给定节点数的开关电路拓扑推演

建立了一种以图论为基础的寻找新电路的拓扑推演方法 ,通过对开关状态的穷举和组合形成拓扑 ,并根据电路判据和可控性判据来判定拓扑的有效性。该方法具有系统化、机器化的特点 ,可以广泛地用于寻找软开关、功率因数校正等新型电力电子电路 ,还可以用于开关电容网络的研究。     

分割多边形成凸多边形的算法

提出将任意简单多边形分割成若干个凸多边形的一种算法，主要思想是：首先确定多边形的凹点，然后利用连接凹点与落入该点Ｂ域中顶点的方法，消去该凹点，从而分割原多边形成两个子多边形，最后对子多边形递归使用该方法，直至消去全部凹点该算法分割多边形成Ｏ（ｌ）个凸多边形，其时间复杂性是Ｏ（ｎ）次乘法，其中ｎ是多边形的顶点个数，ｌ为凹点数目     

混合实验法在W-Ni-Cu合金组分设计中的应用

采用极端顶点设计法设计W-Ni-Cu合金组分,将组分自变量与相对应的性能因变量(相对密度、显微硬度、抗弯强度)进行回归分析和规划求解,同时采用冷压烧结法制备不同组分的W-Ni-Cu合金,测定合金的密度、显微硬度和力学性能,研究组分对合金性能的影响。结果表明:回归方程复相关系数R~2=1,方程精确度高;合金性能随组分变化而呈规律变化;当Ni含量与Cu含量(均为质量分数)分别为3%和5%时,合金的综合力学性能最佳:相对密度为94.295%、显微硬度286.55、抗弯强度931.51 MPa。W-Ni-Cu合金的相对密度计算值与实验结果的误差为-0.45%~0.06%,显微硬度计算值与实验结果的误差为-8.48%~4.46%,抗弯强度计算值与实验结果的误差为-5.19%~4.15%。误差很小,说明混合实验和极端顶点设计法能优化W-Ni-Cu合金组分,并可靠预测合金性能。     

一种求解有向图最小反馈节点集的搜索算法

反馈节点集问题源于组合电路的设计,在预防计算机操作系统的死锁、VLSI芯片设计、计算机程序证明以及贝叶斯推论等方面部有极其重要的应用。最小反馈节点集问题是一个NP完全问题,很难准确求解。该文在计算流程、图的约减操作以及贪婪函数3个方面对以前求解该问题的贪婪随机适应性搜索算法作了改进。实验表明改进的算法无论在计算结果方面还是在计算稳定性方面都要优于前者,同时还在一定程度上减少了计算时间。     

区域性赤峪断层落差及延展方向分析

为深入研究赤峪断层在紫晟煤业的落差及延展方向,减少构造损失煤量。通过地表踏勘查看断层出露情况,井下钻探探测断层延展位置,补充施工地质勘探钻孔对比岩层缺失层位,判明了区域性赤峪断层在紫晟煤业东南部呈现为4条密集分布的断层组,断层组在2-107工作面外围约115m,断层破碎带宽约220m,总落差190~325m,由西南至东北部总落差逐步减小。     

A two-step cloning-free PCR-based method for the deletion of genes in the opportunistic pathogenic yeast Candida lusitaniae

We describe a new cloning-free strategy to delete genes in the opportunistic pathogenic yeast Candida lusitaniae. We first constructed two ura3 Δ strains in C. lusitaniae for their use in transformation experiments. One was deleted for the entire URA3 coding sequence; the other possessed a partial deletion within the coding region, which was used to determine the minimum amount of homology required for efficient homologous recombination by double crossing-over of a linear DNA fragment restoring URA3 expression. This amount was estimated to 200 bp on each side of the DNA fragment. These data constituted the basis of the development of a strategy to construct DNA cassettes for gene deletion by a cloning-free overlapping PCR method. Two cassettes were necessary in two successive transformation steps for the complete removal of a gene of interest. As an example, we report here the deletion of the LEU2 gene. The first cassette was constituted by the URA3 gene flanked by two large fragments (500 bp) homologous to the 5' and 3' non-coding regions of LEU2. After transformation of an ura3 Δ recipient strain and integration of the cassette at the LEU2 locus, the URA3 gene was removed by a second transformation round with a DNA cassette made by the fusion between the 5' and 3' non-coding regions of the LEU2 gene. The overall procedure takes less than 2 weeks and allows the creation of a clean null mutant that retains no foreign DNA sequence integrated in its genome.     

猪繁殖与呼吸综合征弱毒疫苗的安全性及新型疫苗的研究进展

猪繁殖与呼吸综合征(Porcine reproductive and respiratory syndrome,PRRS)是影响养猪业的重大传染病,应用PRRS弱毒疫苗免疫是主要的预防措施。尽管各种PRRS弱毒疫苗已在我国使用,但PRRS仍持续流行,每年均有不同程度的暴发,且造成巨大的经济损失。最新研究提示,基因缺失疫苗能有效提升猪对PRRS的特异性免疫力。本文就PRRS弱毒疫苗在使用过程中可能存在的安全隐患及新型疫苗的研究进展作一综述。     

三维网格模型数据流压缩算法研究

当前的网格压缩算法在编码顶点和连通信息之前,需要按照某种顺序遍历网格模型,而且需要构造支持拓扑结构访问的临时数据结构,不利于处理大型网格模型.从根源上抛弃了传统网格数据组织形式,给出了一种新的网格顶点和连通信息交错的网格数据组织方法,提出了以网格数据读入顺序渐进编码算法.实验结果表明,算法的处理速度和所占用的内存空间都优于传统的压缩方法.     

适用于曲线轮廓工件排样的顶点算法

优化排样中的多边形顶点算法是目前主流方法中应用较多的一种方法.顶点算法的核心是根据顶点和边的关系找出相对边和相切点,该方法在处理含有曲线轮廓的排样问题时,有一定的局限性.本文参考了排样碰撞算法中碰撞点的提取方法,将其用于完善排样顶点算法对圆弧轮廓的处理,即将相对边分为圆与直线相切,圆与圆相内切,圆与圆相外切三种情况处理.完善后的方法实际上是顶点算法和碰撞算法的结合,在一定程度上扩大了顶点算法的应用范围,提高了排样的精确性.     

A White Plaque,Associated with Genomic Deletion,Derived from M13KE-Based Peptide Library Is Enriched in a Target-Unrelated Manner during Phage Display Biopanning Due to Propagation Advantage

The nonspecific enrichment of target-unrelated peptides during biopanning remains a major drawback for phage display technology. The commercial Ph.D.^TM-7 phage display library is used extensively for peptide discovery. This library is based on the M13KE vector, which carries the lacZα sequence, leading to the formation of blue plaques on IPTG-X-gal agar plates. In the current study, we report the isolation of a fast-propagating white clone (displaying WSLGYTG peptide) identified through screening against a recombinant protein. Sanger sequencing demonstrated that white plaques are not contamination from environmental M13-like phages, but derive from the library itself. Whole genome sequencing revealed that the white color of the plaques results from a large 827-nucleotide genomic deletion. The phenotypic characterization of propagation capacity through plaque count- and NGS-based competitive propagation assay supported the higher propagation rate of Ph-WSLGYTG clone compared with the library. According to our data, white plaques are likely to arise endogenously in Ph.D. libraries due to mutations in the M13KE genome and should not always be viewed as exogenous contamination. Our findings also led to the conclusion that the deletion observed here might be an ancestral mutation already present in the naïve library, which causes target-unrelated nonspecific enrichment of white clone during biopanning due to propagation advantage.