SAR Methods Research Articles

A New Calibration Method of Airborne Interferometric SAR

Abstract. The accuracy of system parameters is one of the key factors that limit the precision of DEM from airborne dual-antenna InSAR, so the interferometric calibration is of great significance. The traditional calibration method establishes the sensitivity equations to solve the different calibration parameters biases. This paper presents a new calibration method to improve the algorithm stability and suit for mass production. It introduces sensitivity analysis of every interferometric parameter and establishes a new model based on sensitivity equations. Finally, a set of airborne interferometric SAR data are adopted to do the experiment to illustrate the availability of the new method.

Classification of High Resolution Sar Imagery Using Local Indicators of Spatial Association

In this paper, we will propose a novel classification method of high-resolution SAR using local autocorrelation and Support Vector Machines (SVM) classifier. The commonly applied spatial autocorrelation indexes, called Moran's Index; Geary's Index, Getis's Index, will be used to depict the feature of the land-cover. Then, the SVM based on these indexes will be applied as the high-resolution SAR classifier. A Cosmo-SkyMed scene in ChengDu city, China is used for our experiment. It is shown that the method proposed can lead to good classification accuracy.

Iterative Bilateral Filtering of Polarimetric SAR Data

In this paper, we introduce an iterative speckle filtering method for polarimetric SAR (PolSAR) images based on the bilateral filter. To locally adapt to the spatial structure of images, this filter relies on pixel similarities in both spatial and radiometric domains. To deal with polarimetric data, we study the use of similarities based on a statistical distance called Kullback-Leibler divergence as well as two geodesic distances on Riemannian manifolds. To cope with speckle, we propose to progressively refine the result thanks to an iterative scheme. Experiments are run over synthetic and experimental data. First, simulations are generated to study the effects of filtering parameters in terms of polarimetric reconstruction error, edge preservation and smoothing of homogeneous areas. Comparison with other methods shows that our approach compares well to other state of the art methods in the extraction of polarimetric information and shows superior performance for edge restoration and noise smoothing. The filter is then applied to experimental data sets from ESAR and FSAR sensors (DLR) at L-band and S-band, respectively. These last experiments show the ability of the filter to restore structures such as buildings and roads and to preserve boundaries between regions while achieving a high amount of smoothing in homogeneous areas.

Testing the standardized growth curve (SGC) to OSL dating coastal sediments from the south Bohai Sea, China

It has been suggested that the standardized growth curve (SGC) method can be used to accurately determinate equivalent dose (De) and reduce measurement time. However, different opinions regarding the applicability of the SGC method exist. In this paper, we evaluated quartz OSL SGCs of marine and coastal sediments of different grain sizes and different cores in the south Bohai Sea in China, and tested their applicability to the determination of De values. Our results suggested as follows: (1) The SGC method is applicable to both multiple- and single-aliquot regenerative-dose (MAR and SAR) protocols of OSL dating and efficiently provides reliable estimates of De. (2) Finesand quartz of different palaeodoses showed highly similar dose-response curves and an SGC was developed, but old samples using the SGC method have large uncertainties. (3) For coarse-silt quartz, two different types of dose-response curves were recorded: low-dose (≤60Gy) and high-dose (≥100Gy). The growth curves of low-dose quartz were similar to each other, facilitating the use of SGC in De estimations, but errors tended to be larger than those obtained in the SAR method. For high-dose (100–300Gy) quartz, the SGC was also found to be reliable, but there was large uncertainty in De (>300Gy) estimation. We suggest that SGC could be employed for the dating of marine and coastal sediments dating using either MAR or SAR OSL protocol and either fine-silt, coarse-silt or fine-sand quartz.

Deramping-based Imaging Method for Bistatic Forward-looking SAR

Abstract With the ability to resolve the ambiguity and higher azimuth resolution, bistatic forward-looking synthetic aperture radar (BFLSAR) imaging is strongly desirable in both navigation and safety landing for small platforms. However, due to the Doppler centroid variation along the range direction, azimuth spectrum will cross into the neighboring pulse repetition frequency (PRF) band causing severe azimuth ambiguity. Conventional frequency focusing method cannot directly used in this case. In this paper, deramping technique is employed to realize the coarse focusing and reduce the azimuth bandwidth, thus spectrum folding is mitigated. Incorporated secondary range compression, fine focusing is obtained. Simulation results validate the effectiveness of the proposed method.

OSL 연대측정을 통한 풍납토성 축조연대 산출

백제 한성기의 왕성으로 알려진 풍납토성의 축조연대는 고고학 분야의 대표적인 논쟁사항 중 하나이다. 이 연구에서는 풍납토성의 축조연대 편년을 위해 7 개의 토기 시료에 대하여 OSL 연대측정을 수행하였다. 연대측정에 앞서 TL/OSL 신호 관찰 및 절대영년도 평가, 재현성 평가를 수행한 결과, 풍납토성 토기 시료는 절대영년이 완벽히 이루어졌으며 고고선량은 <TEX>$220^{\circ}C$</TEX> 열전처리 온도의 단일시료재현법으로부터 신뢰도 높은 값이 산출되었다. 산출된 고고선량을 연간선량율로 나누어 풍납토성 토기 시료의 OSL 연대를 결정하였다. 풍납토성의 축조연대 편년을 위해 각 토기 시료의 OSL 연대와 고고학적 맥락, 14C 연대 등을 종합하여 판단한 결과, 풍납토성의 초축시점을 <TEX>$294{\pm}52$</TEX> yrs AD (<TEX>$1{\sigma}$</TEX> SE), 제 III 단계 증축을 <TEX>$328{\pm}30$</TEX> yrs AD (<TEX>$1{\sigma}$</TEX> SE), 최종성벽의 완성을 <TEX>$400{\pm}76$</TEX> yrs AD (<TEX>$1{\sigma}$</TEX> SE)로 비정하였다. 따라서 풍납토성은 서기 3세기 후반에 초축된 이후 475년 백제의 웅진천도 이전까지 여러 번의 중축 및 개축이 이루어졌음을 알 수 있었다. Construction era of Pungnabtoseong earthen wall is one of the most popular controversial issues in Korean archaeological research. For the evaluation of construction era, OSL dating was carried out using seven pottery pieces collected in each construction stage. From TL/OSL characteristics, and the results of absolute zeroing test and recovery test, it was proved that the pottery samples were completely bleached. The reliable paleodose was evaluated by using the SAR method with preheat at <TEX>$220^{\circ}C$</TEX>, and the pottery OSL age was determined from the ratio of paleodose to annual dose rate. Considering the resultant OSL ages, archaeological context and the related 14C ages, the first construction era was determined as <TEX>$294{\pm}52$</TEX> yrs AD (<TEX>$1{\sigma}$</TEX> SE). Also we found that the enlargement of construction stage III was <TEX>$328{\pm}30$</TEX> yrs AD (<TEX>$1{\sigma}$</TEX> SE) and final construction was finished within <TEX>$400{\pm}76$</TEX> yrs AD (<TEX>$1{\sigma}$</TEX> SE). Therefore, it is suggested that the construction of Pungnabtoseong earthen wall was firstly started in the late <TEX>$3^{rd}$</TEX> century AD and several enlargements and repairs had been carried out, before the transfer of the capital of Baekje dynasty to Woongjin (Gongju) at 475 AD.

SPASIAL DATA MINING MENGGUNAKAN MODEL SAR-KRIGING

The region of Indonesia is very sparse and it has a variation condition in social, economic and culture, so the problem in education quality at many locations is an interesting topic to be studied. Database used in this research is Base Survey of National Education 2003, while a spatial data is presented by district coordinate as a least analysis unit. The aim of this research is to study and to apply spatial data mining to predict education quality at elementary and junior high schools using SAR-Kriging method which combines an expansion SAR and Kriging method. Spatial data mining process has three stages. preprocessing, process of data mining, and post processing.For processing data and checking model, we built software application of Spatial Data Mining using SAR-Kriging method. An application is used to predict education quality at unsample locations at some cities at DIY Province. The result shows that SAR-Kriging method for some cities at DIY for elementary school has an average percentage error 6.43%. We can conclude that for elementary school, SAR-Kriging method can be used as a fitted model. Keywords— Expansion SAR, SAR-Kriging, quality education

Discovery of pyrrolidine-based β-secretase inhibitors: Lead advancement through conformational design for maintenance of ligand binding efficiency

We have developed a novel series of pyrrolidine derived BACE-1 inhibitors. The potency of the weak initial lead structure was enhanced using library-based SAR methods. The series was then further advanced by rational design while maintaining a minimal ligand binding efficiency threshold. Ultimately, the co-crystal structure was obtained revealing that these inhibitors interacted with the enzyme in a unique fashion. In all, the potency of the series was enhanced by 4 orders of magnitude from the HTS lead with concomitant increases in physical properties needed for series advancement. The progression of these developments in a systematic fashion is described.

A Novel High Resolution Imaging Method for the Missile-borne SAR

A Novel High Resolution Imaging Method for the Missile-borne SAR

Assessment of diagnostic tests for evaluating the reliability of SAR D e values from polymineral and quartz fine grains

In this study, we applied optically stimulated luminescence (OSL) dating to two fine grain sediment samples collected at Jeongokri, Korea. A single aliquot regenerative dose (SAR) procedure was applied to both polymineral grains and to chemically isolated (H 2SiF 6) quartz grains of 4–11 μm diameter. For polymineral fine grains, the OSL IR depletion ratio and the equivalent dose (D e) plateau test appear to be equally sensitive indicators of appropriate IR stimulation time for use in the ‘double SAR’ protocol. Additionally, the OSL IR depletion ratio test gives an indication of the relative mineral composition of the samples, hence providing an assessment of the likelihood of obtaining a quartz-dominated [post-IR] OSL signal. Use of higher preheat temperatures would assist in thermally eroding the non-quartz component of the [post-IR] OSL signal from polyminerals. For the quartz fine grains, data from both natural D e determinations and laboratory dose recovery tests are required to identify the appropriate preheat temperatures for dating, due to problems of thermal transfer. This phenomenon is particularly exaggerated for these samples due to the large D e values (≥350 Gy) and hence low slope of the dose–response curve. The double SAR method cannot be applied ubiquitously, even after careful and rigorous study of one sample from a section. Quartz OSL dating using a range of preheat temperatures is suggested to be the most suitable method for OSL dating of fine grain sediments.

A new image domain STAP method for multi-channel SAR with array distortion and non-homogeneity environments

A new image domain STAP method for multi-channel SAR with array distortion and non-homogeneity environments

Ice Surface Topography Digital Elevation Model by Interferometric SAR Method

Research on the issue of climate change and its influence on ice sheets calls for increasing use of methods based on remote measurements and monitoring. Work on the Devon Island Ice Cap in Canada demonstrated the value of interferometric synthetic aperture radar. Analyses of two image pairs yielded a digital elevation model that could be used for evaluations of ice mass dimensions and characteristics. This method was found to produce metric accuracy with a resolution of 100 m geocoded DEM and with an accuracy of 5.43 m compared to field-derived GPS measurements.

Imaging by Means of an Immobile Antenna Array, Noise Signals and SAR Method

It is developed a new method of SAR imaging through the use of noise/random signals and a fixed and non-switching antenna array as suggested in [1]. The main idea of the method consists in the separation from the total signal of the single-channel receiver of that its portion, which is radiated by a separate element of the array. Such extraction is performed using correlation reception of the noise/random signals transmitted and received by the antenna array with mutual delay between the antenna elements, which is exceeding the correlation time of the transmitted signal. The advantage of the suggested method for SAR imaging consists in the non-necessity of either mechanical moving or electronic switching of the antenna array elements, which simplifies its design and cuts the costs. The SAR imaging algorithm is described and the results of PC modeling of SAR using the proposed antenna array are presented.

Identification of Endocrine Disruptor Biodegradation by Integration of Structure–activity Relationship with Pathway Analysis

We present a SAR method that can predict estrogen-like endocrine disrupting chemical (EDC) activity as well as key biodegradation steps for detoxification. This method is based on a recent graph-mining algorithm developed by Kudo et al., which generates a set of descriptors from all potent chemical fragments (including rings). This method is novel in that it achieves chemical diversity in the training data set by sampling another data set of larger diversity. The model achieved an 83% accuracy prediction rate, and identified 1291 EDC candidates from the KEGG database. From this set of candidate compounds, bisphenol A was chosen for assay validation and biodegradation pathway analysis. Results showed that bisphenol A exhibited estrogen-like activity and was degraded in three distinct reactions. The prediction model provided information on the mechanism of the ligand-target binding, such as key functional groups involved. We focused on the enzyme commission number, which is useful for analyses of biodegradation pathways. Results identified oxygenases, ether hydrolases, and carbon-halide lyases as being important in the biodegradation pathway. This combined approach provided new information regarding the biodegradation of EDCs, and can potentially be extended to applications with transcriptomic, proteomic, and metabolomic data to provide a quick screen of biological activity and biodegradation pathway(s).

Simulation of optically‐stimulated luminescence of zircon

AbstractMineral zircon, ZrSiO4, belongs to a class of materials that can be used as a chronological tool in geology and archaeology for measurements of the natural radiation dose and the sample age by optical methods. The model of optically stimulated luminescence developed earlier is used to investigate the applicability of the single‐aliquot regenerative‐dose method (SAR) for dating with zircon. Various implementations of the SAR method are considered and practical recommendations are formulated. (© 2007 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Advanced DInSAR analysis on mining areas: La Union case study (Murcia, SE Spain)

The town of La Union (SE, Spain) is located within a metal mining area that has been exploited since the Roman period. This historic exploitation has left behind a high concentration of abandoned underground mining galleries. Currently, an industrial area is subsiding due to the collapse of one of these galleries in May 1998. In this paper, an advanced Differential Interferometry SAR (DInSAR) method called the Coherent Pixels Technique (CPT) has been used to study the subsidence phenomena for two time intervals, from January 1998 to December 2000, and from March 2003 to December 2004. DInSAR-derived deformation maps have enabled the detection and monitoring of different deformation processes that affect several locations within the study area. By comparing these results with the underground mining galleries map, a clear relationship between their presence and the subsidence has been proved. Deformation values retrieved with DInSAR between April 2003 and December 2004 have been compared with the topographical leveling network measurements performed in this same period, providing an absolute average difference of 0.7 cm with a standard deviation of 0.5 cm. Results obtained in the city of La Union have shown that the advanced DInSAR technique is able to provide very useful spatial and temporal deformation data for the measurement of small scale subsidence throughout short time periods. This technique has enabled the temporal evolution of the phenomena in the city of La Unión to be studied and understanding of subsidence to be expanded beyond the limits of a deployed topographical control network, in a more cost effective way than classical methods.

The role of the European Chemicals Bureau in promoting the regulatory use of (Q)SAR methods†

Under the proposed REACH (Registration, Evaluation and Authorisation of CHemicals) legislation, (Q)SAR models and grouping methods (chemical categories and read across approaches) are expected to play a significant role in prioritising industrial chemicals for further assessment, and for filling information gaps for the purposes of classification and labelling, risk assessment and the assessment of persistent, bioaccumulative and toxic (PBT) chemicals. The European Chemicals Bureau (ECB), which is part of the European Commission's Joint Research Centre (JRC), has a well-established role in providing independent scientific and technical advice to European policy makers. The ECB also promotes consensus and capacity building on scientific and technical matters among stakeholders in the Member State authorities and industry. To promote the availability and use of (Q)SARs and related estimation methods, the ECB is carrying out a range of activities, including applied research in computational toxicology, the assessment of (Q)SAR models and methods, the development of technical guidance documents and computational tools, and the organisation of training courses. This article provides an overview of ECB activities on computational toxicology, which are intended to promote the development, validation, acceptance and use of (Q)SARs and related estimation methods, both at the European and international levels. †Presented at the 12th International Workshop on Quantitative Structure-Activity Relationships in Environmental Toxicology (QSAR2006), 8–12 May 2006, Lyon, France.

Structure-activity relationships and pathway analysis of biological degradation processes

(Q)SARs estimate biological activity; however these models are insufficient to fully understand and predict the ADME-Tox processes of small molecules in biological systems. By integrating (Q)SARs with biological databases, the predictive capability of these models can be significantly improved. However, the techniques and methods for integrated analysis have not yet been sufficiently developed for these combined systems. In this review, we discuss standard (Q)SAR methods and biological database construction as well as provide an example of how SAR and metabolic pathway analysis can be combined to examine the biological degradation processes of endocrine disrupting chemicals.

G407 炭素系アブレーションを伴う融合衝撃層の多温度解析(2)(GS-4-2 飛翔体,円柱,一般セッション)

Numerical simulation of nonequilibrium shock-layer flows was performed for the reentry conditions of MUSES-C with carbonaceous ablation effects by an extended merged shock-layer theory based on a 4-temperature and 16 chemical species model. The numerical calculations assumed a continuum approach and the system of governing equations constituted a two-point boundary value problem on a stagnation-point streamline, which was solved numerically by the SAR method. The effects of ablation on temperatures and flowfields were discussed in detail. It was found that the ablation from a body surface had significantly influence on various physico-chemical values in the merged shock-layer.

Sar Remote Sensing of Snow Parameters in Norwegian Areas — Current Status and Future Perspective

The paper present results from a series of European and national projects on remote sensing of snow parameters. Currently, satellite borne SAR data are only available at C-band frequencies. Other frequencies such as L-band or Ku-band may be favorable in several snow applications, but current C-band SAR may still be used and further developed to a more mature level. In particular, the advent of wide swath SAR data have provided frequent data sets at medium spatial resolution, that can be used to monitor snow parameters operationally.We will present results from a snow covered area monitoring service developed for Norway and Sweden. The service, which is based on Envisat ASAR wide swath data, produces snow cover maps on average 3–4 times per week. The resulting time series gives a unique data set for studying the snow cover as it rapidly retreats during the melting season, and is of high value to hydro power companies.Snow water equivalent is the key parameter for hydrological applications. Norut IT has developed a technique using repeat pass interferometry to measure SWE, based on the linear relationship between the change in SWE and the change in interferometric phase. The technique has been demonstrated, but scarceness of usable interferometric baseline pairs have so far not allowed wide spread applicability of the technique.A future SAR using Ku-band frequency as carrier will maybe solve the problem of retrieving SWE. Since backscatter at Ku-band frequency is more sensitive to SWE, it is good hope that robust SAR methods can be invented for this purpose. It will, however, be extremely important for the scientific community to validate the retrieval algorithms against in-situ data. The authors have developed an innovative validation concept using ground-penetrating radars at the same carrier frequencies as the space borne SARs to validate EO data in an efficient manner. The concept has been studied at C-band frequencies on glaciers at Svalbard, and we hope to build a similar platform for Ku-band frequencies, which will be used to validate model based retrieval algorithms.