龙门式瓷砖自动码垛装置

瓷砖的自动包装线的出现解决了降低劳动强度、提高生产效率的问题,为了节省瓷砖仓储所占空间,往往还需要进行人工的整理,本文设计了一种应用于瓷砖包装线上能够进行水平和竖直混合码垛的装置,整体采用PLC控制,通过人机界面设定参数,即可实现多种平竖混合结构的码垛。速度不低于12包/分钟,完全满足当前效率最高的自动包装线。     

基于重要度的矩形工件优化填充排样算法

大规模矩形件优化排样是一个典型的组合优化问题,属于NP2hard问题。矩形件优化排样已广泛应用于板材切割、瓷砖铺设、服装裁剪等行业。在实际排样工作中发现,决策者对工件的选择不仅要考虑大小、工件费用、铺设利用率等诸多因素,往往还需要考虑颜色、花式、铺设方式等因素。基于这种状况,引入排样属性重要度的概念,提出了基于重要度的矩形工件优化填充排样算法,使用计算机辅助排样。通过实例排样表明了该算法的有效性和实用性。     

瓷砖图像的纹理特征分类研究

在已有的瓷砖图像分类系统中,仅靠颜色特征和简单的纹理边缘信息只能对无花纹的单色砖或简单花纹的瓷砖进行有效分类,对复杂图案的瓷砖存在识别率低的问题。针对此种情况,结合瓷砖图像的灰度共生矩阵和统计几何特征,将这些特征输入支持向量机进行特征分层分类。采用基于径向基核函数和[K]交叉验证法所得到的最优参数构造支持向量机,解决瓷砖纹理特征具有非线性的分类问题。用瓷砖生产线上采集的大量图像进行实验表明,该方法准确率高,分类效果好。     

选矿自动化技术探讨

详细介绍了选矿自动化最重要组成部分即破碎自动化和磨矿分级自动化的优化设计原理,指出随着选矿厂对生产成本、产品质量要求的提高,选矿厂全流程自动控制系统的最优设计势在必行。     

Multi-choice multi-objective mathematical programming model for integrated production planning: a case study

This article develops a multi-choice multi-objective linear programming model in order to solve an integrated production planning problem of a steel plant. The aim of the integrated production planning problem is to integrate the planning sub-functions into a single planning operation. The sub-functions are formulated by considering the capacity of different units of the plant, cost of raw materials from various territories, demands of customers in different geographical locations, time constraint for delivery the products, production cost and production rate at different stages of production process. Departure cost is also considered in the formulation of mathematical programming model. Some of the parameters are decided from a set of possible choices, therefore such parameters are considered as multi-choice type. Multi-choice mathematical programming problem cannot be solved directly. Therefore an equivalent multi-objective mathematical programming model is established in order to find the optimal solution of the problem. Computation of the mathematical programming model is performed with the practical production data of a plant to study the methodology.     

Output strutural controllability: a tool for integrated process design and control

This paper seeks to expose the relative merits of output structural controllability (OSC) as an integrative tool for process design and control. Output structural controllability assists the design engineer in flow-sheet selection, via the elimination of uncontrollable flowsheets, and in control structure synthesis. The qualitative nature of the technique means that it can be performed at the early stages of design, when alternative flowsheets have been proposed, but quantitative design parameters are unknown. As such, OSC may significantly reduce the amount of quantitative modelling required, thereby providing a significant cost saving. Two industrial case studies are examined: a wet grinding circuit and the purification section of an ethylene oxide production plant. In both cases, a control structure is synthesised using a protoype software package developed at The University of Queensland. The control structure designs are seen to be operable recommendations, and similar to those employed by both operating companies; designs which were probably the result of much trial-and-error, many iterations and based on far greater (quantitative) information. The integration of process design and control is a difficult problem. This paper demonstrates that OSC is one tool which may be employed by process design and control engineers to address this problem.     

改进YOLOv5的瓷砖表面缺陷检测

现有瓷砖表面缺陷检测存在识别微小目标缺陷能力不足、检测速度有待提升的问题, 为此本文提出了基于改进YOLOv5的瓷砖表面缺陷检测方法. 首先, 由于瓷砖表面缺陷尺寸偏小的特性, 对比分析YOLOv5s的3个目标检测头分支的检测能力, 发现删除大目标检测头, 只保留中目标检测头和小目标检测头的模型检测效果最佳. 其次, 为了进一步实现模型轻量化, 使用ghost convolution和C3Ghost模块替换YOLOv5s在Backbone网络中的普通卷积和C3模块, 减少模型参数量和计算量. 最后, 在YOLOv5s的Backbone和Neck网络末端添加coordinate attention注意力机制模块, 解决原模型无注意力偏好的问题. 该方法在天池瓷砖瑕疵检测数据集上进行实验, 实验结果表明: 改进后的检测模型的平均精度均值达66%, 相比于原YOLOv5s模型提升了1.8%; 且模型大小只有10.14 MB, 参数量相比于原模型减少了48.7%, 计算量减少了38.7%.     

基于傅里叶变换的随机纹理瓷砖的高精度表面缺陷检测

针对经典缺陷检测算法不能很好地提取随机纹理瓷砖图像的缺陷的问题,提出一种基于傅里叶变换的随机纹理瓷砖表面缺陷高精度检测方法。在此基础上,完成了瓷砖表面缺陷检测硬件系统设计。对采集的瓷砖图像,首先利用傅里叶变换得到频率谱图像,然后研究截止频率参数对滤波的影响,设计最优化滤波器进行滤波,再通过傅里叶逆变换获得重构图像,达到抑制背景纹理信息,加强缺陷区域信息的目的,最后通过阈值化和形态学操作获得缺陷区域。实验结果表明: 本方法对不同的随机纹理瓷砖样本进行缺陷检测的准确率高,在瓷砖缺陷检测中具有较高的实用价值。     

Control of a ceramic tiles cooling process based on water spraying

The control of the surface temperature of ceramic tiles in a real industrial production line is developed. The process consists of a transportation band that carries the hot tiles through a water sprayer whose objective is to reduce its temperature. Two input signals can be modified: the velocity of the transportation band and the flow rate of the sprayer. In order to control the outlet surface temperature, the quantity of water deposited (and hence evaporated) per tile, that is a static function of the velocity and the flow rate, is used as the control input. The inlet temperature has a tile to tile fast pattern variation and a slow average change. First, the experimental identification of the process model is carried out. Then a feedback PI controller based on the measurement of the outlet temperature is then tested, showing a good average tracking, but a poor compensation of the fast variations. An adaptive feedforward control based on the measurement of the inlet and outlet temperatures is developed and also tested in the plant, showing a much better performance, but a higher cost. Finally, a disturbance observer based feedforward control is tested, showing an intermediate performance and cost.     

Assessing environmental impact of small and medium ceramic tile manufacturing enterprises in Thailand

Manufacturing processes employed by small and medium ceramic tile production enterprises in Thailand consume substantial amounts of energy. This study reveals that a small plant uses twice as much energy to produce one square meter of tile than does a medium plant. With the exception of global warming effects, the environmental impacts of a small plant are also larger than those of a medium plant, specifically with respect to ozone depletion, acidification and eutrophication. In addition, the environmental management perspective of the medium plant is based on cost reduction and social necessity. In contrast, the small plant has a negative attitude toward environmental management measures, taking the view that these are not appropriate concerns for small plants. These differing impacts and viewpoints suggest that environmental management in the small and medium plants should apply different approaches. On the one hand, the medium plant should emphasize the accelerated transfer of environmental knowledge to its personnel, while on the other, the owners of the small plant should be made to recognize the environmental impacts of their production activity and products. Additionally, potential benefits that might accrue to the plant owner from environmental impact mitigation should be highlighted.     

基于线阵CCD的瓷砖尺寸在线检测系统的研究

设计了一种基于线阵电荷耦合器件(CCD)的瓷砖尺寸在线检测系统。利用线阵CCD像机对生产线上瓷砖进行扫描,通过适当的图像处理算法得到瓷砖的各项尺寸参数,判别产品是否符合质量要求,并将数据记入数据库以便进行统计分析。用VC++6.0开发了应用软件,用来控制系统的自动运行。实验证明:该系统重复性实验标准差为0.05mm,满足用户需求。     

Computerized materials handling and facility layout design

We are proposing a systematic approach to the design of materials handling (MH) system that includes an algorithm to select the most suitable equipment. Initially, a conveyor system is proposed while determining its association cost. To seek improvements of the system in terms of cost and equipment utilization, the possibility of supplementing or replacing the conveyor with one or more fork-lift trucks (trucks) will be investigated. The final MH system configuration will consist of conveyors and trucks so that total system optimization will be achieved. The literature on MH design is very limited and often this problem is not directly coupled with the layout problem [4]. The model proposed uses the results of a tentatively designed layout and two important characteristics of the materials, namely size and weight. Facility in this paper refers to a manufacturing plant with low to medium production volume in a process oriented environment. Facility layout and materials handling are two highly interdependent problems. The location of departments, the corresponding distances and production rates dictate the cost of MH. On the other hand, MH costs between departments, influence the departmental arrangements [10]. An iterative process is developed between the layout design and MH selection problems.     

Necessity constraint in two plant optimal production problem with imprecise parameters

The purpose of this paper is to present and solve a real-life problem of two plants producing the same item under fuzzy-stochastic environment. Here, an item alongwith random defective units is produced at two different plants situated in different locations under a single management. The rates of demand, production and defectiveness at these places are different. Demands of the item are primarily met locally from the respective plants but if a stock-out situation occurs in a plant, immediately some stock, from the other plant if available, is rushed to the stock-out plant. The demands are known but production rates are unknown, functions of time are taken as control variables. The available budget for the management house is imprecise. The holding, shortage and transportation costs are assumed to be imprecise and represented by fuzzy numbers which are transformed to corresponding interval numbers. Following interval mathematics and nearest interval approximation, the objective function is changed to respective multi-objective functions and thus the single-objective fuzzy problem is reduced to a crisp multi-objective decision making (MODM) problem. The MODM problem is then again transformed to a single crisp objective function with the help of weighted sum method. Using fuzzy relations, the imprecise budget constraint expressed in the form of necessity constraint is transformed into an equivalent crisp one. Then, total cost consisting of production, holding, shortage and transportation (from one plant to another) costs is expressed as an optimal control problem and solved using weighted sum method, the Kuhn-Tucker conditions, Pontryagin’s Optimal Control principle and generalized reduced gradient (GRG) technique. The model has been illustrated by numerical data. The optimum results are presented in both tabular and graphical forms.     

The economic production lot size model extended to include more than one production rate

We study an extension of the economic production lot size model, where more than one production rate can be used during a cycle. Moreover, the production rates, as well as their corresponding runtimes are decision variables. We decompose the problem into two subproblems. First, we show that all production rates should be chosen in the interval between the demand rate and the production rate which minimizes unit production costs, and should be used in an increasing order. Then, given the production rates, we derive closed‐form expressions for all optimal runtimes as well as the minimum average cost. This analysis reveals that it is the size of the setup cost that determines the need for being able to use several production rates. We also show how to derive a near‐optimal solution of the general problem.     

Integrated pulp and paper mill planning and scheduling

This article describes a real-world production planning and scheduling problem occurring at an integrated pulp and paper mill (P&P) which manufactures paper for cardboard out of produced pulp. During the cooking of wood chips in the digester, two by-products are produced: the pulp itself (virgin fibers) and the waste stream known as black liquor. The former is then mixed with recycled fibers and processed in a paper machine. Here, due to significant sequence-dependent setups in paper type changeovers, sizing and sequencing of lots have to be made simultaneously in order to efficiently use capacity. The latter is converted into electrical energy using a set of evaporators, recovery boilers and counter-pressure turbines. The planning challenge is then to synchronize the material flow as it moves through the pulp and paper mills, and energy plant, maximizing customer demand (as backlogging is allowed), and minimizing operation costs. Due to the intensive capital feature of P&P, the output of the digester must be maximized. As the production bottleneck is not fixed, to tackle this problem we propose a new model that integrates the critical production units associated to the pulp and paper mills, and energy plant for the first time. Simple stochastic mixed integer programming based local search heuristics are developed to obtain good feasible solutions for the problem. The benefits of integrating the three stages are discussed. The proposed approaches are tested on real-world data. Our work may help P&P companies to increase their competitiveness and reactiveness in dealing with demand pattern oscillations.     

Optimal semi-oblique tiling

For 2D iteration space tiling, we address the problem of determining the tile parameters that minimize the total execution time on a parallel machine. We consider uniform dependency computations tiled so that (at least) one of the tile boundaries is parallel to the domain boundaries. We determine the optimal tile size as a closed form solution. In addition, we determine the optimal number of processors and also the optimal slope of the oblique tile boundary. Our results are based on the BSP model, which assures the portability of the results. Our predictions are justified on a sequence global alignment problem specialized to similar sequences using Fickett's k-band algorithm, for which our optimal semi-oblique tiling yields an improvement of a factor of 2.5 over orthogonal tiling. Our optimal solution requires a block-cyclic distribution of tiles to processors. The best one can obtain with only block distribution (as many authors require) is three times slower. Furthermore, our best running time is within 10 percent of the "predicted theoretical peak" performance of the machine!.     

An adaptive guidance approach for the heuristic solution of a minimum multiple trip vehicle routing problem

One of the most important problems in combinatorial optimization is the well-known vehicle routing problem (VRP), which calls for the determination of the optimal routes to be performed by a fleet of vehicles to serve a given set of customers. Recently, there has been an increasing interest towards extensions of VRP arising from real-world applications. In this paper we consider a variant in which time windows for service at the customers are given, and vehicles may perform more than one route within a working shift. We call the resulting problem the minimum multiple trip VRP (MMTVRP), where a “multiple trip” is a sequence of routes corresponding to a working shift for a vehicle. The problem objective is to minimize the overall number of the multiple trips (hence the size of the required fleet), breaking ties in favor of the minimum routing cost.     

An economic dispatch algorithm of combined cycle units

This paper presents a method to solve the economic dispatch (ED) problem for thermal unit systems involving combined cycle (CC) units. The ED problem finds the optimal generation of each unit in order to minimize the total generation cost while satisfying the total demand and generating-capacity constraints. A CC unit presents multiple configurations or states, each state having its own unique cost curve. Therefore, in performing ED, we need to be able to shift between these cost curves. Moreover, the cost curve is not convex for some of these states. Hence, ED becomes a non-convex optimization problem, which is difficult to solve by conventional methods. In this paper we present a new technique, developed to find the global solution, that is based on the calculation of the infimal convolution. The paper includes the results for a case test and we compare our solution with other techniques.     

基于PLC的瓷砖平整度在线检测系统研究

为实现瓷砖平整度的自动在线检测及分级,设计了基于PLC、组态软件和激光位移传感器的瓷砖平整度实时检测分级系统。系统由传送、检测和分级三部分组成。该检测系统采用光学三角法检测技术,通过编码器及PLC的高速计数器功能对移动中的待检测瓷砖的采样位置进行精确定位,使用激光位移传感器对瓷砖表面进行信息采集,经AD转换后在PLC内部按照特定的算法进行平整度运算,以PLC为核心实现瓷砖的分级处理和对设备的整体控制。实验表明该检测系统高效、稳定、可靠。瓷砖平整度检测精度为±0.1 mm,多次同方向检测精度为±0.05 mm,检测速度为每分钟40片,检测准确度可达到95%以上,适用于当前瓷砖生产过程的质量控制。     

A volume flexible economic production lot-sizing problem with imperfect quality and random machine failure in fuzzy-stochastic environment

An “economic production lot size” (EPLS) model for an item with imperfect quality is developed by considering random machine failure. Breakdown of the manufacturing machines is taken into account by considering its failure rate to be random (continuous). The production rate is treated as a decision variable. It is assumed that some defective units are produced during the production process. Machine breakdown resulting in idle time of the respective machine which leads to additional cost for loss of manpower is taken into account. It is assumed that the production of the imperfect quality units is a random variable and all these units are treated as scrap items that are completely wasted. The models have been formulated as profit maximization problems in stochastic and fuzzy-stochastic environments by considering some inventory parameters as imprecise in nature. In a fuzzy-stochastic environment, using interval arithmetic technique, the interval objective function has been transformed into an equivalent deterministic multi-objective problem. Finally, multi-objective problem is solved by Global Criteria Method (GCM). Stochastic and fuzzy-stochastic problems and their significant features are illustrated by numerical examples. Using the result of the stochastic model, sensitivity of the nearer optimal solution due to changes of some key parameters are analysed.