Enlightened sonochemistry

Sonochemistry and photochemistry are initiated by high-energy transient species, which may be prone to mutual interaction. Electronic excitation of solutes by energy transfer from high energy species generated in collapsing bubbles is already supported by experimental evidence. The rates of photochemical reactions can be affected by ultrasound-induced mixing of liquids caused by microstreaming near pulsating cavitation bubbles and shockwaves due to bubble collapse. This may not only improve light absorption but also modify the pathway of reaction by increasing the contact between reagents. Finally, one may speculate about a potentially new chemistry of photoexcited solutes under the extreme conditions inside cavitation microreactors. This work reviews research on the excitation of solutes by sonoluminescence, the combined effects of ultrasound and light on liquid systems and the effect of ultrasound on photocatalytic reactions.     

0.8W/80K直线驱动斯特林制冷机的研制

介绍了一种 0 .8W/ 80 K分置式斯特林制冷机。该制冷机采用当前国外先进的直线电机驱动 ,双活塞对称布置结构。该制冷机已通过军品所要求的环境试验 ,输入功率小于 4 0 W(DC)情况下 ,其 +6 0℃高温环境下制冷量≥ 0 .5 W/ 80 K ,带载 0 .5 W工况下 MTTF已突破 2 0 0 0小时。文中主要论述了其工作原理、结构特点、试验情况。     

一种微型空调器的优化设计

介绍了一种微型空调器的研制背景及设计方案 ,采用仿真优化的设计手段对空调器的制冷、制热系统进行了优化设计 ,实践证明其设计是成功的。同时说明了该型空调器所具有的特点及应用场合     

二氟甲烷分子3a1和2b2轨道的电子动量谱

借助电子动量谱学结合量子化学理论和其他方法可以给出轨道电子在整个空间的分布信息,由此给出电子运动的完备描述[1,2 ] .清华大学电子动量谱学实验室近几年已成功地对甲烷[3] 、异丁烷[4 ] 、环戊烷[5] 、二乙酰等[6 ] 分子的轨道电子动量分布进行了测量.我们利用第二代电子动量谱仪首次对CH2 F2 分子3a1和2b2 轨道的电子动量谱进行测量,并与理论计算结果作了比较.同时还计算了坐标空间和动量空间中电子在x - y平面的密度分布.电子动量谱学最基本的过程是(e ,2e)反应,即电子与靶粒子碰撞而发生的电离过程.而对于(e ,2e)反应,含有大量信…     

Peculiarities of Adsorption of Some Polar Substances from Vapor Phase on a Microporous Clay Adsorbent

The adsorption of polar organic substances (methanol, pyridine, and acetonitrile) and water was studied from the vapor phase on microporous adsorbent prepared by the substitution of polyhydroxyaluminum ions for the sodium ions of natural montmorillonite clay. The differential isosteric heats of adsorption of these substances were calculated and analyzed in a wide range of fillings.     

Optimality Conditions and Geometric Properties of a Linear Multilevel Programming Problem with Dominated Objective Functions

In this paper, a model of a linear multilevel programming problem with dominated objective functions (LMPPD(l)) is proposed, where multiple reactions of the lower levels do not lead to any uncertainty in the upper-level decision making. Under the assumption that the constrained set is nonempty and bounded, a necessary optimality condition is obtained. Two types of geometric properties of the solution sets are studied. It is demonstrated that the feasible set of LMPPD(l) is neither necessarily composed of faces of the constrained set nor necessarily connected. These properties are different from the existing theoretical results for linear multilevel programming problems.     

Analysis of finite dimensional approximations to a class of partial differential equations

In this paper, a unified approach for analysing finite dimensional approximations to a class of partial differential equations boundary value problems (second‐kind Fredholm differential equations) is introduced. The approach is shown to be general despite of its extremely simple form. In particular, it is expected to be useful in the convergence analysis of finite element methods for solving PDE problems. Three specific examples are presented to illustrate the broad applicability of the approach. Copyright © 2004 John Wiley & Sons, Ltd.     

Error estimates for Hermite interpolation on spheres

In this paper, we prove convergence rates for spherical spline Hermite interpolation on the sphere S^d−1 via an error estimate given in a technical report by Luo and Levesley. The functionals in the Hermite interpolation are either point evaluations of pseudodifferential operators or rotational differential operators, the desirable feature of these operators being that they map polynomials to polynomials. Convergence rates for certain derivatives are given in terms of maximum point separation.     

A Constant Bound for Geometric Permutations of Disjoint Unit Balls

   Abstract. We prove that a set of n disjoint unit balls in R ^d admits at most four distinct geometric permutations, or line transversals, thus settling a long-standing conjecture in combinatorial geometry. The constant bound significantly improves upon the Θ (n ^d-1 ) bound for disjoint balls of unrestricted radii.