Notice of Retraction3-Dimensional Numerical Simulation Method for the Rock Slope Excavation in Civil Engineering
Rock slope is an unknown and complicated system; As for time series with strong randomization, application of the modified GM(1,1) was much more precise than ordinary GMs by comparison. And for time series with fluctuate positive and negative data, translation of the data and revivification after modeling was introduced to make an expansion of the application of the modified GM(1,1). The fitting and prediction precision was good by applying the modified GM(1,1) to analysis the monitoring stress of certain site of the left bank of Jinping Hydropower station. And by compassion, it was known that the prediction trend was accurate, and gave good ground work for further study. On the contrary, it was an important issue for the establishment of long-term prediction models.
Study and application of displacement time series forecast based on APSO-WLSSVM
The model of wavelet least squares support vector machines(WLSSVM) is optimized by adaptive particle swarm optimization(APSO),and a new model named as wavelet least squares support vector machine based on adaptive particle swarm optimization(APSO-WLSSVM) is put forward.The model combines good time domain,frequency domain resolving ability of wavelet transformation and nonlinear learning ability of SVM.The adaptive particle swarm optimization is used to optimize the parameters of SVM so as to avoid artificial arbitrariness and enhance the forecast accuracy.For comparison,the model of APSO-WLSSVM and the traditional SVM(Gauss kernel function) are used to forecast the same displacement time series.The result shows that the former is better than the latter in forecast accuracy.The model is used to forecast the left back slope and diversion tunnel of Jinping First-stage Hydropower Station.The forecast values are in good agreement with the measured ones,indicating that the APSO-WLSSVM is feasible and precise and can be well applied to the forecast of displacement time series.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.