考虑主系统阻尼的减振镗杆设计与实践

用直径φ130mm的镗杆镗削油缸孔,在较小的切削深度切削时仍产生颤振,这严重地限制了产品质量和生产率的提高。针对这一情况,作者测量了有关参数,设计出具有阻尼动力减振器的大直径镗杆,设计时考虑了以往人们为简化问题而忽略的主系统阻尼,并以动柔度负实部为目标。由SD—375动态分析仪等设备对切削试验测信号进行分析、处理,其结果验证了理论的正确性,并反映出明显的减振效果     

正确软件开发的集成式设计支持环境

本文介绍了国外特别是德国在正确软件开发支持系统方面的进展，重点阐述集成了各种方法学语言及正确性证明逻辑的集成式正确软件开发支持系统（ＫＯＲＳＯ），它的系统特点、形式机制及系统组织体系。     

篮球篮板球的重要性及其争抢技巧的训练

阐述篮板球的重要性,介绍和分析了争抢篮板球的练习方法和技巧。     

防火涂层的研制

本文阐述了国内外防火剂的进展和在国民经济中的意义。并介绍了防火涂料的研制与应用。     

改性聚乙烯发泡体阻燃性研究

本文对含氯聚合物改性的 LDPE 发泡体的阻燃性进行了研究。讨论了LDPE/CPE 并用比、LDPE/CPE/PYC 并用比和不同阻燃剂对发泡体阻燃性和物理性能的影响。实验表明,LDPE/CPE/PVC 三元共混体与Cl一Wax/Sb_2O_3阻燃剂并用可得到较好的阻燃效果和良好物性的发泡体。     

云南城市抗震防灾能力现状分析及抗震对策措施建议

本文根据澜沧—耿马地震震害的调查和东川、丽江等八市(县)城市综合抗震防灾能力的研究结果为主要依据,对云南省城市抗震防灾能力的现状进行了初步的分析与估计,并就减轻城市地震灾害的对策、措施提出了若干建议。     

A New Implementation of Automath

This paper presents aut, a modern Automath checker. It is a straightforward re-implementation of the Zandleven Automath checker from the seventies. It was implemented about five years ago, in the programming language C. It accepts both the AUT-68 and AUT-QE dialects of Automath. This program was written to restore a damaged version of Jutting's translation of Landau's Grundlagen. Some notable features: It is fast. On a 1 GHz machine it will check the full Jutting formalization (736 K of nonwhitespace Automath source) in 0.6 seconds. Its implementation of -terms does not use named variables or de Bruijn indices (the two common approaches) but instead uses a graph representation. In this representation variables are represented by pointers to a binder. The program can compile an Automath text into one big Automath single line-style -term. It outputs such a term using de Bruijn indices. (These -terms cannot be checked by modern systems like Coq or Agda, because the -typed -calculi of de Bruijn are different from the -typed -calculi of modern type theory.)The source of aut is freely available on the Web at the address .     

External Rewriting for Skeptical Proof Assistants

This paper presents the design, the implementation, and experiments of the integration of syntactic, conditional possibly associative-commutative term rewriting into proof assistants based on constructive type theory. Our approach is called external because it consists in performing term rewriting in a specific and efficient environment and checking the computations later in a proof assistant. Two typical systems are considered in this work: ELAN, based on the rewriting calculus, as the term rewriting-based environment, and Coq, based on the calculus of inductive constructions as the proof assistant. We first formalize the proof terms for deduction by rewriting and strategies in ELAN using the rewriting calculus with explicit substitutions. We then show how these proof terms can soundly be translated into Coq syntax where they can be directly type checked. For the method to be applicable for rewriting modulo associativity and commutativity, we provide an effective method to prove equalities modulo these axioms in Coq using ELAN. These results have been integrated into an ELAN-based rewriting tactic in Coq.     

Lower Bounds for the Weak Pigeonhole Principle and Random Formulas beyond Resolution

We work with an extension of Resolution, called Res(2), that allows clauses with conjunctions of two literals. In this system there are rules to introduce and eliminate such conjunctions. We prove that the weak pigeonhole principle PHP^cn_n and random unsatisfiable CNF formulas require exponential-size proofs in this system. This is the strongest system beyond Resolution for which such lower bounds are known. As a consequence to the result about the weak pigeonhole principle, Res(log) is exponentially more powerful than Res(2). Also we prove that Resolution cannot polynomially simulate Res(2) and that Res(2) does not have feasible monotone interpolation solving an open problem posed by Krají ek.     

ACJT群签名方案中成员撤消的高效实现

成员撤消问题是设计群签名方案中的一个难题,到目前为止尚无满意的解决办法.在ACJT群签名方案的基础上,提出了新的成员撤消方法.在新方案中,管理员在撤消一个成员时仅需要一次乘法运算来更新群公钥,签名和验证算法的计算量均独立于目前群成员个数和被撤消的成员个数,因而算法是高效的.以前的具有撤消成员功能的群签名方案,签名和验证算法的计算量要么依赖当前的群成员个数,要么依赖被撤消的群成员个数,而且群公钥的更新或者成员密钥的更新往往需要多次指数运算.