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991.
A. V. Shenoy 《Colloid and polymer science》1984,262(4):319-337
A state-of-the-art review on drag reduction has been presented in order to bring out some important aspects of the drag reduction phenomenon and its potential for practical use. The review is biased towards micellar systems and discusses in detail the morphological differences between drag reducing polymeric and micellar systems. Work relating to polymeric systems has not been dealt in detail as it has been the subject of earlier reviews. Studies relating to biological additives as well as suspensions have been briefly mentioned without detailed discussion as their potential for practical use presently appears] to be limited.NCL-Communication No. 3384 相似文献
992.
Yong Lee 《Optical Review》1996,3(5):303-305
We show by computer simulation that a coupled-cavity-type multilayered structure is suitable for the transmissive compensation of group-velocity dispersion for optical pulses of subpicosecond length, and can thus be used to make a simple, compact, and transmissive dispersion-compensation device. 相似文献
993.
Let Гr,n—r denote the infimum of all number Г > 0 such that for any real indefinite quadratic form inn variables of type (r, n—r), determinantD ≠ 0 and real numbers c1; c2,…, cn, there exist integersx
1,x2,…,xn satisfying 0 < Q(x1+c1,x2 + c2,…,xn + cn) ≤(Г|Z > |)1/n. All the values of Гr,n—r are known except for г1,4. Earlier it was shown that 8 ≤Г1,4 ≤16. Here we improve the upper bound to get Г1,4 < 12. 相似文献
994.
K. Urbanowski 《Foundations of Physics Letters》1993,6(2):167-189
A quantum-mechanical model of a detector monitoring the decay of an unstable object is constructed. Detailed investigation of the time evolution of this model shows that under some conditions the non-decay probability of many successively measured unstable particles coincides with that following from the state-reduction postulate. The probability of realizing continuous measurement without the Zenoparadox is demonstrated for this model. 相似文献
995.
The solvent-free reduction of benzophenone and five substituted benzophenones with sodium borohydride to the corresponding alcohols was studied by thermal analysis, X-ray powder diffractometry, NMR spectroscopy, and scanning electron microscopy. In most cases, the reaction occurs via liquid eutectic phases that are formed between the benzophenone and the resulting benzohydrol. Nevertheless, this reaction can be carried out without the need for a solvent, leading to pure alcohol without side products. In some cases, heating may be necessary to achieve a reasonably short reaction time. In conclusion, this reaction type appears to be feasible as a preparative organic reaction that avoids a solvent.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
996.
The nonsymmetric Lanczos method has recently received significant attention as a model reduction technique for large-scale systems. Unfortunately, the Lanczos method may produce an unstable partial realization for a given, stable system. To remedy this situation, unexpensive implicit restarts are developed which can be employed to stabilize the Lanczos generated model.This work was supported in part by ARPA (US Army ORA4466.01), by ARPA (Grant 60NANB2D1272), by the Department of Energy (Contract DE-FG0f-91ER25103) and by the National Science Foundation (Grants CCR-9209349 and CCR-9120008). 相似文献
997.
废水中铜银的分离和银的回收研究黄秀山(四川三峡学院化学系万县634000)关键词分解电压,还原电势,回收一、引言本实验采用电解还原的方法回收贵金属银。目前此法主要用于回收废水中的铬、汞等,对银的研究很少。曾有人进行过自然渗析还原法回收银的研究。用自然... 相似文献
998.
A split-spectrum processing technique for an ultrasonic flaw detection system has been developed which improves the flaw-to-grain echo ratio in large-grained materials. The enhancement is achieved by partitioning a wide-band received spectrum to obtain frequency shifted bands, which are then processed to suppress the grain echoes with respect to the flaw echo, using a novel signal minimization algorithm. Experimental data for titanium and stainless steel samples are presented which show superior flaw detection capabilities for the minimization algorithm with respect to frequency averaging techniques. 相似文献
999.
1000.
Letters in Mathematical Physics - Suppose we are given a compact Riemannian manifold (Q,g) with a completely integrable geodesic flow. Let G be a compact connected Lie group acting freely on Q by... 相似文献