基于B方法的应用软件开发

随着应用的发展,计算机系统的一致性和可靠性变得越来越重要. 形式化方法以精确的数学语义为基础,能精确描述系统规范,严格验证规范的性质,从而更好地保证软件的一致性和可靠性. B形式化方法支持从规范说明到代码生成的整个软件开发周期. 在给出基于B方法的开发过程之后,以POS系统的开发过程为例,介绍B方法在实际软件开发中的应用.     

TCP状态非典型变迁的形式化研究

协议的规格说明主要是以自然语言描述的,对其进行形式化的目的是精确描述协议,减少开发人员对协议规格说明理解的偏差.B方法以数学理论为基础,可产生简明、精确、无歧义且可证明的规格说明.B方法的优点使得它适合对协议进行形式化描述和一致性测试。本文详细介绍了使用B方法对TCP状态非典型变迁进行形式化,并据此生成了测试用例,提高了TCP协议一致性测试的质量和可靠性。     

VSOS-HAM:基于Isabelle/HOL的OS内核硬件抽象模型和形式化验证方法研究

形式化方法是保证操作系统设计和实现的正确性的可靠方法.操作系统的形式化设计和验证过程仍然是一个极其复杂的过程.由于汇编语言过于底层,对其进行形式化验证的难度较大,如何有效地对汇编语言代码进行建模,便于对其语义和功效的正确性进行验证成为操作系统形式化领域的研究热点.在汇编级提出对操作系统的设计和实现的正确性进行形式化验证的方法.通过建立操作系统内核硬件抽象模型,形式化地描述指令的操作语义,在此内核硬件抽象模型的基础上界定影响系统状态变化的数据对象,建立系统状态空间,结合指令的操作语义的定义来描述系统的状态转换函数.在Isabelle/HOL定理证明器环境中描述该内核硬件抽象模型,以实现的可信操作系统VSOS为例,在汇编级对系统设计和实现的正确性进行验证.结果表明,该方法是可行的和高效的.     

TOP状态非典型变迁的形式化研究

协议的规格说明主要是以自然语言描述的,对其进行形式化的目的是精确描述协议,减少开发人员对协议规格说明理解的偏差,B方法以数学理论为基础,可产生简明、精确、无歧义且可证明的规格说明,B方法的优点使得它适合对协议进行形式化描述和一致性测试。本文详细介绍了使用B方法对TCP状态非典型变迁进行形式化,并据此生成了测试用例,提高了TCP协议一致性测试的质量和可靠性。     

模型驱动的Dafny程序形式化生成与自动验证

Dafny是一种内置规范结构的编程语言和静态程序证明器,它能验证程序的功能正确性以及将证明过程自动化,这既提高了软件开发的效率,又极大增强了软件开发的可靠性.该文探索了一种模型驱动的Dafny程序形式化生成的方法.首先,从问题的Radl规约出发,根据规约变换技术得到其Radl算法;然后,根据PAR方法中循环不变式开发新策略得到问题的循环不变式;最后,在Radl算法和循环不变式基础上利用模型等价转换规则生成Dafny程序,并由Dafny证明器自动验证其功能正确性.用该方法解决了2个典型问题的算法程序开发与验证,证实了该方法能够有效地提高Dafny程序的生成效率和可靠性.     

图搜索问题算法推导及形式化证明

用非形式化方法解决图搜索问题规模受限,对于一些复杂问题难以保证其正确性.传统的形式化方法推导图搜索问题难以理解且不易于形式化证明,现有形式化方法对这类问题的解决方案较少,在保证可靠性和正确性方面有欠缺.该文通过对图搜索问题的深入研究,开发出一种针对解决图搜索算法的新方法.首先刻画问题的规约,利用循环不变式的递归定义技术给出了开发图搜索问题循环不变式的新策略,在此基础上得到Apla抽象算法程序,并对该算法程序进行了形式化证明,再将已验证的Apla算法程序自动生成C++可执行程序,实现了从抽象的形式规约推演出具体的面向计算机的程序代码的程序精化完整过程.以拓扑排序和广度优先遍历为例对所提方法进行实验,实验结果验证了所提方法的有效性,不仅可以推导和证明已知算法,而且对未知算法的推导也有指导性作用.     

基于PVS的数据库安全策略形式化分析方法

基于安全策略模型的形式化分析对于数据库管理系统达到高安全保障等级的重要性,提出了新的基于PVS的数据库安全策略模型分析方法,该方法结合了PVS函数式语言的特点,通过一系列算法和流程展示了模块化的系统状态、安全属性、操作规则的定义过程.借助PVS定理证明器对BeyonDB数据库管理系统进行安全性分析,结果表明,该方法不但能够提高形式化建模效率,而且可以有效地发现系统设计中存在的漏洞.     

基于混成自动机的CPS行为建模与属性验证

系统实时性、安全性和可靠性等非功能属性是信息物理系统在诸多领域应用的关键因素。论文在分析CPS模型构建与分析验证中面临的挑战的基础上,提出了一种CPS行为建模与属性验证方法。该方法首先基于混成自动机对CPS的行为进行建模,然后将此模型转换为混合程序模型,最后在定理证明器KeYmaera中对HP模型的属性进行形式化验证。文中论述了行为模型描述语言的结构,建立了混成自动机模型与HP模型之间的转换规则,分析了模型转换的一致性。应用实例表明:该方法既能简单直观地描述CPS动态行为,又能对CPS的属性进行严格的形式化验证,且有效避免了形式化验证中的状态空间爆炸问题。     

一种具有容错机制的MapReduce模型研究与实现

针对传统MapReduce模型的容错机制对错误的处理效率低下等问题,提出了一种基于多核虚拟机的具有容错机制的MapReduce模型。该模型使用检查点机制进行错误恢复,并只对中间结果和必要的状态信息进行保存;利用虚拟机在隔离内存中保存中间结果;根据用户的需要及系统的负载情况动态调整系统中工作节点的个数。通过在SUN的32核、主频为2.38GHz、内存为128GB服务器上的测试,结果表明:与传统MapReduce模型相比,改进MapReduce模型降低了通信上的开销,提高了MapReduce运行过程的可靠性和错误恢复的性能,虚拟机监控器可以完全控制和管理多核平台的内存,使操作系统无法直接访问隔离的内存,数据恢复不会受到操作系统内部各种错误的影响,保证了恢复数据的安全性。     

信牌驱动式Web工作流管理系统计算模型

近年来,随着计算机和网络的广泛使用,支持复杂业务过程,以实现业务流程自动化为目标的工作流管理系统引起了越来越多的关注。工作流的自动化执行有赖于对业务流程的形式化描述,以保证流程参与者之间的协同工作以及数据的一致性和过程的可靠性。因此流程建模(过程定义)是实现整个工作流管理系统的关键。本文提出了一种新的业务流程描述模型-信牌驱动式工作流计算模型,它是一个基于Web的工作流管理系统的理论基础。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with