Open optimization in two-dimensional lathe control systems

Optimization of turning in a numerically controlled lathe with open control of the cutting speed and closed control of the supply improves the operational efficiency in constantly changing conditions. An algorithm is proposed for determining the most economical cutting speed.     

On the motion of the structure varying multibody systems with two-dimensional dry friction

In the present paper the dynamics of the structure varying multibody systems caused by stick-slip motion with two-dimensional dry friction are analyzed. The methods to determine friction force both in stick and slip states are described. The direct method of considering the wagon bogie system as a structure varying system was used to consider two dimensional friction at the wheelset-side frame connection. The concept of friction direction angle used to determine the friction force components of two-dimensional dry friction both in the stick and slip motion states was used. A speed depended friction coefficient was used and described approximately by hyperbolic secant function. All switch conditions were derived and friction forces both for stick and slip states. Some simulation results are provided.     

Some dynamic properties of systems with cam mechanisms

After finding the time response of linear systems to a series of typical acceleration pulses analytically, the corresponding responses of non-linear systems (springs, backlash) are studied. Investigations are performed on digital and on analog computers. It is found that dwell periods in the follower motion are always accompanied by free vibrations with random beats if backlash is present in a kinematic pair, and that beats will not occur if the spring properties of the linkage are non-linear. Recommendations for the proper choice of the parameters of the mechanism and acceleration of the follower motion are given.     

二维光子晶体光波导透射特性的研究

用时域有限差分方法(FDTD)研究光波在光子晶体光波导中的传播规律,发现不同形状的波导能够导引不同频率的光波。光子晶体波导的带隙宽度和透射系数与该波导的结构和参数都有很大的关系,随着介质柱半径的变化,带隙呈现一定的变化规律,介质柱半径变小,该波导的带隙向高频方向移动,且带隙的宽度变宽;而介质柱半径变大时,光波的透射峰的峰值却变得比较大,损耗变小。研究结果为光子器件的设计提供了理论依据。     

Low-distortion resistive anodes for two-dimensional position-sensitive MCP systems

Microchannel plates (MCPs) are frequently employed with resistive anodes to detect charged particles or photons and yield analog signals from which event positions can be decoded. We discuss an anode geometry devised by C.W. Gear that offers theoretically distortionless encoding of Cartesian event positions into pulse charge ratios. Electron beam images taken with such an anode are shown, and confirm the usefulness of the approach.     

Simulation of technological systems in custom production

Russian Engineering Research -     

异构系统动态双向融合仿真技术研究

异构的计算机辅助工程软件ANSYS与ADAMS通过模型转化或联合仿真等方法,能协同求解刚弹(柔)耦合等特定问题,但难以准确求解电、热、磁场中的多体动力学仿真问题.根据牛顿插值法基本思想,提出了异构仿真环境动态双向融合法,将连续的仿真过程离散为n个步长足够小的子过程,通过构建数据交互平台,分别独立传递存储模型信息与仿真数据,动态更新边界条件,使得两个异构系统双向融合,实现完整问题的分步求解.该方法克服了传统方法误差大、直观性差等缺点,解决了ADAMS与ANSYS不能双向融合仿真的问题.实例表明,该方法应用效果好,为求解异构环境仿真的融合提供了一种有效途径.     

Novel frictional algorithm implementing angular increment for two-dimensional frictional systems

This study proposes a new frictional algorithm that implements angular increment. The proposed algorithm is used to solve the numerical solutions of dynamic problems in two-dimensional frictional systems. It can accurately obtain the motion responses of a lumped mass under time-varying external forces, and it can compensate for the shortcomings of the numerical frictional algorithm that implements a time step. Specifically, the proposed algorithm 1) overcomes the difficulties encountered when the angles between resultant tangential forces and slip motion are infinitely close, 2) provides accurate solutions for two-dimensional systems under fierce planar motions, and 3) calculates the responses of the mass within a reasonable period. We compare the computation accuracy, efficiency, and robustness of the proposed frictional algorithm and the previous frictional algorithm [1] through several representative scenarios. We reveal that the proposed algorithm has superior computation accuracy, efficiency, and robustness for two-dimensional frictional problems involving slip/stick transitions and sharp bending.

     

Radiofrequency sensing systems based on emerging two-dimensional materials and devices

As one of the most promising platforms for wireless communication, radiofrequency(RF)electronics have been widely advocated for the development of sensing systems. In particular,monolayer and few-layer two-dimensional(2D) materials exhibiting extraordinary electrical properties not only can be integrated to improve the performance of RF circuits, but also to display exceptional sensing capabilities. This review provides an in-depth perspective of current trends and challenges in the application ...     

System identification of two-dimensional continuous-time systems using wavelets as modulating functions

In this paper, parameter identification of two-dimensional continuous-time systems via two-dimensional modulating functions is proposed. In the proposed method, trigonometric functions and sine-cosine wavelets are used as modulating functions. By this, a partial differential equation on the finite-time intervals is converted into an algebraic equation linear in parameters. The parameters of the system can then be estimated using the least square algorithms. The underlying computations utilize a two-dimensional fast Fourier transform algorithm, without the need for estimating the unknown initial or boundary conditions, at the beginning of each finite-time interval. Numerical simulations are presented to show the effectiveness of the proposed algorithm.     

Simulation of the surface-layer properties in ultrasonic planing

In the ultrasonic-planing method proposed, torsional oscillations of the tool are used to machine external cylindrical surfaces. Formulas describing the indenter trajectory over the surface of the part are presented. The indenter trajectory and the machining parameters are such that the required microrelief and microprojection configuration may be obtained, depending on the specified surface properties.     

Stroboscopic two-dimensional ultrasonic velocity profiling for measuring flow transition in Taylor Couette systems

Flow characterization in a Taylor Couette system was made by investigating the radial velocity component with Ultrasonic Doppler Velocimetry based flow mapping. With the technique presented in this work, it is possible to measure the radial velocity components for variable axial position in a Couette cell within Taylor vortex flow (TVF), wavy vortex flow (WVF), modulated vortex flow (MVF) as well as spiral vortex domains in a conical shaped gap. The resulting maps for the different flow states show the location of vortices in the annular gap between the inner and outer cylinder. Cylindrical and conical concentrically rotating inner bodies were applied and respective flow patterns were analyzed. The method uses a stroboscopic triggering to synchronize flow measurements and rotational motion. The oscillation frequency f of unsteady motion in WVF, MVF, and spirals can be obtained from the power spectrum of velocity. The UVP transducer was preferably positioned in radial direction, perpendicular to the surface of the inner rotating body for measuring the radial velocity component. At the same time, the transducer was moved with constant velocity vertically along the outer cylinder height.     

Synergetic properties of mechatronic manipulation systems

The synergetic properties of mechatronic manipulation systems are discussed.     

大型抓斗卸船机起升系统钢丝绳工作特性研究

卸船机传动系统在变速变载的复杂工况下,将产生较大的动载荷并传递给钢丝绳,产生振动与疲劳.通过分析2 250 t.h-1大型抓斗卸船机传动系统的工作原理,建立起升、开闭钢丝绳的载荷谱和受力模型,并建立了钢丝绳的有限元模型,分析了钢丝绳在最大载荷作用下的静力学特性和开闭工况下动态响应,得到了钢丝绳在工作状态的应力与变形规律,为卸船机的使用、保养和维护提供了参考.     

基于合作的面向人的生产系统的仿真研究

企业为了迎合顾客的多样化需求，一种按规格定制的方法，即快速实现多品种、小批量的生产方式。在从大批量生产方式转向多品种小批量生产方式的过程中，基于合作的面向人的生产过程越来越受青睐，其显著的特点就是U型的生产线或制造单元，能充分利用人的主观能力。为了实现按规格定制的生产方式，就需要建立面向人的生产过程。基于此，需要一种量化的方法来分析和评价生产过程中的人员“合作”及其它因素。文章将对在面向人的生产过程中的人员自主的合作过程进行建模，将合作模型应用于生产仿真并进行评价。     

Scanning tunneling microscope with two-dimensional translator

Since the invention of the scanning tunneling microscope (STM), it has been a powerful tool for probing the electronic properties of materials. Typically STM designs capable of obtaining resolution on the atomic scale are limited to a small area which can be probed. We have built an STM capable of coarse motion in two dimensions, the z- and x-directions which are, respectively, parallel and perpendicular to the tip. This allows us to image samples with very high resolution at sites separated by macroscopic distances. This device is a single unit with a compact design making it very stable. It can operate in either a horizontal or vertical configuration and at cryogenic temperatures.     

动力总成悬置系统动态特性仿真分析

动力总成悬置系统是汽车振动系统的一个重要子系统,对改善汽车平顺性和舒适性有很大的影响。应用拉格朗日法建立了六自由度动力总成悬置系统的数学模型,并用Newmark法和Simulink仿真模型两种方法对动力总成悬置系统怠速工况进行了仿真分析,两种方法的仿真结果相近,说明模型的正确性,在此基础上对动力总成悬置系统在怠速工况下进行了动特性分析,最后将仿真动特性结果和实测进行了对比,仿真结果和实验结果基本一致,说明其具有工程应用价值。     

Stochastic simulation of electron-hole recombination in two-dimensional and three-dimensional inhomogeneous semiconductors. Part II. Simulation results

This paper describes the stochastic models of electron-hole recombination in inhomogeneous semiconductors in two-dimensional and three-dimensional cases, which were developed on the basis of discrete (cellular automaton) and continuous (Monte Carlo method) approaches. The particle recombination kinetics in pure diffusion and diffusion with tunneling is studied. There is a certain difference revealed between the behavior of electron-hole spatial correlations calculated by discrete and continuous models and the nature of segregation formation in three-dimensional semiconductors associated with that behavior. The comparative analysis of the simulation characteristics determined via cellular automaton and continuous recombination models is carried out.     

微米行程微膨胀型热开关热特性的仿真与试验

为了提高空间热控分系统的散热调节能力和热环境适应性,设计了一种微米行程的微膨胀型热开关。介绍了热开关的结构组成和工作原理,通过理论-仿真-试验相结合的方式,计算评估了热开关的断开热阻、闭合热阻和开关比等关键热特性。依据热阻网络串并联关系计算热开关的理论特性,断开热阻为301.71K/W,闭合热阻为1.06K/W,开关比约为283.6。基于有限元模型分析热开关断开/闭合过程的瞬态热特性,热端发热功率为18 W时,热开关闭合响应时间为340s,触发温度为35.5℃,闭合热阻约为2.3K/W。在2次热开关性能测试试验中,闭合热阻和开关比分别为1.08K/W、279.4和1.67K/W、180.7,试验数据与理论计算高度一致。同时指出:装配调试过程的不确定性会造成微膨胀型热开关宏观热特性的小区域波动。本文工作可为后续微膨胀型热开关的结构优化设计、机械加工细化和装调方式改进提供参考。