Orbital evolution of a planet with tidal dissipation in a restricted three-body system     

Wen-Lei Wang  Xue-Qing Xu  Xin-Hao Liao 《天文和天体物理学研究(英文版)》2019,(9)

The angle between planetary spin and the normal direction of an orbital plane is supposed to reveal a range of information about the associated planetary formation and evolution. Since the orbit's eccentricity and inclination oscillate periodically in a hierarchical triple body and tidal friction makes the spin parallel to the normal orientation of the orbital plane with a short timescale in an isolated binary system, we focus on the comprehensive effect of third body perturbation and tidal mechanism on the angle. Firstly, we extend the Hut tidal model(1981) to the general spatial case, adopting the equilibrium tide and weak friction hypothesis with constant delay time, which is suitable for arbitrary eccentricity and any angle ? between the planetary spin and normal orientation of the orbital plane. Furthermore, under the constraint of angular momentum conservation, the equations of orbital and ratational motion are given. Secondly, considering the coupled effects of tidal dissipation and third body perturbation, and adopting the quadrupole approximation as the third body perturbation effect, a comprehensive model is established by this work. Finally, we find that the ultimate evolution depends on the timescales of the third body and tidal friction. When the timescale of the third body is much shorter than that of tidal friction, the angle ? will oscillate for a long time,even over the whole evolution; when the timescale of the third body is observably larger than that of the tidal friction, the system may enter stable states, with the angle ? decaying to zero ultimately, and some cases may have a stable inclination beyond the critical value of Lidov-Kozai resonance. In addition, these dynamical evolutions depend on the initial values of the orbital elements and may aid in understanding the characteristics of the orbits of exoplanets.  相似文献   

动态应力触发研究进展     

陈昊  冀战波  王琼  苏金波 《中国地震》2020,36(3):442-459

本文从库仑破裂应力与动态应力触发原理、观测事实与研究现状以及存在的问题与展望等3个方面介绍了动态应力触发的研究进展。其中,在主震对余震活动、强震对后续远场地震活动、不同破裂类型的地震之间及强震对火山(泥火山)的动态应力触发作用、一次大地震中子事件之间的动态应力触发关系以及动态应力触发的时间延迟等方面进行了详细讨论。分析认为,动态应力触发理论在解释震后余震分布、远程触发以及对火山触发性喷发等方面得到了较好的结果;动态应力触发可能会受断层破裂方式和方向的影响;大地震中子事件之间的动态应力触发关系对震源研究有重要意义;动态应力触发现象普遍存在时间延迟。  相似文献   

A three-dimensional variational data assimilation system for a size-resolved aerosol model: Implementation and application for particulate matter and gaseous pollutant forecasts across China     

Wang  Daichun  You  Wei  Zang  Zengliang  Pan  Xiaobin  He  Hongrang  Liang  Yanfei 《中国科学:地球科学(英文版)》2020,63(9):1366-1380

A three-dimensional variational(3DVAR) data assimilation(DA) system is presented here based on a size-resolved sectional aerosol model, the Model for Simulating Aerosol Interactions and Chemistry(MOSAIC) within the Weather Research and Forecasting model coupled to Chemistry(WRF-Chem) model. The use of this approach means that both gaseous pollutants such as SO_2, NO_2, CO, and O_3 as well as particulate matter(PM_(2.5), PM_(10)) observational data can be assimilated simultaneously.Two one-month parallel simulation experiments were conducted, one with the assimilation of surface hourly concentration observations of the above six pollutants released by the China National Environmental Monitoring Centre(CNEMC) and one without assimilation in order to verify the impact of assimilation on initial chemical fields and subsequent forecasts. Results show that, in the first place, use of the DA system can provide a more accurate model initial field. The root-mean-square error of PM_(2.5), PM_(10), SO_2, NO_2, CO, and O_3 mass concentrations in analysis field fell by 29.27 μg m~(-3)(53.5%), 34.5 μg m~(-3)(50.9%),30.36 μg m~(-3)(64.2%), 8.91 μg m~(-3)(39.5%), 0.46 mg m~(-3)(47.4%), and 15.11 μg m~(-3)(51.0%), respectively, compared to a background field without assimilation. At the same time, mean fraction error was reduced by 42.6%, 53.1%, 45.2%, 43.1%,69.9%, and 48.8%, respectively, while the correlation coefficient increased by 0.51, 0.55, 0.48, 0.38, 0.47, 0.65, respectively.Secondly, the results of this analysis reveal variable benefits from assimilation on different pollutants. DA significantly improves PM_(2.5), PM_(10), and CO forecasts leading to positive effects that last more than 48 h. The positive effects of DA on SO_2 and O_3 forecasts last up to 8 h but that remains relatively poor for NO_2 forecasts. Thirdly, the influence of assimilation varies in different areas. It is possible that the positive effects of DA on PM_(2.5) and PM_(10) forecasts can last more than 48 h across most regions of China. Indeed, DA significantly improves SO_2 forecasts within 48 h over north China, and much longer CO assimilation benefits(48 h) are found in most regions apart from north and east China and across the Sichuan Basin. DA is able to improve O_3 forecasts within 48 h across China with the exception of southwest and northwest regions and the O_3 DA benefits in southern China are more evident, while from a spatial distribution perspective, NO_2 DA benefits remain relatively poor.  相似文献   

四川地区震后应急会商资料快速产出系统的设计与实现     

祁玉萍  汪小厉  林圣杰  肖本夫  何畅  廖晓峰 《震灾防御技术》2020,15(1):176-183

地震预报意见以大量资料为基础，依靠专家经验和多学科知识并通过会商讨论形成。显著地震发生后，快速、准确、有效地研判震情可为后期应急指挥和地震现场工作奠定基础。本文以Datist软件为平台，基于四川及邻区的基础资料，设计研发符合四川震情的震后会商资料快速产出系统，当四川及邻区发生中强地震时，通过该系统可在收到地震短信5分钟内以请求触发的方式快速产出应急会商资料，并以微信、PowerPoint和Word的形式将基础资料发送给分析预报人员，为后期趋势分析奠定基础。  相似文献   

不锈钢纤维网对热压铁基预合金胎体抗冲击韧性的影响          下载免费PDF全文

孙吉伟  吴海霞  沈立娜  杨甘生 《探矿工程》2020,47(2):73-77

针对孕镶金刚石钻头在孔底钻进时受到各种冲击力而导致胎体出现裂纹甚至断裂的问题，提出了应用不锈钢纤维网提高胎体抗冲击韧性的方法。通过控制纤维网的摆放位置、目数和层数3个变量，测试了不同组合变量下的胎体抗冲击韧性。通过试验得到：（1）不锈钢纤维网能有效提高胎体的抗冲击韧性，而且X轴位置效果更好；（2）当纤维网的目数相同时，胎体抗冲击韧性随纤维网层数的增加而减小；（3）在纤维网层数相同的情况下，随着纤维网目数的增加，胎体抗冲击韧性呈现先增大后减小的趋势。当添加30目单层纤维网时，胎体的抗冲击韧性达到最大值。通过观察冲击断口、分析胎体断裂机理，解释了出现这种规律的原因，并提出了进一步优化胎体抗冲击韧性的方法。  相似文献   

Application of Lithium Isotope Geochemistry to the Study of the Continental Geothermal System     

Xiaocan Yu  Chenglin Liu  Chunlian Wang 《地球科学进展》2020,35(3):246-258

The lithium-rich brine in salt lakes is the main raw material of the world’s lithium products, while the continental geothermal fluids with a high salinity often contain a high concentration of lithium. Continental geothermal system is the focus in the study of geothermal formation mechanism. However, less attention is paid to the system due to the complexity of lithology, and the application of lithium isotopes in this field has not been systematically recognized. The newest application and progress of lithium isotope geochemistry in continental geothermal research in recent years were discussed, the problems in this field were put forward, and future research methods and directions were expected. The study of continental geothermal fluids should attach great importance to the application of Li-B-Sr-U multi-isotopic method, and should also be combined with water-rock reaction experiments under different temperature conditions. Moreover, in the future, the research on continental geothermal system should pay more attention to the various sediment/rock lithium isotopic compositions and their spatio-temporal distribution characteristics in the regional or geothermal field’s scales, mineralogy of reservoir rock, and behaviors of lithium isotopes related to the formation of secondary minerals in the process of water-rock interaction, in order to reveal the complex process of fluid evolution in the geothermal system and provide scientific reference for the exploration, exploitation and utilization of lithium resources in the system.  相似文献   

Decision-making for ecological landslide prevention in tropical rainforests     

Wang  Lunyan  Li  Wenmin  Li  Huimin 《Natural Hazards》2020,103(1):985-1008

Natural Hazards - Landslide disasters in tropical rainforests are becoming increasingly severe. It is a tough task to prevent and control landslide effectively in the tropical rainforests....  相似文献   

Risk assessment through multivariate analysis on the magnitude and occurrence date of daily storm events in the Shenzhen bay area     

Jing-Cheng Han  Yang Zhou  Yuefei Huang  Xiaofeng Wu  Zhe Liu  Yongqiang Wang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(5):669-689

Multivariate storm frequency modeling would help to gain improved understanding of complex storm process, and provide useful information for regulating flooding risk. In this paper, the dependency...  相似文献   

河北省怀安县朱家洼矿区地球化学特征与找矿方向     

王占彬 《地质与勘探》2020,56(1):102-112

河北怀安朱家洼矿区位于华北板块北缘中段太古宙、元古宙、中生代金银铅锌铁硫铁矿成矿带,为火山热液型金多金属矿。为查明该区成矿规律,明确找矿方向,在区内开展了水系沉积物测量、土壤地球化学测量等工作。通过对元素分布、元素相关性、元素异常等特征研究表明,Au、Mo为本区主成矿元素;各元素异常平面分布具有分带性,高温元素W、Sn、Bi异常位于骆驼山火山机构中心,中低温元素Pb、Zn、As、Ag等异常分布于火山机构边部及周边围岩中,成矿元素Au、Mo异常主要位于火山机构西侧围岩中。异常查证发现金钼矿化体2条,金钼矿化受火山机构和北西向构造带控制。依据成矿地质条件、地球化学异常及查证成果认为,朱家洼矿区Au、Mo成矿潜力大,火山机构西侧围岩区是该区重点找矿地段。  相似文献   

Increasingly important role of numerical modeling in oceanic observation design strategy: A review     

Zhang  Kun  Mu  Mu  Wang  Qiang 《中国科学:地球科学(英文版)》2020,63(11):1678-1690

Science China Earth Sciences - Oceanic observation design is of considerable significance and has made remarkable progress during the past several decades. This study addresses the critical role of...  相似文献