Behaviors of concrete-filled steel tubular members subjected to combined loading

The present study is an investigation on the behaviors of concrete-filled thin-walled steel tubular members subjected to combined loading, such as compression and torsion, bending and torsion, compression, bending and torsion. ABAQUS software is used in this paper for the finite element analysis (FEA). A comparison of results calculated using this modeling shows generally good agreement with test results. The FEA modeling is then used to investigate the influence of important parameters that determine the ultimate strength of the composite members under combined loading, such as compression and torsion, bending and torsion, compression, bending and torsion. The parametric studies provide information for the development of formulae for calculating the ultimate strength of the composite members subjected to combined loading.     

有机羧酸钠盐对PET结晶和熔融行为的影响

采用差示扫描量热仪研究了5种具有不同取代基的苯甲酸钠盐作为结晶成核剂对聚对苯二甲酸乙二醇酯（HET）结晶和熔融行为的影响，并同滑石粉进行了对比。结果表明，成核剂的加入能明显改变PET的结晶和熔融行为。苯甲酸钠、对苯二甲酸甲酯单羧酸钠和对羟基苯甲酸钠提高既汀的熔融结晶温度（Tc）分别达22．93、21．7和19．37℃，但使PET降解严重；对苯酚钠甲酸钠能够提高Tc达17．75℃且对PET相对分子质量影响很小；对苯二甲酸二钠成核作用最差。低于滑石粉。此外，成核剂的成核能力越强，PET双熔融峰中的低温峰顶温度就越高。     

新型自洁式熔体过滤器

自洁式熔体过滤器由多只并联滤芯和1只旋转阀组成,并联的滤芯可同时工作,还可根据压力降大小依次进行自动切换和反冲洗。1只滤芯反冲洗时并不影响其余滤芯继续工作。滤芯的反冲洗无需使用外来清洁液,而是利用了来用其余几只滤芯的少量过滤液。自洁式熔体过滤器能够进行全自动连续过滤和间歇式反冲洗,用于高温、高压聚合物熔体的过滤,特别适用于废丝纺等过滤器需频繁拆卸、更换及清洗的场合。     

数控超声加工的初步工艺试验

介绍在经过数控化改造的两坐标超声加工机床上所进行数控超声加工的初步工艺试验,并讨论试验结果。     

面向WLAN的MPC852T嵌入式系统设计

MPC852T是Motorola新近推出的MPC866/MPC859T家族中面向低端的一款通信处理器.嵌入式Linux由于其费用低廉及开放源码而具有广阔的发展前景.文中在分析了MPC852T通信处理器和嵌入式Linux操作系统的基础上,将二者结合给出了一种嵌入式硬件系统的设计与实现,以及该硬件系统在无线局域网WLAN中的一种应用.实践证明,该硬件系统具有性能稳定、廉价、可扩展性强、适用面广等优点.     

遗传算法在CDMA网络基站分布规划中的应用

CDMA网络的基站分布规划属于多目标组合优化问题，为此在遗传算法的基础上提出了一种基于成本控制的CDMA网络基站分布规划算法。该算法综合考虑了在CDAM网络规划实际工程中的多种规划目标和要求，能够找到符合CDMA网络建设需要的基站分布方案。     

Luminescent Properties of Nanometer Si with Embedded Structure

Blue luminescence at about 431nm is obtained from epitaxial silicon after C^ implantation,annealing in hydrogen ambience and chemical etching sequentially. When annealed in nitrogen ambience and etched accordingly, there is a much narrower peak at about 430nm. During C^ implantation,C=O compounds are introduced into and embedded in the surface of nanometer Si formed during annealing,at last, nanometer silicon with embedded structure is formed,which contributes to the blue emission.     

Image denoising based on wavelets and multifractals for singularity detection.

This paper presents a very efficient algorithm for image denoising based on wavelets and multifractals for singularity detection. A challenge of image denoising is how to preserve the edges of an image when reducing noise. By modeling the intensity surface of a noisy image as statistically self-similar multifractal processes and taking advantage of the multiresolution analysis with wavelet transform to exploit the local statistical self-similarity at different scales, the pointwise singularity strength value characterizing the local singularity at each scale was calculated. By thresholding the singularity strength, wavelet coefficients at each scale were classified into two categories: the edge-related and regular wavelet coefficients and the irregular coefficients. The irregular coefficients were denoised using an approximate minimum mean-squared error (MMSE) estimation method, while the edge-related and regular wavelet coefficients were smoothed using the fuzzy weighted mean (FWM) filter aiming at preserving the edges and details when reducing noise. Furthermore, to make the FWM-based filtering more efficient for noise reduction at the lowest decomposition level, the MMSE-based filtering was performed as the first pass of denoising followed by performing the FWM-based filtering. Experimental results demonstrated that this algorithm could achieve both good visual quality and high PSNR for the denoised images.     

Frequency domain solution to delay-type Nehari problem

This paper generalizes the frequency-domain results on the delay-type Nehari problem in the stable case to the unstable case. The solvability condition of the delay-type Nehari problem is formulated in terms of the nonsingularity of three matrices. The optimal value γ_opt is the maximal γ∈(0,∞) such that one of the three matrices becomes singular. All sub-optimal compensators are parameterized in a transparent structure incorporating a modified Smith predictor.     

用作图法测定R50的理论分析

研究了步、机枪射击密集度试验中弹着点半经的顺序统计量，给出了作图法测定Ｒ_（５０）的理论分析，得到了作图法是测定Ｒ_（５０）的好方法的结论．