产品形态设计的思考

产品形态设计怎样才能顺应时代的发展？根据我国国情,从国际流行趋势、功能、性能优化、人本性、新技术以及产品周期六个方面进行了探讨。     

Valuations,regular expressions,and fractal geometry

Valuations — morphisms from ( _n ^* ,·,) to ((0, ), ·, 1) — are a simple generalization of so-called Bernoulli morphisms. In this paper, we show a characterization of strongly unambiguous regular expressions with the help of valuations and formal power series. We apply these algebraic results to the determination of Hausdorff dimensions of fractals described by regular expressions.     

GOST 34.10—A brief overview of Russia's DSA

GOST 34.10 is Russia's DSA. Like its US counterpart, GOST is an ElGamal-like signature scheme used in Schnorr mode. It is similar to NIST DSA in many aspects. In this paper we will overview GOST 34.10 and discuss the three main differences between the two algorithms, (i) GOST's principal design criterion does not seem to be computational efficiency: the algorithm is 1.6 times slower than the DSA and produces 512-bit signatures. This is mainly due to the usage of the modulus q which is at least 254 bits long. During verification, modular inverses are computed by exponentiation (while the Extended Euclidian algorithm is roughly 100 times faster for this parameter size) and the generation of the public parameters is much more complicated than in the DSA. This choice of the parameters makes GOST 34.10 very secure. (ii) GOST signers do not have to generate modular inverses as the basic signature equation is s = xr + mk (mod q) instead of (mod q). (iii) GOST's hash function (the Russian equivalent of the SHA) is the standard GOST 34.11 which uses the block cipher GOST 28147 (partially classified) as a building block. The hash function will be briefly described. Copyright     

密码技术在当前信息安全领域中的应用研究

密码技术在信息安全中有着举足轻重的作用。文章介绍了密码技术的相关理论及应用现状,并以应用比较广泛的单向散列函数MD5为例介绍了单向散列函数在当前的应用,特别以网页设计中用户认证为例,对单向散列函数MD5所起的作用进行了比较。     

非线性系统的多模型DMC解耦设计

针对工业生产过程大多为多输入多输出非线性系统,干扰因素多,耦合作用强,常规控制方法难以获得满意控制效果的特.提出一种基于动态矩阵控制(DMC)的多模型控制方法,采用误差指标切换函数作为切换准则,根据其最小值来选择与实际最接近模型,并将基于此模型的控制器切换为当前控制器.结合目标函数解耦方法,在模型中考虑其他通道输入对当...     

公安现役院校大学计算机基础实践指导教材研究

在公安现役院校计算机基础教学改革中,大学计算机基础实践教学的课堂教学与实践教学分离,实践教学以学员自主学习为主。作为学员学习的主要参考资料和教学的有益补充,教材在新教学模式下的重要性越发突出。本文对公安现役院校大学计算机基础实践指导教材的建设思路和教材特色进行了详细阐述。     

Hash查找算法在液晶屏汉化系统中的应用

利用单片机实现了对某引进的火灾监控报警系统液晶显示模块的汉化工作。系统中对显示信息建立相应的单词字典,进行逐词翻译。在翻译过程中,采用快速的Hash查找算法来进行查找翻译,构造了一个计算简单的哈希函数并设定了一种简单有效的处理冲突的方法,有效地缩短了翻译时间,满足了汉化系统实时性的要求。     

Image City sharing platform and its typical applications

In this paper,the trend of urban spatial information sharing service from the electronic map to image is analyzed and its sharing framework based on service-oriented architecture is designed.Moreover,the service implementation,feedback data service procedure and its processing service model are explored. Based on the software with independent intellectual property rights,image city of Taizhou is developed as an example to realize various image data and processing servicesLastly,the bright future prospects o...     

数字图像LSB隐写分析统计模型初探

数字图像LS(BLeast Significant Bits)在统计上与二项分布相似,结构上与原宿主图像仍然具有一定的相关性,从而导致经典LSB替换算法产生直方图"阶梯效应"。本文主要从图像像素以及像素间关系的特征函数出发,观察其常见统计模型的变化,为设计有效的图像隐写算法及隐写分析算法提供参考依据。     

Global optimization of tool path for five-axis flank milling with a conical cutter

In this paper, optimum positioning of the conical cutter for five-axis flank milling of slender surfaces is addressed from the perspective of approximating the tool envelope surface to the data points on the design surface following the minimum zone criterion recommended by ANSI and ISO standards for tolerance evaluation. Based on the observation that a conical surface can be treated as a canal surface, i.e. envelope surface of one-parameter family of spheres, the swept envelope of a conical cutter is represented as a sphere-swept surface. Then, an approach is presented to efficiently compute the signed distance between a point in space and the swept surface without constructing the swept surface itself. The first order differential increment of the signed point-to-surface distance with respect to the differential deformation of the tool axis trajectory surface is derived. By using the distance function, tool path optimizations for semi-finish and finish millings are formulated as two constrained optimization problems in a unified framework, and a sequential approximation algorithm along with a hierarchical algorithmic structure is developed for the optimization. Numerical examples are given to confirm the validity and efficiency of the proposed approach. Comparing with the existing approaches, the present one improves the machining accuracy greatly. The rationale developed applies to general rotary cutters.