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991.
江汉平原印支期以来的盆山耦合关系及下古生界油气响应 总被引:5,自引:1,他引:4
利用构造地质学和油气系统理论,以盆地构造-沉积分析技术为手段,研究了印支期以来江汉平原与周缘造山带的耦合关系,探讨了江汉平原的构造演化及其对油气成藏的控制作用。印支期以来江汉平原及周缘经历了挤压、拉张、挤压3次大的构造应力场的转换,使古生代海相碳酸盐岩沉积为主的盆地具有改造盆地的特点;一方面强烈的抬升、剥蚀使早期聚集的油气经历改造和再分配、再聚集过程,另一方面燕山期构造活动使逆冲推覆构造成为该区重要勘探领域。综合分析表明,位于台、盆转换带的宜昌-珂理-簰州区带是目前江汉平原及周缘下古生界油气勘探的有利地区。 相似文献
992.
In this letter, we conduct analysis on the optimum design for RF-to-optical up-converter in coherent optical OFDM systems using an optical I/Q modulator. We first derive closed-form expressions for the nonlinearity in the optical I/Q modulator, represented by two-tone intermodulation products as a function of the bias point and modulation index. Additionally, we perform a numerical simulation to identify Q-penalty and the excess modulation insertion loss under various transmitter conditions. We find that in contrast to the direct-detected system, the optimal modulator bias point for the coherent system is pi, where the Q-penalty and excess loss are minimized 相似文献
993.
Yiping Wang Na Chen Binfeng Yun Yiping Cui 《Photonics Technology Letters, IEEE》2007,19(16):1242-1244
A measurement method has been developed to determine the full-field deformation of a simply supported plane plate under transverse load. The method utilizes strain information provided by a set of four fiber Bragg grating sensors mounted on the plate in a way that all sensors measure strains along one certain direction. The sensors were interrogated using a wavelength swept fiber laser. Utilizing the strain information and the first four terms of Navier solution of simply supported rectangular plate, the necessary parameters for determining the deflection could be computed. By substituting the values of x- and -y- coordinates of each position on the rectangle plate, the full-field deformation information can be obtained. Single-point loading tests were experimentally performed to verify the accuracy of the method. 相似文献
994.
浅谈火灾调查的边缘化趋势 总被引:1,自引:0,他引:1
从火灾调查实际工作状态出发,提出火灾调查存在地位边缘化的趋势,并在分析边缘化趋势原因的基础上提出了相应的对策,供火灾调查同仁探讨。 相似文献
995.
A Subcarriers Allocation Scheme for Cognitive Radio Systems Based on Multi-Carrier Modulation 总被引:1,自引:0,他引:1
Tao Luo Tao Jiang Weidong Xiang Hsiao-Hwa Chen 《Wireless Communications, IEEE Transactions on》2008,7(9):3335-3340
Cognitive radio (CR) is a dynamic spectrum access technology as a solution to spectrum under-utilization problem in some licensed bands. Operating over an exceedingly wide spectrum, CR systems usually adopt multi-carrier modulation (MCM) to implement flexible channelization. Consequently, efficient channel allocation scheme becomes extremely important to an MCM based CR (MCM-CR) system. In this paper, a maximum likelihood detection model is developed to detect the presence and locations of licensed users (LUs) signals in the frequency domain. Performance of the detection model, including the optimal detection region, detection probability and false alarm probability, is analyzed. A one-order two-state Markovian chain model is proposed to predict channel status information. In particular, a novel subcarrier allocation scheme for MCM-CR systems is proposed, taking into account the confidence of channel estimation, quality of services (QoS) of rental users (RUs) and throughput. To validate the analytical results, simulations have been conducted to show effectiveness of the proposed scheme. 相似文献
996.
重构在框架开发中的研究与应用 总被引:2,自引:0,他引:2
框架和应用能够通过重构相互促进,应用和框架的并行开发可以加速框架的开发过程.从框架与应用的中间层,框架与应用的接口的结构和形式等方面,对此过程中的重构方法进行了讨论,提出了几种适应于框架与应用并行开发的重构手段. 相似文献
997.
998.
Interpretation of scatterometer ocean surface wind vector EOFs over the Northwestern Pacific 总被引:1,自引:0,他引:1
Jiayi Pan Xiao-Hai Yan Quanan ZhengW.Timothy Liu Victor V Klemas 《Remote sensing of environment》2003,84(1):53-68
Satellite scatterometer winds over the northwestern Pacific were analyzed with the vector empirical orthogonal function (VEOF) method. The Hilbert-Huang transform (HHT), a newly developed non-linear and non-stationary time series data processing method, was also employed in the analysis. A combination of European Remote Sensing Satellite (ERS) −1/2 scatterometer, NASA Scatterometer (NSCAT) and NASA's Quick Scatterometer (QuikSCAT) winds covering the period from January 1992 to April 2000 and the area of 0-50°N, 100-148°E constitutes the baseline for this study. The results indicate that annual cycles dominate the two leading VEOF modes. The first VEOF shows the East Asian monsoon features and the second represents a spring-autumn oscillation. We removed the annual signal from the data set and calculated the interannual VEOFs. The first interannual VEOF represents the interannual variability existing in the spring-autumn oscillation. The temporal mode is correlated with the Southern Oscillation Index (SOI), but has a half-year lag with respect to the SOI. The spatial mode of the first interannual VEOF reflects the response of the tropical and extratropical winds to ENSO events. The second interannual VEOF is another ENSO related mode, and the temporal VEOF mode is correlated with the SOI with a correlation coefficient of 0.78, revealing the wind variability over mid-latitudes, which is associated with ENSO events. Further analysis indicated that the wind variability over the coast of East Asia represents anomalies of a Hadley cell. The quasi-biennial oscillation (QBO) was found in the temporal mode, indicating and verifying that the QBO in the wind fields is related to ENSO events. The third VEOF shows the interannaul variability in the winter-summer mode and displays the interannual variability of the East Asian monsoon. The three leading interannual VEOFs are statistically meaningful as confirmed by a significance test. 相似文献
999.
Gregory S. Ho Chen Huang Emily A. Carter 《Current Opinion in Solid State & Materials Science》2007,11(5-6):57-61
Orbital-free density functional theory (OF-DFT) can be made to scale linearly with sample size, allowing thousands of atoms to be treated explicitly with quantum mechanics. State-of-the-art kinetic energy density functionals and ion–electron pseudopotentials are used to obtain accurate structural property predictions for nanoparticles, nanowires, extended surfaces, and nanoindentation of simple metals. 相似文献
1000.
大型空分设备的工艺流程不同,采取的氪、氙预浓缩技术也不同。介绍了适用于不同流程的从液氧中提取氪-氙浓缩物和从富氧液空中提取氪-氙浓缩物的氪、氙预浓缩工艺原理、技术参数和特点。 相似文献