Solid Modeling Error : Analysis and Compensation

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TSP问题的脂肪计算复杂性与启发式算法设计

旅行商问题(traveling salesman problem,简称TSP)是经典的NP-难解组合优化问题之一,求解它的高效启发式算法一直是计算机科学研究的热点.脂肪作为描述TSP结构特征的新工具,对启发式算法设计具有重要意义.目前,TSP问题的脂肪研究还处于初始阶段,缺乏理论分析结果及相关的启发式算法.首先分析了TSP问题的脂肪计算复杂性,通过构造偏移实例的技巧,证明了获取TSP的脂肪是NP-难解的,即在P(NP的假设下,不存在算法可以在多项式时间内获得完整脂肪.在此基础上,通过分析TSP问题局部最优解与脂肪的关系,给出了求解TSP问题的元启发式算法--动态候选集搜索(dynamic candidate set search,简称DCSS)算法.利用该算法,改进了目前求解TSP问题最好算法之一的LKH.TSPLIB典型实例的实验结果表明,改进后的算法在解的质量上有较为明显的提高.新的基于脂肪的启发式算法对于求解其他NP-难解问题具有一定的参考价值.     

复合杂粕多菌种发酵工艺研究

以枯草芽孢杆菌、黑曲霉和酿酒酵母为出发菌株,通过对固态发酵工艺条件的优化,获得复合菌种固态发酵生产蛋白质饲料的最佳工艺参数。结果表明:以棉籽粕45%、菜籽粕15%、玉米酒精糟15%、麸皮21%和硫酸铵2%为发酵基质,枯草芽孢杆菌∶酿酒酵母∶黑曲霉为2∶1∶1、接种量12%、发酵基质初始含水率45%、发酵温度34℃和发酵时间60h为发酵条件,发酵后粗蛋白质达42.5%,比发酵前提高15.5%;游离棉酚从1 240mg/kg降至360mg/kg,脱毒率达71%;粗纤维含量下降。     

金属基复合材料连接方法研究综述

拥有良好综合性能的金属基复合材料的应用往往受到没有成熟连接方法的限制。为解决这个问题, 本文对各种连接金属基复合材料的方法进行了系统阐述,并分析其各自的应用场合和限制条件,以便读者进行复合材料连接工艺选择时参考。     

微机电引信发展模式探讨

引信是一个相当复杂的机电系统,ＭＥＭＳ技术对未来引信的发展将带来哪些影响是一个值得认真探讨的问题,针对引信的信息,结构特点,应用ＭＥＭＳ技术,微机电引信的发展可能在三个层次上改变未来引信的面貌;（１）部件级,可制作固态安全系统;（２）产品级,导致固态引信的发展,（３）系统级,实现制导－引信一体化。     

采收期对“鄂选2号”山桐子果实成分及脂肪酸组成变化影响

为探寻木本油料山桐子果实及种子中油脂的积累动态规律,对不同采收期的预选品种“鄂选2号”的山桐子果实的整果、果肉和种子中的基本化学成分含量进行比较,并运用气相色谱-质谱联用对不同部位的油脂中的脂肪酸组成进行测定。结果表明,“鄂选2号”山桐子油料最佳采收期为盛花期后128 d左右,此时山桐子全果平均含油率为40.25%,果肉中的平均含油率为44.60%,种子中的平均含油率为30.55%。果实各部位的主要脂肪酸组成主要为肉豆蔻酸(C14∶0)、棕榈酸(C16∶0)、棕榈油酸(C16∶1)、珍珠酸(C17:0)、硬脂酸(C18∶0)、油酸(C18∶1)、亚油酸(C18∶2)、γ亚麻酸(C18∶3n6)、花生酸(C20∶0)、山嵛酸(C22∶0),其中种子油脂中亚油酸质量分数高于整果和果实,高达61.43%。     

全固态氨气传感器

概括了目前氨气传感器的国内外发展状况，提出了传统电化学气体传感器存在的问题，介绍了一种利用Nafion膜为固态电解质的氨气传感器，阐述了它的工作原理，对电极材料、薄膜材料、固态电解液、电路等关键技术进行了讨论，重点介绍了电极的活化、液态电解质的固化及传感器的抗干扰、抗恶劣环境影响等技术研究，给出了传感器的结构和电路原理图，讨论了传感器的性能特点和发展方向。     

The passage of homopolymeric RNA through small solid-state nanopores

Solid-state nanopores are widely acknowledged as tools with which to study local structure in biological molecules. Individual molecules are forced through a nanopore, causing a characteristic change in an ionic current that depends on the molecules' local diameter and charge distribution. Here, the translocation measurements of long (~5-30 kilobases) single-stranded poly(U) and poly(A) molecules through nanopores ranging from 1.5 to 8 nm in diameter are presented. Individual molecules are found to be able to cause multiple levels of conductance blockade upon traversing the pore. By analyzing these conductance blockades and their relative incidence as a function of nanopore diameter, it is concluded that the smallest conductance blockades likely correspond to molecules that translocate through the pore in predominantly head-to-tail fashion. The larger conductance blockades are likely caused by molecules that arrive at the nanopore entrance with many strands simultaneously. These measurements constitute the first demonstration that single-stranded RNA can be captured in solid-state nanopores that are smaller than the diameter of double-stranded RNA. These results further the understanding of the conductance blockades caused by nucleic acids in solid-state nanopores, relevant for future applications, such as the direct determination of RNA secondary structure.     

用厚透镜实现分数阶付里叶变换

本文给出了厚透镜实现分数阶付里变换的光学结构；定量分析了阊最透镜和双厚秀镜结构中分数付里叶变换和透镜参数之间的关系。计算表明用厚透镜可以实现分类阶付时变换。     

Effects of fiber orientation angles of fiber-reinforced plastic on sand solid particle erosion behaviors

Solid particle erosion in industrial applications has been a serious problem in many engineering fields. Earlier studies on fiber-reinforced plastic (FRP) composites were mainly focusing on the erosive wear behavior at several different impact angles. However, the effect of fiber orientation on FRP composites has not been thoroughly investigated. Since fiber orientation is one of the important factors in which causing erosive wear damages to FRP composites, in order to understand the virtue of this problem, it is important to investigate the effect of fiber orientation at different impact angles. In this research, the effect of fiber orientation of unidirectional fiber-reinforced plastic composites on erosive wear behavior was studied. Sandblasting-type erosion tests were conducted on the FRP composites with fiber orientation ranging at three impact angles to clarify the relation between fiber orientation and erosive wear behavior. The Dyneema fiber (ductile material) and the carbon fiber (brittle material) were used for the reinforcement fiber in FRP. From the result, it is confirmed that CFRP composites with higher fiber orientation angle erode faster than the composites with lower fiber orientation angle. But the erosion characteristic of DFRP was almost the same regardless of the fiber orientation angle. The damaged surfaces of the FRP composites were then analyzed using scanning electron microscopy and the possible erosion wear mechanisms were investigated.