可控源音频大地电磁测深在隐伏断裂勘察中的应用研究

为了给城市工程建设规划提供基础地质资料,需查明区内断裂的准确位置、产状以及覆盖层厚度。利用CSAMT方法进行了勘察工作,为避免区内人文干扰和电磁的严重干扰,野外施工时采用了多种手段以保证观测数据的可信度;数据处理时首先利用五点平滑进行去噪处理,然后利用空间滤波消除静态效应,最后采用基于遗传算法的CSAMT全资料反演程序对野外数据进行反演。分析反演结果并结合已知地质资料,给出了区内断裂的准确位置等信息。     

Influence of the High-Speed Rail on the Spatial Pattern of Regional Tourism – Taken Beijing–Shanghai High-Speed Rail of China as Example

This paper compares volumes, flows, and spatial patterns of traffic before and after the opening of the high-speed rail (HSR) link between Beijing and Shanghai. Evidence emerges of a significant change in the shape of isochrones within the region. Under the influence, the temporal and spatial distance between the source region and tourist destination is greatly reduced. Equally, multiple contact modes are more apparent and the overall structure of tourism flow network is closer after the opening of the HSR service. As can be seen from the above, the HSR has a significant impact on regional tourism traffic accessibility and then has a significant on the temporal and spatial distribution of regional tourism resource. The tourism flow will respond positively to the “space compression” effect.     

Modeling domestic holiday tourism demand in Australia: Problems and solutions

An econometric model is very useful for understanding the underlying relationship between tourism demand and economic variables such as income and travel prices. However, a long time series horizon of data is essential to run an econometric model that is consistent with economic theory. Although time series data on the number of domestic trips and visitor nights in Australia are available since 1978–79, breaks in the time series in different years have made it difficult to estimate a domestic holiday demand model. It is because the data series in different periods are not directly comparable. In this study, a simple data adjustment technique has been used to obtain comparable data series. Among several econometric demand models, a single equation multivariate time series demand model in a double log linear functional form was found to be the most appropriate and practical model to estimate and analyze the demand parameters of domestic holiday travel in Australia. However, the model with variables in level terms was observed having the “spurious regression problem” which has been corrected using the cointegration and error correction mechanisms. The estimated income and price elasticity of domestic holiday travel demand are consistent with economic theory and therefore can be used for forecasting and other purposes.     

瑞利衰落信道中MC-CDMA系统的载波频率偏移性能

多载波CDMA（MC－CDMA）技术结合了OFDM和CDMA技术的优点，在无线衰落信道中传输高速数据时具有突出的性能。但由于MC－CDMA采用了多载波技术，载波频率偏移对系统性能的影响非常大。本文对瑞利衰落信道下存在载波频率偏移的MC－CDMA系统性能进行了理论分析并对误码率进行了详细讨论。     

Variable Selection and Shrinkage: Comparison of Some Approaches

A common strategy within the framework of regression models is the selection of variables with possible predictive value, which are incorporated in the regression model. Two recently proposed methods, Breiman's Garotte (B reiman , 1995) and Tibshirani's Lasso (T ibshirani , 1996) try to combine variable selection and shrinkage. We compare these with pure variable selection and shrinkage procedures. We consider the backward elimination procedure as a typical variable selection procedure and as an example of a shrinkage procedure an approach of V an H ouwelingen and L e C essie (1990). Additionally an extension of van Houwelingens and le Cessies approach proposed by S auerbrei (1999) is considered. The ordinary least squares method is used as a reference.
With the help of a simulation study we compare these approaches with respect to the distribution of the complexity of the selected model, the distribution of the shrinkage factors, selection bias, the bias and variance of the effect estimates and the average prediction error.     

卡尔曼预测滤波在脱靶量时滞问题中的应用研究

针对光电跟踪系统中的脱靶量时滞问题,对脱靶量时滞对系统控制性能的影响进行了分析。在机动目标运动模型的基础上提出了可行的预测滤波解决方案,设计了对应的卡尔曼滤波器。仿真结果表明对脱靶量的预测取得了良好的效果。     

锁相接收机环路参数选取的一些考虑

本文结合工程实际，推导了某种锁相接收机锁相环传递函数，并就如何选取锁相环环路参数问题进行了分析与设计。     

近10年外商在华直接投资的空间分异及成因分析

首先选取2000—2009年的相关数据分析了我国三大地区FDI的基本情况,然后从投资数量和相对增值率两个方面分析得出我国FDI的空间分异的特征,最后利用2010年的相关数据从市场、产业集聚效应、成本、GDP等4种因素分析了影响我国FDI空间分异的原因。     

Measuring Diagnostic Accuracy of Statistical Prediction Rules

Many different statistical methods have been developed for predicting the disease classes of patients. However, in order to have confidence in the results of such methods, their performance needs to be assessed. Different performance measures are reviewed and the circumstances in which they are relevant are described. Subtleties exist which must be taken into account to ensure that the measure chosen matches the objectives. Examples are given showing different interpretations of future diagnostic performance.     

An examination of the forward prediction error of U.S. dollar exchange rates and how they are related to bid-ask spreads,purchasing power parity disequilibria,and forward premium asymmetry

Using a panel data approach, we find statistically significant evidence that bid-ask spreads and deviations from purchasing power parity (PPP) are related to the forward prediction error of ten major U.S. dollar exchange rates over the post Plaza Accord period. Previous literature suggests that bid-ask spreads proxy for liquidity risk and deviations from PPP are a source of time-varying risk premiums. Additionally, the paper provides evidence that the forward discount bias is asymmetric with respect to the sign of the forward premium as well as to an undervalued and overvalued U.S. dollar.