露天—地下复合开采时利用生物定位方法揭露地下开采空洞

本文介绍了利用生物定位方法揭露地下采空区的方法，该方法已在乌克兰、俄罗斯、美国、西欧和澳大利亚得到实际应用；本文阐述了这种方法的实质，列举了一些操作实例，分析了所取得的结果，指出了今后研究和推广应用的方向。     

提高梯级水电站水工建筑物安全运行的措施

介绍谢列布良斯克２号，上、下捷里别尔斯克等３个梯级水电站运行中的实践经验。对运行中土坝渗流量超出设计渗流量，进行了计算研究，并采取相应的防渗措施，如设反滤层等；对水电站工作轮室、蜗壳等处的金属衬砌外壳出现了补强灌浆。     

Kinetic and equilibrium studies in removing lead ions from aqueous solutions by natural sepiolite

The capacity of sepiolite for the removal of lead ions from aqueous solution was investigated under different experimental conditions. The Langmuir and Freundlich equations, which are in common use for describing sorption equilibrium for wastewater-treatment applications, were applied to data. The constants and correlation coefficients of these isotherm models for the present system at different conditions such as pH, temperature and particle size were calculated and compared. The equilibrium process was well described by the Langmuir isotherm model and the maximum sorption capacity was found to be 93.4 mg/g for the optimal experimental condition. The thermodynamic parameters (DeltaG(o), DeltaH(o) and DeltaS(o)) for lead sorption on the sepiolite were also determined from the temperature dependence. The influences of specific parameters such as the agitation speed, particle size and initial concentration for the kinetic studies were also examined. The sorption kinetics were tested for first order reversible, pseudo-first order and pseudo-second order reaction and the rate constants of kinetic models were calculated. The best correlation coefficients were obtained using the pseudo-second order kinetic model, indicating that lead uptake process followed the pseudo-second order rate expression.     

Improvement of thermal contact resistance by carbon nanotubes and nanofibers

Interfacial thermal resistance results of various nanotube and nanofiber coatings, prepared by chemical vapor deposition (CVD) methods, are reported at relatively low clamping pressures. The five types of samples examined include multi-walled and single-walled nanotubes growth by CVD, multi-walled nanotubes grown by plasma enhanced CVD (PECVD) and carbon nanofibers of differing aspect ratio grown by PECVD. Of the samples examined, only high aspect ratio nanofibers and thermally grown multi-walled nanotubes show an improvement in thermal contact resistance. The improvement is approximately a 60% lower thermal resistance than a bare Si-Cu interface and is comparable to that attained by commercially available thermal interface materials.     

Design of an integrated sensor for in vivo simultaneous electrocontractile cardiac mapping

While there is extensive mapping of the spread of electrical activity in the heart, there have been no measurements of electrical and localized mechanical, or contractile, activity. Yet the development of effective treatments for diseases like chronic heart failure and cardiac hypertrophy depend on the ability to quantify improvements in electrocontractile function. In this paper, we present a sensor that is capable of making simultaneous, electrocontractile measurements. Its small size facilitates placement in multiple myocardial sites for multichannel studies. Semiconductor strain gages are used for force sensing, and Ag/AgCl-plated tungsten electrodes act as electrogram sensors. The sensor contains electronics on-board, including instrumentation amplifiers and a microprocessor for data sampling and analog-to-digital conversion. Each sensor can accurately detect 0-245+/-5 mV in two electrogram channels with a sensitivity of 0.96+/-0.2 mV/step and less than 2% error, and 0-144+/-29 g of contractile force with a sensitivity of 0.56+/-0.11 g/step in the analog-to-digital conversion and less than 6% error. The sensor has been tested in vivo in open-chest rabbit and pig mapping studies. These studies indicated that the average peak-to-peak contractile force at the apex is smaller in the rabbit than the pig (13.3 versus 40.3 g), that the average peak-to-peak contractile force in the pig is smaller near the base than near the apex (31.3 versus 40.3 g), and that contractile force is visibly decreased during ventricular fibrillation compared to normal sinus rhythm.     

Improved emission uniformity from a liquid-jet laser-plasma extreme-ultraviolet source

Many modern compact soft-x-ray and extreme-ultraviolet (EUV) imaging systems operate with small fields of view and therefore benefit from the use of small high-brightness sources. Such systems include water-window microscopes and EUV lithography tools. We show that the photon losses in such systems can be minimized while uniformity of object-plane illumination is maintained by controlled scanning of the source. The improved collection efficiency is demonstrated both theoretically and experimentally for a scanned laser-plasma source compared with static sources. A prospective aerial image microscope and a liquid-xenon-jet laser-plasma source are offered as examples of modern imaging tools that may benefit from such scanning of the source.     

Performance of the Keck Observatory adaptive-optics system

The adaptive-optics (AO) system at the W. M. Keck Observatory is characterized. We calculate the error budget of the Keck AO system operating in natural guide star mode with a near-infrared imaging camera. The measurement noise and bandwidth errors are obtained by modeling the control loops and recording residual centroids. Results of sky performance tests are presented: The AO system is shown to deliver images with average Strehl ratios of as much as 0.37 at 1.58 microm when a bright guide star is used and of 0.19 for a magnitude 12 star. The images are consistent with the predicted wave-front error based on our error budget estimates.