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1.
本文介绍了卫星通信地球站终端技术的发展过程,初步论述了新技术应用的环境,为今后研制卫星通信设备提供某些参考。 相似文献
2.
This article deals with the prediction problem in linear regression where the measurements are obtained using k different devices or collected from k different independent sources. For the case of k=2, a Graybill-Deal type combined estimtor for the regression parameters is shown to dominate the individual least squares
estimators under the covariance criterion. Two predictors ŷ
c and ŷ
p are proposed. ŷ
c is based on a combined estimator of the regression coefficient vector, and ŷ
p is obtained by combining the individual predictors from different models. Prediction mean square errors of both predictors
are derived. It is shown that the predictor ŷ
p is better than the individual predictors for k≥2 and the predictor ŷ
c is better than the individual predictors for k=2. Numerical comparison between ŷ
c and ŷ
p shows that the former is superior to the latter for the case k=2. 相似文献
3.
Forecasting residential burglary 总被引:1,自引:0,他引:1
Following the work of Dhiri et al. [Modelling and predicting property crime trends. Home Office Research Study 198 (1999). London: HMSO] at the Home Office predicting recorded burglary and theft for England and Wales to the year 2001, econometric and time series models were constructed for predicting recorded residential burglary to the same date. A comparison between the Home Office econometric predictions and the less alarming econometric predictions made in this paper identified the differences as stemming from the particular set of variables used in the models. However, the Home Office and one of our econometric models adopted an error correction form which appeared to be the main reason why these models predicted increases in burglary. To identify the role of error correction in these models, time series models were built for the purpose of comparison, all of which predicted substantially lower numbers of residential burglaries. The years 1998–2001 appeared to offer an opportunity to test the utility of error correction models in the analysis of criminal behaviour. Subsequent to the forecasting exercise carried out in 1999, recorded outcomes have materialised, which point to the superiority of time series models compared to error correction models for the short-run forecasting of property crime. This result calls into question the concept of a long-run equilibrium relationship for crime. 相似文献
4.
Make One——基于软件功能构件的通用电子设备模式研究 总被引:2,自引:0,他引:2
首先,指出并分析了基于传统的系统体系结构模式而设计的信息设备与其应用功能之间存在整体堆积性和时空不变性的优缺点;然后,根据先进的信息产品应用功能软件化、构件化的思想,提出一种新的设备与应用功能可互相分离、应用功能构件可重载的Make One设备模式,讨论了Make One模式设备的功能结构特点;进而,给出了一个Make One设备模型的嵌入式容器-构件实现方案;最后,探讨了在互联网环境下Make One模式的应用服务体系。 相似文献
5.
VARMA (vector autoregressive moving average) processes are proposed for modelling cointegrated variables. For this purpose the echelon form is combined with the error correction form. Procedures for estimating the Kronecker indices which characterize the echelon form and for specifying the cointegration rank are discussed. The asymptotic distribution of the coefficient estimators is given. An example based o n US macroeconomic data illustrates the procedure and demonstrates its feasibility in practice. 相似文献
6.
7.
高校网上招生系统的后续开发与研究 总被引:4,自引:0,他引:4
针对目前院校端网上招生录取系统存在的局限性,文章详细介绍了高校网上招生后续开发管理系统的功能,讨论了系统实现中的关键技术及实现方法,指出该系统采用分布式计算技术,建立基于组件的3层C/S模型的体系结构,具有高效性、可伸缩性、开发周期短、安全性高的特点。 相似文献
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10.
核主分量分析是一种输入输出特征非线性变换技术。选择最优或接近最优的非线性变换核函数参数,使类的可分性测度最大,是KPCA应用于特征提取的关键。本文采用高斯变异遗传算法作优化技术,实现了KPCA和GA的集成,适合核函数参数的优化选择。仿真表明,该技术可行、有效。 相似文献