A Weighted Combination Forecasting Model for Power Load Based on Forecasting Model Selection and Fuzzy Scale Joint Evaluation

To solve the medium and long term power load forecasting problem,the combination forecasting method is further expanded and a weighted combination forecasting model for power load is put forward.This model is divided into two stages which are forecasting model selection and weighted combination forecasting.Based on Markov chain conversion and cloud model,the forecasting model selection is implanted and several outstanding models are selected for the combination forecasting.For the weighted combination forecasting,a fuzzy scale joint evaluation method is proposed to determine the weight of selected forecasting model.The percentage error and mean absolute percentage error of weighted combination forecasting result of the power consumption in a certain area of China are 0.7439%and 0.3198%,respectively,while the maximum values of these two indexes of single forecasting models are 5.2278%and 1.9497%.It shows that the forecasting indexes of proposed model are improved significantly compared with the single forecasting models.

Safety evaluation of replacement reinforcement quality in abutment contact zones of ultra-high arch dam in first impoundment period based on prototype monitoring

Reinforcement quality evaluation at the abutment is an important research direction. Prototype monitoring and theoretical derivation were integrated to study the replacement reinforcement quality in abutment contact zones of the Xiaowan ultra-high arch dam. The principles of monitoring layout and design are introduced in detail. Prototype monitoring shows that the increment of the interfacial compressive stress is much larger in the impoundment stage than in the regulating stage. The water pressure and time-effect are two main factors affeeting the interfacial stress. The time-effect is the key factor in the initial impoundment stage, and the water pressure is the key factor after impoundment. The contact properties are significantly improved by grouting. This study shows that there are three typical stages in the joint opening hydrographs, namely the compression stage, opening stage, and stable stage. There is a nonlinear relationship between the joint opening and temperature, which can be well described by the S-function. In conclusion, the reinforcement effect is satisfying, and the abutment is safe.

The Accuracy of Characteristic Length Method on Failure Prediction of Composite Pinned Joints

A two-dimensioual stress analysis was developed to evaluate the failure of composite joints using characteristic length method. In this study, the accuracy of characteristic length method on the prediction of failure strength and failure mode using different failure criteria was investigated. The stresses required for evaluating the joints were computed from stress functions obtained from displacement expressions that satisfy boundary conditions of the hole. The available experimental data for joint strength in literature were compared with the predicted failure loads and modes of failure for different composite pinned joints. No single failure criterion utilized to evaluate the failure gave a universally best fit across the three joints evaluated. However, the accuracy of characterizing the joints failure varies with joint laminate and choice of failure criterions.

Evaluation of Radiographic Diagnosis on Osteoarthrosis of the Temporomandibular Joint.

Eight-four cadaver specimens of temporomandibular joint were used for the comparison of the results shown in standard lateral tomographs and Shuller’s position films with the macroscoopic observations on the bone and cartilage changes. The results and conclusions were as follows: 1. The