Hydropower – A Green Energy? Tropical Reservoirs and Greenhouse Gas Emissions     

Günter Gunkel 《洁净——土壤、空气、水》2009,37(9):726-734

Reservoirs are man‐made lakes that severely impact on river ecosystems, and in addition, the new lake ecosystem can be damaged by several processes. Thus, the benefits of a reservoir, including energy production and flood control, must be measured against their impact on nature. New investigations point out that shallow and tropical reservoirs have high emission rates of the greenhouse gases CO₂ and CH₄. The methane emissions contribute strongly to climate change because CH₄ has a 25 times higher global warming potential than CO₂. The pathways for its production include ebullition, diffuse emission via the water‐air interface, and degassing in turbines and downstream of the reservoir in the spillway and the initial river stretch. Greenhouse gas emissions are promoted by a eutrophic state of the reservoir, and, with higher trophic levels, anaerobic conditions occur with the emission of CH₄. This means that a qualitative and quantitative jump in greenhouse gas emissions takes place. Available data from Petit Saut, French Guinea, provides a first quantification of these pathways. A simple evaluation of the global warming potential of a reservoir can be undertaken using the energy density, the ratio of the reservoir surface and the hydropower capacity; this parameter is mainly determined by the reservoir's morphometry but not by the hydropower capacity. Energy densities of some reservoirs are given and it is clearly seen that some reservoirs have a global warming potential higher than that of coal use for energy production.  相似文献   

Application of EDA technology and μClinux operating system in the earthquake precursor instruments          下载免费PDF全文

Anhua He  Gang Zhao  Na Xue  Jun Wang  Bailin Guo  Miaoxi Guo  Zizhong Fu 《地震科学（英文版）》2009,22(1):101-106

Using Altera's Quartus Ⅱ, Nios Ⅱ IDE and Sopc Builder development tools, the proton precession magnetometer principle host hardware platform is designed in a cyclone Ⅱ series FPGA chip (EP2C35). The proton precession magnetometer principle host core circuit's single-chip system-logic design is achieved by building and configuring the Nios Ⅱ soft-core processor, developing the IO interface and sensor control circuits, programming some hardware units' VHDL code, for example the equal precision cymometer and the DPLL. Through researching the embedded operating system configuration technology and building the NIOS Ⅱ soft-core processor's μClinux cross-compile environment, the μClinux system is transplanted to the NIOS Ⅱ environment. Another important task is writing the device drivers' and user programs' code. Through these work, the design realize the host function and achieve the expected target.

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开发地震技术及进展   总被引：1，自引：0，他引：1  

冯魁  张晓帆  陈川  冯新生 《地质与资源》2009,18(1):64-69

地震技术经过多年的发展,已经成为寻找石油和天然气的重要手段.并且正逐步向油气开发及生产领域渗透.出现的新技术主要包括：3D地震、垂直地震剖面、井间地震、时间推移地震、多波多分量地震、微地震检测、随钻地震等新技术.这些技术在国内各油田日益受到重视,在应用中取得了较好效果,为油田增储上产做出了重要贡献.对地震技术的形成过程作了简单回顾并着重对开发地震技术进行了介绍和归纳,同时对今后的发展方向进行了探讨.  相似文献   

四分量钻孔应变观测资料的换算和使用   总被引：6，自引：0，他引：6  

邱泽华  阚宝祥  唐磊 《地震》2009,29(4)

水平四分量钻孔应变仪观测的是地表附近一点的水平应变变化. 但是其直接记录并非应变变化,应根据互检条件先进行实地相对标定(计算元件校正系数),然后用理论固体潮进行实地绝对标定(计算探头校正系数),才能进行应变换算,给出可作为应变变化使用的数据. 因为钻孔应变仪观测的是应变变化,所以实地标定和应变换算都需要用增量. 对于精确的研究,这些校正系数都可能随时间变化,因而需要根据具体问题按特定时间段对校正系数进行计算. 该文比较系统地说明了四分量钻孔应变观测资料换算和使用的基本步骤和具体方法,并以姑咱台的观测资料为例,给出了具体分析结果.  相似文献   

利用EH4、GDP-32Ⅱ预测内蒙新民煤田煤系地层空间特征   总被引：7，自引：5，他引：2       下载免费PDF全文

张作伦  曾庆栋  于昌明  叶杰  刘建明  刘红涛  孙兴国  张瑞斌  覃锋  陈伟军 《地球物理学进展》2009,24(1)

目标勘查区煤层赋存规律不清,难以通过地表调查和常规的技术方法准确搞清煤系地层控制因素、空间位置、形态等重要参数,本文采用EH4电导率成像系统、GDP-32Ⅱ多功能电测系统,结合亚米级差分GPS开展测量,针对研究区地质特征,结合研究区物探异常特殊形态,预测了研究区可能的煤系地层空间分布,研究区煤系地层EH4测量电阻率具有较低特点(100～300Ωm)、GDP-32Ⅱ激电测量具有明显高充电率特点(最高可达38%),为下一步研究工作及工程验证提供指导.实践证明,采用EH4、GDP-32Ⅱ能够高精度预测煤系地层的空间分布特征,值得推广.  相似文献   

Demons算法在四维CT图像配准中的应用   总被引：1，自引：0，他引：1  

周付根  段卓镭 《CT理论与应用研究》2009,18(1):69-75

由呼吸运动引起的器官的运动及形变是4D精确放射治疗中最主要的误差来源。利用4D CT图像和配准技术来分析不同呼吸时相中组织、器官的形变是目前研究的热点。目前常用的研究方法是基于形变模型的3D配准算法。基于光流场的Demons算法具有速度快和精度高的特点,本文将其应用到4D CT图像配准中,并在原始图像形变力的计算中引入了对称梯度。实验结果表明,结合对称梯度的Demons方法具有更快的收敛速度,而且匹配误差小。  相似文献   

基于弥散-黏滞型波动方程的地震波衰减及延迟分析   总被引：3，自引：1，他引：2       下载免费PDF全文

尹陈  贺振华  黄德济 《地球物理学报》2009,52(1):187-192

地震波的衰减、储层中的流体预测和4D流体监测技术是目前石油地球物理勘探领域十分有价值的热门研究课题.该文在基于一维弥散-黏滞型波动方程正演的基础上,根据含流体地层的弥散性与黏滞性,研究和模拟含流体地层对地震波的吸收衰减特征、低频伴影现象及其在流体预测中的应用;同时,模拟和分析了地震波在含流体地层中传播而导致的延迟特征.这些特征的检测与解释方法,为基于实际地震资料的储层流体预测及4D油气田开发监测提供技术思路与有效方法.  相似文献   

Physical constraints on c13 and δ for transversely isotropic hydrocarbon source rocks          下载免费PDF全文

Fuyong Yan  De‐Hua Han  Qiuliang Yao 《Geophysical Prospecting》2016,64(6):1524-1536

Based on the theory of anisotropic elasticity and observation of static mechanic measurement of transversely isotropic hydrocarbon source rocks or rock‐like materials, we reasoned that one of the three principal Poisson's ratios of transversely isotropic hydrocarbon source rocks should always be greater than the other two and they should be generally positive. From these relations, we derived tight physical constraints on c₁₃, Thomsen parameter δ, and anellipticity parameter η. Some of the published data from laboratory velocity anisotropy measurement are lying outside of the constraints. We analysed that they are primarily caused by substantial uncertainty associated with the oblique velocity measurement. These physical constraints will be useful for our understanding of Thomsen parameter δ, data quality checking, and predicting δ from measurements perpendicular and parallel to the symmetrical axis of transversely isotropic medium. The physical constraints should also have potential application in anisotropic seismic data processing.  相似文献   

Modal identification of a centrifuge soil model using subspace state space method     

《Soil Dynamics and Earthquake Engineering》2016

In this paper, modal parameters of a layered soil system comprising of a soft clay layer overlying a dense sand layer are identified from accelerometer recordings in a centrifuge test. For the first time, the subspace state space system identification (4SID) method was employed to identify the natural frequencies, damping ratios, and complex valued mode shapes while considering the non-proportional damping in a soil system. A brief review of system identification concepts needed for application of the 4SID techniques to structural modal identification is provided in the paper. The identified natural frequencies were validated against those estimated by transfer function spectra. The computed normal mode shapes were compared with closed-form solutions obtained from the one-dimensional shear wave propagation equation. The identified modal parameters were then employed to synthesize state space prediction models which were subsequently used to simulate the soil response to three successive base motions. The identified models captured acceleration time-histories and corresponding Fourier spectra reasonably well in the small and moderate shaking events. In the stronger third shaking event, the model performed well at greater soil depths, but was less accurate near the surface where nonlinearities dominated.  相似文献   

地磁房湿度对地磁观测的影响及解决方案     

郅红魁  程楠  耿淑芬  郭慧  马志勇  驰源  宋建锁 《中国地震研究》2016,30(2):264-270

地磁房湿度变化较快或过大都易引起地磁数据的异常变化,且室内湿度不易控制,地磁房、磁通门磁力仪探头湿度智能在线分析监控系统,可以实时显示监控地磁房、磁通门磁力仪探头湿度的变化,超过湿度阈值则发出报警信号,进而可以采用科学的方法控制探头观测环境的湿度,提高观测数据的稳定性、可靠性。本文介绍了该系统的设计思路和主要功能。  相似文献