Scheduling algorithms for remanufacturing systems with parallel flow-shop-type reprocessing lines

This study considers a scheduling problem for remanufacturing systems in which end-of-life products are separated into their major components at a disassembly workstation, each of them is reprocessed at its dedicated flow-shop-type reprocessing line with serial workstations, and finally, the reprocessed components, together with new components if required, are reassembled into remanufactured products at a reassembly workstation. Among various system configurations, we focus on the one with parallel flow-shop-type reprocessing lines since it is a typical remanufacturing configuration. The problem is to determine the sequence of products to be disassembled, the sequence of components to be reprocessed at each workstation of flow-shop-type reprocessing lines and the sequence of products to be reassembled for the objective of minimising the total flow time. An integer programming model is developed to represent the problem mathematically, and then, three types of heuristics, i.e. priority rule-based heuristic, Nawaz–Enscore–Ham-based heuristic and iterated greedy algorithm, are proposed due to the problem complexity. To show the performances of the heuristics, a series of computational experiments were done on various test instances, and the results are reported.     

Multi-product inventory planning with downward substitution, stochastic demand and setup costs

In this paper we consider a single period multi-product inventory problem with stochastic demand, setup cost for production, and one-way product substitution in the downward direction. We model the problem as a two-stage integer stochastic program with recourse where the first stage variables determine which products to produce and how much to produce, and the second stage variables determine how the products are allocated to satisfy the realized demand. We exploit structural properties of the model and utilize a combination of optimization techniques including network flow, dynamic programming, and simulation-based optimization to develop effective heuristics. Through a computational study, we evaluate the performance of our heuristics by comparison with the corresponding optimal solution obtained from a large scale mixed integer linear program. The computational study indicates that our solution methodology can be very effective (98.8% on average) and can handle industrial-sized problems efficiently. We also provide several new qualitative insights on issues such as the effect of demand variance and cost parameters on the optimal number of products setup, the amount produced or inventoried, and the benefits of allowing substitution.     

Reliability allocation problem in a series–parallel system

In order to improve system reliability, designers may introduce in a system different technologies in parallel. When each technology is composed of components in series, the configuration belongs to the series–parallel systems. This type of system has not been studied as much as the parallel–series architecture. There exist no methods dedicated to the reliability allocation in series–parallel systems with different technologies. We propose in this paper theoretical and practical results for the allocation problem in a series–parallel system. Two resolution approaches are developed. Firstly, a one stage problem is studied and the results are exploited for the multi-stages problem. A theoretical condition for obtaining the optimal allocation is developed. Since this condition is too restrictive, we secondly propose an alternative approach based on an approximated function and the results of the one-stage study. This second approach is applied to numerical examples.     

How do the internet technological developments shift the consumption pattern of paper products? Evidence from China

Using a monthly data between 2008 and 2019, this study investigated how the development of the Internet technologies has shaped the consumer consumption pattern of different types of paper products in China during this period. In detail, this study covers four major types of paper products in the Chinese market: newsprint, printing paper, household paper, and packaging paper. The developments of Internet technologies were decomposed into two aspects: the communication technology (CT) and the software platform technology (PT). Granger causality analysis was employed to determine whether the consumption pattern of paper products was affected by the development of the Internet. Furthermore, impulse-response analyses were utilized to measure how the consumption pattern of each paper product was shaped by the development of each aspect of Internet technologies, i.e., CT or PT. The empirical results suggested that the Internet developments are causing the consumption patterns shifts of all four paper products. Specifically, the consumptions of newsprint and printing paper were driven by both CT and PT. However, the consumptions of packaging paper and household paper were driven by the PT only. Compared to the development of CT, we found that the quick evolution of PT plays a more significant role in shifting people's consumption of paper products in China. The empirical results revealed by this study could provide valuable economics and policy implications to both academia and relevant industries.     

A Quantum-Dot Array as Model for Copper-Oxide Superconductors: A Dedicated Quantum Simulator for the Many-Fermion Problem

Quantum systems with a large number of fermionic degrees of freedom are intractable by quantum simulations. In this paper we introduce the concept of a dedicated quantum simulator (DQS) which is an artificial system of quantum dots whose Hamiltonian maps exactly to the original many fermion problem. While the universal quantum simulator (UQS) introduced by Feynman in 1982 can simulate any quantum mechanical many-body problem, a DQS can only solve a particular many body problem. Our concept of the dedicated quantum simulator is not a quantum computer but rather a quantum analog device, dedicated to a particular quantum computation. As an example, we consider the system of the CuO plane in the copper-oxide superconductors and we propose an array of electrostatically confined quantum dots to be used as its dedicated quantum simulator. We show that this dedicated device can be used to image stripe formation as a function of the electron doping using electric force microscopy. We argue that such a dedicated quantum simulator may be easier to realize in the future compared to a general purpose quantum computer.     

Allocating work in process in a multiple-product CONWIP system with lost sales

To operate a multiple-product manufacturing system under a CONWIP control policy, one must decide how to assign kanbans to products. With a fixed total number of kanbans in a competitive environment, the goal is to determine their allocation to product types in order to minimize lost sales equitably. In particular, we consider systems in which the products may make multiple visits to the same station with a different processing time distribution on each repeat visit. With a fixed number of kanbans dedicated to each product, the system is modeled as a multiple-chain multiple-class closed queuing network. A nonlinear program simultaneously provides an approximate performance evaluation and optimizes the allocation of kanbans to product types. In numerical examples, the allocations identified are similar to those obtained by exhaustive enumeration with simulation, but frequently differ significantly from a naïve allocation according to demand rates. A variant of the model that minimizes the total work-in-process to achieve specified throughput targets yields results similar to a previous heuristic method.     

Identifying Counterexamples Without Variability in Software Product Line Model Checking

Product detection based on state abstraction technologies in the software product line (SPL) is more complex when compared to a single system. This variability constitutes a new complexity, and the counterexample may be valid for some products but spurious for others. In this paper, we found that spurious products are primarily due to the failure states, which correspond to the spurious counterexamples. The violated products correspond to the real counterexamples. Hence, identifying counterexamples is a critical problem in detecting violated products. In our approach, we obtain the violated products through the genuine counterexamples, which have no failure state, to avoid the tedious computation of identifying spurious products dealt with by the existing algorithm. This can be executed in parallel to improve the efficiency further. Experimental results show that our approach performs well, varying with the growth of the system scale. By analyzing counterexamples in the abstract model, we observed that spurious products occur in the failure state. The approach helps in identifying whether a counterexample is spurious or genuine. The approach also helps to check whether a failure state exists in the counterexample. The performance evaluation shows that the proposed approach helps significantly in improving the efficiency of abstraction-based SPL model checking.     

Manufacturing process problem analysis using monte carlo simulation

The Monte Carlo simulation technique is already well known and used to analyse complex problems. In this paper we present its use to determine the impact of a manufacturing process problem on output quality. During production start-up on an automated manufacturing line a process problem escaped detection for a short period. There was the need to know its impact on output quality in order to provide an appropriate corrective action strategy for the products already in the warehouse and ready for shipment to selected users.     

Determining inventory levels in a CONWIP controlled job shop

We extend the concept of CONWIP control to a job shop setting, in which multiple products with distinct routings compete for the same set of resources. The problem is to determine the fixed overall WIP level and its allocation to product types (WIP mix) to meet a uniformly high customer service requirement for each product type. We formulate an optimization problem for an open queuing network model in which customer orders pull completed products from the system. Then, assuming heavy demand, we derive a throughput target for each product type in a closed queuing network and provide a simple heuristic to find a minimum total WJP and WIP mix that will achieve an operating throughput close to this target. In numerical examples, the WIP mix suggested by this approach achieves the customer service requirement with a relatively low total WIP     

Tackling perishability in multi-level process industries

The classical multi-level lot-sizing and scheduling problem formulations for process industries rarely address perishability issues, such as limited shelf lives of intermediate products. In some industries, ignoring this specificity may result in severe losses. In this paper, we start by extending a classical multi-level lot-sizing and scheduling problem formulation (MLGLSP) to incorporate perishability issues. We further demonstrate that with the objective of minimising the total costs (purchasing, inventory and setup), the production plans generated by classical models are often infeasible under a setting with perishable products. The model distinguishes different perishability characteristics of raw materials, intermediates and end products according to various industries. Finally, we provide quantitative insights on the importance of considering perishability for different production settings when solving integrated production planning and scheduling problems.     

Optimizing production smoothing decisions via batch selection for mixed-model just-in-time manufacturing systems with arbitrary setup and processing times

This paper is concerned with the production smoothing problem that arises in the context of just-in-time manufacturing systems. The production smoothing problem can be solved by employing a two-phase solution methodology, where optimal batch sizes for the products and a sequence for these batches are specified in the first and second phases, respectively. In this paper, we focus on the problem of selecting optimal batch sizes for the products. We propose a dynamic programming (DP) algorithm for the exact solution of the problem. Our computational experiments demonstrate that the DP approach requires significant computational effort, rendering its use in a real environment impractical. We develop three meta-heuristics for the near-optimal solution of the problem, namely strategic oscillation, scatter search and path relinking. The efficiency and efficacy of the methods are tested via a computational study. The computational results show that the meta-heuristic methods considered in this paper provide near-optimal solutions for the problem within several minutes. In particular, the path relinking method can be used for the planning of mixed-model manufacturing systems in real time with its negligible computational requirement and high solution quality.     

肉品保鲜包装材料与新技术研究进展

目的 对现阶段肉品保鲜包装材料及相应的包装新技术进行研究总结,以期为肉类食品保鲜提供一定参考。方法 通过查阅国内外相关文献,总结当前肉类食品使用的包装材料及包装技术,综述真空包装、气调包装、智能包装的研究进展,分析其存在的优点和不足,并对其未来发展趋势进行展望。结论 包装可对肉品起到直接的保护作用,在一定程度上延长了肉品的货架期。新型包装材料及配套包装技术的应用对提升肉品质量和安全至关重要。未来更加安全高效便捷的新型肉类食品包装材料及不同包装技术间的结合会成为行业发展的大趋势。     

A two-stage robust programming approach to demand-driven disassembly planning for a closed-loop supply chain system

The closed-loop supply chain system, which integrates forward and reverse logistics, is a desirable policy for retaining recoverable resources and extending the life cycles of products. In this study, we propose a methodology to contend with a demand-driven disassembly planning problem under a closed-loop supply chain system. A two-stage robust programming model is developed correspondingly, such that multiple products with a hierarchical product's structure are disassembled to satisfy uncertain demands in multiple periods. The objective of the model is to determine a robust decision for recycle volume and timing of each type of end-of-life (EOL) product, as well as recovery strategies. The results provide two-stage decisions by considering future scenarios of periodic demands at the beginning of a planning horizon. The first-stage decision is to determine a compromise solution that is close to the optimal solution for every scenario while retaining a certain level of infeasibility of constraints, such as unsatisfied demand. Afterward, when the outcome of a scenario has been realised, the second-stage decision, such as, inventory volume, is conducted to become a buffer for mitigating uncertain impacts. Furthermore, the computational results confirm the trade-off relationship between solution robustness and model robustness, which are core results of the robust model apart from expected profit. The different types of decision makers’ preferences toward risk can be accounted for to determine a compromise robust solution.     

Industrial waste recycling strategies optimization problem: mixed integer programming model and heuristics

Manufacturers have a legal accountability to deal with industrial waste generated from their production processes in order to avoid pollution. Along with advances in waste recovery techniques, manufacturers may adopt various recycling strategies in dealing with industrial waste. With reuse strategies and technologies, byproducts or wastes will be returned to production processes in the iron and steel industry, and some waste can be recycled back to base material for reuse in other industries. This article focuses on a recovery strategies optimization problem for a typical class of industrial waste recycling process in order to maximize profit. There are multiple strategies for waste recycling available to generate multiple byproducts; these byproducts are then further transformed into several types of chemical products via different production patterns. A mixed integer programming model is developed to determine which recycling strategy and which production pattern should be selected with what quantity of chemical products corresponding to this strategy and pattern in order to yield maximum marginal profits. The sales profits of chemical products and the set-up costs of these strategies, patterns and operation costs of production are considered. A simulated annealing (SA) based heuristic algorithm is developed to solve the problem. Finally, an experiment is designed to verify the effectiveness and feasibility of the proposed method. By comparing a single strategy to multiple strategies in an example, it is shown that the total sales profit of chemical products can be increased by around 25% through the simultaneous use of multiple strategies. This illustrates the superiority of combinatorial multiple strategies. Furthermore, the effects of the model parameters on profit are discussed to help manufacturers organize their waste recycling network.     

冰晶对冻结水产品品质的影响及抑制措施

目的为进一步优化水产品的冻结方式、改善水产品在冻藏期间的品质提供理论参考。方法介绍冰晶对水产品中蛋白质、脂质、质构特性,以及色泽、气味等感官品质的影响,冻结时形成的体积大且分布不均匀的冰晶会对水产品品质造成不可逆转的破坏。综述在水产品冻结领域中能够有效改善冰晶对水产品品质影响程度的方法,包括超声辅助冻结技术、高压处理技术、添加抗冻剂等,并对冻结技术的发展进行展望。结论为了更好地抑制冰晶形成带来的危害,在后续的研究中除了优化现有冻结技术和开发新型冻结技术外,还可以尝试将不同技术进行复合使用,谋求更佳的协同作用。此外,目前的新型冻结技术大多处于实验阶段,仍需对其作用机制进行深入探究,同时对不同技术的工艺参数进行优化。     

Technology-mining model concerning operation characteristics of technology and service providers

Owing to the high variety of industry development, technology and service providers (TSPs) are dedicated to the development of applied technologies. The operation purposes of these service providers are to provide customized services and technologies that meet the various client requirements and improve the capability of their clients via various projects. To outreach services to related enterprises successfully, the TSPs need an effective approach to explore the technology demands of enterprises. Based on the client demands, TSPs can establish effective operation strategies and technology development direction. Previously, the technology-development strategies are determined by domain experts or sales through trial and error. With regard to the operation requirements of the TSPs, this paper presents a technology-mining model based on their contract/project history. The aims of the proposed model focus on exploring technologies with higher client demands and significant research and development returns so that the TSPs can effectively expand and continue their business. Furthermore, the promotion sequence of different technologies can also be determined via the proposed-mining model. By application of the technology-mining model, effective suggestions can be provided to the TSPs for business extension.     

ITS Standards in the Context of Transportation and Telecommunication Infrastructure

Product standards have become increasingly important due toincreased technological complexity. A barrier to implementingintelligent transportation systems (ITS) technologies has beenthe development of compatible products and systems. Telecommunicationsinfrastructure has been considered one of the core elementsof ITS. Relevant communications options include wireline, wirelessand dedicated short-range communication systems. This paperpresents a case study on the emerging ITS industry, focusingon the communications aspect of the industry, and the complexityof the standardization process in the context of modern, interdependenttechnologies.     

AUTOMATED PROCESS PLANNING FOR PRINTED CIRCUIT CARD ASSEMBLY

Printed circuit card assemblies form the core of a vast array of contemporary manufactured products. The technologies for assembling printed circuit cards require a hierarchy of complex decisions for grouping card types and processes, staging components at assembly machines, arranging feeders, and sequencing placement operations. This paper is motivated by the largely unmet needs of industrial process planners for computer aids. Our objective is to develop a framework for the printed circuit card assembly process planning problem and to assess the current state of the research on appropriate models and solution methods. We first provide an overview of the essential elements of printed circuit card terminology, assembly technologies, and assembly system operations. Then we propose a decision hierarchy, survey the published literature, and identify needs for future research.     

A cyclic policy for the loading of multiple products on a vehicle with different compartment sizes

In this paper, we address a multi-product loading problem in which a vehicle (a truck or a ship) is used to transfer multiple products. The product demands are different but stationary over time. The vehicle consists of compartments of different sizes and each compartment can contain only one product type during each shipment. No shortages are permitted, and we assume that the inventory holding cost is significantly lower than the delivery cost. The objective is to minimize the setup rate, that is, the number of deliveries per time unit. A cyclic policy is shown to be optimal, and a heuristic algorithm is developed to determine the cycle length as well as the assignments of products to the compartments during each of the requisite number of shipments made during that cycle. A comparison of the solutions obtained by the proposed algorithm with the optimal solutions (or a bound) indicate that the algorithm provides solutions with optimal setup rates in most of the problem instances considered and, when not optimal, the setup rates of these solutions are close to optimal values.     

Discontinuities and Distributed Innovation: The Case of Biotechnology in Food Processing

This paper examines the organization of distributed innovation shaped by the major discontinuity in the life sciences and their associated technologies that has unfolded over the past three decades. While most studies have focused on its effects on pharmaceutical R&D, this paper studies food processing technologies, taking biotech exploitation of the ubiquitous micro-organism of Lactic Acid Bacteria as its example. Patents provide most of the data. Although highly distributed forms of innovation emerge from 1980 onwards, incumbents introduce virtually all innovations in this field, while the role of dedicated biotechnology firms (DBFs) remains negligible. Public research organizations contribute significantly to distributed R&D, and to a limited extent they also take on the role of economic actors. To explain the organizational characteristics of this distributed innovation this paper suggests a distinction between definition and solution of innovation problems. Extending Simon's analysis of complex problems, it is argued that definition and problem solving in innovation need not have the same levels of decomposability. By implication, the US model for biotech growth, emphasizing the market mechanisms of DBF formation, venture capital and scientist entrepreneurs, should not incautiously be pursued in all contexts and for all applications of biotechnology. Low decomposability of problem definition in innovations may preclude the emergence of these vehicles for market-driven growth, and in such cases distributed innovation must take other forms, including not least an active role of public science.