以LCD为目标的自动定焦判据选择

在光学综合自动测量中 ,使用液晶显示屏作为分划板可以大大简化结构 ,提高效率 ,真正地实现自动测量。由于液晶显示具有对比度低、噪声大等特点 ,所以根据液晶的这些特点以及图像处理和CCD信号接收的特点选择两种适用的判据进行了分析和试验比较 ,并给出了结果。结果表明 ,这两种判别函数都适用于以液晶显示屏为目标和用图像处理方法进行光学参数测量的系统 ,其中锐度判别函数更优于信息熵判别函数 ,前者具有更好的抗干扰性和稳定性 ,而且其判定结果更接近目视清晰度判别     

Revêtements modérés et groupe fondamenttal de graphe de groupes

Let R be a discrete complete valuation ring, with algebraically closedresidue field. Let X be a semi-stable R-curve, with smooth generic fibre. In this paper we study tame coverings of X.     

The Phosphinoboration Reaction

The synthesis of phosphinoboronate esters containing a single P? B bond is reported, together with preliminary reactivity studies towards a range of organic substrates. These compounds add readily to aldehydes, ketones, aldimines, and α,β‐unsaturated enones to give primarily the corresponding 1,2‐addition products containing a new P? C bond. The first examples of transition‐metal‐catalyzed phosphinoborations of C‐C multiple bonds in which P? C and B? C bonds are formed in a single step are also disclosed; allenes react by a highly regioselective 1,2‐addition whereas terminal alkynes undergo a formal 1,1‐addition.     

Arylspiroborates Derived from 4‐tert‐Butylcatechol and 3,5‐Di‐tert‐butylcatechol and Their Antimicrobial Activities

A family of arylspiroborates has been prepared by the addition of either 4‐tert‐butylcatechol or 3,5‐di‐tert‐butylcatechol to boric acid and an alkali metal hydroxide. All compounds were characterized fully using multinuclear NMR spectroscopy and by elemental analyses. A single crystal X‐ray diffraction was carried out on potassium (bis‐(3,5‐di‐tertbutyl[1,2‐benzenediolato(2‐)‐O,O′]borate)) ( 8 ). All compounds displayed appreciable anti‐microbial activities.     

Addition of boranes to N-aryl-salicylaldimines: intramolecular hydrogenation of imines

Addition of boranes to N-aryl-salicylaldimines takes place initially at the reactive phenolic O-H bond to give an activated boron-containing imine and dihydrogen. In some cases a subsequent intramolecular hydrogenation step is observed and the C=N imine bond is reduced to the corresponding amine. Reactions with dimesitylborane in THF are unique in that the reduced amine product is the major product observed in solution.     

Stationary states of crystal growth in three dimensions

A new Markov process describing crystal growth in three dimensions is introduced. States of the process are configurations of the crystal surface, which has a terrace-edge-kink structure. The states are continuous along edges but discrete across edges, in accordance with the very different rates for the two types of captures of particles. Stationary distributions, describing steady crystal growth, are found in general. To our knowledge, these are the first examples of stationary distributions for layered crystal growth in three dimensions. The steady growth rate and other quantities are obtained explicitly for two interacting edges. For many interacting edges, growth behavior is determined (a) in various asymptotic regimes including thermodynamic limits, (b) via simulations, and (c) using series (cluster) expansions in the slope of the surface, the first three coefficients being computed. The theoretical growth rates show a marked dependence on surface dimensions. This may contribute to the size dependence and dispersion in the observed growth rate of small crystals.     

相对论性核碰撞中φ介子增强

用强子和弦级联模型LUCIAE系统地研究了相对论性p+p和Pb+Pb碰撞中φ介子产生.在模型框架内实验测得的158AGeV/cPb+Pb碰撞中φ介子产额相对于同能量p+p碰撞的增强现象,依赖于弦发射胶子的集体效应和奇异夸克压低约化两机制,在一定程度内能得到解释.     

在RHIC的极限碎裂和Ф介子产生(英文)

利用强子和串级联模型LUCIAE研究了PHOBOS的极限碎裂等以及在PHIC进行的Au +Au碰撞中带电粒子多重性的经验标度规律 .对介子的产生机制也通过与带电粒子多重性的比较进行类似的研究 .结果似乎表明在串级碎裂模型中带电粒子和介子有共同的产生机制 .还讨论了PHOBOS经验标度规律的模型依赖性 .     

On the prediction of impact noise,II: Ringing noise

The introduction of legislation regarding the limits of noise in factories has led to the need for the prediction of likely noise levels produced by a machine at the design stage. Part I was concerned with the noise produced by impacting bodies due to the high surface accelerations during the contact period. Part II is concerned with the noise arising from the subsequent free vibration. The radiation efficiency of simple components having various modes of vibration is discussed and presented in the form of charts, which it is hoped will enable the machine designer to predict the ringing noise of a machine at its design stage, once the surface area and mean square surface velocity have been established.