35,208 results
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2. Latent Diffusion Model-Based T2T-ViT for SAR Ship Classification
- Author
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Qi, Yuhang, Wang, Lu, Li, Kaiyu, Liu, Haodong, Zhao, Chunhui, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Prates, Raquel Oliveira, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Sun, Yuqing, editor, Lu, Tun, editor, Wang, Tong, editor, Fan, Hongfei, editor, Liu, Dongning, editor, and Du, Bowen, editor
- Published
- 2024
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3. Experimental Analysis of Skip Connections for SAR Image Denoising
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Passah, Alicia, Kandar, Debdatta, Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Das, Swagatam, editor, Saha, Snehanshu, editor, Coello Coello, Carlos A., editor, and Bansal, Jagdish Chand, editor
- Published
- 2023
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4. A Novel Technique for Forest Height Estimation from SAR Radar Images Using the Omega K Algorithm
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Jancco-Chara, Jhohan, Palomino-Quispe, Facundo, Coaquira-Castillo, Roger, Clemente-Arenas, Mark, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Prates, Raquel Oliveira, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Narváez, Fabián R., editor, Proaño, Julio, editor, Morillo, Paulina, editor, Vallejo, Diego, editor, González Montoya, Daniel, editor, and Díaz, Gloria M., editor
- Published
- 2022
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5. Oil Spill Discrimination of SAR Satellite Images Using Deep Learning Based Semantic Segmentation
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Sudha, V., Vijendran, Anna Saro, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Prates, Raquel Oliveira, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Chaubey, Nirbhay, editor, Parikh, Satyen, editor, and Amin, Kiran, editor
- Published
- 2021
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6. Satellite-Based Water Depth Estimation: A Review
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Wen, Kaixiang, Li, Yong, Wang, Hua, Jing, Wenlong, Yang, Ji, Zhang, Chen, Wang, Zhou, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Kotenko, Igor, Editorial Board Member, Prates, Raquel Oliveira, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Xie, Yichun, editor, Li, Yong, editor, Yang, Ji, editor, Xu, Jianhui, editor, and Deng, Yingbin, editor
- Published
- 2020
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7. Application of Sentinel-1A Data in Offshore Wind Field Retrieval Within Guangdong Province
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Wu, Pinghao, Zhong, Kaiwen, Hu, Hongda, Zhao, Yi, Xu, Jianhui, Wang, Yunpeng, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Kotenko, Igor, Editorial Board Member, Prates, Raquel Oliveira, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Xie, Yichun, editor, Li, Yong, editor, Yang, Ji, editor, Xu, Jianhui, editor, and Deng, Yingbin, editor
- Published
- 2020
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8. Guest Editorial: Selected papers from RADAR 2022—International Conference on Radar Systems (Edinburgh, UK).
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Clemente, Carmine and Balleri, Alessio
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BISTATIC radar ,RADAR ,CONTINUOUS wave radar ,RADAR cross sections ,RADAR signal processing ,SYNTHETIC aperture radar - Abstract
This article is a guest editorial for the IET Radar, Sonar & Navigation journal, focusing on selected papers from the RADAR 2022 conference held in Edinburgh, UK. The conference provided an opportunity for radar specialists from 22 countries to explore the latest developments in radar systems. Key topics discussed at the conference included new radar trends, target detection (with a focus on drones), low-frequency radar, and cognitive radar. The special issue contains 17 papers based on extended work presented at the conference, covering topics such as multistatic radar, passive radar, target signatures, and advanced radar processing techniques. The authors hope that this special issue will serve as a valuable resource for further research in the field. [Extracted from the article]
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- 2024
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9. An Efficient Feature Selection for SAR Target Classification
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Amrani, Moussa, Yang, Kai, Zhao, Dongyang, Fan, Xiaopeng, Jiang, Feng, Hutchison, David, Series Editor, Kanade, Takeo, Series Editor, Kittler, Josef, Series Editor, Kleinberg, Jon M., Series Editor, Mattern, Friedemann, Series Editor, Mitchell, John C., Series Editor, Naor, Moni, Series Editor, Pandu Rangan, C., Series Editor, Steffen, Bernhard, Series Editor, Terzopoulos, Demetri, Series Editor, Tygar, Doug, Series Editor, Weikum, Gerhard, Series Editor, Zeng, Bing, editor, Huang, Qingming, editor, El Saddik, Abdulmotaleb, editor, Li, Hongliang, editor, Jiang, Shuqiang, editor, and Fan, Xiaopeng, editor
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- 2018
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10. Smartphone-assisted portable paper-based biosensors for rapid and sensitive detection of biomarkers in urine.
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Jin, Chengcheng, Yang, Shuang, Zheng, Junlei, Chai, Fang, and Tian, Miaomiao
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SMARTPHONES , *GLUCOSE oxidase , *HORSERADISH peroxidase , *BIOSENSORS , *BIOMARKERS , *ELECTROCHEMICAL sensors , *URINE , *SYNTHETIC aperture radar - Abstract
Schematic diagram depicting the synthesis process of the intelligent paper-based biosensor and its colorimetric detection application for biomarkers in urine. (FP: filter paper; CPBA: Carboxyphenylboric acid; HRP: horseradish peroxidase; TMB: 3,3′,5,5′-tetramethylbenzidine; GLU: glusose; UA: uric acid; SAR: sarcosine; GOx: glucose oxidase; UOx: urate oxidase; SOx: urate oxidase.) [Display omitted] • A green, low-cost, portable and visual intelligent paper-based biosensor was created. • This sensor immobilized HRP in horseradish by a borate-modified filter paper. • This sensor can detect many substances simultaneously and improve detection efficiency. • This sensor boasts the advantages of superior sensitivity, stability and selectivity. In the increasing demand for real-time testing, the imperative for a straightforward, rapid, portable, and effective biosensor is evident. In this study, an intelligent paper-based biosensor was developed, employing cost-effective and readily available filter paper as a matrix to prepare boronate affinity paper-based materials. The immobilization of horseradish peroxidase (HRP) from crude horseradish extract onto the material surface was realized. Ultimately, a cold assembly technique was employed to construct this intelligent paper-based biosensor, which combined with a smartphone APP, facilitated the easy, accurate, and simultaneous detection of the content of glucose (GLU), uric acid (UA), and sarcosine (SAR) in urine, significantly enhancing the convenience and practicality of real-time monitoring. Additionally, UV spectroscopy served as an auxiliary method to affirm the reliability of the detection outcomes. For the detection of GLU, UA, and SAR, the biosensor exhibited linear ranges of 2–200, 2–500, and 2–500 µmol L–1, respectively, with detection limits (LODs) of 1 µmol L–1 for all analytes. In practical urine sample analysis, the recovery rates of GLU, UA, and SAR detected by the intelligent paper-based biosensors were within a reasonable range, with relative standard deviations below 3.5 %. This fully demonstrates the high accuracy and reliability of the intelligent paper-based biosensor. The development of this low-cost, portable biosensor provides a new method for the detection of biomarkers related to H 2 O 2. [ABSTRACT FROM AUTHOR]
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- 2024
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11. Polarimetric Synthetic Aperture Radar Speckle Filter Based on Joint Similarity Measurement Criterion.
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Tang, Fanyi, Li, Zhenfang, Zhang, Qingjun, Suo, Zhiyong, Zhang, Zexi, Xing, Chao, and Guo, Huancheng
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SYNTHETIC aperture radar ,POLARIMETRY ,SYNTHETIC apertures ,SPECKLE interference ,ADAPTIVE filters ,FILTER paper - Abstract
Polarimetric Synthetic Aperture Radar (PolSAR) data is inherently characterized by speckle noise, which significantly deteriorates certain aspects of the quality of the PolSAR data processing, including the polarimetric decomposition and target interpretation. With the rapid increase in PolSAR resolution, SAR images in complex natural and artificial scenes exhibit non-homogeneous characteristics, which creates an urgent demand for high-resolution PolSAR filters. To address these issues, a new adaptive PolSAR filter based on joint similarity measure criterion (JSMC) is proposed in this paper. Firstly, a scale-adaptive filtering window is established in order to preserve the texture structure based on a multi-directional ratio edge detector. Secondly, the JSMC is proposed in order to accurately select homogeneous pixels; it describes pixel similarity based on both space distance and polarimetric distance. Thirdly, the homogeneous pixels are filtered based on statistical averaging. Finally, the airborne and spaceborne real data experiment results validate the effectiveness of our proposed method. Compared with other filters, the filter proposed in this paper provides a better outcome for PolSAR data in speckle suppression, edge texture, and the preservation of polarimetric properties. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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12. Recovering Piecewise Smooth Functions from Nonuniform Fourier Measurements
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Adcock, Ben, Gataric, Milana, Hansen, Anders C., Barth, Timothy J., Series editor, Griebel, Michael, Series editor, Keyes, David E., Series editor, Nieminen, Risto M., Series editor, Roose, Dirk, Series editor, Schlick, Tamar, Series editor, Kirby, Robert M., editor, Berzins, Martin, editor, and Hesthaven, Jan S., editor
- Published
- 2015
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13. Big, Linked and Open Data: Applications in the German Aerospace Center
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Nikolaou, C., Kyzirakos, K., Bereta, K., Dogani, K., Giannakopoulou, S., Smeros, P., Garbis, G., Koubarakis, M., Molina, D. E., Dumitru, O. C., Schwarz, G., Datcu, M., Presutti, Valentina, editor, Blomqvist, Eva, editor, Troncy, Raphael, editor, Sack, Harald, editor, Papadakis, Ioannis, editor, and Tordai, Anna, editor
- Published
- 2014
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14. Noise Resistant Gradient Calculation and Edge Detection Using Local Binary Patterns
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Teutsch, Michael, Beyerer, Jürgen, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Park, Jong-Il, editor, and Kim, Junmo, editor
- Published
- 2013
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15. Towards the Development of a Thyroid Ultrasound Biometric Scheme Based on Tissue Echo-morphological Features
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Seabra, Josè C. R., Fred, Ana L. N., Fred, Ana, editor, Filipe, Joaquim, editor, and Gamboa, Hugo, editor
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- 2010
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16. Phase History Model for Spaceborne SAR with Large Observation Time
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Guo, Deming, Xu, Huaping, Li, Jingwen, and Lee, Gary, editor
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- 2012
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17. Effect of Different Target Decomposition Techniques on Classification Accuracy for Polarimetric SAR Data
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Turkar, Varsha, Rao, Y. S., Shah, Ketan, editor, Lakshmi Gorty, V. R., editor, and Phirke, Ajay, editor
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- 2011
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18. Anisotropic Regularization of Posterior Probability Maps Using Vector Space Projections. Application to MRI Segmentation
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Rodriguez-Florido, M. A., Cárdenes, R., Westin, C. -F., Alberola, C., Ruiz-Alzola, J., Goos, Gerhard, editor, Hartmanis, Juris, editor, van Leeuwen, Jan, editor, Moreno-Díaz, Roberto, editor, and Pichler, Franz, editor
- Published
- 2003
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19. Scale Space Exploration for Mining Image Information Content
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Ciucu, Mariana, Heas, Patrick, Datcu, Mihai, Tilton, James C., Goos, Gerhard, editor, Hartmanis, Juris, editor, van Leeuwen, Jan, editor, Carbonell, Jaime G., editor, Siekmann, Jörg, editor, Zaïane, Osmar R., editor, Simoff, Simeon J., editor, and Djeraba, Chabane, editor
- Published
- 2003
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20. Speckle Suppressing Based on Fuzzy Generalized Morphological Filter
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Jiang, Lihui, Guo, Yanying, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Carbonell, Jaime G., editor, Siekmann, Jörg, editor, Yeung, Daniel S., editor, Liu, Zhi-Qiang, editor, Wang, Xi-Zhao, editor, and Yan, Hong, editor
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- 2006
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21. An Innovative Concept for Image Information Mining
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Datcu, Mihai, Seidel, Klaus, Goos, Gerhard, editor, Hartmanis, Juris, editor, van Leeuwen, Jan, editor, Carbonell, Jaime G., editor, Siekmann, Jörg, editor, Zaïane, Osmar R., editor, Simoff, Simeon J., editor, and Djeraba, Chabane, editor
- Published
- 2003
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22. Statistical Information Theory and Geometry for SAR Image Analysis : Invited Paper
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Alejandro C. Frery
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Synthetic aperture radar ,Geodesic ,Computer science ,business.industry ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Image processing ,Disjoint sets ,Information theory ,Image (mathematics) ,Computer vision ,Information geometry ,Artificial intelligence ,Road map ,business - Abstract
This paper is intended as a road map for the literature on Synthetic Aperture Radar (SAR) image processing and analysis with Information-Theoretic and Information-Geometric Statistical tools. We do this by commenting upon seemingly disjoint problems, and showing that they can be tackled successfully within the same framework: tools that arise from using Information Theory (entropies and divergences) and Information Geometry (geodesic distances) enhanced with Statistics.
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- 2019
23. ULTRA-WIDE BAND RADAR AND ITS APPLICATIONS.
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KHOWALA, ABHISHEK
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SYNTHETIC aperture radar ,FREQUENCY-domain analysis ,ANTENNAS (Electronics) ,MONOPOLE antennas ,SIGNAL processing ,RADAR ,ULTRA-wideband radar - Abstract
This paper uses MATLAB software to demonstrate the performance of UWBSAR and conducts a comparative study with data obtained from conventional radar. It compares various antennas that support UWB, such as Vivaldi, MIMO, and monopole antennas, analyzed using SIMULINK. The paper discusses the design of UWBSAR to provide a comprehensive analytical picture of the processed images. The focus is on frequency domain analysis in general and the Range Migration Algorithm (RMA) in particular. The data obtained after signal processing is recorded to estimate the crossrange resolution, which is then compared with conventional SAR. The cross-range resolution estimated using UWBSAR is found to be lower than that of conventional radar, proving that UWBSAR is a better alternative for obtaining sharper images in short-range applications. High-quality images are reconstructed using a combination of UWB radar, SAR processing, and proposed algorithms to improve image quality. The investigation includes positive image generation to enhance sharpness and near-field imaging procedures. This paper also describes Ultra-Wideband (UWB) Synthetic Aperture Radar (SAR) and its application in operating at low frequencies to detect obscured targets beneath foliage. While it has obvious military applications, it also has civilian uses, such as in geophysical studies and weather forecasting. Several applications have been identified for both military and civilian environments. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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24. Disturbance rejection control of airborne radar stabilized platform based on active disturbance rejection control inverse estimation algorithm
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Mei, Dong and Yu, Zhu-Qing
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- 2021
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25. Forest fire progress monitoring using dual-polarisation Synthetic Aperture Radar (SAR) images combined with multi-scale segmentation and unsupervised classification.
- Author
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Shama, Age, Zhang, Rui, Wang, Ting, Liu, Anmengyun, Bao, Xin, Lv, Jichao, Zhang, Yuchun, and Liu, Guoxiang
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SYNTHETIC aperture radar ,FOREST fires ,WILDFIRE prevention ,FOREST fire prevention & control ,REMOTE sensing ,FOREST monitoring ,CLOUDINESS - Abstract
Background: The cloud-penetrating and fog-penetrating capability of Synthetic Aperture Radar (SAR) give it the potential for application in forest fire progress monitoring; however, the low extraction accuracy and significant salt-and-pepper noise in SAR remote sensing mapping of the burned area are problems. Aims: This paper provides a method for accurately extracting the burned area based on fully exploiting the changes in multiple different dimensional feature parameters of dual-polarised SAR images before and after a fire. Methods: This paper describes forest fire progress monitoring using dual-polarisation SAR images combined with multi-scale segmentation and unsupervised classification. We first constructed polarisation feature and texture feature datasets using multi-scene Sentinel-1 images. A multi-scale segmentation algorithm was then used to generate objects to suppress the salt-and-pepper noise, followed by an unsupervised classification method to extract the burned area. Key results: The accuracy of burned area extraction in this paper is 91.67%, an improvement of 33.70% compared to the pixel-based classification results. Conclusions: Compared with the pixel-based method, our method effectively suppresses the salt-and-pepper noise and improves the SAR burned area extraction accuracy. Implications: The fire monitoring method using SAR images provides a reference for extracting the burned area under continuous cloud or smoke cover. This paper describes a method to monitor forest fire progress using dual-polarisation Synthetic Aperture Radar (SAR) images combined with multi-scale segmentation and unsupervised classification. We aimed to take full advantage of the many different dimensions of feature parameter changes caused by forest fires, relying on time-series dual-polarised SAR imagery to achieve burned area extraction and forest fire progress monitoring. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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26. Carton-Missing Detection System Based on the Millimeter-Wave Imaging Technique.
- Author
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Hu, Guangxiao, Gao, Bingxi, Xia, Yu, Chen, Huiyong, and Lian, Wenxiu
- Abstract
Millimeter wave operates within a wavelength range of 1mm to 10mm and can penetrate through various non-metallic materials, such as the paperboard and plastic films commonly used in cigarette packaging boxes. In comparison to X-ray devices, millimeter wave imagers have the added advantage of not emitting ionizing radiation and having lower electromagnetic radiation output than the standard limit for mobile phone. Given these characteristics, we believe that utilizing millimeter wave imaging technology for detecting missing carton in packaged cigarette boxes could be a viable solution. The paper presents the fundamental imaging theory and showcases some images of cigarette boxes. The results demonstrate that our millimeter wave imager can produce clear images of packaged cigarette boxes with missing carton. We anticipate that this system has significant potential for application in machine vision for tobacco and other similar industries. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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27. Trend Research on Maritime Autonomous Surface Ships (MASSs) Based on Shipboard Electronics: Focusing on Text Mining and Network Analysis.
- Author
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Kim, Jinsick, Han, Sungwon, Lee, Hyeyoung, Koo, Byeongsoo, Nam, Moonju, Jang, Kukjin, Lee, Jooyeoun, and Chung, Myoungsug
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TEXT mining ,DEEP learning ,SYNTHETIC aperture radar ,REAL-time computing ,IMAGE recognition (Computer vision) ,ELECTRIC propulsion ,PROPULSION systems - Abstract
The growing adoption of electric propulsion systems in Maritime Autonomous Surface Ships (MASSs) necessitates advancements in shipboard electronics for safe, efficient, and reliable operation. These advancements are crucial for tasks such as real-time sensor data processing, control algorithms for autonomous navigation, and robust decision-making capabilities. This study investigates research trends in MASSs, using bibliographic analysis to identify policy and future research directions in this evolving field. We analyze 3363 MASS-related articles from the Web of Science database, employing co-occurrence word analysis and latent Dirichlet allocation (LDA) topic modeling. The findings reveal a rapidly growing field dominated by image recognition research. Keywords such as "datum", "image", and "detection" suggest a focus on collecting and analyzing marine data, particularly with deep learning for synthetic aperture radar imagery. LDA confirms this, with "image analysis and classification research" as the leading topic. The study also identifies national and organizational leaders in MASS research. However, research on Arctic routes lags behind that on other areas. This work provides valuable insights for policymakers and researchers, promoting a deeper understanding of MASSs and informing future policy and research agendas regarding the integration of electric propulsion systems within the maritime industry. [ABSTRACT FROM AUTHOR]
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- 2024
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28. Hardware accelerated range Doppler algorithm for SAR data processing using Zynq processor
- Author
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Mewada, Hiren K., Chaudhari, Jitendra, Patel, Amit V., Mahant, Keyur, and Vala, Alpesh
- Published
- 2021
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29. Leveraging Visual Language Model and Generative Diffusion Model for Zero-Shot SAR Target Recognition.
- Author
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Wang, Junyu, Sun, Hao, Tang, Tao, Sun, Yuli, He, Qishan, Lei, Lin, and Ji, Kefeng
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LANGUAGE models ,OPTICAL remote sensing ,COMPUTATIONAL electromagnetics ,KNOWLEDGE base ,SYNTHETIC aperture radar ,PRIOR learning ,IMAGE recognition (Computer vision) - Abstract
Simulated data play an important role in SAR target recognition, particularly under zero-shot learning (ZSL) conditions caused by the lack of training samples. The traditional SAR simulation method is based on manually constructing target 3D models for electromagnetic simulation, which is costly and limited by the target's prior knowledge base. Also, the unavoidable discrepancy between simulated SAR and measured SAR makes the traditional simulation method more limited for target recognition. This paper proposes an innovative SAR simulation method based on a visual language model and generative diffusion model by extracting target semantic information from optical remote sensing images and transforming it into a 3D model for SAR simulation to address the challenge of SAR target recognition under ZSL conditions. Additionally, to reduce the domain shift between the simulated domain and the measured domain, we propose a domain adaptation method based on dynamic weight domain loss and classification loss. The effectiveness of semantic information-based 3D models has been validated on the MSTAR dataset and the feasibility of the proposed framework has been validated on the self-built civilian vehicle dataset. The experimental results demonstrate that the first proposed SAR simulation method based on a visual language model and generative diffusion model can effectively improve target recognition performance under ZSL conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. Research on a Near-Field Millimeter Wave Imaging Algorithm and System Based on Multiple-Input Multiple-Output Sparse Sampling.
- Author
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Zhang, He, Zong, Hua, and Qiu, Jinghui
- Subjects
SYNTHETIC aperture radar ,MILLIMETER waves ,IMAGING systems ,WAVENUMBER ,BIVECTORS - Abstract
In order to reduce the hardware cost and data acquisition time in near-field scenarios, such as airport security imaging systems, this paper discusses the layout of a multiple-input multiple-output (MIMO) radar array. In view of the existing multi-input multiple-output imaging algorithm, the reconstructed image artifacts and aliasing problems caused by sparse sampling are discussed. In this paper, a multi-station radar array and a corresponding sparse MIMO imaging algorithm based on combined sparse sub-channels are proposed. By studying the wave–number spectrum of backscattered MIMO synthetic aperture radar (SAR) data, the nonlinear relationship between the wave number spectrum and reconstructed image is established. By selecting a complex gain vector, multiple channels are coherently combined effectively, thus eliminating aliasing and artifacts in the reconstructed image. At the same time, the algorithm can be used for the MIMO–SAR configuration of arbitrarily distributed transmitting and receiving arrays. A new multi-station millimeter wave imaging system is designed by using a frequency-modulated continuous wave (FMCW) chip and sliding rail platform as a planar SAR. The combination of the hardware system provides reconfiguration, convenience and economy for the combination of millimeter wave imaging systems in multiple scenes. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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31. Precise Motion Compensation of Multi-Rotor UAV-Borne SAR Based on Improved PTA.
- Author
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Cheng, Yao, Qiu, Xiaolan, and Meng, Dadi
- Subjects
IMAGE stabilization ,SYNTHETIC aperture radar ,GROUND motion ,NUMERICAL calculations ,ELECTRONIC data processing - Abstract
In recent years, with the miniaturization of high-precision position and orientation systems (POS), precise motion errors during SAR data collection can be calculated based on high-precision POS. However, compensating for these errors remains a significant challenge for multi-rotor UAV-borne SAR systems. Compared with large aircrafts, multi-rotor UAVs are lighter, slower, have more complex flight trajectories, and have larger squint angles, which result in significant differences in motion errors between building targets and ground targets. If the motion compensation is based on ground elevation, the motion error of the ground target will be fully compensated, but the building target will still have a large residual error; as a result, although the ground targets can be well-focused, the building targets may be severely defocused. Therefore, it is necessary to further compensate for the residual motion error of building targets based on the actual elevation on the SAR image. However, uncompensated errors will affect the time–frequency relationship; furthermore, the ω-k algorithm will further change these errors, resulting in errors in SAR images becoming even more complex and difficult to compensate for. To solve this problem, this paper proposes a novel improved precise topography and aperture-dependent (PTA) method that can precisely compensate for motion errors in the UAV-borne SAR system. After motion compensation and imaging processing based on ground elevation, a secondary focus is applied to defocused buildings. The improved PTA fully considers the coupling of the residual error with the time–frequency relationship and ω-k algorithm, and the precise errors in the two-dimensional frequency domain are determined through numerical calculations without any approximations. Simulation and actual data processing verify the effectiveness of the method, and the experimental results show that the proposed method in this paper is better than the traditional method. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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32. Complex-Valued Neural Networks – Recent Progress and Future Directions (Invited Paper)
- Author
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Akira Hirose
- Subjects
Synthetic aperture radar ,Artificial neural network ,Computer science ,Electronic engineering ,Complex valued - Abstract
This invited paper presents and discusses the recent progress, present and prospective applications, and the future directions of complex-valued neural networks (CVNNs) including hypercomplex-valued neural networks (HVNNs).
- Published
- 2014
33. Remote sensing in strategic applications (Review Paper)
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P.S. Roy and D.S. Srinivas
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Synthetic aperture radar ,Emerging technologies ,Computer science ,Mechanical Engineering ,General Chemical Engineering ,Multispectral image ,Biomedical Engineering ,General Physics and Astronomy ,Context (language use) ,Shuttle Radar Topography Mission ,Computer Science Applications ,Remote sensing (archaeology) ,Electrical and Electronic Engineering ,Digital elevation model ,Digital Earth ,Remote sensing - Abstract
Remote sensing has come a long way in the last three decades. The technology has reached all spheres of human activity and affected our life in innumerable ways. Some of the recent studies in this area have contributed towards better resolution, better precision and opened up a host of new application areas. The era of hyperspectral imaging is on, and it.is expected that it will soon overtake the multispectral imaging within a few years, Synthetic aperture radar interferometery has taken strides towards providing accurate digital elevation models than ever before, the recent shuttle radar topography mission has proven its capability, with a near coverage of the whole globe and the dictum of digital earth is soon going to be a reality. Information extraction from remote sensing .images has reached new heights with recent methodologies like the neural networks and contextual classification, enabling to create and incorporate external knowledge into the classification process. Some of these emerging technologies and processing methods in the context of strategic application areas have been discussed.
- Published
- 2001
34. Fuzzy-based MTD : A fuzzy decisive approach for moving target detection in multichannel SAR framework
- Author
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Jaya, Eppili and Krishna, B.T.
- Published
- 2020
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35. Radargrammetric 3D Imaging through Composite Registration Method Using Multi-Aspect Synthetic Aperture Radar Imagery.
- Author
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Luo, Yangao, Deng, Yunkai, Xiang, Wei, Zhang, Heng, Yang, Congrui, and Wang, Longxiang
- Subjects
SYNTHETIC aperture radar ,THREE-dimensional imaging ,SYNTHETIC apertures ,SPECKLE interference ,DIGITAL elevation models ,IMAGE registration ,RADIO telescopes - Abstract
Interferometric synthetic aperture radar (InSAR) and tomographic SAR measurement techniques are commonly used for the three-dimensional (3D) reconstruction of complex areas, while the effectiveness of these methods relies on the interferometric coherence among SAR images with minimal angular disparities. Radargrammetry exploits stereo image matching to determine the spatial coordinates of corresponding points in two SAR images and acquire their 3D properties. The performance of the image matching process directly impacts the quality of the resulting digital surface model (DSM). However, the presence of speckle noise, along with dissimilar geometric and radiometric distortions, poses considerable challenges in achieving accurate stereo SAR image matching. To address these aforementioned challenges, this paper proposes a radargrammetric method based on the composite registration of multi-aspect SAR images. The proposed method combines coarse registration using scale invariant feature transform (SIFT) with precise registration using normalized cross-correlation (NCC) to achieve accurate registration between multi-aspect SAR images with large disparities. Furthermore, the multi-aspect 3D point clouds are merged using the proposed radargrammetric 3D imaging method, resulting in the 3D imaging of target scenes based on multi-aspect SAR images. For validation purposes, this paper presents a comprehensive 3D reconstruction of the Five-hundred-meter Aperture Spherical radio Telescope (FAST) using Ka-band airborne SAR images. It does not necessitate prior knowledge of the target and is applicable to the detailed 3D imaging of large-scale areas with complex structures. In comparison to other SAR 3D imaging techniques, it reduces the requirements for orbit control and radar system parameters. To sum up, the proposed 3D imaging method with composite registration guarantees imaging efficiency, while enhancing the imaging accuracy of crucial areas with limited data. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. FS-5, paper 5: Earth observation instruments with e-scan antennas state-of-the-art and outlook
- Author
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F. Rostan, C. Buck, Salvatore D'Addio, M. Ludwig, Renato Croci, Ramon Torres, and C. Schaefer
- Subjects
Synthetic aperture radar ,Interferometry ,Earth observation ,Spaceborne radar ,Computer science ,Satellite antennas ,Marine technology ,Satellite navigation ,State (computer science) ,Remote sensing - Abstract
Spaceborne radars with electronically scanned antennas are in use on European satellites since the launch of Envisat in March 2002. Despite the higher complexity and consequently cost, electronically scanned antennas are more and more attractive for spaceborne radar. The return materialises either in significantly better system performance or in newly gained system feasibility.
- Published
- 2010
37. CCDS-YOLO: Multi-Category Synthetic Aperture Radar Image Object Detection Model Based on YOLOv5s.
- Author
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Huang, Min, Liu, Zexu, Liu, Tianen, and Wang, Jingyang
- Subjects
OBJECT recognition (Computer vision) ,SYNTHETIC apertures ,FEATURE extraction ,SYNTHETIC aperture radar ,IMAGE recognition (Computer vision) ,MARITIME management - Abstract
Synthetic Aperture Radar (SAR) is an active microwave sensor that has attracted widespread attention due to its ability to observe the ground around the clock. Research on multi-scale and multi-category target detection methods holds great significance in the fields of maritime resource management and wartime reconnaissance. However, complex scenes often influence SAR object detection, and the diversity of target scales also brings challenges to research. This paper proposes a multi-category SAR image object detection model, CCDS-YOLO, based on YOLOv5s, to address these issues. Embedding the Convolutional Block Attention Module (CBAM) in the feature extraction part of the backbone network enables the model's ability to extract and fuse spatial information and channel information. The 1 × 1 convolution in the feature pyramid network and the first layer convolution of the detection head are replaced with the expanded convolution, Coordinate Conventional (CoordConv), forming a CRD-FPN module. This module more accurately perceives the spatial details of the feature map, enhancing the model's ability to handle regression tasks compared to traditional convolution. In the detector segment, a decoupled head is utilized for feature extraction, offering optimal and effective feature information for the classification and regression branches separately. The traditional Non-Maximum Suppression (NMS) is substituted with the Soft Non-Maximum Suppression (Soft-NMS), successfully reducing the model's duplicate detection rate for compact objects. Based on the experimental findings, the approach presented in this paper demonstrates excellent results in multi-category target recognition for SAR images. Empirical comparisons are conducted on the filtered MSAR dataset. Compared with YOLOv5s, the performance of CCDS-YOLO has been significantly improved. The mAP@0.5 value increases by 3.3% to 92.3%, the precision increases by 3.4%, and the mAP@0.5:0.95 increases by 6.7%. Furthermore, in comparison with other mainstream detection models, CCDS-YOLO stands out in overall performance and anti-interference ability. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
38. A Visible and Synthetic Aperture Radar Image Fusion Algorithm Based on a Transformer and a Convolutional Neural Network.
- Author
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Hu, Liushun, Su, Shaojing, Zuo, Zhen, Wei, Junyu, Huang, Siyang, Zhao, Zongqing, Tong, Xiaozhong, and Yuan, Shudong
- Subjects
CONVOLUTIONAL neural networks ,SYNTHETIC aperture radar ,TRANSFORMER models ,IMAGE fusion ,SYNTHETIC apertures ,ALGORITHMS - Abstract
For visible and Synthetic Aperture Radar (SAR) image fusion, this paper proposes a visible and SAR image fusion algorithm based on a Transformer and a Convolutional Neural Network (CNN). Firstly, in this paper, the Restormer Block is used to extract cross-modal shallow features. Then, we introduce an improved Transformer–CNN Feature Extractor (TCFE) with a two-branch residual structure. This includes a Transformer branch that introduces the Lite Transformer (LT) and DropKey for extracting global features and a CNN branch that introduces the Convolutional Block Attention Module (CBAM) for extracting local features. Finally, the fused image is output based on global features extracted by the Transformer branch and local features extracted by the CNN branch. The experiments show that the algorithm proposed in this paper can effectively achieve the extraction and fusion of global and local features of visible and SAR images, so that high-quality visible and SAR fusion images can be obtained. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Image analysis and resolution for detection-based synthetic-aperture passive source localization.
- Author
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Cheney, Margaret, Scharf, Louis, Rhilinger, Matthew, Moore, Cole, and Celestin, Andre
- Subjects
IMAGE analysis ,ELECTROMAGNETIC waves ,SOUND waves ,SIGNAL processing ,SYNTHETIC aperture radar ,BANDWIDTHS - Abstract
This paper follows a detection-theoretic approach for using synthetic-aperture measurements, made at multiple moving passive receivers, in order to form an image showing the locations of stationary sources that are radiating unknown electromagnetic or acoustic waves. The paper starts with a physics-based model for the propagating fields, and, following the general approach of McWhorter et al (2023 arXiv:2302.06816, IEEE Open J. Signal Process. 4 437–51), derives a detection statistic that is used for the image formation. This detection statistic is a quadratic function of the data. Each point in the scene is tested as a possible hypothesized location for a source, and the detection statistic is plotted as a function of location. Because this image formation process is nonlinear, the standard linear methods for determining resolution cannot be applied. This paper shows how to analyze the detection image by first writing the noiseless image as a coherent sum of shifted complex ambiguity functions of the source waveform. The paper then develops a technique for calculating image resolution; resolution is found to depend on the sensor-source geometry and also on the properties (bandwidth and temporal duration) of the source waveform. Optimal filtering of the image is given, but a simple example suggests that optimal filtering may have little effect. Analysis is also given for the case in which multiple sources are present. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Ground moving target detection and tracking based on generalized SAR processing and change detection (Invited Paper)
- Author
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Edmund G. Zelnio, LeRoy A. Gorham, and Michael J. Minardi
- Subjects
Synthetic aperture radar ,business.industry ,Moving target indication ,law.invention ,Space-time adaptive processing ,Geography ,Ground speed ,law ,Radar imaging ,Computer vision ,Artificial intelligence ,Radar ,Focus (optics) ,business ,Change detection - Abstract
A unified way of detecting and tracking moving targets with a SAR radar called SAR-MTI is presented. SAR-MTI differs from STAP or DPCA in that it is a generalization of SAR processing and can work with only a single phase center. SAR-MTI requires formation of a series of images assuming different sensor ground speeds, from vs-vtmax to vs+vtmax, where vs is the actual sensor ground speed and vtmax is the maximum target speed of interest. Each image will capture a different set of target velocities, and the complete set of images will focus all target speeds less than a desired maximum speed regardless of direction and target location. Thus the 2-dimensional SAR image is generalized to a 3-dimensional cube or stack of images. All linear moving targets less than the desired speed will be focused somewhere in the cube. The third dimension represents the along track velocity of the mover which is a piece of information not available to standard airborne MTI. A mover will remain focused at the same place within the cube as long as the motion of the mover and the sensor remain linear. Because stationary targets also focus within the detection cube, move-stop-move targets are handled smoothly and without changing waveforms or modes. Another result of this fact is that SAR-MTI has no minimum detectable velocity. SAR-MTI has an inherent ambiguity because the four-dimensions of target parameters (two dimensions in both velocity and position) are mapped into a three-dimensional detection space. This ambiguity is characterized and methods for resolving the ambiguity for geolocation are discussed. The point spread function in the detection cube is also described.
- Published
- 2005
41. A comparative assessment on the use of SAR and high-resolution optical images in ocean dynamics studies An updated version of a paper originally presented at Oceans from Space 'Venice 2000' Symposium , Venice, Italy, 9-13 October 2000.
- Author
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Gagliardini, Domingo A. and Colón, Pablo Clemente
- Subjects
- *
SYNTHETIC aperture radar , *OPTICAL images , *AZIMUTH , *IMAGING systems , *OCEAN color , *WATER quality - Abstract
A comparison of Synthetic Aperture Radar (SAR) images acquired by the ERS-2 and RADARSAT-1 satellites with Landsat Thematic Mapper (TM) images acquired close in time is presented. Similarities and differences on the kind of ocean information they provide are discussed. The images were acquired over the Brazil-Malvinas (Falkland) Confluence under different solar elevation and azimuth angles. Ocean features observed by both types of sensors are discussed. These observations show that (1) at high solar angles, sun glint prevails over upwelled water-leaving radiance resulting in optical images that tend to provide dynamical information similar to that obtained from SAR imagery and (2) at low solar zenith and azimuth angles, upwelled radiation tends to prevail over sun glint, providing typical ocean colour and water quality information that can still complement and aid in the interpretation of SAR observations. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
42. Observations of wind and ocean wave fields using ERS Synthetic Aperture Radar imagery An updated version of a paper originally presented at Oceans from Space 'Venice 2000' Symposium , Venice, Italy, 9-13 October 2000.
- Author
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Carolis, Giacomo De, Parmiggiani, Flavio, and Arabini, Elena
- Subjects
- *
SYNTHETIC aperture radar , *OCEAN waves , *WIND speed measurement , *BACKSCATTERING , *IMAGING systems - Abstract
The aim of the research reported here is to evaluate Synthetic Aperture Radar (SAR) capability to estimate the wind vector and associated directional wave spectrum. Two ERS-2 SAR images of the Mediterranean Sea, one over the Sicily Channel and one over the Ligurian Sea, were selected as case studies. Wind speed was estimated using SAR calibrated backscatter response, in conjunction with empirically derived ERS scatterometer models such as CMOD4 and CMOD-IFREMER. The predictions of these models were then compared with the actual sea surface wave spectra either provided by in situ measurements or resulting from the inversion of the SAR image spectrum. SAR-detected effects of both wind and wave features, induced either by atmospheric boundary layer instability or by land shadowing, were also used as reliable indicators of wind direction. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
43. Internal wave study in the South China Sea using Synthetic Aperture Radar (SAR) An updated version of a paper originally presented at Oceans from Space 'Venice 2000' Symposium , Venice, Italy, 9-13 October 2000.
- Author
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Liu, A. K. and Hsu, M. K.
- Subjects
- *
INTERNAL waves , *OCEAN waves , *SYNTHETIC aperture radar , *IMAGING systems ,KUROSHIO - Abstract
Internal wave distribution maps have been compiled from more than one hundred ERS-1/2, RADARSAT and Space Shuttle SAR images in the South China Sea (SCS) from 1993 to 2000. Based on these distribution maps, most of the internal waves in the north-east part of the SCS were propagating westward. The wave crest can be as long as 200 km with an amplitude of 100 m, due to strong current from the Kuroshio branching out into the SCS. In a recent SCS internal wave study, moorings were deployed in April 1999 and 2000. Simultaneous SAR coverage from ERS-2 and RADARSAT were also collected. The ERS-2 high-resolution SAR images collected from the Taiwan ground station were processed in near real-time to coordinate the field test. SAR data are then used to compare with mooring data. SAR data and Acoustic Doppler Current Profiler (ADCP) data show internal solitons induced by the semi-diurnal tides with a wave speed of 2.4 m s -1 . [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
44. Clean seas: a North Sea test site An updated version of a paper originally presented at Oceans from Space 'Venice 2000' Symposium , Venice, Italy, 9-13 October 2000.
- Author
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Snaith, Helen M., Gade, Martin, W. Jolly, Gordon, Mangin, Antoine, Barale, Vittorio, Rud, Ove, and Ishii, Miho
- Subjects
- *
ARTIFICIAL satellites , *MARINE pollution monitoring , *SYNTHETIC aperture radar , *CHLOROPHYLL , *REMOTE sensing , *RADIOMETERS , *EARTH (Planet) - Abstract
The Clean Seas project focused on the role that existing Earth observing satellites might play in monitoring marine pollution. Results are presented here from August 1997, for the North Sea test site, using sea surface temperature (SST), colour and synthetic aperture radar (SAR) images in conjunction with a hydrodynamic model. There was good correlation between data sources, e.g. between SST and ERS-2 SAR images. Both datasets showed the development of fine plume structures close to the Rhine outflow, apparently associated with the outflow, and possibly caused by tidal pulsing of the Rhine Plume. The model reproduced general temperature and sediment distributions well, but fine structures were not reproduced. Model sediment distribution patterns were verified using 'chlorophyll concentration' data from colour sensors, representative of sediment concentration in turbid water. In conjunction with the visible channels of the Advanced Very High Resolution Radiometer and Along-Track Scanning Radiometer, they give an uncalibrated measure of the sediment load. The model gives a more complete picture of the temporal dispersion of the Rhine Plume over time than is evident from the remotely sensed data alone. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
45. Generation of internal solitary waves in the Sulu Sea and their refraction by bottom topography studied by ERS SAR imagery and a numerical model An updated version of a paper originally presented at Oceans from Space 'Venice 2000' Symposium , Venice, Italy, 9-13 October 2000.
- Author
-
Zeng, K. and Alpers, W.
- Subjects
- *
SOLITONS , *WAVE packets , *SYNTHETIC aperture radar , *WATER waves , *KORTEWEG-de Vries equation - Abstract
ERS-2 SAR images acquired over the Sulu Sea reveal that there are at least three areas where internal solitary waves are generated: (1) at the sill between Dok Kan Island and Pearl Bank; (2) at the sill between Pearl Bank and Talantam Shoal; and (3) at the sill between Talantam Shoal and Sentry Bank. It is observed that the internal solitary waves generated at different source regions merge into a single solitary wave system. When the solitary waves propagate into shallow water, the distance between the solitary waves in a wave packet decreases. Furthermore, when the water depth decreases in the direction of the soliton's crest line, the crest line is bent towards the shallow water region. These observational facts are explained by a wave refraction model which is based on the Korteweg-de Vries equation which is also valid for large amplitude internal solitary waves provided the pycnocline is sufficiently broad. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
46. Fine-scale features on the sea surface in SAR satellite imagery - Part 2: Numerical modeling.
- Author
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Matt, S., Fujimura, A., Soloviev, A., Rhee, S. H., and Romeiser, R.
- Subjects
SYNTHETIC aperture radar ,SEA surface microlayer ,REMOTE-sensing images ,NUMERICAL analysis ,MATHEMATICAL models of hydrodynamics ,COMPUTATIONAL fluid dynamics ,COMPUTER simulation - Abstract
With the advent of the new generation of SAR satellites, it has become possible to resolve fine-scale features on the sea surface on the scale of meters. The proper identification of sea surface signatures in SAR imagery can be challenging, since some features may be due to atmospheric distortions (gravity waves, squall lines) or anthropogenic influences (slicks), and may not be related to dynamic processes in the upper ocean. In order to improve our understanding of the nature of fine-scale features on the sea surface and their signature in SAR, we have conducted high-resolution numerical simulations combining a three-dimensional non-hydrostatic computational fluid 10 dynamics model with a radar imaging model. The surface velocity field from the hydrodynamic model is used as input to the radar imaging model. The combined approach reproduces the sea surface signatures in SAR of ship wakes, low density plumes, and internal waves in a stratified environment. The numerical results are consistent with observations reported in a companion paper of in-situ measurements during SAR 15 satellite overpasses. Ocean surface and internal waves are also known to produce a measurable signal in the ocean magnetic field. This paper explores the use of computational fluid dynamics to investigate the magnetic signatures of oceanic processes. This potentially provides a link between SAR signatures of transient ocean dynamics and magnetic field fluctuations in the ocean. We suggest that combining SAR imagery 20 with data from ocean magnetometers may be useful as an additional maritime sensing method. The new approach presented in this work can be extended to other dynamic processes in the upper ocean, including fronts and eddies, and can be a valuable tool for the interpretation of SAR images of the ocean surface. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
47. A New Compact Triple-Band Triangular Patch Antenna for RF Energy Harvesting Applications in IoT Devices.
- Author
-
Benkalfate, Chemseddine, Ouslimani, Achour, Kasbari, Abed-Elhak, and Feham, Mohammed
- Subjects
- *
ENERGY harvesting , *ANTENNAS (Electronics) , *ELECTRONIC equipment , *OMNIDIRECTIONAL antennas , *PERMITTIVITY , *WIRELESS LANs , *SYNTHETIC aperture radar , *RADIO frequency - Abstract
This work proposes a new compact triple-band triangular patch antenna for RF energy harvesting applications in IoT devices. It is realized on Teflon glass substrate with a thickness of 0.67 mm and a relative permittivity of 2.1. Four versions of this antenna have been designed and realized with inclinations of 0°, 30°, 60° and 90° to study the impact of the tilting on their characteristics (S11 parameter, radiation pattern, gain) and to explore the possibilities of their implementation in the architectures of electronic equipment according to the available space. The antenna is also realized on waterproof paper with a thickness of 0.1 mm and a relative permittivity of 1.4 for biomedical domain. All the antennas (vertical antenna, tilted antennas and antenna realized on waterproof paper) have a size of 39 × 9 mm2 and cover the 2.45 GHz and 5.2 GHz Wi-Fi bands and the 8.2 GHz band. A good agreement is obtained between measured and simulated results. Radiation patterns show that all the antennas are omnidirectional for 2.45 GHz and pseudo-omnidirectional for 5.2 GHz and 8.2 GHz with maximum measured gains of 2.6 dBi, 4.55 dBi and 6 dBi, respectively. The maximum measured radiation efficiencies for the three antenna configurations are, respectively, of 75%, 70% and 72%. The Specific Absorption Rate (SAR) for the antenna bound on the human body is of 1.1 W/kg, 0.71 W/kg and 0.45 W/kg, respectively, for the three frequencies 2.45 GHz, 5.2 GHz and 8.2 GHz. All these antennas are then applied to realize RF energy harvesting systems. These systems are designed, realized and tested for the frequency 2.45 GHz, −20 dBm input power and 2 kΩ resistance load. The maximum measured output DC power is of 7.68 µW with a maximum RF-to-DC conversion efficiency of 77%. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
48. The MET Norway Ice Service: a comprehensive review of the historical and future evolution, ice chart creation, and end user interaction within METAREA XIX.
- Author
-
Copeland, William, Wagner, Penelope, Hughes, Nick, Everett, Alistair, and Robertsen, Trond
- Subjects
SEA ice ,INFORMATION storage & retrieval systems ,GEOGRAPHIC information systems ,SYNTHETIC aperture radar ,COASTS ,OFFICES ,DATA libraries - Abstract
The MET Norway Ice Service (NIS) celebrated its fiftieth year as a formal operational sea ice information provider in 2020. Prior to the 1970's, support to navigation had started off with ad-hoc observations from coastal stations on Svalbard in the 1930's, before developing as a research programme in the 1960's. Activity in the region has steadily increased, and now the NIS also supports a large number of research, tourist, and resource exploration vessels, in addition to the ice chart archive being a resource for climate change research. The Ice Service has always been at the forefront in the use of satellite Earth Observation technologies, beginning with the routine use of optical thermal infrared imagery from NASA TIROS and becoming a large user of Canadian RADARSAT-2 Synthetic Aperture Radar (SAR), and then European Copernicus Sentinel-1, in the 2000's and 2010's. Initially ice charts were a weekly compilation of ice information using cloud-free satellite coverage, aerial reconnaissance, and in situ observations, drawn on paper at the offices of the Norwegian Meteorological Institute (MET Norway) in Oslo. From 1997 production moved to the Tromsø office using computer-based Geographical Information System (GIS) software and the NIS developed the ice charting system Bifrost. This allowed the frequency of production to be increased to every weekday, with a greater focus on detailed sea ice concentrations along the ice edge and coastal zones in Eastern Greenland and in the Svalbard fjords. From 2010, the NIS has also provided a weekly austral summer ice chart for the Weddell Sea and Antarctic Peninsula. To further develop its capabilities, NIS engages in a number of national and international research projects and led the EU Horizon 2020 project, Key Environmental monitoring for Polar Latitudes and European Readiness (KEPLER). This paper summarises the overall mandate and history of the NIS, and its current activities including the current state of routine production of operational ice charts at the NIS for maritime safety in both the Arctic and Antarctic, and future development plans. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. An Efficient and Accurate Ground-Based Synthetic Aperture Radar (GB-SAR) Real-Time Imaging Scheme Based on Parallel Processing Mode and Architecture.
- Author
-
Tan, Yunxin, Li, Guangju, Zhang, Chun, and Gan, Weiming
- Subjects
SYNTHETIC aperture radar ,RADAR signal processing ,IMAGING systems ,GRAPHICS processing units ,PARALLEL processing ,SYNTHETIC apertures - Abstract
When performing high-resolution imaging with ground-based synthetic aperture radar (GB-SAR) systems, the data collected and processed are vast and complex, imposing higher demands on the real-time performance and processing efficiency of the imaging system. Yet a very limited number of studies have been conducted on the real-time processing method of GB-SAR monitoring data. This paper proposes a real-time imaging scheme based on parallel processing models, optimizing each step of the traditional ω K imaging algorithm in parallel. Several parallel optimization schemes are proposed for the computationally intensive and complex interpolation part, including dynamic parallelism, the G r o u p - N s t r e a m processing model, and the F t h r e a d - G r o u p - N s t r e a m processing model. The F t h r e a d - G r o u p - N s t r e a m processing model utilizes F t h r e a d , G r o u p , and N s t r e a m for the finer-grained processing of monitoring data, reducing the impact of the nested depth on the algorithm's performance in dynamic parallelism and alleviating the issue of serial execution within the G r o u p - N s t r e a m processing model. This scheme has been successfully applied in a synthetic aperture radar imaging system, achieving excellent imaging results and accuracy. The speedup ratio can reach 52.14, and the relative errors in amplitude and phase are close to 0, validating the effectiveness and practicality of the proposed schemes. This paper addresses the lack of research on the real-time processing of GB-SAR monitoring data, providing a reliable monitoring method for GB-SAR deformation monitoring. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Phase Calibration in Holographic Synthetic Aperture Radar: An Innovative Method for Vertical Shift Correction.
- Author
-
Huang, Fengzhuo, Feng, Dong, Hua, Yangsheng, Ge, Shaodi, He, Junhao, and Huang, Xiaotao
- Subjects
CALIBRATION ,SYNTHETIC aperture radar - Abstract
Holographic synthetic aperture radar (HoloSAR) introduces a cutting-edge three-dimensional (3-D) imaging mode to the field of synthetic aperture radar (SAR), enriching the scattering information of targets by observing them across multiple spatial dimensions. However, independent phase errors among baselines, such as those caused by platform jitter and measurement inaccuracies, pose significant challenges to imaging quality. The phase gradient autofocus (PGA) method effectively estimates phase errors, but struggles to accurately estimate the linear component, causing vertical shift in HoloSAR subaperture imaging result. Therefore, this paper proposes a PGA-based phase error compensation method for HoloSAR to address the vertical shift issue caused by linear phase errors. This method can achieve phase error correction in both the echo domain and image domain with enhanced efficiency. Experimental results of simulated targets and real data from the GOTCHA system demonstrate the effectiveness and practicality of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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