Calculating the flows of a viscoplastic medium in tubes using the local variation method

1970 ◽  
Vol 1 (6) ◽  
pp. 129-131
Author(s):  
N. V. Banichuk
Keyword(s):  
Local Variation ◽  
Viscoplastic Medium ◽  
Variation Method

scholarly journals On the search of a potential displacement surface with the use of the local variation method

2019 ◽  
Vol 138 ◽  
pp. 02013
Author(s):  
Tamara Makeeva ◽  
Vitaly Trofimov
Keyword(s):  
Local Variation ◽  
Variation Method ◽  
Direct Iteration ◽  
Selection Of

The purpose of the article is to develop some basic conceptual provisions, algorithm and method of the search of the surface of the smallest resistance to shift, based on the minimization of durability functionality. The algorithm uses the approach, based on the direct iteration of various trial displacement surfaces and the selection of the surface with the minimum functionality value from these surfaces with the method of local variations. The coefficients allowing to estimate the possibility of rocks destruction at various sites of this surface are offered. The results of the search of a potential destruction surface for a pit board are given as an example.

Solving optimal filtering problems by local variation method

1992 ◽  
Vol 60 (4) ◽  
pp. 1603-1606
Author(s):  
V. A. Stoyan ◽  
O. N. Arievich
Keyword(s):  
Local Variation ◽  
Variation Method ◽  
Optimal Filtering

APPLICATION OF THE LOCAL VARIATION METHOD FOR SOLVING FIRE SAFETY PROBLEMS OF OBJECTS OF PROTECTION

2021 ◽  
pp. 26-34
Author(s):  
Валерий Геннадьевич Шамонин ◽  
Станислав Анатольевич Зуев ◽  
Петр Алексеевич Леончук ◽  
Светлана Юрьевна Хатунцева ◽  
Елена Николаевна Барановская
Keyword(s):  
Fire Protection ◽  
Fire Safety ◽  
Local Variation ◽  
Variation Method ◽  
Numerical Implementation ◽  
Test Results

Применение метода локальных вариаций для решения прикладных задач, в том числе пожарной охраны, может быть сопряжено с преодолением возможных трудностей (как аналитического характера, так и численной реализации). Для последующего использования этого метода проведено его тестирование на так называемых «жестких» примерах, позаимствованных из литературы. Хотя результаты тестирования следует признать не более чем удовлетворительными, применимость метода при решении конкретных прикладных задач можно считать оптимистичной. Application of the local variations method for solving applied problems, including fire protection ones, can be associated with overcoming possible difficulties (both of an analytical nature and of a numerical implementation). For the following use of this method it was tested on the so-called "hard" examples taken from the literature. Although the test results should be considered like satisfactory, the applicability of the method for solving specific applied problems can be considered as optimistic.

Assessment of fire protection distances between the objects of different purpose taking into account the cooling of external surfaces

2021 ◽  
pp. 60-66
Author(s):  
Алексей Сергеевич Барановский ◽  
Дмитрий Викторович Ушаков ◽  
Валерий Геннадьевич Шамонин ◽  
Станислав Анатольевич Зуев ◽  
Светлана Юрьевна Хатунцева
Keyword(s):  
Fire Safety ◽  
Optimization Problems ◽  
Target Function ◽  
Local Variation ◽  
Small Dimension ◽  
Variation Method ◽  
Test Results ◽  
Finite Dimensional ◽  
New Type ◽  
Derivatives Of

Проведена серия расчетов по оценке температуры при пожаре в режиме, регулируемом вентиляцией, поскольку при этом достигается максимальное значение температуры. Исследуется радиационный и конвективный теплообмен с наружными поверхностями стен помещения. Рассмотрен случай пожара в помещениях складского типа. The application of local variation method for solving fire safety problems with variational formulation (continuous or finite-dimensional) makes it possible to significantly simplify the procedure of mathematical calculations for fire modeling and calculation tasks in the field of fire safety. The choice of the local variation method as a method of direct search for the conditional optimization problem (if there are restrictions) is associated with the absence of the need to calculate the derivatives of the target function (gradient and Hesse matrix). This saves the user from the tedious procedure of getting analytical or finite-difference expressions for the specified derivatives. This choice seems also to be due to the task of non-differentiable optimization. The article provides a justification for choosing the local variation method as one of the alternating-variable descent methods, developed for problems of thermal conductivity, control, etc. Specific features in the implementation of this algorithm are noted, as well as test examples of its application on several well-known test examples representing poorly conditioned “functionals” of small dimension. There are considered the methods of numerical implementation either by Hooke-Jeeves, which is one of the methods of coordinate descent developed for unconditional optimization problems, or by Nelder - Mead, one of the most effective methods if the number of variables does not exceed 6. Example researches showed that regularization contributes to the convergence of the method of local variations. The most effective one is a stabilizer that uses an exact solution. Some predominance of negative test results on the use of regularization is explained by insufficient conditionality of the examples used. This circumstance indicates the need for further search for optimal possibilities of using the method of local variations for applied problems. If it is necessary other stabilizers, not considered in the article, can be used. For the purpose of optimization of the formulated problem, it seems optimal to design a new type of stabilizers.

Modification of the Local Variation Method to Minimize the Functionals of the Elasticity Theory

2018 ◽  
Vol 931 ◽  
pp. 174-177
Author(s):  
Muaed M. Oshkhunov ◽  
Madina A. Dzhankulaeva ◽  
Fatima M. Nakhusheva ◽  
Maria M. Tkabisimova
Keyword(s):  
Finite Element Method ◽  
Inverse Problem ◽  
Finite Element ◽  
Elasticity Theory ◽  
Local Variation ◽  
Theory Of Elasticity ◽  
Variation Method ◽  
The Finite Element Method ◽  
Counting Time ◽  
Elastic Characteristics

In this paper a modification of the local variation method for minimizing the elasticity functionals, which reduces the counting time when varying them with small steps is proposed. Example of the solution of the inverse problem of the theory of elasticity by the finite element method is given. The problem of finding the elastic characteristics of a three-layer cable insulation, in which the annular stresses and deformations practically do not vary radially, is solved.

Exit-surface wave reconstruction using a focal series

1992 ◽  
Vol 50 (2) ◽  
pp. 988-989
Author(s):  
W.J. de Ruijter ◽  
M.R. McCartney ◽  
David J. Smith ◽  
J.K. Weiss
Keyword(s):  
Surface Wave ◽  
Spherical Aberration ◽  
Data Extraction ◽  
High Sensitivity ◽  
Geometric Distortion ◽  
Variation Method ◽  
Objective Lens ◽  
Immediate Reconstruction ◽  
Exit Surface ◽  
Electron Microscopes

Further advances in resolution enhancement of transmission electron microscopes can be expected from digital processing of image data recorded with slow-scan CCD cameras. Image recording with these new cameras is essential because of their high sensitivity, extreme linearity and negligible geometric distortion. Furthermore, digital image acquisition allows for on-line processing which yields virtually immediate reconstruction results. At present, the most promising techniques for exit-surface wave reconstruction are electron holography and the recently proposed focal variation method. The latter method is based on image processing applied to a series of images recorded at equally spaced defocus.Exit-surface wave reconstruction using the focal variation method as proposed by Van Dyck and Op de Beeck proceeds in two stages. First, the complex image wave is retrieved by data extraction from a parabola situated in three-dimensional Fourier space. Then the objective lens spherical aberration, astigmatism and defocus are corrected by simply dividing the image wave by the wave aberration function calculated with the appropriate objective lens aberration coefficients which yields the exit-surface wave.

Sign in / Sign up

Export Citation Format

Share Document