共查询到19条相似文献,搜索用时 125 毫秒
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神经网络的数字VLSI实现中,非线性激活函数是计算部件设计中的难点.区别于其他模拟近似方法,本文提出的LMN方法使用逻辑最小项化简,对查找表(即函数真值表)进行有效压缩,提炼出函数最简逻辑表达式后,可直接生成结构规整的门级电路,且除线延时外,电路只有数个门级延时.该方法使用程序实现,简化了设计过程.结果表明当定点位数小于12时,该方法在速度及误差方面具有更好的性能. 相似文献
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《计算机辅助设计与图形学学报》2017,(3)
针对现有基于传统布尔逻辑进行逻辑级功耗优化的局限性,提出逻辑函数基于传统布尔逻辑和Reed-Muller逻辑的双逻辑门级图形表示的功耗优化方法.首先在逻辑级采用简化有序二叉决策图实现逻辑函数的双逻辑表示;然后通过代数分解和布尔分解获得双逻辑门级表示,进而基于功耗成本估算进行门级功耗优化;最后实现变量级和门级的两层次的优化方法.与学术界著名的ABC和工业界最先进的工具Design Compile(DC)进行比较的实验结果表明,该方法均具有一定的优势. 相似文献
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数字电路硬件描述语言是自动电路设计及自动电路划分不可缺少的工具,在计算机辅助电路测试,计算机辅助电路分析等领域有广泛的应用,本文介绍了一个门级的数字电路硬件描述语言CDL及其编译器的实现过程。一个CDL语言源程序成对一块电路板组件的逻辑功能和物理位置的描述,而CDL语言编译器把CDL语言源程序转换成一组面向测试产生的拓扑数据结构表示。 相似文献
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提出一种时序优化的通用FPGA装箱算法。将配置电路与用户电路转化为有向图,解决子图同构问题。将线网延时作为变量,定义关键度,以此为代价函数进行装箱,达到优化时序的目的。在VPR平台上进行实验,结果表明,该算法的时序性能较优,并可应用于不同的可配置逻辑块结构中。 相似文献
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输入端加译码器的可编程逻辑阵列的复杂性分析 总被引:1,自引:1,他引:0
输入端加译码器的可编程逻辑阵列比普通的可编程逻辑阵列具有更大的实现能力。这种阵列表现为三级或-与-或电路。本文提出了与该电路相关的一系列基本概念和理论,并且还进行了复杂性分析,结论是使用该阵列实现一个任意N变量逻辑函数所需的最大存储单元数为:(2n+1)2^n-2. 相似文献
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Peter Chapman Gem Stapleton Aidan Delaney 《Journal of Visual Languages and Computing》2013,24(5):327-349
Existing diagrammatic notations based on Euler diagrams are mostly limited in expressiveness to monadic first-order logic with an order predicate. The most expressive monadic diagrammatic notation is known as spider diagrams of order. A primary contribution of this paper is to develop and formalise a second-order diagrammatic logic, called second-order spider diagrams, extending spider diagrams of order. A motivation for this lies in the limited expressiveness of first-order logics. They are incapable of defining a variety of common properties, like ‘is even’, which are second-order definable. We show that second-order spider diagrams are at least as expressive as monadic second-order logic. This result is proved by giving a method for constructing a second-order spider diagram for any regular expression. Since monadic second-order logic sentences and regular expressions are equivalent in expressive power, this shows second-order spider diagrams can express any sentence of monadic second-order logic. 相似文献
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探讨了如何将数据结构中广义表进行扩展 ,并利用这个扩展广义表来设计逻辑表达式在计算机上的逻辑结构和存储结构 ,以及在这种结构上如何实现逻辑表达式的基本运算 ,进而实现其它复杂的表达式自动推导 相似文献
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Nguen Tkhi Min Vu G. S. Plesnevich 《Journal of Computer and Systems Sciences International》2016,55(6):912-923
This paper introduces Allen’s extended interval logic whose sentences are Boolean combinations of sentences of Allen’s interval logic with metric constraints on time points. For this extended logic, a deduction method based on analytic tableaux is defined. This method is used for answering queries on ontologies specified in Allen’s extended interval logic. An example illustrating the applicability of this extended logic to the problem of workflow specification is presented. 相似文献
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《Computers & Geosciences》2006,32(9):1368-1377
SQL is the (more or less) standardised language that is used by the majority of commercial database management systems. However, it is seriously flawed, as has been documented in detail by Date, Darwen, Pascal, and others. One of the most serious problems with SQL is the way it handles missing data. It uses a special value ‘NULL’ to represent data items whose value is not known. This can have a variety of meanings in different circumstances (such as ‘inapplicable’ or ‘unknown’). The SQL language also allows an ‘unknown’ truth value in logical expressions. The resulting incomplete three-valued logic leads to inconsistencies in data handling within relational database management systems. Relational database theorists advocate that a strict two-valued logic (true/false) be used instead, with prohibition of the use of NULL, and justify this stance by assertion that it is a true representation of the ‘real world’. Nevertheless, in real geoscience data there is a complete gradation between exact values and missing data: for example, geochemical analyses are inexact (and the uncertainty should be recorded); the precision of numeric or textual data may also be expressed qualitatively by terms such as ‘approximately’ or ‘possibly’. Furthermore, some data are by their nature incomplete: for example, where samples could not be collected or measurements could not be taken because of inaccessibility.It is proposed in this paper that the best way to handle such data sets is to replace the closed-world assumption and its concomitant strict two-valued logic, upon which the present relational database model is based, by the open-world assumption which allows for other logical values in addition to the extremes of ‘true’ and ‘false’. Possible frameworks for such a system are explored, and could use Codd's ‘marks’, Darwen's approach (recording the status of information known about each data item), or other approaches such as fuzzy logic. 相似文献
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文中 ,在密码系统状态间的关联性和时序逻辑的可达性间建立联系 ,探讨了一种基于时序逻辑的密钥分配协议的描述办法 .该途径从形式上规定密码设备的构成成分以及有关的密码操作 ,使用了时序逻辑的常量和状态不变量来表达这些构成成分 .有关的密码操作表达为状态转换 ,加密协议应保留的必要特性表达为临界不变性表达式 ,然后验证这些不变性表达式 .本方法的优点在于可以隐式地刻画攻击者的行为 ,具有形式化程度高等特点 .我们希望能为研究规范化、简洁化的形式化分析工具提供一些借鉴 . 相似文献
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本体描述知识的逻辑基础是描述逻辑(DL),虽然现有DL中对概念的描述方式非常丰富,但是角色却只能是原子角色。针对角色描述能力低的问题,在现有的DLSHIQ中增加了角色表达式来对角色进行描述,证明了如果知识库中所有角色表达式都是安全的,该知识库在现有的推理机KAON2上的推理仍然是Exp-Time,提出了一种判断角色表达式是否安全的算法。 相似文献
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Action systems have been shown to be applicable for modelling and constructing systems in both discrete and hybrid domains. We present a novel semantics for action systems using a sampling logic that facilitates reasoning about the truly concurrent behaviour between an action system and its environment. By reasoning over the apparent states, the sampling logic allows one to determine whether a state predicate is definitely or possibly true over an interval. We present a semantics for action systems that allows the time taken to sample inputs and evaluate expressions (and hence guards) into account. We develop a temporal logic based on the sampling logic that facilitates formalisation of safety, progress, timing and transient properties. Then, we incorporate this logic to the method of enforced properties, which facilitates stepwise refinement of action systems. 相似文献
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以安全重构元为基础,能够提供高灵活性、适应性和可扩展性安全服务的可重构安全计算系统已成为当前安全研究领域的热点问题.目前,关于重构机理的研究主要采取基于功能候选集的静态重构配置生成方法,可重构安全系统作为一种主动安全防御手段,应具有动态自动重构的能力,避免人工介入导致的脆弱性.针对动态自动可重构安全系统的建模以及配置生成过程的描述问题,提出了一种基于直觉主义逻辑扩展的动态自动可重构安全系统逻辑模型SSPE,给出了逻辑模型SSPE上的语法和推理规则,设计了基于SSPE的等级化安全重构元和安全需求建模和表达方法,并给出了基于映射关系的安全重构元描述向逻辑语言的转换规则.最后,以IPSec协议为例,阐述了可重构安全系统重构配置的动态自动推理生成过程.基于直觉主义逻辑的可重构安全系统建模和配置生成方法,为研究可重构安全系统的重构机理提供了新的思路和方法,具有重要的意义. 相似文献