نتایج جستجو برای: sar

تعداد نتایج: 17700  

Journal: :Ecology 2013
Fangliang He Stephen Hubbell

Researchers commonly use species-area relationships (SAR) to estimate extinction rates caused by habitat loss by reversing the SAR, extrapolating backward from area to calculate expected species loss. We have previously shown that the backward SAR method considerably overestimates extinction rates due to a previously unrecognized sampling artifact. Jacob Bock Axelsen, Uri Roll, Lewi Stone, and ...

1998
Jose G. Gonzalez Mark J. T. Smith Ingo S. Hontsch Lina J. Karam Kamesh Namuduri Harold Szu

This paper treats the compression of Synthetic Aperture Radar (SAR) imagery. SAR images are di cult to compress, relative to natural images, because SAR contains an inherent high frequency speckle. Today's state-of-the-art coders are designed to work with natural images, which have a lower frequency content. Thus, their performance on SAR is under par. In this paper we give an overview performa...

Journal: :The Plant cell 1991
E. R. Ward S. J. Uknes S. C. Williams S. S. Dincher D. L. Wiederhold D. C. Alexander P. Ahl-Goy J. P. Metraux J. A. Ryals

In a variety of plant species, the development of necrotic lesions in response to pathogen infection leads to induction of generalized disease resistance in uninfected tissues. A well-studied example of this "immunity" reaction is systemic acquired resistance (SAR) in tobacco. SAR is characterized by the development of a disease-resistant state in plants that have reacted hypersensitively to pr...

2012
Matej Kseneman Dušan Gleich

Synthetic Aperture Radar (SAR) technology is mainly used to obtain high-resolution images of ground areas in resolutions even less than meter. SAR is even capable of imaging a wide area of terrain and from two and more images it is possible to reconstruct a 3D digital elevation model of ground terrain. Good thing about SAR is an all whether operation and possibility to capture images under vari...

2011
Beibei Jing Shaohua Xu Mo Xu Yan Li Shuxin Li Jinmei Ding Yuelin Zhang

Systemic acquired resistance (SAR) is a defense mechanism induced in the distal parts of plants after primary infection. It confers long-lasting protection against a broad spectrum of microbial pathogens. Lack of high-throughput assays has hampered the forward genetic analysis of SAR. Here, we report the development of an easy and efficient assay for SAR and its application in a forward genetic...

2008
Juntuan Zhang Shiqi Huang Guangliang Zhu Jun Lin

Synthetic aperture radar (SAR) imaging has the characteristics of acquiring remote sensing data under all weather and all time. So SAR image change detection techniques have large advantage in abruptly natural and man-made disaster. Inherent speckle noise of SAR image badly obstructs the applications for SAR image change detection. SAR image belongs to non-Gaussian distribution in general, whic...

2017
Yu Zheng Wu Chen

Passive Global Navigation Satellite System (GNSS)-based Synthetic Aperture Radar (SAR), known as GNSS-SAR, is a new passive radar imaging system. However, compared with conventional SAR, range resolution of GNSS-SAR is significantly lower. To improve range resolution of GNSS-SAR is an interested topic for investigation. In this paper, a novel range compression algorithm for enhancing range reso...

2003
Bir Bhanu Yingqiang Lin

Recognition of occluded objects in synthetic aperture radar SAR images is a signi cant problem for automatic target recognition Stochastic models provide some attractive features for pattern matching and recognition under partial occlusion and noise In this paper we present a discrete hidden Markov modeling HMM based approach for recognizing objects in synthetic aperture radar SAR images We ide...

2010
S.-J. Wei X.-L. Zhang J. Shi G. Xiang

Abstract—Synthetic Aperture Radar (SAR) can obtain a twodimensional image of the observed scene. However, the resolution of conventional SAR imaging algorithm based on Matched Filter (MF) theory is limited by the transmitted signal bandwidth and the antenna length. Compressed sensing (CS) is a new approach of sparse signals recovered beyond the Nyquist sampling constraints. In this paper, a hig...

Journal: :Plant physiology 2011
Beibei Jing Shaohua Xu Mo Xu Yan Li Shuxin Li Jinmei Ding Yuelin Zhang

Systemic acquired resistance (SAR) is a defense mechanism induced in the distal parts of plants after primary infection. It confers long-lasting protection against a broad spectrum of microbial pathogens. Lack of high-throughput assays has hampered the forward genetic analysis of SAR. Here, we report the development of an easy and efficient assay for SAR and its application in a forward genetic...

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