A unified graphical approach to the static analysis of axially loaded structures

The paper presents a unified approach to graphical methods for the static force analysis of axially loaded plane structures. This approach consists of a unified diagram which incorporates both the frame and stress diagrams. This unified representation is applied to a simple Maxwell frame and the authors include a rigorous investigation of the equivalence between the unified diagram and traditional diagrams. The paper shows that traditional diagrams can, in fact, be regarded as particular cases of the unified diagram. The concept of self-reciprocity is introduced and a dual kinematic interpretation of the unified diagram is obtained from a sequence of equivalent diagrams. These diagrams can be obtained in a straightforward manner by changing the force scale factor.     

任意连续梁内力包络图的自动绘制法

根据内力包络图设计梁的断面,可以保证满足安全和经济两方面的要求。但是按传统方法绘制梁的内力包络图手续十分繁琐,对于连续梁之类的多跨梁尤其如此。介绍一种利用奇异函数对连续梁进行力学分析的新方法及其智能分析软件。该方法利用奇异函数与拉普拉斯变换相结合的方法导出连续梁变形和内力的普遍表达式,利用变形和内力的边界条件确定约束反力,然后再在内力普遍表达式的基础上建立一种内力包络图的自动绘制方法。该方法和程序对承受任意恒载和活载、具有任意跨数的连续梁具有普遍的适用性。     

A line-balancing strategy for designing flexible assembly systems

We present a rough-cut analysis tool that quickly determines a few potential cost-effective designs at the initial design stage of flexible assembly systems (FASs) prior to a detailed analysis such as simulation. It uses quantitative methods for selecting and configuring the components of an FAS suitable for medium to high volumes of several similar products. The system is organized as a series of assembly stations linked with an automated material-handling system moving parts in a unidirectional flow. Each station consists of a single machine or of identical parallel machines. The methods exploit the ability of flexible hardware to switch almost instantaneously from product to product. Our approach is particularly suitable where the product mix is expected to be stable, since we combine the hardware-configuration phase with the task-allocation phase.For the required volume of products, we use integer programming to select the number of stations and the number of machines at each station and to allocate tasks to stations. We use queueing network analysis, which takes into account the mean and variance of processing times among different products to determine the necessary capacity of the material-handling system. We iterate between the two analyses to find the combined solution with the lowest costs. Work-in-process costs are also included in the analysis. Computational results are presented.     

Performance Analysis of Flexible Manufacturing Systems with a Single Discrete Material-Handling Device

We present an analytical model for performance prediction of flexible manufacturing systems (FMSs) with a single discrete material-handling device (MHD). This configuration of FMS is significant for many reasons: it is commonly found in industry, it simplifies material-handling control, it is amenable to analytical modeling, and it forms a building block for more complex systems.Standard queueing models are inadequate to analyze this configuration because of the need to take into consideration many nontrivial issues such as state-dependent routing, interference from the MHD, and the analysis of the MHD. To account for state-dependent routing, we develop an iterative method that is built around mean value analysis. To analyze the MHD interference, we use two queueing network models. In the first, we ignore queueing at the MHD but model the interference from the MHD by inflating the station service times. The second network models the queueing for the MHD and estimates the blocking (inflation) times needed for the first model. By iterating between the two networks, we are able to predict the performance of this configuration of FMS. Our analytical estimates are validated against discrete event simulation and shown to be quite accurate for initial system design.     

Binary logic diagrams imply nonunique functionality

Binary logic diagrams (BLDs) are widely used to document the functionality of logic-based control systems. The ambiguous functionality implied by certain BLDs is highlighted by drawing analogies with asynchronous sequential logic systems. Non-deterministic state transitions in these BLDs occur due to the existence of hazard and race conditions or, equivalently, non-unique feedback cut sets. The need for additional specifications to remove this ambiguity is discussed, and recommendations are made to aid in the specification of BLDs with unique functionality.     

基于Voronoi图的快速成型扫描路径生成算法研究

提出一种平面多连通区域的算法 ,该算法对波前传播算法进行了扩展 ,能适用于平面多连通区域。用 VC++实现了平面多连通区域的 Voronoi图算法 ,并应用于立体光固化法快速成型中的扫描路径规划     

Utilization of voronoi diagrams for circularity algorithms

In the past many minimum zone center (MZC) algorithms have been developed. In opposition, many coordinate measuring machines (CMM) still use least-squares center (LSC) algorithms. A MZC algorithm that uses a computational geometry approach through the Voronoi diagrams to determine circularity can be performed with LSC. Both algorithms are compared by scanning the number of points of the set, the circularity value interval, and the workpiece radius. The differences between the results are compared to determine the relationship. The importance of the uncertainty of the machines is then compared with these differences.     

Evaluation of circularity from coordinate and form data using computational geometric techniques

Data for evaluating circularity error can be obtained from coordinate measuring machines or form measuring instruments. In this article, appropriate methods based on computational geometric techniques have been developed to deal with coordinate measurement data and form data. The computational geometric concepts of convex hulls are used, and a new heuristic algorithm is suggested to arrive at the inner hull. Equi-Distant (Voronoi) and newly proposed Equi-Angular diagrams are employed for establishing the assessment features under different conditions. The algorithms developed in this article are implemented and validated with the simulated data and the data available in the literature.     

涡旋压缩机径向随变机构动力学模型研究

对十字滑环防自转机构和带有径向随变机构的涡旋压缩机结构进行了分析和研究，根据其运动特性．建立了偏心套径向随变机构运动简图和引入虚约束以改善受力和机器运转平稳性的偏心套径向随变机构运动简图。依据机构运动简图可进行机器动力学问题的研究分析。     

预测铣削稳定性的隐式Adams方法

针对铣削加工过程中产生的振动现象,提出了一种隐式Adams方法（Implicit Adams method,IAM）来预测铣削加工过程的稳定性。考虑再生颤振的铣削加工动力学方程可以表示为时滞线性微分方程,将刀齿周期可分为自由振动阶段和强迫振动阶段,对强迫振动阶段进行离散,运用IAM方法构建状态传递矩阵,利用Floquet理论,判定系统的稳定性,获得系统的稳定性叶瓣图。Matlab软件仿真结果表明,IAM方法是预测铣削稳定性的一种有效方法。随着离散数的增加,IAM方法的收敛速度要快于一阶半离散法（First-order semi-discretization method,1st-SDM）和二阶全离散法（Second-order full-discretization method,2nd-FDM）,离散数较少的IAM方法能达到离散数较多的1st-SDM方法和2nd-FDM方法的局部离散误差。此外,在单自由度和双自由度动力学模型下,三种方法的稳定性叶瓣图显示,IAM方法预测铣削稳定性的预测精度均好于1st-SDM方法和2nd-FDM方法,计算效率远远高于1st-SDM方法,稍高于2nd-FDM方法。切削试验和仿真结果表明,IAM方法的预测精度和可靠度均好于1st-SDM方法和2nd-FDM方法。     

机液伺服控制系统的综合仿真模型

文章在分析刚性反馈、柔性反馈及综合反馈机液伺服控制系统的基础上，提出了一种综合仿真模型-归一函数方框图。     

派生式CAPP系统工序图的生成方法研究

在CAPP系统研究与开发中,工序简图绘制模式是重要内容之一,通过对工序图的特点及常用生成方法分析,提出了一种基于OLE技术的派生式CAPP系统工序图的生成机理,并给出工作实例。     

Methods of measuring the size and complexity of PLC programs in different logic control design methodologies

Currently there is a wide variety of logic control design methodologies used in industrial logic design. These methodologies include ladder diagrams, function block diagrams, sequential function charts, and flow charts, but driven by a desire for verifiability, academics are developing additional logic control design methodologies, such as modular finite state machines and Petri nets. Using these, important properties of programs can be verified and some logic can be generated automatically from a part plan. The main contribution of this paper is to define methods for measuring programs written in different methodologies, so that the performance of the methodologies can be compared.We demonstrate these methods of measurement using four program samples that perform similar functions on the same machine, written in four logic control design methodologies: ladder diagrams, Petri nets, signal interpreted Petri nets and modular finite state machines.     

Methods of measuring the size and complexity of PLC programs in different logic control design methodologies

Currently there is a wide variety of logic control design methodologies used in industrial logic design. These methodologies include ladder diagrams, function block diagrams, sequential function charts, and flow charts, but driven by a desire for verifiability, academics are developing additional logic control design methodologies, such as modular finite state machines and Petri nets. Using these, important properties of programs can be verified and some logic can be generated automatically from a part plan. The main contribution of this paper is to define methods for measuring programs written in different methodologies, so that the performance of the methodologies can be compared.We demonstrate these methods of measurement using four program samples that perform similar functions on the same machine, written in four logic control design methodologies: ladder diagrams, Petri nets, signal interpreted Petri nets and modular finite state machines.     

派生式CAPP系统工序图的生成方法研究

在CAPP系统研究与开发中，工序简图绘制模式是重要内容之一，通过对工序图的特点及常用生成方法分析，提出了一种基于OLE技术的派生式CAPP系统工序图的生成机理．并给出工作实例。     

Nonlinear forced dynamics of an axially moving viscoelastic beam with an internal resonance

The aim of the study described in this paper is to investigate the forced dynamics of an axially moving viscoelastic beam. The governing equation of motion is obtained via Newton's second law of motion and constitutive relations. The viscoelastic beam material is constituted by the Kelvin–Voigt, a two-parameter rheological model, energy dissipation mechanism, in which material, not partial, time derivative is employed in the viscoelastic constitutive relation. The dimensionless partial differential equation of motion is discretized using Galerkin's scheme with hinged–hinged beam eigenfunctions as the basis functions. The resulting set of nonlinear ordinary differential equations is then solved using the pseudo-arclength continuation technique and a direct time integration. For the system with the axial speed in the sub-critical regime, the response of the system is examined when possessing an internal resonance and when not. By employing a direct time integration, it is shown how the bifurcation diagrams of the system are modified by the presence of the dissipation terms—i.e. by both the time-dependant and steady (due the simultaneous presence of the axial speed and the energy dissipation mechanism) energy dissipation terms. Moreover, the amplitude–frequency responses and bifurcation diagrams of Poincaré maps are presented for several values of the system parameters.     

Predicting of plastic instability and forming limit diagrams

An analytical method is presented for predicting forming limit diagrams achieved during sheet metal forming operations for sheets having planar isotropy. This method is based on the three-phase deformation idealization developed by Johns and Gillis. The Johns–Gillis and Pishbin–Gillis model were restricted to the Hill yield criterion which is not suitable for aluminum alloys (R<1). The present work used the Hosford criterion that is widely used for materials with R<1, in conjunction with the power-law, the Tian–Zhang and the Vocé hardening equations. Results from this analysis are compared with the experimental data for AA3105 and AA8011 aluminum alloys. The results indicate good prediction of limit strains for the two alloys when the Vocé and the Tian–Zhang equations are applied.     

Automatic generation of robotic assembly sequences

This paper describes a programming system capable of automatically generating robotic assembly sequences. It is a generative robotic assembly process planner. A geometric model of the product to be assembled is defined interactively in the feature-based product database. Assembly relationships between components are modelled interactively in the graphical relation diagrams. An initial and a final relation diagram are used to describe the initial and final states of the assembly, respectively. The validity of the physical connections defined in the final relation diagram is checked by analysing the information contained in the feature-based product database A single robotic assembly sequence is generated automatically, using only the relational data defined in the final relation diagram. Subassemblies are generated automatically. The component (or subassembly) to be moved at each step of the sequence is also explicity provided in the assembly-sequence formulation.     

工作流驱动的船舶制造检验过程管理方法的研究

为了提高船舶制造检验工作效率,规范工作过程,保证检验过程信息可追溯,提出了工作流驱动的船舶制造检验过程管理方法。研究分析了船舶制造检验业务流程,利用扩展UML活动图建立了船舶制造检验的工作流模型,并在黄海造船进行了应用实施,实现了船舶制造检验过程的精细化管理。     

PowerCube模块化机器人工作空间计算

以PowerCube模块化机器人为对象,采用D-H法建立机器人运动学数学模型.在比较现有的机器人工作空间求解方法的基础上,分别利用解析法和数值法绘制和计算出机器人的工作空间.将2个图形进行对比,结果表明2种方法所得的结果是一致的.