization) and the establishment of the model equations and verifying. The accordance of the model with experimental data has been highlighted by regression analysis

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