Droplet Self-Driven Characteristics on Wedge-Shaped Surface with Composite Gradients:A Molecular Dynamics Study

The self-driven behavior of droplets on a functionalized surface,coupled with wetting gradient and wedge patterns,is systematically investigated using molecular dynamics(MD)simulations.The effects of key factors,including wedge angle,wettability,and wetting gradient,on the droplet self-driving effect is revealed from the nanoscale.Results indicate that the maximum velocity of droplets on hydrophobic wedge-shaped surfaces increases with the wedge angle,accompanied by a rapid attenuation of driving force;however,the average velocity decreases with the increased wedge angle.Conversely,droplet movement on hydrophilic wedge-shaped surfaces follows the opposite trend,particularly in terms of average velocity compared to the hydrophobic case.Both wedge-shaped and composite gradient wedge-shaped surfaces are found to induce droplet motion,with droplets exhibiting higher speeds and distances on hydrophobic surfaces compared to hydrophilic surfaces,regardless of surface type.Importantly,the inclusion of wettability gradients significantly influences droplet motion,with hydrophobic composite gradient wedge-shaped surfaces showing considerable improvements in droplet speed and distance compared to their hydrophilic counterparts.By combining suitable wettability gradients with wedge-shaped surfaces,the limitations inherent in the wettability gradient range and wedge-shaped configuration can be mitigated,thereby enhancing droplet speed and distance.The findings presented in this paper offer valuable insights for the design of advanced functional surfaces tailored for manipulating droplets in real-world applications.

Distribution and engulfment behavior of TiB_2 particles or clusters in wedge-shaped copper casting ingot

Wedge-shaped copper casting experiment was conducted to study the engulfment behavior of TiB2 particle and the interaction between particle or cluster and the solid/liquid front in commercial pure aluminum matrix. The experimental results show that the particle size distribution obeys two separate systems in the whole wedge-cast sample. Furthermore, it is found that the big clusters are pushed to the center of the wedge shaped sample and the single particle or small clusters consisting of few particles are engulfed into the α-Al in the area of the sample edge. The cluster degree of particles varies in different areas, and its value is 0.2 and 0.6 for the cluster fraction in the edge and in the center of the wedge sample, respectively. The cluster diameter does not obey the normal distribution but approximately obeys lognormal distribution in the present work. More importantly, in the whole sample, the particle size obeys two separate log-normal distributions.

The interaction between a screw dislocation and a wedge-shaped crack in one-dimensional hexagonal piezoelectric quasicrystals

Based on the fundamental equations of piezoelasticity of quasicrystal material,we investigated the interaction between a screw dislocation and a wedge-shaped crack in the piezoelectricity of one-dimensional hexagonal quasicrystals.Explicit analytical solutions are obtained for stress and electric displacement intensity factors of the crack,as well as the force on dislocation.The derivation is based on the conformal mapping method and the perturbation technique.The influences of the wedge angle and dislocation location on the image force are also discussed.The results obtained in this paper can be fully reduced to some special cases already available or deriving new ones.

Numerical prediction of thermo-hydrodynamics on the gas-lubricated film in wedge-shaped microchannel

One wedge-shaped microchannel was established,and the hydrodynamic properties of the wedge-shaped gas film were comprehensively investigated.The Navier-Stokes equations coupled with the full energy equation were adopted to mainly analyze the lubrication hydrodynamics of the gas film,as the horizontal plate was viewed as the adiabatic wall or the horizontal plate temperature was equal to the tilt plate temperature.A higher gas film temperature strengthened the rarefaction effect,and the more rarefied gas weakened the squeeze.Meanwhile,the vertical flow across the gas film could indicate the relation between the velocity vector and the gas film squeeze and expansion.The adiabatic horizontal plate could resist the heat conduction and enhance the rarefaction effect,and thus the direction of motion of the gas molecules was easier to be changed.

Asymmetric and Single-Side Splitting of Dissipative Solitons in Complex Ginzburg–Landau Equations with an Asymmetric Wedge-Shaped Potential

We report some novel dynamical phenomena of dissipative solitons supported by introducing an asymmetric wedge-shaped potential(just as a sharp ‘razor') into the complex Ginzburg–Landau equation with the cubicquintic nonlinearity. The potentials corresponding to a local refractive index modulation with breaking symmetry can be realized in an active optical medium with respective expanding antiwaveguiding structures. Using the razor potential acting on a central dissipative soliton, possible outcomes of asymmetric and single-side splitting of dissipative solitons are achieved with setting different strengths and steepness of the potentials. The results can potentially be used to design a multi-route splitter for light beams.

Design of a Wedge-Shaped Toroidal Field Winding for KTX Device

The KTX device is a reversed field pinch （RFP） device currently under construction. Its maximum plasma current is designed as 1 MA with a discharge time longer than 100 ms. Its major radius is 1.4 m and its minor radius is 0.55 m. One of the most important problems in the magnet system design is how to reduce the TF magnetic field ripple and error field. A new wedge- shaped TF coil is put forward for the KTX device and its electromagnetic properties are compared with those of rectangular-shaped TF coils. The error field B,I/Bt of wedge-shaped TF coils with 6.4 degrees is about 6% as compared with 8% in the case of a rectangular-shaped TF coil. Besides, the wedge-shaped TF coils have a lower magnetic field ripple at the edge of the plasma region, which is smaller than 7.5% at R=1.83 m and 2% at R=l.07 m. This means that the tokamak operation mode may be feasible for this device when the plasma area becomes smaller, because the maximum ripple in the plasma area of the tokamak model is always required to be smaller than 0.4%. Detailed analysis of the results shows that the structure of the wedged-shape TF coil is reliable. It can serve as a reference for TF coil design of small aspect ratio RFPs or similar torus devices.

全自动移栽机送苗装置的优化设计与试验

【目的】解决目前全自动移栽机硬质苗盘钵苗输送技术不成熟,送苗准确率和送苗效率过低的问题。【方法】在龙门架全自动移栽机取投苗装置的基础上,针对钵苗输送设计一种全自动送苗装置;纵向输送机构为该装置的关键部件,采用偏置曲柄滑块结构,输送机构的气缸行程和棘轮齿数为设计变量,通过理论分析确定纵向输送机构的自由度、理论角位移及理论气缸行程;采用SolidWorks软件建立关键部件三维模型,采用Adams软件对关键部件进行动力学仿真分析并优化;对优化后的送苗装置样机进行试验验证。【结果】优化后的纵向输送机构气缸行程为73.80 mm,角位移为48°,棘轮齿数为60;优化后的仿真结果表明,单次输送,气缸推动棘爪走过8个齿,棘轮转动角度为48°,连续输送时,误差控制在允许范围内。对送苗装置进行输送试验,得到机器的平均送苗精度达98.90%,单次送苗最大误差为-0.91 mm,单盘累计误差最大为-2.48 mm。【结论】优化后的送苗装置能够完成硬质苗盘钵苗自动输送任务,误差控制在允许范围内,能够实现精准送苗,满足农业生产需求。

Configuration Optimization of Two-Rail Sliders on Dynamic Characteristic

An optimal design methodology for the configuration of two rail slider was proposed to get better dynamic performance. The taper length, taper height and the rail width of the reading/writing head are considered as design variables. The complex geometry method is utilized as the search scheme in the optimization process. Optimization results show that the new slider has better dynamic characteristics and is more stable than the original designed slider. The optimization process also demonstrates that the optimum model and optimum method is effective.

Influence of wall slip on the hydrodynamic behavior of a two-dimensional slider bearing

In the present paper, a multi-linearity method is used to address the nonlinear slip control equation for the hydrodynamic analysis of a two-dimensional （2-D） slip gap flow. Numerical analysis of a finite length slider bearing with wall slip shows that the surface limiting shear stress exerts complicated influences on the hydrodynamic behavior of the gap flow. If the slip occurs at either the stationary surface or the moving surface （especially at the stationary surface）, there is a transition point in the initial limiting shear stress for the proportional coefficient to affect the hydrodynamic load support in two opposite ways： it increases the hydrodynamic load support at higher initial limiting shear stresses, but decreases the hydrodynamic load support at lower initial limiting shear stresses. If the slip occurs at the moving surface only, no fluid pressure is generated in the case of null initial limiting shear stress. If the slip occurs at both the surfaces with the same slip property, the hydrodynamic load support goes off after a critical sliding speed is reached. A small initial limiting shear stress and a small proportionality coefficient always give rise to a low friction drag.

Comparison and analysis of two Coulomb friction models on the dynamic behavior of slider-crank mechanism with a revolute clearance joint

The objective of this study is to investigate the effects of the Coulomb dry friction model versus the modified Coulomb friction model on the dynamic behavior of the slider-crank mechanism with a revolute clearance joint. The normal and tangential forces acting on the contact points between the journal and the bearing are described by using a Hertzian-based contact force model and the Coulomb friction models, respectively.The dynamic equations of the mechanism are derived based on the Lagrange equations of the first kind and the Baumgarte stabilization method. The frictional force is solved via the linear complementarity problem(LCP) algorithm and the trial-and-error algorithm.Finally, three numerical examples are given to show the influence of the two Coulomb friction models on the dynamic behavior of the mechanism. Numerical results show that due to the stick friction, the slider-crank mechanism may exhibit stick-slip motion and can balance at some special positions, while the mechanism with ideal joints cannot.

INVESTIGATIONS OF THE INFLUENCE OF TAPER CONTAMINATION ON THE FLYING CHARACTERISTICS OF A SLIDER

The influence of taper contamination on the static and dynamic characteristics of a slider is studiedin detail. Two models of taper contamination, including the effect of skew angle and the number of the railwith taper contamination as well as the amount of contaminator on the taper,are investigated respectively. Anequivalent scheme is applied to evaluate the frequency responses with different flying attitudes in three de-grees of freedom. Ca1culations show that whether model is considered and how many tapers are contaminated,the static and dynamic characteristics of the slider change little in a very large contamination scale,but oncethe amount of contaminator exceeds some limit,the flying attitude of the slider is degraded catastrophically,which is easy to cause the slider crash. The skew angle,when it is large enough,may ameliorate or deterioratethe flying characteristics of the slider depending on the slider attitude when the transverse air flow passesthrough it.

Analysis and Optimization of Passenger Side Knee Slider Compression in Front Impact

The influences of different design factors,as well as dummy posture,on an occupants' knee slider compression,were studied in this paper.Based on the vehicle geometry data,the simulation model,including both the multi-rigid-body and finite element(FE)part,was built up and validated with China New Car Assessment Program(C-NCAP)full impact to ensure the accuracy of the model.By adjusting the design parameters and the posture of the femur and lower leg,different factors affecting the passengers' knee slider compression were evaluated,with the help of MAthematical DYnamic MOdel(MADYMO)simulations.The study indicated that the leg posture,the stiffness of the IP and angles of the carpet have significant effects on the knee slider compression in this case.By decreasing the angle between the femur and lower leg from 133° to 124°,the maximum knee slider compression was decreased by 17.3% and by scaling the IP stiffness from 1 to 0.7,it could be decreased by 18.6%.Also,decreasing the angles of the carpet from 28° to 37°can help reduce the knee slider compression by 18.3%.

A method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed presses

A new method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed mechanical presses was put forward. By analyzing the kinematic characteristics of a center-located slider-crank mechanism whose crank rotates at a constant angular velocity,the kinematic parameters of the slide,connecting rod and crank were formulated approximately. On the basis of the results above,three inertia forces and the input moment in the mechanism during its idle running were investigated and formulated by dynamic analysis. A verification experiment was performed on a slider-crank mechanism at a high-speed press machine. The forces derived from the established formulas were compared respectively with those obtained by the ADAMS software and the classical method of connecting rod mass substitution. It was experimentally found that the proposed formulas have an improved performance over related earlier techniques. By use of these results,a 1 000 kN 1 250 rpm four-point high-speed press machine was designed and manufactured. The slide of this press is driven by four sets of slider-crank mechanisms with symmetrical layout and opposite rotation directions to counterbalance the horizontal inertia forces. Four eccentric counterbalance blocks were designed to counterbalance the vertical force after their mass and equivalent eccentric radius were formulated. The high-speed press machine designed by the proposed counterbalance method has worked with satisfactory performance and good dynamic balance for more than four years in practical production.

Unified gas-kinetic simulation of slider air bearing

The unified gas-kinetic scheme （UGKS） is presented and used in this letter to study the slider air bearing problem. The UGKS solutions are first val- idated by comparison with direct simulation Monte Carlo results. After valida- tion, the UGKS is used to study the air-bearing problem under different non- equilibrium conditions. On the surface of the slider, the dependency of the gas pressure and normal force on the Mach and Knudsen numbers are fully evaluated. The non-equilibrium effect on the force loading in the whole transition regime up to the free molecular limit is also studied.

Integral Transform Method for a Porous Slider with Magnetic Field and Velocity Slip

Current research is about the injection of a viscous fluid in the presence of a transverse uniform magnetic field to reduce the sliding drag.There is a slip-on both the slider and the ground in the two cases,for example,a long porous slider and a circular porous slider.By utilizing similarity transformation Navier-Stokes equations are converted into coupled equations which are tackled by Integral Transform Method.Solutions are obtained for different values of Reynolds numbers,velocity slip,and magnetic field.We found that surface slip and Reynolds number has a substantial influence on the lift and drag of long and circular sliders,whereas the magnetic effect is also noticeable.

Design and Modeling of Femto Air Bearing Slider

This paper presents the studies of the performance of an improved femto air bearing slider which is optimized based on the past studies and effort. The flying characteristics performance of this novel femto slider is relatively stable over different radii. This optimized slider achieved a flying height of 3 nm, with variation of about 0.2 nm. The variations for pitch and roll values are 6 μrad and 0.9 μrad respectively. In the studies for the effect of side rail on flying characteristics, it was found that there exists transition of pitch value when the side rail is located very close to the leading edge. The modulation of flying height reduces greatly when the areas of double shallow steps increase. The roll variation reduces when the flat double shallow steps profile is modified into a “V-Shape” profile.

Dynamic Simulation of a Smart Crank and Slider Mechanism

In this paper, a smart crank and slider mechanism is analyzed mostly from a dynamic view. By means of dynamic explicit finite element method, 3D nonlinear structure is simulated. It is proved that the mechanism can effectively accomplish smart movement prescribed. And in order to ensure reciprocal movement with higher frequency, measures should be taken to avoid over heating of parts. Compared with internal energy, kinetic energy of total rigid body is dominating, and Ydirection equivalent rigid velocity is much higher than X direction velocity. Equivalent rigid velocity of all parts is consistent with respective movement condition. For both energy and velocity, slider effect is dominating. Three direction equivalent inertia force oscillates. Force amplitude in Y-direction is comparitively the greatest.

美国教授Slider来华讲学

应石油天然气总公司开发部的邀请.美国俄亥荷州立大学化学工程系油藏工程学教授Slider 于一九九零年十月二十六日来华讲学。十月二十九日至十一日,Slder 先生在华北油田油气井测试公司讲授油藏工程学。讲授的主要内容是油藏工程学的基本知识,即达西方程,油藏流体的稳定态流动,不稳定态流动和假稳定态流动,以及适用于这些流动状况的方程及这些方程的应用。

在VC++工具栏中添加Slider控件实现视图实时缩放

用Slider控件的滑动来实时控制视图平滑地缩放,利用控件的范围控制缩放大小.程序通过VC++的消息反射机制,添加必要的消息映射函数,实现用Slider控件控制图形显示区的目的.结合VC++平台,用Sli-der控件能方便地实现控制视图缩放,也比单纯放大缩小视图要直观连续,更适合用户的需要.同时,利用同样的思想,也可以很方便地实现其他界面上的改进.

Dynamic analysis of rotating flexible disk subjected to double slider loading systems

Rotating disk subjected to stationary slider loading system is a very common mechanical structure. This paper investigates the multibody dynamics of a rotating flexible annular thin disk subjected to double slider loading systems. Along the rotating disk radial and circumferential directions, two stationary slider loading systems are distributed. System dynamic model is solved by Galerkin＇s method, and then natural frequency, dynamic stability and mode shape are determined with a quadratic eigenvalue problem. Effects of the distributing positions and interaction mechanism of the double slider loading systems on natural frequency, dynamic stability and mode shape are discussed and investigated.