基于多分辨率数据源镶嵌的大规模地形实时绘制算法

针对不同分辨率的测量地形数据源,提出了镶嵌四叉树模型,用以实现对多分辨率数据源的镶嵌,以及与细节层次(LOD)算法的融合.设计了基于此模型的批LOD算法,给出了相关公式,并设计了一种从CPU到GPU的渐进LOD数据传输方法.分析了镶嵌四叉树的场景浏览模式,设计了基于此模型的双向两级外存数据调度算法,通过水平、高度两个方向的预测和两级数据预取实现数据页的动态更新,实现了三维地形场景的快速构建和实时浏览.实验表明,该算法能够快速处理大规模多分辨率数据源并且能够充分发挥CPU、GPU与I/O的效率,从而在有限环境下进行快速实时绘制.     

面向离散地形的欠驱动双足机器人平衡控制方法

欠驱动双足机器人在行走中为保持自身的平衡, 双脚需要不间断运动. 但在仅有特定立足点的离散地形上很难实现调整后的落脚点, 从而导致欠驱动双足机器人在复杂环境中的适应能力下降. 提出了基于虚拟约束(Virtual constraint, VC)的变步长调节与控制方法, 根据欠驱动双足机器人当前状态与参考落脚点设计了非时变尺度缩放因子, 能够实时重构适应当前环境的步态轨迹; 同时构建了全身动力学模型, 采用反馈线性化的模型预测控制 (Model predictive control, MPC) 滚动优化产生力矩控制量, 实现准确的轨迹跟踪控制. 最终进行了欠驱动双足机器人的随机离散地形稳定行走的仿真实验, 验证了所提方法的有效性与鲁棒性.     

基于相对特征的越野地形可通行性分析

自主地面车在越野环境下导航面临最困难的问题之一是对地形的理解,分析感知到的越野地形,作适合于自主车导航的可通行性分析。本文提出了越野高程地形的相对不变性概念,并利用这种性质提取出在一定尺度范围内地形具有的相对不变特征,如地形坡度、起伏度和粗糙度,最后基于模糊规则组合各特征对地形的可通行性进行评估。自主车越野导航实验表明,本文算法稳定有效,能满足自主地面车越野导航的需要。     

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...     

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。     

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.     

变形轮侦察机器人的控制系统设计

为提高机器人适应复杂地面环境的能力,车轮采用可变形为三爪的结构,可根据不同的路面,选择轮式移动和爪式爬行两种步态,实现现场侦察。该机器人采用上下两级的控制策略,以Lab view软件进行上级监视、操控界面开发,下级选用功能强大的STM32芯片作为车载主控制器,MSP430单片机作为协控制器,应用RS－485总线组成分布式控制系统。有效的实现了机器人的远程控制和信息传递。     

某输电线路工程滑坡特征分析与评价

某750 kV输电线路部分段走径于天水地区滑坡区段,区域滑坡类型主要以黄土滑坡和黄土-泥岩接触面滑坡为主,最易滑坡坡度在20°~39°之间,占全部滑坡的72.3%;滑坡的形成原因主要有地质构造、地震作用、岩性特征、地形地貌、水文气象条件和人类活动等多个方面;通过分析地区滑坡特征,采取滑带土进行室内试验,分析滑带土物理力学性质,进行典型滑坡的稳定性分析与评价。