一类等式约束优化问题的改进牛顿算法

提出了牛顿方法与预优广义共轭梯度方法相结合的方法(简称为Newton-PGCG)求解库恩-塔克方程组。给出Newton-PGCG算法中预优广义共轭梯度法中预优阵的选取问题及其步数参数的确定原则,并在保证牛顿方法恰二阶收敛的条件下,证明了此算法也具有恰二阶收敛的优点。     

On modal energy in civil structural control

A new control strategy based on modal energy criterion is proposed to demonstrate the effectiveness of the control system in reducing structural earthquake responses. The modal control algorithm combining LQR （linear quadratic regulator） control algorithm is adopted in the discrete time-history analysis. The various modal energy forms are derived by definition of the generalized absolute displacement vector. A preliminary numerical study of the effectiveness of this control strategy is carried out on a 20-storey framed steel structural model. The controlled performance of the model is studied from the perspectives of both response and modal energy. Results show that the modal energy-based control strategy is very effective in reducing structural responses as well as in consuming a large amount of modal energy, while augmentation of additional generalized control force corresponding to the modes that contain little modal energy is unnecessary, as it does little help to improve the controlled structural performance.     

整Dirichlet级数的一些性质

证明了Dirichlet级数g(s)=∑∞n=1anbne-λns,h(s)=∑∞n=1anbn-1e-λns和f(s)=∑∞n=1ane-λns(s=δ+it)在一定条件下有相同的级、下级、型和(p,q)(R)-级及下(P,q)(R)-级.     

What to post? Understanding engagement cultivation in microblogging with big data-driven theory building

This paper examines how alternative food networks (AFNs) cultivate engagement on a social media platform. Using the method proposed in Kar and Dwivedi (2020) and Berente et al. (2019), we contribute to theory through combining exploratory text analysis with model testing. Using the theoretical lens of relationship cultivation and social media engagement, we collected 55,358 original Weibo posts by 90 farms and other AFN participants in China and used Latent Dirichlet Allocation (LDA) modeling for topic analysis. We then used the literature to map the topics with constructs and developed a theoretical model. To validate the theoretical model, a panel dataset was constructed on Weibo account and year level, with Chinese city-level yearly economic data included as control variables. A fixed effects panel data regression analysis was performed. The empirical results revealed that posts centered on openness/disclosure, sharing of tasks, and knowledge sharing result in positive levels of social media engagement. Posting about irrelevant information and advertising that uses repetitive wording in multiple posts had negative effects on engagement. Our findings suggest that cultivating engagement requires different relationship strategies, and social media platforms should be leveraged according to the context and the purpose of the social cause. Our research is also among the early studies that use both big data analysis of large quantities of textual data and model validation for theoretical insights.     

平方误差损失函数下广义Pareto分布参数的Bayes估计

本文在参数的先验分布为逆伽玛先验分布条件下研究广义Pareto分布参数的Bayes估计问题,并在平方误差损失函数下,导出了参数的Bayes估计。文末通过Monte Carlo数值模拟试验对极大似然估计和Bayes估计进行了比较。     

广义形态滤波在滚动轴承降噪中的应用

由于传统的形态滤波采用相同的结构元素,会造成输出倚的现象。因此广义形态滤波采用不同的结构元素,即先小后大,然后用信噪比和滤波误差对滤波效果进行衡量,并和传统的形态滤波进行比较,研究表明广义形态滤波具有更高的信噪比和更小的滤波误差。最后用实测的故障信号进行验证,其滤波性能要好于传统的形态滤波,并且只是加、减和取极值,计算方便,具有较好的应用前景。     

关于2—距离空间中压缩型映射的不动点定理

本文在2－距离空间中引进了一类新的广义压缩映射,研究了这类映射的不动点的存在性和唯一性问题。     

Diversity as an opportunity or a challenge? A cross-national study of ethnic diversity and students’ generalized trust

In this study, we explore how ethnic diversity at the macro-level relates to students’ generalized trust by using cross-national data. Our analysis shows a positive relationship between ethnic diversity and generalized trust. This relationship is, however, inverted U-shaped curvilinear rather than linear, indicating that the positive relationship levels off and turns negative. While we also find that students’ educational experiences such as social relations at school are positively associated with generalized trust, ethnic diversity at the macro-level is still the most powerful factor in our analysis predicting students’ generalized trust. Theoretical and practical implications are discussed.     

泛化教育与边界教育——对现行教育理论的反思与改造导论

以对现行教育理论的取样为前提,揭示出现行教育观的“活动——传承”框架及其包括德育论、教学论和管理论在内的整个理论的泛化实质,从对历史变迁过程的叙述与抽象中对其根据与偏执进行反思,在“影响——传承与创新”框架内对其进行了基础性改造。     

亏损矩阵的乘法可交换及其可传递的条件

定义了广义0-若当块及其广义幂,并以它们为工具,探讨了亏损矩阵的乘法可交换条件及其可传递的条件。