TWO－DIMENSIONAL　MATHEMATICAL　MODEL　FOR　STUDYING　EROSION　AND　SEDIMENTATION　OF　A　WANDERING　STRETCH　IN　THE　LOWER　YELLOW　RIVER   总被引：1，自引：0，他引：1  

ZHANG Shiqir 《国际泥沙研究》1994,(3)

ＴＷＯ－ＤＩＭＥＮＳＩＯＮＡＬＭＡＴＨＥＭＡＴＩＣＡＬＭＯＤＥＬＦＯＲＳＴＵＤＹＩＮＧＥＲＯＳＩＯＮＡＮＤＳＥＤＩＭＥＮＴＡＴＩＯＮＯＦＡＷＡＮＤＥＲＩＮＧＳＴＲＥＴＣＨＩＮＴＨＥＬＯＷＥＲＹＥＬＬＯＷＲＩＶＥＲ￥ＺＨＡＮＧＳｈｉｑｉｒ（Ｓｅｎｉｏｒ...  相似文献   

BANDPASS FILTERING ANALYSIS WITH GAUSSIAN WEIGHTING FUNCTION IN TWO-DIMENSIONAL FIELDS          下载免费PDF全文

He Xicheng  Wan Qilin 《Acta Meteorologica Sinica》1994,8(1):109-116

This paper examines the response of the bandpass filter with Gaussian weighting function to arbitrarytwo-dimensional fields and proposes a new concept of relative response function.Based on the properties of relative re-sponse function,satisfactory weighting parameters C_1 and C_2 are obtained.By studying two cases,the procedure of us-ing structure function curves to choose the maximum response wavelength is formulated.It is shown that bandpass fil-tering offers some improvements to the analysis and forecast of mesoscale weather processes.  相似文献   

盆地烃类运移二维二相流动数学模型分析与应用实例   总被引：5，自引：1，他引：5       下载免费PDF全文

陶一川  姜鹏 《地球科学》1995,20(3):314-321

从地质固体系统与流体系统相互作用所形成的能量流、物质流的观点，系统地论述了建立烃类运移主要控制方程，即烃水两相拉格朗日型异常地层压力方程和饱和度方程，研制了开发了烃类运移数值模拟系统，阐明了该耦合系统的要素功能和求解方法，提供了改善系统模拟精度的措施，最后介绍了该模拟系统在松辽盆地东南隆起某测线的应用实例。  相似文献   

用剩余信息量最小准则实现直流电测深数据的二维自动反演     

沈金松 《物探化探计算技术》2002,24(1):46-53

自Pelton等发表第一篇直接电测深数据的二维反演文章以来，电测深数据的二维反演解释已广泛应用于资源勘探和环境监测，并取得一定效果。然而，由于该方法中加入了人为确定的平滑约束，其反演解释结果具有很大不确定性，使其在实际生产中普及应用受到限制。因此，如何在现有方法的基础上进一步改进完善成为该方法普及应用的关键。为了使反演解释结果既忠于实测数据，又合理地反映地下介质的变化，作者在本文中讨论了基于最大熵谱原理的剩余信息量最小准则实现电测深数据的二维自动反演。作者在文中还介绍了正演计算和偏导数求取中，提高精度和计算效率的技巧。用三个数值模式算例对本文的自动反演方法进行了验证。数值模拟结果表明，基于剩余信息量电小准则的二维自动反演给出的解释结果基本不受人为因素影响，能反映地下介质电阻率的详细变化。  相似文献   

大气中一氧化碳浓度变化的模拟研究   总被引：4，自引：1，他引：4  

张仁健  王明星 《大气科学》2001,25(6):847-855

应用全球二维大气化学模式,模拟了CO、CH4和OH自由基等成分自工业革命到2020年的长期变化.模拟的全球CO平均体积分数在1840年、1991年和2020年分别为27×10-6、76×10-6和105×10-6.从1840到1991年,OH自由基数浓度从7.17×105个分子/cm3下降到5.79×105个分子/cm3,降低了19%.模拟的CH4长期变化与冰芯资料相符.模拟的20世纪80年代CO体积分数年增长率为1.03%～1.06%.大气中CO在20世纪90年代前是增长的,而到90年代初观测到CO体积分数突然下降.应用二维大气化学模式对此原因进行了模拟研究,结果表明,CO排放源的减少是CO体积分数下降的主要因子,平流层臭氧减少是另一个重要因子.尽管CO排放源的减少对大气CH4增长率的变化有较大影响,而CH4排放源减少对CO体积分数变化却几乎没有影响.  相似文献   

NUMERICAL SIMULATION OF ATMOSPHERIC METHANE TRENDS OVER THE LAST 150 YEARS     

张仁健  王明星 《Acta Meteorologica Sinica》2001,(1)

A global two-dimensional chemistry model is developed to study long-term trends of CH_4 sinceindustrial revolution.The sources of CH_4,CO and NO_x are parameterized as functions of latitudeand time.With two long-term emission scenarios,long-term trends of CH_4 are simulated.The resultshave a good agreement with observation from ice cores.The modeled CH_4 increased from 760 ppbvin 1840 to 1611.9 ppbv in 1991, while the modeled number concentration of tropospheric OHdecreased from 7.17×10~5 cm~(-3)in 1840 to 5.79×10~5 cm~(-3) in 1991.The increase of atmosphericCH_4 can be explained by the increase of emission of CH_4 and build-up because of decrease of OHradicals that remove CH_4 from the atmosphere.The model is also used to simulate the distribution of CH_4.Comparisons between the modelresults and observations show that the model can simulate both latitudinal distribution and seasonalvariation of CH_4 well.  相似文献   

NUMERICAL SIMULATION OF ATMOSPHERIC METHANE TRENDS OVER THE LAST 150 YEARS^*     

ZHANG Renjian  WANG Mingxing 《Acta Meteorologica Sinica》2001,15(1):12-20

A global two-dimensional chemistry model is developed to study long-term trends of CH₄ since industrial revolution.The sources of CH₄,CO and NO_x are parameterized as functions of latitude and time.With two long-term emission scenarios,long-term trends of CH₄ are simulated.The results have a good agreement with observation from ice cores.The modeled CH₄ increased from 760 ppbv in 1840 to 1611.9 ppbv in 1991, while the modeled number concentration of tropospheric OH decreased from 7.17×10⁵ cm^-3 in 1840 to 5.79×10⁵ cm^-3 in 1991.The increase of atmospheric CH₄ can be explained by the increase of emission of CH₄ and build-up because of decrease of OH radicals that remove CH₄ from the atmosphere.The model is also used to simulate the distribution of CH₄.Comparisons between the model results and observations show that the model can simulate both latitudinal distribution and seasonal variation of CH₄ well.  相似文献   

溶胶－凝胶方法制取纳米级超导物质的研究     

高京林 《现代地质》1996,10(3):360-364

当前对超导物质的研究都集中于高临界温度的超薄型物质的研究上，本研究通过相对简单的方法获得高纯度的纳米级的钙钛矿型超导物质，其过程为：通过溶胶－凝胶方法合成一种含有Ｌａ和Ｎｉ的高纯度的有机物，然后利用天然蒙脱石的离子交换性将上述化合物渗入到其含水层中以获得超薄型的超导物质  相似文献   

Absorption of Arsenite on Several Iron （Hydro-）Oxides and Impact from Pre-processing Methods     

YE Ying JI Shanshan WU Daidai LI Jun ZHANG Weirui 《《地质学报》英文版》2006,80(2):200-205

The absorption reactions of arsenite on Fe （hydro-）oxides are studied. The three absorbent types are Fe（OH）3 gel and two Fe （hydro-）oxides, in which the Fe（OH）3 gel was dried in a microwave oven under vacuum at 80℃. It is found that pH changes from 9.71 to 10.36 in 6 minutes after the Fe （OH）3 gel was mixed with NaAsO2 solution, as the arsenite replaces the OH- in goethite and Fe（OH）3. At the 40th minute after the start of the reaction, pH decreases, which is most probably because that the monodentate surface complex of absorbed arsenite has changed into mononuclear-bidentate complex and released proton. The decline in pH values indicates not the end of the absorption but a change in the reaction type. Temperature and dissolved gas has little effect on these two types of reactions. The total absorption of arsenite increases after the absorbent is irradiated with ultrasound, which also lead to difficulty in separating the solids from solution. The absorption capacity for arsenite of Fe（OH）3 gel dried in a microwave oven under vacuum is 53.18% and 17.22% respectively better than that of Fe （OH）3 gel and gel dried at 80℃. The possible reasons are that the water molecules in the gel vibrates with high frequency under the effect of microwave irradiation, thereby producing higher porosity and improved surface activity.  相似文献   

蒙脱石层电荷与有机改性蒙脱石凝胶性能关系研究   总被引：2，自引：2，他引：2  

邱俊  陈平  张言贵  吕宪俊 《矿物岩石》2007,27(1):36-39

利用自然沉降法提取了山东两不同产地膨润土中的钙基蒙脱石矿物M1和M2,利用结构式推算法计算了两提纯蒙脱石的层电荷:M1单位半晶胞的层电荷为0.38,M2单位半晶胞的层电荷为0.59;利用十八烷基三甲基氯化铵对蒙脱石进行有机改性,并对有机蒙脱石凝胶性能和层电荷的相关关系进行研究。研究发现:蒙脱石单位半晶胞的层电荷越低,在水中的分散性越好,越有利于十八烷基三甲基铵阳离子的插层,相应有机改性蒙脱石在二甲苯和乙醇体系中的凝胶性能越好(如M1);蒙脱石单位半晶胞的层电荷越高,在水中的分散性越差,越不利于十八烷基三甲基铵阳离子的插层,相应有机改性蒙脱石产品的凝胶性能较差(如M2)。  相似文献