scholarly journals Determination of Prestress in Circular Inhomogeneous Solid and Annular Plates in the Framework of the Timoshenko Hypotheses

2021 ◽  
Vol 11 (21) ◽  
pp. 9819
Author(s):  
Ivan V. Bogachev
Keyword(s):  
Inverse Problems ◽  
Distribution Patterns ◽  
Frequency Characteristics ◽  
Bending Vibrations ◽  
Annular Plates ◽  
Operational Characteristics ◽  
Projection Approach ◽  
Direct Problems ◽  
Timoshenko Hypotheses

Determination of prestress fields in structures is of the utmost importance, since they have a significant impact on operational characteristics, and their level and distribution must be strictly controlled. In this paper, we present modeling of bending vibrations of solid and annular round inhomogeneous prestressed plates within the framework of the Timoshenko hypotheses. New inverse problems of prestress identification in plates are studied on the basis of the acoustic response subjected to some probing load. To solve direct problems on calculating oscillations and amplitude-frequency characteristics, a computational Galerkin-method-based scheme has been developed. In order to treat the inverse problems, we use a special projection approach based on the constructed weak problems statements, which makes it possible to determine the desired characteristics in the given classes of functions. The developed techniques for solving direct problems are implemented in the form of software packages realized via Maple. For both solid and annular plates, we estimate the sensitivity of the amplitude-frequency characteristics the values of which are used as the additional data in the inverse problems to a change in the prestress level; we conclude that the most favorable frequency range should be selected in the resonance vicinity. We have conducted a series of computational tests on reconstructing the plate’s prestresses of various levels and distribution patterns (decreasing, increasing, sign-changing laws). The results of computational tests revealed that the technique developed allows for the determination of the prestresses with a low error for two cases: when the cause of prestress formation and its type are known and when arbitrary prestress changing laws are considered.

Development of an Optimization Framework for Parameter Identification and Shape Optimization Problems in Engineering

2011 ◽  
Vol 1 (1) ◽  
pp. 57-79 ◽  
Author(s):  
A. Andrade-Campos
Keyword(s):  
Inverse Problems ◽  
Shape Optimization ◽  
Parameter Identification ◽  
Optimization Problems ◽  
Optimization Methods ◽  
Optimum Shape ◽  
Optimization Framework ◽  
Search Optimization ◽  
Initial Geometry

The use of optimization methods in engineering is increasing. Process and product optimization, inverse problems, shape optimization, and topology optimization are frequent problems both in industry and science communities. In this paper, an optimization framework for engineering inverse problems such as the parameter identification and the shape optimization problems is presented. It inherits the large experience gain in such problems by the SiDoLo code and adds the latest developments in direct search optimization algorithms. User subroutines in Sdl allow the program to be customized for particular applications. Several applications in parameter identification and shape optimization topics using Sdl Lab are presented. The use of commercial and non-commercial (in-house) Finite Element Method codes to evaluate the objective function can be achieved using the interfaces pre-developed in Sdl Lab. The shape optimization problem of the determination of the initial geometry of a blank on a deep drawing square cup problem is analysed and discussed. The main goal of this problem is to determine the optimum shape of the initial blank in order to save latter trimming operations and costs.

Research of the Mechanism of Destruction of Compression Molds for Casting under Pressure of Color Alloys

2018 ◽  
Vol 284 ◽  
pp. 326-331 ◽  
Author(s):  
R.V. Gavariev ◽  
I.A. Savin
Keyword(s):  
Vapour Deposition ◽  
Optimum Structure ◽  
Pilot Studies ◽  
Method Of Calculation ◽  
Operational Characteristics ◽  
Building Surfaces

In the article various approaches to a research of the mechanism of destruction of form-building surfaces of compression molds for the casting under pressure (CUP) are considered. The main reasons for emergence of various defects of working surfaces of form-building details are defined. Method of calculation of the parameters allowing to define operability of concrete products are specified. The option of production of form-building surfaces with the raised operational characteristics drawing sheetings by method of phisical vapour deposition (PVD). is offered. Results of pilot studies on determination of optimum structure of a covering for a form-building surface are given.

An Improved Periodic Acid Fuchsin Sulfite Staining Method for Evaluation of Glycoproteins

1958 ◽  
Vol 4 (6) ◽  
pp. 476-483 ◽  
Author(s):  
Warren F McGuckin ◽  
Bernard F McKenzie
Keyword(s):  
Hydrochloric Acid ◽  
Periodic Acid ◽  
Distribution Patterns ◽  
Paper Electrophoresis ◽  
Acid Control ◽  
Chemical Determination ◽  
Disease Entities ◽  
The Individual

Abstract Modification of the Köiw and Grönwall procedure for the staining of glycoproteins separated by paper electrophoresis has adapted this method to papers of the Whatman 3MM class, with achievement of results comparable to those reported by direct chemical determination of hexose in the individual protein fractions. Preliminary concentration of specimen fluids was achieved by ultrafiltration through collodion sacks. A preliminary wash of the oven-dried paper strips with 95 per cent ethanol was found essential to clear the paper of buffer salts and insure that the pH in the oxidation procedure remained in the 3.0-3.5 range. Close control of the reagent composition and timing of each step were found necessary. Inclusion of 40 per cent ethanol in the oxidation bath and immersion of dry strips were required to insure rapid penetration of the periodic acid. Control of the oxidation procedure at 20 ± 0.5° for 12 minutes was of prime necessity to maintain a low background color. Also, the concentrations of hydrochloric acid in the dye bath and in the wash solutions were found to affect the quality of the final stain. The ethanol wash served to remove residual sulfite and hydrochloric acid and stabilize the color. The new method has been applied to the analysis of several body fluids of normal persons and patients with certain disease entities, and satisfactory glycoprotein distribution patterns have been obtained.

Automated Determination of Protein-Nitrogen in Cereals and Grains

1977 ◽  
Vol 60 (6) ◽  
pp. 1238-1242
Author(s):  
Robert N Revesz ◽  
Norman Aker
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Organic Material ◽  
Combustion Products ◽  
Direct Reading ◽  
Protein Nitrogen ◽  
Operational Characteristics ◽  
Temperature Sample ◽  
Automated Determination

Abstract This paper presents the design, performance, and operational characteristics of a new direct reading instrument for determining nitrogen in cereal and grain. Precision, accuracy, range, speed, ease of operation, sensitivity, sample size, and flexibility of the instrument are presented. Results on various cereals and grains are presented and compared with those obtained by the Kjeldahl technique. The apparatus is the result of research for a rapid method for determining nitrogen in organic material. The instrument uses a combination of a unique high temperature sample oxidation, a sampling valve for separating combustion products, and thermal conductivity detection for the liberated nitrogen in a helium carrier gas.

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