Wu J.,Lanzhou University |
Wang J.,Lanzhou University |
Lu H.,University of Technology, Sydney |
Dong Y.,Lanzhou University |
Lu X.,Lanzhou Branch of Changzheng Engineering Co.
Energy Conversion and Management
For an energy-limited economy system, it is crucial to forecast load demand accurately. This paper devotes to 1-week-ahead daily load forecasting approach in which load demand series are predicted by employing the information of days before being similar to that of the forecast day. As well as in many nonlinear systems, seasonal item and trend item are coexisting in load demand datasets. In this paper, the existing of the seasonal item in the load demand data series is firstly verified according to the Kendall τ correlation testing method. Then in the belief of the separate forecasting to the seasonal item and the trend item would improve the forecasting accuracy, hybrid models by combining seasonal exponential adjustment method (SEAM) with the regression methods are proposed in this paper, where SEAM and the regression models are employed to seasonal and trend items forecasting respectively. Comparisons of the quartile values as well as the mean absolute percentage error values demonstrate this forecasting technique can significantly improve the accuracy though models applied to the trend item forecasting are eleven different ones. This superior performance of this separate forecasting technique is further confirmed by the paired-sample T tests. © 2013 Elsevier B.V. All rights reserved. Source
Li K.,Lanzhou Branch of Changzheng Engineering Co. |
Dong B.-C.,Lanzhou Branch of Changzheng Engineering Co. |
Yin J.-J.,Lanzhou Branch of Changzheng Engineering Co. |
Zhang X.,Lanzhou Branch of Changzheng Engineering Co. |
And 2 more authors.
Huaxue Gongcheng/Chemical Engineering (China)
Assessing flow pattern of gas-liquid two-phase flow is crucial to calculating pressure drop for it. In terms of assessing flow pattern for gas-liquid two-phase flow, the Baker and Griffith-Wallis Graphs are widely used by engineers for manual calculation in order to get some rough accessing results used in some place, but they are restrained to link computer programs as a more efficient and accurate calculations. In order to obtain the functions of dividing area lines, the data regressions using the Origin for the Baker and Griffith-Wallis Graphs were applied. Then it is programmed via C++ Language to make the whole calculation processes as an integral computer programming session. From the experimental data of simulation results, it concludes that with the help of computer calculation programs, it can rapidly and accurately assess the forms for two-phase flow of both in vertical and horizontal piping systems, and calculate the pressure drop in two-phase flow piping systems using homogeneous process and Dukler-Method. Computer programming can greatly increase the calculation efficiency especially when trying to figure out iteration computing problems in Dukler-Method pressure drop calculations, which is practically used. From the cases' study of some relevant standards and codes, it is considered as a feasible and accurate method in this field. ©, 2015, Editorial Office of Chemical Engineering (China). All right reserved. Source