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algorithm for Sea Surface Wind Retrieval From TerraSAR-X and TanDEM-X Data

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2014年第5期52卷 2928-2939页

作者： Li, Xiao-Ming Lehner, Susanne German Aerosp Ctr DLR Remote Sensing Technol Inst D-82234 Wessling Germany

A geophysical model function (GMF), which is denoted by XMOD2, is developed to retrieve sea surface wind field from X-band TerraSAR-X/TanDEM-X (TS-X/TD-X) data. In contrast to the previously developed XMOD1, XMOD2 consists of a nonlinear GMF, and thus, it depicts the difference between upwind and downwind of the sea surface backscatter in X-band synthetic aperture radar (SAR) imagery. By exploiting 371 collocations with in situ buoy measurements that are used as the tuning data set together with analysis wind model results, the retrieved TS-X/TD-X sea surface wind speed using XMOD2 shows a close agreement with buoy measurements with a bias of -0.32 m/s, a root-mean-square error (RMSE) of 1.44 m/s, and a scatter index (SI) of 16.0%. Further validation using an independent data set of 52 cases shows a bias of -0.17 m/s, an RMSE of 1.48 m/s, and an SI of 17.0% comparing with buoy measurements. To apply XMOD2 to TS-X/TD-X data acquired at HH polarization, we validate three X-band SAR polarization ratio models that were tuned using TS-X dual-polarization data by comparing the retrieved sea surface wind speed with buoy measurements.

关键词： algorithm development sea surface wind X-band synthetic aperture radar (SAR)

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Near-lossless image compression techniques

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JOURNAL OF ELECTRONIC IMAGING 1998年第3期7卷 486-494页

作者： Ansari, R Memon, N Ceran, E Univ Illinois Dept EECS MC 154 Chicago IL 60607 USA No Illinois Univ Dept Comp Sci De Kalb IL 60115 USA

Predictive and multiresolution techniques for near-lossless image compression based on the criterion of maximum allowable deviation of pixel values are investigated. A procedure for near-lossless compression using a modification of lossless predictive coding techniques to satisfy the specified tolerance is described. Simulation results with modified versions of two of the best lossless predictive coding techniques known, CALIC and JPEG-LS, are provided. Application of lossless coding based on reversible transforms in conjunction with prequantization is shown to be inferior to predictive techniques for near-lossless compression. A partial embedding two-layer scheme is proposed in which an embedded multiresolution coder generates a lossy base layer, and a simple but effective context-based lossless coder codes the difference between the original image and the lossy reconstruction. Results show that this lossy plus near-lossless technique yields compression ratios close to those obtained with predictive techniques, while providing the feature of a partially embedded bit-stream. (C) 1998 SPIE and IS&T. [S1017-9909(98)00203-7].

关键词： Image compression Transform theory Quantization Computer programming Image processing Tolerancing algorithm development Information visualization Medical imaging Visualization

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Recent Advancements in the DIII-D Plasma Control System

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IEEE TRANSACTIONS ON PLASMA SCIENCE 2024年第9期52卷 3535-3541页

作者： Margo, M. W. Shen, H. Penaflor, B. Sammuli, B. Piglowski, D. Eldon, D. Barr, J. Orozco, D. Anand, H. Moser, A. Cho, E. Pederson, T. Le, J. Lasnier, C. Erickson, K. Reed, R. Gen Atom San Diego CA 92121 USA Lawrence Livermore Natl Lab Livermore CA 94550 USA Princeton Plasma Phys Lab Princeton NJ 08540 USA

The plasma control system (PCS) is a critical application required for daily operation of the DIII-D tokamak. Continuous expansion and upgrades to its hardware and software require a careful balance between the need to sustain high operations availability and the introduction of new real-time (RT) acquisition and control schemes. A number of new and improved diagnostics and controls have been added to the PCS. Expansion of the Upper Divertor Viewing (UDV) bolometer diagnostic now covers the tokamak upper divertor region and 8 new UDV channels have been added to the PCS data suite. To improve protection of the vessel, heat-flux and surface temperature control using real time infrared (IRTV) diagnostics have been successfully demonstrated. Neural network models have been added to the system to support experiments in disruption avoidance. In response to the increasing demand for software enhancements during operations, a testbed that closely mirrors the production hardware and software has been recently constructed and commissioned. It significantly increases the variety of testing that can be performed. Therefore, it is now possible to simultaneously operate DIII-D while validating new control algorithms for future experiments. In conjunction with an expansion of regular code reviews, the deployment of the testbed has resulted in greater reliability even with an increasing number and frequency of updates. Details of the specific hardware and software enhancements made along with improvements to testing and software quality assurance will be presented.

关键词： algorithm development machine learning plasma control

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Using MERIS full resolution data to monitor coastal waters - A case study from Himmerfjarden, a fjord-like bay in the northwestern Baltic Sea

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REMOTE SENSING OF ENVIRONMENT 2008年第5期112卷 2284-2300页

作者： Kratzer, Susanne Brockmann, Carsten Moore, Gerald Stockholm Univ Dept Syst Ecol SE-10691 Stockholm Sweden Stockholm Univ Dept Phys Geog & Quaternary Geol SE-10691 Stockholm Sweden Brockmann Consult D-21502 Geesthacht Germany Plymouth Marine Lab Plymouth PL1 3DH Devon England

In this paper we investigate if MERIS full resolution (FR) data (300 m) is sufficient to monitor changes in optical constituents in Himmerfjarden, a fjord-like, north-south facing bay of about 30 km length and 4 km width. The MERIS FR products were derived using a coastal processor (FUB Case-2 Plug-In). We also compared the performance between FUB and standard processor (MEGS 7.4), using reduced resolution (RR) data (1 km resolution) from the open Baltic Sea, and compared the products to sea-truthing data. The optical variables measured for sea-truthing were chlorophyll, suspended particulate matter (SPM), as well as coloured dissolved organic matter (CDOM, also termed yellow substances), and the spectral diffuse attenuation coefficient, K-d(490). The comparison of the RR data to the sea-truthing data showed that, in the open Baltic Sea, the MERIS standard processor overestimated chlorophyll by about 59%, and SPM by about 28%, and underestimated yellow substance by about 81%, whereas the FUB processor underestimated SPNI by about 60%, CDOM by about 78%, and chlorophyll a by about 56%. The FUB processor showed a relatively high precision for all optical components (standard deviation: 6-18%), whereas the precision for the MEGS 7.4 was rather low (standard deviation: 43-73%), except for CDOM (standard deviation: 13%). The analysis of the FR data showed that all FR level 2 water products derived from MERIS followed a polynomial decline in concentration when moving off-shore. The distribution of chlorophyll and SPM was best described by a 2nd order polynomial, and the distribution of CDOM by a 3rd order polynomial, verifying the diffusional model described in Kratzer and Tell [Kratzer, S. and Tett, P. (in press). Using bio-optics to investigate the extent of coastal waters - a Swedish case study. Hydrobiologia.]. A new Kd(490) and Secchi depth algorithm based on MERIS channel 3 (490 nm) and channel 6 (620 nm) each was derived from radiometric sea-truthing data (TACCS, S

关键词： MERIS FR data Baltic Sea coastal zone spectral diffuse attenuation coefficient K-d(490) Secchi depth algorithm development

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RAPAC - A HIGH-SPEED IMAGE-PROCESSING SYSTEM

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IEE PROCEEDINGS-E COMPUTERS AND DIGITAL TECHNIQUES 1987年第1期134卷 39-46页

作者： ELPHINSTONE, AC HERON, AP HOBSON, GS HOUGHTON, A LAU, MK POWELL, AR SEED, L TOZER, RC Department of Electronic & Electrical Engineering University of Sheffield Sheffield UK

The paper describes the design and operation of a real-time image processing system and outlines one of its application areas. The system consists of a dedicated hardware processor called RAPAC (a reconfigurable attached processor architecture for convolution) and a host computer which is used for algorithm development and RAPAC control. RAPAC uses hardware processor units and multiple image memories, in a software controlled architecture, to process 5 MHz streams of pixel data. This processing rate allows it to process a 256 × 256 pixel image in 20 ms, one field time of a standard TV camera. The result is either a new 256 × 256 pixel image generated from the old image or a reduced data set which describes attributes of features in the image. These attributes are used by the host computer to calculate a decision output concerning the content of the image.

关键词： RAPAC Computer architecture multiple image memories reconfigurable attached processor architecture for convolution computer architecture algorithm development software controlled architecture pixel data decision output Digital signal processing computerised picture processing host computer dedicated hardware processor high-speed image-processing system

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Ranked data analysis of a gamut-mapping experiment

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JOURNAL OF ELECTRONIC IMAGING 2001年第2期10卷 399-408页

作者： Millen, BA Bunge, J Handley, JC Ohio State Univ Dept Stat Columbus OH 43210 USA Cornell Univ Dept Social Stat Ithaca NY 14853 USA Xerox Res & Technol Digital Imaging Technol Ctr Webster NY 14580 USA

We analyze data from a gamut-mapping experiment using several statistical procedures for ranked data. In this experiment six gamut-mapping algorithms were applied to six different images and the results were ranked by 31 judges according to how well the images matched an original. We fitted two distance-based statistical models to the data: both analyses showed that aggregate preference among the six algorithms depended on the image viewed. Based on the first model we classified the images into four classes or clusters. We applied unidimensional unfolding, a technique from mathematical psychology, to extract latent reference frames upon which judges plausibly ordered the algorithms. Four color experts gave interpretations of the derived reference frames. We used the second model to generate confidence sets for the consensus rankings, and another cluster analysis. (C) 2001 SPIE and IS&T.

关键词： Data modeling Statistical analysis Mathematical modeling Statistical modeling Data analysis Distance measurement Analytical research algorithm development Data centers Statistical methods

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algorithm developed for dynamic quantification of coal consumption for and emission from rural winter heating

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SCIENCE OF THE TOTAL ENVIRONMENT 2020年 737卷 139762-139762页

作者： Zhang, Yuzhe Zhi, Guorui Guo, Sicong Jin, Wenjing Wang, Lei Du, Jinhong Cheng, Miaomiao Xue, Zhigang Xu, Yisheng Shi, Rong Lu, Yajing Dang, Hongyan Yang, Wen Zhang, Peng Zhang, Baojun Wu, Jianjun Shi, Zhihai Liu, Bin Zhang, Yi Gu, Xiaotian Liu, Na Gu, Tao Zhu, Yinhua Liu, Cheng Dong, Hui Li, Shuyuan Chinese Res Inst Environm Sci State Key Lab Environm Criteria & Risk Assessment Beijing 100012 Peoples R China China Univ Petr Coll Sci Beijing 102249 Peoples R China Taiyuan Univ Technol Coll Chem & Chem Engn Taiyuan 030024 Peoples R China Ocean Univ China Coll Informat Sci & Engn Qingdao 266100 Peoples R China Hebei Prov Acad Ecol Environm Sci Shijiazhuang 050037 Hebei Peoples R China Qingdao Agr Univ Coll Mech & Elect Engn Qingdao 266109 Peoples R China Tangshan Inst Environm Planning Sci Tangshan 063000 Peoples R China Tangshan Bur Ecol & Environm Dept Atmospher Environm Tangshan 301501 Peoples R China Tangshan Bur Ecol & Environm Hangu Adm Zone Branch Tangshan 301501 Peoples R China Peoples Govt Hanfeng Town Tangshan 301501 Peoples R China Changji Hui Autonomous Prefecture Environm Monito Changji 831100 Peoples R China Changji Hui Autonomous Prefecture Bur Ecol & Envi Fukang Branch Changji 831500 Peoples R China Changji Santun River Basin Management Div Changji 831100 Peoples R China

Coal-dominated winter heating practices in China are largely accepted to be a leading cause of winter haze in the region though the amount of coal for heating is actually much lower than for power generation or industrial process. However, little is known about how the total rural coal weight in a region could be attributed to real time (e.g., daily) patterns, limiting the understanding of dynamic impacts of coal emissions and the adoption of timely measures against predicted haze. Considering that winter heating essentially protects against cold temperatures, coal burning strength may be related to the temperatures that people experience. A field study was organized to test the validity of this hypothesis. A system was designed to continuously monitor every instance of coal addition, and coal consumption on any given day for a whole village (W-DAY) was calculated by summating all the additions. Meanwhile, a new term, composite temperature (T-COM), which incorporates a few weather-related elements, was introduced to represent cold temperatures that individuals experience. It was found that W-DAY and T-COM presented opposite variations, and a negative linear correlation was observed (W-DAY=-0.75T(COM) + 11.86, R-2 = 0.75), revealing the feasibility of estimating coal consumption on a certain day (W-DAY) based on weather data (T-COM) for a given village. An extensive form of the algorithm for any area of interest (e.g., a district, city, or province) can be expressed as W-DAY=(-0.75T(COM) + 11.86)center dot N-H/834, where N-H denotes the number of households in a region. This algorithm reflects the essence of winter heating (to resist cold temperatures), and therefore its logic is highly likely to be useful for any countries of the world regardless of what forms of energy used (coal or other energy forms) provided the energy involved is unexceptionally used for winter heating, though there may be some uncertainties in estimated coal consumption due to multiple factors

关键词： Rural coal heating Coal consumption Real time quantification algorithm development Field study

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Interactive simulation and visualization

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COMPUTER 1999年第12期32卷 59-+页

作者： Johnson, C Parker, SG Hansen, C Kindlmann, GL Livnat, Y Univ Utah Ctr Sci Comp & Imaging Salt Lake City UT 84112 USA Univ Utah Dept Comp Sci Salt Lake City UT 84112 USA

Most researchers who perform data analysis and visualization do so only after everything else is finished, which often means that they don't discover errors invalidating the results of their simulation until postprocessing. A better approach would be to improve the integration of simulation and visualization into the entire process so that they can make adjustments along the way. This approach, called computational steering, is the capacity to control all aspects of the computational science pipeline. Recently, several tools and environments for computational steering have begun to emerge. These tools range from those that modify an application's performance characteristics, either by automated means or by user interaction, to those that modify the underlying computational application. A refined problem-solving environment should facilitate everything from algorithm development to application steering. The authors discuss some tools that provide a mechanism to integrate modeling, simulation, data analysis, and visualization.

关键词： algorithm development application performance characteristics application steering computational science computational steering data analysis data analysis data visualisation digital simulation interactive data visualization interactive simulation interactive systems modelling refined problem-solving environment

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Font clustering and cluster identification in document images

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JOURNAL OF ELECTRONIC IMAGING 2001年第2期10卷 418-430页

作者： Öztürk, S Sankur, B Abak, AT Bogazici Univ Dept Elect Elect Engn TR-80815 Bebek Turkey Marmara Res Ctr Informat Technol Res Inst Gebze Kocaeli Turkey

In this work clustering and recognition problem of fonts in document images is addressed. Various font features and their clustering behavior are investigated. Font clustering is implemented both from shape similarity or from OCR performance points of view. A font recognition algorithm is developed that can identify the font group or the individual font from which a text was created. (C) 2001 SPIE and IS&T.

关键词： Optical character recognition Raster graphics Detection and tracking algorithms algorithm development Feature extraction Binary data Image segmentation Databases Distance measurement Distortion

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An improved algorithm for the detection of plumes caused by natural or technological hazards using AVHRR imagery

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REMOTE SENSING OF ENVIRONMENT 2007年第4期108卷 393-406页

作者： Chrysoulakis, N. Herlin, I. Prastacos, P. Yahia, H. Grazzini, J. Cartalis, C. Fdn Res & Technol Hellas Inst Appl & Computat Math Vassilika VoutonPOB 1358 Iraklion 71110 Crete Greece INRIA Rocquencourt Inst Natl Rech Informat & Automat F-78153 Le Chesnay France European Commiss DG Joint Res Ctr Inst Environm & Sustainabil Spatial Data Infrastruct Unit I-21020 Ispra VA Italy Univ Athens Dept Phys GR-15784 Athens Greece

Fires caused by natural or technological disasters emit large amounts of smoke which, once formed into plumes, may affect the human health and the environment. Satellite remote sensing data provide an effective tool to achieve detection and monitoring of these plumes over large areas on a routine basis. Discrimination of plumes on satellite images is a prerequisite to study and retrieve physical, chemical and optical properties of emitted smoke. An improved algorithm for the detection of plumes caused by natural or technological hazards using AVHRR imagery is presented in this study. The method is based on a multi-temporal and multi-spectral change detection algorithm. It is performed in two main steps: a) appropriate spectral and spatial filters are applied on the images acquired before and after a fire event in visible and near-infrared ranges in order to extract the core of the plume;b) a criterion on spectral information is defined as an homogeneity measure that enables, through a modified version of the region-growing method, the spatial expansion of the detected core to include the complete area covered by the plume. Through this approach, a pixel is identified as a plume pixel if it is "close" to the core plume pixels in both spatial and spectral spaces. The algorithm was developed and calibrated using AVHRR images acquired over Spain before and during a major forest fire event on July 16, 2005. It was applied using past events of natural and technological hazards in several locations to ensure its global applicability and robustness. The algorithm produced accurate results in all cases of plumes, either in natural or in technological fire events. Three application cases are presented in this study: A major fire in an industrial installation in London (December 11, 2005), a major fire in Baghdad during the recent war in Iraq (April 1, 2003) and a forest fire in California (September 29, 2005). (c) 2006 Elsevier Inc. All rights reserved.

关键词： plume detection and monitoring algorithm development natural hazards technological accidents changed detection region growing

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