多探头扫描探针显微镜系统

虽然扫描探针显微镜具有高分辨率等优异性能，但不足之处也显而易见。较低的扫描和采样速度使工作效率不高。多探针或多探头的概念就是为提高扫描探针显微镜的工作效率而提出的。为了摸索多探头扫描探针显微镜的特点和解决半导体工业晶片检测的实际需求，我们设计了四探头SPM。本文主要介绍我们研制的四探头扫描探针显微镜系统，并探讨多探头SPM的设计方法。     

A fast low‐density parity‐check code simulator based on compressed parity‐check matrices

Low‐density parity‐check (LDPC) codes are very powerful error‐correction codes with capabilities approaching the Shannon's limits. In evaluating the error performance of an LDPC code, the computer simulation time taken becomes a primary concern when tens of millions of noise‐corrupted codewords are to be decoded, particularly for codes with very long lengths. In this paper, we propose modeling the parity‐check matrix of an LDPC code with compressed parity‐check matrices in the check‐node domain (CND) and in the bit‐node domain (BND), respectively. Based on the compressed parity‐check matrices, we created two message matrices, one in the CND and another in the BND, and two domain conversion matrices, one from CND to BND and another from BND to CND. With the proposed message matrices, the data used in the iterative LDPC decoding algorithm can be closely packed and stored within a small memory size. Consequently, such data can be mostly stored in the cache memory, reducing the need for the central processing unit to access the random access memory and hence improving the simulation time significantly. Furthermore, the messages in one domain can be easily converted to another domain with the use of the conversion matrices, facilitating the central processing unit to access and update the messages. Copyright © 2011 John Wiley & Sons, Ltd.     

Explication and sharing of design knowledge through a novel product design approach

At the beginning of the 21st century, the emergence of knowledge management is viewed as a natural evolution. Knowledge management is defined as the formal management of knowledge for facilitating creation, access, and reuse of knowledge, typically by using advanced technology. To be easily communicated and shared, tacit knowledge has to be explicated as explicit knowledge (e.g., in product specification or a scientific formula or production rules); and this explicit knowledge has to be shared as applicable data through the use of information technology. Product design is such a business process that a great part of the design knowledge is often a tacit type, being difficult to share, or available only in forms of natural language documents. However, the expertise recorded in these documents is an essential resource of successful competition in the market. This paper presents a knowledge explication and sharing approach; specifically focusing on the knowledge management of modular product design. The solution approach involves modeling modular products, formulating the explicit knowledge, discovering new design knowledge with data mining, and sharing the knowledge with web services technology. The proposed approach is to be applied to an actual case of motherboard design/assembly in one of the largest PC manufacturing enterprises.     

串列双圆柱在规则波中的压力分布

本文通过实验研究，测定了串列双圆柱在规则波中柱表面压力，分析了定常压力和脉动压力沿柱周向的分布，对并列、串列双圆柱的升力进行了适当的讨论，结果表明，两柱的压力分布、升力均与两柱间距有关。     

Registration and integration of multiple laser scanned data for reverse engineering of complex 3D models

In reverse engineering or rapid prototyping of a complex 3D object, there is often a need to scan a complete 3D model using laser digitizers. However, most digitizers scan objects in a 2.5D way such that the multiple data sets need to be aligned and integrated. In this paper a surface registration algorithm is proposed to solve the problem using a nonlinear minimization approach. Multiple data sets with different orientations can thus be aligned and integrated to construct a complete 3D data set. To control the accuracy of the registration process, uncertainty analysis of the registration parameters is investigated. A registration uncertainty model is developed to predict the uncertainty of the registration process. Using this model, we can predict the minimum number of the scanned data points to satisfy the required registration accuracy.     

On‐Demand Droplet Collection for Capturing Single Cells

Droplet‐based microfluidic techniques are extensively used in efficient manipulation and genome‐wide analysis of individual cells, probing the heterogeneity among populations of individuals. However, the extraction and isolation of single cells from individual droplets remains difficult due to the inevitable sample loss during processing. Herein, an automated system for accurate collection of defined numbers of droplets containing single cells is presented. Based on alternate sorting and dispensing in three branch channels, the droplet number can be precisely controlled down to single‐droplet resolution. While encapsulating single cells and reserving one branch as a waste channel, sorting can be seamlessly integrated to enable on‐demand collection of single cells. Combined with a lossless recovery strategy, this technique achieves capture and culture of individual cells with a harvest rate of over 95%. The on‐demand droplet collection technique has great potential to realize quantitative processing and analysis of single cells for elucidating the role of cell‐to‐cell variations.     

Comparison of physicochemical properties and aqueous solubility of xanthone prepared via oil-in-water emulsion and complex coacervation techniques

The aim of this study was to enhance aqueous solubility of xanthone with natural polymers using oil-in-water emulsion and complex coacervation as the microencapsulation techniques. There was no interaction between xanthone and the wall material; and xanthone crystallinity was decreased as observed via fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and x-ray powder diffraction (XRD) after microencapsulation. Oil-in-water emulsion and coacervation increased xanthone solubility by 37-fold and 1.6-fold, respectively. However, O/W emulsion method required a high ratio of oil to xanthone. The solubilizing effect of oil and wall material, particle size reduction, and decreased crystallinity were responsible for enhancing the aqueous solubility of xanthone.     

光固化聚氨酯甲基丙烯酸树脂胶的研究

通过甲基丙烯酸与过量的异氰酸酯反应，制得聚氨酯甲基丙烯酸树脂胶粘剂。它可以用于光固化，得到的固化物具有优良的力学性能和储存稳定性。研究了某些因素对合成过程的固化性的影响。     

Liquid chromatography at critical conditions of polyethylene

Olefin copolymers are of increasing scientific interest due to their important application potential. Liquid chromatography can deliver important information, especially on their molecular structure. In particular, liquid chromatography at critical conditions (LCCC) is of interest because, in this chromatographic mode, the elution is molar mass independent for a given repeat unit. LCCC is conducted at conditions where the entropic effect of size exclusion is equal to the enthalpic effect of interaction between the macromolecules and the stationary phase and can be used to separate copolymers as well as some homopolymers containing one single repeat unit but having different end groups. For the first time, critical conditions for linear PE were experimentally identified by using porous graphite (Hypercarb™) as the stationary phase, and either 1-decanol/ortho-dichlorobenzene (ODCB), 1-decanol/1,2,4-trichlorobenzene (TCB), n-decane/ODCB, or n-decane/TCB as the mobile phase at 160 °C. The identified critical conditions for PE using the above approach in the above solvents have been verified to be correct, barring slight deviations, by two different techniques which were previously used to determine critical conditions for polymers soluble at ambient temperature. The critical conditions for polyethylene were applied to separate statistical copolymers of ethylene/1-octene with similar molar mass.