Microfabrication by X‐ray‐induced polymerization above the lower critical solution temperature

A polymer synthesis method is presented in which chain growth driven by exothermic reaction stimulates a gradual chain collapse. The globular precipitates in such systems can be restrained from coalescing by polymerizing in a quiescent environment. Time‐resolved small‐angle scattering study of the methacrylic acid polymerization kinetics in a quiescent system above its lower critical solution temperature (LCST) in water reveals the following features of this method: (a) growing oligomers remain as rigid chains until a critical chain length is reached, at which they undergo chain collapse, (b) radius of gyration increases linearly with time until a critical conversion is reached, and (c) radius of gyration remains constant after the critical conversion, even while conversion is gradually increasing. Following this self‐stabilizing growth mechanism, we show that nanoparticles can be directly synthesized by polymerizing N‐isopropylacrylamide above its LCST in water. The average size of nanoparticles obtained from a polymer–solvent system is expected to be the maximum extent of reaction spread at that monomer concentration. This hypothesis was then verified by polymerizing N‐isopropylacrylamide above their LCST in water, but by initiating the reaction with X‐rays shielded by a mask. The microfabricated patterns conform well to the size and shape of the mask used confirming that the growing chains do not propagate beyond the exposed regions as long as the reaction temperature is maintained above the LCST. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 429–425, 2006     

Determination of Flow Curves at High Strain Rates using the Electromagnetic Forming Process and an Iterative Finite Element Simulation Scheme

The knowledge of reliable material parameters is an essential requirement for the numerical analysis and planning of forming processes, especially when using high speed forming processes in industry. Therefore, a method was developed and implemented to determine the relationship between yield stress, plastic strain, and strain rate of aluminium alloys at very high strain rates of up to 10,000 s-1 by using the electromagnetic forming process (EMF) of tubular specimens. To determine the associated flow curves, an inverse engineering strategy combining an online measurement technique and multi-physical coupled finite element simulations is used. The results are discussed with regard to the anisotropic behaviour of specific aluminium alloys.     

直接探测测风激光雷达的性能分析

综述了激光雷达大气风场测量的方法，提出了采用直接探测到量三维风场分布的F-P干涉仪方法，简述了测量原理，分析了系统的性能和测量误差，比较了基于分子散射和气溶胶散射的系统测量精度，给出了基于瑞利散射的激光雷达系统方案。     

Optical scattering in beef steak to predict tenderness using hyperspectral imaging in the VIS-NIR region

The objective of this research is to develop a non-destructive method for predicting cooked beef tenderness using optical scattering of light on fresh beef muscle tissue. A hyperspectral imaging system (λ = 496–1,036 nm) that consists of a CCD camera and an imaging spectrograph, was used to acquire beef steak images. The hyperspectral image consisted of 120 bands with spectral intervals of 4.54 nm. Sixty-one fresh beef steaks, including 44 strip loin and 17 tenderloin cuts, were collected. After imaging, the steaks were cooked and Warner-Bratzler shear (WBS) force values were collected as tenderness references. The optical scattering profiles were derived from the hyperspectral images and fitted to the modified Lorentzian function. Parameters, such as the peak height, full scattering width at half maximum (FWHM), and the slope around the FWHM were determined at each wavelength. Stepwise regression was used to identify 7 key wavelengths and parameters. The parameters were then used to predict the WBS scores. The model was able to predict WBS scores with an R = 0.67. Optical scattering implemented with hyperspectral imaging shows limited success for predicting current status of tenderness in beef steak.     

污染扩散瞬时浓度场测量方法的研究

提出了一种以粒子成像、粒子散射和统计光学为理论基础的污染扩散非定常瞬时浓度场的测量原理，设计了大范围瞬时浓度场测量系统，利用该系统对瞬时扩散的浓度场进行了实际测量，通过数字图像分析和处理得到污染扩散的非定常瞬时浓度场。     

粒度控制——页岩、煤矸石空心砖原料制备的关键

阐述了页岩、煤矸石的原料粒度对制砖性能的影响,介绍了几种典型的控制颗粒粒度的工艺方案;简要分析了几种筛分机械的优缺点,着重介绍MVS电磁振动高频振网筛在几个使用现场的应用结果,为制砖企业解决原料生产的难题提供了办法。     

软X射线掠入射光学散射特性的研究

介绍了短波段掠入射表面散射线性模型，并且根据这个理论，分析计算了不同的波长和掠射角对软X射线掠入射光学散射特性的影响。随着波长的减小、掠射角的加大，软X射线掠入射光学散射现象越来越严重。     

The high-resolution time-of-flight spectrometer TOFTOF

The TOFTOF spectrometer is a multi-disc chopper time-of-flight spectrometer for cold neutrons at the research neutron source Heinz Maier-Leibnitz (FRM II). After five reactor cycles of routine operation the characteristics of the instrument are reported in this article. The spectrometer features an excellent signal to background ratio due to its remote position in the neutron guide hall, an elaborated shielding concept and an s-shaped curved primary neutron guide which acts i.a. as a neutron velocity filter. The spectrometer is fed with neutrons from the undermoderated cold neutron source of the FRM II leading to a total neutron flux of 10¹⁰n/cm²/s in the continuous white beam at the sample position distributed over a continuous and particularly broad wavelength spectrum. A high energy resolution is achieved by the use of high speed chopper discs made of carbon-fiber-reinforced plastic. In the combination of intensity, resolution and signal to background ratio the spectrometer offers new scientific prospects in the fields of inelastic and quasielastic neutron scattering.     

胶体中布朗粒子简谐束缚下准直高斯光束的动态光散射

在将散射粒子间的相互作用看作简谐力、入射光为准直高斯光束、散射光为理想平面光波的模型下研究了胶体溶液中布朗粒子的统计特征并求解了动态光散射的散射光电场强度的自相关函数；