Shinsuke Akagi

Influence of Fuel Cost on the Operation of a Gas Turbine-Waste Heat Boiler Cogeneration Plant

The influence of fuel cost on the operation is investigated for a gas turbine-waste heat boiler cogeneration plant by an optimal operational planning method. A planning method is first presented by which the operational policy of each piece of constituent equipment is determined so as to minimize the operational cost. Then, a case study is performed for a cogeneration plant used for district heating and cooling. Through the study, it is made clear how the optimal operational policy and the economic or energy conservative properties are influenced by the costs of purchased electric power and natural gas. It is also shown that the optimal operational policy is superior in economy as compared with other conventional ones.

Agent-Based Distributed Design System Architecture for Basic Ship Design:

This paper proposes an agent-based distributed design system architecture for complicated, large engineering systems and de velops an experimental implementation of the architecture for basic ship design. First, dependency and concurrency in design activities of an engineering system are discussed from the viewpoints of hierarchical system structure and entity-and-attribute relationship. It reveals the possibilities of parallel execution of design operations from a systematic viewpoint. Second, the design operations are classified into gener ating system structures, configuring spatial arrangement, determining system attributes and selecting system components. In the architec ture, design operations for attributes that are major parts are modeled with object orientation, and they are distributed to agents by extend ing an object-oriented programming technique to an agent approach. The others are encapsulated as independent task agents. After describing key concepts for its computer implementation, this paper shows an application for basic ship design.

Hybrid Approach to Plant Layout Design Using Constraint-Directed Search and an Optimization Technique

A hybrid type approach to plant layout design is presented using a constraint-directed search procedure and a mathematical optimization technique. In layout design, a plant must be arranged to satisfy spatial constraints imposed by its components. In our approach the whole space of a plant building is divided into the finite compartments with a modular size in order to separate the description of the layout into the combinatorial part and the sizing part. The approach consists of two steps. In the first step, a constraint-directed search procedure is applied to find a combinatorial solution among plant components so as to satisfy the spatial layout conditions. In the second step, an optimization technique is applied to determine the actual dimensions of components so as to minimize a measure of an overall size of a plant building considering size of components. The approach is implemented with an object-oriented programming environment and the system can automatically produce a layout from the declarative representation of layout conditions. Finally, the approach has been applied to the design of a nuclear power plant in order to check its validity and effectiveness.

DESIGN OPTIMIZATION OF MULTI-LINK SUSPENSION SYSTEM FOR TOTAL VEHICLE HANDLING AND STABILITY

This paper discusses the design problem of vehicles using multi-link suspension system with the aim of totally optimizing vehicle handling and stability. Since this problem includes many evaluation items, and multi-link suspension system has interconnected behavior, the optimization is so complicated. An efficient and computable model is indispensable for compromising the total optimization. This paper investigates a hierarchical structure of objectives, introduces appropriate simulation models for respective items, and formulates a mathematical optimization model based on them. Further, we apply a genetic algorithm based optimization method to this problem. The genetic algorithm is based on Simple GA and introduces several extensions such as fitness function for constrained multi-objective optimization problems, similarity-based selection, direct crossover within side constraints, etc. The result of optimization calculation shows the validity of the optimization model and the optimization algorithm as mathematical computation based design methods.

Building an expert system for the preliminary design of ships

An expert system for the preliminary design of ships developed. The design process is understood as determining design variables and the relationships among design parameters. The relationships among the elements of design knowledge are represented by a network model. The object-oriented knowledge representations are introduced in the computer system to manipulate design variables such as the principle particulars of a ship in the network model. The expert system based on the above concept provides the following functions: (1) flexibility for building a model and easy modification of the model; (2) effective diagnosis of the design process by using rule-based knowledge representations; (3) hybrid function with both symbolic treatment of the design knowledge and numerical computations by coupling the systems programmed in LISP and FORTRAN and (4) a supporting method for determination of the design variables. Finally the systems validity and effectiveness is ascertained by applying it to the preliminary design of a bulk carrier ship.

Optimal Operational Planning of a Gas Turbine Combined Heat and Power Plant Based on the Mixed-Integer Programming

Abstract A planning method is proposed for determining the optimal operational policy of a gas turbine combined heat and power plant connected with distributed heat supply plants at several districts. For the purpose of the efficient planning, a hierarchical approach is adopted. At the first level, the optimal operational policy is determined for each heat supply plant so as to minimize the required amount of input energy. At the second level, the optimal operational policy is determined for the combined heat and power plant so as to minimize its operational cost. These optimization problems are formulated respectively as a mixed-integer quadratic programming problem and a mixed-integer linear one, and they are both solved by applying the branch and bound method. Lastly, the effectiveness of the proposed method is ascertained through a case study.

Total Design Optimization of Multi-Link Suspension System for Vehicle Handling and Stability.

This paper discusses the design problem of vehicles using multi-link suspension system with the aim of totally optimizing vehicle handling and stability. Since this problem includes many evaluation items, and multi-link suspension system has interconnected behavior, the optimization is so complicated. An efficient and computable model is indispensable for compromising the total optimization. This paper investigates a hierarchical structure of objectives, introduces appropriate simulation models for respective items, and formulates a mathematical optimization model based on them. Further, we apply a genetic algorithm based optimization method to this problem. The genetic algorithm is based on Simple GA and introduces several extensions such as fitness function for constrained multi-objective optimization problem, similarity-based selection, direct crossover within side constraints, etc. The result of optimization calculation shows the validity of the optimization model and the optimization algorithm as a mathematical computation based design methodology.

Multi-Objective Optimal Design of Vehicle Power Train : Optimization of Torque Converter Geometry

Multi-objective optimal design of a vehicle power train is presented for the geometry of a torque converter. The power train is composed of an engine, a torque converter, a transmission and a final gear, and it is an essential subsystem of a vehicle in items of its acceleration performance and fuel economy, etc. In this paper, a practical method of optimizing the geometry of a torque converter is proposed, and trade-off relationships among the objectives are demonstrated by means of design optimization. In the optimization calculation the geometry is manipulated using spline curves, an appropriate evaluation method for torque converter performance is utilized, and successive quadratic programming is used as an optimization algorithm. A computational example demonstrates the effectiveness of the proposed optimization method.

OPTIMAL OPERATIONAL PLANNING OF A GAS TURBINE COMBINED HEAT AND POWER PLANT BASED ON THE MIXED-INTEGER PROGRAMMING

A planning method is proposed for determining the optimal operational policy of a gas turbine combined heat and power plant connected with distributed heat supply plants at several districts. For the purpose of the efficient planning, a hierarchical approach is adopted. At the first level, the optimal operational policy is determined for each heat supply plant so as to minimize the required amount of input energy. At the second level, the optimal operational policy is determined for the combined heat and power plant so as to minimize its operational cost. These optimization problems are formulated respectively as a mixed-integer quadratic programming problem and a mixed-integer linear one, and they are both solved by applying the branch and bound method. Lastly, the effectiveness of the proposed method is ascertained through a case study.

Optimal design of a linkage mechanism used for fork lift (Application of a nonlinear optimization method of minimax type)

フォーク・リフト用リンク機構の形状を合理的に決定するための一最適設計手法を提案した.フォークの上下運動に伴う各種静力学的制約条件の下に,原動節の最大駆動トルクを最小にするリンク形状を決定する問題を,一つのミニマックス型非線形最適化問題として定式化した.一般縮小勾配法に基づいて最適解を求め,上記最大駆動トルクの大幅な低減化等が可能なことを示し,本手法の有効性を検証した.