Soft-spring nonlinear vibrations of antisymmetrically laminated rectangular plates

This paper deals with the effects of initial geometric imperfections and in-plane boundary conditions on the large-amplitude vibration behavior of angle- and cross-ply rectangular thin plates. It is found that the presence of imperfection amplitudes of the order of only half the total laminated-plate thickness may significantly raise the vibration frequencies and change the large-amplitude vibration behavior from the well-known hard-spring to soft-spring behavior. The effects of fibre angles and bending-stretching coupling for angle-ply plates and Young's moduli ratios and number of layers for antisymmetric cross-ply plates are examined.     

标识化语言的发展及在电子物流中的应用

重点阐述了XML技术的发展和对EDI技术的有效补充与改进，并展望基于XML技术的电子商务物流数据交换技术的发展前景。     

中条山供水工程取水首部电气设计的特点

对70m落差下大型泵站供电设计中电缆的受发热这两个难点进行了论述，并通过应用特种电缆和工程塑料解决了这些难题，使泵站的设计能够较好地满足安全、便利运行的要求，为地质条件较为复杂的情况下设计泵站提供了一个比较理想的模式。     

电潜泵中压变频调速系统的改进

电潜泵中压变频器输出端产生高次谐波和脉冲电流 ,对电潜泵电动机的绝缘性能和轴承寿命造成不利影响。为此 ,提出 3项改进对策 :①采用谐振软性开关逆变电路 ,使功率开关器件在零电压条件下导通 ;②在变频器逆变输出端设置电抗滤波器抑制高次谐波电流 ;③改变电动机内部结构 ,如加大定子槽宽 ,增加转子导条尺寸 ,变星接法为星 角接法 ,采用绝缘轴承等。实践证明 ,采取改进对策后 ,不仅提高了电潜泵的产量 ,而且变频器滤波后电动机端的过电压明显减小 ,电潜泵和电缆的寿命延长     

减压渣油与FCC油浆共炭化的化学组成变化

考察了齐鲁石化胜利炼油厂催化油浆（FCC）和胜利减压渣油（VR）在490℃，0.8MPa下不同混合比的原料和不同反应时间的中间产物的HS、TS、PS、P及其1h中间产物的HS和TS的^1H-NMR。数据结果反映了体系的反应速度。掺入FCC油浆抑制了VR的反应活性，降低了体系的反应速度，增加了基质的溶解度；1h中间产物的组成结构更接近于原料及反应体系的反应性和基质的溶解度；1h中间产物的芳香度越高，取代基越少，侧链越短，基质对VR中的活性反应组分在炭化早期生成的高度缩合物质的溶解度越大。     

入侵检测及网络层安全的研究

随着计算机网络的迅速发展，网络安全问题正变得日益重要。文章介绍了计算机网络系统IP层安全概况和入侵者对IP层常采用的入侵手段，以及为防止这种入侵所采取的措施。     

Colour Centres and Energy Transfer in BaF2-xClx:Eu2+ Phosphors

The optical absorption spectra of BaF2-xClx:Eu2 after ultraviolet (UV) light excitation were investigated.The differences between the absorption spectra after and before excitation (DAS) were observed.The DAS increase at both the high and the low energy side of F band in BaF2-xClx:Eu2 after 245 nm UV light excitation.The bleach effect of UV light and the absorption of electrons in the valence band may account for the former and the formation of Fa centres (association of F(Cl-) centres), whose absorption band matches the HeNe laser better, may explain the latter.In the write-in process, the transfer of electrons is via tunneling.In the readout process, the transfer of electrons captured in F(F-) and Fa centres is more likely via tunneling, and that of F(Cl-) centres is more likely via conduction band.     

黄土丘陵沟壑区王家沟流域水文特征分析

王家沟流域属暖温带大陆性季风气候,冬季严寒少雪,春季干燥多风,夏季酷热多雨,秋季温凉适中,雨热同季,当地常见暴雨历时大多在2h以下,这种短历时、大强度的暴雨最易引起水土流失。分析了流域治理前后径流泥沙的来源情况,为同类型小流域综合治理提供科学依据。     

An experimental study of an optical burst switching network based on wavelength-selective optical switches

In this article we report the system structure and test results of an experimental optical burst switching network with three edge router's and one core node. Wavelength-selective switches developed for this system and their characteristics are depicted. The implementation and performance of our new scheme for the just-in-time protocol are described. We also report experimental results of FTP and VOD services on this system. Some parameters, including traffic rate, average burst data length, and assembly time, are studied.     

富氧燃烧技术在梭式窑中的应用

研究了富氧燃烧技术对梭式窑烧成的影响.研究结果表明,随着氧浓度从21%-30%的逐渐增加,CO总浓度和NO总浓度都先明显下降,后缓慢上升;节能效果在初始段较为明显,而后效果不明显;而实际烟气量与氧浓度成反比,与过剩空气系数成正比.