中美贸易摩擦的新变化、原因及对策

介绍中美贸易摩擦的一些新变化,并从经济和非经济因素方面进一步分析中美贸易摩擦的原因,提出解决中美贸易摩擦的对策。     

关于声发射法在塑性加工中应用的研究——塑性加工界面摩擦润滑状态的分析(Ⅱ)

本文用声发射法分析了塑性加工界面摩擦润滑状态。得到了金属拉拔时,声发射事件总数与拉拔速度,断面收缩率,润滑油粘度之间的关系。从声发射参数的变化,可看出界面状态变化的情况。因此,用声发射法可对塑性加工界面上的摩擦润滑状态的变化,进行动态下实时监测,进而可为产品的加工质量监控,提供新的方法。     

On the block structure of proper block designs

In this paper we consider proper block designs and derive an upper bound for the number of blocks which can have a fixed number of symbols common with a given block of the design. To arrive at the desired bound, a generalization of an integer programming theorem due to Bush (1976) is first obtained. The integer programming theorem is then used to derive the main result of this paper. The bound given here is then compared with a similar bound obtained by Kageyama and Tsuji (1977).     

Complete designs with blocks of maximal multiplicity

The set of distinct blocks of a block design is known as its support. We construct complete designs with parameters v(?7), k=3, λ=v ? 2 which contain a block of maximal multiplicity and with support size $\text{b}{}^1\text{= (}{}^{\mathrm{v}}{}_3\text{) ? 4(v ? 2)}$. Any complete design which contains such a block, and has parameters v, k, λ as above, must be supported on at most (^v₃) ? 4(v ? 2) blocks. Attention is given to complete designs because of their direct relationship to simple random sampling.     

Approximation of power in multivariate analysis

We consider the calculation of power functions in classical multivariate analysis. In this context, power can be expressed in terms of tail probabilities of certain noncentral distributions. The necessary noncentral distribution theory was developed between the 1940s and 1970s by a number of authors. However, tractable methods for calculating the relevant probabilities have been lacking. In this paper we present simple yet extremely accurate saddlepoint approximations to power functions associated with the following classical test statistics: the likelihood ratio statistic for testing the general linear hypothesis in MANOVA; the likelihood ratio statistic for testing block independence; and Bartlett's modified likelihood ratio statistic for testing equality of covariance matrices.     

基于SolidWorks及ANSYS对集成块优化设计

为解决复杂液压阀块在传统设计制造过程中工作量大、易出错、效率低等困难,采用SolidWorks三维软件对其进 行设计和前处理,可提高工作效率,减轻工作强度。再结合ANSYS分析软件,对集成块进行强度应力分析,以保证制品 的可靠性。最终使阀决达到集成化程度高、性能优越的特点,达到优化设计的目的。     

中美经贸摩擦及其对美国在华企业的影响

中美经贸摩擦的主要表现是美国不断对中国的出口产品加征关税。在估算中美经贸摩擦对美国在华企业的影响后认为,由于美国在华企业在美国整体利益格局中占比较小,产品出口比例较小及其行业分布的特点,导致中美经贸摩擦对美国在华企业的影响十分有限,但这也意味着美国在中国的直接投资不会大量减少。中国应准确把握和平衡好利用在华美资企业牵制美国政府的应对措施,通过更高水平的扩大开放来应对中美经贸摩擦。     

Optimal block designs for double cross experiments

ABSTRACT

This paper presents systematic methods of construction of optimal block designs for a double cross experiments for both even and odd values of “p” parental lines. The both even and odd values of designs are derived by using initial block of unreduced balanced incomplete block designs and initial block of row–column designs given by Bose et al. (1953 Bose, R.C., Shrikhande, S.S., Bhattacharya, K.N. (1953). On the construction of group divisible incomplete block design. Ann. Math. Stat. 24:167–195.[Crossref] , [Google Scholar]) and Gupta and Choi (1998 Gupta, S., Choi, K.C. (1998). Optimal row-column designs for complete diallel crosses. Commun. Stat. Theory Methods 27(11):2827–2835.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]), respectively. In this attempt we have found some new universally optimal block designs for double cross experiments.     

Constructions of efficiency-balanced designs

We present a number of methods of constructing efficiency-balanced binary block designs which are design patterns for simplification of statistical analysis. Furthermore, a method of construction of an efficiency-balanced block design with v+1 treatments from one with v treatments is generally characterized.     

Type a incomplete multi-response designs

Srivastava considered the problem of designing and analysis of incomplete multi-response experiments, The main characteristics of the analysis given by her are investigated and a general class of incomplete multiresponse designs (Type A) is obtained on the basis of these investigations.