How We Broke the Union Code (148 Years Too Late)

Abstract

We decrypt a hitherto undeciphered Union message from the United States Civil War. Our means of cryptanalysis of the (Stager) cipher combines an appreciation of the limitations of human-generated randomness and several applications of the principle known as Ockham's Razor. We work without any codebooks and, in the process of our analysis, identify and explain the error that was made in the encryption of this letter from Porter to McClellan (about 148 years ago) that likely led to it being undecipherable—until now.     

优化生产工艺提高x800腈纶膨体条缩率

文章在借鉴以往生产经验的基础上,利用统计分析与正交试验相结合的方法,对德国拜耳公司x800丝束生产腈纶膨体条提高缩率的制条工艺进行优化选择,既满足顾客20%缩率的要求,又提高了企业的生产效益.     

易染型海岛PTT纤维的碱处理研究

研究了易染型海岛PTT纤维的碱处理工艺条件,即达到最佳碱处理效果的碱浓度、碱处理时间和碱处理温度以及双烷基二甲基氯化铵(812)的浓度。结果表明最佳工艺条件为:NaOH质量分数12%,浴比1∶50,碱处理温度90℃,时间60 min。加入协同剂能明显提高纤维的碱减量率,协同剂的最佳质量分数为0.7%。     

65Mn软态异型钢丝断裂分析及工艺改进

分析了软态异型钢丝断裂原因，介绍了改进的生产工艺及效果。     

The Workpiece Material in Machining

In machining operations, much attention is paid to the improvement of the lifetime of tools by increasing the hardness of the tool whether or not it is combined with an optimised hard coating. Another method is to change the geometry of the tool by chip breakers and thus shorten the contact time and decrease the friction between chip and tool. Up to now, little attention has been paid to gaining an understanding of the influence of the workpiece material in machining. From forming operations, it is known that the fracture strain under different stress conditions can be predicted by using ductility curves. These curves can be determined easily by two simple material tests. It will be shown that these curves can also be used to understand chip breaking. The work clarifies a part of the role of the cooling liquid, and also the phenomenon that the tool life can sometimes be increased by using a harder workpiece material. A lower friction between chip and tool can be more effective than a harder tool material. Application of this idea teaches us the effect of Molybdenum sulphide (MoS2 ) as a tool coating and the fine cutting of steel with diamond tools. Another workpiece material property that influences the life-time of tools is its strain rate dependency on the flow stress. Its prediction is not easy and strongly depends on the material.     

引起中低压电网电压异常的故障分析与辨识

在中低压电网中，PT断线、单相接地及由PT饱和引起的铁磁谐振均是多发性的故障，这些故障都能使电压异常。PT一次不对称断线和单相接地时，电压互感器开口三角形都有电压，绝缘监查装置都会发接地信号，不能根据所发信号区分是单相接地还是PT断线。单相接地和铁磁谐振往往均表现为中性点出现位移电压，尤其是基波谐振更不易与单相接地区分。此文在分析各种故障特征的基础上，提出了当电压异常时辨识故障的方法，能有效判断是出现何种故障。     

义县下生木营子——车坊压性断裂地下水赋存特征

本文从地质构造、岩性特征、地下水赋存条件和分布规律等方面,较详细的论述了下生本营子——车坊断裂地下水赋存特征,同时指出压性断裂影响岩带是地下水富集的最有利部位。     

Extrusion deactivation of rice bran enzymes by pH modification

Rice bran is considered in Mexico as “waste”, useful only for feeds. As considerable amounts of oil are available in rice bran, it might be worthwhile to stabilize it and extract the edible oil before using it for feedstuffs. Precisely these oils are responsible for rice bran rapid deterioration, particularly in climatic conditions such as those prevalent in Mexico's tropical areas (high humidity and high temperature). This paper deals with the study of the effect of pH during extrusion of fresh rice bran in order to inactivate lipid‐breaking enzymes. Hydrochloric acid or calcium hydroxide, Ca(OH)₂, were added at 0, 1, 5, 10% (dry basis), and moisture content of the bran samples was varied (20, 30, 40%, dry basis) in a 3² factorial design to corroborate its effect at acid and alkaline pH range. Free fatty acids (FFA) increase was the control variable. Extruded samples were stored at room temperature (between 20 and 28 °C) using a non‐extruded sample as control to assess the shelf life effects. Results indicate that in acid‐extruded samples, the increase in FFA concentration after 98 days was much less than in the unmodified‐pH or alkaline samples. The lowest FFA increase after 3 months of storage time was <10 mg FFA/g rice bran using extrusion with no water or chemicals added or using extrusion adding HCl, irrespective of the moisture content of rice bran.     

采煤机破碎机行星机构轴承固定螺栓断裂分析

通过对采煤机破碎机行星机构轴承固定螺栓断口面进行分析,并结合相应螺栓的使用环境、受力情况及工作状况,分析和探讨其断裂的原因,同时提出了相应的改进措施,从而提高破碎机的承载能力,延长破碎机工作寿命,保证设备稳定运转,减少维修次数,降低维修成本。     

重型矿用汽车制动过程动态模拟

重型矿用汽车制动过程是工况复杂的多种因素综合作用的过程．具有不确定性和很差的重复性．利用计算机模拟技术研究汽车制动过程，为新型矿用汽车制动系统设计、预测和评价提供了十分有效的手段．