多圆柱区域上解析函数的Riemann—Hilbert边值问题     

王莉萍 《中国海洋大学学报(自然科学版)》1991,(3)

利用多复变函数的理论,证明多复变解析函数在多圆柱区域上标准形式的Riemann—Hibert边值问题可解的充要条件,并给出解的表示式,并利用解析变换,导出多复变解析函数的一般Riemann—Hilbert边值问题的可解性。  相似文献   

非线性波传播的新型数值模拟模型及其实验验证 引入变换速度变量   总被引：4，自引：0，他引：4  

张洪生  冯文静  商辉 《海洋学报》2007,29(5):161-173

以一种新型的含变换速度变量的Boussinesq型方程为控制方程组,采用五阶Runge-Kutta-England格式离散时间积分,采用七点差分格式离散空间导数,并采用恰当的出流边界条件,从而建立了非线性波传播的新型数值模拟模型.对均匀水深水域内波浪传播的数值模拟,说明在引入变换速度后进一步增大了模型的水深适用范围.对潜堤地形上波浪传播的数值模拟说明,在引入变换速度后进一步提高了模型的数值模拟精度.  相似文献   

CMIP6海洋模式比较计划（OMIP）概况与评述     

于子棚  林鹏飞  刘海龙  李逸文  王雅琦  孙志阔  杨茜  马金峰  靳江波  丁梦蓉  孟瑶 《气候变化研究进展》2019,15(5):503-509

海洋模式比较计划（OMIP）是第六次国际耦合模式比较计划（CMIP6）中的一个支撑子计划。OMIP致力于CMIP6中模式系统偏差来源及其影响这样一个重要科学问题。同时,OMIP也将在区域海平面变化和近期气候（未来10~30 a）或者年代际气候预测的相关科学问题上有重要贡献,这些问题被世界气候研究计划（WCRP）列为气候科学领域巨大挑战的科学问题。OMIP采用统一的大气外强迫数据集和通量计算方案,进行全球海洋-海冰耦合试验、示踪物试验以及生物地球化学循环试验。同时,OMIP提供了一套针对海洋变量的详细的诊断框架,这个框架既可以评估和改进模式模拟,也可以用于理解海洋-海冰过程在整个气候系统中的作用。  相似文献   

青海省天峻县疏勒河地区铜及多金属综合信息成矿预测          下载免费PDF全文

张文斌  张子鸣  杨延峰  郑德胜 《甘肃地质》2018,(1):43-50

研究区位于中—南祁连弧盆系中祁连岩浆弧区。区内以沉积地层分布最为广泛,地层时代跨度大,其中青白口系碎屑岩与碳酸盐岩组成的建造、奥陶系中基性火山喷出岩—碳酸盐岩—碎屑岩建造及二叠系碎屑岩系与成矿关系密切。区内断裂纵横交错,褶皱发育,总体构造线以NW、NWW向为主,近EW向、NNE、NNW向次之。区域岩浆活动主要表现在加里东期,岩浆从超基性—基性—中酸性—酸性都有不同程度的出露。区内主要成矿类型有岩浆热液型钨钼矿、砂岩型铜矿、中低温热液型铜矿及铅锌矿。本文从成矿地质背景分析入手,研究了与成矿有关的地质特征,应用MORPAS软件将研究区划分为3 km×3 km的单元格,提取变量,构置证据图层,计算单元找矿信息量,对研究区进行了铜及多金属矿的成矿预测,圈定并评价了6处找矿靶区,其中Ⅰ类靶区3处,Ⅱ类靶区3处。为该区今后部署铜、钨钼、铅锌等矿产勘查工作提供了重要依据,指出了进一步工作的方向。  相似文献   

不同初始瓦斯压力下煤体动力学特性及其劣化特征     

王磊  陈礼鹏  刘怀谦  朱传奇  李少波  范浩  张帅  王安铖 《岩土力学》2023,44(1):144-158

为探究不同初始瓦斯压力下煤体动力学特性及其劣化规律,利用自主研发的含瓦斯煤岩动静组合加载试验系统对含瓦斯煤开展冲击压缩试验,结合CT扫描系统分析了含瓦斯煤内部裂隙的扩展演化规律,并基于不同初始瓦斯压力下冲击煤样内部裂隙率增量定量表征了其细观损伤程度,探讨了冲击荷载作用下含瓦斯煤宏观力学参量劣化规律。研究结果表明：（1）冲击荷载作用下含瓦斯煤动态应力-应变曲线无明显压密阶段,分为线弹性阶段、塑性硬化阶段和破坏阶段,并发现随初始瓦斯压力升高,冲击煤样峰值强度、峰值应变和弹性模量均出现弱化现象;（2）瓦斯加剧了煤体内部裂隙的扩展和贯通,并根据CT扫描结果发现,含瓦斯煤冲击破坏模式主要以劈裂和层裂破坏为主,随初始瓦斯压力升高,两种破坏模式越显著,煤体内部裂隙数量及其损伤程度逐渐增大,空间裂隙网络更为复杂;（3）基于细观层面定义了损伤变量,得其值随初始瓦斯压力升高呈现二次函数上升,对比冲击载荷作用下煤体动态强度与以裂隙率增量定义损伤程度所得理论强度,验证了细观层面煤体裂隙率增量定义损伤变量的合理性,建立了含瓦斯煤细观劣化与宏观参量损失的内在联系。研究成果丰富了含瓦斯煤动力学基础理论,为矿井煤岩瓦...  相似文献   

A model for gas pressure in layered landfills with horizontal gas collection systems     

《Computers and Geotechnics》2015

The recovery and emission of landfill gas (LFG) is an important topic in landfill management. To produce an effective engineering design for an LFG collection system, designers must understand the migration of gas from the waste body to horizontal extraction wells. This paper develops a two-dimensional analytical solution to enable the study of the gas pressure distribution, well pressure and recovery efficiency in layered landfills with horizontal wells. A horizontal layered structure is used to accommodate the non-homogeneity of various municipal solid waste (MSW) aspects with respect to depth, including gas generation, permeability and temperature. The governing equations, subject to boundary and continuity conditions, are solved by using separation of variables and double finite integral transforms. The solution was verified against another analytical solution and a numerical simulation. Subsequently, a sensitivity analysis of single-well model parameters is performed to optimize a double-well system. The results show that a landfill with horizontal collection systems cannot be assumed to be one dimensional with increasing well spacing. Additionally, both the operational vacuum and maximum gas pressure can be reduced through the design of a double- or multiple-well system. Therefore, the proposed solution can be used for the verification of more complex models and the preliminary design of a horizontal well system.  相似文献   

Inter-decadal Variability of the East Asian Summer Monsoon and Its Impact on Hydrologic Variables in the Haihe River Basin,China     

LI Fuxing  ZHANG Shiyan  CHEN Dong  HE Li  GU Leilei 《资源与生态学报(英文版)》2017,8(2):174-184

Wavelet analysis and Mann-Kendall tests are employed to evaluate the variation in the East Asian summer monsoon (EASM) and hydrological variables in the Haihe River basin calculated by the Variable Infiltration Capacity model. The relationships between those variables and the EASM are also examined. The results indicate consistent 40a periodic variation in both the hydrological variables and the EASM. The hydrologic variables show downward trends in the Haihe River basin over the past 60 years, especially in piedmont regions of the Taihang-Yan Mountains. The variables are closely related to the EASM, whose continuous weakening since the 1970 s has resulted in prolonged drought and severe water shortages in the basin. The periodicity of the EASM index was analyzed using continuous wavelet transform methods. We found the most significant periodic signal of the EASM is ~80 years; therefore, the EASM may reinforce and reach a maximum in the 2040 s, resulting in more precipitation and other impacts on basin water resources. Hydrologic variables in the basin in the 2040 s are predicted, and their spatial distributions in the Haihe River basin are also discussed. These results allow for the estimation of water resources under forecasted EASM, which will be useful for water resources management in the Haihe River basin.  相似文献   

Estimating reference evapotranspiration using numerical weather modelling   总被引：3，自引：0，他引：3  

Asnor Muizan Ishak  Michaela Bray  Renji Remesan  Dawei Han 《水文研究》2010,24(24):3490-3509

Evapotranspiration is an important hydrological process and its estimation usually needs measurements of many weather variables such as atmospheric pressure, wind speed, air temperature, net radiation and relative humidity. Those weather variables are not easily obtainable from in situ measurements in practical water resources projects. This study explored a potential application of downscaled global reanalysis weather data using mesoscale modelling system 5 (MM5). The MM5 is able to downscale the global data down to much finer resolutions in space and time for use in hydrological investigations. In this study, the ERA‐40 reanalysis data are downscaled to the Brue catchment in southwest England. The results are compared with the observation data. Among the studied weather variables, atmospheric pressure could be derived very accurately with less than 0·2% error. On the other hand, the error in wind speed is about 200–400%. The errors in other weather variables are air temperature (<10%), relative humidity (5–21%) and net radiation (4–23%). The downscaling process generally improves the data quality (except wind speed) and provides higher data resolution in comparison with the original reanalysis data. The evapotranspiration values estimated from the downscaled data are significantly overestimated across all the seasons (27–46%) based on the FAO Penman–Monteith equation. The dominant weather variables are net radiation (during the warm period) and relative humidity (during the cold period). There are clear patterns among some weather variables and they could be used to correct the biases in the downscaled data from either short‐term in situ measurements or through regionalization from surrounding weather stations. Artificial intelligence tools could be used to map the downscaled data directly into evapotranspiration or even river runoff if rainfall data are available. This study provides hydrologists with valuable information on downscaled weather variables and further exploration of this potentially valuable data source by the hydrological community should be encouraged. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

双标量损伤模型及其在Biot固结有限元中的应用   总被引：1，自引：1，他引：0  

薛新华  张我华 《岩土力学》2010,31(1):20-26

在前人工作的基础上,推广并发展了各向同性双标量损伤变量理论,推导出双标量损伤变量模型的损伤演化方程。然后,将其引入比奥固结有限元方程中,并据此编制相应的双标量损伤变量流-固耦合有限元程序。最后,对一个软土路基有限元简化模型进行分析计算,并以典型节点为例,绘制了模型沉降值、孔压值、损伤变量等的变化曲线。结果表明,利用双标量损伤变量模型描述土的本构关系比单标量损伤模型更加合理。  相似文献   

An eclipse of the X-ray flux from the dwarf nova OY Carinae in quiescence     

Gabriel W. Pratt  B. J. M. Hassall  T. Naylor  Janet H. Wood 《Monthly notices of the Royal Astronomical Society》1999,307(2):413-419

We present a phase-resolved ROSAT HRI X-ray light curve of the dwarf nova OY Car in quiescence. The X-ray flux is eclipsed at the same time as the optical eclipse of the primary, and the region of X-ray emission is comparable in size to the white dwarf. We use subsequent optical observations to update the orbital ephemeris of the system.  相似文献