装配式混凝土结构塔机吊装服务调度研究

随着我国装配率的提高,塔机吊装作业也面临新的挑战,塔式起重机现场的服务调度显得尤为重要。塔式起重机作业效率直接影响工程项目的施工进度与工程成本,同时还会带来施工事故和设备健康等安全隐患。通过把装配式构件任务吊装的时间约束转化为带有交货期的塔机任务,针对带有交货期约束的塔机服务调度问题,解析吊钩行程时间,设计了一种动态搜索启发式算法。通过对工程算例进行求解验证其有效性,试验结果表明所提模型和算法能够在满足物料请求任务时间窗的同时优化作业流程时间,为施工现场塔机作业管理提供决策依据。     

Hybrid of genetic algorithm and simulated annealing for multiple project scheduling with multiple resource constraints

Since scheduling of multiple projects is a complex and time-consuming task, a large number of heuristic rules have been proposed by researchers for such problems. However, each of these rules is usually appropriate for only one specific type of problem. In view of this, a hybrid of genetic algorithm and simulated annealing (GA-SA Hybrid) is proposed in this paper for generic multi-project scheduling problems with multiple resource constraints. The proposed GA-SA Hybrid is compared to the modified simulated annealing method (MSA), which is more powerful than genetic algorithm (GA) and simulated annealing (SA). As both GA and SA are generic search methods, the GA-SA Hybrid is also a generic search method. The random-search feature of GA, SA and GA-SA Hybrid makes them applicable to almost all kinds of optimization problems. In general, these methods are more effective than most heuristic rules. Three test projects and three real projects are presented to show the advantage of the proposed GA-SA Hybrid method. It can be seen that GA-SA Hybrid has better performance than GA, SA, MSA, and some most popular heuristic methods.     

求解随机阻塞批量流水线调度问题的改进人工蜂群算法

针对含有随机加工时间的阻塞批量流水线调度问题,利用蒙特卡洛采样方法,将不确定加工时间的阻塞批量流水线调度问题转化为确定加工时间的阻塞批量调度问题。采用改进的人工蜂群算法,对上述转化后的调度问题进行求解。算法中加入了和声搜索和基于插入操作的局部搜索算子,以改进全局探索和局部开发能力,并将改进的算法应用到阻塞批量调度的24个算例中。仿真实验结果表明,改进的人工蜂群算法能够降低调度中的不确定因素带来的影响,产生高质量的解。     

An optimal scheduling model for ready mixed concrete supply with overtime considerations

The incorporation of overtime considerations in the production and dispatching of ready mixed concrete (RMC) is a complex real world problem. In this research, the authors develop a network flow model for an RMC carrier according to Taiwan's operation situation, that integrates RMC production scheduling and truck dispatching in the same framework, to decide on an optimal RMC supply schedule which also integrates overtime considerations. To build the model, the authors employ a time–space network technique to formulate the production of RMC and the truck fleet flows in the dimensions of time and space. The model is formulated as a mixed integer network flow problem with side constraints. To efficiently solve the problem a solution algorithm incorporating a mathematical programming solver is developed. The network flow model and the solution method are then evaluated using real operating data. The test results show that the model and the solution algorithm could be useful for actual operations.     

基于改进的同步扰动随机逼近算法的聚表二元驱优化

聚表二元驱作为一种提高采收率的有效方法已经被广泛应用于各大油田,为实现聚表二元驱生产效益最大化,从油田实际情况出发,将油田开发的经济效益作为优化目标,选取聚合物与表面活性剂的质量浓度、注入体积、注入时机等参数作为调控变量,并结合改进随机差异化步长的SPSA算法进行优化求解,比较约束与不约束聚合物、表面活性剂使用总量。结果表明:随机差异化步长不仅可以加快算法的运行效率而且能更好地实现全局最优性;当不约束聚合物和表面活性剂使用总量时,在含水率越小时实施聚表二元驱,生产效益越好;当约束聚合物和表面活性剂使用总量时,聚合物和表面活性剂使用总量越小,在含水率越大时实施聚表二元驱生产效益越好。     

An approximation method for resonant response with coupling modes of structures under wind action

Effects of multi-mode coupling should be taken into account in computing the resonant buffeting response of some kinds of flexible structures with low damping and concentrated modes. In this paper, a new concept of “mode coupling factor” for computation of coupling effects between multi-mode resonant responses of the structures is proposed. On the base of the mode coupling factor, a modified SRSS method for computation of the resonant response contributed by multi-modes and their coupling effects of the structures is further raised. The roof structure of Shanghai Southern Railway Station is then taken as the case study to indicate the application and to verify the precision of the mode coupling factor and the modified SRSS method. The computaion results indicate that the mode coupling factor can quantitatively describe the contribution of mode coupling to the resonant response; and the modified SRSS method can make the computation of structural resonant response with consideration of mode coupling effects simpler.     

Framework for city‐scale building seismic resilience simulation and repair scheduling with labor constraints driven by time–history analysis

A city‐scale time–history analysis‐driven framework is proposed for the quantitative evaluation of building seismic resilience and repair scheduling with repair resource constraints. First, a calculation method for the post‐earthquake residual functionality of buildings based on engineering demand parameters is proposed. Second, the repair‐scheduling unit (RSU) concept is proposed for city‐scale repair scheduling. Moreover, two repair priority indices are introduced to evaluate the repair priority of each RSU. Next, the concept of job block is proposed to compute the repair time of an RSU with insufficient repair resources. Subsequently, the workflow of repair simulation is presented to calculate the community recovery curve and resilience index quantitatively. Finally, 68,930 residential buildings of Beijing City's 16 administrative districts are simulated to demonstrate the proposed method. The outcomes of this work are expected to be a useful reference for building seismic resilience evaluation and repair scheduling of communities. Consequently, it could be an aid to pre‐earthquake disaster risk reduction planning and post‐earthquake rapid recovery of building functionalities.     

多工作台石材加工桥式切机研究

本文主要介绍了加工石材的多工作台桥式切机原理、加工工艺和设备结构.多工作台桥式切机主要由四个工作台和一个切割系统及真空机械手构成.工作台主要包括:上料工作台、主工作台、辅助工作台和卸料工作台.切割系统主要包括锯片切割头、横梁机构.真空机械手包括真空吸盘和其运动机构等.该设备带有激光自动扫描系统,可以对板材进行廓形扫描和自动优化排板,采用四个工作台对排板后的板材进行自动切割,实现石材排板切割一体化.     

大跨度桁架几何大变形结构分析的一种数值方法

基于ANSYS平台的二次开发,针对桁架结构几何大变形分析问题提出了一种有效的数值算法。主要思路为:采用两步交替迭代逐步逼近,使平衡状态与变形状态协调、统一,建立并求出变形后的平衡方程及其解;也就是说,首先由已知杆件内力建立计算节点位移的连续方程并求解,然后由已知节点位移建立计算杆件内力的平衡方程并求解,通过多次迭代求得平衡状态与变形状态协调统一的非线性大变形结构分析的精确解。本文方法在整个求解过程中仅需做一次结构分析,此在几何大变形桁架结构的优化设计中更突显其优点。本文方法对扁桁架、大跨度桁架尤其有用。通过编制相应的ANSYS二次开发程序,并由数值算例验证了本文方法的可行性、计算精确和计算效率。     

An optimal condition based maintenance scheduling for metal structures based on a multidisciplinary research approach

Abstract

Latest research findings show that the deterioration of metal coatings results due to complex combination of material and meteorological parameters. The classical maintenance scheduling do not consider complex interface of materials and meteorological parameters to determine optimal maintenance framework. The cost of recoating can be optimised through appropriate selection of coating specifications and maintenance strategy. This research provides a multidisciplinary algorithmic approach to determine cost-effective solutions for recoating. The specifications of red oxide primer coating and structural steel substrate system are considered for simulation analysis. The results show that the appropriate selection of 10% increase in coating thickness based on coating-substrate system specifications resulted in 20–25% reduction in annual patch failures which reduces 5–6% cost of recoating. Furthermore, the proposed model also simulated to compare Patch recoating and Part recoating strategy and algorithm show that the Part recoating is cost-effective as compared to Patch recoating if number of annual patch failure is greater than ‘2’ and area of the part is ‘2×’times larger than the area of the patch. Contrary, the Patch recoating results in low cost if the part area is ‘10×’ times larger than patch area and number of annual patch failures are less than ‘7’.