An Interface Model to Predict the Stability of Landslide with Weak Intercalated Layer

To enhance the stability and accuracy of the digital-physical hybrid simulation system of a modular multilevel converter-based high voltage direct current (MMC-HVDC) system, this paper presents an improved power interface modeling algorithm based on ideal transformer method (ITM). By analyzing the stability condition of a hybrid simulation system based on the ITM model, the current of a so-called virtual resistance is added to the control signal of the controlled current source in the digital subsystem, and the stability of the hybrid simulation system with the improved power interface model is analyzed. The value of the virtual resistance is optimized by comprehensively considering system stability and simulation precision. A two-terminal bipolar MMC-HVDC simulation system based on the proposed power interface model is established. The comparisons of the simulation results verify that the proposed method can effectively improve the stability of the hybrid simulation system, and at the same time has the advantages of high simulation accuracy and easy implementation.

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Stability and Deformation Analysis for Excavation and Backfilling of Fushun West Open-Pit Coal Mine

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.353-356.751 ◽

2013 ◽

Vol 353-356 ◽

pp. 751-755 ◽

Cited By ~ 1

Author(s):

Yong Cheng Yan ◽

Xian Zhang Ling ◽

Feng Zhang ◽

Jia Hui Wang

Keyword(s):

Coal Mine ◽

Slip Surface ◽

Surrounding Rock ◽

Open Pit ◽

Deformation Analysis ◽

Interface Model ◽

Safety Coefficient ◽

Mine Slope ◽

The Stability ◽

Technical Basis

Taking section W400 of Fushun west open-pit coal mine for the research, the interface model of fracture zone and surrounding rock was established. FLAC3D is used to analysis the influence of excavation and backfill of open-fit coal mine to the slope stability and deformation. The numerical results and analysis show that: (1) when the open-pit coal mine slope is excavated to final production line, the safety coefficient is 2.98, with the excavation, the deformation of the Fushun No.1 Refinery Factory area increases. (2) With the increase of backfilling, the slope coefficient increases to 3.32, this will reduce the deformation of the Fushun No.1 Refinery Factory area. Furthermore, the positions of the dangerous slip surface and serious deformation part of factory area should be regards as key areas. These conclusions could provide technical basis for the stability analysis of Fushun west open-pit coal mine.

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Stability Analysis Method for Rock Slope with an Irregular Shear Plane Based on Interface Model

Advances in Civil Engineering ◽

10.1155/2018/8190908 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Changqing Qi ◽

Jiabing Qi ◽

Liuyang Li ◽

Jin Liu

Keyword(s):

Stability Analysis ◽

Slope Failure ◽

Rock Slope ◽

Limit Equilibrium ◽

Shear Plane ◽

Interface Model ◽

Analysis Method ◽

Complex Shear ◽

Potential Failure ◽

The Stability

Landslide developed in rock mass usually has irregular shear plane. An approach for calculating distributed factor of safety of the irregular shear plane was put forward in this paper. The presented method can obtain not only the detailed stability status at any grid node of a complex shear plane but also the global safety of the slope. Thus, it is helpful to thoroughly understand the mechanism of slope failure. Comparing with the result obtained through the limit equilibrium method, the presented method was proved to be more accurate and suitable for stability analysis of rock slope with a thin shear plane. The stability of a potentially unstable rock slope was analyzed based on the presented method at the end of this paper. The detailed local stability, global stability, and the potential failure mechanism were provided.

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On Physical Mechanisms of Mushy Zone Formation in Solidification of Pure Semitransparent Materials

10.1115/imece1999-1039 ◽

1999 ◽

Author(s):

G.-X. Wang ◽

Chengcai Yao ◽

B. T. F. Chung

Keyword(s):

Mushy Zone ◽

Local Equilibrium ◽

Planar Interface ◽

Zone Model ◽

Interface Model ◽

Zone Formation ◽

Physical Mechanisms ◽

The Stability ◽

Solid Liquid Interface ◽

Non Equilibrium

Abstract Two different models, the isothermal mushy zone model and the non-equilibrium planar interface model, are employed to solve the solidification problem of a one-dimensional semitransparent slab subject to radiative and convective cooling at the surface. The mushy zone model is based on the assumption of local equilibrium and predicts the formation of a mushy zone as soon as the temperature of the slab surface reaches the equilibrium melting temperature. The non-equilibrium planar interface model, on the other hand, assumes a stable planar solid/liquid interface during solidification. It allows the existence of melt undercooling at the interface and in the bulk melt. The stability of the planar interface is then examined approximately using the linear stability criterion derived for an opaque material. It is found that a planar interface would be stable even if a large undercooling is generated in the bulk melt in front of the interface. If the rate of external heat transfer is small, however, the planar interface will break down and develop into thermal cells or dendrites. In addition, a transition from a mushy zone to a planar interface is also observed. Based on these results, the thermodynamics and kinetics of crystalline nucleation and growth are examined to illustrate the physical mechanisms of mushy zone formation during solidification of a semi transparent material. It is suggested that the isothermal mushy model and the planar interface model are valid only under corresponding processing conditions, and more research is needed to provide a complete description of the process.

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Co-Simulation of Multibody Systems With Contact Using Reduced Interface Models

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4046052 ◽

2020 ◽

Vol 15 (4) ◽

Cited By ~ 1

Author(s):

Albert Peiret ◽

Francisco González ◽

József Kövecses ◽

Marek Teichmann

Keyword(s):

Integration Step ◽

Interface Model ◽

Stick Slip ◽

Interface Models ◽

Simulation Techniques ◽

Coupling Variables ◽

Mixed Linear Complementarity Problem ◽

The Stability ◽

Unilateral Contact And Friction ◽

Reduced Representations

Abstract Co-simulation techniques enable the coupling of physically diverse subsystems in an efficient and modular way. Communication between subsystems takes place at discrete-time instants and is limited to a given set of coupling variables, while the internals of each subsystem remain undisclosed and are generally not accessible to the rest of the simulation environment. In noniterative co-simulation schemes, commonly used in real-time applications, this may lead to the instability of the numerical integration. The stability of the integration in these cases can be enhanced using interface models, i.e., reduced representations of one or more subsystems that provide physically meaningful input values to the other subsystems between communication points. This work describes such an interface model that can be used to represent nonsmooth mechanical systems subjected to unilateral contact and friction. The dynamics of the system is initially formulated as a mixed linear complementarity problem (MLCP), from which the effective mass and force terms of the interface model are derived. These terms account for contact detachment and stick–slip transitions, and can also include constraint regularization in case of redundancy in the system. The performance of the proposed model is shown in several challenging examples of noniterative multirate co-simulation schemes of a mechanical system with hydraulic components, which feature faster dynamics than the multibody subsystem. Using an interface model improves simulation stability and allows for larger integration step-sizes, thus resulting in a more efficient simulation.

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Open discussion

Symposium - International Astronomical Union ◽

10.1017/s0074180900029533 ◽

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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Symmetric Multistep Methods Revisited: II. Numerical Experiments

International Astronomical Union Colloquium ◽

10.1017/s0252921100031602 ◽

1999 ◽

Vol 173 ◽

pp. 309-314 ◽

Cited By ~ 3

Author(s):

T. Fukushima

Keyword(s):

Multistep Methods ◽

Computational Time ◽

Integration Time ◽

Implicit Methods ◽

Symmetric Methods ◽

Celestial Bodies ◽

The Stability ◽

Predictor Corrector ◽

Symmetric Multistep Methods ◽

Integration Errors

AbstractBy using the stability condition and general formulas developed by Fukushima (1998 = Paper I) we discovered that, just as in the case of the explicit symmetric multistep methods (Quinlan and Tremaine, 1990), when integrating orbital motions of celestial bodies, the implicit symmetric multistep methods used in the predictor-corrector manner lead to integration errors in position which grow linearly with the integration time if the stepsizes adopted are sufficiently small and if the number of corrections is sufficiently large, say two or three. We confirmed also that the symmetric methods (explicit or implicit) would produce the stepsize-dependent instabilities/resonances, which was discovered by A. Toomre in 1991 and confirmed by G.D. Quinlan for some high order explicit methods. Although the implicit methods require twice or more computational time for the same stepsize than the explicit symmetric ones do, they seem to be preferable since they reduce these undesirable features significantly.

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Uniformity of Magnification from Different Electron Microscopes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060179 ◽

1967 ◽

Vol 25 ◽

pp. 32-33

Author(s):

Godfrey C. Hoskins ◽

V. Williams ◽

V. Allison

Keyword(s):

Diffraction Grating ◽

The Other ◽

Carbon Replica ◽

Electron Microscopes ◽

The Stability

The method demonstrated is an adaptation of a proven procedure for accurately determining the magnification of light photomicrographs. Because of the stability of modern electrical lenses, the method is shown to be directly applicable for providing precise reproducibility of magnification in various models of electron microscopes.A readily recognizable area of a carbon replica of a crossed-line diffraction grating is used as a standard. The same area of the standard was photographed in Phillips EM 200, Hitachi HU-11B2, and RCA EMU 3F electron microscopes at taps representative of the range of magnification of each. Negatives from one microscope were selected as guides and printed at convenient magnifications; then negatives from each of the other microscopes were projected to register with these prints. By deferring measurement to the print rather than comparing negatives, correspondence of magnification of the specimen in the three microscopes could be brought to within 2%.

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Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069211 ◽

1970 ◽

Vol 28 ◽

pp. 444-445

Author(s):

E. R. Kimmel ◽

H. L. Anthony ◽

W. Scheithauer

Keyword(s):

High Temperature ◽

Metal Matrix ◽

Oxide Particle ◽

Oxide Phase ◽

Dislocation Motion ◽

Particle Dispersion ◽

High Temperature Strength ◽

Strengthening Effect ◽

Oxide Particles ◽

The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

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