Symmetry analysis by computer

Approximate locations of axes of symmetry of a 2-dimensional region are detected on the basis of its border. The border, described in terms of certain directional codes, is treated as a regular polygon in a hierarchical manner where a lower level means a greater number of sides. At each level of the hierarchy, the best axis of symmetry is found which for a lower level gives a more accurate position of the unknown axis of symmetry than for a higher level. Along with an axis of symmetry, a certain error is found on the basis of which the degree of symmetry of a 2-dimensional region is defined. Programs are written in FORTRAN IV and are implemented on an EC-1033 computer.     

应用正规溶液理论计算含水体系液液平衡

本文在正规溶液理论基础上，考虑了混合熵效应和长程静电作用，提出了可用于各种含水体系液液平衡计算的普遍方程，以及分子间作用参数与温度的关系式，关联了具有上会溶温度、下会溶温度和两者同时存在的有机物－水体系的液液平衡数据。该普遍方程可用于含水、有机物和（或）电解质的二元及三元体系液液平衡计算。     

On languages accepted by space-bounded oracle machines

Characterizations of classes of languages accepted by space-bounded oracle machines are developed. These characterizations are given in terms of the regular sets, certain information about the oracle set, and certain algebraic closure operations.This research was supported in part by the National Science Foundation under Grant MCS77-11360     

The <Emphasis Type="Italic">k</Emphasis>-Track Assignment Problem on Partial Orders

The k-track assignment problem is a scheduling problem in which a collection of jobs, represented by intervals, are to be processed by k machines. Two different jobs can be processed by the same machine only if the corresponding intervals do not overlap. We give a compact formulation of the problem and state some polyhedral results for the associated polytope, working in the more general context where job compatibility stems not necessarily from intervals but rather from an arbitrary strict partial order.This authors research was financially supported by the Portuguese Foundation for Science and Technology (FCT).     

An LR parsing technique for extended context-free grammars

Extended context-free grammars allow regular expressions to appear in productions right hand sides, and are a clear and natural way to describe the syntax of programming languages.In this paper an LR parsing technique for extended context-free grammars is presented, which is based on an underlying transformation of the grammar into an equivalent context-free one.The technique is suitable for inclusion in one-pass compilers: the implementation requires little extensions to the algorithms working for normal LR grammars. Besides describing the parsing method, the paper shows also the algorithms for deriving the parsing tables; tables optimization is also discussed. Finally, this technique is compared with other proposals appeared in the literature.     

Chromaticity-tunable remote LuYAG: Ce phosphor-in-glass film on regular textured glass substrate for white light emitting diodes

All inorganic remote phosphor-in-glass film exhibits excellent properties in high power white light-emitting-diodes (WLEDs) thanks to their easy fabrication and thermal stability. Herein, fabrication of (Lu, Y)₃Al₅O₁₂: Ce³⁺ (LuYAG: Ce)phosphors embedded in borosilicate glass film by the conventional solid state reaction and spin coating technology has been reported. The introduction of Y³⁺ ions reduces the difference of relative growth rate along some directions in growth of LuYAG microparticles, yielding a finer grain with smooth edges. By adjusting the molar concentration of Y³⁺ ions in LuAG phosphor, a series of tunable broadband emission from green to yellow region is observed and maintains excellent thermal stability. Meanwhile, the decay curves of samples with different Y³⁺ are almost same. SEM images show that phosphor particles are homogenously distributed within the glass matrix and keep their original morphology, suggesting the phosphor-in-glass films were synthesized as expected. Finally, a simple WLEDs based on the films was constructed using the commercial blue chip. The correlated color temperature ranging from 4853K to 4627K and high color rendering index from 81.4–79.7 were obtained. Upon the different driving current, the chromaticity coordinates of as-fabricated film exhibit good light color stability. These results bring an inspiring insight to tune the luminescent performance for remote WLEDs.     

关于Abel群的正则完整子半群的一个结果

研究正则完整了半群的若干性质,并由此给出Ａｂｅｌ群是特殊值的几个充要条件。     

寻找多色Ramsey数下界的一个算法

研究了正则的素数阶循环图,提出了计算多色Ｒａｍｓｅｙ数Ｒ（ｑ１,ｑ２,…,ｑｎ）的下界的一个算法,得到４个三色Ｒａｍｅｓｅｙ数的新下界：Ｒ（３,３,１０）≥１０４,Ｒ（３,３,１５）≥２１２,Ｒ（３,３,１６）≥２５８,Ｒ（３,３,１７）≥２８２。     

大规模无线传感器网络正六边形覆盖时的传输容量研究

传输容量是无线传感器网络的重要性能指标之一。该文针对监测覆盖效果最佳的正六边形,利用随机几何理论建立无线传感器网络模型,并根据节点分布情况,推导计算节点距离的累计分布函数和概率密度函数。同时,采用功率控制机制,研究CSMA协议下的网络中断概率和网络传输容量。仿真结果表明：正六边形覆盖监测区域内的系统中断概率较低,网络传输容量较大。而且,空间分组密度、网络编码效率、退避次数和重传次数决定了网络传输容量的大小。这为日后研究无线传感器网络的传输性能提供了理论参考依据。