汽车自适应巡航控制系统硬件在环仿真平台的设计与仿真试验

为了提高自适应巡航控制（ACC）系统的仿真精度,利用实车ACC系统的执行机构建立了硬件在环仿真（HILS）平台。HILS平台由仿真模型和硬件部分组成。仿真模型将运行在dSPACE仿真系统中,包括为了产生雷达模拟信号、ACC控制指令及计算车辆运行状态的雷达模拟器、ACC控制器和车辆模型。硬件部分主要包括电子节气门系统、主动制动系统及其附属的传感器及控制器等。通过串口通信接收来自ACC控制器的指令,HILS平台的硬件可以完成节气门开度和制动压力跟随控制。利用HILS平台进行了不同工况下的ACC仿真试验,仿真结果表明：HILS平台工作状况良好,并可以用于ACC控制器的开发。     

Molecular dynamics simulation of surface segregation, diffusion and reaction phenomena in equiatomic Ni-Al systems

The molecular dynamics method is used to provide fundamental insights into surface segregation, bulk diffusion and alloying reaction phenomena in equiatomic Ni-Al systems. This knowledge can serve as a guide for the search and development of economic routes for controlling microstructure and properties of the intermetallic compound NiAl. This paper gives an overview of recent molecular dynamics simulations in the area along with other theoretical calculations and experimental measurements.     

Molecular dynamics simulation of fast dislocations in copper

Molecular dynamics simulations are used to describe the acceleration and motion of dissociated dislocations in copper to extreme velocities. Stationary dislocations are accelerated either by shear stress or by shear strain rates. Results indicate that dislocations can be accelerated into transonic and supersonic velocities. Stable dislocation motion is found in three distinguished regimes: (i) in a plateau of velocities close to 1.6 km s^?1 in the subsonic regime; (ii) in a narrow range of velocities around 2.6 km s^?1 in the first transonic regime; and (iii) in the second transonic regime with increasing velocities. For large velocities in the second transonic regime and in the supersonic regime, the shear stress is exceeded and dislocation motion is unstable as the crystal loses its mechanical stability. The stacking fault fluctuates around 35 Å in the subsonic regime, but subsequently declines with velocity to less than half the initial value in the second transonic regime. Both the decreasing stacking fault width and the plateau of velocities in the first transonic regime, indicating the existence of a radiation-free state, are in agreement with theoretical predictions.     

Molecular dynamics simulation of an exciton in polyaniline

Adding a weak electron correlation to the extended Ginder–Epstein model for polyaniline, we carried out an adiabatic dynamics simulation for formation of an exciton in a pernigraniline-base polymer, an oxidized form of polyaniline. The results showed: the formation time was ∼50 fs; the correlation speeded up the exciton formation and shortened the exciton radius.     

Interstitial loop strengthening upon deformation in aluminum via molecular dynamics simulations

The formation of prismatic interstitial loops during plastic deformation, as well as their interaction with dislocations, is systematically investigated in aluminum, using molecular dynamics simulations. First, direct dislocation interaction is responsible for producing various types of defects, typically vacancies and their clusters and interstitial loops. Secondly, small interstitial loops act as obstacles to dislocation gliding. When close to each other, a loop either decorates a dislocation with jogs or drags it elastically. The mobility of a dislocation decorated by a loop is significantly reduced. Depending on the relative position of the dislocation and the loop, the Peierls stress can increase several hundred times. The present work shows a complete picture of dislocation–loop interaction with atomic-scale details, which provides reliable information for parameterizing dislocation–debris interactions in constitutive models.     

Coordination policy for production and delivery scheduling in the closed loop supply chain

Coordinating a supply chain necessitates a synchronization strategy for reordering products and a cost-effective production and replenishment cycle time. The aim of this paper is to present an optimization framework for producing and distribution in the supply chains with a cooperating strategy. The main contribution of this paper is to integrate closed loop supply chain with open-shop manufacturing and economic lot and delivery scheduling problem (ELDSP). This integration is applied with the aim of better coordination between the members of the supply chain. This study examines the ELDSP for a multi-stage closed loop supply chain, where each product is returned to a manufacturing center at a constant rate of demand. The supply chain is also characterized by a sub-open-shop system for remanufacturing returned items. Common cycle time and multiplier policies is adopted to accomplish the desired synchronization. For this purpose, we developed a mathematical model in which a manufacturer with an open-shop system purchases raw materials from suppliers, converts them into final products, and sends them to package companies. Given that the ELDSPR is an NP-hard problem, a simulated annealing (SA) algorithm and a biography-based optimization (BBO) algorithm is developed. Two operational scenarios are formulated for the simulated annealing algorithm, after which both the algorithms are used to solve problems of different scales. The numerical results show that the biography-based optimization algorithm excellently performs in finding the best solution to the ELDSPR.     

Physicochemical dynamics of disperse systems in the processes of planet formation

Protection of Metals and Physical Chemistry of Surfaces - The present paper proposes using the method of physicochemical dynamics of disperse systems to study the processes occurring in...     

Molecular dynamics simulation of triple junction migration

We present a molecular dynamics simulation study of the migration of grain boundaries with triple junctions. We have monitored the grain boundary profile, triple junction angles and rate of grain boundary migration with and without triple junctions as a function of grain size, grain misorientation, direction of migration and temperature in a series of configurations designed to ensure steady-state migration. The present results demonstrate that triple junction mobility is finite and can be sufficiently small to limit the rate of grain boundary migration. The drag on grain boundaries due to limited triple junction mobility is important at small grain sizes, low temperature and near high symmetry grain misorientations. This drag limits the rate of grain boundary migration and leads to triple junction angles that differ substantially from their equilibrium value. Simulation data suggest that triple junction drag is much more a factor at low temperature than at high temperature. The triple junction mobility is shown to depend upon the direction of triple junction migration. The present results are in excellent qualitative agreement with experimental observations.     

Modeling of the dynamics of transient liquid films in ternary systems

The presence of a concentration gradient across a thin liquid film leads to the phenomenon of isothermal liquid film migration (LFM). In most cases, the concentration gradient is due to coherency stresses, and the migration of the liquid film results in the relaxation of these stresses. It is also possible to envisage cases in which LFM occurs as a result of chemical solubility differences between stable and metastable phases. Both situations are examined in this contribution with special emphasis on the effect of adding a second solute element to the liquid phase. The kinetics of LFM is examined as a function of the initial liquid concentration and the ratio of the solute diffusion coefficients in a model coherency-driven ternary system. The growth of the Γ₂ inside δ particles in the Zn-Fe-Al system is presented as a possible example of chemically driven LFM. This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University.     

PID算法在西门子PLC模拟量闭环控制中的实现

基于西门子公司S7-200系列PLC，扩展模拟量处理模块，应用PID算法，实现对模拟量的闭环控制，提出了PID控制算法的实现方法和步骤，给出了水箱液位控制应用实例。     

Cyber physical systems for predictive production systems

As disruptive technologies like Industry 4.0 and Internet of Things advance at a breakneck speed, modern manufacturing is ready to embrace the systematic deployment of predictive production systems. The predictive production system is an intelligent manufacturing system where networked assets are equipped with self-awareness to predict, root cause, and reconfigure faulty events automatically. Cyber physical systems are one of the core enabling technologies within which information from all the related perspectives are analyzed and interconnected between physical factory floor and the cyber computational space. It intertwines with smart analytics to comprehend invisible issues for rapid decision making. In this paper, a systematic approach is proposed on how cyber physical systems can be applied to predictive production systems to inject resilience and interoperability so that the productivity of manufacturing can be optimized.     

Valuation of changeable production systems

The introduction of changeable production systems increases the adaptability of factories in an uncertain environment. This paper analyzes the valuation of the economic efficiency of such systems using the real options theory. The developed approach proposes a structured valuation process for selecting options related to production engineering and factory planning. Based on a classification of possible modifications of a production system, options profiles are derived. Considering the existing uncertainty of a company’s environment these profiles may be utilized to identify real options which ought to be included when valuating a technical production system design.     

单晶材料纳米加工的分子动力学模拟研究进展

分子动力学模拟技术是纳米加工研究的重要方法之一。本文概述了经典分子动力学模拟的基本原理和方法,并结合分子动力学模拟的发展历程,从单晶材料纳米加工的物相转变、结构及热力学特性、介质的影响以及加工后亚表面变形层特性这5个方面,综述了分子动力学模拟在单晶材料纳米加工研究中的应用,最后分析了单晶材料分子动力学模拟中存在的一些问题及需要关注的方向。      

Evaluating the substitution risk of production systems in volatile environments

Today’s manufacturing companies are confronted with key challenges such as an increasing individualization and shorter product life cycles. Production systems are to be made resistant to substitutions in order to secure sustainable competitive advantages in such a volatile market environment. A production system runs at risk of being substituted if an alternative production system exists, which is at least equivalent in terms of economic, ecologic, social, and technological criteria with respect to current as well as possible future product programs. The research presented in this paper provides a systematic approach to assess the substitution risk of production systems regarding a current as well as possible future product programs. It comprises a methodology, which allows for a static and dynamic evaluation of production systems based on analytical cost models, scenario creation and real options analysis. By implementing a Monte Carlo simulation, various probability distributions of system parameters can be taken into account. The presented methodology focusses on economic and ecologic aspects. Finally, the methodology is applied to a case study.     

Observation of the critical thickness phenomenon in dislocation dynamics simulation of microbeam bending

Three-dimensional discrete dislocation dynamics simulations of thin aluminium beams in flexure give data in good agreement with critical thickness theory. The yield points (onset of significant plastic deformation) occur near the stress predicted by the theory. In the plastic regime, dislocation densities increase with plastic deformation within the bulk of the beam thickness, while the surface regions are relatively denuded of dislocations. The stress within the beam relaxes in the central part, then rises linearly to the free surfaces. This behaviour is quantitatively in agreement with critical thickness theory with a strain-thickness product for relaxation (plastic deformation) of 0.57 nm.     

Computational simulation of fluid dynamics in a tubular stirred reactor

The flow and concentration fields in a new style tubular stirred reactor were simulated by simulating the fluids dynamics(CFD), in which FLUENT software was used and the standard k-ε model and multiple reference frame(MRF) were adopted. The various values of initial rotating speed and inlet flow rate were adopted. Simulations were validated with experimental residence time distribution(RTD) determination. It is shown that the fluid flow is very turbulent and the flow pattern approaches to the plug flow. The velocity increases from shaft to the end of impeller, and the gradient is enlarged by increasing the rotating speed. Comparison between RTD curves shows that agitation can improve the performance of reactor. As the flow rate increases, the mean residence time decreases proportionally, and the variance of RTD lessens as well. When rotating speed increases to a certain value, the variance of RTD is enlarged by increasing rotating speed, but the mean residence time has no obvious change.     

Numerical simulation of splat formation dynamics in plasma spray forming

Plasma spray forming shows overwhelming advantages in rapid fabricating parts and moulds. The coating microstructure is strongly dependent on the splat morphology and inter-splat contact nature. Therefore, it is necessary to investigate the splat formation mechanism in order to analyze the coating properties. A dynamical process of a single fully molten droplet impacting onto a smooth surface was investigated. At the same time, the interaction between the two molten droplets in the horizontal and vertical directions was also simulated. Finally, the simulations of impact of a molten droplet on an inclined plane and a sharp edge were presented. It is concluded that the relative distance of the two droplets strongly influences the dynamics of the two droplets interaction. The various surface conditions have direct effects on the dynamics of splat formation. When a droplet impacts onto an inclined surface and a sharp edge, the splat morphology changes obviously and the phenomenon of break up is observed.     

Manufacturing systems for the production of seamless-rolled rings

This paper describes the main components of a state-of-the-art manufacturing system for the production of seamless-rolled rings and the research work carried out to provide the relevant technological know-how and database necessary for the production of a wide range of ring-shaped products.

Special emphasis is put on the continuing effort linking research activities with production methods to establish a process of continuous improvement.     

Molecular dynamics simulation of amorphous segregation in Ag-Rh alloys

Molecular dynamics simulation was carried out to investigate the liquid and amorphous microstructures of binary Agx-Rh(100-x) (x = 25, 50, 75 in atom fraction) alloys. Segregation feature of homogeneous interatomic binding of Ag-Rh liquid was found and probed, which can be retained into amorphous solids upon rapid cooling. Homogeneous binding may occur when the difference in the elemental atomic sizes is less than 10%. The icosahedra in liquid before the formation of amorphous state exist in a stable state and the network formed by 1551-clusters in molten alloys would inhibit the crystallization and diffusion of atoms. A higher degree of 1551-clusters will be favorable to form metallic glasses.     

Molecular dynamics simulation on dislocation emission process

A correlative reference model for a computer simulation of molecular dynamics is proposed in this paper. Based on this model, a flexible displacement boundary scheme is naturally introduced and the dislocations emitted from a crack tip are presumed to continuously pass through the border of an inner discrete atomic region to pile up at an outer continuum region. The simulations for a Mo crystal show that the interaction between a crack and emitted dislocations results in the decrease in local stress intensity factor gradually.