Nowcasting and predicting data revisions using panel survey data

The qualitative responses that firms give to business survey questions regarding changes in their own output provide a real‐time signal of official output changes. The most commonly used method to produce an aggregate quantitative indicator from business survey responses—the net balance or diffusion index—has changed little in 40 years. This paper investigates whether an improved real‐time signal of official output data changes can be derived from a recently advanced method on the aggregation of survey data from panel responses. We find, in a New Zealand application, that exploiting the panel dimension to qualitative survey data gives a better in‐sample signal about official data than traditional methods. Out‐of‐sample, it is less clear that it matters how survey data are quantified, with simpler and more parsimonious methods hard to improve. It is clear, nevertheless, that survey data, exploited in some form, help to explain revisions to official data. Copyright © 2009 John Wiley & Sons, Ltd.     

房地产公司物业财务管理系统软件的设计与实现

使用java语言作为前台访问数据库的工具,使用MYSQL数据库作为后台的数据库管理系统,设计和实现了一个房地产公司物业财务管理系统,能够完成管理用户权限及业主物业费、停车费、电费等财务信息。     

Forecasting Australia's real house price index: A comparison of time series and machine learning methods

We employ 47 different algorithms to forecast Australian log real house prices and growth rates, and compare their ability to produce accurate out-of-sample predictions. The algorithms, which are specified in both single- and multi-equation frameworks, consist of traditional time series models, machine learning (ML) procedures, and deep learning neural networks. A method is adopted to compute iterated multistep forecasts from nonlinear ML specifications. While the rankings of forecast accuracy depend on the length of the forecast horizon, as well as on the choice of the dependent variable (log price or growth rate), a few generalizations can be made. For one- and two-quarter-ahead forecasts we find a large number of algorithms that outperform the random walk with drift benchmark. We also report several such outperformances at longer horizons of four and eight quarters, although these are not statistically significant at any conventional level. Six of the eight top forecasts (4 horizons × 2 dependent variables) are generated by the same algorithm, namely a linear support vector regressor (SVR). The other two highest ranked forecasts are produced as simple mean forecast combinations. Linear autoregressive moving average and vector autoregression models produce accurate olne-quarter-ahead predictions, while forecasts generated by deep learning nets rank well across medium and long forecast horizons.     

考虑固体颗粒的自由喷流噪声的数值研究

研究固体颗粒对喷流流场和声场的影响.选取6种不同的湍流模型，对自由喷流进行稳态计算分析，对比发现RNG k-ε模型最适合用于稳态喷流数值模拟；采用LES模型计算喷流的非稳态结果，并结合FW-H方程进行了喷流声场分析，与试验数据进行对比，验证了数值模型的正确性；在此模型的基础上，添加固体颗粒研究其对自由喷流流场和声场的影响，仿真结果表明固体颗粒的存在减小了喷流流场的超音速段长度，显著提高了喷流温度；增大了喷流下游区域噪声，减小了中上游区域噪声.      

基于特征价格模型的沈阳市商品住宅价格指数

为了分析沈阳市商品住宅市场情况,根据国内外编制价格指数的方法,结合沈阳市房地产市场的实际情况,采用特征价格法对沈阳市商品住宅价格指数进行研究.选择16个特征变量,采用半对数模型构建沈阳市商品住宅特征价格模型,并对模型进行检验,确定影响沈阳市商品住宅价格的14个特征变量及相互关系.通过价格指数计算公式,计算出2006年至2013年沈阳市商品住宅特征价格指数,得出沈阳市商品住宅价格增速正在逐年减缓的结论,并对未来市场可能出现的问题提出合理建议.     

非线性测量系统实时在线自动校准

本文提出实时在线自动校准方法，并用该方法减小非线性测量系统的测量误差。     

阵发混沌和阵发同步:噪声在周期信号控制时空混沌中的作用及机制

当外加适当频率和强度的周期信号时,一维等离子体驱动耗散非线性漂移波方程中的时空混沌态能够被成功控制到空间有规的层流态;通过在驱动波坐标系中将系统变换成一组在周期势中运动的耦合振子(模式),模式之间的广义相同步被认为是控制的机制之一.本文的研究则发现,足够强的外加噪声可以使控制后空间有规的系统出现时空混沌的阵发;.在逐渐增大噪声强度时,层流态被越来越多阵发的时空混沌运动打断,直至最后都变成了无规运动;.而在时空混沌的阵发阶段,相位滑移导致模式之间的广义相同步也失去了.     

单圆柱微通道内流动特性实验研究

采用Micro-PIV实验系统和压差测试系统，研究了含有单个微圆柱的通道内去离子水在10相似文献   

多MCU应用系统的构架方法

嵌入式应用系统面临实现实时多任务时，多MCU构建的电路系统具有技术难度低、开发周期短等特点。文章介绍了串行总线传输、并行数据传送、数据共享等多MCU系统的构架方法。并举例说明在设计多MCU系统时应根据系统的实际要求，合理选取构架方法，完成MCU之间的协调，实现系统功能，满足实时性和并行性的要求。     

单片机控制系统中软件抗干扰措施

对单片机控制系统的软件抗干扰技术进行了讨论，并详细论述了实时数据采集误差的抗干扰和CPU抗干扰技术。