Researches concerning the Aerodynamic Sorting of Solid Particles According to the Surface States

2008 ◽  
Vol 59 (3) ◽  
pp. 360-365 ◽  
Author(s):  
Valentin Nedeff ◽  
Emilian Mosnegutu ◽  
Mirela Panainte ◽  
Carment Savin ◽  
Bogdan Macarescu
Keyword(s):  
Binary Mixture ◽  
Rough Surface ◽  
Surface State ◽  
Smooth Surface ◽  
Surface Condition ◽  
Surface States ◽  
Aerodynamic Characteristics ◽  
Solid Particles ◽  
Separation Degree ◽  
Sorting Process

The process of aerodynamic sorting of a solid particles mixture is influenced by the aerodynamic characteristics of the particles (shape, dimensions, the surface state and the density of the particle), which determine the behaviour of particles in the air flows. In this study it was analyzed the influence of the surface state of solid particles on the separation degree of a binary mixture, made from particles with smooth surface and particles with rough surface, submitted to the aerodynamic sorting. The correlation between the surface state of solid particles and their behavior in air flow is emphasized by the weight mass of the particles deposited in the collection boxes. It was observed that the particles with the smooth surface have higher floating velocities than the particles with the rough surface for closed dimensions, shapes and densities. The sorting process is influenced by the surface condition of the particle.

scholarly journals Road Surface State Recognition Based on SVM Optimization and Image Segmentation Processing

2017 ◽  
Vol 2017 ◽  
pp. 1-21 ◽  
Author(s):  
Jiandong Zhao ◽  
Hongqiang Wu ◽  
Liangliang Chen
Keyword(s):  
Image Segmentation ◽  
Surface State ◽  
Traffic Accidents ◽  
Surface Condition ◽  
Surface States ◽  
Road Surface ◽  
Support Vector ◽  
Image Size ◽  
State Recognition ◽  
Penalty Factor

Adverse road condition is the main cause of traffic accidents. Road surface condition recognition based on video image has become a central issue. However, hybrid road surface and road surface under different lighting environments are two crucial problems. In this paper, the road surface states are categorized into 5 types including dry, wet, snow, ice, and water. Then, according to the original image size, images are segmented; 9-dimensional color eigenvectors and 4 texture eigenvectors are extracted to construct road surface state characteristics database. Next, a recognition method of road surface state based on SVM (Support Vector Machine) is proposed. In order to improve the recognition accuracy and the universality, a grid searching algorithm and PSO (Particle Swarm Optimization) algorithm are used to optimize the kernel function factor and penalty factor of SVM. Finally, a large number of actual road surface images in different environments are tested. The results show that the method based on SVM and image segmentation is feasible. The accuracy of PSO algorithm is more than 90%, which effectively solves the problem of road surface state recognition under the condition of hybrid or different video scenes.

Surface Condition in the Plasma-CVD of a-Si:H,F from SiF4 and H2

1988 ◽  
Vol 131 ◽  
Author(s):  
A. Maruyama ◽  
D. S. Shen ◽  
V. Chu ◽  
J. Z. Liu ◽  
J. Jaroker ◽  
...  
Keyword(s):  
Surface State ◽  
Growth Temperature ◽  
Urbach Energy ◽  
Film Growth ◽  
Surface Condition ◽  
Surface States ◽  
State Density ◽  
Growth Surface ◽  
Plasma Cvd ◽  
Band Tail

ABSTRACTWe present a detailed study of the growth of a-Si:H,F from SiF4 and H4. The growth surface appears to have a high density of surface states. These surface states can be thermally relaxed by keeping the films at growth temperature after the termination of growth, suggesting that the states were created during film growth. When frozen in, the surface state density is found to depend on the conditions during film growth. The density is related to the sharpness of the valence band tail as measured by the Urbach Energy. We believe that a reaction on the growth surface resulting in fluorine elimination creates these surface states and also affects the formation of the Si-network.

Effective boundary conditions for Stokes flow over a rough surface

1996 ◽  
Vol 316 ◽  
pp. 223-240 ◽  
Author(s):  
Kausik Sarkar ◽  
Andrea Prosperetti
Keyword(s):  
Rough Surface ◽  
Stokes Flow ◽  
Smooth Surface ◽  
Traction Force ◽  
Slip Condition ◽  
Partial Slip ◽  
Ensemble Averaging ◽  
Effective Boundary ◽  
Exact Boundary ◽  
Effective Boundary Conditions

Ensemble averaging combined with multiple scattering ideas is applied to the Stokes flow over a stochastic rough surface. The surface roughness is modelled by compact protrusions on an underlying smooth surface. It is established that the effect of the roughness on the flow far from the boundary may be represented by replacing the no-slip condition on the exact boundary by a partial slip condition on the smooth surface. An approximate analysis is presented for a sparse distribution of arbitrarily shaped protrusions and explicit numerical results are given for hemispheres. Analogous conclusions for the two-dimensional case are obtained. It is shown that in certain cases a traction force develops on the surface at an angle with the direction of the flow.

Properties of Surface States on GaN and Related Compounds and Their Passivation by Dielectric Films

2002 ◽  
Vol 743 ◽  
Author(s):  
Hideki Hasegawa ◽  
Tamotsu Hashizume
Keyword(s):  
Plasma Treatment ◽  
Surface State ◽  
Surface Passivation ◽  
Hydrogen Plasma ◽  
Surface States ◽  
Ex Situ ◽  
Near Surface ◽  
Ecr Plasma ◽  
Good Surface ◽  
Donor States

ABSTRACTThis paper reviews the authors′ recent efforts to clarify the properties of electronic states near surfaces of GaN and AlGaN by using variousin-situandex-situcharacterization techniques, including UHV contact-less C-V, photoluminescence surface state spectroscopy (PLS3), cathode luminescence in-depth spectroscopy (CLIS),and gateless FET techniques that have been developed by the authors’ group.As a result, a model including a U-shaped surface state continuum, having a particular charge neutrality level, combined with frequent appearance of near-surface N-vacancy related deep donor states having a discrete level at Ec - 0.37eV is proposed as a unified model that can explain large gate leakage currents and current collapse in AlGaN/GaN HFETs. Hydrogen plasma treatment and SiO2deposition increase N-vacancy related deep donors. Reasonably good surface passivation can be achieved by ECR-plasma SiNx films and by ECR-plasma oxidized Al2O3films both combined with ECR N2plasma treatment.

Effects of Friction on Contact of Transverse Ground Surfaces

1994 ◽  
Vol 116 (3) ◽  
pp. 430-437 ◽  
Author(s):  
J. B. Mann ◽  
T. N. Farris ◽  
S. Chandrasekar
Keyword(s):  
Rough Surface ◽  
Contact Pressure ◽  
Smooth Surface ◽  
Bulk Material ◽  
Elastic Half Space ◽  
Material Surface ◽  
Asperity Contact ◽  
Hertz Contact ◽  
Effective Stresses ◽  
Subsurface Stress

The two-dimensional plane-strain sliding contact of a smooth rigid roller on a transverse ground rough surface is analyzed. The rough surface is idealized as an elastic half-space with periodic roughness modeled as cylindrical ridges oriented transverse to the sliding direction. The contact problem is solved using a numerical iterative method in which each asperity contact is treated as a micro-Hertz contact, and the exact treatment of asperity interaction is included. The subsurface stress field is calculated using Westergaard stress functions. The subsequent analysis compares the rough surface stress fields with the corresponding smooth Hertz contact to evaluate the influence of surface roughness and friction on the subsurface stress distributions. The results show that the real area of contact is less than the corresponding smooth surface Hertz contact area, and the magnitude of the actual localized maximum contact pressure is always greater than the corresponding smooth surface contact pressure. The asperity level subsurface effective stresses are greater in magnitude than the maximum subsurface stress due to the macro-Hertz contact for low coefficients of friction, and for high coefficients of friction the maximum effective stresses occur on the bulk material surface.

scholarly journals Termination switching of antiferromagnetic proximity effect in topological insulator

2020 ◽  
Vol 6 (33) ◽  
pp. eaaz8463
Author(s):  
Chao-Yao Yang ◽  
Lei Pan ◽  
Alexander J. Grutter ◽  
Haiying Wang ◽  
Xiaoyu Che ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Topological Insulator ◽  
Surface State ◽  
Proximity Effect ◽  
Surface States ◽  
Double Exchange ◽  
Exchange Interactions ◽  
Stacking Order ◽  
Bst Films ◽  
Magnetic Proximity Effect

This work reports the ferromagnetism of topological insulator, (Bi,Sb)2Te3 (BST), with a Curie temperature of approximately 120 K induced by magnetic proximity effect (MPE) of an antiferromagnetic CrSe. The MPE was shown to be highly dependent on the stacking order of the heterostructure, as well as the interface symmetry: Growing CrSe on top of BST results in induced ferromagnetism, while growing BST on CrSe yielded no evidence of an MPE. Cr-termination in the former case leads to double-exchange interactions between Cr3+ surface states and Cr2+ bulk states. This Cr3+-Cr2+ exchange stabilizes the ferromagnetic order localized at the interface and magnetically polarizes the BST Sb band. In contrast, Se-termination at the CrSe/BST interface yields no detectable MPE. These results directly confirm the MPE in BST films and provide critical insights into the sensitivity of the surface state.

Effect of Aramid Fiber Surface State on Properties of Epoxy Resin Composites

2019 ◽  
Vol 960 ◽  
pp. 167-173
Author(s):  
Man Shi Qiu ◽  
Ze Hua Pan ◽  
Yuan Yuan Zhang ◽  
Yong Lan Li ◽  
Nai Kui Gao ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Epoxy Resin ◽  
Surface State ◽  
Coupling Agent ◽  
Surface States ◽  
Aramid Fiber ◽  
Breakdown Field ◽  
Strength Increase ◽  
Resin Composites ◽  
Epoxy Resin Composites

The surface state of aramid fiber was modified by coupling agent to characterize the change of the state. The fiber / epoxy resin composites were prepared to study the mechanical and electrical properties and the internal mechanism of how different surface states affect. The results show that, after the treatment with the coupling agent, the surface roughness of the aramid fiber is increased，and the content of Si on the surface reach 5.8%, thus the surface activity is enhanced. At the same time, the treatment makes the properties of composites further improved. When the filling amount of aramid fiber reaches 30 strands, the tensile strength increase by 38.4% due to the coupling agent. In the test of two-layer samples, the breakdown field strength of the composites before and after treatment with coupling agent increased by 15.9% and 20.2%, respectively.Key words: aramid fiber; coupling agent; surface state; mechanical properties; electrical properties

Freeze-Thawing Damage Model of New-to-Old Concrete with Different Rough Interfaces

2013 ◽  
Vol 405-408 ◽  
pp. 2707-2714 ◽  
Author(s):  
Cheng Yi ◽  
Su Ling Lai ◽  
Hong Guang Zhu ◽  
Shi Hong Yan ◽  
Jian Xia Liu ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Rough Surface ◽  
Smooth Surface ◽  
Substrate Surface ◽  
Damage Model ◽  
Test Results ◽  
Two Stage ◽  
Second Stage ◽  
Rough Substrate ◽  
Substrate Surfaces

New-to-old concrete freeze-thawing durability affects the safety and normal service of structure. In this paper, the freeze-thawing resistance of new-to-old concrete with different rough substrate surfaces was studied. The roughness of substrate surface was characterized by fractal dimension. Test results show that freeze-thawing damage of new-to-old concrete has two stage changes: first stage, freeze-thawing damage increases rapidly, mainly caused by the damage of interface; second stage, freeze-thawing damage increases slower, mainly reflects damage of substrate and overlay. Compared with smooth surface, rough surface can significantly improve freeze-thawing resistance of new-to-old concrete. In a certain range, with the increase of fractal dimension, the freeze-thawing resistance improves. When the fractal dimension is beyond the range, the freeze-thawing resistance impairs while the fractal dimension increases. A freeze-thawing damage model applied to new-to-old concrete is proposed, and a good correlation is found between the model and experimental results.

Effect of Surface Roughness on Nanocontact: Quasicontinuum Simulation

2012 ◽  
Vol 502 ◽  
pp. 342-347 ◽  
Author(s):  
Wu Gui Jiang ◽  
Zheng Wei Wang
Keyword(s):  
Rough Surface ◽  
Smooth Surface ◽  
Characteristic Size ◽  
Contact Forces ◽  
Atomic Scale ◽  
Quasicontinuum Method ◽  
Cu Substrate ◽  
Nonlinear Fashion ◽  
Effect Of Surface ◽  
Good Agreement

By using the two-dimensional quasicontinuum method, the nanocontact between Ni indenter and single crystal Cu substrate with a smooth or rough surface is simulated. The contact force varies in a nonlinear fashion with the increasing indenter displacement, including several force drops. The atomic-scale deformation mechanism in the Cu substrate during nanocontact process is monitored. Shockley partials, Lomer-Cottrel locks as well as twinning faults are observed at the force drops. The Lomer-Cottrel locks play an important role in smooth surface nanocontact process, and they insure that Cu substrate undergoes elastic deformation dominantly during nanocontact process. The contact forces calculated from the Maugis-Dugale (M-D) theory show a good agreement with those obtained by the QC simulation in the smooth surface nanocontact process. It must be noted that the M-D theory is no longer suitable to describe the rough surface nanocontact problem due to the severe plastic deformation in the asperities of the substrate when the characteristic size of roughness is on the order of the indenter depth.

Finite Element Analysis on Real Contact Area Based on Fractal Characterization

2013 ◽  
Vol 579-580 ◽  
pp. 517-522 ◽  
Author(s):  
Jia Chun Wang ◽  
Bo Qiang Xing ◽  
Teng Zhao
Keyword(s):  
Finite Element ◽  
Rough Surface ◽  
Contact Area ◽  
Smooth Surface ◽  
Thermal Conductance ◽  
Element Model ◽  
Real Contact Area ◽  
Process Data ◽  
Element Analysis ◽  
Real Contact

No surface in engineering is absolutely smooth. It is important to analyze and calculate the real contact area for a better understanding of friction, wear, lubrication and thermal conductance. To obtain the accurate real contact area between rough surface and smooth surface, a rough-non-rigid-smooth surface contact finite element model is proposed in which the rough surface is characterized by fracture theory. In finite element modeling and analyzing process, MATLABEXCEL and AutoCAD are used to process data, and the smooth surface is considered to be non-rigid body. Compared with the traditional modeling, this method can obtain data quickly and is closer to the actual situation.

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