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61.
FA WenZhe & JIN YaQiu Key Laboratory of Wave Scattering Remote Sensing Information Fudan University Shanghai China 《中国科学:信息科学(英文版)》2010,(1):168-181
In China’s first lunar exploration project, Chang-E 1 (CE-1), a multi-channel microwave radiometer was aboard the satellite, with the purpose of measuring microwave brightness temperature from lunar surface and surveying the global distribution of lunar regolith layer thickness. In this paper, the primary 621 tracks of swath data measured by Chang-E 1 microwave radiometer from November 2007 to February 2008 are collected and analyzed. Using nearest neighbor interpolation based on the sun incidence angle in ... 相似文献
62.
实时操作系统对多任务资源访问控制提出了较高的要求.资源竞争常会引起优先级翻转问题导致任务阻塞,增加资源等待延迟时间.传统资源访问控制协议可以部分解决此问题,但是存在上下文切换次数高,任务调度效率低等不足.在结合SRP协议的提前阻塞特性和MiniCore实时调度器设计后,分析了协议中任务调度规则,指出了调度器支持SRP协议时效率低下的原因,并引入胜者树结构改进就绪队列,给出了新的任务搜索算法.理论分析与实验结果表明改进的调度器在任务集规模较大时,提高了调度效率,较好的支持了SRP协议. 相似文献
63.
Neural networks trained over radiative transfer simulations constitute the basis of several operational algorithms to estimate canopy biophysical variables from satellite reflectance measurements. However, only little attention was paid to the training process which has a major impact on retrieval performances. This study focused on the several modalities of the training process within neural network estimation of LAI, FCOVER and FAPAR biophysical variables. Performances were evaluated over both actual experimental observations and model simulations. The SAIL and PROSPECT radiative transfer models were used here to simulate the training and the synthetic test datasets. Measurements of LAI, FCOVER and FAPAR were achieved over the Barrax (Spain) agricultural site for a range of crop types concurrently to CHRIS/PROBA satellite image acquisition. Results showed that the spectral band selection was specific to LAI, FCOVER and FAPAR variables. The optimal band set provided significantly improved performances for LAI, while only small differences were observed for the other variables. Gaussian distributions of the radiative transfer model input variables performed better than uniform distributions for which no prior information was exploited. Including moderate uncertainties in the reflectance simulations used in the training process improved the flexibility of the neural network in cases where simulations departed slightly from observations. Simple neural network architecture with a single hidden layer of five tangent sigmoid transfer functions was performing as good as more complex architectures if the training dataset was larger than ten times the number of coefficients to tune. Small sensitivity of performances was observed depending on the way the solution was selected when several networks were trained in parallel. Finally, comparison with a NDVI based approach showed the generally better retrieval accuracy of neural networks. 相似文献
64.
A new approach is introduced for turbidite modeling, leveraging the potential of computational fluid dynamics methods to simulate the flow processes that led to turbidite formation. The practical use of numerical flow simulation for the purpose of turbidite modeling so far is hindered by the need to specify parameters and initial flow conditions that are a priori unknown. The present study proposes a method to determine optimal simulation parameters via an automated optimization process. An iterative procedure matches deposit predictions from successive flow simulations against available localized reference data, as in practice may be obtained from well logs, and aims at convergence towards the best-fit scenario. The final result is a prediction of the entire deposit thickness and local grain size distribution. The optimization strategy is based on a derivative-free, surrogate-based technique. Direct numerical simulations are performed to compute the flow dynamics. A proof of concept is successfully conducted for the simple test case of a two-dimensional lock-exchange turbidity current. The optimization approach is demonstrated to accurately retrieve the initial conditions used in a reference calculation. 相似文献
65.
In this work, we address the problem of transforming seismic reflection data into an intrinsic rock property model. Specifically, we present an application of a methodology that allows interpreters to obtain effective porosity 3D maps from post-stack 3D seismic amplitude data, using measured density and sonic well log data as constraints. In this methodology, a 3D acoustic impedance model is calculated from seismic reflection amplitudes by applying an L1-norm sparse-spike inversion algorithm in the time domain, followed by a recursive inversion performed in the frequency domain. A 3D low-frequency impedance model is estimated by kriging interpolation of impedance values calculated from well log data. This low-frequency model is added to the inversion result which otherwise provides only a relative numerical scale. To convert acoustic impedance into a single reservoir property, a feed-forward Neural Network (NN) is trained, validated and tested using gamma-ray and acoustic impedance values observed at the well log positions as input and effective porosity values as target. The trained NN is then applied for the whole reservoir volume in order to obtain a 3D effective porosity model. While the particular conclusions drawn from the results obtained in this work cannot be generalized, such results suggest that this workflow can be applied successfully as an aid in reservoir characterization, especially when there is a strong non-linear relationship between effective porosity and acoustic impedance. 相似文献
66.
用一种遗传算法的调度策略,以大维度矩阵求逆为实验对象,探索在多核中如何完成任务的均衡分配问题,以达到加速效果.算法利用系统资源的弹性,自动搜寻可以并行的子任务并将其合理地分配到相应计算节点中,提高了多核系统资源调度性能,实现了对用户提交的任务的优化调度,达到了均衡系统各处理器计算负载和提高多核系统的总体性能的目标. 相似文献
67.
68.
LU Tao 《数字社区&智能家居》2008,(35)
通过对Template框架的研究,对在该框架中引入SVG Tiny技术进行了研究,并为该框架设计和实现了SVG Tiny创作工具。 相似文献
69.
湿法相分离不对称超滤膜形成机理 总被引:1,自引:0,他引:1
本文选择了憎水的极怀非普质子性聚砜和亲水的极性质子怀聚砜酰胺两种膜材料,从铸膜液组成和凝胶过程两方面,用气相色谱和高效液相色谱研究了表征膜材料-溶剂-添加剂-水作用力的混合自由焓,平衡分配常数,及其与膜性能,不同溶剂特性粘度,雾点值和溶解度参数的关系,提出了铸膜液中有机溶剂的作用机理,及不对称超滤膜形成的一些规律。 相似文献
70.
YA地区Y14块位于YA构造南部,该区钻探的Y14井与Y14—1井通过分析砂体不连通,但在叠后反演波阻抗剖面上不能有效分辨。通过岩石物理分析及其叠前反演,揭示了砂体的横向展布规律并验证了两口井的钻探情况。 相似文献