浅谈模具制造工艺教学

文章针对模具制造工艺课程的教学特点 ,结合作者在教学实践中的体会 ,提出通过精选教学内容、采用灵活多样的教学方法及加强教师自身修养等方面的努力 ,提高教学质量 ,增强模具专业应用型人才对社会的适应性。     

向死而生：论“贵生”教育之生死二律背反

＂死＂具有丧失生命之生物学意义、有当下之否定社会哲学意义、有生命升华和虚无的三层的语义。＂死＂亦具有客观性、复杂性、不可逆性和确定与不确定相反相成之属性。从悖论角度指认＂贵生＂教育的生死之二律背反,明晰其矛盾归属,释放生命智慧,网织死亡境界,完成爱和美的绝对永恒信仰。     

Identities and inequalities for the expected values of random matrices and loewner's theory

We consider the identity associated with the expected values of the matrix-valued quadratic forms of two random matrices. As a special case the identity yields the matrix-valued inequality of the Schwarz type. The most important application is for Loewner's theory in the context of the operator-monotone function, and the inequalities based on the concavityconvexity of the matrix-valued functions are derived.     

Efficient computation of the cdf of the maximal difference between a Brownian bridge and its concave majorant

In this paper, we describe two computational methods for calculating the cumulative distribution function and the upper quantiles of the maximal difference between a Brownian bridge and its concave majorant. The first method has two different variants that are both based on a Monte Carlo approach, whereas the second uses the Gaver–Stehfest (GS) algorithm for the numerical inversion of the Laplace transform. If the former method is straightforward to implement, it is very much outperformed by the GS algorithm, which provides a very accurate approximation of the cumulative distribution as well as its upper quantiles. Our numerical work has a direct application in statistics: the maximal difference between a Brownian bridge and its concave majorant arises in connection with a nonparametric test for monotonicity of a density or regression curve on [0,1]. Our results can be used to construct very accurate rejection region for this test at a given asymptotic level.     

基于MasterCAM的模具数控加工过程分析与应用

模具零件因其复杂的空间形面和形面特征而广泛采用数控加工方式。以常见的凹槽模具为例，基于MasterCAM对其数控加工过程进行了分析和参数设定。运用不同铣削方法完成了粗、精加工程序的编制与仿真，分析比较了典型的粗、精加工组合方式的加工质量和加工时间，确定了合理、高效的铣削方法。旨在探索一种优质、高效的数控加工方法，保汪加工精度和质量、缩短产品生产周期、降低加工成本。     

新形势下模具专业综合实验教学改革探索与实践

文章分析了"模具专业综合实验"教学面临的新问题,提出了教学改革实施方案,介绍了专业综合实验的特色与实施效果,并提出了进一步完善的建议。实践表明:专业综合实验可提高学生的综合素质、创新能力和工程实际能力。     

孙坚的崛起与战死考

孙坚是在东汉末年特定的历史背景下崛起的，在镇压黄巾起义与军阀混战的过程中逐步成为地方武装强人。他参与讨伐董卓并斩杀其都督华雄，后来又被刘表部将黄祖的部曲兵射杀于岘山。但作为孙吴政权的奠基人，其事业后继有人。     

拉拔新技术

本文介绍了反张力拉拔，辊式模拉拔，强制润滑拉拔，无酸拉拔，超塑性拉拔等新技术，这些是国内外正在研究或已实际应用的新工艺，对解决拉拔工艺的高能问题有较高的理论与实用价值，此外还介绍了高生产率的新型拉拔设备。     

一类新的数据变换及其对提高灰预测精度的有效性研究

提出了经过非负函数cg(x)+d变换来提高GM(1,1)模型的预测精度,并从理论上证明,这类变换为级比偏差压缩变换,保证了数据变换后的序列有非负上凹的特性,还原后的误差不会增大等性质,并通过实例对比说明了这种变换的有效性。     

Sparse optimization for nonconvex group penalized estimation

We consider a linear regression model where there are group structures in covariates. The group LASSO has been proposed for group variable selections. Many nonconvex penalties such as smoothly clipped absolute deviation and minimax concave penalty were extended to group variable selection problems. The group coordinate descent (GCD) algorithm is used popularly for fitting these models. However, the GCD algorithms are hard to be applied to nonconvex group penalties due to computational complexity unless the design matrix is orthogonal. In this paper, we propose an efficient optimization algorithm for nonconvex group penalties by combining the concave convex procedure and the group LASSO algorithm. We also extend the proposed algorithm for generalized linear models. We evaluate numerical efficiency of the proposed algorithm compared to existing GCD algorithms through simulated data and real data sets.