作者机构：
[Tan, Yanliang; Lin, Fen; Hu, Tao; Yuan, Hongzhi; Mo, Yixiang; Fan, Zhongkai] Hengyang Normal Univ, Coll Phys & Elect Engn, Huangbai Rd 165, Hengyang 421008, Hunan, Peoples R China.;[Xie, Lin] Hengyang Normal Univ, Coll Math & Stat, Huangbai Rd 165, Hengyang 421008, Hunan, Peoples R China.
通讯机构：
[Yanliang Tan] C;College of Physics and Electronic Engineering , Hengyang Normal University, Huangbai Road 165#, Hengyang, Hunan Province 421008 , China
摘要：
As Rn-222 decays, an alpha particle is emitted and the residual polonium nucleus recoils in the opposite direction. At the end of the recoil path, 88% of the polonium atoms have a positive charge and 12% are neutral. The electric potential distribution in the 60 ml hemispherical internal cell of the radon monitor based on electrostatic collection is studied for reducing the combined probability of the positively charged Po-218 and the OH− produced by the ionization of water vapour in the air. The COMSOL software is used to simulate the electric potential distribution in the internal cell of the radon monitor based on the electrostatic collection method at 27°C, a pressure of 0.1 Mpa. For improving the collection efficiency of Po-218 ions, the average collection time along vertical and oblique lines is calculated when the upper surface of the internal cell is plastic, uncharged metal and charged metal, respectively. Assuming that the gas in the internal cell is uniformly distributed, the results show that if the upper surface of the hemispherical internal cell is plastic or uncharged metal, the electric potential formed in the internal cell is more uniform, and it is beneficial to reduce the total collection time of the positively charged Po-218 ions, thereby improving collection efficiency. The simulation results can be used as an effective reference for optimizing the design of the internal cell structure of the radon monitor based on electrostatic collection method.
摘要：
The control problem in ultrasound therapy is to destroy the tumor tissue while not harming the intervening healthy tissue with a desired temperature elevation. The objective of this research is to present a robust and feasible method to control the temperature distribution and the temperature elevation in treatment region within the prescribed time, which can improve the curative effect and decrease the treatment time for heating large tumor (>= 2.0 cm in diameter). An adaptive self-tuning-regulator (STR) controller has been introduced into this control method by adding a time factor with a recursive algorithm, and the speed of sound and absorption coefficient of the medium is considered as a function of temperature during heating. The presented control method is tested for a self-focused concave spherical transducer (0.5 MHz, 9 cm aperture, 8.0 cm focal length) through numerical simulations with three control temperatures of 43 degrees C, 50 degrees C and 55 degrees C. The results suggest that this control system has adaptive ability for variable parameters and has a rapid response to the temperature and acoustic power output in the prescribed time for the hyperthermia interest. There is no overshoot during temperature elevation and no oscillation after reaching the desired temperatures. It is found that the same results can be obtained for different frequencies and temperature elevations. This method can obtain an ellipsoid-shaped ablation region, which is meaningful for the treatment of large tumor. (C) 2012 Elsevier B.V. All rights reserved.
作者：
Jing-Fa Liu1,2* and Wen-Qi Huang1 1 School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China;2Department of Mathematics, Hengyang Normal College, Hengyang 421008, China.
期刊：
基因组蛋白质组与生物信息学报,2006年4(1):61-66 ISSN：1672-0229
通讯作者：
Liu, J.-F.
作者机构：
[Jing-Fa Liu1,2* and Wen-Qi Huang1 1 School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China] School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China. ljf720622@163.com
通讯机构：
School of Computer Science and Technology, Huazhong University of Science and Technology, China
摘要：
In this paper, we study an off-lattice protein AB model with two species of monomers, hydrophobic and hydrophilic, and present a heuristic quasi-physical algorithm. First, by elaborately simulating the movement of the smooth solids in the physical world, we find low-energy conformations for a given monomer chain. A subsequent off-trap strategy is then proposed to trigger a jump for a stuck situation in order to get out of the local minima. The algorithm has been tested in the three-dimensional AB model for all sequences with lengths of 13-55 monomers. In several cases, we renew the putative ground state energy values. The numerical results show that the proposed methods are very promising for finding the ground states of proteins.
