A knowledge-based system for reactive scheduling decision-making in FMS

This paper describes research into the development of an intelligent simulation environment. The environment was used to analyze reactive scheduling scenarios in a specific flexible manufacturing systems (FMS) configuration. Using data from a real FMS, simulation models were created to study the reactive scheduling problem and this work led to the concept of capturing instantaneous FMS status data as snapshot data for analysis. Various intelligent systems were developed and tested to asses their decision-making capabilities. The concepts of History Logging and expert system learning is proposed and these ideas are implemented into the environment to provide decision-making and control across a FMS schedule lifetime. This research proposes an approach for the analysis of reactive scheduling in an FMS. The approach and system that was subsequently developed was based on the principle of automated intelligent decision-making via knowledge elicitation from FMS status data, together with knowledge base augmentation to facilitate a learning ability based on past experiences.     

Petri net based process scheduling: A model of the control system of flexible manufacturing systems

In this paper, we propose a class of algorithms for the sub-optimal solution of a particular class of problems of process scheduling, particularly focusing on a case study in the area of flexible manufacturing systems (FMSs). The general class of problems we face in our approach is characterized as follows: there is a set of concurrent processes, each formed by a number of temporally related tasks (segments). Tasks are executable by alternate resource sets, different both in performance and costs. Processes and tasks are characterized by release times, due dates, and deadlines. Time constraints are also present in the availability of each resource in resource sets. It has been proven that such a problem does not admit an algorithm for an optimal solution in polynomial time. Our proposed algorithm finds a sub-optimal schedule according to a set of optimization criteria, based on task and process times (earliness, tardiness), and/or time independent costs of resources. Our approach to process scheduling is based on Timed Coloured Petri Nets. We describe the structure of the coordination and scheduling algorithms, concentrating on (i) the general-purpose component, and (ii) the application-dependent component. In particular, the paper focuses on the following issues: (i) theautomatic synthesis of Petri net models of the coordination subsystem, starting from the problem knowledge base; (ii) the dynamic behavior of the coordination subsystem, whose kernel is a High Level Petri net executor, a coordination process based on an original, general purpose algorithm; (iii) the structure of the real-time scheduling subsystem, based on particular heuristic sub-optimal multi-criteria algorithms. Furthermore, the paper defines the interaction mechanisms between the coordination and scheduling subsystems. Our approach clearly distinguishes the mechanism of the net execution from the decision support system. Two conceptually distinct levels, which correspond to two different, interacting implementation modules in the prototype CASE tool, have been defined: theexecutor and thescheduler levels. One of the outstanding differences between these levels is that the executor is conceived as a fast, efficient coordination process, without special-purpose problem-solving capabilities in case of conflicts. The scheduler, on the other hand, is the adaptive, distributed component, whose behavior may heavily depend on the problem class. If the scheduler fails, the executor is, in any case, able to proceed with a general-purpose conflict resolution strategy. Experimental results on the real-time performance of the kernel of the implemented system are finally shown in the paper. The approach described in this paper is at the basis of a joint project with industrial partners for the development of a CASE tool for the simulation of blast furnaces.     

基于浮点型编码策略的差分多目标柔性车间调度优化

运用进化算法求解柔性车间调度问题时,编码的特殊性对进化策略造成的局限制约了算法的搜索能力。为此,提出一种基于浮点型编码策略的差分多目标优化算法。该算法采用基于工序权重的浮点数编码—解码机制,消除了排列组合型编码方式对进化操作带来的约束,运用差分进化策略生成新个体,以提高优秀个体产生的几率,进而保证算法有更好的收敛性。将算法与传统算法及其改进形式在相同测试用例上进行对比,结果表明,本算法在保证收敛性的同时,搜索到更多的非支配个体,体现出更好的分布性。此外,提出了平行决策和等价平行决策的定义,将柔性车间调度模型的研究拓展至决策空间。     

挠性杆弯曲刚度测量的研究

挠性杆是挠性加速度计的关键零件,本文针对挠性杆尺寸细小,难以进行弯曲刚度测量的问题进行了分析。提出了一种新的测量方法,采用视觉传感器实时自动取样并计算挠性杆单端夹持时另一端的下垂角度,进而计算挠性杆的弯曲刚度。理论计算和测试结果表明,该方法可有效解决小尺寸挠性杆弯曲刚度监测中的精度低、操作困难、效率低下等问题。     

机车牵引通风机传动方式选型的可行性探讨

为适应铁路机车现代化的发展,提高机车运用率,简要介绍了机车牵引通风机传动方式选型的可行性。为以后装车运用提供了可靠依据。     

预应力锚索在莲麓一级水电站高边坡防护中的应用

预应力锚索已经是高边坡防护工程中越来越重要的手段,结合莲麓一级水电站预应力锚索在高边坡防护工程中的施工实践,介绍其施工工艺和施工注意事项,可供类似工程参考。     

Solvent‐Assisted Low‐Temperature Crystallization of SnO2 Electron‐Transfer Layer for High‐Efficiency Planar Perovskite Solar Cells

A high‐quality polycrystalline SnO₂ electron‐transfer layer is synthesized through an in situ, low‐temperature, and unique butanol–water solvent‐assisted process. By choosing a mixture of butanol and water as a solvent, the crystallinity is enhanced and the crystallization temperature is lowered to 130 °C, making the process fully compatible with flexible plastic substrates. The best solar cells fabricated using these layers achieve an efficiency of 20.52% (average 19.02%) which is among the best in the class of planar n–i–p‐type perovskite (MAPbI₃) solar cells. The strongly reduced crystallization temperature of the materials allows their use on a flexible substrate, with a resulting device efficiency of 18%.     

18×7类不旋转钢丝绳结构特点

指出18×7类不旋转钢丝绳用途的广泛性,通过对18×7类不旋转钢丝绳结构特点的认识,分析钢丝绳的稳定性及产品缺陷,举例说明提高钢丝绳实物质量的措施和行业内急需解决的技术难题。     

空间柔性双臂机器人的神经网络协调控制

基于对机器人闭链系统运动特性的分析,采用假设模态法及拉格朗日方程建立了自由浮动空间柔性双臂机器人协调操作刚性负载闭链系统的动力学模型,然后采用基于小脑模型的模糊神经网络与非线性PD并行控制的方法对该动力学模型进行轨迹跟踪,并对内力采用积分控制;通过仿真实验比较,该方法比一般的非线性PD控制,在跟踪误差、抗干扰性、鲁棒性方面,都有很大的改善.     

新型芳香二胺的合成及其聚酰亚胺的应用研究

首先通过双酚A和碳酸钾反应得到酚钾盐,与间-二硝基苯反应合成2,2-双[4-(3-硝基苯氧基)苯基]丙烷(3-BNPP),再用水合肼还原得到新型芳香二胺单体2,2-双[4-(3-氨基苯氧基)苯基]丙烷(3-BAPP)。用3-BAPP与多种二酐合成出多种聚酰亚胺,并在二层法挠性覆铜板(2L-FCCL)的应用方面做了一些研究。研究表明其相应的2L-FCCL具有良好的耐锡焊性能和较低的吸水率。