A damage identification technique for CF/EP composite laminates using distributed piezoelectric transducers

In this study, a damage identification approach was developed for carbon fibre/epoxy composite laminates with localized internal delamination. Propagation of the Lamb wave in laminates and its interaction with the delamination were examined. The fundamental symmetric Lamb wave mode, S₀, and the lowest order shear wave mode, S₀^′, were chosen to predict damage location. A real-time active diagnosis system was therefore established. This technique uses distributed piezoelectric transducers to generate and monitor the ultrasonic Lamb wave with narrowband frequency. The two-way switches were employed to minimize the number of transducers. A signal-processing scheme based on the time–frequency spectrographic analysis was utilised to extract useful diagnostic information. Also, an optimal identification method was applied on damage searching procedure to reduce errors and obtain the diagnostic results promptly. Experiments were conducted on [0/−45/45/90]_s CF/EP laminates to verify this diagnosis system. The results obtained show that satisfactory detection accuracy could be achieved.     

A Novel Athermal 40-Channel DWDM Multi/Demultiplexer Based on the Combination of AWGs and Interleaver

An athermal 40-channel dense wavelength-division-multiplexing multi/demultiplexer using a novel combination technology is proposed. It consists of one 1times4 100- to 400-GHz spacing interleaver filter and four sub-arrayed-waveguide gratings (AWGs). The temperature-dependent wavelength shift of the combined device is successfully suppressed to 0.058 nm in the -20degC to 70degC temperature range. Moreover, the combined device's adjacent crosstalk (typically -35 dB) is much better than conventional AWGs (typically -25 dB).     

固井防窜剂的优选试验研究

针对固井过程中经常发生的环空气窜问题，在分析其机理的基础上，对胜利油田及周边地区常用的5种防窜剂的性能进行了试验评价。结果表明：防窜剂DZP2和PZ-2具有较强的抗侵蚀能力，且为微膨胀类型；DZP-2可以提高水泥石抗折强度，PZ-2可以较大幅度地提高水泥石抗压强度；DZP-2和PZ-2具有很好的防窜性能，SPN值都小于3；在试验条件下，DZP-2和PZ-2的最佳加量分别为1．5％～2．0％和1．25％～1．50％。     

催化蒸馏选择加氢的数学模型和模拟

在SHBWR汽液平衡方程、幂函数型动力学方程的基础上，假定每个催化床层为－全混流反应器，建立了碳三催化蒸馏选择加氢数学模型，利用二阶P－K算法进行收敛计算。提出了给反应速率方程添加收敛引子，结合“向上逐层累加”法使模型收敛的方案。     

RLL码的计算机辅助设计

本文着重讨论计算机辅助设计RLL码的具体实现问题.该过程首先根据RLL码两个参数d,k确定一个编码率p/q,然后构造出RLL码的高阶状态转换-输出符号矩阵并求相应的近似特征向量.最后通过状态分裂和状态归并过程,即可得到一个满足d,k约束的编码输出表.其中状态转换-输出符号矩阵为实现计算机辅助设计RLL码提供了有效的数据结构,而且要优化RLL码编码器,就必须有选择地进行状态分裂.     

鼻咽癌药物我成像定位仪的光学设计

对药物荧光鼻咽癌定位的光学系统进行理论分析，给出了该系统的光学设计方法和设计结果。光学系统设计包括，激光器出射光束与光纤高效率耦合技术，同光轴非接触两光纤间的光束耦合技术以及获得较好的像清晰度和衬度的技术。     

混合脱水系统爆炸的原因及预防措施

根据氯碱厂生产实际,详细分析了混合脱水系统爆炸的原因,并提出了预防措 施。     

Synthesis and Spectral Properties of Mixed-Ligand Complexes of Lanthanide Perchlorate with Bis-(phenylsulfinyl)ethane and Organic Lewis Bases

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电子词典生产中的SMT工艺

本文讨论了在电子词典生产中的ＳＭＴ工艺，着重阐述了ＳＭＴ工艺流程，列举了一些不良焊接及其产生不良焊接的原因以供参考。     

A Real-World Application of Lane-Guidance Technologies—Automated Snowblower

This paper describes the development process and the initial field test results of an automated snowblower, focusing on one of the more difficult snow removal operations: blowing snow off the freeway alongside a guardrail without the snowblower touching the guardrail. The development process includes transforming this highway winter maintenance operation into a control problem, modeling a snowblower, designing control algorithms, devising a human-machine interface, and equipping a 20-ton snowblower with sensors and an actuator. Specific challenges include modeling the low-speed tire-induced oscillation, designing high-gain automatic control on front wheels while keeping rear steering under driver control, and implementing such a system under practical limitations. A new dynamic deflection tire model is incorporated into a bicycle model to account for the additional lateral dynamics. A low-order controller was first generated based on the understanding of the specific control problem and, then, refined and tuned iteratively using linear-matrix-inequality optimization. The initial winter field tests were successfully conducted with embedded magnetic markers along the guardrails installed on the shoulders of Interstate-80 in the Sierra Mountain region close to Donner Summit, CA, during the winter of 2005.