On counting interval lengths of interval graphs

Given an interval graph G, the interval count problem is that of computing the minimum number IC(G) of interval lengths needed to represent G. Although the problem of deciding whether IC(G)=1 is equivalent to that of recognizing unit-interval graphs, which is a well-known problem having several efficient recognition approaches, very little is known about deciding efficiently whether IC(G)=k for fixed k≥2. We provide efficient computations of the interval count of generalizations of threshold graphs.     

Empty pseudo-triangles in point sets

We study empty pseudo-triangles in a set P of n points in the plane, where an empty pseudo-triangle has its vertices at the points of P, and no points of P lie inside. We give bounds on the minimum and maximum number of empty pseudo-triangles. If P lies inside a triangle whose corners must be the convex vertices of the pseudo-triangle, then there can be between Θ(n²) and Θ(n³) empty pseudo-triangles. If the convex vertices of the pseudo-triangle are also chosen from P, this number lies between Θ(n³) and Θ(n⁶). If we count only star-shaped pseudo-triangles, the bounds are Θ(n²) and Θ(n⁵). We also study optimization problems: minimizing or maximizing the perimeter or the area over all empty pseudo-triangles defined by P. If P lies inside a triangle whose corners must be used, we can solve these problems in O(n³) time. In the general case, the running times are O(n⁶) for the maximization problems and O(nlogn) for the minimization problems.     

Driving Risk Assessment Using Near-Miss Events Based on Panel Poisson Regression and Panel Negative Binomial Regression

This study proposes a method for identifying and evaluating driving risk as a first step towards calculating premiums in the newly emerging context of usage-based insurance. Telematics data gathered by the Internet of Vehicles (IoV) contain a large number of near-miss events which can be regarded as an alternative for modeling claims or accidents for estimating a driving risk score for a particular vehicle and its driver. Poisson regression and negative binomial regression are applied to a summary data set of 182 vehicles with one record per vehicle and to a panel data set of daily vehicle data containing four near-miss events, i.e., counts of excess speed, high speed brake, harsh acceleration or deceleration and additional driving behavior parameters that do not result in accidents. Negative binomial regression ( AICoverspeed = 997.0, BICoverspeed = 1022.7) is seen to perform better than Poisson regression ( AICoverspeed = 7051.8, BICoverspeed = 7074.3). Vehicles are separately classified to five driving risk levels with a driving risk score computed from individual effects of the corresponding panel model. This study provides a research basis for actuarial insurance premium calculations, even if no accident information is available, and enables a precise supervision of dangerous driving behaviors based on driving risk scores.     

石英晶体微天平的测量仪的研究及应用

研制了一种利用计算机控制测量和数据采集压电石英晶体智能测量仪。硬件通过利用复杂可编程逻辑器件（CPLD）实现频率计数和串行通信功能;软件采用图形化编程语言LabVIEW实现数据采集、实时显示、处理、分析以及保存。利用该测量仪进行了内毒索浓度检测的初步应用。结果表明,该系统可以准确测定0．1ng／L-10μg／L的内毒索浓度。系统具有集成度高、稳定性好和智能化程度高等优点。它为浓度测定和物质反应动力学的研究提供了实时分析的测试手段。     

Anti-fertility effects of fractions from Carica papaya (Pawpaw) Linn. methanol root extract in male Wistar rats

The methanol root extracts of Carica papaya (Pawpaw) are used in eastern Nigeria for the treatment of malaria, hepatitis and jaundice. The aim of this study was to investigate the effects of the fractions isolated from C. papaya methanol root extract on fertility in male Wistar rats using sperm counts, percentage defective sperm cells (morphology), biochemical and hormonal assays as biomarkers. The roots of C. papaya were extracted using 80% methanol for 72 h. Oral acute toxicity study was done with the crude extract for 24 h. The extract was fractionated by column chromatography using petroleum ether, chloroform, ethyl acetate and methanol. The petroleum ether fraction was further fractionated on preparative TLC using ethyl acetate–methanol solvent systems to isolate CPFE 1, CPFE 2 and CPFM 1. The 3 fractions (75 mg/kg) were used to treat male Wistar rats orally for 60 days. Animals were euthanized and testes collected, homogenized and used for sperm count and motility. Plasma and serum were used to assay biochemical parameters including aspartate aminotransferase (AST), blood urea nitrogen (BUN), total bilirubin (TB), alkaline phosphatase (ALP), alanine aminotransferase (ALT), gamma glutamyl transferase (GGT), triglycerides, hormones (LH and FSH). Histopathological study of the testes, kidney, heart and liver were conducted. Acute toxicity result showed that C. papaya root extract produced no mortalities at the dose of 2000 mg/kg but induced CNS-related symptoms as well as diuresis. The fractions significantly (P < 0.01) produced decreases in sperm counts and increased the percentage of defective sperm cells. There were significant (P < 0.05) increases in aspartate aminotransferase (AST) and blood urea nitrogen (BUN). Histopathological studies showed mild kidney and cardiac hyperaemia, slight hepatic degeneration and severe necrosis of the germinal epithelium of the testes. This study calls for some level of caution in the use of these roots and its extracts/fractions in traditional medicine for treating diseases. On the other hand, it could be a good source of drug for birth control.     

在PPLN波导中利用上转换实现通讯波段单光子探测的研究

分析了在周期性极化铌酸锂(PPLN)波导中波长为1.32 μm和1.55 μm的光子和频过程.给出了达到最大信号转换效率所需要的泵浦光功率.分析了该过程中各种可能存在的噪声源,尤其是拉曼过程给出的噪声,给出了利用相干滤波片和标准具来减小噪声的方法.分析了该探测器在量子密码通讯中的应用.     

Micromegas探测器计数曲线、增益以及能量分辨特性的研究

介绍了自行研制的Micromegas探测器的基本结构和工作原理. 在不同工作气体(Ar和CO₂)配比条件下,利用⁵⁵Fe放射源对该探测器的能量分辨、计数曲线和气体增益等特性进行了较为详尽的测试. 对相关结果进行了讨论. 关键词： Micromegas探测器 计数曲线 能量分辨率 增益     

激光拍频信号光子到达时间间隔特性分析

为了得到周期激光拍频信号的频率,从理论上推导了光信号相邻光子到达时间间隔满足的概率密度函数(PDF),以数值计算为基础,对周期性激光拍频信号进行详细分析,得到了稳定光强信号和周期拍频信号光子到达时间间隔PDF曲线形状的差别,从该差别中能够获取信号的拍频频率。设计了验证实验光路系统,采用多像素光子计数器(MPPC)记录光子时间,对6、8、10、12MHz拍频信号进行探测,证明了理论分析的正确性。在光子计数频率为拍频频率1/5的条件下,得到较好的实验结果,估计两光束混合效率为0.65。以暗计数噪声为限制条件,分析了该方法能够探测到的最小拍频频率为0.2333MHz。     

双-Poisson模型下盈余首次达到给定水平的时间分析

本文运用鞅的方法研究了双 Poisson模型下盈余首次达到给定水平的时间 ,得到了它的矩母函数以及相应的期望、二阶和三阶中心矩的具体表达式 .     

基于相干叠加态的非正交编码诱骗态量子密钥分发

非正交编码协议和诱骗态方法可以有效地抵御光子数分离攻击. 由于相干叠加态中单光子成分高达90%, 常作为单光子量子比特的替代出现, 用于量子信息过程处理和计算. 本文结合非正交编码协议和诱骗态方法提出一种新的量子密钥分发方案, 光源采用相干叠加态, 推导了单光子的密钥生成速率、计数率下限和误码率的上限, 利用Matlab 模拟了无限多诱骗态情况下和有限多诱骗态情况下密钥生成速率和传输距离的关系, 得出该方案可以提升密钥生成速率并且提高安全传输距离, 验证了该方案可以进一步提高量子密钥分发系统的性能.