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Recent Advances in Multireference-Based Perturbation Theory
Nakano, Haruyuki,Hirao, Kimihiko Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.6
Accurate ab initio computational chemistry has evolved dramatically. In particular, the development of multireference-based approaches has opened up a completely new area, and has had a profound impact on the potential of theoretical chemistry. Multireference-based perturbation theory (MRPT) is an extension of the closed-shell single reference Møller-Plesset method, and has been successfully applied to many chemical and spectroscopic problems. MRPT has established itself as an efficient technique for treating nondynamical and dynamical correlations. Usually, a complete active space self-consistent field (CASSCF) wave function is chosen as a reference function of MRPT. However, CASSCF often generates too many configurations, and the size of the active space can outgrow the capacity of the present technology. Many attempts have been proposed to reduce the dimension of CASSCF and to widen the range of applications of MRPT. This review focuses on our recent development in MRPT.
Frequency Up-convert Energy Harvester for Automobiles
Mengda Liu,Rencheng Zheng,Kimihiko Nakano 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.춘계 No.-
In the last decade, vibration energy harvesting as a green energy source has received significant attention. Hence, this study concentrates on a piezoelectric-based low frequency vibration energy harvester using frequency up-conversion techniques for automobile applications. Magnetic force is used to induce impulses to excite the beam, and the related dynamic equations are derived. Owe to the attraction of the magnets, a two-stage vibration occurs during the experimental study, which can be acted as an enhancing method for low frequency vibration energy harvesting. Numerical simulations and experiments have been carried out to validate that the proposed system can up-convert frequency to harvest more power.
Chihiro Nakagawa,Yoshihiro Suda,Kimihiko Nakano,Shoichiro Takehara 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.4
Recently, the personal mobility vehicle (PMV), a vehicle suitable for personal use, has been developed. It moves at low speed and is sufficiently small that it can be ridden in pedestrian space. This vehicle is expected to be a new method of transportation that is practical and environmentally friendly. As one form of PMV, the authors propose a twowheel vehicle with two modes: a two-wheel steering and two-wheel driving bicycle mode and a parallel two-wheel mode. This vehicle has four electric motors, two for driving and two for steering, and one generator connected to the pedals. In the bicycle mode, the rider rotates the pedals to generate electric power, and the motors in the wheels produce torque using the generated energy. The front and rear wheels are steered by the electric motor according to the angle of the handle. Therefore, this bicycle is controlled by a steer-by-wire and a drive-by-wire system. In the parallel two-wheel mode, the vehicle is stabilized according to the theory of the inverted pendulum. In this paper, we focus on the bicycle mode and analyze its stability. Stabilizing the bicycle is not easy since the proposed vehicle has tires with small diameters and the traveling speed is assumed to be low. It is known that the stability of bicycles is tuned by adjusting the bicycle parameters and changing the rear steer angle. However, since we aim to use the vehicle in a narrow walking space at low speed, such conventional methods are not always suitable. The authors propose the stabilization of the bicycle using driving forces and design a controller using linear-quadratic control theory. The results of the numerical simulations show the proposed method is effective in stabilizing the bicycle.
이승용(Seung-Yong Lee),나카노키미히코(Kimihiko Nakano),김세광(Se-Kwang Kim) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.3
차량제어의 고도화에 의해, 자동 대열 주행 제어와 같은 정밀한 제어의 필요성이 더욱 높아지고 있다. 정밀 제어를 수행하기 위해서는 차량제어에 필요한 차량 파라미터를 항상 파악하는 것이 중요하다. 특히 화물 운송용 트럭의 경우, 화물 적재 상태에 따라 차량 질량과 차량 관성모멘트 등의 차량 파라미터가 크게 변화한다. 따라서 미지의 파라미터가 있을 경우, 실시간으로 파라미터 추정하여 제어시스템에의 반영이 요구된다. 본 연구에서는 차량이 곡선 주행할 때에 차량의 조향제어에 중요한 차량 파라미터 중 하나인 요관성모멘트에 대하여 Dual Kalman filter알고리즘과 GPS센서를 이용하여 차량이 주행 중에 미지의 요관성모멘트 값을 실시간으로 추정할 수 있는 방법을 제안하고, 차량동역학 상용 프로그램을 이용한 시뮬레이션을 통해 추정방법의 타당성을 검토한다. To achieve an advanced control of automobiles, it is necessary to acquire the values of the parameters of a vehicle in real time to conduct precise vehicle control practices such as automatic platooning control. Vehicle control is especially required in controlling trucks, as the mass and inertia change widely according to the loading conditions. Thereafter, we propose to estimate the yaw moment of inertia of the truck in real-time during travelling, by applying the dual Kalman filter algorithm, which estimates the state variables and values of the parameters simultaneously in realtime. The simulation results show that the proposed method is effective for the estimation, which uses commercial software for simulating and analyzing the vehicle dynamics.