排序方式： 共有49条查询结果，搜索用时 15 毫秒
31.
提出了一种层次包围盒(BVH)方法,以加速基于GPU的3D纹理体绘制.该方法首先利用GPU的片元着色程序实现了后分类3D纹理体绘制;然后设定高度逐层对体教据进行分解,为每个生成的子体数据建立相应的包围盒,并用对应层次包围盒树的结点保存相关信息;最后遍历层次包围盒树,读取层次包围盒树的结点信息以判断对应子体数据是否被绘制或跳过,从而实现空间跳跃,加速3D纹理体绘制.实验结果表明,本文方法与基于GPU的3D纹理体绘制算法相结合,能取得良好的加速效果. 相似文献
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Study on Failure Mechanism and Bearing Capacity of Three-Dimensional Rectangular Footing Subjected to Combined Loading 总被引：2，自引：0，他引：2
This paper presents two kinematic failure mechanisms of threc-dimensional rectangular footing resting on homogeneous undrained clay foundation under uniaxial vertical loading and uniaxial moment loading. The failure mechanism under vertical loading comprises a plane strain Prandti-type mechanism over the central part of the longer side, and the size of the mechanism gradually reduces at the ends of the longer side and over the shorter side as the corner of rectangular footing is being approached where the direction of soil motion remains normal to each corresponding side respectively. The failure mechanism under moment loading comprises a plane strain scoop sliding mechanism over the central part of the longer side, and the radius of scoop sliding mechanism increases linearly at the ends of the longer side. On the basis of the kinematic failure mechanisms mentioned above, the vertical ultimate bearing capacity and the ultimate bearing capacity against moment or moment ultimate bearing capacity are obtained by use of upper bound limit analysis theory. At the same time, numerical analysis results, Skempton＇ s results and Salgado et al. ＇s results are compared with this upper bound solution. It shows that the presented failure mechanisms and plastic limit analysis predictions are validated. In order to investigate the behaviors of undrained clay foundation beneath the rectangular footing subjected to the combined loadings, numerical analysis is adopted by virtue of the general-purpose FEM software ABAQUS, where the clay is assumed to obey the Mohr-Coulomb yielding criterion. The failure envelope and the ultimate bearing capacity are achieved by the numerical analysis results with the varying aspect ratios from length L to breadth B of the rectangular footing. The failure mechanisms of rectangular footing which are subjected to the combined vertical loading V and horizontal loading H （Vertical loading V and moment loading M, and horizontal loading H and moment loading M respectively are observed in the finite e 相似文献
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针对现有微地图（WeMaps）推荐算法未充分挖掘用户与微地图特征,推荐结果准确率较低的问题,提出融合特征交叉与用户历史行为序列的微地图推荐算法。首先,在用户与地图特征交叉过程中通过引入跳跃连接和多头自注意力机制,让不同特征组合能够自动获得权重,并通过在多个子空间下进行特征交叉获得了更丰富的特征组合信息。其次,在用户历史行为序列中引入了交叉注意力机制,捕捉与候选地图相关的兴趣点。最后,融合特征交叉和用户行为序列模块的输出,获得了综合多个维度的推荐结果。在公开数据集Criteo和自制微地图（WeMaps）数据集上的对数损失值分别为0.446 1、0.379 7,受试者操作特征曲线下面积值（Area Under the ROC Curve,AUC）分别为0.805 2、0.788 3。相较于本文对比实验中的二阶特征交叉模型,损失值分别降低了1.7%、14.2%,AUC值提高了0.8%、0.4%。相较于本文对比实验中的高阶特征交叉模型,损失值平均降低了1.3%、2.6%,AUC值平均提高了0.6%,0.2%。较低的损失值和较高的AUC值说明模型进行预测时具有较高的准确性和较好的分类能力。实验结... 相似文献
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研究一类时滞不确定随机Markovian跳变系统的滑模控制问题。首先,给出了由有限维状态空间中齐次Mar-kovian过程产生的跳跃参数,利用次可达的概念,给出了该系统的状态轨线逼近确定滑模面的条件;其次,设计了滑模变结构控制器,保证系统运动到达滑模是次可达的,并且给出了系统滑动运动为均方渐近稳定的充分条件;最后,通过仿真例子说明了本文方法的可行性与有效性。 相似文献
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基于TIGGE资料中欧洲中期天气预报中心(ECMWF)、美国国家环境预报中心(NCEP)和中国气象局(CMA)3个集合预报系统的地面气温集合预报资料,运用跳跃指数研究了3个集合预报系统中东亚地面气温的控制预报及集合平均预报的不一致性。结果表明,各个集合预报系统地面气温预报的时间平均不一致性指数差异较大。ECM WF时间不一致性指数最小,NCEP次之,CM A最大。另外NCEP的控制预报、ECM WF的控制预报和集合平均预报,这三者的时间平均不一致性指数随预报时效延长而增加,且集合平均预报一致性优于控制预报。而对于CMA预报的不一致性,无论是控制预报还是集合平均预报总体上都稳定地保持在较高的水平。此外,ECMWF的地面气温冬(夏)季预报的不一致性相对较强(弱),且单点跳跃随预报时效延长变化不明显,而控制预报和集合平均预报的异号两点跳跃以及三点跳跃出现的频率总体上随预报时效延长略有增加。 相似文献
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Studies of interactions between wind and saltating particles （i.e., the wind-saltation interaction） are usually conducted without consideration of the downwind air pressure gradient. However, in a wind tunnel with limited size, this gradient is required to maintain the movement of the saltation cloud. Attempts are made to investigate the effects of the downwind air pressure gradient on the wind-saltation interaction in a saltation boundary layer based on the experimental results from a wind tunnel with a relatively small cross-sectional area. The wind-saltation interaction is characterized by airborne stress, grain-borne stress, and the force exerted on the wind by the saltation cloud. Basic equations were developed for wind-saltation interactions without and with a downwind air pressure gradient. The results reveal that unacceptable values of negative grain-borne stress and negative force exerted on the wind by the saltation cloud are obtained if the downwind air pressure gradient is ignored. When this air pressure gradient is defined using the measured wind velocity profiles in the presence of saltation and the downwind air pressure gradient is taken into account, reasonable values for grain-borne stress and the force exerted on the wind by the saltation cloud are obtained. These results suggest that attention must be paid to the effects of downwind air pressure gradients when studying the wind-saltation interaction in a wind tunnel. Consideration of the downwind air pressure gradient, inertial forces, and other unidentified variables will provide a more thorough understanding of the interactions within a saltation boundary layer. 相似文献
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在采集得到地震数据中,随机噪声常常与有效信号混合在一起,并且毫无规律,使用常规去噪方法不能够达到理想的效果,影响后续的地震数据处理工作.为有效压制地震数据中的随机噪声,本文根据深度学习的相关理论,提出了一种基于深度卷积自编码网络的数据驱动的去噪方法,可以解决随机噪声难以去除的问题.在卷积自编码器的基础之上,网络使用了较多的层数并加入跳跃连接构造,从而增加了网络的深度,能够提取并结合数据中深层与浅层特征,增强对随机噪声的处理能力,更好地恢复有效信号的细节.经过实验证明该方法对于不同水平的随机噪声的压制均有优异的表现,在去噪的效果上远超中值滤波、小波变换等传统去噪方法,同时也比经典的DnCNN网络更加优秀,能够完整地保留有效信号,极大提升地震数据的质量. 相似文献
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为探究不同远期运费市场之间的风险联动性,文章采用SVCJ-TVP-VAR模型,选取2014—2020年3种船型远期运费(FFA)日度数据,从静态和动态的角度分析国际干散货FFA市场间收益跳跃及波动跳跃的联动关系。研究结果表明：(1)交易活跃的好望角船型FFA市场的跳跃现象最明显,超灵便船型FFA市场跳跃现象最弱;(2)从共跳的角度来看,3个市场整体发生跳跃的情况弱,但两市场之间共跳情况较强,其中好望角船型和巴拿马船型共跳次数最多;(3)远期运费市场两两之间存在时变且复杂的双向联动关系,且这种联动效应在短期最强,长期最弱;(4)无论是收益跳跃和还是波动跳跃,3种市场对跳跃信息均具有不同的反应程度。好望角船型FFA市场对跳跃信息的反应程度最剧烈,且其他市场对好望角船型市场的跳跃信息的响应程度最高;(5)在造成市场整体低迷的极端事件发生时,FFA市场往往表现出正向的跳跃联动效应,这对市场监管者和参与者提供了参考意义。 相似文献
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