Simulations of oil spread on a water surface

Numerical simulation of an oil slick spreading on still and wavy surfaces is described in this paper. The so-called sigma transformation is used to transform the time-varying physical domain into a fixed calculation domain for the water wave motions and, at the same time, the continuity equation is changed into an advection equation of wave elevation. This evolution equation is discretized by the forward time and central space scheme, and the momentum equations by the projection method. A damping zone is set up in front of the outlet boundary coupled with a Sommerfeld-Orlanski condition at that boundary to minimize the wave reflection. The equations for the oil slick are depth-averaged and coupled with the water motions when solving numerically. As examples, sinusoidal and solitary water waves, the oil spread on a smooth plane and on still and wavy water surfaces are calculated to examine the accuracy of simulating water waves by Navier-Stokes equations, the effect of damping zone on wave reflection and the precise structures of oil spread on waves.

Chemical kinetics and self-ignition in a model supersonic hydrogen-air combustor

Self-ignition tests of a model scramjet combustor were conducted by using parallel sonic injection of gaseous hydrogen from the base of a blade-like strut into a supersonic vitiated airstream. The range of stagnation pressure and temperature studied varied from 1.0 to 4.5 MPa and from 1300 to 2200 K, respectively. Experimental results show that the self-ignition limit, in terms of either global or local quantities of pressure and temperature, exhibits a nonmonotonic behavior resembling the classical homogeneous explosion limit of the hydrogen-oxygen system. Specifically, for a given temperature, increasing pressure from a low value can render a nonignitable mixture to first become ignitable, then nonignitable again, This correspondence shows that, despite the globally supersonic nonpremixed configuration studied herein, ignition is strongly influenced by the intricate chemical reaction mechanism and thereby exhibits the homogeneous explosion character. Consequently, self-ignition criteria based on a global reaction rate approximating the complex chemistry are inadequate. An auxiliary computational study on counterflow ignition was also conducted to systematically investigate the contamination effects of vitiated air. Results indicate that the net contamination effects for the present experimental data are expected to be substantially smaller than contributions from the individual contamination species because of the counterbalancing influences of the H2O-inhibition and NO-promotion reactions in effecting ignition.

Gain saturation in gas flow and chemical lasers

A theoretical model for gain saturation in gas flow and chemical lasers is presented. The theory is applicable to all possible numerical values of τ/τc, where τ is the characteristie flow time for the flowing gas to move across the laser action region and τc is the characteristic collision relaxation time. The saturation effects of the convection and the "source flow" of the inverted population are revealed. A general relation of gain coefficient and some new gain saturation laws are obtained. For the special case of τ/τc1, the present theoretical results agree with the experimental results on the "anomalous" saturation phenomena in the supersonic diffusion HF chemical laser determined recently by Gross and Coffer[8]. The theory also agrees with the measured results of saturation intensity varying with τ/τc in gas flow CO2 lasers[7]. For the special case of τ/τc1, the present theory is consistent with both the standard theory[1] for gas lasers where the gas has no macroscopic motion and the known gain saturation theory[2-5] for gas flow and chemical lasers.

基于CAN总线的海洋平台数据采集系统

介绍了一种基于CAN总线的数据采集系统,讨论了该系统应用在海洋平台这类特殊环境下的系统结构和现场节点的具体设计。系统由上位监控机、CAN网卡、智能网桥节点和智能采集节点组成,采用总线方式的网络拓扑结构,构成一种基于CAN总线的分布式监控采集系统。智能节点以AT89S52单片机为微控制器,使用SJA1000作为CAN控制器,可构成上行和下行网络通信波特率分别为500kbps和250kbps的CAN网络。详细分析了该系统的硬件组成,应用层协议和通讯流程。系统已应用于某海上平台的环境载荷的监测,提高了数据传输的可靠性,为平台的安全运行和结构的优化设计提供了科学依据。

纳米生物技术

纳米生物技术是纳米技术和生物技术相结合的产物 ,本文主要从生物芯片、分子马达、纳米探针、纳米生物材料以及其他纳米生物技术等方面介绍了此领域里的重要发展

气相爆轰波沿胞格的动力学机理研究

建立了一种以子单元分析为基础，研究气相爆轰波沿胞格运动时的动力学机理的新方法。根据该子单元的性质和斜冲击波关系，首先推导了对撞前后前导冲击波沿胞格对称轴的马赫数之比和入射冲击波入射角及胞格几何性质的关系，求解了胞格结构中的三波点对撞问题。然后，采用爆炸波模拟前导冲击波的自持运动过程，求解气相爆轰波沿胞格的动力学过程,理论分析表明，气相爆轰波在胞格起点首先经历一个增长过程，然后才出现衰减。理论分析结果与实验和数值计算结果的比较表明符合得较好。

膨胀岩中油井套管力学响应分析

针对存在混凝土衬砌与否两种情况,对油井套管 ? 膨胀围岩体系进行了三维轴对称有限元分析.结果表明,在围岩产生的膨胀压力下,存在混凝土衬砌时,径向位移最大值发生于混凝土衬砌与膨胀岩交界处;没有混凝土衬砌时,径向位移最大值在油井套管与膨胀岩的交界处.故完好的混凝土衬砌能明显地减缓膨胀岩对油管套管的挤压作用.在围岩膨胀压力下,油井套管容易发生颈缩现象.

铁基抗高温磨损激光熔覆涂层强韧设计和研究 Ⅱ:Fe-Cr-C-W-Ni激光熔覆层的微观组织及性能

利用ＯＭ、ＳＥＭ、ＴＥＭ研究了Ｆｅ－Ｃｒ－Ｃ－Ｗ－Ｎｉ激光熔覆涂层熔覆态及其高温时效态的微观组织结构。结果表明激光熔覆层组织细小，具有强韧两相组成（奥氏体和Ｍ_７Ｃ_３碳化物）的微观结构特征，高温时效处理组织中有Ｍ_（２３）Ｃ_６、Ｍ_６Ｃ、Ｍ_２Ｃ等新碳化物形成。显微硬度和冲击磨损实验证实了激光熔覆态和峰值时效态熔覆层均具有良好的力学性能。

爆炸处理水下海淤软基

<正>前言爆炸处理水下海淤软基是一项新技术。国家经委、国家教委、中国科学院等单位列为国家第一批100项与企业横向联合的重点科技项目。连云港建港指挥部,中国科学院力学研究所,锦屏磷矿、交通部第三航务勘探设计院等四单位组织科研组联合攻关。经过四年的工程实践、工程性试验、模型和机理试验等,取得了大量系统的数据,写出了近20篇科学技术报告,并由交通部和中国科学院组织了(钅监)定。这些科技报告经由本文作者审定。为了对这项新技术有一个全面的介绍,作者将科研组所提供的报告作一综述,并阐明了自己的一些观点。科研组各单位先后参加工作达40余人,他们在很艰苦条件下取得了这些宝贵的资料(见本文所引文献),作者对于参加这项工作的所有同志,和本文所参考报告的作者们表示感谢!

郭永怀先生诞辰九十周年纪念文集

目录

Time-resolved investigation of low-density plasma channels produced by a kilohertz femtosecond laser in air

By employing pump-probe back longitudinal diffractometry, the electron density and decay dynamics of a weak plasma channel created by a 1-KHz fs laser in air has been investigated. With ultrashort laser pulses of 50 fs and low energy of 0.6 mJ, we observe weak plasma channels with a length similar to 2 cm in air. An analytical reconstruction method of electron density has been analyzed, which is sensitive to the phase shift and channel size. The electron density in the weak plasma channel is extracted to be about 4x10(16) cm(-3). The diameters of the plasma channel and the filament are about 50 and 150 mu m, respectively, and the measurable electron density can be extended to less than 10(15) cm(-3). Moreover, a different time-frequency technique called linearly chirped longitudinal diffractometry is proposed to time-resolved investigate ultrafast ionization dynamics of laser-irradiated gas, laser interaction with cluster beam, etc.

用于大范围高精度实时位移测量的半导体激光干涉仪

现有的半导体激光干涉仪存在测量精度与测量范围的矛盾。本文提出一种新的实时位移测量半导体激光干涉仪，并分析了干涉仪的测量原理。首先提出一种新的解相算法，它通过两路实时相位探测电路从干涉信号中得到待测量相位，消除了光强波动、初始光程差、电路放大倍数、调制深度、Bessel函数等参数对测量精度的影响，提高了测量精度。其次，提出一种扩大测量范围的技术，并用解包裹电路得到真实相位和待测量的位移, 将测量范围从半个波长提高到几个波长。在实验中，测得喇叭的峰峰值为2361.7nm，重复测量精度为2.56nm，测量时间为

稳态下锡电极的轴向温度分布

根据STANNEX氧化锡电极（以下简称锡电极）的热导率曲线，以平壁导热为模型，建立了锡电极中心轴向温度分布的简化模型。根据锡电极使用的实际情况建立实验炉，测试了锡电极在稳态下的边界温度以及锡电极中心在稳态下的实际温度分布。根据实验所测得的边界条件对锡电极的温度分布作了深入细致的推导。用有限差分法求出了锡电极的轴向温度分布，计算结果跟实际测试温度能较好地吻合。对电极导电的牵引材料的选择有很好的指导意义，同时也为玻璃电熔的散热与功率配置以及电极使用过程中的冷却提供了较好的参考。根据实际温度情况采取相应的冷却措

Spectral characterization of transparent (Nd0.01Y0.94La0.05)(2)O-3 laser ceramics

The spectrum properties of transparent (Nd0.01Y0.94La0.05)(2)O-3 ceramics were investigated. It was found that all absorption bands of (Nd0.01Y0.94La0.05)(2)O-3 ceramics are broadened, of which the full width at half maximum of the peak centered at 804 nm is 8 nm and its absorption cross section is 1.02x10(-20) cm(2). The emission cross section of (Nd0.01Y0.94La0.05)(2)O-3 ceramics located at 1078 nm is 5.71x10(-20) cm(2) and its fluorescent lifetime is 0.214 ms, which are similar to those of 1.0 at. %Nd:Y2O3 ceramics. These indicate that (Nd0.01Y0.94La0.05)(2)O-3 transparent ceramics has excellent spectroscopic properties.

化学抛光和退火对钛酸锶基片表面改性研究

Atomic force microscopy (AFM) was applied to study the surface morphology of SrTiO3 substrates which were polished by traditional mechanical and chemical mechanical method respectively. The influence of anneal was also studied. Results show that the RMS of CMP STO substrates can be 0.214 nm. Compared the rocking curve of the unannealed STO substrates with the annealed ones, it indicates that anneal can improve the crystal quality.