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针对燃气轮机状态评估过程中参与组合的单一评估方法选择不明确和组合评价结果不一致的问题,提出一种事前事后检验和重复组合的综合评价方法。选取表征性能退化和振动状态的12个评价指标来评估整体的健康状态,在8种单一评价方法的基础上,用传统Borda法、综合Borda法、Copeland法、模糊Borda法和Dodgson法等5种组合评价方法对燃气轮机健康状态进行了多指标综合评价。在组合步骤中,参与组合的单一评估方法要通过Kendall协同系数检验和Spearman等级相关系数检验,组合后如果评价结果排序不一致,通过Spearman等级相关系数检验剔除与原单一评价不相关的组合方法后,其余组合结果再重复组合,以得到排序一致的综合评价结果。实例分析表明,组合法综合评价结果符合实际经验。 相似文献
153.
通过分析目前大多数内地高职院校商务英语实训的模式及其存在的问题,以外贸函电为例,阐明基于网络的商务英语实训模式的可行性和操作方法。表明应用语言类专业学生的综合能力需要通过实训来提高,但由于实训过程的特殊性,我国内地高职院校很难找到真正"工学结合"的实训机会。为了促进企业和学校的合作,应把这类实训活动作为长期活动,为合作的企业提供长期的服务,从而真正实现"工学结合"的目的。 相似文献
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《中国航空学报》2020,33(3):1006-1015
When non-cooperative body attachment occurs in space, the inertia of the new combination and the change of the system’s momentum are unknown. This uncertainty may lead to the instability of the spacecraft’s attitude control. In order to solve this problem, we propose an adaptive control scheme based on the inertia estimation of the new, combined system of non-cooperative body and satellite. This method can allow the new combination of different situations to reach a stable state with a high level of precision and speed. In this paper, the stability of the adaptive control scheme is proven by constructing a Lyapunov function. A simulation environment in which a non-cooperative body attaches to a satellite attaches to is constructed. The simulation shows that the attitude error converges to a small field when using the control scheme, regardless of unfavorable cases, including unknown inertia parameters, added momentum. In addition, the simulation results show the strong robustness of the control scheme for the new combination. 相似文献
156.
Tamara Bandikova Jakob Flury 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The new release of the sensor and instrument data (Level-1B release 02) of the Gravity Recovery and Climate Experiment (GRACE) had a substantial impact on the improvement of the overall accuracy of the gravity field models. This has implied that improvements on the sensor data level can still significantly contribute to arriving closer to the GRACE baseline accuracy. The recent analysis of the GRACE star camera data (SCA1B RL02) revealed their unexpectedly higher noise. As the star camera (SCA) data are essential for the processing of the K-band ranging data and the accelerometer data, thorough investigation of the data set was needed. We fully reexamined the SCA data processing from Level-1A to Level-1B with focus on the combination method of the data delivered by the two SCA heads. In the first step, we produced and compared our own combined attitude solution by applying two different combination methods on the SCA Level-1A data. The first method introduces the information about the anisotropic accuracy of the star camera measurement in terms of a weighing matrix. This method was applied in the official processing as well. The alternative method merges only the well determined SCA boresight directions. This method was implemented on the GRACE SCA data for the first time. Both methods were expected to provide optimal solution characteristic by the full accuracy about all three axes, which was confirmed. In the second step, we analyzed the differences between the official SCA1B RL02 data generated by the Jet Propulsion Laboratory (JPL) and our solution. SCA1B RL02 contains systematically higher noise of about a factor 3–4. The data analysis revealed that the reason is the incorrect implementation of algorithms in the JPL processing routines. After correct implementation of the combination method, significant improvement within the whole spectrum was achieved. Based on these results, the official reprocessing of the SCA data is suggested, as the SCA attitude data are one of the key observations needed for the gravity field recovery. 相似文献
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对于有限可重组合问题 ,通常用母函数方法[1] 作解答 ,但当数据比较大时 ,母函数方法就不太方便。更重要的是 ,母函数方法很难在计算机中实现。本文对几种有限可重组合问题给出了公式型解法 相似文献
160.
本模型意在寻求净收益R尽可能大而风险ε尽可能小的一种投资组合,先介绍了在期望风险为一定值时单纯形法求解净收益最大的投资组合的全过程。 相似文献