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Simulation research on the influence of eroded primary key strata on dynamic strata pressure of shallow coal seams in gully terrain 被引量:13
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作者 Zhang Zhiqiang Xu Jialin +1 位作者 Zhu Weibing Shan Zhenjun 《International Journal of Mining Science and Technology》 2012年第1期51-55,共5页
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 experimental me... 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 experimental method to thoroughly study the influence of eroded overlying primary key strata (PKS) in the gully terrain on DSP of shallow coal seams in this paper. The result show that when mining activities took place in the uphill section of shallow coal seams in gully terrain and the PKS were eroded, the blocks could not form stable bond-beam structures since the horizontal force of PKS blocks in adjacent sloping surfaces were relatively small. The sliding instability of blocks caused rapid increase of the load on the sub-key strata (SKS) blocks, which resulted into coal slide and roof fall as well as sharp drop of active columns. This led to DSP phenomenon. When the PKS blocks were intact, there was no DSP phenomenon to enable blocks provide certain horizontal force to maintain stable bond-beam structure. The simulation results were verified by the mining practices of working face 21306 crossing the gully terrain in the Huojitu Coal Mine. 展开更多
关键词 strata (KS) Being eroded Gully terrain Shallow coal seam dynamic strata pressure
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Automatic target tracking on multi-resolution terrain 被引量:2
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作者 WAN Ming ZHANG Wei +1 位作者 MURRAY Marie O. KAUFMAN Ariet 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第7期1275-1281,共7页
We propose a high-performance path planning algorithm for automatic target tracking in the applications of real-time simulation and visualization of large-scale terrain datasets, with a large number of moving objects ... We propose a high-performance path planning algorithm for automatic target tracking in the applications of real-time simulation and visualization of large-scale terrain datasets, with a large number of moving objects (such as vehicles) tracking multiple moving targets. By using a modified Dijkstra's algorithm, an optimal path between each vehicle-target pair over a weighted grid-presented terrain is computed and updated to eliminate the problem of local minima and losing of tracking. Then, a dynamic path re-planning strategy using multi-resolution representation of a dynamic updating region is proposed to achieve high-performance by trading-off precision for efficiency, while guaranteeing accuracy. Primary experimental results showed that our algorithm successfully achieved l0 to 96 frames per second interactive path-replanning rates during a terrain simulation scenario with 10 to 100 vehicles and multiple moving targets. 展开更多
关键词 Target tracking Path planning Dijkstra's algorithm Voxel-based modeling multi-resolution terrain Real-timevisualization and simulation
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Dynamic Analysis of the Seafloor Pilot Miner Based on Single-Body Vehicle Model and Discretized Track-Terrain Interaction Model 被引量:5
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作者 戴瑜 刘少军 李力 《China Ocean Engineering》 SCIE EI 2010年第1期145-160,共16页
In order to achieve the complex dynamic analysis of the self-propelled seafloor pilot miner moving on the seafloor of extremely cohesive soft soil and further to make it possible to integrate the miner system with som... In order to achieve the complex dynamic analysis of the self-propelled seafloor pilot miner moving on the seafloor of extremely cohesive soft soil and further to make it possible to integrate the miner system with some subsystems to form the complete integrated deep ocean mining pilot system and perform dynamic analysis, a new method for the dynamic modeling and analysis of the miner is proposed and developed in this paper, resulting in a simplified 3D single-body vehicle model with three translational and three rotational degrees of freedom, while the track-terrain interaction model is built by partitioning the track-terrain interface into discrete elements with parameterized force dements built on the theory of terramechanics acting on each discrete dement. To evaluate and verify the correctness and effectiveness of this new modeling and analysis method, typical comparative studies with regard to computational efficiency and solution accuracy are carried out between the traditional modeling method of building the tracked vehicle as a multi-body model and the new modeling method. In full consideration of the particMar structure design of the pilot miner, the special characteristics of the seafioor soil and the hydrodynamic force of near-seafloor currnt, the dynamic simulation analysis of the miner is performed and discussed, which can provide useful guidance and reference for the practical miner system in design and operation. This new method can not only realize the rapid dynamic simulation analysis of the miner but also make possible the integration and rapid dynamic analysis of the complete integrated deep ocean mining pilot system in further researches. 展开更多
关键词 deep-ocean mining system self-propelled seafloor pilot miner single-body model multi-body model discretized track-terrain interaction model dynamic analysis
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Dynamic Terrain Visualization Based on ROAM and OGRE 被引量:2
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作者 FU Hui WANG Quanmin 《系统仿真技术》 2009年第1期55-59,76,共6页
Terrain Visualization is an important part of visualization systems of battlefield,and the visualization of dynamic terrain is also important for dynamic battle environment.In this paper,special attention has been pai... Terrain Visualization is an important part of visualization systems of battlefield,and the visualization of dynamic terrain is also important for dynamic battle environment.In this paper,special attention has been paid on real-time optimally adapting meshes (ROAM) algorithm,which is a candidate for dynamic terrain,and its mesh representation,mesh continuity algorithm and error metrics are discussed.The DEXTER-ROAM algorithm is discussed and analyzed.By revising the mesh representation of ROAM,a dynamic ROAM algorithm based on partial-regular grid is established.By introducing transition region,mesh discontinuity of dynamic partial-regular grid is resolved.Error metric blocks are removed for computation complexity and culling blocks are introduced to accelerate view frustum culling.The algorithm is implemented in a 3D rendering engine called OGRE.In the end,an example of dynamic crater is given to examine the dynamic ROAM algorithm. 展开更多
关键词 地形可视化系统 自动化技术 网格 计算方法
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Computational fluid dynamics evaluation of the effect of different city designs on the wind environment of a downwind natural heritage site 被引量:4
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作者 BenLi LIU JianJun QU +2 位作者 QingHe NIU JunZhan WANG KeCun ZHANG 《Journal of Arid Land》 SCIE CSCD 2014年第1期69-79,共11页
Disturbance in wind regime and sand erosion deposition balance may lead to burial and eventual vanishing of a site.This study conducted 3D computational fluid dynamics(CFD)simulations to evaluate the effect of a propo... Disturbance in wind regime and sand erosion deposition balance may lead to burial and eventual vanishing of a site.This study conducted 3D computational fluid dynamics(CFD)simulations to evaluate the effect of a proposed city design on the wind environment of the Crescent Spring,a downwind natural heritage site located in Dunhuang,Northwestern China.Satellite terrain data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)Digital Elevation Model(DEM)were used to construct the solid surface model.Steady-state Reynolds Averaged Navier-Stokes equations(RANS)with shear stress transport(SST)k-ωturbulence model were then applied to solve the flow field problems.Land-use changes were modeled implicitly by dividing the underlying surface into different areas and by applying corresponding aerodynamic roughness lengths.Simulations were performed by using cases with different city areas and building heights.Results show that the selected model could capture the surface roughness changes and could adjust wind profile over a large area.Wind profiles varied over the greenfield to the north and over the Gobi land to the east of the spring.Therefore,different wind speed reduction effects were observed from various city construction scenarios.The current city design would lead to about 2 m/s of wind speed reduction at the downwind city edge and about 1 m/s of wind speed reduction at the north of the spring at 35-m height.Reducing the city height in the north greenfield area could efficiently eliminate the negative effects of wind spee.By contrast,restricting the city area worked better in the eastern Gobi area compared with other parts of the study area.Wind speed reduction in areas near the spring could be limited to 0.1 m/s by combining these two abatement strategies.The CFD method could be applied to simulate the wind environment affected by other land-use changes over a large terrain. 展开更多
关键词 computational fluid dynamics wind environment wind profile large terrain Crescent Spring
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A 3D Nonhydrostatic Compressible Atmospheric Dynamic Core by Multi-moment Constrained Finite Volume Method 被引量:2
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作者 Qingchang QIN Xueshun SHEN +3 位作者 Chungang CHEN Feng XIAO Yongjiu DAI Xingliang LI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2019年第10期1129-1142,共14页
A 3D compressible nonhydrostatic dynamic core based on a three-point multi-moment constrained finite-volume (MCV) method is developed by extending the previous 2D nonhydrostatic atmospheric dynamics to 3D on a terrain... A 3D compressible nonhydrostatic dynamic core based on a three-point multi-moment constrained finite-volume (MCV) method is developed by extending the previous 2D nonhydrostatic atmospheric dynamics to 3D on a terrainfollowing grid. The MCV algorithm defines two types of moments: the point-wise value (PV) and the volume-integrated average (VIA). The unknowns (PV values) are defined at the solution points within each cell and are updated through the time evolution formulations derived from the governing equations. Rigorous numerical conservation is ensured by a constraint on the VIA moment through the flux form formulation. The 3D atmospheric dynamic core reported in this paper is based on a three-point MCV method and has some advantages in comparison with other existing methods, such as uniform third-order accuracy, a compact stencil, and algorithmic simplicity. To check the performance of the 3D nonhydrostatic dynamic core, various benchmark test cases are performed. All the numerical results show that the present dynamic core is very competitive when compared to other existing advanced models, and thus lays the foundation for further developing global atmospheric models in the near future. 展开更多
关键词 multi-moment CONSTRAINED FINITE-VOLUME method NONHYDROSTATIC dynamic core topography height-based terrain-following coordinate
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An Integrated Dynamic Model of Ocean Mining System and Fast Simulation of Its Longitudinal Reciprocating Motion 被引量:3
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作者 戴瑜 刘少军 《China Ocean Engineering》 SCIE EI CSCD 2013年第2期231-244,共14页
An integrated dynamic model of China's deep ocean mining system is developed and the fast simulation analysis of its longitudinal reciprocating motion operation processes is achieved. The seafloor tracked miner is bu... An integrated dynamic model of China's deep ocean mining system is developed and the fast simulation analysis of its longitudinal reciprocating motion operation processes is achieved. The seafloor tracked miner is built as a three-dimensional single-body model with six-degree-of-freedom. The track-terrain interaction is modeled by partitioning the track-terrain interface into a certain number of mesh elements with three mutually perpendicular forces, including the normal force, the longitudinal shear force and the lateral shear force, acting on the center point of each mesh element. The hydrodynamic force of the miner is considered and applied. By considering the operational safety and collection efficiency, two new mining paths for the miner on the seafloor are proposed, which can be simulated with the established single-body dynamic model of the miner. The pipeline subsystem is built as a three-dimensional multi-body discrete element model, which is divided into rigid elements linked by flexible connectors. The flexible connector without mass is represented by six spring-damper elements. The external hydrodynamic forces of the ocean current from the longitudinal and lateral directions are both considered and modeled based on the Morison formula and applied to the mass center of each corresponding discrete rigid element. The mining ship is simplified and represented by a general kinematic point, whose heave motion induced by the ocean waves and the longitudinal and lateral towing motions are considered and applied. By integrating the single-body dynamic model of the miner and the multi-body discrete element dynamic model of the pipeline, and defining the kinematic equations of the mining ship, the integrated dynamic model of the total deep ocean mining system is formed. The longitudinal reciprocating motion operation modes of the total mining system, which combine the active straight-line and turning motions of the miner and the ship, and the passive towed motions of the pipeline, are proposed and simulated with the developed 3D dynamic model. Some critical simulation results are obtained and analyzed, such as the motion trajectories of key subsystems, the velocities of the buoyancy modules and the interaction forces between subsystems, which in a way can provide important theoretical basis and useful technical reference for the practical deep ocean mining system analysis, operation and control. 展开更多
关键词 deep ocean mining system single-body model track-terrain interaction model discrete element model longitudinal reciprocating motion operation mode dynamic simulation analysis
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Computational fluid dynamics simulation of gas dispersion in complex facilities using Kit Fox field experiments:Validation and statistical evaluation
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作者 Narjes Hemati Alam Eslam Kashi Razieh Habibpour 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2022年第4期412-423,共12页
Gas release and its dispersion is a major concern in chemical industries.In order to manage and mitigate the risk of gas dispersion and its consequences,it is necessary to predict gas dispersion behavior and its conce... Gas release and its dispersion is a major concern in chemical industries.In order to manage and mitigate the risk of gas dispersion and its consequences,it is necessary to predict gas dispersion behavior and its concentration at various locations upon emission.Therefore,models and commercial packages such as Phast and ALOHA have been developed.Computational fluid dynamics(CFD)can be a useful tool to simulate gas dispersion in complex areas and conditions.The validation of the models requires the employment of the experimental data from filed and wind tunnel experiments.It appears that the use of the experimental data to validate the CFD method that only includes certain monitor points and not the entire domain can lead to unreliable results for the intended areas of concern.In this work,some of the trials of the Kit Fox field experiment,which provided a wide-range database for gas dispersion,were simulated by CFD.Various scenarios were considered with different mesh sizes,physical conditions,and types of release.The results of the simulations were surveyed in the whole domain.The data matching each scenario was varied by the influence of the dominant displacement force(wind or diffusivity).Furthermore,the statistical parameters suggested for the heavy gas dispersion showed a dependency on the lower band of gas concentration.Therefore,they should be used with precaution.Finally,the results and computation cost of the simulation could be affected by the chosen scenario,the location of the intended points,and the release type. 展开更多
关键词 Gas dispersion simulation Computational fluid dynamics Complex terrain Obstructed flow
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沙漠履带式运输车通过性仿真与试验
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作者 王宝昌 孙术发 +1 位作者 张嘉仪 刘晋浩 《森林工程》 北大核心 2024年第4期186-195,共10页
为提高沙漠地区车辆运输车能力,通过对沙漠土壤参数和履带车辆在松软地面通过性理论的分析,设计一种配备三角履带板的LY352J型沙漠履带式运输车。该车能够进行人员物资运输、车辆牵引、绞盘牵引作业,主要由三角履带板、绞盘和驾驶室等... 为提高沙漠地区车辆运输车能力,通过对沙漠土壤参数和履带车辆在松软地面通过性理论的分析,设计一种配备三角履带板的LY352J型沙漠履带式运输车。该车能够进行人员物资运输、车辆牵引、绞盘牵引作业,主要由三角履带板、绞盘和驾驶室等关键部位组成。通过理论分析和计算,确定各关键部件参数及沙漠履带式运输车在沙漠松软地面下的牵引通过性,应用Creo软件建立该履带车辆的虚拟样机模型,并采用RecurDyn(Recursive Dynamic)动力学仿真软件对车辆履带的最佳张紧力选择、直行、爬坡、转弯进行模拟仿真。结果显示,车重45%的条件下履带最佳张紧力为26.46 kN,能够保证车辆运行平稳且各项性能良好;上坡仿真得到的最大坡度为30°;转向动力学仿真中,车辆在路面上的转向稳定性较优,但在转弯时车辆容易失稳,会出现横向倾斜。最后在试验场地对试验样机进行直行、纵向爬坡和转向试验,验证该车型在沙漠地形实际行走时具有良好通过性能,能够克服轮式运输车在沙地沉陷的弊端,可满足现阶段沙漠地形运输作业的需求。 展开更多
关键词 履带底盘 沙漠地形 通过性 多体动力学分析
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利用前视和测高声呐的UUV地形跟踪动态路径生成方法
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作者 陈涛 万首 《水下无人系统学报》 2024年第2期304-310,共7页
保持对海底地形的定高跟踪航行是无人水下航行器(UUV)执行海洋勘测和水下目标搜索任务时常采用的一种运动形式,其核心是UUV如何对未知起伏的海底地形进行实时探测,并基于探测信息在线、动态地生成跟踪路径,以实现对地形的定高跟踪航行,... 保持对海底地形的定高跟踪航行是无人水下航行器(UUV)执行海洋勘测和水下目标搜索任务时常采用的一种运动形式,其核心是UUV如何对未知起伏的海底地形进行实时探测,并基于探测信息在线、动态地生成跟踪路径,以实现对地形的定高跟踪航行,同时避免与地形发生碰撞。针对上述问题,提出了一种基于前视声呐探测地形信息、基于多项式拟合动态生成跟踪路径的方法。首先,UUV利用前视声呐对海底地形进行实时探测,对获得的地形探测数据进行仿射处理后,得到具有离散特性的定高仿射数据。然后,采用基于最小二乘准则的三次多项式方法对仿射数据进行拟合,生成基于多项式函数描述的UUV地形跟踪航行路径。最后,设计了一种包含声呐探测、数据仿射、路径生成和跟踪控制的动态执行框架,实现UUV的实时地形跟踪航行任务。文中所提出的跟踪路径生成和动态执行框架通过对典型的海底“上坡”地形和“山地”地形跟踪的仿真验证,证明了其有效性和可行性。 展开更多
关键词 无人水下航行器 海底地形跟踪 动态路径 前视声呐 多项式拟合
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铁路线路与地形三维模型实时动态融合方法研究 被引量:1
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作者 温绍成 蒲浩 +3 位作者 宋陶然 李伟 相诗尧 张涛 《铁道科学与工程学报》 EI CAS CSCD 北大核心 2024年第3期1004-1014,共11页
铁路线路与地形三维模型的融合是实现铁路线路三维正向设计的瓶颈之一。线路设计过程中,需要实时更新三维场景。现有的静态融合方法会修改原始的地形数据,且计算量大,耗时过长,无法满足动态交互式设计的需求。对此,提出一种铁路线路与... 铁路线路与地形三维模型的融合是实现铁路线路三维正向设计的瓶颈之一。线路设计过程中,需要实时更新三维场景。现有的静态融合方法会修改原始的地形数据,且计算量大,耗时过长,无法满足动态交互式设计的需求。对此,提出一种铁路线路与地形三维模型实时动态融合方法。基于铁路三维场景,在每帧显示前动态提取视相关地形瓦片模型和线路三维模型,在内存中基于线程池并行对地形瓦片裁剪,实现二者的实时融合,并构建缓存队列,重复利用融合结果。为了提升单块地形瓦片和线路三维模型的融合效率,提出了“超挖-回填”的融合思想。借助高效的三角形空间网格索引,快速删除融合边界内及相交网格涉及到的三角形,虽然“超挖”部分三角形,但避免了繁杂的三角形定位、调整计算。依据超挖三角形外边界和融合边界构建“回填”区域,再采用剪耳法对“回填”区域重构三角网,实现铁路线路与地形三维模型的无缝融合。基于该方法开发了铁路线路三维设计系统,对一条104.9 km铁路案例进行了实验,结果表明:其显示帧率可以保持在35~45 fps,且能够实时更新三维场景。相较于传统的静态融合方法,该方法将长时间的全局模型融合转化为帧前的局部视相关动态融合,减少了线路方案修改时更新的融合数据量及计算量,从而满足了动态交互式设计的需求,提升了三维正向设计的效率。 展开更多
关键词 铁路线路 三维建模 动态融合 视相关 地形裁剪
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复杂地形下轮腿复合机动平台动态运动控制
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作者 任晓磊 刘辉 +4 位作者 韩立金 陈前 聂士达 谢景硕 崔山 《兵工学报》 EI CAS CSCD 北大核心 2024年第9期2993-3003,共11页
复杂地形环境下质心参考轨迹的动态精确跟踪是保障轮腿复合机动平台稳定执行各项任务的关键。为提升平台的地形适应能力与位姿跟踪能力,提出一种动态运动控制策略。综合地形因素,建立包含车轮动力学的单刚体动力学模型,并通过近似简化... 复杂地形环境下质心参考轨迹的动态精确跟踪是保障轮腿复合机动平台稳定执行各项任务的关键。为提升平台的地形适应能力与位姿跟踪能力,提出一种动态运动控制策略。综合地形因素,建立包含车轮动力学的单刚体动力学模型,并通过近似简化将系统动力学模型转化为状态空间方程的标准形式。考虑车轮与腿部耦合运动,提出一种基于前馈力矩与反馈力矩的混合运动控制方法。通过二次规划算法求解最优地面反作用力,利用雅克比矩阵将作用力映射至关节以获取前馈力矩。为避免由环境引起的外部扰动造成系统无法在较短时间内完成优化计算,引入关节力矩反馈控制及时修正位姿跟踪误差,使系统能够快速准确地响应外部扰动,有效提高系统的鲁棒性和稳定性。仿真结果表明,新方法可有效提升平台在复杂地形下位姿动态跟踪精度,保障平台平稳运行,为复杂地形下轮腿复合机动平台的工程应用提供有力支撑。 展开更多
关键词 轮腿复合机动平台 复杂地形 单刚体动力学模型 混合运动控制
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π形山脉主山脊线风速加速效应研究
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作者 鲍旭明 楼文娟 +3 位作者 廖孙策 林晨琦 陈科技 卞荣 《湖南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第1期170-179,共10页
为研究真实地形的加速效应,提取真实地形的几何特征建立理想简化地形,提出一种π形山脉模型.采用CFD数值模拟研究顺子山脉风向下子山脉间距、长度及坡度对主山脊线加速效应的影响,结合地形特征比较π形山脉与三维余弦山脉的主山脊线加... 为研究真实地形的加速效应,提取真实地形的几何特征建立理想简化地形,提出一种π形山脉模型.采用CFD数值模拟研究顺子山脉风向下子山脉间距、长度及坡度对主山脊线加速效应的影响,结合地形特征比较π形山脉与三维余弦山脉的主山脊线加速比差异,在后者基础上获得π形山脉主山脊线特征点的风速加速比简化计算公式,并通过一处真实π形山脉加以验证.结果表明:π形山脉主山脊线中点的加速比受子山脉间距、长度影响较大,而山脊线交点的加速比受子山脉长度、坡度影响较大;与三维余弦山脉相比,π形山脉主山脊线加速比在山脊线端部相同,但整体偏小,尤其受子山脉遮挡的部分显著偏小,超过离地70 m高度后差异基本消失;通过与真实π形山脉的风场比较,发现简化地形和简化计算公式能较好反映真实地形主山脊线特征点的加速效应. 展开更多
关键词 山脉 简化地形 加速比 计算流体力学(CFD) 数值模拟
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复杂地形风电场微观选址的GA-PSO混合算法研究
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作者 胡伟成 杨庆山 +3 位作者 聂彪 陈华鹏 闫渤文 许紫刚 《太阳能学报》 EI CAS CSCD 北大核心 2024年第5期118-125,共8页
提出一种结合改进遗传算法(GA)和粒子群算法(PSO)的GA-PSO混合算法对复杂地形的风力机排布方案进行优化。以湖南省某实际复杂地形为对象,开展风场全风向数值模拟,结合长期观测风资料评估区域的潜在风能分布,提出考虑网格预处理、时变变... 提出一种结合改进遗传算法(GA)和粒子群算法(PSO)的GA-PSO混合算法对复杂地形的风力机排布方案进行优化。以湖南省某实际复杂地形为对象,开展风场全风向数值模拟,结合长期观测风资料评估区域的潜在风能分布,提出考虑网格预处理、时变变异率、唯一化和并行化的改进GA(IGA)对风力机排布方案进行优化,在此基础上利用PSO算法进行进一步优化,并针对尾流模型和目标函数对优化结果的影响进行不确定性分析。结果表明,在复杂地形风电场微观选址方面,所提GA-PSO算法比贪婪算法、GA、IGA分别改善16.4%、12.9%和5.1%。 展开更多
关键词 风电场 遗传算法 粒子群算法 复杂地形 微观选址 计算流体动力学
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复杂地形地质条件下桥梁桩基的动态设计
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作者 龙培 《公路交通技术》 2024年第3期55-61,共7页
在山区桥梁桩基的实施过程中,因实际地形地质条件复杂,桩基常需动态调整设计。为了解决山区高速公路桥隧比高,需动态调整桩基多,逐桩逐项调整效率低,影响施工进度的问题,提出了一种新的桩基动态设计流程,并以巫镇路茶园子大桥1#桥墩为例... 在山区桥梁桩基的实施过程中,因实际地形地质条件复杂,桩基常需动态调整设计。为了解决山区高速公路桥隧比高,需动态调整桩基多,逐桩逐项调整效率低,影响施工进度的问题,提出了一种新的桩基动态设计流程,并以巫镇路茶园子大桥1#桥墩为例,应用动态设计流程的思路,论证了在复杂地形地质条件下桥梁桩基动态设计流程的实用性。工程实践表明:该流程可确保结构安全及动态设计效率。 展开更多
关键词 复杂地形地质 桥梁桩基 动态设计 结构安全 设计效率
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江西和福建省植被覆盖时空特征及其地形梯度效应
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作者 林莹冰 王小军 +3 位作者 全明英 林杜锐 卢毅 刘光旭 《水土保持研究》 CSCD 北大核心 2024年第1期290-300,共11页
[目的]探讨华南地区植被覆盖时空特征,为生态系统调查与保护提供参考。[方法]以江西和福建省为例,将1998年、2005年、2010年、2015年、2019年5年的植被覆盖由低到极高划分为6个等级,使用土地利用研究中的动态度、转移等思路分析植被覆... [目的]探讨华南地区植被覆盖时空特征,为生态系统调查与保护提供参考。[方法]以江西和福建省为例,将1998年、2005年、2010年、2015年、2019年5年的植被覆盖由低到极高划分为6个等级,使用土地利用研究中的动态度、转移等思路分析植被覆盖时空特征,并探讨其地形梯度效应。[结果](1)江西和福建植被覆盖以高和极高覆盖为主(78.47%~89.8%),尤其是在内陆山地丘陵区,而沿江、沿海等人口密集的城市区相对较低、面积较小;1998—2019年该区植被覆盖较好且变化的整体趋势仍是增加;最显著变化发生在2010—2015年由高覆盖转移为极高覆盖。(2)地形梯度指数显示,中等植被覆盖及以下主要分布在海拔低于200 m、坡度小于6°、地形位小于0.48的1~2级地形梯度区;较高覆盖及以上较为分散的分布在各地形梯度内,且随着覆盖度增加有向海拔高于200 m、坡度大于6°、地形位大于0.48的3~5级地形梯度区分布趋势。(3)在植被覆盖不变或改善类中,低覆盖转移主要发生在1级地形梯度,较低覆盖和中等覆盖转移主要发生在1~3级地形梯度区,较高覆盖及以上的转移在5类地形梯度均有发生且相对分散;在植被覆盖恶化类中,中等覆盖及以下的转移多发生在1~3级地形梯度区,较高覆盖及以上的转移在5类地形梯度区多有发生且相对分散;转移等级跨度较大的情况多发生在较低等级的地形梯度区。[结论]研究区植被覆盖率较高,植被覆盖变化存在时空差异,生态系统调查与保护需要考虑不同地形梯度下的影响因素。 展开更多
关键词 植被覆盖 时空特征 地形梯度 动态度 弦图 华南
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四轮全地形车匹配CVT变速箱动力性仿真研究
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作者 孙威 《汽车实用技术》 2024年第13期60-64,共5页
为了论证一款钢带式无级变速器(CVT)匹配四轮全地形车的可行性,文章根据全地形车的动力总成结构,基于MATLAB建立了钢带式CVT匹配四轮全地形车的Simulink模型。使用该模型对整车的动力性进行仿真,通过对其使用工况的研究和最高车速、加... 为了论证一款钢带式无级变速器(CVT)匹配四轮全地形车的可行性,文章根据全地形车的动力总成结构,基于MATLAB建立了钢带式CVT匹配四轮全地形车的Simulink模型。使用该模型对整车的动力性进行仿真,通过对其使用工况的研究和最高车速、加速时间、最大爬坡度和最大牵引力的仿真计算,与客户设定的目标进行对比,为项目的可行性分析提供前期的论证依据。仿真结果显示,此款钢带式CVT能够很好满足客户的性能目标,同时验证了此模型能够很好的完成固定工况的仿真计算。 展开更多
关键词 钢带式CVT 四轮全地形车 SIMULINK模型 动力性
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Effect of the off-road terrains on the ride comfort of construction vehicles 被引量:1
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作者 Nguyen Van Liem Zhang Jianrun +1 位作者 Jiao Renqiang Du Xiaofei 《Journal of Southeast University(English Edition)》 EI CAS 2019年第2期191-197,共7页
In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based o... In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based on Matlab/Simulink software.The weighted root mean square(RMS)acceleration responses and the power spectral density(PSD)acceleration responses of the driver s seat heave,the pitch and roll angle of the cab in the low-frequency region are chosen as objective functions under different operation conditions of the vehicle.The results show that the impact of off-road terrains on the driver s ride comfort and health is clear under various conditions of deformable terrains and range of vehicle velocities.In particular,the driver s ride comfort is greatly affected by a soil terrain while the comfortable shake of the driver is strongly affected by a sand terrain.In addition,when the vehicle travels on a poor soil terrain in the frequency range below 4 Hz,more resonance peaks of acceleration PSD responses occurred than that on a rigid road of ISO 2631-1 level C.Thus,the driver s health is significantly affected by the deformable terrain in a low-frequency range. 展开更多
关键词 construction vehicles vehicle dynamic model off-road terrains ride comfort
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Application of FLUENT on fine-scale simulation of wind field over complex terrain 被引量:2
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作者 Lei Li LiJie Zhang +3 位作者 Ning Zhang Fei Hu Yin Jiang WeiMei Jiang 《Research in Cold and Arid Regions》 2010年第5期411-418,共8页
The state-of-art Computational Fluid Dynamics (CFD) codes FLUENT is applied in a fine-scale simulation of the wind field over a complex terrain. Several numerical tests are performed to validate the capability of FL... The state-of-art Computational Fluid Dynamics (CFD) codes FLUENT is applied in a fine-scale simulation of the wind field over a complex terrain. Several numerical tests are performed to validate the capability of FLUENT on describing the wind field details over a complex terrain. The results of the numerical tests show that FLUENT can simulate the wind field over extremely complex terrain, which cannot be simulated by mesoscale models. The reason why FLUENT can cope with extremely complex terrain, which can not be coped with by mesoscale models, relies on some particular techniques adopted by FLUENT, such as computer-aided design (CAD) technique, unstructured grid technique and finite volume method. Compared with mesoscale models, FLUENT can describe terrain in much more accurate details and can provide wind simulation results with higher resolution and more accuracy. 展开更多
关键词 FLUENT Computational Fluid dynamics (CFD) complex terrain wind field fine-scale simulation
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Large-Scale Terrain Simplification and Visualization Based on TIN 被引量:3
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作者 KANG Lai, WU Ling-da, YANG Bing, SONG Han-chen (College of Information Systems & Management, National University of Defense Technology, Changsha 410073, China) 《Computer Aided Drafting,Design and Manufacturing》 2008年第2期1-8,共8页
In the preprocessing phase, the global terrain model is partitioned into blocks with their feature points being picked out to generate TIN model for each terrain block, then the multi-resolution models of terrain orga... In the preprocessing phase, the global terrain model is partitioned into blocks with their feature points being picked out to generate TIN model for each terrain block, then the multi-resolution models of terrain organized in the form of quad-tree is created bottom-up. Cracks between terrain blocks are avoided by inserting vertices to form common boundaries. At run-time, a view-dependent LOD algorithm is used to control the loading and unloading of the proper blocks by an additional synchronous thread. To eliminate the artifacts created by LOD transitions, geomorphing is used in real-time. These rendering strategies increase the throughput of GPU and avoid imbalance of load among CPU, GPU and Disk I/O. Experimental results show that the system can perform visually smooth rendering of large-scale terrain scenes with fine quality at an average rate of 80 fps. 展开更多
关键词 real-time rendering 3D terrain multi-resolution triangulated irregular network quad-tree
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