Numerical modeling and simulation of temperature distribution uncertainty subject to ferromagnetic thermoseeds hyperthermia

In the process of ferromagnetic thermoseeds mediated magnetic induction hyperthermia, the tempera- ture distribution in the tumor region is a key factor to determine the therapy effect. During the preoperative treatment planning, discrepancies of the treatment parameters may lead to the temperature distribution uncertainty within the target area. Inaccurate prediction of temperature distribution may induce the treatment failure; therefore, it would be significant to investigate the uncertainty of tissue temperature prediction caused by the disturbance of calculation parameters. In this paper, 3D temperature field and necrosis zone of tissues in ferromagnetic thermoseeds hyperthermia are simulated by the finite volume algorithm, and effects of parameter uncertainties on the temperature distribution are revealed. Results show that selecting appropriate magnetic field parameters for treatment is a priority to guarantee therapeutic effect. Thermoseed properties and blood perfusion rate are the obvious disturbing terms for temperature distribution, while the metabolic heat of bio-tissues can often be ignored within limits. Our investigation is of importance for guiding reasonable and optimal preoperative treatment planning.     

线性离散时滞系统的鲁棒稳定性分析

依据稳定性理论和矩阵范数理论推导了线性离散时滞系统鲁棒稳定的充分条件,在此基础上得到了不确定时滞离散系统扰动矩阵的范数界,根据不确定离散系统的鲁棒D-稳定的定义,给出了确保不确定离散时滞系统所有极点均位于给定圆形区域系统扰动矩阵的范数界,这些条件形式简单,易于实现,是用于初步检验系统稳定性的有用工具.     

广东江门古兜山保护区光叶红豆种群径级结构与空间分布格局

为了解广东江门古兜山省级自然保护区内天然分布的珍稀濒危植物光叶红豆Ormosia glaberrima 种群的生存现状，本研究基于1 hm²固定样地数据进行光叶红豆种群径级结构分析，并采用点格局分析方法研究种群空间分布格局。结果表明，光叶红豆的径级结构呈倒“J”型，个体以幼树为主，同时幼树和壮龄树死亡率也较高，随着径级增大，个体的存活率趋于稳定，整体表现为增长型，种群结构较为稳定；在小空间尺度上，光叶红豆个体间呈聚集分布，而随着空间尺度的增大，个体倾向于随机分布。光叶红豆幼树呈聚集分布，随着径级增加，空间分布的聚集程度下降，成树呈随机分布。因此，古兜山光叶红豆种群的空间分布格局主要受幼树、壮龄树死亡率较高和密度影响，建议通过适度开辟林窗等方式加强就地保护，结合迁地保护降低幼树密度，促进光叶红豆种群更新。     

企业家定价的博弈分析

企业家劳动的过程是企业家素质的“创造性破坏”的过程，企业家素质创造了企业家利润。在投资者与企业家之间对企业家利润进行一次博弈和多次博弈，通过多次分配博弈，使得企业家定价更趋合理。     

y+值对翼型气动参数计算精度的影响研究

基于RAE 2822翼型,为了研究粘性底层无量纲参数y+对翼型气动参数计算精度的影响,采用ANSYS ICEM剖分的计算域网格和三维N-S控制方程的有限体积法离散格式,选取SST湍流模型,在不同的y+值下借助ANSYS CFX模块数值计算了该翼型的气动参数,分析了相对误差,绘制了压力系数分布云图。结果表明:过大的y+值导致误差增大;在y+的理论值11.63附近,计算精度变化较小;较小的y+可使精度进一步提高,但过小的y+并不能得到过高的计算精度。y+值对翼型边界不同区域的计算精度影响有所不同,翼型气动参数数值计算时推荐y+取2-4。     

Characterization of Titanium-Containing Compounds in Gray Iron

Titanium produces different compounds in gray iron. In order to determine their characteristics, a scanning electron microscope, an energy dispersive X-ray spectroscopy, and an optical microscopy were used to analyze the morphology, distribution, and composition of titanium-containing compounds in metal- Iographic specimens and machined surfaces in four gray irons. The results show that the titanium-containing compounds in the gray irons are complex compounds containing V, Nb, Mn, S, and other metals, depending on the concentration of these elements in the iron. The number of titanium-containing compounds increases with increasing Ti content in the gray iron. Most of the titanium-containing compounds are located in the pearlite matrix, with some in the steadite and carbides. The results suggest that titanium-containing compounds reduce tool lifetime.     

多校区图书典藏分配工作探讨

分析了多校区情况下典藏分配的重要性，介绍了典藏合理分配的目标，探讨了如何做好多校区典藏分配工作。     

概率型活动网络的计算机模拟

尝试将网络计划技术与风险分析结合起来，突破了传统的ＰＥＲＴ网络计划只考虑单一关键线路的限制以及每项活动持续时间均服从β分布的假定。在ＰＥＲＴ中真正引入随机因素，利用计算机模拟技术，对实际复杂系统进行大量的动态模拟，从而获得描述系统特征的数值，为决策提供了科学的依据。     

论云南土壤的地理分布规律

从地带性原则出发，揭示了土壤发生学的本质，并由此阐明了云南省土壤分布的水平，垂直，相性分布规律，从而为该省的土壤科学命名，分类，区别乃至应用提供了科学依据。     

一种异养生物膜密度分布的分形特征

正常生长的异养生物膜密度D随生物膜厚度d增加而变化,D与d之间具有双自然对数拟和关系,可以lnd=DflnD lnm或d=m·D-Df来表示;d=m·D-Df表征了异养生物膜密度的空间变化具有分形特征,其分维数可用豪斯道夫维数表示,豪斯道夫维数Df值的变化反映了生物膜的密度分布特征及生物膜系统演化特征.