Sr对6A02铝合金组织和性能的影响          下载免费PDF全文

杨占寿 《盐湖研究》2020,28(2):50-55

通过电磁感应炉制备了含锶6A02铝合金,对制备的试样采用OM、XRD、硬度测试、拉伸测试,研究Sr含量对6A02铝合金组织和性能的影响。结果表明Sr元素的加入可以细化合金的铸态组织,改变组织形貌。当Sr含量为0.5%时,细化效果最好,合金其力学性能最优。随着Sr含量的增加,6A02铝合金出现新相Al_4Sr,随着组织中Al_4Sr相增多,Mg_2Si相的析出减少,减弱了对合金的强化效果,合金的力学性能呈下降趋势。  相似文献   

Hydrodynamic derivative determination based on CFD and motion simulation for a tow-fish     

《Applied Ocean Research》2019

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温度、质量浓度对富氟流体中Hf高温高压水解行为的影响     

刘军锋  黄建军  李震  刘晓文  丁兴 《地球科学与环境学报》2019,(3):327-331

Hf是一种高场强元素,在地壳中的丰度较低,往往以类质同象的形式进入锆石中。以氟铪酸钾(K_2HfF_6)络合物为研究对象,观察它们在富水热液中的水解程度,进而研究Hf元素在地质过程中的迁移行为。结果表明:K_2HfF_6络合物在热液条件下能发生一定程度的水解反应,总体趋势为络合物的初始质量浓度越低且反应的温度越高,其水解程度越剧烈,络合物的稳定性也就越低;获得了高温高压条件下K_2HfF_6络合物的累积水解平衡常数。同时运用实验模拟的方法,根据提取液中Hf元素含量来推测矿物结晶时富氟流体中Hf元素含量,若以K_2HfF_6络合物最高配位的离子团形迁移时,Hf与F元素之间的质量浓度比值为1.6,据此可以计算成矿流体所需的最小F元素含量。  相似文献   

CX-6(02)微纳卫星超分辨率成像   总被引：1，自引：0，他引：1  

谭政  相里斌  吕群波  孙建颖  李平付  高爽  尹增山 《遥感学报》2019,23(2):196-204

面向微纳卫星高分辨率对地遥感,将超分辨率成像应用于中国整星60公斤级的CX-6(02)微纳卫星设计中,解决因体积和重量限制导致传统长焦距、大口径成像载荷无法应用于微纳卫星的问题。图像获取上,采用高帧频面阵CMOS探测器对同一地物目标多次曝光的方式,利用卫星姿态控制偏差和地速补偿来获得多帧具有亚像元位移的图像;超分辨率重建算法上,在变分贝叶斯框架下提出加权双向差分模型,提高先验概率模型的方向约束性,削弱观测方程求解的病态性。CX-6(02)星成像数据实验结果表明,本文的图像采样方法可获得较为充分的亚像元信息;相比传统的L1范数先验和全变分先验的变分贝叶斯超分辨算法重建结果,本文重建结果对反卷积运算导致的噪声放大具有更好的抑制作用,可获得两倍分辨率提升,有效提高数据质量和应用价值。  相似文献   

Vegetation species mapping in a coastal-dune ecosystem using high resolution satellite imagery     

Anabella Medina Machín  Javier Marcello  Antonio I. Hernández-Cordero  Javier Martín Abasolo  Francisco Eugenio 《地理信息系统科学与遥感》2019,56(2):210-232

Vegetation mapping is a priority when managing natural protected areas. In this context, very high resolution satellite remote sensing data can be fundamental in providing accurate vegetation cartography at species level. In this work, a complete processing methodology has been developed and validated in a complex vulnerable coastal-dune ecosystem. Specifically, the analysis has been carried out using WorldView-2 imagery, which offers spatial and spectral resolutions. A thorough assessment of 5 atmospheric correction models has been performed using real reflectance measures from a field radiometry campaign. To select the classification methodology, different strategies have been evaluated, including additional spectral (23 vegetation indices) and spatial (4 texture parameters) information to the multispectral bands. Likewise, the application of linear unmixing techniques has been tested and abundance maps of each plant species have been generated using the library of spectral signatures recorded during the campaign. After the analysis conducted, a new methodology has been proposed based on the use of the 6S atmospheric model and the Support Vector Machine classification algorithm applied to a combination of different spectral and spatial input data. Specifically, an overall accuracy of 88,03% was achieved combining the corrected multispectral bands plus a vegetation index (MSAVI2) and texture information (variance of the first principal component). Furthermore, the methodology has been validated by photointerpretation and 3 plant species achieve significant accuracy: Tamarix canariensis (94,9%), Juncus acutus (85,7%) and Launaea arborescens (62,4%). Finally, the classified procedure comparing maps for different seasons has also shown robustness to changes in the phenological state of the vegetation.  相似文献   

Process-based model for nearshore hydrodynamics, sediment transport and morphological evolution in the surf and swash zones     

R. Bakhtyar  A. Ghaheri  A. Yeganeh-Bakhtiary  D.A. Barry 《Applied Ocean Research》2009,31(1):44-56

Hydrodynamics and sediment transport in the nearshore zone were modeled numerically taking into account turbulent unsteady flow. The flow field was computed using the Reynolds Averaged Navier–Stokes equations with a k–ε turbulence closure model, while the free surface was tracked using the Volume-Of-Fluid technique. This hydrodynamical model was supplemented with a cross-shore sediment transport formula to calculate profile changes and sediment transport in the surf and swash zones. Based on the numerical solutions, flow characteristics and the effects of breaking waves on sediment transport were studied. The main characteristic of breaking waves, i.e. the instantaneous sediment transport rate, was investigated numerically, as was the spatial distribution of time-averaged sediment transport rates for different grain sizes. The analysis included an evaluation of different values of the wave friction factor and an empirical constant characterizing the uprush and backwash. It was found that the uprush induces a larger instantaneous transport rate than the backwash, indicating that the uprush is more important for sediment transport than the backwash. The results of the present model are in reasonable agreement with other numerical and physical models of nearshore hydrodynamics. The model was found to predict well cross-shore sediment transport and thus it provides a tool for predicting beach morphology change.  相似文献   

CAMS-CSM模式及其参与CMIP6的方案     

容新尧  李建  陈昊明  辛羽飞  苏京志  华莉娟  张正秋 《气候变化研究进展》2019,15(5):540-544

世界气候研究计划(WCRP)组织开展的耦合模式比较计划已实施到第六阶段（CMIP6),中国气象科学研究院发展的气候系统模式CAMS-CSM是注册参加CMIP6的模式之一。除CMIP6要求的气候诊断、评估和描述试验（DECK）以及历史气候模拟试验（Historical）外,CAMS-CSM还计划参加情景模式比较计划（ScenarioMIP)、云反馈模式比较计划（CFMIP)、全球季风模式比较计划（GMMIP）和高分辨率模式比较计划（HighResMIP)这4个模式比较子计划（MIPs)。文中通过介绍CAMS-CSM的基本情况和模拟性能,以及计划参加的CMIP6试验及MIPs,为模式试验数据使用者提供参考。  相似文献   

CMIP6高分辨率模式比较计划（HighResMIP）概况与评述     

王磊  包庆  何编 《气候变化研究进展》2019,15(5):498-502

高分辨率模式比较计划(HighResMIP)是第六次国际耦合模式比较计划(CMIP6)的新增计划,旨在研究水平分辨率提高后对气候模式模拟性能的改进,并借助多模式集合的方法降低模拟的不确定性。中国有5个模式团队在CMIP6 GitHub上注册参加HighResMIP。文中对HighResMIP的科学背景、试验设计和参与模式等方面进行了简要介绍,为需要了解该计划的科研人员提供参考。  相似文献   

FIO-ESM v2.0模式及其参与CMIP6的方案     

宋振亚  鲍颖  乔方利 《气候变化研究进展》2019,15(5):558-565

目前,世界气候研究计划（WCRP）组织的国际耦合模式比较计划（CMIP）已经进入到第六阶段（CMIP6),CMIP6试验的开展也已成为国内外地球系统模式工作组的首要工作之一。自然资源部第一海洋研究所地球系统模式FIO-ESM是以耦合自主开发的海浪模式为特色的地球系统模式。在参与CMIP5的FIO-ESM v1.0的基础上,通过升级分量模式、改进海气通量相关物理过程和提高分辨率等,FIO-ESM v2.0现已完成研发,正在开展CMIP6科学计划的相关试验。文中围绕FIO-ESM v2.0的特色和计划参与CMIP6的情况,介绍了FIO-ESM v2.0的模式框架、包含的特色物理过程以及拟参加的CMIP6科学计划情况,以方便气候研究领域的科学家了解和使用。  相似文献   

CMIP6二氧化碳移除模式比较计划（CDRMIP）概况与评述     

纪多颖  张倩  骆祉丞  陈扬馨 《气候变化研究进展》2019,15(5):457-464

地球工程是指通过人工方法在大规模尺度上干预气候系统,使地球气候降温的一种手段。CO₂移除是地球工程的主要途径之一。文中概述了CO₂移除地球工程的科学背景、各种CO₂移除方法的利弊、大尺度应用CO₂移除方法可能产生的气候效应和风险,以及CO₂移除方案在未来气候情景研究中的现状。在第六次国际耦合模式比较计划（CMIP6）框架下开展的CO₂移除模式比较计划（CDRMIP),为深入研究CO₂移除地球工程减缓气候变化的效能和气候系统对其的响应提供了统一试验方案和平台。CDRMIP的开展,对地球工程和气候变化研究具有重要的促进作用。  相似文献