We propose a penalty-based and constraint Bayesian optimization methods with an agent-based supply-chain (SC) simulator as a new Monte Carlo optimization approach for multi-echelon inventory management to improve key performance indicators such as inventory cost and sales opportunity loss. First, we formulate the multi-echelon inventory problem and introduce an agent-based SC simulator architecture for the optimization. Second, we define the optimization framework for the formulation. Finally, we discuss the evaluation of the effectiveness of the proposed methods by benchmarking it against the most commonly used genetic algorithm (GA) in simulation-based inventory optimization. Our results indicate that the constraint Bayesian optimization can minimize SC inventory cost with lower sales opportunity loss rates and converge to the optimal solution 22 times faster than GA in the best case.

Net-Oriented Analysis and Design (NOAD) is defined as three items: (1) Various nets are utilized as an effective modeling method. (2) Inter-relationships among verious nets are determined. (3) Verification or analysis methods for nets are provided and they are implemented based on the mathematical theory, that is Net theory. Very few methods have been presented to satisfy these three items. For example, the Real-Time SA method covers item (1) only. The Object-Oriented Analysis and Design method (OOA/OOD) covers items (1) and (2). NOAD can be regarded as an extension to OOA/OOD. This paper discusses how effectively various nets have been used in actual software development support metnods and tools and evaluates such several methods and tools from the NOAD viewpoint.

Investment planning for power plants involves making a long-term plan covering various facility investments, such as the construction of a new power plant or the replacement of an old plant with a new one, under uncertain environments. In this paper, we propose an optimization method for such a planning problem. Our method is based on decision tree analysis, in which uncertain environments are described as scenarios. The maintenance of existing plants is also taken into account by introducing the option of large-scale repair in addition to replacement. In order to avoid combinatorial explosion of failure event scenarios of plants, we introduce the concept of failure risk cost which contributes to simplification of the decision tree and reduction of the calculation time.

Both Petri nets and temporal logic have been widely used to specify concurrent programs. Petri nets appropriate to specify the behavioral structures of programs explicitly, while temporal logic is appropriate to specify the properties and constraints of programs. Since one can complement the other, using a combination of Petri nets and temporal logic is a highly promising approach to analyze, verify and synthesize concurrent programs. For the purpose of automatic program verification and synthesis, the emptiness problem (i.e., wheter a legal firing transition sequence satisfying a given temporal logic formula on a given Petri net exists) must be decidable. This paper reports a class to combine Petri nets and temporal logic as an infinite language and whose emptiness problem is decidable. We then show how to verify concurrent programs, using Petri nets and temporal logic, and also propose a compositional synthesis method that tune up reusable program components to satisfy a temporal logic specification.

Recently, technology roadmaps have been actively constructed by various organizations such as governments, industry segments, academic societies and companies [1]. While the common basic purpose of these roadmaps is sharing common recognition of the technology among stakeholders, there exists a specific role for each organization. One of the important roles of academic societies is to show the directions in which society is moving. The IEICE technical group on Concurrent System Technology (CST) established in 1993 stands at a turning point and needs to move forward in new directions after more than a decade of activities and contributions. However, neither top-down (market-pull/requirements-pull) nor bottom-up (technology-push) roadmapping is suitable for CST because CST is a kind of systems engineering. This paper proposes a new technology roadmapping methodology (middle-up-down technology roadmapping) for systems engineering and shows three future directions of CST and one roadmap for service systems that integrate CST and services science.

This paper concerns a Petri-net-based model for describing reactive and concurrent systems. Although many high-level Petri nets have been proposed, they are insufficiently practical to describe reactive and concurrent systems in the detail modeling, design and implementation phases. They are mainly intended to describe concurrent systems in the rough modeling phase and lack in several important features (e.g., concurrent tasks, task communication/synchronization, I/O interface, task scheduling) which the most actual implementations of reactive and concurrent systems have. Therefore it is impossible to simulate and analyze the systems accurately without explicitly modeling these features. On the other hand, programming languages based on Petri nets are deeply dependent on their execution environments and not sophisticated as modeling and specification languages. This paper proposes MENDEL net which is a high-level Petri net extended by incorporating concurrent tasks, task communication/synchronization, I/O interface, and task scheduling in a sophisticated manner. MENDEL nets are a wide-spectrum modeling language, that is, they are suitable for not only modeling but also designing and implementing reactive and concurrent systems.

This paper proposed a practical method of program validation for state-based reactive concurrent systems. The proposed method is of particular relevance to plant control systems. Plant control systems can be represented by extended state transition systems (e.g., communicating asynchronous transition systems). Our validation method is based on state space analysis. Since naive state space analysis causes the state explosion problem, techniques to ease state explosion are necessary. One of the most promising techniques is the partial order method. However, these techniques usually require some structural assumptions and they are not always effective for actual control systems. Therefore, we claim integration and harmonization of verification (i.e., state space analysis based on the partial order method) and simulation (i.e., conventional validation technique). In the proposed method, verification is modeled as exhaustive simulation over the state space, and two types of simulation management techniques are introduced. One is logical selection (pruning) based on the partial order method. The other is heuristic selection based on priority (a priori precedence) specified by the user. In order to harmonize verification (logical selection) and conventional simulation (heuristic selection), we propose a new logical selection mechanism (the default priority method). The default priority method which prunes redundant state generation based on default priority is in harmony with heuristic selection based on the user's priority. We have implemented a practical validation tool, Simulation And Verification Environment for Reactive Concurrent Systems (SAVE/RCS), and applied it to chemical plant control systems.

A Discrete Event System (DES) is a system that is modeled by a finite automaton. A Cooperating Discrete Event System (CDES) is a distributed system which consists of several local DESs which are synchronized with each other to accomplish its own goal. This paper describes the automatic synthesis of a CDES from a modular temporal logic specification. First, MPTS (Modular Practical Temporal Specification language) is proposed in which the new features (modular structure and domain specification) are appended to temporal logic. To overcome the "state explosion problem", which occurs in generating a global automaton in former synthesis methods using temporal logic, a compositional synthesis is proposed where automata are reduced at every composition step.

Hypersequential programming is a new method of concurrent-program development in which the original concurrent program is first serialized, then tested and debugged as a set of sequential programs (scenarios), and finally restored into the target concurrent program by parallelization. Both high productivity and reliability are achieved by hypersequential programming because testing and debugging are done for the serialized versions and the correctness of the serialized programs is preserved during the subsequent parallelization. This paper proposes scenario-based hypersequential programming for reactive multitasking systems that have not only concurrency and nondeterminacy, but also interruption and priority. Petri nets with priority are used to model reactive systems featuring interruption and priority-based scheduling. How reactive systems are made highly reliable by this approach is explained and the effectiveness of the approach is demonstrated through the example of a telephone terminal control program.

This paper describes MENDELS ZONE, a Petri-net-based concurrent programming environment, which is especially suitable for cooperating discrete event systems. MENDELS ZONE adopts MENDEL net, which is a type of high level (hierarchical colored) Petri net. One of the characteristics of the MENDEL nets is a process-oriented hierarchy like CCS, which is different from the subnet-oriented hierarchy in the Jensen's hierarchical colored Petri net. In a process-oriented hierarchy, a hierarchical unit is a process, which is more natural for cooperating and decentralized discrete event control systems. This paper also proposes a design methodology for MENDEL nets. Although many Petri net tools have been proposed, most tools support only drawing, simulation, and analysis of Petri nets; few tools support the design methodology for Petri nets. While Petri nets are good final design documents easy to understand, analyzable, and executable it is often difficult to write Petri nets directly in an earlier design phase when the system structure is obscure. A proposed design methodology makes a designer to construct MENDEL nets systematically using causality matrices and temporal logic. Furthemore, constructed MENDEL nets can be automatically compiled into a concurrent programming language and executed on a parallel computer.