电气化铁路接触网硬点产生原因及改进措施

电气化铁路接触网硬点一旦形成,很容易造成破坏机车稳定受流,影响电力机车弓网关系,造成严重后果。本文就电气化铁路接触网硬点产生的原因,提出了防范与整治接触网"硬点"的几项措施。     

基于激光雷达点云的树冠分形维数及其算法实现

本文以地面激光雷达点云数据为基础,利用盒计数维数法计算单个树冠的分形维数,并对其进行了自相似特征研究。实践证明了该计算方法的可行性。     

审计理论结构逻辑起点的研究

审计理论研究起点是审计理论的逻辑起点。到目前为止,审计理论的逻辑起点还没有形成一致的定论,不同的研究学者存在着不同种观点。本文根据逻辑起点的内涵,对各个观点进行分析和总结,最后得到的结论是:把审计环境作为审计理论研究的逻辑起点,这具有优势和说服力。     

基于DMC-Ⅱ数码航空摄影测量区域网布设研究

从航空摄影到基础地理信息数据产品的获取包括航空摄影、地面控制、空三加密、内业测图等几个阶段。相片控制测量是航空摄影测量的基础工作,通过空三加密获得内业测图所需的外方位元素数据。随着DMC等数字航摄仪应用到航测生产领域当中,DMC影像数据在全数字摄影测量中发挥了越来越重要的作用。本文利用DMC-II数码航空影像,通过实验对DMC-II数字航摄资料的在西南控制困难地区外业像控的布点方案、基线数量、点位位置采取不同方案进行内业加密问题进行研究、分析,总结区域网布点方案的规律性。     

分布式地矿点源信息系统的构件化体系结构设计

应用数据集市技术、分布式构件技术以及Java技术,本文提出了一种以Internet为运行平台的新的分布式地矿点源信息系统设计方案。文中从数据库体系结构和应用系统的体系结构方面,探讨其构件化体系结构设计的原理与方法。实践结果表明,这种新的设计方案可以使该系统的新一代产品以更低的代价发挥更大的效益。     

中国奖励旅游研究综述

奖励旅游在国外发展较早,体制完备,而我国在这方面刚刚起步,学术界研究甚少。回顾近年来我国奖励旅游的研究情况,探讨目前我国在奖励旅游研究方面的几个热点,同时,展望奖励旅游在我国的发展前景,最后试探性的提出今后奖励旅游的研究方向。希望通过这些探讨,使得奖励旅游在我国得到健康、快速的发展。     

Maxbias curves of robust scale estimators based on subranges

A maxbias curve is a powerful tool to describe the robustness of an estimator. It is an asymptotic concept which tells how much an estimator can change due to a given fraction of contamination. In this paper, maxbias curves are computed for some univariate scale estimators based on subranges: trimmed standard deviations, interquantile ranges and the univariate Minimum Volume Ellipsoid (MVE) and Minimum Covariance Determinant (MCD) scale estimators. These estimators are intuitively appealing and easy to calculate. Since the bias behavior of scale estimators may differ depending on the type of contamination (outliers or inliers), expressions for both explosion and implosion maxbias curves are given. On the basis of robustness and efficiency arguments, the MCD scale estimator with 25% breakdown point can be recommended for practical use. Received: February 2000     

改进DTMF信号检测方案在定点DSP上的实现

讨论了硬件实现双音多频(DTMF)信号检测方案的弊端,比较了MUSIC算法、SB-NDFT算法、FF T算法和Goertzel算法,给出了以改进Goertzel算法为核心的DTMF信号检测的DSP实现方案和 实测结果。实验结果表明,该方案有较好的检出率和抗干扰能力。程序全部使用汇编语言实 现,提高了系统运行的实时性和功能冗余度。     

上市公司财务状况理想点评价模型的构建及实证研究

文章通过对上市公司财务比率进行分析,构建了上市公司财务状况的评价指标体系及其理想点评价模型,并应用变异系数法对上市公司财务指标进行了客观赋权,应用构建的综合评价模型对上市公司财务状况进行了有效、合理的评价。     

Anchor Points, Reference Points, and Counteroffers in Negotiations

Based on the theoretical assumptions that counteroffers are generated through an anchoring-and-adjustment process and that offers are perceived as gains or losses relative to a reference point, predictions were made of how, in a price negotiation, the size of counteroffers vary with proposed selling prices and reservation prices. The predictions were confirmed in two experiments. In Experiment 1, 64 undergraduate students of business administration playing the role of buyers of condominiums were presented proposed selling prices and asked to give a counteroffer which a hypothetical seller would accept or reject. A reference point was induced by telling subjects their reservation price. Before giving a counteroffer subjects were asked to indicate whether it was higher or lower than an arbitrary anchor point. In four different groups of subjects, high vs. low reference point was crossed with high vs. low anchor point. The results showed as expected that the counteroffers were higher for a high than for a low anchor point, and higher for a high reference point when the anchor point was perceived as a gain than for a low reference point when the anchor point was perceived as a loss. In Experiment 2 in which another 48 undergraduate students of business administration participated, the anchor points were the proposed selling prices and the reference point (reservation price) was manipulated by providing estimates of the market price. The results were as predicted, thus suggesting that the proposed selling prices operated as anchor points and that the estimated market prices affected the reservation prices (reference points) so that the selling prices and estimated market prices jointly affected the counteroffers.