Preface of the “Third Symposium on Engineering Problems of Plasticity”

2016 ◽  
Author(s):  
Rostislav I. Nepershin
Keyword(s):  
The Third ◽  
Engineering Problems

scholarly journals Three- dimensional numerical simulation analysis of the influence of structural parameters on the performance of air ejector

2021 ◽  
Vol 2045 (1) ◽  
pp. 012011
Author(s):  
L F Han ◽  
T J Liu ◽  
L Li ◽  
D Q Liu
Keyword(s):  
Numerical Simulation ◽  
Simulation Analysis ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Calculation Model ◽  
Optimal Combination ◽  
The Third ◽  
Engineering Problems ◽  
Complex Engineering ◽  
Air Ejector

Abstract Nowadays, CFD technology has become the third tool to study hydrodynamics problems after theoretical analysis and experimental research, especially in dealing with and solving complex engineering problems such as supersonic. In this paper, using the method of control variables, the system studied a type air ejector structure parameters within a certain range changes affect the performance of the work by means of FLUENT, at the same time, the optimal combination of the structural parameters are given, then three dimensional numerical simulation of the optimal combination model, and the simulation value and experiment value has carried on the contrast and analysis, Compared with the two-dimensional and axisymmetric model, Three-dimensional calculation model is more reliable and reasonable.

An Effective Dynamic Evolutionary Algorithm for Engineering Problems

2012 ◽  
Vol 542-543 ◽  
pp. 294-301
Author(s):  
Qing Zhang ◽  
San You Zeng ◽  
Hai Qing Ye ◽  
Zheng Jun Li ◽  
Hong Yong Jing
Keyword(s):  
Evolutionary Algorithms ◽  
State Of The Art ◽  
Global Search ◽  
Benchmark Problems ◽  
The Third ◽  
Dynamic Technique ◽  
Effective Dynamic ◽  
Engineering Problems ◽  
General Test ◽  
Better Than

A dynamic evolutionary algorithms (DEA) is designed to solve engineering problems in this paper. The DEA algorithm makes two differences. (1) Dynamic technique is used to handle equality constraints. (2) Two unrelated crossovers (linear crossover and uniform crossover) are combined in the algorithm for avoiding duplicate search and then helping global search. In solving engineering problems, three steps are taken: a DEA algorithm is designed first, then after tested by general benchmark problems, it is improved, and the third step is that the improved DEA algorithm is applied to solve engineering problems. The general test suggests our DEA algorithm outperforms the compared state-of-the-art other algorithms. The experimental results in solving 5 engineering problems indicate that our method works much better than the compared state-of-the-art algorithms, especially, in global search.

scholarly journals Relaxation methods applied to engineering problems. VII. Problems relating to the percolation of fluids through porous materials

1941 ◽  
Vol 178 (972) ◽  
pp. 1-17 ◽  
Keyword(s):  
Porous Materials ◽  
Velocity Potential ◽  
A Priori ◽  
Fluid Pressure ◽  
Relaxation Method ◽  
Sufficient Accuracy ◽  
Relaxation Methods ◽  
The Third ◽  
Fluid Field ◽  
Engineering Problems

The accepted theory of percolation of fluids through porous materials (which is based on Darcy’s law of resistance) indicates that the velocities can be calculated from a velocity-potential which, in two-dimensional motion, is plane-harmonic within the fluid field. The associated stream function, and the fluid pressure, are also plane-harmonic, so in cases where all boundaries are known their determination is an ordinary problem in plane-potential theory. But in cases where a free surface exists (as in the percolation of water through earth dams), its shape is not known a priori, consequently orthodox methods cannot be applied. Here the relaxation method developed in earlier papers is shown to be applicable without special assumptions, and to yield results of more than sufficient accuracy. Three typical examples are treated, the third involving ‘refraction’ of the lines of flow and pressure at the junction of two materials of different porosity.

scholarly journals The ‘ I 3 ’ generalization of the Galileo–Rankine tension criterion

2014 ◽  
Vol 470 (2172) ◽  
pp. 20140568 ◽  
Author(s):  
R. Lagioia ◽  
A. Panteghini ◽  
A. M. Puzrin
Keyword(s):  
Stress Tensor ◽  
Structural Engineering ◽  
Constitutive Models ◽  
Physical Significance ◽  
The Third ◽  
Third Invariant ◽  
Engineering Problems ◽  
Principal Stress Space ◽  
Rankine Criterion ◽  
New Criterion

The paper presents a new tension failure criterion which generalizes the so-called Galileo–Rankine formulation. The criterion can be used as a component of the so-called perfectly no-tension model for masonry and cements as well as for establishing a tension cut-off in complex constitutive models for soils, granular materials and powders. The criterion is described by means of a very concise equation based on the third invariant of the stress tensor, approximating the boundaries of the compressive octant of the principal stress space. This sheds new light on the physical significance of the third invariant of the stress tensor. The new criterion has been validated against two known analytical solutions for no-tension materials and also effectively applied for solving two geotechnical and structural engineering problems. The proposed formulation allows for an efficient implementation in finite-element programmes, removing some of the numerical difficulties associated with the Galileo–Rankine criterion.

scholarly journals New far-field extrapolation method for the computation of electric fields

2021 ◽  
Vol 51 (3) ◽  
Author(s):  
Xin Yang
Keyword(s):  
Electric Fields ◽  
Approximation Method ◽  
Time Domain ◽  
Far Field ◽  
Field Calculation ◽  
The Third ◽  
Scattering Field ◽  
Engineering Problems ◽  
Consistency Property ◽  
The Time Domain

The extrapolation of the electric field is studied theoretically both in frequency domain and time domain. Combining Gauss’s law with the approximation method in engineering, two new formulas for the scattering field calculation are derived from different logical ideas based on Stratton–Chu formula. The consistency property of the derived formulas is investigated, and the third formula for the scattering field calculation is further obtained. Finally, the time-domain extrapolation is discussed based on the formulas, followed by a simple numerical example. The results obtained are characterized by a simple form and intuitive physical meaning, and are helpful to calculate certain engineering problems.

Progress report on 21-cm observations at low latitude between longitudes (l 11) 0° and 66°

1967 ◽  
Vol 31 ◽  
pp. 177-179
Author(s):  
W. W. Shane
Keyword(s):  
Preliminary Report ◽  
Progress Report ◽  
Galactic Centre ◽  
Low Latitude ◽  
The Third ◽  
Introductory Lecture ◽  
Centre Region

In the course of several 21-cm observing programmes being carried out by the Leiden Observatory with the 25-meter telescope at Dwingeloo, a fairly complete, though inhomogeneous, survey of the regionl11= 0° to 66° at low galactic latitudes is becoming available. The essential data on this survey are presented in Table 1. Oort (1967) has given a preliminary report on the first and third investigations. The third is discussed briefly by Kerr in his introductory lecture on the galactic centre region (Paper 42). Burton (1966) has published provisional results of the fifth investigation, and I have discussed the sixth in Paper 19. All of the observations listed in the table have been completed, but we plan to extend investigation 3 to a much finer grid of positions.

The orbit of Pluto over a long interval of time

1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer
Keyword(s):  
Periodic Orbit ◽  
Numerical Integration ◽  
Restricted Problem ◽  
Three Dimensional ◽  
The Third ◽  
Circular Restricted Problem ◽  
Resonance Relation

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.

Monte Carlo Algorithms for Moments of Transition Arrays

1988 ◽  
Vol 102 ◽  
pp. 79-81
Author(s):  
A. Goldberg ◽  
S.D. Bloom
Keyword(s):  
Monte Carlo ◽  
State Vector ◽  
Basis Vector ◽  
Collective State ◽  
Dispersion Characteristics ◽  
Dipole Strength ◽  
The Third ◽  
Monte Carlo Algorithms ◽  
Third Moment ◽  
Very High

AbstractClosed expressions for the first, second, and (in some cases) the third moment of atomic transition arrays now exist. Recently a method has been developed for getting to very high moments (up to the 12th and beyond) in cases where a “collective” state-vector (i.e. a state-vector containing the entire electric dipole strength) can be created from each eigenstate in the parent configuration. Both of these approaches give exact results. Herein we describe astatistical(or Monte Carlo) approach which requires onlyonerepresentative state-vector |RV> for the entire parent manifold to get estimates of transition moments of high order. The representation is achieved through the random amplitudes associated with each basis vector making up |RV>. This also gives rise to the dispersion characterizing the method, which has been applied to a system (in the M shell) with≈250,000 lines where we have calculated up to the 5th moment. It turns out that the dispersion in the moments decreases with the size of the manifold, making its application to very big systems statistically advantageous. A discussion of the method and these dispersion characteristics will be presented.

Probe size and 5th-order aberration

1987 ◽  
Vol 45 ◽  
pp. 134-135 ◽  
Author(s):  
Zhifeng Shao
Keyword(s):  
Electron Probe ◽  
Spherical Aberration ◽  
Wave Length ◽  
Cylindrical Symmetry ◽  
Electron Wave ◽  
Third Order ◽  
The Third ◽  
Probe Radius ◽  
Small Probe ◽  
Probe Size

A small electron probe has many applications in many fields and in the case of the STEM, the probe size essentially determines the ultimate resolution. However, there are many difficulties in obtaining a very small probe.Spherical aberration is one of them and all existing probe forming systems have non-zero spherical aberration. The ultimate probe radius is given byδ = 0.43Csl/4ƛ3/4where ƛ is the electron wave length and it is apparent that δ decreases only slowly with decreasing Cs. Scherzer pointed out that the third order aberration coefficient always has the same sign regardless of the field distribution, provided only that the fields have cylindrical symmetry, are independent of time and no space charge is present. To overcome this problem, he proposed a corrector consisting of octupoles and quadrupoles.

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