Research on Constructing Contours from Regular Terrain Grids Containing Invalid Data

A new method for constructing contours from complicated terrain elevation grids containing invalid data is put forward. By using this method, the topological consistency of contours in groups can be maintained effectively and the contours can be drawn smoothly based on boundaries pre-searching and local correction. An experimental example is given to demonstrate that the contours constructed by this method are of good quality.     

自适应光学系统MEMS微变形镜的研究

指出了传统变形镜研究所面临的瓶颈，以及采用MEMS技术研究微变形镜的优点．介绍了利用静电力驱动的平板电容式分立式微变形镜．分析结果表明它具有比传统变形镜更优越的性能．指出了进一步研究与发展MEMS微变形镜还需要解决的若干重要问题．     

基于Kriging插值的数字地图生成算法研究

提出基于Kriging法进行水深数据插值形成规则网格数字高程模型的算法,对海底数字地图的模拟具有重要参考价值,是海底地形匹配定位技术研究的关键.数字仿真结果证明该算法可行.     

A novel approach for coal seam terrain prediction through information fusion of improved D–S evidence theory and neural network

In order to effectively and accurately forecast the distribution of coal seam terrain, a novel prediction approach through information fusion of improved D–S evidence theory and neural network was proposed. An improved strategy based on confidence level was presented for evidence theory to reduce the conflicts between evidences and enhance the fusion effect. Moreover, BPAs function was constructed reasonably through extracting weights from preliminary prediction values of four neural networks, and the flowchart of proposed approach was designed. Furthermore, a simulation example was provided and some comparisons with other fusion prediction methods were carried out. The simulation example and comparison results indicated that the proposed approach was feasible, high-precision and outperforming others. Finally, an industrial application example of mining automation production was demonstrated to specify the effect of proposed system.     

Simulation research on the influence of eroded primary key strata on dynamic strata pressure of shallow coal seams in gully terrain

In Huojitu Coal Mine of Shendong mining area,the dynamic strata pressure (DSP) accidents occurred when the working faces passed the gully terrain,Focusing on this problem,we used physical simulation ex...     

Development of a simulation model for a three-dimensional wind velocity field using Ténès Algeria as a case study

A mathematical simulation model was developed that can determine the three-dimensional wind velocity field over a complex terrain. The Ténès area in the Valley of Cheliff in Algeria was used as a case study. This region is exposed to south-west circulation that makes it favorable to the use of wind energy. Knowledge of wind fields is crucial for predicting the dispersion of pollutants, for forecasting meteorological weather, for fire spread prediction and in the design and implementation of wind turbines. By means of a mass consistent model, an in-house program was developed to calculate the three-dimensional wind velocity field in the study region. The model was supported by a numerical box in which flow through is allowed for in the upper and lateral boundaries. The bottom boundary through which no flow through occurs was determined by the topographic relief at the surface. From measured wind velocities, observed values were calculated by interpolation-extrapolation. Using an optimization method, the adjusted velocities were obtained from constraints, observed velocities and the continuity equation. The model was verified with wind point data, the relative error did not exceed 6%.     

A novel Temperature–Humidity–Time defrosting control method based on a frosting map for air-source heat pumps

To improve the defrosting accuracy and the energy efficiency of the air-source heat pump (ASHP) under frosting and defrosting conditions, a novel Temperature–Humidity–Time (T–H–T) defrosting control method, based on a frosting map for the ASHP unit, is proposed in this paper. A field test was conducted for two heating seasons, to verify the feasibility and applicability of the T–H–T method. The advantages of the T–H–T method, compared to the conventional Temperature–Time (T–T) defrosting control method, are presented. In total, eight cases are shown in this paper. Cases 1 to 4 were chosen to reveal the T–H–T performance under different frosting conditions. It was found that no matter what kind of frosting conditions, defrosting was always initiated in a similar situation: ∼90% of the outdoor coil surface was covered by frost; the temperature difference between the compressor suction and discharge increased by ∼20%; and the heating capacity decreased by ∼30%. These results indicate that the T–H–T method can make an accurate decision under different frosting conditions. Cases 5a, 5b and Cases 6a, 6b were two groups of cases to compare the advantages of the T–H–T method against the conventional T–T method. Cases 5a and 5b were chosen for the non-frosting condition. It was found that the T–T method initiated the defrosting operation 31 times within 24 h. However, none of the defrosting operations was conducted for the T–H–T method. Cases 6a and 6b were chosen to compare these two methods under consecutive and variable frosting conditions. For the T–T method, 63% of the defrosting processes were found to be executed under conditions where defrosting was not necessary. However, for the T–H–T method, all the defrosting controls were found to be accurate and reasonable. These results indicated that the novel T–H–T method is suitable for the defrosting control of the ASHP, and has a more competitive performance than the conventional T–T method.     

一种基于FCOS神经网络的小建筑物目标检测方法北大核心

提出了一种基于FCOS神经网络的小建筑物目标检测算法,针对FCOS模型在特征提取阶段提取到的小建筑物目标特征较少问题,引入多尺度检测和可变形卷积方式,加强网络对小建筑物目标的特征提取能力,并通过改进后的SGE注意力机制降低特征图中的干扰噪声权重。改进后的网络可以提取到更多的小建筑物目标特征,对环境干扰噪声的鲁棒性更强。在自己搭建的数据集上进行了实验测试,结果表明,在相同环境下网络改进后建筑物的整体检测准确率提升了1.7%,其中对小建筑物目标提升了3.6%,减少了小建筑物目标漏检、误检的问题。     

“方变圆”变径筒状结构滑模施工技术

为解决塔式光热的核心构筑物吸热塔"方变圆"变径超高筒体结构施工难题,选用一套可变形的滑模平台系统,通过操作系统上可调千斤顶支座、门架横向液压千斤顶装置、多处可调节模板角度和收缩模板的丝杆等,使得滑模根据施工需求可在一定的范围内调节模板倾角、间距,并逐步完成收缩变形,其理论滑模允许偏角20°,最终高效完成异形结构施工。该滑模系统刚度大、承载及堆料能力强、空间大、机械化程度高,施工操作简单,安全性高,适应沙漠极端环境。全过程仅需使用一套滑模体系,就能完成方形段、方变圆的变形段及圆形段施工,大大提高了施工效率,为类似环境下相似结构的施工提供了一定的参考。     

Wind over complex terrain – Microscale modelling with two types of mesoscale winds at Nygårdsfjell

Nygårdsfjell, a complex terrain near Norwegian-Swedish border, is characterized by its significant wind resources. The feasibility of using mesoscale winds as input to microscale model is studied in this work. The main objective is to take into account the actual terrain effects on wind flow over complex terrain. First set of mesoscale winds are modelled with Weather Research and Forecasting (WRF) numerical tool whereas second set of mesoscale winds are taken from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) data system. WindSim, a computational fluid dynamics based numerical solver is used as microscale modelling tool. The results suggest that the performance of microscale model is largely dependent upon the quality of mesoscale winds as input. The proposed coupled models achieve improvements in wind speed modelling, especially during cold weather. WRF-WindSim coupling showed better results than MERRA-WindSim coupling in all three test cases, as root mean square error (RMSE) decreased by 70.9% for the February case, 61.5% for October and 14.4% for June case respectively. Raw mesoscale winds from the WRF model were also more correct than the mesoscale winds from MERRA data set when extracted directly at the wind turbine by decreasing the RMSE by 62.6% for the February case, 62.7% for October and 23.7% for June case respectively. The difference of RMSE values between the mesoscale winds directly at wind turbine versus the coupled meso-microscale model outputs are not conclusive enough to indicate any specific trend.