The NHS as a proving ground for cryptosystems

This paper examines the challenges that the National Health Service poses as an environment for public key cryptography systems.The NHS is Europe’s largest single employer, with over 1.2 million staff. It provides lifetime healthcare for most of its population, and has done so for 55 years. In the last decade, it has launched several major programmes to develop NHS-wide information systems.Just the scale of the NHS is daunting. But systems that handle patients’ medical records are subject to a plethora of laws, policies, guidelines and practices for controlling the access, use and storage of the information. Taken together, the rules are complex and sometimes contradictory and, in addition, must be balanced against both patients’ express wishes and their clinical needs.Cryptography is an obvious means to secure and protect confidential information. Recently, identity-based public key cryptography schemes not only seem easier to deploy than previous schemes, but also seem equal to the challenges. In this paper, we give a detailed overview of the features and challenges that the NHS environment presents to uses of cryptography, to qualify our impressions of our cryptosystem and to guide our future efforts to develop it.     

基于MotionView整车虚拟试验场仿真的后转向节强度分析

由于车辆行驶状况复杂多样,传统静态工况无法复现各类恶劣路况下后底盘转向节真实应力,因此在利用MotionView建立整车刚柔耦合多体动力学模型的基础上,将后转向节利用柔性体进行模拟;在进行虚拟试验场仿真分析的同时采用模态综合法计算结构动应力,得到后转向节最高应力位置及发生时刻.仿真结果与整车道路试验结果的对比表明仿真方法准确.     

Theorem proving with abstraction

A class of mappings called abstractions are defined, and examples of abstractions are given. These functions map a set S of clauses onto a possibly simpler set T of clauses. Also, resolution proofs from S map onto possibly simpler resolution proofs from T. In order to search for a proof of a clause C from S, it suffices to search for a proof from T and attempt to invert the abstraction mapping to obtain a proof of C from S. Some theorem proving strategies based on this idea are presented. Most of these strategies are complete. A method of using more than one abstraction at the same time is also presented. This requires the use of ‘multiclauses’, which are multisets of literals, and associated ‘m-abstraction mappings’ on multiclauses. Certain abstractions are especially interesting, because they correspond to particular interpretations of the set S of clauses. The use of abstractions permits the advantages of set-of-support strategies to be realized in arbitrary complete non set-of-support resolution strategies.     

Program proving: Coroutines

Summary Proof methods adequate for a wide range of computer programs have been given in [1–6]. This paper develops a method suitable for programs which incorporate coroutines. The implementation of coroutines described follows closely that given in SIMULA [7, 8], a language in which such features may be used to great advantage. Proof rules for establishing the correctness of coroutines are given and the method is illustrated by the proof of a useful program for histogram compilation.     

Completely non-clausal theorem proving

The proof procedure we describe operates on quantifier-free formulas of the predicate calculus which are not truth-functionally normalized in any way. The procedure involves a single inference rule called NC-resolution, and is shown to be complete. Completeness is also obtained for a simple restriction on the rule's application.Examples are given using NC-resolution to derive a logic program from its specification, and to ‘execute’ a program specification in its original form.