31 resultados para Applications for positions.
Resumo:
Objective speckle from a stick-on foil is a new approach to applying the objective white light speckle method to in-plane displacement measurements. By a relatively easy technique a thin aluminum foil is mounted onto the specimen surface and a random grating is scratched onto it, yielding high reflectance and fine optical details. After double exposure by a direct recording system without using a lens, the resulting holographic film possesses a broad spatial spectrum and displacement information. Full-field contour maps of equal displacement can be obtained that are of good contrast and high sensitivity and that have a large adjustable measurement range. The method can be applied to practical engineering problems for both plane and developable curved surfaces.
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In this paper, we mainly deal with cigenvalue problems of non-self-adjoint operator. To begin with, the generalized Rayleigh variational principle, the idea of which was due to Morse and Feshbach, is examined in detail and proved more strictly in mathematics. Then, other three equivalent formulations of it are presented. While applying them to approximate calculation we find the condition under which the above variational method can be identified as the same with Galerkin's one. After that we illustrate the generalized variational principle by considering the hydrodynamic stability of plane Poiseuille flow and Bénard convection. Finally, the Rayleigh quotient method is extended to the cases of non-self-adjoint matrix in order to determine its strong eigenvalne in linear algebra.
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The optimization of off-null ellipsometry is described with emphasis on the improvement of resolution for visualizing biomolecule layers. For optical biosensor with layer thickness below 6.5 nm, a numerical simulation for the dependence of resolution on the azimuth settings of polarizer and analyzer is presented first. For comparison, three different resolutions are given at three azimuth settings which are near null and far away from null condition, respectively. Furthermore, the square or linear approximation relationship between the intensity and the layer thickness are also given at these settings. The difference among their accuracy is up to 100 times or so. Experimental results of the biosensor sample verify the optimization.
Resumo:
It is to investigate molecule interactions between antigen and antibody with ellipsometric imaging technique and demonstrate some features and possibilities offered by applications of the technique. Molecule interaction is an important interest for molecule biologist and immunologist. They have used some established methods such as immufluorcence, radioimmunoassay and surface plasma resonance, etc, to study the molecule interaction. At the same time, experimentalists hope to use some updated technique with more direct visual results. Ellipsometric imaging is non-destructive and exhibits a high sensitivity to phase transitions with thin layers. It is capable of imaging local variations in the optical properties such as thickness due to the presence of different surface concentration of molecule or different deposited molecules. If a molecular mono-layer (such as antigen) with bio-activity were deposited on a surface to form a sensing surface and then incubated in a solution with other molecules (such as antibody), a variation of the layer thickness when the molecules on the sensing surface reacted with the others in the solution could be observed with ellipsometric imaging. Every point on the surface was measured at the same time with a high sensitivity to distinguish the variation between mono-layer and molecular complexes. Ellipsometric imaging is based on conventional ellipsometry with charge coupled device (CCD) as detector and images are caught with computer with image processing technique. It has advantages of high sensitivity to thickness variation (resolution in the order of angstrom), big field of view (in square centimeter), high sampling speed (a picture taken within one second), and high lateral resolution (in the order of micrometer). Here it has just shown one application in study of antigen-antibody interaction, and it is possible to observe molecule interaction process with an in-situ technique.
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The MID-K, a new kind of multi-pipe string detection tool is introduced. This tool provides a means of evaluating the condition of in-place pipe string, such as tubing and casino. It is capable of discriminating the defects of the inside and outside, and estimating the thickness of tubing and casing. It is accomplished by means of a low frequency eddy current to detect flaws on the inner surface and a magnetic flux leakage to inspect the full thickness. The measurement principle, the technology and applications are presented in this paper.
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Table of Contents
1 | Introduction | 1 |
1.1 | What is an Adiabatic Shear Band? | 1 |
1.2 | The Importance of Adiabatic Shear Bands | 6 |
1.3 | Where Adiabatic Shear Bands Occur | 10 |
1.4 | Historical Aspects of Shear Bands | 11 |
1.5 | Adiabatic Shear Bands and Fracture Maps | 14 |
1.6 | Scope of the Book | 20 |
2 | Characteristic Aspects of Adiabatic Shear Bands | 24 |
2.1 | General Features | 24 |
2.2 | Deformed Bands | 27 |
2.3 | Transformed Bands | 28 |
2.4 | Variables Relevant to Adiabatic Shear Banding | 35 |
2.5 | Adiabatic Shear Bands in Non-Metals | 44 |
3 | Fracture and Damage Related to Adiabatic Shear Bands | 54 |
3.1 | Adiabatic Shear Band Induced Fracture | 54 |
3.2 | Microscopic Damage in Adiabatic Shear Bands | 57 |
3.3 | Metallurgical Implications | 69 |
3.4 | Effects of Stress State | 73 |
4 | Testing Methods | 76 |
4.1 | General Requirements and Remarks | 76 |
4.2 | Dynamic Torsion Tests | 80 |
4.3 | Dynamic Compression Tests | 91 |
4.4 | Contained Cylinder Tests | 95 |
4.5 | Transient Measurements | 98 |
5 | Constitutive Equations | 104 |
5.1 | Effect of Strain Rate on Stress-Strain Behaviour | 104 |
5.2 | Strain-Rate History Effects | 110 |
5.3 | Effect of Temperature on Stress-Strain Behaviour | 114 |
5.4 | Constitutive Equations for Non-Metals | 124 |
6 | Occurrence of Adiabatic Shear Bands | 125 |
6.1 | Empirical Criteria | 125 |
6.2 | One-Dimensional Equations and Linear Instability Analysis | 134 |
6.3 | Localization Analysis | 140 |
6.4 | Experimental Verification | 146 |
7 | Formation and Evolution of Shear Bands | 155 |
7.1 | Post-Instability Phenomena | 156 |
7.2 | Scaling and Approximations | 162 |
7.3 | Wave Trapping and Viscous Dissipation | 167 |
7.4 | The Intermediate Stage and the Formation of Adiabatic Shear Bands | 171 |
7.5 | Late Stage Behaviour and Post-Mortem Morphology | 179 |
7.6 | Adiabatic Shear Bands in Multi-Dimensional Stress States | 187 |
8 | Numerical Studies of Adiabatic Shear Bands | 194 |
8.1 | Objects, Problems and Techniques Involved in Numerical Simulations | 194 |
8.2 | One-Dimensional Simulation of Adiabatic Shear Banding | 199 |
8.3 | Simulation with Adaptive Finite Element Methods | 213 |
8.4 | Adiabatic Shear Bands in the Plane Strain Stress State | 218 |
9 | Selected Topics in Impact Dynamics | 229 |
9.1 | Planar Impact | 230 |
9.2 | Fragmentation | 237 |
9.3 | Penetration | 244 |
9.4 | Erosion | 255 |
9.5 | Ignition of Explosives | 261 |
9.6 | Explosive Welding | 268 |
10 | Selected Topics in Metalworking | 273 |
10.1 | Classification of Processes | 273 |
10.2 | Upsetting | 276 |
10.3 | Metalcutting | 286 |
10.4 | Blanking | 293 |
Appendices | 297 | |
A | Quick Reference | 298 |
B | Specific Heat and Thermal Conductivity | 301 |
C | Thermal Softening and Related Temperature Dependence | 312 |
D | Materials Showing Adiabatic Shear Bands | 335 |
E | Specification of Selected Materials Showing Adiabatic Shear Bands | 341 |
F | Conversion Factors | 357 |
References | 358 | |
Author Index | 369 | |
Subject Index | 375 |
Resumo:
In this paper, multi-hole cooling is studied for an oxide/oxide ceramic specimen with normal injection holes and for a SiC/SiC ceramic specimen with oblique injection holes. A special purpose heat transfer tunnel was designed and built, which can provide a wide range of Reynolds numbers (10(5)similar to 10(7)) and a large temperature ratio of the primary flow to the coolant (up to 2.5). Cooling effectiveness determined by the measured surface temperature for the two types of ceramic specimens is investigated. It is found that the multi-hole cooling system for both specimens has a high cooling efficiency and it is higher for the SiC/SiC specimen than for the oxide/oxide specimen. Effects on the cooling effectiveness of parameters including blowing ratio, Reynolds number and temperature ratio, are studied. In addition, profiles of the mean velocity and temperature above the cooling surface are measured to provide further understanding of the cooling process. Duplication of the key parameters for multi-hole cooling, for a representative combustor flow condition (without radiation effects), is achieved with parameter scaling and the results show the high efficiency of multi-hole cooling for the oblique hole, SiC/SiC specimen. (C) 2008 Elsevier Ltd. All rights reserved.
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In this paper, a new definition of SE and CE, which is based on the hexahedron mesh and simpler than Chang's original CE/SE method (the space-time Conservation Element and Solution Element method), is proposed and an improved CE/SE scheme is constructed. Furthermore, the improved CE/SE scheme is extended in order to solve the elastic-plastic flow problems. The hybrid particle level set method is used for tracing the interfaces of materials. Proper boundary conditions are presented in interface tracking. Two high-velocity impact problems are simulated numerically and the computational results are carefully compared with the experimental data, as well as the results from other literature and LS-DYNA software. The comparisons show that the computational scheme developed currently is clear in physical concept, easy to be implemented and high accurate and efficient for the problems considered. (C) 2008 Elsevier Ltd. All rights reserved.
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The new numerical algorithms in SUPER/CESE and their applications in explosion mechanics are studied. The researched algorithms and models include an improved CE/SE (space-time Conservation Element and Solution Element) method, a local hybrid particle level set method, three chemical reaction models and a two-fluid model. Problems of shock wave reflection over wedges, explosive welding, cellular structure of gaseous detonations and two-phase detonations in the gas-droplet system are simulated by using the above-mentioned algorithms and models. The numerical results reveal that the adopted algorithms have many advantages such as high numerical accuracy, wide application field and good compatibility. The numerical algorithms presented in this paper may be applied to the numerical research of explosion mechanics.
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In this paper, a new computational scheme for solving flows in porous media was proposed. The scheme was based on an improved CE/SE method (the space-time Conservation Element and Solution Element method). We described porous flows by adopting DFB (Brinkman-Forchheimer extended Darcy) equation. The comparison between our computational results and Ghia's confirmed the high accuracy, resolution, and efficiency of our CE/SE scheme. The proposed first-order CE/SE scheme is a new reliable way for numerical simulations of flows in porous media. After investigation of effects of Darcy number on porous flow, it shows that Darcy number has dominant influence on porous flow for the Reynolds number and porosity considered.
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Thermal cracking of China No.3 aviation kerosene was studied experimentally and analytically under supercritical conditions relevant to regenerative cooling system for Mach-6 scramjet applications. A two-stage heated tube system with cracked products collection/analysis was used and it can achieve a fuel temperature range of 700-1100 K, a pressure range of 3.5-4.5 MPa and a residence time of approximately 0.5-1.3 s. Compositions of the cracked gaseous products and mass flow rate of the kerosene flow at varied temperatures and pressures were obtained experimentally. A one-step lumped model was developed with the cracked mixtures grouped into three categories: unreacted kerosene, gaseous products and residuals including liquid products and carbon deposits. Based on the model, fuel conversion on the mass basis, the reaction rate and the residence time were estimated as functions of temperature. Meanwhile, a sonic nozzle was used for the control of the mass flow rate of the cracked kerosene, and correlation of the mass flow rate gives a good agreement with the measurements.
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The group velocities of the probe laser field are studied in a A-type system where one lower state has two fold levels coupled by a control field. It is found that the interaction of double dark states leads to controllable group velocity of the probe field in this system. It can be easily realized, due to the interacting double dark resonances, that one of the group velocities at transparency positions is much slower than the other by tuning the control field to be off resonance. In particular, when the control field is on resonance. we can obtain two equal slow group velocities with a broader EIT width, which provides potential applications in quantum storage and retrieval of light. (c) 2005 Elsevier B.V. All rights reserved.
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Plasma equilibrium geometry has a great influence on the confinement and magnetohydrodynamic stability in tokamaks. The poloidal field (PF) system of a tokamak should be optimized to support the prescribed plasma equilibrium geometry. In this paper, a genetic algorithm-based method is applied to solve the optimization of the positions and currents of tokamak PF coils. To achieve this goal, we first describe the free-boundary code EQT Based on the EQT code, a genetic algorithm-based method is introduced to the optimization. We apply this new method to the PF system design of the fusion-driven subcritical system and plasma equilibrium geometry optimization of the Experimental Advanced Superconducting Tokamak (EAST). The results indicate that the optimization of the plasma equilibrium geometry can be improved by using this method.
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The Talbot effect is one of the most basic optical phenomena that has received extensive investigations both because its new results provide us more understanding of the fundamental Fresnel diffraction and also because of its wide applications. We summarize our recent results on this subject. Symmetry of the Talbot effect, which was reported in Optics Communications in 1995, is now realized as the key to reveal other rules for explanation of the Talbot effect for array illumination. The regularly rearranged-neighboring-phase-differences (RRNPD) rule, a completely new set of analytic phase equations (Applied Optics, 1999), and the prime-number decomposing rule (Applied Optics, 2001) are the newly obtained results that reflect the symmetry of the Talbot effect in essence. We also reported our results on the applications of the Talbot effect. Talbot phase codes are the orthogonal codes that can be used for phase coding of holographic storage. A new optical scanner based on the phase codes for Talbot array illumination has unique advantages. Furthermore, a novel two-layered multifunctional computer-generated hologram based on the fractional Talbot effect was proposed and implemented (Optics Letters, 2003). We believe that these new results should bring us more new understanding of the Talbot effect and help us to design novel optical devices that should benefit practical applications. (C) 2004 Society of Photo-Optical Instrumentation Engineers.