In this paper, a computer-implemented method for automating the transposition of a hospital’s nursing staff is proposed. The model is applied to the real case example ‘O’ hospital, which performs a transposition of its nursing staff once a year. Results are compared with real data obtained from this hospital’s current manual transposition system. The proposed method not only significantly reduces the time taken to construct the transposition, thereby significantly reducing management labor costs, but also is demonstrated to increase nurses’ levels of satisfaction with the process.

抄録全体を表示

We are interested in the print process on the manufacturing processes of auto parts supplier as an actual problem. The purpose of this research is to apply our scheduling technique developed in university to the actual print process in mass customization environment. Rationalization of the print process is depending on the lot sizing. The manufacturing lead time of the print process is long, and in the present method, production is done depending on worker’s experience and intuition. The construction of an efficient production system is urgent problem. Therefore, in this paper, in order to shorten the entire manufacturing lead time and to reduce the stock, we reexamine the usual method of the lot sizing rule based on heuristic technique, and we propose the improvement method which can plan a more efficient schedule.

抄録全体を表示

There usually exist large variations in assembly times at mixed-model assembly lines depending on difference of product-models. To increase efficiency of line handling under such circumstance, this paper concerns with a sequencing problem for the mixed-model assembly lines where each product is supposed to be assembled within the same cycle time. Then, we formulate a new type of the sequencing problem minimizing the weighted sum of the line stoppage times and the idle times, and propose a new sequencing method with the aid of Relief Man (RM). Since the resulting problem refers to a combinational optimization problem, we develop a hybrid method that applies meta-heuristics like SA (Simulated Annealing) together with TS (Tabu Search) in a hierarchical manner. Finally, we examine the effectiveness of the proposed method through computer simulations and show the advantage of using RM against various changes in production environment.

抄録全体を表示

The simplest method for making a production schedule is dispatch of jobs to idle machine tools. The method has a tendency of making a compact and efficient schedule, however the completion time of a job is not determined till the job is selected as the next job on an idle machine. Then, online scheduling methods have been developed, in which the production schedule is made as a job arrives at a machine. In this paper, an online scheduling method is developed for flexible flow shops under the due-date related criteria. A special feature of the method is to set the target completion time for each job and each stage. By numerical experiments, it is clarified that the method is better than FIFO (First In First Out) rule and especially the performance of the online scheduling is greatly superior to FIFO for the shops with heavy workload.

抄録全体を表示

Multi-shifts working condition is harder than the single shift one, and it is expected that the working condition be improved. One of approaches for the improvement is to make the work schedule so as to achieve the worker’s preference on it as large as possible. The preference depends on each of workers and it may vary with the time. Tackling with such a situation, an interactive multi-shift scheduling method is proposed in the paper. The method checks the feasibility of workers’ preferences, makes a fundamental shift schedule, and improves the schedule by shifts exchange between the workers. A necessary condition of a feasible schedule is clarified, and a prescreening procedure on the feasibility is developed. By the method, the workers’ preferences on shifts are reflected in the shift schedule as large as possible.

抄録全体を表示

The export oriented apparel manufacturers of developing countries produce apparel on the make-to-order basis instead of make-to-sell. As a result, there is no chance of stockout of goods that could be sold or overstock that has to be liquidated at deep discount at the end of the period. But an analogy can be drawn between stock of goods and capacity of production as idle capacity or shortage of capacity exists frequently while matching capacity with orders obtained. Considering capacity as a resource in inventory to be used in the future this paper applies newsboy problem to decide its use in production.

抄録全体を表示

The unprecedented challenges such as massive customizations and unstable demands require the manufacturing systems to be more flexible in responding marketplace changes and the system disturbances. In flexible manufacturing system, tool allocation strategy which involves tool planning in the system and scheduling of parts and tools can strongly affect the system efficiency. Considering the basic flows in FMS, a part-centric tool allocation strategy and a tool-centric tool allocation strategy are proposed. Generally, the part-centric allocation strategy involves few tool movements and the tool-centric allocation strategy involves few part movements. In this paper, the solution methods for the tool planning problem and the scheduling problem are proposed for both tool allocation strategies. Considering tool amount constraint, their performances are evaluated by simulations to compare their characteristics under different production conditions.

抄録全体を表示

This paper considers the multi-stage flexible flowshop scheduling problem to minimize the total completion time. We propose the hybrid branch and bound method with genetic algorithm for flexible flowshop scheduling problem, which provides the exact optimal solution. The genetic algorithm is used to derive an effective upper bound in the bounding scheme to realize the frequent update of current solution, which may cause the reduction of the number of nodes to be searched. The computational efficiency is improved compared with the conventional branch and bound method because of the reduction of the number of searched nodes in spite that the additional computational time for genetic operation.

抄録全体を表示

Delayed-feedback control is applied to stabilize the noise-induced chaotic behavior of a Duffing oscillator and a parametrically excited pendulum with noisy harmonic excitations. We first follow the standard pullback procedure of obtaining random invariant measure (RIM) and then intuitively construct Poincaré maps of RIM. Nonchaotic and chaotic sample processes are stabilized similarly to deterministic delayed-feedback control. The fractal structures of chaotic random processes are stabilized into point structures.

抄録全体を表示

In this paper, optimal control of a golf swing robot that is used to evaluate the performance of golf clubs is described. The robot has two joints, a rigid link and a flexible link that is a golf club. A mathematical model of the golf club is derived by Hamilton’s principle in consideration of bending and torsional stiffness and in consideration of eccentricity of the center of gravity of the club head on the shaft axis. A linear quadratic regulator (LQR) that considers the vibration of the club shaft is used to stop the robot during the follow-through. Since the robot moves fast and has strong non-linearity, an ordinary state observer for a linear system cannot accurately estimate the states of the system. A state observer that considers disturbances accurately estimates the state variables that cannot be measured. The results of numerical simulation are compared with experimental results obtained by using a swing robot.

抄録全体を表示

Modeling approach to obtain unified, hierarchical and legible model for multidisciplinary system is very important for performance prediction and analysis in complex system design. In this paper, graphic modeling methods, such as the use of block diagrams, bond graphs, functional models and object-oriented models, are reviewed firstly. Then, the modeling methods of bond graphs and functional models are compared, and a set of simplified fundamental items and a systematic modeling procedure to establish functional models are proposed. Finally, the proposed modeling method of functional models is applied to several examples of electrical, mechanical and hydraulic systems, and simulations performed on Simulink verify the practicability and effectiveness of the proposed modeling approach. The proposed modeling approach of functional models helps engineers to carry out modeling in an orderly way, so that the functional modeling method can be used by more engineers and applied in engineering analysis.

抄録全体を表示

The optimization of control gains for hydraulic servo systems is very difficult because of the high nonlinearities and uncertainties in the systems. In this paper, genetic algorithm is adopted to optimize the feedback gains for an over-centered variable displacement hydraulic motor (VDHM). The reciprocal of the ITAE criterion is proposed as the fitness function that evaluates the control performance. The appropriate specification of the genetic algorithms and the search range of each control gain for the speed control system are presented. It is found that the near-optimal values of the feedback gains can be obtained within 10 generations, which corresponds to about 100 experiments. The optimal gains are also obtained when the inertia or the supply pressure is varied. Optimized feedback gains are confirmed by plotting the fitness function in a given gain space and it was verified that the genetic algorithm is an efficient scheme in optimizing feedback gains for hydraulic servo systems.

抄録全体を表示

The frequency response function (FRF) obtained by Fourier transformation inevitably includes bias errors if data acquisition time is not long so that the signal decays fully. These errors are sensitive to the phase rather than the magnitude of FRF. And these errors will be amplified through transfer function synthesis (TFS) process since the operation of complex variables is used. In this paper, a method to remove these errors is proposed so as to enhance the results of TFS. Finally, numerical and experimental examples show that the FRF of synthesized structure can be predicted nearly exactly by the method proposed in this paper, even though the FRFs of substructures contain bias errors.

抄録全体を表示

A systematic approach of the energy method has been used for analyzing of deep drawing process. The so called simulated annealing algorithm has been used for energy optimization. In this method, the whole deforming region has been divided into five zones. Then the geometry has been expressed by sweeping the section curves defined on the boundary of each zone. The velocity fields have been expressed in a similar manner by sweeping the boundary velocity functions. In every step, the solution has been found through optimization of the total energy dissipation with respect to some parameters assumed in kinematically admissible velocity field defined over each zone. The energy dissipated in the bending zone has been estimated and added to the total energy due to strain and friction energies. In order to check the effectiveness of the present method, deep drawing of circular and square punches have been analyzed and variation of punch load versus punch depth, flange contour and distribution of thickness strain have been obtained and compared with published experimental data. The results show good agreement with the experiment.

抄録全体を表示

This paper describes the design of a non-overshooting proportional-integral-derivative (PID) controller with both pre-assigned initial integral state and a perturbation compensation scheme for motor positioning systems. According to the requirement of non-overshooting output response and the specified settling time in tracking a step reference signal, the PID gains and the initial integral state are determined systematically. The proposed PID control provides a continuous control signal when the nominal system is subject to sudden set-point changes, implying smooth system performance. To compensate for the system perturbation resulting from parameter variations and unknown load disturbances, an integral sliding perturbation observer is proposed and integrated into the PID-controlled system, which requires neither access to the time derivative of the state vector nor accurate knowledge of system parameters. A sliding mode is ensured throughout the entire response, and system perturbation is estimated by feeding a switching signal through an integrator. Due to the low-pass filtering characteristic of the integral action and the reduction of the required switching gain, the proposed scheme not only precisely compensates for system perturbation within the interested frequency range, but also effectively alleviates the chattering problem in control signals. The usefulness of the proposed design is demonstrated through an experimental study of a motor drive under load variations and disturbances.

抄録全体を表示