利用普通液晶显示屏显示光指针的一种方法

为了减少开发专用液晶显示屏这一环节,而利用PIC单片机来实现在普通的显示屏上同步显示光指针和数字量的一种方法。

Influence of pavement frictional properties on braking distance

In order to study the relationship between pavement friction management criteria and braking distance requirements of road geometric design, an approach for determining the braking distance considering pavement frictional properties is proposed. A finite element model （FEM） of a rolling tire under steady state is established based on theoretical hydrodynamics and mechanics principles, in which factors, including tire type, water film thickness, pavement surface properties, and vehicle speed, are considered. With the FEM, braking distances under different operating conditions are calculated. Furthermore, the allowable water film thickness is determined by comparing braking distances calculated with friction management criteria and that required by road geometric design. The results show that the braking distance is affected by the above operating conditions. As a result, it is necessary to maintain consistency between geometric design braking distance requirements and pavement friction management to achieve safe road operations.

Application of the double absorbing boundary condition in seismic modeling

We apply the newly proposed double absorbing boundary condition（DABC）（Hagstrom et al., 2014） to solve the boundary reflection problem in seismic finite-difference（FD） modeling. In the DABC scheme, the local high-order absorbing boundary condition is used on two parallel artificial boundaries, and thus double absorption is achieved. Using the general 2D acoustic wave propagation equations as an example, we use the DABC in seismic FD modeling, and discuss the derivation and implementation steps in detail. Compared with the perfectly matched layer（PML）, the complexity decreases, and the stability and fl exibility improve. A homogeneous model and the SEG salt model are selected for numerical experiments. The results show that absorption using the DABC is considerably improved relative to the Clayton–Engquist boundary condition and nearly the same as that in the PML.

LED光柱在仪表行业的应用

LED作为一种新型光源,在国内开创了巨大的市场,应用面几乎遍及每个行业。仪表行业也进入了用LED制作的模拟条图替代仪表指针的新阶段。由于LED自身发光,色彩丰富,并具有抗过载、抗振动、平均无故障工作时间在5万小时左右等优点,是仪表显示方式一个新的飞跃。本文就LED模拟条图(又称LED光柱显示器)替代仪表指针的有关情况和问题,结合实践进行讨论和阐述。

Stress verification of a TLP under extreme wave environment

Stress response of a tension leg platform （TLP） in extreme environments was investigated in this paper. A location on one of the gussets was selected as the object point, where directional stresses were numerically simulated and also experimentally verified by a strain gage. Environmental loading and the platform＇s structural strength were analyzed in accordance with industrial standards, utilizing linear wave theory and the finite element method （FEM）. The fast Fourier transform technique was used to calculate the stress response amplitude operators （RAO） from the records of measurements. A comparison was performed between the stress RAO of the numerical simulation and that of the actual measurements. The results indicated that the stress RAO of the numerical simulation fitted well with measured data at specified wave headings with different periods.

Analysis of granular assembly deformation using discrete element method

The discrete element method is used to simulate specimens under three different loading conditions（conventional triaxial compression,plane strain,and direct shear）with different initial conditions to explore the underlying mechanics of the specimen deformation from a microscale perspective.Deformations of specimens with different initial void ratios at different confining stresses under different loading conditions are studied.Results show that the discrete element models successfully capture the specimen deformation and the strain localization.Particle behaviors including particle rotation and displacement and the mesoscale void ratio distributions are used to explain the strain localization and specimen deformation.It is found that the loading condition is one of the most important factors controlling the specimen deformation mode.Microscale behavior of the granular soil is the driving mechanics of the macroscale deformation of the granular assembly.

2D multi-scale hybrid optimization method for geophysical inversion and its application

Local and global optimization methods are widely used in geophysical inversion but each has its own advantages and disadvantages. The combination of the two methods will make it possible to overcome their weaknesses. Based on the simulated annealing genetic algorithm （SAGA） and the simplex algorithm, an efficient and robust 2-D nonlinear method for seismic travel-time inversion is presented in this paper. First we do a global search over a large range by SAGA and then do a rapid local search using the simplex method. A multi-scale tomography method is adopted in order to reduce non-uniqueness. The velocity field is divided into different spatial scales and velocities at the grid nodes are taken as unknown parameters. The model is parameterized by a bi-cubic spline function. The finite-difference method is used to solve the forward problem while the hybrid method combining multi-scale SAGA and simplex algorithms is applied to the inverse problem. The algorithm has been applied to a numerical test and a travel-time perturbation test using an anomalous low-velocity body. For a practical example, it is used in the study of upper crustal velocity structure of the A＇nyemaqen suture zone at the north-east edge of the Qinghai-Tibet Plateau. The model test and practical application both prove that the method is effective and robust.

CFD modeling of methane distribution at a continuous miner face with various curtain setback distances

Knowledge of the airflow patterns and methane distributions at a continuous miner face under different ventilation conditions can minimize the risks of explosion and injury to miners by accurately forecasting potentially hazardous face methane levels. This study focused on validating a series of computational fluid dynamics(CFD) models using full-scale ventilation gallery data that assessed how curtain setback distance impacted airflow patterns and methane distributions at an empty mining face(no continuous miner present). Three CFD models of face ventilation with 4.6, 7.6 and 10.7 m(15, 25, and 35 ft) blowing curtain setback distances were constructed and validated with experimental data collected in a full-scale ventilation test facility. Good agreement was obtained between the CFD simulation results and this data.Detailed airflow and methane distribution information are provided. Elevated methane zones at the working faces were identified with the three curtain setback distances. Visualization of the setback distance impact on the face methane distribution was performed by utilizing the post-processing capability of the CFD software.

Forming condition of transient saturated zone and its distribution in residual slope under rainfall conditions

Rainfall, as one of the most significant factors triggering the residual soil slope failure, leads to not only the reduction of soil shear strength, but also the increase of soil weight and the decrease of matric suction as well. All these modifications in soil properties have important influence on the slope stability. The water infiltration and redistribution inside the slope are the preconditions of the slope stability under rainfall conditions. Based on the numerical simulation via finite element method, the water infiltration process under rainfall conditions was studied in the present work. The emphases are the formation, distribution and dissipation of transient saturated zone. As for the calculation parameters, the SWCC and the saturated permeability have been determined by pressure plate test and variable head test respectively. The entire process(formation, development, dissipation) of the transient saturated zone was studied in detail. The variations of volumetric water content, matric suction and hydraulic gradient inside the slope, and the eventually raise of groundwater table were characterized and discussed, too. The results show that the major cause of the formation of transient saturated zone is ascribed to the fact that the exudation velocity of rainwater on the wetting front is less than the infiltration velocity of rainfall; as a result, the water content of the soil increases. On the other hand, the formation and extension of transient saturated zone have a close relationship with rainfall intensity and duration. The results can help the geotechnical engineers for the deeper understanding of the failure of residual slope under rainfall condition. It is also suggested that the proper drainage system in the slope may be the cost-effective slope failure mitigation method.

Numerical Modeling of Floating Oil Boom Motions in Wave-Current Coupling Conditions

Containment booms are commonly used in collecting and containing spilled oil on the sea surface and in protecting specific sea areas against oil slick spreading.In the present study,a numerical model is proposed based on the N-S equations in a mesh frame.The proposed model tracks the outline of the floating boom in motion by using the fractional area/volume obstacle representation technique.The boom motion is then simulated by the technique of general moving object.The simulated results of the rigid oil boom motions are validated against the experimental results.Then,the failure mechanism of the boom is investigated through numerical experiments.Based on the numerical results,the effects of boom parameters and dynamic factors on the oil containment performance are also assessed.

Comparison of the Radial Compliance of Three Kinds of Vascular Prostheses and Pig′s Carotid Based on Dynamic-simulated Condition

There are some problems in the vascular prostheses, which influence the health of the patients. This paper aims to the radial compliance of three kinds of vascular prostheses and the pig＇s carotid based on the dynamic-simulated condition. The radial compliance of knitted structure vascular prostheses with crimps ranged from 2.52% to 0.94%/100 mmHg, which was superior to e-FFFE and woven prostheses＇, ranged from 0.73% to 0.31%/100 mmHg and from 0.81% to 0.22%/100 mmHg. But comparing with the radial compliance of pig＇s carotid, ranged from 7.21% to 10.04% /100 mmHg, there was a big gap between them. And also the trend of the radial compliance of vascular prostheses was different from the real pig＇s carotid. There is a lot of work left to improve the radial compliance, not only to change the vascular prostheses＇ compliance, but also to meet with the real vascular.

Dynamic Response Analysis of Towed Cable During Deployment/Retrieval

A numerical approach was developed to analyze the transient behavior of towed cable during ac- tively controlled deployment/retrieval (DR).The cable motion is described by the lumped parameter method, its corresponding boundary conditions are presented.In view of its varying length during DR,two auxiliary arguments are introduced to describe its continuous varying length and discrete number of nodes(equations), the length is determined by the pay out(or reel-in) rate,which is then used to determine the node number by a logic relation.For the discrete mathematical model of towed cable,an algorithm was developed to deal with the discrete governing equations.The simulation results indicate that the cable experiences more com- plex motions due to its varying length,and tension fluctuates seriously in the startup and ending stage of deployment/retrieval.The effect of towing ship's motion in waves on cable during deployment/retrieval is also considered via numerical simulation.

Solution of Terzaghi one-dimensional consolidation equation with general boundary conditions

Boundary conditions for the classical solution of the Terzaghi one-dimensional consolidation equation conflict with the equation＇s initial condition. As such, the classical initial-boundary value problem for the Terzaghi one-dimensional consolidation equation is not well-posed. Moreover, the classical boundary conditions of the equation can only be applied to problems with either perfectly pervious or perfectly impervious boundaries. General boundary conditions are proposed to overcome these shortcomings and thus transfer the solution of the Terzaghi one-dimensional consolidation equation to a well-posed initial boundary value problem. The solution for proposed general boundary conditions is validated by comparing it to the classical solution. The actual field drainage conditions can be simulated by adjusting the values of parameters b and c given in the proposed general botmdary conditions. For relatively high coefficient of consolidation, just one term in series expansions is enough to obtain results with acceptable accuracy.

Influence of depth-thickness ratio of mining on the stability of a bedding slope with its sliding surface in concave deformation

In order to study the influence of depth-thickness ratio on bedding slope stability, whose sliding surface is flexural concave in shape under mining conditions, this paper aims to study the characteristics ofdeformarion and damage of bedding sliding with depth-thickness ratios of 200：1,150：1,120：1,100：1 and 50：1 by adopting numerical simulation analysis software combined with laboratory-made ＂under the influence of mining variable sliding surface slope similar simulation test bed＂, and to propose identification methods for slope stability under the infuence of mining. The results show that mining activities under the slope reduce slope stability. With a decrease in the mining depth ratio, the influence of mining on the slope increases gradually, and the damage to the slope gradually expands, the stability of the slope grad- ually reduces, fracture occurs on the slope toe and the central fissure gradually develops to the surface, and reaches slide threshold when the depth-thickness ratio is 50：1.

Prediction of Fluid Velocity Distribution near a Rising Bubble

Flow and concentration fields of liquid phase in a gas-liquid contacting system are simulated to showthe Rayleigh convection by utilizing the finite-element method. The Schlieren images in CO2-ethanol system provided direct visual verification of the present simulation, and the simulated results were well consistent with theexperimental observation. The influence of the Rayleigh convection on mass transfer is analyzed qualitatively andquantitatively based on the simulated and the experimental results.

3D Simulation of Two-bar Warp-knitted Structures

In this study, 3D computer modeling of simple warp-knitted structures is achieved based on 3D model of warp-knitted loops. Firstly, according to the studying on the geometric structure of warp-knitted loops, Goktepe＇s 3D solid yarn model is developed, and the dimensions of the warp-knitted loops are obtained; then 3D models of stitch defined by eleven given points and in-lay defined by five given points are built with the method of Non-Uniform Rational B-Spline （NURBS） curves and surfaces. Secondly, according to the chain notations of warp-knitted structures, the loop＇s shape can be decided, and with the 3D models the loops can be connected freely and smoothly in some special warp-knitted structures, such as miss-lapping and two- course in-lay. At last, with the tools of Visual C ＋＋ and OpenGL, computer 3D simulation of two-bar warp-knitted fabrics is successfully realized, taking the factor of fabric light and materials into 3D structural model.

A New Car Following Model:Comprehensive Optimal Velocity Model

In this paper, we present a new ear-following model, i.e. comprehensive optimal velocity model （COVM）, whose optimal velocity function not only depends on the following distance of the preceding vehicle, but also depends on the velocity difference with preceding vehicle. Simulation results show that COVM is an improvement over the previous ones theoretically. Then, the stability condition of the model is obtained by the linear stability analysis, which has shown that the model could obtain a bigger stable region than previous models in the phase diagram. Through the nonlinear analysis, the Burgers, Korteweg-de Vries （KdV） and modified KdV （mKdV） equations are derived for the triangular shock wave, the soliton wave, and the kink-antikink soliton wave. At the same time, numerical simulations are also carried out to show that the model could simulate these density waves.

Evaluation of space radius formed by blasting pressure with linear charges

Based on the mechanism analysis of space form caused by blasting with lin- ear charges, elastic-plastic model of space form caused by blasting was established in this paper. In terms of state equation of blasting and the balance of quality, evaluation formula based on elastic-plastic to estimate space diameter caused by blasting with lin- ear charges was given. The procedure structure of evaluation was introduced. We did 18 experiments on situ and compared experiments results with evaluation ones. They are correspondent very well. Then a new method of evaluating underground space di- ameters caused by blasting with linear charges was given. The method has more great guidance significance to the optimism plan of the new blasting technology that utilizes the explosion effect of the explosive to compact the soil to form the underground space.

Numerical Simulation of the Flow around Two-dimensional Partially Cavitating Hydrofoils

In the present study, a new approach is applied to the cavity prediction for two-dimensional （2D） hydrofoils by the potential based boundary element method （BEM）. The boundary element method is treated with the source and doublet distributions on the panel surface and cavity surface by usethe of the Dirichlet type boundary conditions. An iterative solution approach is used to determine the cavity shape on partially cavitating hydrofoils. In the case of a specified cavitation number and cavity length, the iterative solution method proceeds by addition or subtraction of a displacement thickness on the cavity surface of the hydrofoil. The appropriate cavity shape is obtained by the dynamic boundary condition of the cavity surface and the kinematic boundary condition of the whole foil surface including the cavity. For a given cavitation number the cavity length of the 2D hydrofoil is determined according to the minimum error criterion among different cavity lengths, which satisfies the dynamic boundary condition on the cavity surface. The NACA 16006, NACA 16012 and NACA 16015 hydrofoil sections are investigated for two angles of attack. The results are compared with other potential based boundary element codes, the PCPAN and a commercial CFD code （FLUENT）. Consequently, it has been shown that the results obtained from the two dimensional approach are consistent with those obtained from the others.