A Novel Segmentation and Feedback Model for Resolving Contention in Optical Burst Switching

A novel segmentation and feedback model (SFM) applied to resolve contention is proposed. Simulation and performance analyses show that the SFM effectively avoids contentions in optical burst switching (OBS). The long delay time of deflection routing and the immature technology of wavelength converters and optical buffers are not deployed in the SFM. The SFM does not only realize fast switching but also allows preemption by higher priority bursts.     

An investigation of the unstable region for dense phase conveying in sliding bed flow

For fine powdered materials, capable of being conveyed in dense phase, a conveying region exists in which instability in flow and pipeline blockage can occur if the pressure gradient available is insufficient to maintain a minimum value of solids loading ratio. A reduction in material flow rate can also lead to pipeline blockage in this region. Conveying trials under-taken with cement are used to illustrate the nature of the problem.     

低掺杂浓度Nd:YVO4激光器的输出特性研究

在对Nd:YVO_4晶体的掺杂浓度和晶体长度对激光器性能的影响进行了分析后,报道了利用掺杂浓度为0.3at％,通光长度为10mm的Nd:YVO_4晶体作为增益介质,带光纤耦合的激光二极管端面抽运的Nd:YVO_4激光器。在抽运功率为27.365W时,获得了14.85W的TEM_(00)模输出,光一光转换效率为60.49％,斜效率达64.5％。     

Schäden durch kerbinduzierte Schwingbrüche

Failures by notch induced fatigue fractures Notches produce local stress concentrations and promote the formation of fatigue cracks. Characteristic types of notches as a result of design, manufacturing and operation are presented and remedial measures are discussed. Examples demonstrate the effect of different kinds of notches on various components.     

矿用立式旋风水膜除尘器除尘性能的试验研究

本文通过对立式旋风水膜除尘器除尘性能的模型试验,揭示了几个主要参数对其除尘性能的影响,确定了合理的取值范围,对该种除尘器的设计和应用提供了依据。     

叠后记录Radon变换压制干扰方法

在叠加剖面中,下伏反射界面的反射信号同相轴呈连续的或带有限个间断点的连续层状图像,各种干扰则呈无规则的图像。对此剖面的振幅数据进行 Radon 变换,即分别向各方向进行投影,层状图像将产生一定形状的光滑曲线,而干扰数据将相互抵消,其剩余数据呈高斯分布。在Radon 域中通过平滑等方法消除这些呈高斯分布的噪声数据,再经 Radon 逆变换,便可获得信噪比较高的叠加剖面。其结果不改变原叠加剖面的分辨率和信号波形特征。理论与实际剖面的处理结果表明,这是一种良好的压制干扰方法。     

Significance of fluid regime in biological filtration

A dispersed flow model previously developed to study substrate utilization in unsaturated media was experimentally verified and its practical application was considered. For this purpose, measurements were made using tap water and a synthetic feed solution. The importance of the change in fluid regime as regards to the simultaneous transport and reaction within biological filters were demonstrated. The effect of drop formation and the breakage of liquid jets inside the filters on substrate utilization was also shown.     

关于电视群信号对光纤副载波调频传输中的信噪比平衡问题的分析

本文对微波副载波用电视群信号调频的光纤传输中的信噪比平衡问题进行了分析,推导出VSB-AM信号在解调后的信噪比表达式,引入了信噪比恶化系数的概念.为了实现多路VSB-AM信号间的信噪比的平衡,相应的微波副载波频偏应有确定的比例关系.     

表面稳定模式铁电液晶的电光特性测试

采用一种改进的高分子膜摩擦定向法成功地实现了表面稳定模式铁电液晶的光学双稳态，对比度大于１４０，响应时间达１００微秒。     

强度型光纤传感器的信号检测系统

本文阐述了一种可提高强度型光纤传感器测量精度的检测系统。该系统利用同一检测电路交替检测信号、参考通道的输出信号，并将信号、参考两通道的检测结果相除，从而消除了因发光二极管光源波动及检测电路系统不稳定所带来的误差。采用同步相关技术抑制了噪声，提高了输出信噪比。实验证明，当时间常数ＲＣ为０．０５Ｓ时，采用该检测系统可获得优于千分之一的零点稳定性和优于２×１０３的输出信噪比。