Disassembly sequence generation: A Petri net based heuristic approach

The generation of a set of optimal or near-optimal disassembly sequences is an important task associated with the study of disassembly planning. This task encapsulates actions at the required disassembly depth to reach maximum net revenue while satisfying economic constraints. The Petri net modelling, combined with heuristic search procedures developed in this study, offers an efficient procedure for disassembly sequence generation. The heuristic generates and searches a partial reachability graph to arrive at an optimal or near-optimal disassembly sequence based on the firing sequence of transitions of the Petri net model. The proposed methodology reduces the search space in two areas: (1) pruning the disassembly tree (DT) and, (2) selective tracking of the reachability graph. The efficacy of the proposed methodology is demonstrated by using two examples from the literature.     

A general search sequencing rule for job shop sequencing

This paper sets out, an approach to the job shop sequencing problem by determining the priority of a job from a linear combination of the basic quantities of operation times and due date. This achieves a simple yet unified format. Furthermore, since these basic quantities are used in fixed linear combinations in the majority of well-known simple heuristics, the rule outlined in the paper is capable of representing such heuristics as special cases within its framework. A performance function is used to assess the effectiveness of the rule and no limitations are imposed on its structure. The form of the variable priority rule is then determined by a computer search routine basing its decisions on the values of the performance function. This overall approach to job shop sequencing we term the search sequencing rule (SSR).     

Disassembly line in product recovery

There are several situations in a product recovery environment where products may be disassembled for economical and regulatory reasons. The disassembly line is perhaps the most suitable setting for disassembly of large products (consisting of numerous components) as well as small products received in large quantities. This paper discusses the importance of a disassembly line in product recovery. The objective of the disassembly line is to utilize the available resources as efficiently as possible while meeting the demand for recovered parts. However, there are many complicating matters that need to be considered to create an efficient disassembly line. Our primary goal is to discuss these issues and provide a better understanding of the complications and their effects on the disassembly line. We also demonstrate how some important factors in disassembly can be accommodated to balance a paced disassembly line by modifying the existing concept of assembly line balancing. An example is presented to illustrate the approach.     

Software reliability prediction: A survey

Softwares play an important role in controlling complex systems. Monitoring the proper functioning of the components of such systems is the principal role of softwares. Often, a petite fault in one of the subsystems may cause irreparable damages; therefore, it is of great importance to be able to predict software faults and estimate the reliability of softwares. In this survey, we present a classification of various methods proposed in the literature to predict software reliability. This study summarizes the results of more than 200 research papers in the field. We also discuss the challenges involved in prediction methods along with proposed partial solutions (i.e., Bayesian methods) to improve the accuracy of such predictions. Moreover, we review numerous evaluation measures introduced so far to assess the performance of prediction models, the datasets they are based on, and also the results they yield.     

Automated manufacturability analysis: A survey

In the market-place of the 21st century, there is no place for traditional over-the-wall communications between design and manufacturing. In order to design it right the very first time, designers must ensure that their products are both functional and easy to manufacture. Software tools have had some successes in reducing the barriers between design and manufacturing. Manufacturability analysis systems are emerging as one such tool — enabling identification of potential manufacturing problems during the design phase and providing suggestions to designers on how to eliminate them.In this paper, we provide a survey of current state-of-the-art automated manufacturability analysis. We present the historical context in which this area has emerged and outline characteristics to compare and classify various systems. We describe the two dominant approaches to automated manufacturability analysis and overview representative systems based on their application domain. We describe support tools that enhance the effectiveness of manufacturability analysis systems. Finally, we attempt to expose some of the existing research challenges and future directions.     

Digital distance geometry: A survey

Digital distance geometry (ddg) is the study of distances in the geometry of digitized spaces. This was introduced approximately 25 years ago, when the study of digital geometry itself began, for providing a theoretical background to digital picture processing algorithms. In this survey we focus our attention on theddg of arbitrary dimensions and other related issues and compile an up-to-date list of references on the topic.     

Disassembly of nanodiscs with cholate

Nanodiscs are protein-lipid particles that furnish a nanometer-sized membrane environment for the investigation of membrane proteins. Nanodiscs assemble spontaneously upon the removal of cholate from an initial mixture of cholate, lipids, and engineered amphipathic proteins. A combined experimental-computational approach is applied here to study the disassembly of nanodiscs through the addition of cholate to preformed particles. For this purpose, small-angle X-ray scattering experiments and coarse-grained molecular dynamics simulations were performed and compared. The study offers a detailed view of nanodisc dynamics.     

Data mining in e-commerce: A survey

Data mining has matured as a field of basic and applied research in computer science in general and e-commerce in particular. In this paper, we survey some of the recent approaches and architectures where data mining has been applied in the fields of e-commerce and e-business. Our intent is not to survey the plethora of algorithms in data mining; instead, our current focus being e-commerce, we limit our discussion to data mining in the context of e-commerce. We also mention a few directions for further work in this domain, based on the survey.     

包装容器的拆卸设计问题

给出了一种新的包装容器设计方法——拆却设计，该方法针对回收处理过程存在的环境污染及资源浪费等问题提出了面向回收利用的包装容器设计改进方法。     

基于模糊推理的不确定环境下拆卸工艺规划

回收产品因磨损等原因其结构和质量会发生改变,拆卸序列规划存在不确定性,拆卸前很难确定产品最优拆卸序列。首先建立一个模糊拆卸Petri网模型表示产品可行拆卸序列和拆卸过程存在的不确定信息,为降低产品质量和拆卸能力的不确定性对拆卸序列优化的影响,建立一个自适应的模糊推理系统,利用模糊推理和反馈学习的方法对产品各拆卸步骤的成本进行预测,然后通过计算不同拆卸序列下拆卸的收益来得到产品最优拆卸序列,最后通过算例证明了方法的有效性。     

Disassembly of 2D Vertical Heterostructures

As one of the most widely discussed fields, the assembly of nanomaterials has always been extensively studied. However, its inverse process, namely disassembly, is still limited in the ambit of biomolecules. Specifically, in the emerging 2D research field, disassembly still remains unexplored. Inspired by the disassembly of DNA molecules via breaking intermolecular hydrogen bonds, the disassembly of 2D vertical heterostructures (2DVHs) is first achieved through the weakening of the interlayer van der Waals interactions. As a demonstration, ReS₂/WS₂ VHs is successfully disassembled into individual building blocks. Density functional theory calculations are performed to study the disassembly of the 2DVHs, which simulate that 2DVHs are first activated by the disassembly promoters and then disassembled with weakened interlayer van der Waals interactions. Such a disassembly process demonstrates that it has great potential to be expanded as a general strategy to achieve the disassembly of other 2D superstructures.     

Open-pit block sequencing optimization: A mathematical model and solution technique

This study presents a comprehensive mathematical formulation model for a short-term open-pit mine block sequencing problem, which considers nearly all relevant technical aspects in open-pit mining. The proposed model aims to obtain the optimum extraction sequences of the original-size (smallest) blocks over short time intervals and in the presence of real-life constraints, including precedence relationship, machine capacity, grade requirements, processing demands and stockpile management. A hybrid branch-and-bound and simulated annealing algorithm is developed to solve the problem. Computational experiments show that the proposed methodology is a promising way to provide quantitative recommendations for mine planning and scheduling engineers.     

Disassembly line balancing using linear physical programming

Disassembly is the separation of a product into its constituent parts in a systematic way. It has gained importance recently due to its vital importance in product recovery. Cost-effective implementation of disassembly operation has a direct impact on the profitability of product recovery activities (recycling, remanufacturing etc.). Although it is possible to carry out disassembly operations in a disassembly station or in a disassembly cell, the highest productivity is achieved in a disassembly line. The output of a disassembly line can be maximised only if the line is balanced. A linear physical programming-based disassembly line balancing method is proposed in this study. This method was used to balance a mixed-model disassembly line and the effectiveness of the method was illustrated by analysing the results.     

论产品拆解与绿色设计方法问题

基于产品设计资料,引入产品结构树型图、产品可拆解性和能源回收指数等概念,评估了产品的可拆解性和能源回收性;构建了合并材料和整合产品功能单元2种绿色优化设计方法。以四川绵阳某企业B型超声仪器为例,通过优化设计前后产品零部件数量、拆解步数、拆解时间和能源回收指数的对比,验证了该方法的有效性。     

Disassembly line design with multi-manned workstations: a novel heuristic optimisation approach

As the first and the most time consuming step of product recovery, disassembly is described as the systematic separation of constituent parts from end-of-life products through a series of operations. In this context, designing and balancing disassembly lines are critical in terms of the efficiency of product recovery. Recent research on disassembly line balancing (DLB) has focused on classical stations where only one worker is allocated. However, such a line results in larger space requirement and longer disassembly lead time. In this paper, disassembly line balancing problem (DLBP) with multi-manned stations is introduced to the relevant literature as a solution to overcome these disadvantages. A mixed integer linear programming (MILP) model and two novel framework heuristic algorithms are developed to minimise the number of workers and workstations. MILP model has been applied to a dishwasher disassembly system. The application results indicate the superiority of establishing multi-manned stations over classical disassembly system design with single-worker stations with shorter disassembly lead time (80.9%) and line length (60.2%). Moreover, the proposed heuristics have been compared on newly generated test problems (instances) for DLBP. The results validate that the heuristics provide acceptable solutions in a reasonable amount of time even for large-sized problems.     

Disassembly sequence plan generation using a branch-and-bound algorithm

This paper presents an approach to generate disassembly sequence plans (DSP) automatically for product recycling and remanufacturing. An algorithm is defined first that generates a geometrically based disassembly precedence matrix (DPM) from a CAD drawing of the product. The DPM is then used to generate a hierarchical disassembly tree (HDT) that represents the feasible DSP. Generation of the HDT, i.e. generation of all feasible DSP, is NP-complete. Thus, to keep the size of the HDT manageable, the branching and bounding processes are controlled using two user-defined variables. The first, w , controls the enumeration of the HDT, while the second, v, controls the bounding procedure in the HDT along with an evaluation function. The evaluation function incorporates tool changes, changes in direction of movement during disassembly along with individual part characteristics (e.g. high-valued parts, parts with hazardous content, etc.). The resulting HDT is called the reduced HDT (RHDT) since it only represents as many (near-) optimum DSP as the size of v. Experimental results demonstrate the applicability and effectiveness of the methodology.     

糖果包装机虚拟拆装碰撞检测研究

目的 为了提高虚拟装配系统中碰撞检测的效率,提出以AABB包围盒粗检测和深度图细检测的碰撞检测方法。方法 首先利用SolidWorks软件建立BZ350糖果包装机模型,以STL格式导入到引擎中,通过对零件先建立AABB包围盒做粗检测后,分别对2个零件获取对应的深度图,使用OpenCV对2张深度图相叠加,根据叠加后像素值的大小来判断零件是否发生了碰撞。结果 实验表明,当叠加后深度值小于100的数量占所有深度值不为0的数量的比例大于86.2736%时,即可认定两零件发生碰撞。结论 对比传统检测算法,此算法在保证了检测速度和检测精度的前提下,对复杂模型的检测具有优势,并且保证了运行的速度在40帧/s以上的流畅运行。     

Adaptive nanopores: A bioinspired label-free approach for protein sequencing and identification

Single molecule protein sequencing would tremendously impact in proteomics and human biology and it would promote the development of novel diagnostic and therapeutic approaches.However,its technological realization can only be envisioned,and huge challenges need to be overcome.Major difficulties are inherent to the structure of proteins,which are composed by several different amino-acids.Despite long standing efforts,only few complex techniques,such as Edman degradation,liquid chromatography and mass spectroscopy,make protein sequencing possible.Unfortunately,these techniques present significant limitations in terms of amount of sample required and dynamic range of measurement.It is known that proteins can distinguish closely similar molecules.Moreover,several proteins can work as biological nanopores in order to perform single molecule detection and sequencing.Unfortunately,while DNA sequencing by means of nanopores is demonstrated,very few examples of nanopores able to perform reliable protein-sequencing have been reported sofar.Here,we investigate,by means of molecular dynamics simulations,how a re-engineered protein,acting as biological nanopore,can be used to recognize the sequence of a translocating peptide by sensing the MshapeH of individual amino-acids.In our simulations we demonstrate that it is possible to discriminate with high fidelity,9 different amino-acids in a short peptide translocating through the engineered construct.The method,here shown for fluorescence-based sequencing,does not require any labelling of the peptidic analyte.These results can pave the way for a new and highly sensitive method of sequencing.