Mapping arctic landfast ice extent using L-band synthetic aperture radar interferometry

In recent years methods have been developed to extract the seaward landfast ice edge from series of remote sensing images, with most of them relying on incoherent change detection in optical, infrared, or radar amplitude imagery. While such approaches provide valuable results, some still lack the required level of robustness and all lack the ability to fully automate the detection and mapping of landfast ice over large areas and long time spans. This paper introduces an alternative approach to mapping landfast ice extent that is based on coherent processing of interferometric L-band Synthetic Aperture Radar (SAR) data. The approach is based on a combined interpretation of interferometric phase pattern and interferometric coherence images to extract the extent and stability of landfast ice. Due to the low complexity of the base imagery used for landfast ice extraction, significant improvements in automation and reduction of required manual interactions by operators can be achieved. A performance analysis shows that L-band interferometric SAR (InSAR) data enable the mapping of landfast ice with high robustness and accuracy for a wide range of environmental conditions.     

一种高效SMP Cache一致性协议及其实现技术的研究

结点控制器是并行多处理机计算机系统设计中除CPU外的最复杂部件,随着设计工艺水平的提高,它的功能也日益增多。文章将深入介绍SMP多处理机系统结点控制器设计中的一种高效Cache一致性协议以及实现方面的关键技术。     

Joint multiple parameters estimation for coherent chirp signals using vector sensor array

In this paper, an algorithm is proposed to estimate starting frequency （SF）, chirp rate （CR）, 2-D direction-of-arrivals （DOA） and polarization of coherent chirp signals with vector sensor arrays. The fractional Fourier transformation （FRFT） is used to estimate SF and CR of chirp signals in this method. And a new correlation matrix is reconstructed to suppress the noise. The property of the vector sensor array is employed to solve the problem of insufficient rank from signal coherence. The L-shaped uniform array of expend aperture is used to improve the precision of es- timation, and the method of solving the ambiguity of angle under the condition of coherent signals is presented. The performance of this algorithm is compared with that of spatial smoothing method to verify the efficacy of this approach.     

Exploiting Network Locality for CC-NUMA Multiprocessors

The Journal of Supercomputing - Rapid advances in interconnection networks in multiprocessors are closing the gap between computation and communication. Given this trend, how can we utilize fast...     

二进小波与扩散滤波结合的光学相干层析图像降噪

斑点抑制各向异性扩散(SRAD)是一种重要的图像降噪方法。将二进小波与SRAD结合,提出一种光学相干层析图像的二进小波扩散滤波降噪方法。该方法利用二进小波分解得到的不同尺度间小波系数的相关性区分边缘和噪声,修改SRAD中扩散系数得到新的扩散系数计算公式。实验表明,新方法具有更好的降噪能力,降噪后得到的图像的信噪比和对比度噪声比率等量化衡量指标都优于经典SRAD方法。     

支持线程级猜测的存储体系结构设计

在线程级猜测中进行数据依赖相关检测时,存在Cache一致性协议无法容忍线程切换引起的Cache块替换等问题。为此,通过分析推测线程数据管理模型,结合推测线程切概率低的特点,提出一种分布-共享式恢复缓冲区结构。该结构在进行Cache一致性检验时结合作废向量和版本优先级寄存器进行数据依赖检测,利用L2 Cache进行推测数据缓冲和恢复以支持推测线程切换。修改SESC模拟器以验证和评估该存储体系结构。实验结果表明,在保持模拟器理想加速比的情况下,该存储体系结构可以较好地支持推测线程切换。     

时空相关性在多物体碰撞检测中的应用

尽管利用虚拟环境中物体运动的时空相关性来加速物体间的碰撞检测，可以取得不错的效果，但目前的时空相关性算法只应用在两个物体的碰撞检测中，而不能处理多个物体同时发生碰撞的情况；另外，利用时空相关性尚无法解决快速运动物体的碰撞检测问题。针对传统算法的这两个缺陷，在综合利用空间区域划分和时空相关性算法的基础上，通过修改虚拟对象的内部数据结构提出了一种改进算法，实验结果表明，该算法不仅可实现多个物体同时发生碰撞的检测，而且能保证算法在物体高速运动时的有效性。     

Large-scale mapping of boreal forest in SIBERIA using ERS tandem coherence and JERS backscatter data

Siberia's boreal forests represent an economically and ecologically precious resource, a significant part of which is not monitored on a regular basis. Synthetic aperture radars (SARs), with their sensitivity to forest biomass, offer mapping capabilities that could provide valuable up-to-date information, for example about fire damage or logging activity. The European Commission SIBERIA project had the aim of mapping an area of approximately 1 million km² in Siberia using SAR data from two satellite sources: the tandem mission of the European Remote Sensing Satellites ERS-1/2 and the Japanese Earth Resource Satellite JERS-1. Mosaics of ERS tandem interferometric coherence and JERS backscattering coefficient show the wealth of information contained in these data but they also show large differences in radar response between neighbouring images. To create one homogeneous forest map, adaptive methods which are able to account for brightness changes due to environmental effects were required. In this paper an adaptive empirical model to determine growing stock volume classes using the ERS tandem coherence and the JERS backscatter data is described. For growing stock volume classes up to 80 m³/ha, accuracies of over 80% are achieved for over a hundred ERS frames at a spatial resolution of 50 m.     

Self-Deception and Emotional Coherence

This paper proposes that self-deception results from the emotional coherence of beliefs with subjective goals. We apply the HOTCO computational model of emotional coherence to simulate a rich case of self-deception from Hawthorne's The Scarlet Letter.We argue that this model is more psychologically realistic than other available accounts of self-deception, and discuss related issues such as wishful thinking, intention, and the division of the self.     

鲁棒的镜头边缘检测融合算法

对于镜头骤变检测，通过最小扩展树算法(MST)提取保留了视频帧空间信息的颜色聚合向量直方图、引入了动态自适应阈值和时间阻尼，使得骤变检测效率高；对于渐变检测，通过分析其数学产生模型，根据模型特性实现渐变镜头检测；最后，采用一个良好的融合策略同时完成骤变和渐变。