Potential theory method for 3D crack and contact problems of multi-field coupled media: A survey

This paper presents an overview of the recent progress of potential theory method in the analysis of mixed boundary value problems mainly stemming from three-dimensional crack or contact problems of multi-field coupled media. This method was used to derive a series of exact three dimensional solutions which should be of great theoretical significance because most of them usually cannot be derived by other methods such as the transform method and the trial-and-error method. Further, many solutions are obtained in terms of elementary functions that enable us to treat more complicated problems easily. It is pointed out here that the method is usually only applicable to media characterizing transverse isotropy, from which, however, the results for the isotropic case can be readily obtained. Project (No. 10372088) supported by the National Natural Science Foundation of China     

钢球撞击双层带间隙保护板炸药柱的爆炸分析

采用LS-DYNA3D动力有限元程序对钢球撞击双层带间隙保护板炸药柱的爆炸过程进行了数值模拟分析。分析中采用了流固耦合与动力学接触模式,获得了钢球撞击的临界起爆速度,爆炸产生的峰值压力。研究表明,采取适当的保护措施,炸药制成的部件或装置的安全性能够得到保证。     

一个强耦合捕食模型正解的先验估计

讨论了一个强耦合的Holling-Tanner型捕食模型,利用Harnack不等式和最大值原理给出了它正解的上、下界估计.     

LCL-S型ICPT系统输出电压特性分析与设计

针对很多无线供电应用场合需要保持输出电压恒定的需求,提出了一种高频逆变器前动态调压的恒压输出控制方法。以LCL-S型感应耦合电能传输系统为研究对象,通过阻抗分析法建模,发现通过元器件的参数配置,可使系统输入阻抗为纯阻性,减少无功分量,同时逆变器开关管实现了零电流开通与关断,但此时系统输出电压并不恒定。针对分析结果提出基于模糊自适应PI控制算法的逆变前动态调压控制的恒压输出控制方案,最后搭建了仿真实验平台和实验样机证明了分析结果的正确和控制方案的有效。     

Headteacher as a Pedagogical Leader: a Comparative Study of Headteachers in Sweden and England

ABSTRACT

This is a comparative study, drawing on data obtained from interviews conducted with headteachers, that compares the roles of Swedish and British headteachers as pedagogical leaders. For its analytical framework the study uses the qualitative research approach known as phenomenography and, in the context of the guiding legal documents related to education, examines the study's findings as frame factors and as tight and loosely coupled systems. Based on interviews with the study's subjects (five Swedish and five English headteachers), discernible differences were noted between Swedish and English headteachers in their roles as pedagogical leaders. Both groups are responsible for the administration and management of the school but, compared to the Swedish headteachers, their English counterparts have greater personal responsibility for the school's overall performance and are more focused on providing leadership in teaching and learning. In contrast, the Swedish headteachers had a greater separation of the two roles, with the headteacher taking responsibility for administration and leaving responsibility for teaching and learning to the teachers.     

四阶色散对光纤参量放大器增益特性的影响

利用数值求解非线性耦合方程,研究了四阶色散对于单泵浦光纤参量放大器增益的影响．计算表明,通过优化泵浦波长和四阶色散值,可以获得大的平坦带宽或者特殊的应用．分析了在大信号输入时对应增益的变化,发现对于泵浦波长大于零色散波长且四阶色散为正值的增益谱影响最大．     

电感耦合等离子体原子发射光谱法测定铁矿石中元素含量

提出了使用电感耦合等离子体原子发射光谱同时测定铁矿石中Al、Ti、Ca、Mg、V含量的分析方法。样品用HCl、HNO3、HF、HClO4溶解,然后在选定的仪器工作条件下测定。使用基体匹配法来校正基体的干扰。各元素的测定检出限为0.006～0.03μg/mL,相对标准偏差(RSD,n=9)为0.6%～4.0%。经国家标准物质验证,测定值与认定值基本相符合。     

越江公路隧道浅埋段地温长期演化的数值预测(英文)

在考虑并行隧道耦合传热的前提下,预测越江公路隧道江岸浅埋段地温的长期演化,使用有限差分法进行数值模拟,通过现场观测与数值迭代方式确定边界条件与初值.模拟结果表明:最终的计算稳定传热时间为68年,但传热在20年内即基本完成;隧道周围的初始恒温土层最终被转变为年变温土层;隧道外侧5 m及两孔之间出现了一个显著变温区,其最大温升值为7.14℃,最大年度温升的峰谷值为10℃;隧道周围10 m以下土层的温度变化仅由隧道传热所控制;两孔之间土层的最终稳定温度要高于其他位置的最终稳定温度,证实了耦合传热效应的存在.此外,还提出了一组单变量函数的回归模型,用以估计隧道周围不同位置土层的年度温度波动量.该研究将有助于深入探究隧道浅埋段所穿越江滩区域工程地质条件的长期演化趋势.     

基于受众画像的新型耦合社交网络谣言传播模型研究

[目的/意义] 移动互联网时代谣言传播模式发生了巨大的变化,一方面谣言的扩散已不再局限于孤立的线下人际关系网络或线上互联网,谣言在耦合网络之间的传播变得更加普遍。另一方面,以往通过概率方式研究谣言的传播存在很大的不准确性,受众的个体特征差异对谣言的传播起到了更重要的作用。本文针对上述现象进行了研究。[方法/过程] 以受众的年龄作为两种网络的耦合依据,提出基于受众年龄的新型谣言传播的耦合社交网络（ASCN）。从受众的认知能力、匿名程度、权威性等基本特征,以及受众的从众心理、记忆效应、好友的影响作用等心理特征方面对受众进行画像,构建多维度函数实现基于受众画像的谣言传播模型。[结果/结论] 基于ASCN对本文提出的模型进行模拟仿真。结果表明,ACSN能够真实地反应出当前网络环境下谣言传播呈现出的"线下引起线上共鸣"、"线上溢散线下"的特征;受众的基本特征和心理特征能够对谣言传播产生巨大的影响,能更好地反映社交网络中谣言的传播规律。     

发电机组轴系弯扭耦合电磁激发振动数学模型

依据机电分析动力学理论 ,找到了发电机组定转子间气隙磁场的能量 ,得到了作用在发电机转子上的电磁力 (矩 ) ,建立了一个基于分段连续质量的发电机组轴系弯扭耦合电磁激发振动的数学模型 .该模型考虑了不平衡、陀螺力矩、转动惯量、剪切变形及阻尼的影响 ,是一个比较精确的模型 .对全面探索发电机组的振动规律具有应用价值