Reusing Test Cases Based on the Function Point

Reusing test cases from existing test case library is quite common in the software testing field. Testing practice tells us that there is a strong relationship between the granularity of a function unit under testing and that of the test case. A function unit with small granularity usually results in the test cases with the same small granularity. Therefore a test case defined as the function point,i. e.,the smallest size function unit,was provided for the first time.Though test cases with smaller granularity usually have better reusability,the cost of accurately reusing and integrating such test cases is also higher. In order to balance the test case reusability and the cost of test case reuse,a novel test case reuse model based on the function point was proposed in this paper. In this model,a reusable test case for specification-based testing was defined and some reuse strategies and three formal reuse methods were given. Finally,the complete automatic software process was realized by a reusing generation tool. The new method has improved reuse accuracy,while greatly enhances the software productivity.     

Deformation heterogeneity of Ti under cryogenic channel-die compression

Commercial purity Ti was subjected to channel die compression in liquid nitrogen for the purpose of studying its deformation characteristics from the viewpoint of the grain refinement induced by severe plastic deformation.Deformed specimens showed microstructural heterogeneity in that the initial blocky grains of about 50 urn in size turned into a mixture of the easily deforming soft grains and the hard grains revealing local concentration of dislocations and deformation twins.Using electron back scatter...     

Deformation heterogeneity of Ti under cryogenic channel-die compression

Commercial purity Ti was subjected to channel die compression in liquid nitrogen for the purpose of studying its deformation characteristics from the viewpoint of the grain refinement induced by seve re plastic deformati on. Deformed specimens showed microstructural heterogeneity in that the initial blocky grains of about 50 μm in size turned into a mixture of the easily deforming soft grains and the hard grains revealing local concentration of dislocati ons and deformation twins. Using electron back scattered diffraction analysis the in-grain misorientation-axis distribution was studied, from which it was found that the deformation heterogeneity resulted from the anisotropy of individual grains with respect to the compression die: while the soft grains were those oriented favorably for the prism < a> slip, the hard ones were oriented for non-prism slips and deformation twinning. The difference in the response of individual grains, therefore, led to a remarkable effect of the crystal texture of specimens on the maximum strain that can be imposed on specimens without cracking. Based on the present results, a way to achieve expedient grain refinement through the cryogenic plane-strain compression was suggested.     

Improved threshold retracker for satellite altimeter waveform retracking over coastal sea

Data quality is a key factor for the application of satellite altimetry to geodesy and oceanography. Accuracy of altimetry is limited in the coastal area because the altimeter waveforms are seriously contaminated by topography and environmental pollution. So waveform retracking is needed to compute the range correction of geophysical data records (GDRs) for better accuracy. In this paper, a new waveform retracker named the improved threshold retracker (ITR) is put forward. The retracker first builds sub-waveforms based on leading edges detected in a waveform, then determines the middle point of each leading edge to compute the retracking range correction, finally calculates the referenced sea surface heights according to the geoid undulation from a local geopotential model and tide heights from an ocean tide model, and compares it with all retracking ranges to determine the best one. As a test, altimeter waveforms of Geosat/GM are retracked around the Taiwan coastal area. The result shows that accuracy of ITR method is two times better than that of the β-5-parameter function-fitting method and threshold method, and three times better than that of GDRs. ITR can efficiently improve the altimetry accuracy of the coastal sea area.     

不同侧压系数下各向异性巷道围岩破坏模式研究

针对各向异性初始应力状态(不同的侧压力系数下)的岩体巷道开挖问题,利用复合材料的Hoffman强度准则考察各向异性对巷道周围应力、位移和塑性破坏区的影响.结果表明:巷道围岩的最大主应力与侧压系数无关,当θ=30°~60°时为最大,θ=0°,90°时为最小.随θ的增加,巷道围岩的水平位移增加,垂直位移减小.在各向异性岩体中强度较大的方向与最大应力方向一致时,破坏发生在此方向,塑性破坏区的范围为最大.     

采用邻居节点的改进ZigBee路由选择算法

在无线传感网络中,路由选择是高效使用网络、延长全网络寿命的关键之一.为了提高网络效率和节省网络整体能耗,提出了一种路由选择优化算法,该算法利用没连接到的邻居节点进行数据路由选择,以减少从源节点到目的节点的跳数,进而达到提高网络效率和节省能耗的目的.通过仿真实验对比分析了改进前后的实际效果,实验结果表明改进后的路由选择优化算法减少了ZigBee节点间路由的跳数和延迟,提高了路由效率,节省网络整体能耗.     

点云质量评价挑战与关键技术研究

近年3D数据采集和处理技术快速发展,点云作为一种典型的3D媒体数据类型引起越来越多的关注,其在无人驾驶、混合现实、测绘和医学影像等多个领域的发展上起到了巨大作用.与传统的图像、视频类似,点云在计算处理过程中会不可避免的引入各种失真,因此,合理准确的点云质量评价模型尤为重要.本文首先分析点云质量评价存在的挑战与困难;然后从点云主观实验方法、数据库构建和客观模型设计三个方面阐述研究现状;针对其关键技术进行分析和探索,并介绍本团队在点云主观质量评价标准化、数据库构建和客观模型设计上取得的阶段成果和未来展望.