热海王星系统HD 106315的近$2:1$ 平运动共振捕获与轨道演化          下载免费PDF全文

黄秀敏  季江徽  董瑶 《天文学报》2020,61(5):54

通过结合理论分析和数值模拟方法,可以对热海王星系统HD 106315轨道迁移中的近2:1平运动共振捕获机制以及潮汐作用下的演化过程进行研究.在轨道迁移阶段,初始轨道半长径、初始偏心率以及行星c的偏心率衰减系数K会对系统轨道构型产生影响.数值模拟结果显示当初始轨道半长径分别为ab～0.4 au、ac～0.8 au,偏心率eb和ec均小于0.03时, HD 106315b和HD 106315c在中央恒星的引力作用以及原行星盘粘滞作用下向内迁移, 65000 yr左右两颗行星均可迁移至当前观测位置附近并形成近2:1平运动共振捕获.此外,中央恒星的潮汐效应也可能会对行星系统共振构型产生影响,理论分析表明当行星潮汐耗散系数Q=100时,潮汐效应造成的轨道半长径衰减使系统轨道周期比发生的变化可能是系统脱离共振构型的原因.数值模拟结果显示, HD 106315系统内两颗行星Q103时,来自中央恒星的潮汐效应并不会使行星系统产生明显的偏心率和轨道半长径衰减,不足以使HD 106315行星系统在剩余寿命内脱离2:1平运动共振轨道构型.  相似文献   

反应速率表达式与质量作用定律数学表达式的讨论     

孟燕  李雅丽 《地球科学与环境学报》1999,(Z1)

反应速率表达式与质量作用定律数学表达式都表示反应速率与反应物之间的定量关系。反应速率表达式适用于任何反应,质量作用定律仅适用于基元反应：ａＡ＋ ｂＢ ＝ ｄＤ＋ ｈＨ 只要温度Ｔ 确定,速率常数ｋ 就是一个确定的数值,ｋ 值是不会因表示反应速率的物质不同而改变其数值。对于同一化学反应,不管选用哪一反应物质浓度变化来表示,其反应速率γ都应该是同一数值。那么,如何正确选用不同物质的浓度变化来表示同一反应的反应速率呢？我们认为对于上述的一般反应：γ＝ － １ａｄｃＡｄｔ ＝ － １ｂｄＣＢｄｔ ＝ － １ｄｄＣＤｄｔ ＝ １ｈＣＨｄｔ ＝ ｋＣαＡ·ＣβΒ（α、β由实验测定）  相似文献   

考虑流-固耦合梁式矩形渡槽横向地震响应研究   总被引：1，自引：0，他引：1       下载免费PDF全文

季日臣  夏修身  陈尧隆  王丽 《地震学报》2007,29(3):328-334

根据豪斯纳尔（Housner）理论, 建立了考虑槽内水体与渡槽槽身流-固耦合的横向地震响应计算模型,分析了槽身断面深宽比变化对渡槽结构抗震的影响,并对某大型渡槽进行了多工况地震时程响应计算. 结果表明,在地震波作用下,渡槽槽内大质量水体对渡槽的横向地震响应有较大的影响, 但水体的晃荡作用有明显的TLD效应. 若将水体视为刚体, 质量全部附加到槽体上,将严重地夸大水的地震惯性力作用,且在渡槽槽身断面选择时应考虑深宽比对墩身地震响应的影响, 以减小地震力.   相似文献   

江西金家坞金矿地质特征及找矿前景     

詹天卫  鄢新华  王保林  刘家春 《地质与勘探》2007,43(2):23-27

金家坞金矿是近年江西省地矿局物化探大队发现的新矿产地,已基本查明是一个受近东西向构造挤压蚀变带控制的变质热液型大型金矿床.金矿化产于挤压蚀变变形带中,矿体形态简单、规模大,其成矿作用大致经历了火山沉积成岩-区域变质变形-动力变质热液改造等3个阶段.文章在系统阐述该矿地质特征和成矿地质条件的基础上,对其找矿远景进行了初步分析.  相似文献   

On the relations between the hydrological dynamical systems of water budget,travel time,response time and tracer concentrations     

Riccardo Rigon  Marialaura Bancheri 《水文研究》2021,35(1):e14007

Using previous results on extended Petri Nets (EPN), we present the relations between various hydrological dynamical systems (HDSys) derived from the water budget. Once the water budget has been implemented, there is a consistent way of getting the equations for backward travel time distributions, for forward response time distributions and for the concentration of a solute or tracer. We show that the water budget has a correspondence of one to many with the backward travel time distributions. In fact, to any one of the water budget equations there correspond as many equations as there are input precipitation events. The backward travel time distributions are related to the response time distributions by Niemi's relationship and, if there are n outputs, by the definition of n − 1 partition functions. These determine what fraction of the water volume injected into the control volume at a specific time t_in goes asymptotically to a specific output. Given the backward travel time distributions, the output concentration of a solute or tracer also depends on the input concentration. The paper clarifies the complicated relations described above by taking [Hydrology and Earth System Sciences, 20, 299–328] as an example from literature. Once the appropriate information is presented, it is shown how these HDSys can be solved simultaneously without duplicating calculations. Then, it is also shown that, under the hypothesis of uniform mixing of water ages within each reservoir, these systems can be solved exactly.  相似文献   

Climate change analysis on historical watershed‐scale precipitation by means of long‐term dynamical downscaling          下载免费PDF全文

《水文研究》2017,31(1):35-50

A methodology based on long‐term dynamical downscaling to analyse climate change effects on watershed‐scale precipitation during a historical period is proposed in this study. The reliability and applicability of the methodology were investigated based on the long‐term dynamical downscaling results. For an application of the proposed methodology, two study watersheds in Northern California were selected: the Upper Feather River watershed and the Yuba River watershed. Then, precipitation was reconstructed at 3‐km spatial resolution and hourly intervals over the study watersheds for 141 water years from 1 October 1871 to 30 September 2012 by dynamically downscaling a long‐term atmospheric reanalysis dataset, 20th century global reanalysis version 2 by means of a regional climate model. The reconstructed precipitation was compared against observed precipitation, in order to assess the applicability of the proposed methodology for the reconstruction of watershed‐scale precipitation and to validate this methodology. The validation shows that the reconstructed precipitation is in good agreement with observation data. Moreover, the differences between the reconstructed precipitation and the corresponding observations do not significantly change through the historical period. After the validation, climate change analysis was conducted based on the reconstructed precipitation. Through this analysis, it was found that basin‐average precipitation has increased significantly over both of the study watersheds during the historical period. An upward trend in monthly basin‐average precipitation is not significant in wet months except February while it is significant in dry months of the year. Furthermore, peak values of basin‐average precipitation are also on an upward trend over the study watersheds. The upward trend in peak basin‐average precipitation is more significant during a shorter duration. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

中国东部冬季降水的动力结合统计预测方法研究   总被引：1，自引：0，他引：1  

郎咸梅 《气象学报》2012,70(2):174-182

针对中国东部6个气候关键区,首先,通过相关分析指出,冬季降水既与前期气候因子有关,又受同期大气环流的影响。因此,有必要采用动力与统计相结合的方法进行气候预测研究。然后,从实时预测的角度出发,综合考虑前期预测因子的观测信息和具有数值可预测性的同期气候因子的数值模式结果,使用多元线性回归分析方法就各区域平均冬季降水逐一建立了短期气候预测模型,并在预测模型中考虑了模型结果中系统误差的订正。交叉检验分析结果表明,所建立的各区域预测模型普遍具有较好的预测效果,预测优势主要表现在对冬季降水的变化趋势、年际变化、以及异常符号的预测准确率上。就6个区域平均而言,1982—2008年交叉检验结果与实况间的相关系数和距平同号率分别为0.69和78%,表明该预测思想具有可行性。  相似文献   

GRAPES变分同化系统中动力平衡约束的统计求解   总被引：5，自引：1，他引：4       下载免费PDF全文

王瑞春  龚建东  张林 《应用气象学报》2012,23(2):129-138

该文在GRAPES (Global/Regional Assimilation and PrEdiction System) 模式面三维变分 (3D_Var) 框架中引入了一种描述不同控制变量之间动力平衡约束的新方案。新方案采用统计得到的流函数和模式气压变量 ( π ) 之间的回归系数代替原方案中的线性平衡方程,来表达旋转风和质量场之间的平衡关系;采用流函数和势函数之间的回归系数,补充表达了原方案中所没有的旋转风和散度风之间的平衡关系。与原方案相比,新方案算法简单,避免了垂直方向的反复插值,减少了插值误差的引入。通过随机扰动试验和单点试验可以发现,在地转关系成立较好的区域,新方案中旋转风和质量场的耦合程度与原方案接近一致;而在地转关系不适用区域,新方案可以有效减小两者的耦合程度。此外,由于新方案中添加了旋转风和散度风之间的动力平衡约束,边界层的风场分析也更加接近大气真实状况。  相似文献   

Using Action Research to Implement the National Geography Standards: Teachers as Researchers   总被引：1，自引：1，他引：0  

《The Journal of geography》2012,111(3):103-111

Abstract

Action research is defined as systematic classroom-based inquiry to solve teacher-perceived problems. It has been a component of education, particularly professional staff development, for the past century under several names although geography educators in the United States have rarely used it for this, or any other, purpose. This paper reviews the literature on action research in order to argue for its use in geography education. A preliminary exploration of action research-based professional staff development is described. The results of the project indicate that action research is potentially useful as a way to guide teachers to reflect on their practice. It is argued that geography educators should include it in their repertoire of reform techniques.  相似文献   

丹巴水电站引水隧洞地下水工程效应分析     

于静  张九灵  王晓欣 《地质灾害与环境保护》2009,20(2):41-46

丹巴水电站是大渡河干流水电规划“三库22级”的第8级电站,左右两条引水隧洞长10余公里,调查揭示沿线地下水丰富,本文即是通过对隧洞线泉水水样进行采样、水质分析结果讨论其对隧洞中的混凝土砌体的影响。结果表明隧洞经过区基岩地下水水质不会对衬砌混凝土造成不利的影响。只是佛爷崖断层带处地下水硫酸根离子含量较高,存在一定的酸性侵蚀作用。  相似文献