科创中国

Recently-developed capabilities for tracking the movements of individual birds over the course of a year or longer has provided increasing evidence for consistent individual differences in migration schedules and destinations. This raises questions about the relative importance of individual consistency versus flexibility in the evolution of migration strategies, and has implications for the ability of populations to respond to climatic change. Using geolocators, we tracked the migrations of Scopoli's shearwaters Calonectris diomedea breeding in Linosa (Italy) across three years, and analysed timing and spatial aspects of their movements. Birds showed remarkable variation in their main wintering destination along the western coast of Africa. We found significant individual consistency in the total distance traveled, time spent in transit, and time that individuals spent in the win- tering areas. We found extensive sex differences in scheduling, duration, distances and destinations of migratory journeys. We also found sex differences in the degree of individual consistency in aspects of migration behaviour. Despite strong evidence for individual consistency, which indicates that migration journeys from the same bird tended to be more similar than those of dif- ferent birds, there remained substantial intra-individual variation between years. Indeed, we also found clear annual differences in departure dates, return dates, wintering period, the total distance traveled and re~rn routes from wintering grounds back to the colony. These findings show that this population flexibly shifts migration schedules as well as routes between years in response to direct or indirect effects of heterogeneity in the environment, while maintaining consistent individual migration strategies [Current Zoology 60 (5): 631-641, 2014].

在机器人轨迹规划、数控机床刀具路径规划等应用中,基于分离距离的碰撞检测算法能在物体碰撞发生前预警并使系统做出相应响应,具有广泛应用和重要研究意义.分析基于分离距离的碰撞检测算法处理流程,就精确检测阶段分离距离计算所应用的基本原理对基于分离距离的碰撞检测算法从包围体层次树、代数几何、几何特征、单纯形法、数学规划、距离场等区分角度进行分析与讨论.归纳与总结碰撞检测对象正朝着多表现形式、非凸、有形变、多物体发展,碰撞检测算法正朝着动态检测、连续检测、并行化发展.最后,指出碰撞检测算法亟待解决的一些问题.

虚拟内窥镜自动漫游的中心路径提取采用边界距离变换算法实现.通过判断与组织相关的体素点、计算体素点的ID值和灰度值、标记处理点并将其作为新的边界点的方法来缩短边界距离场的建立时间;利用下标与体素点的边界距离一致的结构体数组作为快速查找表,将体素点按照其边界距离链接到数组的相应位置,每次选取位于数组下标最大位置的点进行处理,利用数组查询时间复杂度低的方法提高建立源距离场的时间效率.实验结果表明该实现方法时间效率高,提取的中心路径漫游效果好,实时性好.

消防车自动行驶中的排档控制装置,其总体结构是采用内置式组合气缸,安装在气动滑台上且组合了推板和导杆,组成了一套消防车排档气动集成控制装置,可在消防车的换档箱附近狭小空间安装,完成切档、挂档、脱开的动作.应用气动控制使装置体积小、调试方便、定位准确、免维护,其中采用的单电控电磁阀能做到在汽车意外断电时气动滑台和组合气缸能安全复位.

建立了某型步兵战车行驶动力学仿真模型并基于实车行驶试验建立支持向量机响应面对仿真模型进行了修正.根据仿真路面与约束关系对步兵战车行驶动力学模型进行了仿真计算;提取典型节点行驶过程中的垂向加速度功率谱密度相似度作为目标函数,引入支持向量机响应面作为修正算法,修正了步兵战车悬挂与座圈刚度-阻尼系数.修正结果表明基于支持向量机响应面的模型修正方法大幅提高了车体动力学模型精度,更准确的反映了步兵战车行驶过程中的机构动态特性.

跑偏是履带推土机常见的故障现象.分析了其跑偏方式及原因,设计了一种履带式全液压推土机行驶实时纠偏控制系统.该系统采用三维数字罗盘姿态传感器,信息送至控制器处理后得到推土机的偏转方向及偏转量数值,通过数字液压缸控制变量马达的排量,进而改变变量马达转速实现纠偏,克服了现有推土机行驶纠偏装置的缺点.

在多义词义项辨识或词义消歧中,义项划分的标准具有重要的制约作用.义项距离是进行义项划分的重要参考.多义动词义项距离与动词义项的三种组合特征-语义组合特征、语法组合特征及固定搭配特征密切相关,并由这三种特征的距离共同决定.在对100个现代汉语双义项动词的义项距离进行计算的基础上,可以得到动词义项的分合标准.

0引言两人一起抬某个物体在我们生活中是非常常见的现象,而且在两人抬一个物体时通常会有人建议个高的在后面抬,个矮的在前面抬;或者是建议劲大的抬物体的大头,或者建议劲大的抬得时候距离重心近一些,劲小的距离重心远一些.上面的生活现象都是我们所知道事实,我们自己也时不时会遇到这样的情况,但是其中的道理是什么,却需要仔细思考,特别是从力学的角度加以讨论.为了能让我们更清楚的知道这种现象所蕴含的力学原理,我们将从以下几步来展开讨论.1两人抬物体的力学模型的建立一般情况下,我们抬物体时对物体的作用点距离物体的重心并不相等,两人身高也并不是绝对相等,工作的地面也不完全是水平面等客观现实的存在,因此我们在建立这个力学模型时需要把这些因素考虑进去,因此我们对力学模型的

高精度、高速度、大前瞻的路径采集系统能为智能车提高更精准、更及时和更丰富的赛道信息,是智能车获取更大速度的关键.针对激光传感器的路径采集模块,设计了一种路径识别算法,经过实验,该算法可以使智能车准确、及时地获取赛道信息,提升了智能车的速度和稳定性.

Human activity has been shown to influence how animals assess the risk of predation, but we know little about the spatial scale of such impacts. We quantified how vigilance and flight behavior in mule deer Odocoileus hemionus varied with distance from an area of concentrated human activity--a subalpine field station. An observer walked trails at various distances away from the station looking for deer. Upon encounter, the observer walked toward the focal animal and noted the distance at which it alerted and directed its attention to the approaching human (Alert Distance; AD), and the distance at which it fled (Flight Initiation Distance;. FID). AD and FID both increased nonlinearly with distance from the center of the field station, reaching pla- teaus around 250 m and 750 m, respectively. Deer also tended to flee by stotting or running, rather than by walking, when far from the station but they walked away when near the station. These results indicate that deer perceive lower risk near a focused area of human activity, and that vigilance and flight behaviors respond on somewhat different spatial scales. The concept of a spatial "human footprint" on behavior may be useful for understanding how human activities affect wildlife