自动络筒机空气捻接器的机构分析与设计

利用机构分析和设计方法分析纱线捻接的机构运动,对捻接过程中纱线的抓取和导引机构进行运动剖析,以便设计该导纱空间机构及有关的凸轮廓线,为空气捻接器机构的设计改进提供理论基础.     

Simulation and Experimental Study of Dynamic Characteristics of a Pneumatic Actuator in Air Splicer

Splicing process parameters determined by dynamic characteristic of pneumatic actuator in air splicer have a significant influence on the performance of spliced yarn. Both gas thermodynamic and pneumatic actuator dynamic models, which were solved by the Runge-Kutta algorithm, were established to analyze the relationship among structural parameters of a pneumatic actuator and splicing process parameters such as splicing duration and gas consumption. Additionally,a visualization test bench to observe the dynamics of the pneumatic actuator and a mass flow measurement system to track splicing duration and gas consumption were designed. Comparisons between experimental data and simulation results show that the mathematical model accurately accounts for the dynamic characteristics of the pneumatic actuator,and consequently predicts splicing process parameters, which provides a theoretical foundation for the design optimization of air splicer.     

Tensile property of Pneumatic spliced Short-staple Ring Spun Yarns

The tensile property of the spliced yarn splice under different splicing conditions has been investigated. The retained spliced strength of the splice spliced under different splicing conditions was obtained as the indicator for the performance of the splicer under that particular splicing condition. The results showed that, the length of the yarn tails and the yarn linear density are the parameters that has the most important effect to the tensile property of the spliced yarn.     

自动络筒机空气捻接器的捻接原理研究

研究自动络筒机空气捻接器的捻接原理.对退捻后纱线尾端的曲线函数进行研究,指出了一种合理的纱线尾端的曲线函数,并利用流体力学原理,具体描述了纱线在捻接孔内的运动,揭示了纱线捻接原理.     

光子晶体光纤熔接热源偏移量的研究

在光子晶体光纤的熔接过程中,由于包层空气孔大小及结构的不同,使得熔接时热源的功率和位置均不同,使得加热过程更为复杂.本文在对待熔的光子晶体光纤的热传导特性研究基础上,通过三维热传导仿真研究光子晶体光纤熔接过程中的最佳偏移量.通过仿真分析和实验研究表明:本文提出的方法可以用于计算光子晶体光纤的最佳熔接条件,从而完成光子晶体光纤与传统单模光纤间的低损耗熔接.     

Comprehensive proteomic analysis of the human spliceosome

The precise excision of introns from pre-messenger RNA is performed by the spliceosome, a macromolecular machine containing five small nuclear RNAs and numerous proteins. Much has been learned about the protein components of the spliceosome from analysis of individual purified small nuclear ribonucleoproteins and salt-stable spliceosome 'core' particles. However, the complete set of proteins that constitutes intact functional spliceosomes has yet to be identified. Here we use maltose-binding protein affinity chromatography to isolate spliceosomes in highly purified and functional form. Using nanoscale microcapillary liquid chromatography tandem mass spectrometry, we identify approximately 145 distinct spliceosomal proteins, making the spliceosome the most complex cellular machine so far characterized. Our spliceosomes comprise all previously known splicing factors and 58 newly identified components. The spliceosome contains at least 30 proteins with known or putative roles in gene expression steps other than splicing. This complexity may be required not only for splicing multi-intronic metazoan pre-messenger RNAs, but also for mediating the extensive coupling between splicing and other steps in gene expression.     

基于小区域融合的实时视频拼接技术

针对视频拼接实时性的需求, 提出一种利用小区域融合和查表映射实现实时视频拼接的方法. 该方法首先利用颜色校正算法对待拼接摄像头视频进行颜色校正; 然后在初始化阶段估算出图像变换参数和小区域融合权值, 并以索引表的方式保存; 最后在视频拼接阶段利用查表法对视频进行实时拼接. 实验结果表明, 该方法在较好消除残影和拼接缝隙的同时, 能将每帧的平均拼接时间降低至约0.03 s, 并在拼接速度和拼接效果上都较好.     

Alternative pre-mRNA splicing and proteome expansion in metazoans

The protein coding sequences of most eukaryotic messenger RNA precursors (pre-mRNAs) are interrupted by non-coding sequences called introns. Pre-mRNA splicing is the process by which introns are removed and the protein coding elements assembled into mature mRNAs. Alternative pre-mRNA splicing selectively joins different protein coding elements to form mRNAs that encode proteins with distinct functions, and is therefore an important source of protein diversity. The elaboration of this mechanism may have had a significant role in the expansion of metazoan proteomes during evolution.     

A mutant immunoglobulin light chain is formed by aberrant DNA- and RNA-splicing events

A mutant immunoglobulin gene has been formed by an abnormal (non V/J) recombination event such that abnormal RNA splicing is required to form a mutant light chain. The structure of the gene suggests that the small palindrome thought to be involved in V/J joining also provides the basis for this abnormal DNA recombination and that the absence of a J segment and RNA splice signal allows an abnormal RNA splicing reaction to occur.     

A suppressor of a yeast splicing mutation (prp8-1) encodes a putative ATP-dependent RNA helicase

Five small nuclear RNAs (snRNAs) are required for nuclear pre-messenger RNA splicing: U1, U2, U4, U5 and U6. The yeast U1 and U2 snRNAs base-pair to the 5' splice site and branch-point sequences of introns respectively. The role of the U5 and U4/U6 small nuclear ribonucleoprotein particles (snRNPs) in splicing is not clear, though a catalytic role for the U6 snRNA has been proposed. Less is known about yeast splicing factors, but the availability of genetic techniques in Saccharomyces cerevisiae has led to the identification of mutants deficient in nuclear pre-mRNA splicing (prp2-prp27). Several PRP genes have now been cloned and their protein products characterized. The PRP8 protein is a component of the U5 snRNP and associates with the U4/U6 snRNAs/snRNP to form a multi-snRNP particle believed to be important for spliceosome assembly. We have isolated extragenic suppressors of the prp8-1 mutation of S. cerevisiae and present here the preliminary characterization of one of these suppressors, spp81. The predicted amino-acid sequence of the SPP81 protein shows extensive similarity to a recently identified family of proteins thought to possess ATP-dependent RNA helicase activity. The possible role of this putative helicase in nuclear pre-mRNA splicing is discussed.     

基于游程长度和边缘统计的图像拼接检测

阐述了一种利用图像内在统计特性进行图像拼接检测的方法。图像拼接检测是一个基于拼接图像特征的模式识别问题。本文通过对游程长度和图像边缘的统计特性进行分析,说明了拼接操作所引起的图像像素不相关性和不连续性。为进行拼接检测,从图像游程长度和图像边缘统计特性中提取特征量,以此特征量去训练神经网络作为最后的分类器。结果表明,由此特征量作为图像拼接检测的标准,检测结果的精确度良好。     

隐Markov模型在剪接位点识别中的应用

剪接位点的识别是基因识别中的一个重要环节。由于现有的基因识别算法主要关注编码区的整体特性 ,而并不着重考虑个别位点的信息 ,因此难以准确地识别出剪接位点。考虑到剪接位点附近的保守序列的相邻碱基之间应该存在某种相关性 ,利用一阶 Markov链建立了表述这种相关性的模型 ,在此基础之上 ,设计了专门用于剪接拉点识别的隐马氏模型 (HMM)方法。实验结果表明 ,用 HMM描述剪接位点附近序列符合实际情况 ,并且利用这一方法进行剪接位点的识别可以很好地提取位点附近保守序列在边缘分布与条件分布 (转移概率 )上的统计特征。使用该方法对真实剪接位点和虚假剪接位点进行识别 ,识别率均可达 90 %以上。     

气垫式胶带输送机气膜的形成及其影响因素

气垫式胶带输送机的技术关键是形成一层均匀稳定性的气膜。本文根据多年来的研究成果，分析气膜形成的机理及其影响因素，介绍各因素的相互关系和各参数的合理选择。     

A role for branchpoints in splicing in vivo

The nucleotides immediately surrounding intron/exon junctions of genes transcribed by RNA polymerase B can be derived from 'consensus' sequences for donor and acceptor splice sites by only a few base changes. Studies in vivo have underlined the importance of these junction nucleotides for splicing. In higher eukaryotes, no evidence has been found for specific internal intron sequences involved in splicing. However, the recent discovery that, in vitro, introns are excised in a lariat form where the 5' end of the intron is joined via a 2'-5'-phosphodiester linkage to an A residue (branchpoint acceptor) close to the 3' end of the intron, suggests that internal intron sequences may nonetheless be important for splicing. Indeed, in yeast nuclear genes, the internal sequence 5'-TACTAAC-3' (or close homologue) is essential for splicing in vivo. A proposed consensus sequence for branchpoints in mammalian introns is 5'-CT(A/G)A(C/T)-3'. This sequence resembles the essential yeast internal sequence. Are branchpoints involved in the splicing of introns of higher eukaryotes in vivo? We show here that a branchpoint sequence from a human globin gene (5'-CTGACTCTCTCTG-3') greatly enhances the efficiency of splicing of a 'synthetic' intron in HeLa cells. A mutated branchpoint sequence, 5'-CTCCTCTCTCTG-3', in which the branchpoint acceptor nucleotide A has been deleted and the neighbouring purine G mutated to a C, does not exhibit this enhancing capability. We conclude that branchpoints have an important function in the splicing process in vivo.     

装药位置对坑道中冲击波传播规律的影响

为了弄清装药位置及形状对坑道中冲击波传播规律的影响,基于Hopkinson比例定律,用LS—DYNA动力有限元软件较为系统地研究了不同装药位置和装药形状情况下,坑道中冲击波峰值压力的传播规律,计算结果与其他经验方法的预测结果进行了比较．研究表明,在爆炸近区,装药位置及形状对预测结果均有明显影响;随着传播距离的增加,装药位置的影响越来越小,而装药形状的影响却变得突出．研究结果可供类似问题的研究及防护门的设计参考．     

电影院空调系统的设计

结合对某电影城空调方案的设计 ,分析了电影院空调负荷的特点及最佳的气流组织形式 ,指出电影院空调设计中除了要考虑观众的舒适性之外 ,还要兼顾风管、设备等对影院的视听效果的影响 ,室内环境也是关系影院经济效益的重要因素     

羽状流作用下的非等温空调射流运动研究

在传统非等温射流理论的基础上,考虑由室内热源形成的羽状气流对非等温空调射流的热浮升作用,建立数学模型,得到了在内热源作用下非等温射流运动轨迹方程表达式。同时对不同热源形式、热源大小以及热源位置对空调射流和室内热舒适性的影响进行了实验研究,并根据实验结果对热源与射流的相互作用进行了讨论。结果表明,室内热源的存在将明显改变空调射流的运动轨迹,影响室内热舒适性。