直至核幔边界的Mg2SiO4成分熔体剪切粘滞度的平衡分子动力学研究     

张毅刚  聂高众 《岩石学报》1998,14(4):409-418

熔体的粘滞度极大地影响熔体的各处动力学行为。虽然有一些有关酸碱生熔体粘滞度的数据但涉及地球更深部过程的基性和超基性熔体的粘滞度的数据很少。本项研究利用平衡分子动力学方法Ｍｇ２ＳｉＯ４成分熔体从２１６９Ｋ到５５９５Ｋ。压力从１０＾５Ｐａ到１３５ＧＰａ的粘滞度,所获得的粘滞度数据介于Ｕｒｂａｉｎｅｔ ａｌ,（１９８２）和Ｉｖａｎｏｖ ａｎｄ Ｓｔｅｎｇｅｌｍｅｙｅｒ（１９８２）的实验数据之间,比Ｓｈａ  相似文献   

明矾石合成4A沸石的试验研究   总被引：3，自引：0，他引：3  

朱继存 《化工矿产地质》1998,20(3):259-264

以明矾石矿为原料,成功地合成了物理化学性能较好的４Ａ沸石。通过对４Ａ沸石合成的基本原理、工艺条件和主要工作参数的研究,提供了合成４Ａ沸石的新途径,丰富了明矾石矿综合利用的新内容。  相似文献   

On the Occurrence of Silician Magnetites   总被引：2，自引：0，他引：2  

Hidehiko Shimazaki 《Resource Geology》1998,48(1):23-29

Abstract: About 120 specimens of magnetite from various localities are examined by an electron microprobe analyzer. Magnetites containing more than one weight percent of silica but lack of any other components than ferrous and ferric iron, called silician magnetites in the present paper, are recognized in 23 skarn, one vein and one thermally metamorphosed massive sulfide deposits. Thus it is confirmed that this mineral occurs in nature much more frequently than so far expected. Besides silician magnetites, magnetites with appreciable amounts of Al₂O₃, CaO, MgO and other components along with silica, are also recognized in some skarn deposits. Magnetites with such unusual compositions are found only in hydrothermal environments, and it is suggested that precipitation mechanisms seem to be responsible for their formation.
In silician magnetites, excess electric charge brought by the replacement of ferric iron in tetrahedral site by silicon, could be compensated by the replacement of ferric iron in octahedral site by ferrous iron, known as γ–Fe₂SiO₄ component. The natural occurrence of silician magnetites, however, gives no positive support to the existence of this component at crustal pressures. Instead a preliminary Mössbauer experiment demonstrates that one silician magnetite has a maghemite –like structure by the omission of ferrous iron from octahedral site.  相似文献   

Relationship of Water Chemistry to Serum ThyroidHormones in Captive Sharks with Goitres     

Gerald L. Crow  Marlin J. Atkinson  Benny Ron  Shannon Atkinson  Arleene D. K. Skillman  George T. F. Wong 《Aquatic Geochemistry》1998,4(3-4):469-480

Captive whitetip reef sharks, Triaenodon obesus,at Sea Life Park (SLP) Hawaii, Waimanalo, Hawaii develop goitre, whereas, T. obesus at the Waikiki Aquarium (WAQ), Honolulu,Hawaii do not develop goitre. To determine theeffects of natural concentrations of iodine on thereduction of goitre, two sharks from SLP with goitrewere placed in an enclosed coastal lagoon with naturalseawater. Using ultrasound measurements the twogoitres were initially 11.4 cm and 14.6 cm in depthand after 3 months decreased to 4.7 cm and 5.7 cm. Radioimmunoassay analysis of the thyroid hormoneT3 sera concentrations were initially 0.22 ng/mland 0.33 ng/ml and increased to 1.84 ng/ml after beingplaced in the lagoon. Sera T4 were initially0.93 ng/ml and 0.99 ng/ml and increased dramaticallyto 17 ng/ml and 56 ng/ml. Over the six month samplingperiod, two resident sharks in the lagoon with normalthyroids had sera T3 concentrations from 0.89ng/ml to 1.1 ng/ml, and sera T4 concentrationsfrom 3.1 ng/ml to 7.9 ng/ml. The hypothyroidcondition in the SLP goitred-sharks is likely linkedto the low environmental iodide (<0.005 M), andhigh nitrate (111 M) of SLP water. The WAQwell-water facility was characterized by anoxic waterwith high iodide (0.60 M), total iodine (1.90M), and typical nitrate (24.6 M)concentrations of interstitial groundwater. Thedifference of iodide concentration of SLP and WAQ tankwater (<0.005 M versus 0.60 M) wasdirectly related to the hydrogeology of the well-watersources. To avoid goitre in marine aquarium systems,we recommend maintaining iodide concentrations of atleast 0.15 M.  相似文献   

光波多普勒效应公式的3种推导     

蒲明刚  潘必凯 《成都信息工程学院学报》1998,(4)

给出光波多普勒效应的３种推导,并简述其重要意义。  相似文献   

Stratagem ^TM EH—4电导率成像系统简介及应用   总被引：18，自引：0，他引：18  

郭建强  武毅 《物探与化探》1998,22(6):458-464

ＥＨ－４电导率成像系统属于部分可控源与天然场源相结合的一种大地电磁测深系统。由接收与发射两部分组成。根据勘探目的,可选择高频配置或低频配置。通过采集时间域两组相互正交的电磁场信号经过频谱分析及运算,求得不同频率的电阻率,相位及相关度变化曲线。通过分析对比这些曲线,现场判别数据质量,同时对剖面测点的一维视电阻率连续反演结果进行ＥＭＡＰ二维连剖面反演,图示电阻率断面灰度图,可即时对勘测结果进行初步解释  相似文献   

Broad-band X-ray/γ-ray spectra and binary parameters of GX 339–4 and their astrophysical implications     

Andrzej A. Zdziarski  Juri Poutanen  Joanna Mikolajewska  Marek Gierli&#;ski  Ken Ebisawa  & W. Neil Johnson 《Monthly notices of the Royal Astronomical Society》1998,301(2):435-450

  相似文献   

Projection of the Future Changes in Tropical Cyclone Activity Affecting East Asia over the Western North Pacific Based on Multi-RegCM4 Simulations   总被引：1，自引：0，他引：1  

Jie WU  Xuejie GAO  Yingmo ZHU  Ying SHI  Filippo GIORGI 《大气科学进展》2022,39(2):284-303

Future changes in tropical cyclone(TC)activity over the western North Pacific(WNP)under the representative concentration pathway RCP4.5 are investigated based on a set of 21 st century climate change simulations over East Asia with the regional climate model RegCM4 driven by five global models.The RegCM4 reproduces the major features of the observed TC activity over the region in the present-day period of 1986-2005,although with the underestimation of the number of TC genesis and intensity.A low number of TCs making landfall over China is also simulated.By the end of the 21st century(2079-98),the annual mean frequency of TC genesis and occurrence is projected to increase over the WNP by16%and 10%,respectively.The increase in frequency of TC occurrence is in good agreement among the simulations,with the largest increase over the ocean surrounding Taiwan Island and to the south of Japan.The TCs tend to be stronger in the future compared to the present-day period of 1986-2005,with a large increase in the frequency of strong TCs.In addition,more TCs landings are projected over most of the China coast,with an increase of~18%over the whole Chinese territory.  相似文献   

RegCM4对华北区域21世纪气候变化预估研究     

陈颖  张冬峰  王林  刘月丽  王大勇 《干旱气象》2022,40(1):1-10

利用国家气候中心完成的RegCM4区域气候模式在RCP4.5和RCP8.5两种排放路径下的气候变化动力降尺度试验结果,在检验模式对基准期(1986—2005年)气温和降水模拟能力基础上,进行华北区域21世纪气候变化预估分析。结果表明:RegCM4对华北区域基准期气温和降水的模拟能力较好。未来21世纪,两种情景下华北区域气温、降水、持续干期(consecutive dry days, CDD)和强降水量(R95p)变化逐渐增大,但变化幅度在高排放的RCP8.5情景下更为显著,其中近期(2021—2035年)、中期(2046—2065年)、远期(2080—2098年)RCP8.5情景下年平均气温分别升高1.77、3.44、5.82℃,年平均降水分别增加8.1%、14%、19.3%,CDD分别减少3、3、12 d, R95p分别增加30.8%、41.9%、69.8%。空间上,未来21世纪华北区域内年、冬季、夏季平均气温将一致升高,夏季升温幅度最大;年、冬季、夏季平均降水整体以增加为主,冬季降水增加幅度最大;CDD以减少为主,但近期和中期在山西和京津冀有所增加,而R95p以增加为主,表明21世纪华北区域干旱事件逐渐减少、极端降水事件不断增加。  相似文献   

综合Span图和纹理特征的高分三号影像建筑区提取     

盛玉婷  赵争  王童童 《北京测绘》2020,(1):73-78

建筑区的识别和提取是城市环境规划与研究至关重要的工作。本文采用高分三号全极化SAR影像,提出了一种综合Span图和纹理特征的建筑区提取方法。首先基于Span图利用灰度共生矩阵算法提取图像的7种原始纹理特征,通过目视解译选择出4种纹理效果较好的统计量,然后利用主成分分析法去除他们之间的相关性,筛选出2个最佳纹理特征与Span图结合,最后对组合影像进行分类提取。本文将提取结果与综合灰度和纹理特征建筑区提取、无纹理特征提取方法结果进行对比,实验结果表明:本文方法提取建筑区边界轮廓更加清晰,精度可达92%,提取效果明显得到了优化。  相似文献