Anomalous refractive indices of the amplifying medium in a waveguide CO2 laser

The relative changes in refractive index of the amplifying medium in a waveguide CO2 laser have been measured as a function of the inlet and outlet pressures, discharge current, gas flow rate, and intracavity power using an interferometric technique. The experiments have been made for two gas mixing ratios over a wide range of the inlet pressure. Saturated phenomena of the refractive index have been observed for increasing inlet pressure. The output power and the variation in impedance of the amplifying medium have been simultaneously measured. The dependence of the refractive index on the inlet pressure in the absence of the discharge, the electron density, and the estimation of errors in measurements are discussed.     

On the recognition of printed characters of any font and size

We describe the current state of a system that recognizes printed text of various fonts and sizes for the Roman alphabet. The system combines several techniques in order to improve the overall recognition rate. Thinning and shape extraction are performed directly on a graph of the run-length encoding of a binary image. The resulting strokes and other shapes are mapped, using a shape-clustering approach, into binary features which are then fed into a statistical Bayesian classifier. Large-scale trials have shown better than 97 percent top choice correct performance on mixtures of six dissimilar fonts, and over 99 percent on most single fonts, over a range of point sizes. Certain remaining confusion classes are disambiguated through contour analysis, and characters suspected of being merged are broken and reclassified. Finally, layout and linguistic context are applied. The results are illustrated by sample pages.     

Localizing overlapping parts by searching the interpretation tree

This paper discusses how local measurements of positions and surface normals may be used to identify and locate overlapping objects. The objects are modeled as polyhedra (or polygons) having up to six degrees of positional freedom relative to the sensors. The approach operates by examining all hypotheses about pairings between sensed data and object surfaces and efficiently discarding inconsistent ones by using local constraints on: distances between faces, angles between face normals, and angles (relative to the surface normals) of vectors between sensed points. The method described here is an extension of a method for recognition and localization of nonoverlapping parts previously described in [18] and [15].     

用氩气和氯气吹洗的方法从Al—Mg合金中除去钠

用5■公斤批量熔体研究了从Al—Mg合金中除钠,使之降到1ppm水平。采用了不同的方法:用叶轮机械搅拌;叶轮搅拌+MgCl_2盐覆盖;叶轮搅拌+惰性气体(氩气)吹洗,同时用盐覆盖或不用盐覆盖;叶轮搅拌,惰性气体+2％Cl_2吹洗。叶轮有一个单一的气体入口与空心轴相通。本试验给出了Na-时间关系曲线,它是用Na+1/2Cl_2=NaCl反应的化学计算法简单确定的。其理由是气泡熔体的接触面积足够大。在各个试验中发现镁都没有明显的去掉。如果接触面积不够大,除钠应该是由熔体中质量迁移起支配作用。文中也处理了这种情况的动力学。根据各种实验室的试验确定了顶部表面的质量迁移系数。在除去溶解氧的水模型试验中,测定了叶轮不同转速和气体不同流量下的接触面积。这些结果与带有多孔装置的化学工程系统有比较好的一致性。然而,不知道这些结果能否满意地推广到工业规模的装置上。