连续介质分析动力学及其应用

综述了国内和国外学者研究连续介质分析动力学问题的进展,阐明了本文主要论述将Lagrange方程应用于连续介质动力学的问题.论文采用Lagrange-Hamilton体系,分别论述了非保守非线性弹性动力学、不可压缩黏性流体动力学、黏弹性动力学、热弹性动力学、刚–弹耦合动力学和刚–液耦合动力学的Lagrange方程及其应用.论述了应用Lagrange方程建立有限元计算模型的问题.最后,展望了将Lagrange方程应用于连续介质动力学问题的研究前景.

航天刚-弹-液耦合系统的弹-液耦合研究

航天刚-弹-液耦合动力学中的弹-液耦合问题是关系到航天刚-弹-液耦合系统液固耦合机理研究和大规模液固耦合建模计算研究的重要课题。通过分析刚-弹-液耦合动力学拟变分原理的泛函,说明刚-弹-液耦合中的刚-弹耦合、刚-液耦合和弹-液耦合的特点。应用Lagrange乘子法,将无际边界条件纳入泛函中,通过识别Lagrange乘子,逐步说明弹-液耦合的机理。通过对泛函求驻值发现,无际边界条件由原来的先决条件转化为驻值条件,实现了从协调元到杂交元的过渡。通过分析泛函识别Lagrange乘子前后的驻值条件,明确了识别La-grange乘子可以有效地减少计算自由度。

非保守非线性刚-热-弹耦合动力学的Lagrange方程

如何将Lagrange方程应用于弹性动力学,一直是国内外学术界关注的理论和应用研究课题.在这类问题获得基本解决之后,Lagrange方程应用于耦合动力学的理论难题又摆在我们的面前.本文采用Lagrange Hamilton体系,成功地将Lagrange方程应用于非保守非线性刚 热 弹耦合动力学.进而应用非保守非线性刚 热 弹耦合动力学的Lagrange方程推导出非保守非线性刚 热 弹耦合动力学的控制方程.讨论了应用耦合动力学的Lagrange方程解决实际工程技术问题的途径.

大中城市医护人员关于碘缺乏网络舆情的调查分析

目的了解大中城市医护人员对碘缺乏危害的认知水平，对加碘食盐的态度和食用情况，为今后防治碘缺乏的健康教育提供依据。方法采用自编问卷，借助问卷星平台形成问卷发布并收集结果，调查时限为2017年5月6日至6月6日；最终回收有效问卷481份，其中女性和男性各占63．8％（307／481）和36．2％（174／481）；采用SPSS22．0软件进行数据分析，采用二元logistic回归分析选择未加碘食盐的影响因素，用后退法筛选出有统计学意义（P〈0．05）的影响因素。结果90．4％（435／481）的医护人员知道智力低下是碘缺乏危害之一，72．8％（350／481）的人指出碘缺乏最严重的危害是儿童智力低下。尽管本调查涉及地区均存在碘缺乏，仍有55．5％（267／481）的人认为自己生活的地区不缺碘；41．0％（197／481）的人认为沿海居民不需要食用碘盐；有15．6％（75／481）的人认为目前人群碘营养处于碘过量。选用坚持食用碘盐的人占7613％（367／481），9．6％（46／481）的人选择食用未加碘食盐，14．1％（68／481）的人选择交替食用碘盐与未加碘食盐。logistic回归分析结果显示，阻碍医护人员选择加碘食盐的因素是“受访者所在地区为沿海地区”、“认为自己碘营养充足”、“知道缺碘会影响子女发育但仍坚持食用未加碘食盐”：促进医护人员选择加碘食盐的因素是“坚持购买碘盐．不会选择未加碘食盐”，其中有75．8％（238／314）的人知道碘缺乏病最严重的危害是智力低下。结论大多数医护人员具有较高的碘缺乏病防治知识；但信息缺乏或片面，“沿海地区不缺碘”和担心“碘过量造成甲状腺疾病或癌症”观念阻碍了主动食用碘盐。对医护人员的健康教育，更应当通过专业渠道，警示环境缺碘的信息，并分享防治工作、碘盐安全性、甲状腺癌与甲状腺疾病最新的研究进展。

Quasi-variational principles of single flexible body dynamics and their applications

The reasons for studying single flexible body dynamics are that on one hand,it is the basis of flexible multi-body dynamics.If the theory of the single flexible body dynamics has been deeply studied,the theory of flexible multi-body dynamics will be researched easily.On the other hand,it has its unique and important applications.Quasi-variational principle of non-conservative single flexible body dynamics is established under the cross-link of particle rigid body mechanics and deformable body mechanics.Taking the interceptor as an example,this paper has explained the physical meaning of the quasi-stationary value condition of the quasi-variational principle in non-conservative single flexible body dynamics.Taking the launch of rocket as an example,it has illustrated the features of"one force for two effects"in a single flexible body dynamics.With an example of the extending flexible beam coupled with the spacecraft attitude,it has shown the transition from the single flexible body dynamics to the flexible multi-body dynamics.Finally,a number of related problems are discussed.

Non-linear and non-conservative quasi-variational principle of flexible body dynamics and application in spacecraft dynamics

The law of conservation of energy is one of the most fundamental laws of nature.According to the law of the conservation of energy,the non-linear and non-conservative quasi-variational principle of flexible body dynamics is established.The physical meaning of the quasi-stationary value conditions has been explained in non-linear and non-conservative flexible body dynamics.In the case study,the application in spacecraft dynamics is researched.

Application of Lagrange＇s equation to rigid-elastic coupling dynamics

A consistent focus in theoretical mechanics has been on how to apply Lagrange's equation to continuum mechanics.This paper uses the concept of a variational derivative and its laws of operation to investigate the derivation of Lagrange's equation,which is then applied to nonlinear elasto-dynamics.In accordance with the work-energy principle and the energy conservation law,kinetic and potential energies are proposed for rigid-elastic coupling dynamics,whose governing equation is established by manipulating Lagrange's equation.In addition,case studies are used to demonstrate the application of the proposed method to spacecraft dynamics.

Unconventional Hamilton-type variational principles for analytical mechanics

According to the basic idea of classical yin-yang complementarity and modern dual-complementarity, in a simple and unified new way proposed by Luo, the un-conventional Hamilton-type variational principles of holonomic conservative system in analytical mechanics can be established systematically. This unconventional Hamilton-type variational principle can fully characterize the initial-value problem of analytical mechanics, so that it is an important innovation for the Hamilton-type variational principle. In this paper, an important integral relation is given, which can be considered as the expression of the generalized principle of virtual work for analytical mechanics in mechanics. Based on this relation, it is possible not only to obtain the principle of virtual work of holonomic conservative system in analytical mechanics, but also to derive systematically the complementary functionals for three-field and two-field unconventional variational principles, and the functional for the one-field one by the generalized Legendre transformation given in this paper. Further, with this new approach, the intrinsic relationship among various principles can be explained clearly. Meanwhile, the unconventional Hamilton-type variational principles of nonholonomic conservative system in analytical mechanics can also be established systematically in this paper.