The Stability of Optimal Values in Problems of Discrete Programming

1975 ◽  
pp. 372-376
Author(s):  
V. R. Khachaturov
Keyword(s):  
Optimal Values ◽  
Discrete Programming ◽  
The Stability

scholarly journals SPECTRA OF THERMOSTIMULATED DEPOLARIZATION OF BIOCOMPOSITES WITH FILLERS OF BIOLOGICAL ORIGIN

2021 ◽  
Vol 5 (1(82)) ◽  
pp. 45-49
Author(s):  
E. Gojayev ◽  
V. Salimova ◽  
Sh. Alieva
Keyword(s):  
Surface Density ◽  
Fish Bone ◽  
Fish Scales ◽  
Biological Origin ◽  
Space Charges ◽  
High Pressure Polyethylene ◽  
Optimal Values ◽  
The Stability ◽  
Thermally Stimulated Depolarization ◽  
Volumetric Content

The paper presents the results of studying the spectra of thermally stimulated depolarization of high-pressure polyethylene modified with fillers of biocomposites with fillers of biological origin - fish bone and fish scales. It was revealed that the stability and surface density of space charges can be controlled by varying the volumetric content of biological fillers. The optimal values of bio-fillers that contribute to the stability of the surface density of the studied biocomposites have been determined.

scholarly journals The RAW Filter: An Improvement to the Robert–Asselin Filter in Semi-Implicit Integrations

2011 ◽  
Vol 139 (6) ◽  
pp. 1996-2007 ◽  
Author(s):  
Paul D. Williams
Keyword(s):  
Small Time ◽  
Time Stepping ◽  
Phase Errors ◽  
Power Series Expansions ◽  
Analytic Expressions ◽  
Optimal Values ◽  
The Stability ◽  
Stability And Accuracy ◽  
Total Model ◽  
Elastic Pendulum

Abstract Errors caused by discrete time stepping may be an important component of total model error in contemporary atmospheric and oceanic simulations. To reduce time-stepping errors in leapfrog integrations, the Robert–Asselin–Williams (RAW) filter was proposed by the author as a simple improvement to the widely used Robert–Asselin (RA) filter. The present paper examines the behavior of the RAW filter in semi-implicit integrations. First, in a linear theoretical analysis, the stability and accuracy are interrogated by deriving analytic expressions for the amplitude errors and phase errors. Then, power-series expansions are used to interpret the leading-order errors for small time steps and hence to identify optimal values of the filter parameters. Finally, the RAW filter is tested in a realistic nonlinear setting, by applying it to semi-implicit integrations of the elastic pendulum equations. The results suggest that replacing the RA filter with the RAW filter could reduce time-stepping errors in semi-implicit integrations.

scholarly journals The investigation of the coefficients of materials of hard hulls of autonomous deep-underwater vehicles

2018 ◽  
Vol 189 ◽  
pp. 01002
Author(s):  
Aleksandr Karpachev
Keyword(s):  
Aluminum Alloy ◽  
Modulus Of Elasticity ◽  
Critical Pressure ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Poisson Coefficient ◽  
New Type ◽  
Optimal Values ◽  
The Stability

The conceptional projecting of new type of marine technique presented by autonomous underwater vehicles based on new type of materials for hard hulls. As is known, the quality of the materials of hard hulls depends on the Poisson coefficient and the modulus of elasticity (Young), which play an important role in calculating the critical pressure for stability. The problem of finding the optimum values of these coefficients (the maximum of the critical pressure) is of great interest for the creation of ideal materials for the hard hulls of underwater vehicles. Such a problem must be solved in conjunction with the task of optimizing another coefficient - the material's fluidity module. In the Investigations it is very important to accurately calculate the critical pressure for the stability of the hard hulls of underwater vehicles. This method of exact calculation has been created and tested in practice for known materials: aluminum alloy, steel, titanium and fiberglass. The method was also used to solve the problem of creating a new type of material for hard hulls with optimal values of the yield coefficients, Jung and Poisson.

Planning of Dynamic Compensation Manipulator Motions for Stability Enhancement of Mobile Manipulators by Soft Computing

2006 ◽  
Author(s):  
Ali Ghaffari ◽  
Ali Meghdari ◽  
Davood Naderi ◽  
Sohrab Eslami
Keyword(s):  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Pd Controller ◽  
Robot System ◽  
End Effector ◽  
Compensatory Motion ◽  
Stability Issue ◽  
Optimal Values ◽  
The Stability ◽  
Stability Enhancement

Mobile manipulators are developed in order to execute separately in various regions where there is not possibility for human to appear there. Recently, the size of mobile manipulators has been decreased according to their given tasks. For such systems, the stability issue is very important. The robot system should be able to keep itself in an optimal situation. For reaching to this goal, one can use a redundant degree of freedom for the mobile manipulator such that this redundancy makes it possible to recover the system's stability by dynamic compensatory motion of manipulator when the system is unstable. In this paper, we present an algorithm which is fast enough to stabilize the mobile manipulator with the best stability criterion based on a neural network and genetic algorithm which cooperate together. For applying the optimal values as the algorithm outputs to the appropriate joints, a PD controller is used. The significance of this algorithm is provided for a spatial mobile manipulator with a predefined trajectory of the end-effector and the vehicle.

scholarly journals Stability Analysis of Steel Welded Tubes Forming Process Using Numerical Simulations

2021 ◽  
Vol 15 (2) ◽  
pp. 298-304
Author(s):  
Marko Delić ◽  
Vesna Mandić ◽  
Marko Popović
Keyword(s):  
Influencing Factors ◽  
Numerical Experiments ◽  
Hard Metal ◽  
Outer Diameter ◽  
Forming Process ◽  
Tube Forming ◽  
Welded Tube ◽  
Optimal Values ◽  
Geometrical Factors ◽  
The Stability

In this paper, the research results of the stability of steel welded tubes forming process are presented. The aim of this research is to determine influence of geometrical and tribological parameters on stability of the process and to determine optimal values of influential process parameters. A research plan with variation of influential parameters was made, on the basis of which experimental and numerical experiments were performed. Tube forming was performed in one operation in a two-part tool made of hard metal by a combination of widening and narrowing. The geometrical factors observed during experiments are length, outer diameter and thicknesses of steel welded tube as a billet. Friction conditions in contact between tool and tubular workpiece are considered in two cases, the first one when standard machine oil is used as a lubricant and the second one when tube billet surface is phosphated. Based on results of experiments, influencing factors on stability of tube forming process were analysed and optimal production technology was recommended, including optimal values of influencing factors. Results obtained by experimental research were confirmed through numerical experiments based on finite element method.

A Study of the Oil-Lubricated Herringbone-Grooved Journal Bearing—Part 1: Numerical Analysis

1996 ◽  
Vol 118 (4) ◽  
pp. 906-911 ◽  
Author(s):  
Kyungphil Kang ◽  
Yoonchul Rhim ◽  
Kiro Sung
Keyword(s):  
Journal Bearing ◽  
Numerical Study ◽  
Radial Force ◽  
Rectangular Profile ◽  
Governing Differential Equation ◽  
Optimal Values ◽  
The Stability ◽  
Stiffness And Damping ◽  
Optimal Configurations ◽  
Bearing Part

A numerical study of the oil-lubricated herringbone-grooved journal bearing is presented for the case of eight circular-profile grooves on the sleeve surface. The governing differential equation derived from the mass balance is solved by using the finite difference method. Some of the groove geometries are constrained because of the groove forming processes. Optimal values for various bearing parameters are obtained to maximize the radial force and to improve the stability characteristics. Results are compared with the plain and rectangular-profile grooved journal bearings. Radial force, attitude angle, stiffness and damping coefficients, and stability map are given for optimal configurations.

scholarly journals A Roadheader-Assisted Coal Cutter Based on Tensile Failure Mechanism of Coal

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Bo Liu ◽  
Zhiliu Wang ◽  
Wei Xu ◽  
Zhiwei Yu ◽  
Zhendong Yan ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Tensile Failure ◽  
Beam Model ◽  
Mining Method ◽  
Working Mechanism ◽  
Working Face ◽  
Mechanical Models ◽  
Mining Width ◽  
Optimal Values ◽  
The Stability

This paper proposes a new roadheader-assisted coal cutter (RACC) based on the tensile failure mechanism of coal. An innovative mining method, called the cutting inside and spalling outside mining (CISOM) method, is developed based on this new RACC. The mechanical model is established, and the working mechanism of the new CISOM method is illustrated using a column model and a beam model. The mechanical models reveal that the tensile stress causes greater deflection than compressive stress. The deflection and mining width demonstrates a quadratic relationship. To understand the stratum behaviors and improve mining efficiency, the stability of a working face owned by Jincheng Coal Mining Group in Shanxi is analyzed using UDEC numerical simulation. Numerical results indicate that the optimal values of the parameter are 0.8 m width for the inside cutting and 0.4 m width for the outside spalling at #1305 working face. The newly developed RACC was successfully applied at #1305 working face. The field results showed that the recovery rate of CISOM method is over 90%; i.e., it is improved by 20% in comparison with the traditional method.

Pretreatment of Trap Grease with Amberlyst-15 for Biodiesel Production

2011 ◽  
Vol 347-353 ◽  
pp. 2528-2531 ◽  
Author(s):  
Da Long Huang ◽  
Zhong Ming Wang ◽  
Zhen Hong Yuan
Keyword(s):  
Acid Value ◽  
Biodiesel Production ◽  
Orthogonal Experimental Design ◽  
Reaction Conditions ◽  
Amberlyst 15 ◽  
Trap Grease ◽  
Repeated Use ◽  
Optimal Values ◽  
The Stability ◽  
Optimal Reaction

After investigating the effects of each parameter on the esterification of FFA catalyzed by Amberlyst-15 in the trap grease, the optimal values were determined through an orthogonal experimental design. The optimum conditions for the esterification were determined to be 27:1 molar for the methanol to FFA in the trap grease, 95°C for the reaction temperature and 3 h for the reaction time. Stability of Amberlyst-15 was also studied under the optimal reaction conditions. The stability of the catalyst was not decreased much even after 10 times repeated use. The acid value was decreased from 100 mg KOH/g to 1.3 mg KOH/g in this process.

Open discussion

1982 ◽  
Vol 99 ◽  
pp. 605-613
Author(s):  
P. S. Conti
Keyword(s):  
Buenos Aires ◽  
Large Mass ◽  
List Type ◽  
Common Phenomenon ◽  
Open Discussion ◽  
The Stability ◽  
Ring Nebulae

Conti: One of the main conclusions of the Wolf-Rayet symposium in Buenos Aires was that Wolf-Rayet stars are evolutionary products of massive objects. Some questions:–Do hot helium-rich stars, that are not Wolf-Rayet stars, exist?–What about the stability of helium rich stars of large mass? We know a helium rich star of ∼40 MO. Has the stability something to do with the wind?–Ring nebulae and bubbles : this seems to be a much more common phenomenon than we thought of some years age.–What is the origin of the subtypes? This is important to find a possible matching of scenarios to subtypes.

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