Journal of Advanced Simulation in Science and Engineering
Online ISSN : 2188-5303
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Papers
  • Masahisa Tabata, Shinya Uchiumi
    Volume 4 (2017) Issue 1 Pages 1-13
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    We show numerical results of triangular cavity flow problems solved by a Lagrange. Galerkin scheme free from numerical quadrature. The scheme has recently developed by us, where a locally linearized velocity and the backward Euler approximation are used in finding the position of fluid particle at the previous time step. Since the scheme can be implemented exactly as it is, the theoretical stability and convergence results are assured, while the conventional Lagrange-Galerkin schemes may encounter the instability caused by numerical quadrature errors. The scheme is employed to solve cavity flow problems in triangular domains, where we obtain two branches of stationary solutions.

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  • Junxiong Ni, Kun Zhao, Tohru Nakanishi, Koji Koyamada
    Volume 4 (2017) Issue 1 Pages 14-30
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    Currently, light emitting diodes (LED) have replaced cold cathode fluorescent lamps (CCFL) as backlighting systems in liquid crystal displays (LCD). However, the original single layer alone can only satisfy the needs of the panel display and cannot satisfy the requirements for a 3D display system or outdoor displays. In this paper, a new method is proposed to demonstrate that a high output can be achieved using spatial stacking of integrated LED light sources. Moreover, we also simulate the system and measure the light output and the distribution of the light. The system is efficient to provide high luminance while keeping a balanced light distribution. With this proposed high luminance spatial multiple-layer LED back-lighting system, many requirements, especially for the high light source, are supposed to be satisfied.

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  • Naoki Mita, Hideaki Uchida, Hideki Fujii, Shinobu Yoshimura
    Volume 4 (2017) Issue 1 Pages 31-43
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    The current approach to solving large-scale traffic problems is with the simulation of microscopic vehicle behaviors. However, few simulators are capable of conducting such simulations due to the high computational cost. In this study, we propose a new route search method using a simplified network to achieve speedup. We developed a practical implementation for a microscopic traffic simulator and applied the proposed method to a real road network in Okayama city under a dynamic routing condition. The results show that the proposed method reduces the number of links and nodes for route searches by 80% and the route search execution time by 98%.

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  • Junxiong Ni, Tie Shen, Yasuo Ebara, Koji Koyamada, Yoichi Kawakami, Yu ...
    Volume 4 (2017) Issue 1 Pages 44-63
    Released: March 31, 2018
    JOURNALS FREE ACCESS
    The Liquid Crystal Display (LCD) system has permeated every aspect of our daily lives. However, few people are aware of the blue light hazard of a Light Emitting Diode (LED), which is widely used as a light source in the backlight system of display devices. Presently, many manufacturers take a series of countermeasures, and most of them focus on reducing blue light through software technology, as this technique is easy to conduct and cost-friendly. However, there are still two manufacturers that insist on hardware methods to reduce the blue light hazard, as they seek to maintain the color performance.In this paper, we have proposed a new method of reducing blue light via hardware and have evaluated both the software method and the hardware method by means of numerical analysis. The new design is based on a backlight system in which the original white LED is modified so that the blue-band energy is reduced by 50% and cyan light LEDs are added among the white light LEDs. In addition, we have optimized and adjusted the distribution of the LEDs’ energy to reduce the harm of the blue light, and we have simultaneously maintained good color performance. According to the simulation results, the newly designed backlight unit could effectively cut down over 50% of the blue light and maintain the correlated color temperature (CCT) at 6081K, which approaches the standard value of 6500K. In addition, the color rendering index (CRI) can also be maintained at 74.818, which is almost the same as an ordinary white LED without blue light filtering.
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  • Yuki Hidaka, Hajime Igarashi
    Volume 4 (2017) Issue 1 Pages 64-77
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    This paper presents three-dimensional shape optimization of claw-pole motors. In the present method, the iron core of a claw-pole motor is subdivided into uniform voxel finite elements. The material attribute of each element, {1(core), 0(air)}, is determined from the shape parameters which vary in the optimization process. Thanks to this approach, time-consuming for mesh generation in the optimization process can be avoided. Moreover appropriately optimization algorithm is selected for reducing the computational costs. The core shape of a claw-pole motor is optimized so that the induced voltages at low and high speed conditions are maximized.

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  • Mikoto Yanai, Kazuki Abe, Tomonori Yamada, Hideki Fujii, Shinobu Yoshi ...
    Volume 4 (2017) Issue 1 Pages 78-98
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    The use of traffic simulators is getting increasingly popular for the assessment of policies to reduce traffic jams. However, simulators based on multi-agent models show some variability in results even if the input data and parameters are identical, because they use probabilistic phenomena, such as lane change of vehicles, which is determined by random numbers. Results of such simulations have been evaluated and analyzed by taking the mean of several trials, but such an approach fails to account for phenomena that have a low probability of occurring, but are still possible nonetheless, and therefore appropriate decisions may not be made. This paper verifies that possible phenomena can be taken into account by the cluster analysis combing a self-organizing map (SOM) and hierarchical clustering. This study clustered traffic volume data obtained from 600 traffic simulations near Okayama Station, grouped the traffic patterns, and analyzed the results.

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  • Shin-ichiro Sugimoto, Masao Ogino, Hiroshi Kanayama, Amane Takei
    Volume 4 (2017) Issue 1 Pages 99-116
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    This paper deals with three-dimensional non-steady eddy current analysis of a rotating machine as an example of a parallel finite element analysis including moving bodies. In general, high efficiency in parallel computing with a moving body is difficult to achieve. The hierarchical domain decomposition method (HDDM) is known as an efficient parallel finite element method. However, in cases that involve a moving body, the HDDM with static domain decomposition has not attained sufficient parallel efficiency. Moreover, the cost of dynamic domain decomposition is substantial. In this paper, we propose a new domain decomposition technique for the HDDM that enables us to achieve efficient scalability on massively parallel computers. Our method's parallel efficiency has been 93.3% on 96 computer nodes (1,536 cores) of the Oakleaf-FX supercomputer. Furthermore, an induction motor model with a seven million degrees of freedom mesh whose solution by conventional sequential computation requires more than a month has been successfully solved in approximately 1.60 hours using the proposed method.

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  • Atsushi Kamitani, Teruou Takayama, Ayumu Saitoh, Soichiro Ikuno
    Volume 4 (2017) Issue 1 Pages 117-131
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    A high-performance method is proposed for solving a linear system in the shielding current analysis of a cracked high-temperature superconducting film. After discretized with respect to time and space, the initial-boundary-value problem of the shielding current density reduces to a linear system at each iteration cycle of the Newton method. Although the linear system can be easily solved with GMRES, both crack length and the number of cracks affect convergence property significantly. In order to improve convergence property of GMRES, other variables than corrections of the current vector potential are all eliminated from the linear system. As a result, convergence property of GMRES is hardly influenced by either crack length or the number of cracks.

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  • Yukio Yasuhara, Naohisa Sakamoto, Yasuo Ebara, Hiroshi Katao, Koji Koy ...
    Volume 4 (2017) Issue 1 Pages 132-142
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    Effective data visualization techniques are required in order to support efficient earthquake analysis. So far, earthquake analysis experts have only been able to imagine 3D structures from typical 2D expressions. However, we consider that experts would be able to understand 3D structures more acculately and efficiently by providing them with an intuitive and interactive 3D display system. We focused on immersive projection technology (IPT) systems, more specifically on the CAVE system, to develop an effective support system for earthquake data analysis. We also developed an IPT oriented bimanual input based control interface for the support system to enable intuitive user interaction with the 3D display. In addition, we implemented a support tool for estimating fault planes in the earthquake phenomenon using the Spatio-Temporal Kriging method.

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  • Takeru Yanagida, Masami Iwase
    Volume 4 (2017) Issue 1 Pages 143-161
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    In this paper, motion control of a snake-like robot for winding and moving on smooth surface is developed. To design the motion control, a mathematical model of the snake-like robot is derived by Projection method. The Projection method leads both the mathematical model and constraints working in the mathematical model. The constraints give important information for winding and moving on the surface. State-Dependent Riccati Equation (SDRE) control strategy taking the constraints into account realizes winding and moving on the surface for the snake-like robot. The effectiveness of the proposed method is verified through numerical simulations.

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