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1.
Most earth observation satellites(EOSs)are low-orbit satellites equipped with optical sensors that cannot see through clouds.Hence,cloud coverage,high dynamics,and cloud uncertainties are important issues in the scheduling of EOSs.The proactive-reactive scheduling framework has been proven to be effective and efficient for the uncertain scheduling problem and has been extensively employed.Numerous studies have been conducted on methods for the proactive scheduling of EOSs,including expectation,chance-constrained,and robust optimization models and the relevant solution algorithms.This study focuses on the reactive scheduling of EOSs under cloud uncertainties.First,using an example,we describe the reactive scheduling problem in detail,clarifying its significance and key issues.Considering the two key objectives of observation profits and scheduling stability,we construct a multi-objective optimization mathematical model.Then,we obtain the possible disruptions of EOS scheduling during execution under cloud uncertainties,adopting an event-driven policy for the reactive scheduling.For the different disruptions,different reactive scheduling algorithms are designed.Finally,numerous simulation experiments are conducted to verify the feasibility and effectiveness of the proposed reactive scheduling algorithms.The experimental results show that the reactive scheduling algorithms can both improve observation profits and reduce system perturbations. 相似文献
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ZHANG XiaoLii HE Xini LIU DingZheni YAO XiuLini ZHANG YiZhuo ZHANG EnQuan ZHANG JinGuo JIANG GuoHua ZHAO ChangQi 《科学通报(英文版)》2013,58(18):2220-2229
The effects of individual removal by zoo managers on behavior and fecal glucocorticoid changes in snub-nosed monkeys(Rhinopithecus roxellana) were investigated at Beijing Zoo.The results showed that the effect of the removal of three subordinate individuals(DD,male,4 years;XZZ,male,3 years and LL,female,3 years) from a group varied across the remaining group members that may be related to individual’s social status,gender and age.The dominant male was impacted less than subordinate individuals in both the frequency and time duration for the four main behavioral categories.The frequency of stereotypic behavior significantly decreased in the dominant female after the removal of three animals(Z= 2.862,P=0.003).Fluctuations were found in both the behavioral frequency and time duration in other remaining individuals.These findings suggest that small,socially stable groups were somewhat resilient to changes in member composition.Moreover,the cortisol level did not change significantly in the remaining members.An alternative method of hormone assay using fecal samples for vulnerable animals was presented,and that may be useful for monitoring wild golden monkeys and other endangered species of animal. 相似文献
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XU XiWei WEN XueZe HAN ZhuJun CHEN GuiHua LI ChuanYou ZHENG WenJun ZHNAG ShiMin REN ZhiQun XU Chong TAN XiBin WEI ZhanYu WANG MingMing REN JunJie HE ZhongTai LIANG MingJian 《科学通报(英文版)》2013,(Z2):3437-3443
In the epicenter of the Lushan MS7.0 earthquake there are several imbricate active reverse faults lying from northwest to southeast,namely the Gengda-Longdong,Yanjing-Wulong,Shuangshi-Dachuan and Dayi faults.Emergency field investigations have indicated that no apparent earthquake surface rupture zones were located along these active faults or their adjacent areas.Only brittle compressive ruptures in the cement-covered pavements can be seen in Shuangshi,Taiping,Longxing and Longmen Townships,and these ruptures show that a local crustal shortening occurred in the region during the earthquake.Combining spatial distribution of the relocated aftershocks and focal mechanism solutions,it is inferred that the Lushan earthquake is classified as a typical blind reverse-fault earthquake,and it is advised that the relevant departments should pay great attention to other historically un-ruptured segments along the Longmenshan thrust belt and throughout its adjacent areas. 相似文献
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设计了一个针对多发性硬化症患者的三维步态分析实验,利用三维光学捕捉系统对实验被试身体不同部位标记点的三维坐标进行追踪和记录,成功发现了多个步态参数发生的变化,这些变化不仅能反映实验被试细微的步态功能上的变化,而且还与接受治疗的时间密切相关。此套基于步态数据的量化评估体系能够弥补目前广泛应用的评估方法主观和不够准确的缺点,为临床医生改进治疗方案以及制定更加有效的治疗方法提供帮助。 相似文献
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Rest A Prieto JL Walborn NR Smith N Bianco FB Chornock R Welch DL Howell DA Huber ME Foley RJ Fong W Sinnott B Bond HE Smith RC Toledo I Minniti D Mandel K 《Nature》2012,482(7385):375-378
η?Carinae is one of the most massive binary stars in the Milky Way. It became the second-brightest star in our sky during its mid-nineteenth-century 'Great Eruption', but then faded from view (with only naked-eye estimates of brightness). Its eruption is unique in that it exceeded the Eddington luminosity limit for ten years. Because it is only 2.3 kiloparsecs away, spatially resolved studies of the nebula have constrained the ejected mass and velocity, indicating that during its nineteenth-century eruption, η?Car ejected more than ten solar masses in an event that released ten per cent of the energy of a typical core-collapse supernova, without destroying the star. Here we report observations of light echoes of η?Carinae from the 1838-1858 Great Eruption. Spectra of these light echoes show only absorption lines, which are blueshifted by -210?km?s(-1), in good agreement with predicted expansion speeds. The light-echo spectra correlate best with those of G2-to-G5 supergiants, which have effective temperatures of around 5,000?kelvin. In contrast to the class of extragalactic outbursts assumed to be analogues of the Great Eruption of η?Carinae, the effective temperature of its outburst is significantly lower than that allowed by standard opaque wind models. This indicates that other physical mechanisms such as an energetic blast wave may have triggered and influenced the eruption. 相似文献
7.
传统的科学观认为实验的可重复性是自明和不可或缺的,可重复的原则是科学事实成立的重要判据,是科学确定性、普遍性的奠基石.SSK和新实验主义都对这一原则进行了深入的分析,指出了传统观点在此问题上的缺陷.尽管如此,SSK和新实验主义由于关注点、研究方法和认识论等方面的不同,各自的研究思路和结论也有差异.本文主要探讨并比较了两者对实验可重复性的相关研究,最后对如何看待实验可重复性提出一点见解. 相似文献
8.
This paper proposes a novel distributed optimization algorithm with fractional order dynamics to solve linear algebraic equations. Firstly, the authors proposed “Consensus + Projection” flow with fractional order dynamics, which has more design freedom and the potential to obtain a better convergent performance than that of conventional first order algorithms. Moreover, the authors prove that the proposed algorithm is convergent under certain iteration order and step-size. Furthermore,the author... 相似文献
9.
HE DengFa ZHOU XinYuan ZHANG ChaoJun YANG XiaoFa 《科学通报(英文版)》2007,52(A01):164-177
The Ordovician system is an important target for exploration in the Tarim Basin. Restoration of the Ordovician tectono-depositional environment is a key basis for the study of the structural development history in Tarim block and the prediction of the favorable Ordovician reservoir belts (zones). Based on the surrounding tectonic settings, the litho-facies and sedimentary fill, the palaeo-geography, palaeoclimate and palaeo-ecology, and the structural deformation and magmatic eruptions, in this paper we combine the sedimentary fill in the basin with the development of the surrounding orogenic belts and re-build the proto-type basins of the different Ordovician periods. During the Ordovician period, the Tarim region was characterized by the composite of the interior cratonic depression with the peripheral cratonic depression. The interior cratonic depression in the central and western parts is mainly the deposiUonal area of the platform facies while the peripheral cratonic depression in the eastern part is mainly the zone of deepwater basin facies, with the slope acting as the transition belt between them. During the Late Ordovician period, the closure of the Northern Kunlun Ocean and destruction of the trench-arc-basin system in the Altyn Tagh region put the southern part of the Tarim block under com- pression and uplifting and turned the central and western parts of the carbonate platform into the mixed deposiUonal continental shelf. The eastern region of the basin had the over-compensated flysch sedimentation with huge thickness, marking the drastic turn of the basin nature. The basin tectonic framework turned to the south-north differentiation of the Silurian period from the east-west differentiation of the Ordovician period. 相似文献
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