THE TWO-MESSAGE PROBLEM IN CIPHER TEXT AUTOKEY. PART II

This is Part II of a two-part paper on the problem of the title. In this part the analysis of the two-message problem started in Part I is completed. In addition a brief discussion is given of a computer-assisted solution. A list of twelve two-message problems involving several types of conditions is attached for the benefit of the reader.     

A tree-structured crash surrogate measure for freeways

In this paper, we propose a novel methodology to define and estimate a surrogate measure. By imposing a hypothetical disturbance to the leading vehicle, the following vehicle’s action is represented as a probabilistic causal model. After that, a tree is built to describe the eight possible conflict types under the model. The surrogate measure, named Aggregated Crash Index (ACI), is thus proposed to measure the crash risk. This index reflects the accommodability of freeway traffic state to a traffic disturbance. We further apply this measure to evaluate the crash risks in a freeway section of Pacific Motorway, Australia. The results show that the proposed indicator outperforms the three traditional crash surrogate measures (i.e., Time to Collision, Proportion of Stopping Distance, and Crash Potential Index) in representing rear-end crash risks. The applications of this measure are also discussed.     

A Mixture Toxicity Study Employing Binary Combinations Of Dinitrobenzene And Trinitrobenzene Using The Bioluminescent Marine Bacterium Vibrio Harveyi As The Test Organism

A combination mixture study was conducted with two organic compounds, dinitrobenzene and trinitrobenzene, using the marine bioluminescent bacterium Vibrio harveyi . This assay employs the photogenic properties of this organism for determination of toxicity in a direct procedure. Evaluation of toxicity was performed using an additive index methodology, mixture toxicity index and graphic representations. Graphic representations employed were isobole plot and isobologram, both isopleths. The additive index procedure employed both chemicals at their estimated median effective concentration (EC 50 ) for determination of a toxicity value. Isopleths employed combinations of both chemicals, using an equitoxic concentration, at 20% intervals of their EC 50 . An additive index value for this mixture was statistically antagonistic. Mixture toxicity index suggests that these chemical in various combinations are antagonistic. Combinations for both isopleths were similar and exhibited additivity for three mixture values and statistical synergism for one mixture. Statistical analysis of combinations using the z test found some mixtures to be statistically different. This analysis, in part, supports findings for isopleths. These results suggest that different mixtures of the two chemicals may have different interaction outcomes.     

华东热湿地区四种植物群落类型对降温效应的影响研究

中国城市化进程不断推进,城市热岛效应的强度和负面影响越来越大,因此研究绿地植物群落类型对城市降温效应的影响具有重要意义。在实地调研的基础上,采用多元统计和拟合函数模型等方法,利用叶面积指数、三维绿量等因子分析4种植物群落类型的降温效应,以揭示绿地植物群落类型对降温效应影响的内在机制。夏季,4种植物群落类型对降温效应影响趋势分布排序为:乔木—灌木—草坪群落群植小乔木群落乔木—草坪群落乔木—硬质铺装群落;其中乔木—草坪群落与乔木—硬质铺装群落的降温效应较为接近。将反映植物群落特征的因子导入拟合数学方程模型,从而形成对降温效应作用较好的群落结构。研究结果和研究创新之处在于研究结果阐述了绿地植物群落类型对降温效应影响的内在作用机制。     

浅析金属非金属矿山安全评价指标体系与评价方法

金属非金属矿山每年死亡人数仅次于道路交通和煤矿事故，重大事故发生率高，危害大，安全形势相当严峻，而且金属非金属矿山安全预警体系的研究目前在国内仍属空白。通过对矿山事故调查、金属非金属矿山井下安全系统的组成特征及工艺流程分析，结合系统安全工程学原理，提出了初步的金属非金属矿山安全评价指标体系与评价方法。     

向32 nm迈进的光刻技术

概述了用于45nm节点的各种光刻技术发展现状及技术路线,结合国际半导体技术发展指南(ITRS)和各公司最新宣布的研究成果,探讨了各种光刻技术用于32nm节点的可能性。     

一般非线性系统的相关阶与线性化

讨论了一般非线性控制系统的线性化问题．基于一般非线性系统相关阶的概念,以微分几何方法为工具,给出一般非线性系统可线性化的一个充要条件,分析了相关阶、特征函数和系统维数的关系,并严格证明了线性化判据的必要性．     

变化环境下鄱阳湖洪水指标演变特征研究

本文基于鄱阳湖洪水特点,选取特定洪水特征指标,利用数理统计方法分析鄱阳湖洪水特征指标的趋势性、突变性和周期性,并分析演变特征和驱动因素,得到结论如下：1）未来高洪可能性仍然较大,未来6～10a鄱阳湖年最高水位仍处于丰水期;2）洪水在年内分配发生较大改变,变化过程从“矮胖型”向相对“尖瘦型”演变,水量在年内更加集中化;3）高洪持续天数显著增加,19.00m以上的高水位维持时间平均每10a延长2.2d;4）年最高水位及年平均水位周期性变化主要受“五河”入湖周期性变化所控制,同时会受到其他因素影响而改变原有周期性变化规律,年最高水位具有5a为第一主周期,40～49a为第二主周期的变化规律。     

193 nm浸液式光刻技术现状

概述了193nm浸液式光刻技术发展现状及技术路线,结合国际半导体技术发展指南(ITRS)和各公司在SPIE微光刻研讨会上宣布的最新研究成果,探讨了193nm浸液式光刻技术的发展趋势。     

具有三级索引词库结构的中文分词方法研究

提出了一种分组并具有三级索引结构的词库组织体系,给出了合适的索引密度间隔;针对系统基本词库的扩充问题,考虑了一种基于词频统计并具有过滤功能的关键词自动抽取和小词条添加方法。大量仿真实验结果表明,采用该方法可较大提高中文文本的切词速度及信息的查全查准率。