基础隔震结构不确定参数敏感性分析

隔震结构系统参数的不确定性和地震的随机性可能会导致结构响应意想不到的偏移,导致大幅减少安全性评价的准确度和精密度,因此有必要探究隔震支座的不确定性因素对结构响应的影响。本文着重研究基础隔震钢筋混凝土结构的不确定性因素,包括结构的不确定性和地震作用的不确定性。采用龙卷风图对结构不确定参数进行敏感性分析,并对比隔震与非隔震结构的参数敏感性;提出基于我国国情的双响应面法,利用响应面模型同时考察地震动和基础隔震结构的不确定性对地震响应的影响。结果表明:隔震技术可以减小结构不确定性的影响并且地震动的不确定性对结构的影响大大超过结构本身的不确定性。

如何确保英语考题质量

本文论述保证考题质量的必要性.它包括试题指令的准确简明、内容的复盖面、多项选择题正确答案的唯一性,干扰项应真正具有干扰力、正确答案的随机性等.

“Random-任务驱动教学法”在养禽学实验教学中的应用

为了增强学生学习的主观能动性,提高其知识的综合应用和解决实际问题的能力,培养其实践能力和创新能力,笔者结合养禽学实验教学特点,按照"Random-任务驱动教学法"的要求,对实验教学方法进行改革。结果表明:通过改革拓宽了学生的知识面,完善了学生的知识体系,提高了学生独立思考、分析问题和解决问题的能力,同时也提高了教师的综合素质,收到了较好的实验教学效果,有助于培养学生的实践能力和创新能力。

快速平滑收敛策略下基于QS-RRT的UAV运动规划

基于快速扩展随机树(rapidly exploring random tree,RRT)的运动规划算法,通过随机采样的方式探索未知任务空间,具有概率完备性和较高的计算效率.该类算法在应用于无人机运动规划时必须对飞行距离、过程安全性和航路平滑度进一步优化.针对这一问题,首先对威胁环境、无人机运动学性能和探测能力建模,然后根据飞行特征设计了随机采样、威胁规避、路径可跟踪性以及全局与局部平滑性等优化策略,并构建快速平滑收敛RRT(quick and smooth convergence RRT,QS-RRT),最后以此为基础分别提出了面向已知和未知任务空间的无人机运动规划算法.仿真结果表明,该算法能够在保证飞行路径收敛性、安全性及其规划效率的基础上,有效缩短飞行距离,改善航路的可跟踪性和平滑度,增强在实际飞行过程中的可操作性.此外,该算法还易于在航路优化效果和规划效率之间权衡,增强了对不同规划任务需求的适应性.

Effects of Feiwei granules in the treatment of idiopathic pulmonary fibrosis:a randomized and placebo-controlled trial

OBJECTIVE： To document the therapeutic effects of Feiwei granules （FGs） for idiopathic pulmonary fi-brosis （IPF）.METHODS： One hundred cases with IPF were ran- domized into the treatment group （80） and control group （20）. Both groups were given basic treat- ment with prednisone. The treatment group was given FGs, and the control group was given Jinshui- bao capsules （JCs）. Treatment lasted for 6 months. The Medical Research Council Dyspnea Scale （MRCDS）, the Saint George＇s Hospital Respiratory Questionnaire （SGHRQ）, pulmonary function, the Traditional Chinese Medicine Syndrome Score （TC- MSS）, 6-min walking test （6MWT） and blood gas analyses were recorded before the study as well as 3 months and 6 months after treatment.RESULTS： FGs showed greater efficacy than the control in certain parameters between before the study and 6 months, and between 3 months and 6 months, in the MRCDS, some indicators in the SGHRQ, and the TCMSS. There were no significant differences between the treatment group and con- trol group in the remainder of the indices evaluat- ed. In the treatment group, there were significant differences in before and after treatment in the MRCDS, SGHRQ, TCMSS and 6MWT.

α稳定分布对称系数和分散系数估计方法

研究了α稳定分布的对称参数和分散系数估计问题,分别提出了基于极限特征的对称参数估计方法和用于估计分散系数的基于概率分布函数的半概率法.首先介绍了α稳定分布的定义和极限特征,并根据极限特征提出一种估计对称参数β的方法,该方法利用α稳定分布的左极限概率与右极限概率的比值来估计β.介绍了α稳定分布的概率分布函数,分析了概率分布函数的性质,并指出当α>1时,半概率点与γ之间有紧密的联系,并利用这一联系,提出一种估计γ的半概率方法.通过仿真实验验证了以上两种估计方法,结果表明:基于极限特征的对称参数估计方法当α<1.8时多数情况下估计误差小于0.05,半概率方法对γ的估计误差小于0.02.

Use of N,O-carboxymethyl chitosan to prevent postsurgical adhesions in a rabbit double uterine horn model： a randomized controlled design

In previous studies, N,O-carboxymethyl chitosan has been shown to decrease the incidence and intensity of abdominal adhesions. In the present study, adhesions were induced in 220 rabbits using a double uterine horn model. Rabbits were randomized to receive an operation only or an operation+medical chitosan intraperitoneally. Twenty-two rabbits from each group were euthanized at one of five different times(Day 3, 7, 14, 28, or 42), and adhesion formation was given gross and histopathological scores. Reductions were observed in adhesion extent(P=0.0337) and tenacity(P=0.0271) as well as inflammation(P<0.0001) on Day 3 when medical chitosan was applied. Prior to Day 14, fibrosis was less obvious in the medical chitosan group(P<0.0005). The tenacity scores were significantly lower in the medical chitosan group following Day 14(P<0.05), while the type scores were lower in the medical chitosan group following Day 28(P<0.03). Thus, medical chitosan decreased both the gross and the histopathological scores of the induced adhesions.