基于S-CDMA的HFC接入网技术分析

针对HFC网络上行信道的噪声和干扰特性,论述一种基于S-CDMA(同步码分多址)技术的上行信道传输方案,对S-CDMA技术及工作原理和系统组成进行分析,给出了S-CDMA在有线电视宽带网中的具体应用。     

输出功率为21.5W的单端抽运Nd:YVO4/LBO单频激光器

采用中心波长为888nm的激光二极管作为抽运源,减轻了Nd:YVO4晶体中的热效应。通过合理的谐振腔设计,扩大激光晶体处的基模尺寸和振荡光在凹面腔镜处的入射角,减轻了激光晶体内部的热效应和谐振腔像散,提高了激光器的输出功率。采用四镜环形腔选模的办法,获得稳定的高功率单频激光输出。在吸收的抽运功率为67.5W时,实现了最高功率为21.5W的532nm单频激光输出,其8h功率稳定性优于±1%,光束质量M2<1.1,光-光转换效率为31.9%。     

斯托克斯光种子法固体相干反斯托克斯拉曼频移器的理论研究

以波动方程和受激拉曼散射(SRS)物质方程为基础,采用光种子法,建立了固体相干反斯托克斯拉曼频移器的归一化耦合波方程,研究了晶体中反斯托克斯光转换效率。在脉冲抽运条件下分析了归一化增益系数G、归一化相位失配系数ΔK以及一阶斯托克斯光种子的归一化光场振幅ψs0三个变量对固体相干反斯托克斯拉曼频移器的影响,并作出了一系列相应曲线,由所得曲线估算了各归一化变量的合理取值范围。分析结果表明,在ΔK=0时,通过增大sψ0来打破拉曼增益抑制的影响,其转换效率峰值可达到44%。而当sψ0较弱时,可选取合适的相位失配系数,反斯托克斯光转换效率可达40%。     

适合LD泵浦的Tm:YAG的研究

研究了ＴｍＹＡＧ激光晶体的光谱特性，重点分析了适合ＬＤ泵浦的优越性和ＴｍＹＡＧ中ＯＨ根对激光性能的影响。     

同步泵浦飞秒非临界相匹配红外光参量振荡器

采用非临界相匹配方式，制成一台同步泵浦飞秒红外光参量振荡器。其输出波长的调谐是靠改变泵浦光掺钛蓝宝石激光器的输出波长而得以实现的，其调谐范围为１．０８～１．１３ｕｍ。在９０ｆｓ．１．１ｗ左右的掺钛蓝宝石激光器的泵浦下，同步泵浦光参量振荡器的输出功率为１００ｍｗ．而脉竟只有６０ｆｓ左右。     

LD泵浦微型YAG激光器的单模连续运转

本文报道了793nmLD泵浦YAG激光器TEM_(00)模的连续运转,描述了实验系统,给出了实验结果,讨论了模式匹配、光谱匹配、阈值功率和斜率效率等问题。     

抽油机节能技术应用和常见问题的分析及应对策略

利用抽油机设备采油是目前石油行业原油开采中最为常见的采油方式.在抽油机设备上探索"开源"与"节流"节能技术对于原油开采具有较大意义.通过分析高转差率电动机、低压变频启动装置在现场应用的优势、问题及应对策略,以及油井合理工作制度的分析、摸索和调整,从而得到抽油机能耗最优解.实践证明,各项节能技术现场应用效果都比较显著,如将各种技术有效结合,扬长避短,就能真正做到节能降耗,提高整体产业优势.     

Thermal-hydraulic performance of novel louvered fin using flat tube cross-flow heat exchanger

Experimental studies were conducted to investigate the air-side heat transfer and pressure drop characteristics of a novel louvered fins and flat tube heat exchangers. A series of tests were conducted for 9 heat exchangers with different fin space and fin length, at a constant tube-side water flow rate of 2.8 m³/h. The air side thermal performance data were analyzed using the effectiveness-NTU method. Results were presented as plot of Colburn j factor and friction factor f against the Reynolds number in the range of 500–6500. The characteristics of the heat transfer and pressure drop of different fin space and fin length were analyzed and compared. In addition, the curves of the heat transfer coefficients vs. pumping power per unit heat transfer area were plotted. Finally, the area optimization factor was used to evaluate the thermal hydraulic performance of the louvered fins with differential geometries. The results showed that the j and f factors increase with the decrease of the fin space and fin length, and the fin space has more obvious effect on the thermal hydraulic characteristics of the novel louvered fins. __________ Translated from Journal of Shanghai Jiaotong University, 2007, 41(3): 380–383 [译自: 上海交通大学学报]     

赤泥浆体泵送胶结充填采矿法研究

我院与山东铝业公司共同进行的赤泥浆体泵送胶结充填采矿新技术、新工艺研究，开创了无水泥胶结充填的先例，成功地解决了湖田铝土矿的采矿方法难题，避免了地表陷落，保护了自然环境。同时大幅度降低了充填成本，从根本上解决了充填对井下巷道的污染，为山东铝业公司工业废料的利用开辟了新的途径。本文简要介绍了赤泥浆体胶结充填材料的特性、充填料制备及泵压输送工艺、倾斜分条充填采矿法工业试验及效果。     

Microfluidic arrays for bioimprint of cancer cells

We report the development and characterization of a microfluidics-based bioimprint process using high-density microchannel arrays for cell-culture and polymer delivery. The tubeless PDMS arrays consist of multiple independent microchannels and allow for parallelized bioimprint via automated dispensing and passive pumping. Using the microchannels, a 400 nm thin test pattern was replicated into a methacrylate biopolymer to demonstrate process applicability. Bioimprints of cobalt chloride stimulated Ishikawa endometrial cancer cells exhibiting exocytosis-like pore structures were compared with controls using AFM to exemplify a process application. The devices can be used for high-throughput cell assays, cell developmental studies and the formation of phenotype-specific biomimetic scaffolds.