Smooth support vector machine （SSVM） changs the normal support vector machine （SVM） into the unconstrained op- timization by using the smooth sigmoid function. The method can be solved under the Broyden-Fletcher-G...Smooth support vector machine （SSVM） changs the normal support vector machine （SVM） into the unconstrained op- timization by using the smooth sigmoid function. The method can be solved under the Broyden-Fletcher-Goldfarb-Shanno （BFGS） algorithm and the Newdon-Armijio （NA） algorithm easily, however the accuracy of sigmoid function is not as good as that of polyno- mial smooth function. Furthermore, the method cannot reduce the influence of outliers or noise in dataset. A fuzzy smooth support vector machine （FSSVM） with fuzzy membership and polynomial smooth functions is introduced into the SVM. The fuzzy member- ship considers the contribution rate of each sample to the optimal separating hyperplane and makes the optimization problem more accurate at the inflection point. Those changes play a positive role on trials. The results of the experiments show that those FSSVMs can obtain a better accuracy and consume the shorter time than SSVM and lagrange support vector machine （LSVM）.展开更多
空间环境指数是描述空间碎片对空间环境长期影响的量化评估指数。用该指数可以对比分析某空间物体的在轨运行是否对其他物体乃至整体环境产生较大威胁。对现有典型空间碎片环境指数及其建模方法进行分析和比较,并针对过去模型中平均碰...空间环境指数是描述空间碎片对空间环境长期影响的量化评估指数。用该指数可以对比分析某空间物体的在轨运行是否对其他物体乃至整体环境产生较大威胁。对现有典型空间碎片环境指数及其建模方法进行分析和比较,并针对过去模型中平均碰撞风险计算方法的不足,提出一种空间环境指数模型,即基于轨道间最小距离(minimum orbital intersection distance,MOID)的空间环境指数(MOID-based space index,MBSI)。该指数综合空间碎片的质量、有效截面积等因素,基于MOID考虑碰撞风险,计算近地轨道(low Earth orbit,LEO)区域中不同空间物体的MBSI指数,并与已有的R_(N)指数、CSI(criticality of spacecraft index,CSI)指数的结果进行比对和分析。MBSI与R_(N)指数、CSI指数符合度超过60%,而MBSI更能体现空间物体寿命期内的危险程度。展开更多
基金supported by the National Natural Science Foundation of China (60974082)
文摘Smooth support vector machine （SSVM） changs the normal support vector machine （SVM） into the unconstrained op- timization by using the smooth sigmoid function. The method can be solved under the Broyden-Fletcher-Goldfarb-Shanno （BFGS） algorithm and the Newdon-Armijio （NA） algorithm easily, however the accuracy of sigmoid function is not as good as that of polyno- mial smooth function. Furthermore, the method cannot reduce the influence of outliers or noise in dataset. A fuzzy smooth support vector machine （FSSVM） with fuzzy membership and polynomial smooth functions is introduced into the SVM. The fuzzy member- ship considers the contribution rate of each sample to the optimal separating hyperplane and makes the optimization problem more accurate at the inflection point. Those changes play a positive role on trials. The results of the experiments show that those FSSVMs can obtain a better accuracy and consume the shorter time than SSVM and lagrange support vector machine （LSVM）.
文摘空间环境指数是描述空间碎片对空间环境长期影响的量化评估指数。用该指数可以对比分析某空间物体的在轨运行是否对其他物体乃至整体环境产生较大威胁。对现有典型空间碎片环境指数及其建模方法进行分析和比较,并针对过去模型中平均碰撞风险计算方法的不足,提出一种空间环境指数模型,即基于轨道间最小距离(minimum orbital intersection distance,MOID)的空间环境指数(MOID-based space index,MBSI)。该指数综合空间碎片的质量、有效截面积等因素,基于MOID考虑碰撞风险,计算近地轨道(low Earth orbit,LEO)区域中不同空间物体的MBSI指数,并与已有的R_(N)指数、CSI(criticality of spacecraft index,CSI)指数的结果进行比对和分析。MBSI与R_(N)指数、CSI指数符合度超过60%,而MBSI更能体现空间物体寿命期内的危险程度。
