Methods for backcasting,nowcasting and forecasting using factor‐MIDAS: With an application to Korean GDP

We utilize mixed‐frequency factor‐MIDAS models for the purpose of carrying out backcasting, nowcasting, and forecasting experiments using real‐time data. We also introduce a new real‐time Korean GDP dataset, which is the focus of our experiments. The methodology that we utilize involves first estimating common latent factors (i.e., diffusion indices) from 190 monthly macroeconomic and financial series using various estimation strategies. These factors are then included, along with standard variables measured at multiple different frequencies, in various factor‐MIDAS prediction models. Our key empirical findings as follows. (i) When using real‐time data, factor‐MIDAS prediction models outperform various linear benchmark models. Interestingly, the “MSFE‐best” MIDAS models contain no autoregressive (AR) lag terms when backcasting and nowcasting. AR terms only begin to play a role in “true” forecasting contexts. (ii) Models that utilize only one or two factors are “MSFE‐best” at all forecasting horizons, but not at any backcasting and nowcasting horizons. In these latter contexts, much more heavily parametrized models with many factors are preferred. (iii) Real‐time data are crucial for forecasting Korean gross domestic product, and the use of “first available” versus “most recent” data “strongly” affects model selection and performance. (iv) Recursively estimated models are almost always “MSFE‐best,” and models estimated using autoregressive interpolation dominate those estimated using other interpolation methods. (v) Factors estimated using recursive principal component estimation methods have more predictive content than those estimated using a variety of other (more sophisticated) approaches. This result is particularly prevalent for our “MSFE‐best” factor‐MIDAS models, across virtually all forecast horizons, estimation schemes, and data vintages that are analyzed.     

基于MIDAS技术的数据库安全代理的设计与实现

目前国内的数据库应用系统，多数是在Client／Server模式主流商用数据库产品环境下进行开发和运行，其安全级别较低。由于不可能对商用数据库产品进行修改，从应用实际出发，提出由数据库安全代理增强数据库应用系统的安全性。在分析数据库应用系统特点和安全需求基础上，结合实际系统研究了数据库安全代理的功能和在MIDAS技术基础上的设计和实现，并对其抵御常见数据库攻击手段的能力进行了分析和实验。     

基于三层C/S模式下的数据传输系统的设计与实现

论述了三层C/S模式的基本概念,重点讨论了Socket连接下的三层C/S模式在Delphi中的编程技术,解决了企事业单位中的数据传输问题。     

建筑结构设计软件动力时程分析功能比较

利用SATWE、MIDAS/Building和ETABS软件分别对结构地震作用进行计算以获得其在地震作用下的反应,来判断结构整体的安全性和可靠性.对3种软件在前处理、分析过程中、后处理3方面进行对比,得出在前处理中MIDAS/Building在建模、选波和调波方面具有一定的优势,并且在后处理方面提供了丰富的后处理功能,便于操作人员快速查询结果.     

Real‐Time Forecasts of Inflation: The Role of Financial Variables

We present a mixed‐frequency model for daily forecasts of euro area inflation. The model combines a monthly index of core inflation with daily data from financial markets; estimates are carried out with the MIDAS regression approach. The forecasting ability of the model in real time is compared with that of standard VARs and of daily quotes of economic derivatives on euro area inflation. We find that the inclusion of daily variables helps to reduce forecast errors with respect to models that consider only monthly variables. The mixed‐frequency model also displays superior predictive performance with respect to forecasts solely based on economic derivatives. Copyright © 2012 John Wiley & Sons, Ltd.     

Delphi与Multi-tiered应用开发

概述了数据库应用技术的发展历程，介绍了三层应用的结构及优点，以开发工具Delphi为例阐述了三层应用的工作原理与开发。     

应用Delphi4的MIDAS构件组开发起重机零部件管理系统

Delphi自版本4就开始提供一组新的构件MIDAS,使用它,可以方便地开发具有三层体系结构的数据库应用程序。本文分析了MIDAS构件组的开发原理,并以起重机为例,论述了开发基于三层结构的起重机零部件管理系统的基本步骤,并详细讨论了开发中三层结构的实现过程。     

Some heteronemerteans (Nemertea) from the Solomon Islands

Three species of heteronemerteans are recorded from the Solomon Islands. Baseodiscus quinquelineatus has previously been reported from the islands, but Notospermus tricuspidatus has not. The third species, Kukumia solomonensis gen. et sp. nov., is fully described and illustrated. We compared the 18S rDNA gene sequence from this species with five other heteronemertean species from which the sequence of this gene is known. Phylogenetic analysis using three palaeonemertean species as outgroup corroborated a relationship with lineid taxa.     

基于网络的信息管理系统的发展

基于我们社会网络建设的快速发展和网络应用领域的快速扩大，信息管理系统也向着网络化发展的现状，本文着重分析了单层数据库系统和多层数据库系统以及多层数据库中Clients/Server开发模式和MIDAS技术的区别和应用。     

对刘益正负开方术的新研究

刘益在中国古代数学史上最先引入系数可为负数的方程，并突破了方程首项系数必须为１的限制，以往人们认为有了增乘开方程，只要知识正负数的四则运算便可十分容易地推广到高次方程的数值解。