基于改进局部切空间排列的流形学习算法

局部切空间排列是一种广受关注的流形学习算法,其具备实现简单、全局最优等特点,但其难以有效处理稀疏采样或非均匀分布的高维观测数据。针对这一问题,该文提出一种改进的局部切空间排列算法。首先,提出一种基于L1范数的局部切空间估计方法,由于同时考虑了距离和结构因素,该方法得到的切空间较主成分分析方法更为准确。其次,在坐标排列步骤为了减小排列误差,设计了一种基于流形结构的加权坐标排列方案,并给出了具体的求解方法。基于人造数据和真实数据的实验表明,该算法能够有效地处理稀疏和非均匀分布的流形数据。     

Nikon光刻机对准系统概述及模型分析

对准系统是光刻机中最精密复杂的部分,掌握对准原理是设计和使用光刻机的关键之一。阐述Nikon步进投影光刻机（Stepper）的对准机制,详细介绍目前应用于Nikon步进光刻机硅片对准的三种对准方式：LSA、FIA、LIA,比较它们的优缺点。并结合数学模型对影响Nikon对准模型信号强度进行分析,为提高对准精度提供了依据,对实际应用有一定的指导作用。     

在图像传感器和存储产品中应用硅通孔工艺的300 mm光刻与键合技术

三维集成的技术优势正在延伸到大量销售的诸如消费类电子设备潜在应用的产品领域。这些新技术也在推进着当前许多生产工艺的包封能力,其中包括光刻工艺和晶圆键合。〉还需要涂胶．形成图形和刻蚀图形结构。研究了一些用于三维封装的光刻和晶圆键合技术问题并将叙述全部的挑战和适用的解决方案。技术方面的处理结果将通过晶圆键合和光刻工序一起讨论。     

基于遗传算法与星比对的多序列比对混合算法

多序列比对(MSA)是一个典型的NP完全问题,星比对是一种有效的多序列比对算法。文章针对MSA问题提出了将遗传算法与星比对算法结合在一起的混合算法,该算法充分发挥了遗传算法和星比对算法的优越性,可提高求解MSA问题的计算精度和计算速度,整个算法模拟了自然界进化的周期性,较好的解决了群体的多样性和收敛深度的矛盾。实验表明,该算法是有效的。     

Community-based initiatives in the Dutch water domain: the challenge of double helix alignment

ABSTRACT

Community-based initiatives (CBIs) are emerging in many domains such as care, sustainable energy and water management. This paper examined three initiatives in Dutch water management, focusing on their relationship with water boards. CBIs present issues that water boards find difficult to respond to because of two reasons. First, CBIs are demarcated very differently from the formal tasks that water boards pursue. This calls for internal alignment within water boards to respond adequately. Second, CBIs necessitate external alignment with other water-managing governments. Water boards must therefore implement double helix alignment to relate productively to initiatives emerging in society.     

Business and project strategy alignment: ICT project success in Iran

This study aims to examine the relationship and alignment between business and project strategy and their impact on the success of information and communications technology (ICT) projects. The proposed conceptual model was tested through structural equation modelling (SEM), with an analysis of SmartPLS based on survey data from 144 firms. The results indicate that project success is positively influenced by project strategy, while business strategy shows no impact on project success. In addition, alignment between business strategy and project strategy affects project success positively.     

Size effect of carbon fiber-reinforced silicon carbide composites (C/C-SiC): Part 2 - tensile testing with alignment device

The appropriate assessment of mechanical properties is essential to design ceramic matrix composites. The size effect of strength plays a key role for the material understanding and the transfer from lab-scale samples to components. In order to investigate the size effect for carbon fiber-reinforced silicon carbon (C/C-SiC) under tensile load, a tensile testing with a minimum of deviation from the pure tensile loading is necessary. Hence, a hybrid edge/face-loading test device for self-alignment and centering of C/C-SiC tensile samples was developed, evaluated and proved to ensure pure tensile load. The mechanical analysis of more than 190 samples with two different cross-sections fabricated from the same material population revealed no significant difference in tensile strength. Although the volume under load was increased from 129 to 154 mm³, the tensile strengths of 162 ± 7 and 164 ± 6 MPa did not change. These results are discussed regarding the weakest link and energetic size effect approaches.     

定向碳纳米管填充橡胶复合材料的制备

采用传统的橡胶工艺制备了高取向碳纳米管(CNTs)填充5%和30%的橡胶复合材料。碳纳米管的取向可能是在球磨的优化过程中由拖曳剪切力引起的。与纯橡胶相比,碳纳米管的选择性取向使其弹性模量能都得到了提高。     

Structure-based analysis of Bacilli and plasmid dihydrofolate reductase evolution

Dihydrofolate reductase (DHFR), a key enzyme in tetrahydrofolate-mediated biosynthetic pathways, has a structural motif known to be highly conserved over a wide range of organisms. Given its critical role in purine and amino acid synthesis, DHFR is a well established therapeutic target for treating a wide range of prokaryotic and eukaryotic infections as well as certain types of cancer. Here we present a structural-based computer analysis of bacterial (Bacilli) and plasmid DHFR evolution. We generated a structure-based sequence alignment using 7 wild-type DHFR x-ray crystal structures obtained from the RCSB Protein Data Bank and 350 chromosomal and plasmid homology models we generated from sequences obtained from the NCBI Protein Database. We used these alignments to compare active site and non-active site conservation in terms of amino acid residues, secondary structure and amino acid residue class. With respect to amino acid sequences and residue classes, active-site positions in both plasmid and chromosomal DHFR are significantly more conserved than non-active site positions. Secondary structure conservation was similar for active site and non-active site positions. Plasmid-encoded DHFR proteins have greater degree of sequence and residue class conservation, particularly in sequence positions associated with a network of concerted protein motions, than chromosomal-encoded DHFR proteins. These structure-based were used to build DHFR specific phylogenetic trees from which evidence for horizontal gene transfer was identified.     

Simulation of high-resolution X-ray microscopic images for improved alignment

The introduction of precision optical elements to X-ray microscopes necessitates fine realignment to achieve optimal high-resolution imaging. In this paper, we demonstrate a numerical method for simulating image formation that facilitates alignment of the source, condenser, objective lens, and CCD camera. This algorithm, based on ray-tracing and Rayleigh-Sommerfeld diffraction theory, is applied to simulate the X-ray microscope beamline U7A of National Synchrotron Radiation Laboratory (NSRL). The simulations and imaging experiments show that the algorithm is useful for guiding experimental adjustments. Our alignment simulation method is an essential tool for the transmission X-ray microscope (TXM) with optical elements and may also be useful for the alignment of optical components in other modes of microscopy.