Formation enthalpies of ruthenium fluorides: Ruthenium-fluoridizer agent systems

Published in the literature data on Ru-TbF₄ (a scheme of changes of its components in the condensed phase is proposed here) and Ru-IF₅-Ag gas phase systems have been critically reviewed. The formation enthalpies (298 K, kJ/mol) of gaseous Ru₃F₁₅ -2600.5 ± 1.7, Ru₂F₁₀ −1686.2 ± 1.8, RuF₅ −740.5 ± 9.8, RuF₆ −848.3 ± 10, RuF₄ −646 ± 10, RuF₃ −390.3, RuF₂ −130.3 ± 10.3, RuF 271.2 and crystalline RuF₄–854.3 ± 1.1, RuF₃(c) −672.8, and Pt₃F₁₅(c) −2142.6 ± 12 are calculated. The applicability of the proposed set of thermodynamic characteristics to describe the thermal and chemical behavior of ruthenium fluorides has been shown.     

Modelling for agile manufacturing systems

To address the challenges of a rapidly changing manufacturing market, a new type of manufacturing system with characteristics of reconfigurability, reusability and scalability, an agile manufacturing system (AMS) has to be developed. Reconfigurability is an essential feature of AMS. Such a system can use basic building blocks, both hardware and software, which can be reconfigured quickly and reliably. A fundamental early step in the reconfiguring process for an agile manufacturing system is to develop a model that adequately describes the proposed system, in order to be able to study and evaluate the impact of the reconfiguring decision on the system performance, before its construction. Therefore, the rapid modelling and reusable modelling capabilities are demanded. In this paper, an Object & Knowledge-based Interval Timed Petri-Net (OKITPN) approach is proposed, which provides an object-oriented and modular method of modelling manufacturing activities. It includes knowledge, interval time, modular and communication attributes. The features of object-oriented modelling allow the AMS to be modelled with the properties of classes and objects, and make the concept of software IC possible for rapid modelling of complex AMSs. Once all of the Interval Timed Petri-Net (ITPN) objects are well defined the developers need to consider only the interfaces and operations relating to the ITPN objects. In order to demonstrate the capability of the proposed OKITPN, it has been used to model rapidly AMSs that are reconfigured according to requirements.     

An integrative model of autonomous agent teammate-likeness

ABSTRACT

Advancements in autonomy are beginning to allow humans to partner with machines in order to accomplish work tasks in various settings. As human–agent teaming (HAT) becomes more prevalent as a research topic, the need to understand humans’ psychological perceptions of the machine partner is increasingly important, especially in terms of its perceived role, which may ultimately impact trust and team effectiveness. Specifically, it remains unclear how humans perceive intelligent agents and how consistent these perceptions are with existing taxonomies found in the psychology of teams. The present paper presents a definition of the construct of autonomous agent teammate-likeness (AAT) and a conceptual model of its components, reviews related concepts and germane research and proffers a number of propositions to guide future research. The goal is to contribute to the nascent literature on HAT by establishing a theoretical foundation for the AAT construct, upon which researchers can advance research on HAT.     

Scheduling manufacturing systems for delayed product differentiation in agile manufacturing

Production of customized products to respond to changing markets in a short time and at a low cost for agile manufacturing can be implemented with delayed product differentiation in a manufacturing system. The successful implementation of delayed product differentiation lies in efficient scheduling of the manufacturing system. Scheduling problems in implementing delayed product differentiation in a general flexible manufacturing system are defined, formulated and solved here. The manufacturing system consists of two stages: machining and assembly. At the machining stage, a single machine is used to produce standard component parts for assembly products. These parts are then assembled at the assembly stage by multiple identical assembly stations to form customized products. The products to be produced in the system are characterized by their assembly sequences represented by digraphs. The scheduling problem is to determine the sequence of products to be produced in the system so that the maximum completion time (makespan) is minimized for any given number of assembly stations at the assembly stage. Based on the representation of assembly sequence of the products, three production modes are defined: production of a single product with a simple assembly sequence ; production of a single product with a complex assembly sequence ; and production of N products . According to the three defined production modes, the associated scheduling problems are defined as G s scheduling problems, G c scheduling problems and N-product scheduling problems, respectively. Optimal and heuristic methods for solving the scheduling problems are developed. The computational experiment shows that the heuristics provide good solutions to the scheduling problems.     

Optimization analysis for recycle-oriented manufacturing systems

Recycling has been recently recognized as one of effective tools for solving environmental problems. In this respect present and future manufacturing systems should take the recycling of materials used into consideration. This paper points out the issues contained in such a recycle-oriented manufacturing system, then the basic parts-flow in the product's life cycle is clarified by taking account of re-use and re-production of the parts contained in the product. A model is constructed to maximize two measures of performance—total profit and recycling rate. This is solved by goal programming. Finally, a numerical example is used to demonstrate the effectiveness of the model proposed.     

A participatory systems design methodology for changeable manufacturing systems

The ability to adapt to changes in products, processes and technologies is a key competitive factor. Changeable manufacturing paradigms have emerged to address this need, but the industrial implementation remains challenging. In this paper, a participatory design methodology for changeable manufacturing systems is proposed, including requirements specification, selection of appropriate manufacturing paradigm and suitable physical and logical enablers. The methodology supports companies in determining the potential for and mechanisms of transitioning towards changeable manufacturing systems, based on knowledge of products, production, technologies and facilities. The developed methodology is applicable to both new and existing manufacturing systems. It is demonstrated in two industrial cases which highlight its applicability and differences in the appropriate recommended manufacturing systems transition towards changeability as a result of differences in manufacturing characteristics, change requirements and enablers.     

A distributed scheduling method for computer integrated manufacturing: the use of local area networks in cellular systems

This paper describes a distributed scheduling approach that takes into account characteristics of the communication network in the computer-integrated manufacturing environment. The approach is based on a network-wide bidding scheme wherein the scheduling decision is made by collecting the price of each manufacturing cell for taking on the job; different dynamic scheduling heuristics can be incorporated in this scheme and executed in a distributed fashion. This paper also describes the formalism and model for the distributed scheme that can be embedded in a communication protocol. A simulation study has been conducted to evaluate and compare the performance of different strategies or heuristics employed in the scheduling method.     

Autonomy and viability-measures for agent-based manufacturing systems

An Agent-Based Manufacturing System (ABMS), represented as a model of future manufacturing systems, is introduced in this article. In an ABMS, computerized agents are autonomous and working collaboratively through the regulation of structured dialogues. The autonomy functions of an agent are demonstrated by four internal functions: internal resource management, a reflexivity mechanism, a goal adjustment mechanism, and collaboration management. The four functions assist an agent in interacting with other agents and with the environment and to adjust itself to the situation in the dynamic environment. Agents are similar to living systems. Based on the concept of living systems, autonomy and viability at the agent level are proposed and defined as new measures for manufacturing systems. A theory of coexistence and parasitism of ABMS is developed to identify the coexistent and parasitic characteristics of ABMS. Applications of the theory to real cases are also illustrated. Finally, a road map for the future research of distributed, collaborative manufacturing organizations is shown, based on the ABMS model developed.     

Data-driven generic simulators for flexible manufacturing systems

Despite the apparent move toward using data-driven simulators in manufacturing modelling, as opposed to simulation languages and packages that require programming, there have been few rational efforts to evaluate the development and use of these tools. As the number of tools continues to grow, such evaluation is necessary if simulation users are going to make sensible informed choices. This paper presents two specialized data-driven simulators developed to model Flexible Manufacturing Systems called RENSAM (Rensselaer Simulator for Automated Manufacturing) and RENVIS (Rensselaer Visual Interactive Simulator). Experience with these packages leads to consideration of the benefits of using such tools. Advantages include the ease with which models can be developed and the rapid pace of that development, and the enforcement of proper statistics collection; disadvantages include misplaced perception of how easy the tool is to use, weaknesses in implementation and the limitations of the simulator. It is shown that where a tool is deployed in the modelling process is of paramount importance, and guidance on deployment is provided. Other guidelines for developers and users of data-driven simulators are also developed.     

Conceptualizing tools for autonomous vehicle storage and retrieval systems

Autonomous vehicle storage and retrieval systems utilize rail-guided vehicles moving in rectilinear paths within and between the aisles of unit load storage racks. Vertical vehicle movement is provided by lifts installed at fixed locations along the rack periphery. As an alternative to traditional automated storage and retrieval systems, autonomous vehicle systems enable users to match vehicle fleet size and the number of lifts to the level of transactions demand in a storage system. Analytical conceptualizing tools based on the features of autonomous vehicle systems are proposed for modelling expected performance as a function of key system attributes including storage capacity, rack configuration and fleet size. The models are demonstrated for a sample problem and compared with analytical conceptualizing tools used for automated storage and retrieval systems.     

Integrated analytical models for flexible manufacturing systems

Product form queueing networks (pfqn) and generalized stochastic Petri nets (gspn) have emerged as the principal performance modelling tools for flexible manufacturing systems (fms). In this paper, we present integratedpfqn-gspn models, which combine the computational efficiency ofpfqn and representational power ofgspn by employing the principle of flow-equivalence. We show thatfms that include nonproduct form characteristics such as dynamic routing and synchronization can be evaluated efficiently and accurately using the integrated models.     

可生存系统的自主可识别性机制研究

提出了一种可生存系统的自主可识别性机制。按此机制，可识别性通过定义面向生存性的可识别性参数实现，自主性通过自主识别单元控制进程实现。首先，定义了若干可识别性参数，依据可识别参数的累计分布函数确定了动态可变的阈值约束；然后，基于可识别参数的参考基点，给出了服务连接可识别性检测的计算方法，并通过自主识别单元来控制实现服务连接的断开和系统资源的释放；最后，在Emulab环境下使用实时的ClarkNet WWW服务器的访问数据进行了仿真性能实验，结果显示上述方法可以有效地识别出非法连接并且重新分配系统资源给合法用户，提高了系统可生存性的自主认知能力和服务承载能力。     

A novel ultrasonic sensing system for autonomous mobile systems

This paper presents a novel ultrasonic sensing system for autonomous mobile systems. We describe how wide-angled ultrasonic transducers can be used to obtain substantial information from the environment. This can be achieved by exploiting the overlapping of detection cones from neighbor sensors and by receiving cross echoes between them. The ultrasonic sensing system also allows the detection of multiple echoes from different echo paths for each sensor. In this way, a significantly higher number of echoes can be obtained in comparison to conventional ultrasonic sensing systems for mobile robots. In order to benefit from the increased sensor information, algorithms for adequate data post-processing are required. In this context, we describe how an environment model can be created from ultrasonic sensor data.     

Exploring self-organization and self-adaption for smart manufacturing complex networks

Trends toward the globalization of the manufacturing industry and the increasing demands for small-batch, short-cycle, and highly customized products result in complexities and fluctuations in both external and internal manufacturing environments, which poses great challenges to manufacturing enterprises. Fortunately, recent advances in the Industrial Internet of Things (IIoT) and the widespread use of embedded processors and sensors in factories enable collecting real-time manufacturing status data and building cyber–physical systems for smart, flexible, and resilient manufacturing systems. In this context, this paper investigates the mechanisms and methodology of self-organization and self-adaption to tackle exceptions and disturbances in discrete manufacturing processes. Specifically, a general model of smart manufacturing complex networks is constructed using scale-free networks to interconnect heterogeneous manufacturing resources represented by network vertices at multiple levels. Moreover, the capabilities of physical manufacturing resources are encapsulated into virtual manufacturing services using cloud technology, which can be added to or removed from the networks in a plug-and-play manner. Materials, information, and financial assets are passed through interactive links across the networks. Subsequently, analytical target cascading is used to formulate the processes of self-organizing optimal configuration and self-adaptive collaborative control for multilevel key manufacturing resources while particle swarm optimization is used to solve local problems on network vertices. Consequently, an industrial case based on a Chinese engine factory demonstrates the feasibility and efficiency of the proposed model and method in handling typical exceptions. The simulation results show that the proposed mechanism and method outperform the event-triggered rescheduling method, reducing manufacturing cost, manufacturing time, waiting time, and energy consumption, with reasonable computational time. This work potentially enables managers and practitioners to implement active perception, active response, self-organization, and self-adaption solutions in discrete manufacturing enterprises.     

Synthesis of control implementation for discrete manufacturing systems

The paper presents the concepts and steps required to synthesize a correct control implementation for discrete manufacturing systems, starting from Grafcet specifications. A formal framework implementing the synthesis steps is also presented and illustrated with an example of a drilling system.     

一类线性自治型切换系统的镇定设计

利用相平面方法研究了一类二阶线性自治切换系统的渐近镇定问题。针对每个子系统的平衡点为不稳定的焦点类型,设计了时不变系统的“最镇定”控制,并给出了保证闭环系统渐近镇定的充分和必要条件。通过数值仿真验证了这种设计方法的有效性。本方法也适用于子系统平衡点为基他类型的二阶切换系统。     

Configuring cellular manufacturing systems

We present a three-stage procedure for configuring machines into manufacturing cells, and assigning the cells to process specific sets of jobs. First, operations are assigned, with the objective of minimizing the deviation between available capacity and the workload assigned to each machine. We then extended King's algorithm to group machines based on similarities of operations. Finally a direct-search algorithm for defining the composition of manufacturing ceils is offered. A comprehensive example is also included.     

Interoperable manufacturing knowledge systems

For many years now, the importance of semantic technologies, that provide a formal, logic-based route to sharing meaning, has been recognised as offering the potential to support interoperability across multiple-related applications and hence, drive manufacturing competitiveness in the digital manufacturing age. However, progress in support of manufacturing enterprise interoperability has tended to be limited to fairly narrow domains of applicability. This paper presents a progression of research and understanding, culminating in the work undertaken in the recent EU FLEXINET project, to develop a comprehensive manufacturing reference ontology that can (a) support the clarification of understanding across domains, (b) support the ability to flexibly share information across interacting software systems and (c) provide the ability to readily configure company knowledge bases to support interoperable manufacturing systems.     

Family based dispatching in manufacturing networks

Intrinsic to family based dispatching is the grouping of similar types of jobs in front of a machine for joint processing. Machine flow times may be improved in this way, as less time is spent on set-ups. Our observations in practice, however, suggest that family based dispatching may result in a bulky arrival pattern for successor manufacturing stages, thereby causing additional delay. So far, literature seems to neglect this effect. To explore this issue we develop queuing theoretical approximations of flow times for a simple two-stage shop. It appears that the optimal batch size for the shop is typically smaller than the optimal batch size for the batch machine. Furthermore, we propose extensions to existing dispatching rules by using information on successor stages. Existing and new extended rules are tested by an extensive simulation study. In line with the queuing theoretical analysis the outcomes indicate that exhaustive rules – assuming batch size to be equal to family queue length – are clearly outperformed by non-exhaustive rules – allowing for smaller batches. Moreover, results show that the inclusion of local information on successor stages in rule decision making improves shop flow times.     

Coordinating batching decisions in manufacturing networks

Family-based dispatching heuristics aim for improving job flow times by reducing time spent on set-ups. They realise set-up efficiencies by batching similar types of jobs. By their intuitiveness and the simplicity of their decision logic, they may contribute to an easy to implement and viable strategy in many practical settings. Similar to common dispatching rules most existing family-based dispatching heuristics are myopic, i.e. their decision scope is restricted to a single manufacturing stage. Hence, they neglect opportunities for improving shop performance by coordinating batching decisions with other manufacturing stages. Case examples from industry underpin the need for exploring these opportunities. We do so by studying a simple two-stage flow shop, entailing a serial and a batch stage. To facilitate shop coordination we propose extensions to existing family-based dispatching heuristics. Extended heuristics seek to further increase set-up efficiencies by allowing for upstream job re-sequencing, and pro-active set-ups, i.e. set-ups that may be initiated prior to the arrival of a job. Outcomes of an extensive simulation study indicate significant performance gains for extended heuristics vs. existing heuristics. Performance gains are largest for moderate and high set-up to run-time ratios.