陕西省引红济石调水工程1#支洞塌方原因分析及对策

塌方是隧洞施工过程中经常遇到的难题,本文针对引红济石工程1#支洞在施工过程中出现的两次塌方原因进行分析,总结出隧洞施工过程中避免塌方的主要方法和策略,具有普遍的借鉴意义。     

利用光纤数字同步传送网2.048 Mbit/s支路传送高精度标准时间信号

首次提出一种利用光同步数字传送网的2.048Mbit/s信号传送高精度时间编码信号的方法和实验结果。它可以使整个通信网的交换机、计费系统、网管系统、基站控制器等设备实现与UTC的时间同步。目前的实验证明,时间同步的不确定度优于±5μs。     

Direct imaging of a high-power diode laser cavity using a transparent indium-tin-oxide (ITO) contact

We describe a novel "see-through" indium-tin-oxide contact on the n-side of a high power unstable resonator semiconductor laser (URSL) that allows direct observation of the cavity during high power operation. Under optimized annealing conditions this transparent ITO contact has a low enough specific contact resistivity to permit normal high power CW operation of the URSL and allows the observation of filamentation. This contact scheme is applicable to a wide range of semiconductor lasers and is especially appropriate for high power devices. The same structure can also be used to obtain a 2-D thermal map of the laser cavity.     

全断面双护盾掘进机在引黄工程断层破碎带的卡机处理

万家寨引黄工程国际Ⅱ、Ⅲ标已查明的断层有34条，隐伏断层可能还有一些，除了利民堡区域性大断层（F32）外，较大的集中于7#洞北段59＋700—68＋820，主要有F65、F70、F90、F74。全断面双护盾掘进机适应于较复杂的地质条件，因此在通过断层破碎带时一般都较正常。但在通过引黄工程区域性大断层F65时，发生了卡机事故，处理用了3个月时间。该文对处理TBM卡机事故的施工进行了总结。     

激光光束质量因子的研究进展

本文详细分析了各种光场下光束质量M2因子。在不同的场中,A.E.Siegman当初所定义的M2因子,已经有了很大的变化,因而M2因子的特性也与当初不同,不仅M2因子可以大于等于1,而且可以小于1,甚至小于0。其反映的物理意义,也从经典场中的衍射极限倍数,变化为非经典场中的准直性量度以及对空间相干性的某些反映。此外还列举并分析了几种特殊的光束质量因子,最后讨论了M2因子应用的问题并指出了其局限性。     

基于Mega8单片机和AD9833的正弦波信号发生器

正弦波信号作为一种基准信号广泛应用于各种电路中，产生正弦波信号的方法有很多种，DDS（Direct Digital Frequency Synthesis直接数字频率舍成器）作为一种新型技术，具有相对带宽宽，频率转换时间短，频率分辨率高，控制灵活方便等优点，成为现代频率合成技术中的佼佼者。AD公司生产的AD9833是一款低功耗、可编程波形发生器，在Mega8单片机的控制下可生成0-12．5MHz的正弦波，还可以生成三角波和方波。经现场验证，基于Mega8单片机和AD9833的正弦波信号发生器，可以非常方便地生成各种频率的正弦波。     

Reactive energy measurement using frequency controlled analog-to-pulse-rate converter

Contents This paper analyzes a problem of phase shifting and deseribes a novel method for electronic reactive energy measurement. The proposed measurement structure, composed of an integrator as a phase shifting circuit and a frequency controlled analog-to-pulse-rate converter, provides for the measurement completely in accordance with IEC definition of reactive energy, which is performed with simple but high performance metering device.

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Die Blindverbrauchsmessung anhand eines netzsynchronisierten Analog-Frequenz-Wandlers

Übersicht In diesem Artikel wird das Problem der Phasenverschiebung analysiert und eine neue Meßmethode für elektronische Blindverbrauschsmessung aufgezeigt. Die vorgeschlagene Strucktur, bestehend aus einem Integrator als Phasenschieber und netzkontrolliertem Analog-Frequenz-Wandler, ermöglicht die Verwirklichung eines einfachen aber präzisen Elektrizitätszählers zur Messung der Blindenergie, dessen Arbeitsprinzip mit den IEC Empfehlungen vollkommen übereinstimmt.

     

Oral absorption improvement of poorly soluble drug using solid dispersion technique

A new triazol antifungal agent, (+)-2-(2,4-difluorophenyl)-3-methyl-1-(1H-1, 2,4-triazol-1-yl)-3-[6-(1H-1,2,4-triazol-1-yl)pyridazin++ +-3-ylthio]butan-2-ol (MFB-1041), shows poor oral absorption and is practically insoluble in water (1.2 micrograms/ml). Solid dispersion systems with an enteric polymer such as hydroxypropylmethylcellulose phthalate (HP-55) and carboxymethylethylcellulose (CMEC), and a nonenteric polymer, hydroxypropylmethylcellulose (Metolose) were evaluated to improve drug absorption and solubility. The oral bioavailabilities of these solid dispersions in beagle dogs were over 6 times higher than that of a suspension system with increasing drug solubility in an alkaline medium. X-Ray powder diffraction measurement of the solid dispersion showed a complete drug phase change from a crystal to an amorphous state. Further, from the results of a stability test, the preparations were stable in a desiccated condition and the absorption profiles also showed no change. From the results, it was suggested that the oral administrative preparation of MFB-1041 having a superior absorption profile and a high stability could be obtained by a drug phase change from a crystal to an amorphous state, especially in the spray-drying method using enteric polymers.     

Cyanex有机膦类萃取剂在贵金属溶剂萃取中的研究和应用

介绍了近年来Cyanex有机膦类萃取剂在贵金属溶剂萃取中的研究状况及应用进展，展望了该类萃取剂在贵金属分离提取中的应用前景。     

PTA装置自动控制系统实现安稳运行的对策

针对PTA装置的工艺生产特点，对自动控制系统当中出现的不同种类的问题，进行了多方面的简要探讨与分析，并提出实现安稳运行相应的对策。