Strip Map Research Articles

Interferometric Calibration Model for the LuTan-1 Mission: Enhancing Digital Elevation Model Accuracy

The LuTan-1 (LT-1) mission, China’s first civilian bistatic spaceborne Synthetic Aperture Radar (SAR) mission, comprises two L-band SAR satellites. These satellites operate in bistatic InSAR strip map mode, maintaining a formation flight with an adjustable baseline to generate global digital elevation models (DEMs) with high accuracy and spatial resolution. This research introduces a dedicated interferometric calibration model for LT-1, tackling the unique challenges of the bistatic system, such as interferometric parameter coupling and the π-ambiguity problem caused by synchronization phase errors. This study validates the model using SAR images from LT-1 and Xinjiang corner reflector data, achieving interferometric phase accuracy better than 0.1 rad and baseline accuracy better than 2 mm, thereby producing high-precision DEMs with a height accuracy meeting the 5 m requirement.

Optimization of Effective Working Hours for Coal Transportation from Rom to Port: Study at Pt. Maruwai Coal Central Kalimantan

Adaro Mineral Indonesia is one of the pillars of Adaro's mining business which focuses on coking coal mining in Central Kalimantan, planning to increase its coal production. The aim of this research is to optimize effective working hours for transporting coal from ROM to the port. This is done to increase the low productivity of coal transportation activities from mines to ports, which will bring benefits in the form of increased operational efficiency. This research was conducted quantitatively. The data used is primary data and secondary data. Primary data in this research was obtained from direct observations in the coal transportation area from the ROM of coal products to port, which includes cycle time, rain duration, shift changes, road conditions. The research method was carried out quantitatively. Optimization of coal transportation can be improved by improving delay parameters, improving communication between transportation operators, carrying out real time communication and data validation, expanding the Change Shift Area, fulfilling man power, making strip maps and road worthiness tests, making work plans, as well as procurement of gravel material and hauling road maintenance as well as All Weather Road conditions.

Prediction of Site Index and Age Using Time Series of TanDEM-X Phase Heights

Site index and stand age are important variables in forestry. Site index describes the growing potential at a given location, expressed as the height that trees can attain at a given age under favorable growing conditions. It is traditionally used to classify forests in terms of future timber yield potential. Stand age is used for the planning of management activities such as thinning and harvest. SI has previously been predicted using remote sensing, but usually relying on either very short time series or repeated ALS acquisitions. In this study, site index and forest stand age were predicted from time series of interferometric TanDEM-X data spanning seven growth seasons in a hemi-boreal forest in Remningstorp, a test site located in southern Sweden. The goal of the study was to see how satellite-based radar time series could be used to estimate site index and stand age. Compared to previous studies, we used a longer time series and applied a penetration depth correction to the phase heights, thereby avoiding the need for calibration using ancillary field or ALS data. The time series consisted of 30 TanDEM-X strip map scenes acquired between 2011 and 2018. Established height development curves were fitted to the time series of TanDEM-X-based top heights. This enabled simultaneous estimation of both age and site index on 91 field plots with a 10 m radius. The RMSE of predicted SI and age were 6.9 m and 38 years for untreated plots when both SI and age were predicted. When predicting SI and the age was known, the RMSE of the predicted SI was 4.0 m. No significant prediction bias was observed for untreated plots, while underestimation of SI and overestimation of age increased with the intensity of treatment.

Subglacial lake activity beneath the ablation zone of the Greenland Ice Sheet

Abstract. Hydrologically active subglacial lakes can drain large volumes of water and sediment along subglacial pathways, affecting the motion and mass balance of ice masses and impacting downstream sediment dynamics. To date, only eight active lakes have been reported beneath the Greenland Ice Sheet (GrIS), and thus the understanding of their spatial distribution and dynamic processes is still lacking. Here, using ICESat-2 (Ice, Cloud, and land Elevation Satellite-2) ATL11 data, we identify 18 active subglacial lakes, 16 of which have not been previously reported. Multi-temporal ArcticDEM (digital elevation model of the Arctic) strip maps were used to extend the time series to verify lakes and determine their drainage history. The identification of active subglacial lakes beneath the GrIS is complicated by the occurrence of supraglacial lakes, which also fill and drain and are hypothesized to be almost co-located. We therefore used the temporal pattern of ice-surface elevation change to discriminate subglacial lakes and utilized the ability of ICESat-2 to penetrate through surface water to correct the elevation provided by the ATL11 data. A significant localized elevation anomaly (−16.03–10.30 m yr−1) was measured in all detected subglacial lakes after correction, revealing that six subglacial lakes are twinned with supraglacial lakes. The active subglacial lakes have large upstream hydrological catchments and are located near or below the equilibrium line. Lakes have a median area of 1.20 km2, and 12 lakes exhibited positive elevation-change rates during the ICESat-2 period. These observations illustrate the potential for combining ICESat-2 and the ArcticDEM to differentiate small subglacial lakes in the ablation zone and beneath supraglacial lakes.

Analysis of Wave Breaking on Gaofen-3 and TerraSAR-X SAR Image and Its Effect on Wave Retrieval

The main purpose of our work is to investigate the performance of wave breaking and its effect on wave retrieval in data acquired from the Chinese Gaofen-3 (GF-3) synthetic aperture radar (SAR) at C-band and the German TerraSAR-X (TS-X) at X-band. The SAR images available for this study included 140 GF-3 images acquired in quad-polarization strip (QPS) mode and 50 dual-polarized (vertical-vertical (VV) and horizontal-horizontal (HH)) TS-X images acquired in stripmap (SM) mode. Moreover, these images were collocated with the waves simulated by the numeric WAVEWATCH-III (WW3) (version 5.16) model and HYbrid Coordinate Ocean Model (HYCOM) current. In particular, a few images covered the moored buoys monitored by the National Data Buoy Center (NDBC) of the National Oceanic and Atmospheric Administration (NOAA). The comparison between the WW3-simulated results and the significant wave heights (SWHs) from the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data (ERA-5) showed that the correlation coefficient (COR) was 0.4–0.6 with a root mean squared error (RMSE) of about 0.2 m at SWHs of 0–4 m. The winds were inverted using VV-polarized geophysical model functions (GMFs), e.g., CSARMOD-GF for the GF-3 images and XMOD2 for the TS-X images. The Bragg resonant roughness in the normalized radar cross section (NRCS) was simulated using a radar backscattering model and the SAR-derived wind, WW3-simulated wave parameters, and HYCOM current. Then, the contribution of the non-polarized (NP) wave breaking to the SAR data was estimated by the VV-polarized NRCS, the HH-polarized NRCS, and the polarization ratio (PR) of the co-polarized Bragg resonant components in the NRCS. Because co-polarized Bragg resonant components in the NRCSs have poor results, due to the saturation for wind speeds greater than 20 m/s, the analysis of wave breaking is excluded at such conditions. The results revealed that the backscattering signal in the C-band was more sensitive to wave breaking than the backscattering signal in the X-band. Interestingly, the ratio had a linear correlation with wind speed. Moreover, the variation in the bias (inverted SWH minus WW3 simulation) showed that the bias increased as the wind speed (>8 m/s) and whitecap coverage (>0.005) increased. Following this rationale, wave retrieval during tropical cyclones should consider the influence of wave breaking.

Combinations of Right Half-Plane Mappings and Vertical Strip Mappings Convex in the Vertical Direction

Combinations of Right Half-Plane Mappings and Vertical Strip Mappings Convex in the Vertical Direction

Spatio-Temporal Anomaly Detection for Substrate Strip Bin Map in Semiconductor Assembly Process

With the development of deep learning, data-driven approaches have shown great success in the semiconductor manufacturing. For example, wafer bin maps (WBM) recognition is a critical application to identify failure modes and finding root-cause to reduce yield loss. However, the WBM studies provide static classification results without tracing the temporal patterns. This study develops a spatio-temporal strip map prediction system for the flip-chip bonding process in the assembly house. The proposed strip bin map (SBM) prognostic system including prediction model and recognition model can provide pre-alarm of defect and predict the defect mode for the final process. In practice, not all processes are followed by a functional test (FT) and thus this proposed system can simulate the defect generation based on the Bayes' theorem for tracking the changes of the spatio-temporal patterns. An empirical study of the semiconductor assembly manufacturer in Taiwan was conducted to validate the proposed framework, and the results show that the proposed SBM system successfully predict the SBM and defect mode for the final test and provide an effective pre-alarm.

Multiparametric sea state fields from synthetic aperture radar for maritime situational awareness

This paper introduces a method for estimating a series of sea state parameters from satellite-borne synthetic aperture radar (SAR). The method was realized in a near real time (NRT) application which allows for the processing of data from different satellites and modes. The algorithm estimates the total significant wave height Hs, dominant and secondary swell and windsea wave heights, first, and second moment wave periods, the mean wave period and the period of wind sea. The algorithm was applied to the Sentinel-1 (S1) C-band Interferometric Wide Swath Mode (IW), Extra Wide (EW) and Wave Mode (WV) Level-1 (L1) products and also extended to X-band TerraSAR-X (TS-X) StripMap (SM) products. The scenes are processed in raster and result in continuous sea state fields, with the exception of S1 WV, where averaged values for sea state parameters for along-orbit imagettes of 20 km × 20 km are presented.The developed empirical algorithm consists of two parts: a first CWAVE_EX (extended CWAVE) part, based on a linear regression approach, and a subsequent machine learning part using the support vector machine (SVM) technique. A series of new data preparation steps (i.e. filtering, denoising) and new features estimated from SAR images are also introduced. The algorithm was tuned and validated using two independent global wave model hindcasts, WaveWatch-3 and MFWAM as well as National Data Buoy Center (NDBC) measurements. The achieved root mean squared errors (RMSE) for CWAVE_EX for the total Hs are 0.60 m for low-resolution modes S1 IW (10 m pixel) and EW (40 m pixel) and 0.35 m for S1 WV and TS-X SM (pixel spacing ca.1–4 m) in comparison to model predictions. The RMSEs of the retrieved wave periods are in the range of 0.45–0.90 s for all of the satellites and models considered. Similarly, the dominant and secondary swell, and wind sea wave height RMSEs are in the range of 0.35–0.80 m. The SVM postprocessing improves the accuracy of the initial results of CWAVE_EX for Hs and reaches an RMSE of 0.25 m for S1 WV. Comparisons to 64 NDBC buoys, collocated at distances shorter than 50 km to S1 WV imagettes worldwide, result in an RMSE of 0.41 m. All results and the methods presented are novel in terms of the accuracy achieved, combining the classical approach with machine learning techniques, and performing an automatic NRT processing of multiparametric sea state fields from L1 data with automatic switching for different satellites and modes.The complete archive of S1 WV L1 Single Look Complex products from December 2014 until February 2021 was processed to create a sea state parameter database and validated using model hindcast and buoy measurements. The derived parameters are available to the public within the scope of the European Space Agency's Climate Change Initiative.

Rotations and convolutions of harmonic convex mappings

In this paper, we mainly consider the convolutions of slanted half-plane mappings and strip mappings of the unit disk D. If f1 is a slanted half-plane mapping and f2 is a slanted half-plane mapping or a strip mapping, then we prove that f1 * f2 is convex in some direction if f1 * f2 is locally univalent in D. We also obtain two sufficient conditions for f1 * f2 to be locally univalent in D. Our results extend many of the recent results in this direction. Moreover, we consider a class of harmonic mappings including slanted half-plane mappings and strip mappings, and as a consequence, we prove that the any convex combination of such locally univalent and sense-preserving mappings is also convex.

Variable-Resolution SAR Imaging Mode With the Principle of Maximum Mutual Information

A generalized synthetic aperture radar (SAR) modality of operation named variable-resolution (VR) SAR is proposed, which explores the diversity of antenna patterns and inhomogeneity of pulse repetition frequencies (PRFs) for adaptive imaging. Based on the relationship between the azimuth resolution and the corresponding integration angle, it uses dynamic beam patterns along the trajectory to illuminate different regions. We formulate the optimization problem of VR SAR based on the principle of maximum mutual information. First, the information content of a specific scene is defined by modeling its distributed scattering as a stochastic process, and the mutual information between scenes and the observed SAR image can be derived. Then, we construct an optimization problem to maximize the mutual information by solving for the optimal beam manipulation scheme of the VR SAR mode. Further optimization of PRF is conducted to obtain a relatively larger swath width and smaller data volume by compromising the resolution of some regions with less information while ensuring there are no azimuth ambiguities. The potential advantages of VR mode are: 1) it simultaneously provides higher resolution for the high-information regions and a larger imaging area than would otherwise be possible in strip map and spotlight SAR modes and 2) it optimizes the efficiency of data acquisition while extracts as much information from scenes as possible. A mathematical model of VR SAR mode with the principle of maximum mutual information is established, and the feasibility and merits of the method are demonstrated through a series of simulations and an equivalent experiment using RADARSAT-1 raw data.

Innovative and Robust Application of Automation for Unit Level Traceability on Dual Die configuration of Micro Electromechanical System Products

Strip mapping for unit level traceability on die attach process of semiconductor companies provide quality driven impression for end users on the market. On processing of Micro electromechanical system packages, strip map generated by operators manually, certain errors and discrepancies are encountered and inevitably experienced by the production line. This causes misleading analysis on manufacturing problems and may lead to inappropriate and incorrect solutions hurting the process line. The application of modern technology and internet of things have been considered as an improvement. This is to eliminate human intervention errors caused by manual practice and promoted fool proof design of procedures. Having a user-friendly application with integration of modern technology drives significant improvement provide benefits to both supplier and customer of the manufacturing world.

Convolutions of Harmonic Mappings Convex in the Horizontal Direction

In this paper, we establish some results concerning the convolutions of harmonic mappings convex in the horizontal direction with harmonic vertical strip mappings. Furthermore, we provide examples illustrated graphically with the help of Maple to illuminate the results.

A proof of a conjecture on convolution of harmonic mappings and some related problems

UDC 517.5 Recently, Kumar et al. proposed a conjecture concerning the convolution of a generalized right half-plane mapping with a vertical strip mapping. They have verified the above conjecture for and . Also, it has been proved only for . In this paper, by using of a new method, we settle this conjecture in the affirmative for all and . Moreover, we will use this method to prove some results on convolution of harmonic mappings. This new method simplifies calculations and shortens the proof of results remarkably.

Kajian Kebutuhan Sarana Perlintasan Warga Desa Liang Dan Neath Pada Sungai Nalbessy Kabupaten Buru Selatan

Maraknya pemberitaan media sosial berjudul “75 Tahun Merdeka Tapi Katong Belum Merdeka” ditampilkan kegiatan warga pedalaman Buru Selatan sebagai pengguna sarana perlintasan menyeberangi sungai Nalbessy. Keselamatan Pengguna sarana dipertaruhkan karena beresiko putus, dan dapat berakibat fatal bila hanyut terbawa derasnya arus sungai. Maraknya pemberitaan media kemudian penulis mengkaji kebutuhan sarana perlintasan bagi warga pedalaman Buru Selatan untuk melintasi sungai Nalbessy. Kajian bertujuan: Menelusuri lokasi dimana kegiatan warga melintasi Sungai Nalbessy, dan mengalisis potensi pengguna sarana perlintasan berdasarkan data kependudukan. Menyajikan history jalan dan jembatan di sekitar Desa Liang dan Neath dalam bentuk stripmap penanganan ruas Namrole – Leksula. Metode penelusuran menggunakan aplikasi Google Earth, tahapan kajian terstruktur dan sistematis sesuai kaidah ilmiah bersumber dari data sekunder. Hasil kajian disimpulkan: Lokasi perlintasan Sungai Nalbessy terletak -3,7628º LS dan 126,5444º BT di Kec. Leksula, Kab. Buru Selatan Provinsi Maluku. Lokasi dimana oleh Dinas PUPR Provinsi Maluku telah direncanakan pembangunan jembatan Wai Nalbessy III. Ruas Namrole–Leksula melintasi 2 desa permukiman warga pedalaman Buru Selatan (Liang dan Neath). Penanganan jalan hingga tahun 2019, kondisi perkerasan masih belum seragam terdiri atas 3 jenis perkerasan: Hotmix 7.0 Km, Timbunan Pilihan 4.0 Km, dan Jalan Tanah 42.0 Km. Penanganan ruas jalan provinsi telah dibangun 3 jembatan dari rencana 33 jembatan. Perkiraan biaya pembangunan, waktu pelaksanaan jembatan bentang 50 meter Wai Nalbessy III, menurut jenis konstruksi, masing-masing: Rp. 4 M, 4 bulan untuk Jembatan gantung pejalan kaki simetris, Rp. 15 M, 10 bulan untuk Rangka Baja, dan Rp. 20 M, 1 Tahun untuk Jembatan beton/GTI.

In-Depth Verification of Sentinel-1 and TerraSAR-X Geolocation Accuracy Using the Australian Corner Reflector Array

This article shows how the array of corner reflectors (CRs) in Queensland, Australia, together with highly accurate geodetic synthetic aperture radar (SAR) techniques-also called imaging geodesy-can be used to measure the absolute and relative geometric fidelity of SAR missions. We describe, in detail, the end-to-end methodology and apply it to TerraSAR-X Stripmap (SM) and ScanSAR (SC) data and to Sentinel-1 interferometric wide swath (IW) data. Geometric distortions within images that are caused by commonly used SAR processor approximations are explained, and we show how to correct them during postprocessing. Our results, supported by the analysis of 140 images across the different SAR modes and using the 40 reflectors of the array, confirm our methodology and achieve the limits predicted by theory for both Sentinel-1 and TerraSAR-X. After our corrections, the Sentinel-1 residual errors are 6 cm in range and 26 cm in azimuth, including all error sources. The findings are confirmed by the mutual independent processing carried out at University of Zurich (UZH) and German Aerospace Center (DLR). This represents an improvement of the geolocation accuracy by approximately a factor of four in range and a factor of two in azimuth compared with the standard Sentinel-1 products. The TerraSAR-X results are even better. The achieved geolocation accuracy now approaches that of the global navigation satellite system (GNSS)-based survey of the CRs positions, which highlights the potential of the end-to-end SAR methodology for imaging geodesy.

On convex combinations of harmonic mappings

Let psi_{mu,nu}(z)=(1-2cosnu e^{imu}z+e^{2imu}z^{2})^{-1}, mu,nuin[0,2pi) and p be an analytic mapping with operatorname{Re} p>0 on the open unit disk. We consider the sense-preserving planar harmonic mappings f=h+overline{g}, which are shears of the mapping int_{0}^{z} psi_{mu,nu}(xi) p(xi),{d}xi in the direction μ. These mappings include the harmonic right half-plan mappings, vertical strip mappings, and their rotations. For various choices of dilatations g'/h' of f, sufficient conditions are found for the convex combinations of these mappings to be univalent and convex in the direction μ.

Developmental Designs and Adult Functions of Cortical Maps in Multiple Modalities: Perception, Attention, Navigation, Numbers, Streaming, Speech, and Cognition.

This article unifies neural modeling results that illustrate several basic design principles and mechanisms that are used by advanced brains to develop cortical maps with multiple psychological functions. One principle concerns how brains use a strip map that simultaneously enables one feature to be represented throughout its extent, as well as an ordered array of another feature at different positions of the strip. Strip maps include circuits to represent ocular dominance and orientation columns, place-value numbers, auditory streams, speaker-normalized speech, and cognitive working memories that can code repeated items. A second principle concerns how feature detectors for multiple functions develop in topographic maps, including maps for optic flow navigation, reinforcement learning, motion perception, and category learning at multiple organizational levels. A third principle concerns how brains exploit a spatial gradient of cells that respond at an ordered sequence of different rates. Such a rate gradient is found along the dorsoventral axis of the entorhinal cortex, whose lateral branch controls the development of time cells, and whose medial branch controls the development of grid cells. Populations of time cells can be used to learn how to adaptively time behaviors for which a time interval of hundreds of milliseconds, or several seconds, must be bridged, as occurs during trace conditioning. Populations of grid cells can be used to learn hippocampal place cells that represent the large spaces in which animals navigate. A fourth principle concerns how and why all neocortical circuits are organized into layers, and how functionally distinct columns develop in these circuits to enable map development. A final principle concerns the role of Adaptive Resonance Theory top-down matching and attentional circuits in the dynamic stabilization of early development and adult learning. Cortical maps are modeled in visual, auditory, temporal, parietal, prefrontal, entorhinal, and hippocampal cortices.

Interferometric Phase Retrieval for Multimode InSAR via Sparse Recovery

Modern spaceborne synthetic aperture radar (SAR) features a capacity of multiple imaging modes. It comes with Earth-observation data archives consisting of SAR images acquired in various modes with different resolutions and coverage. In this context, in addition to using single-mode images for SAR interferometry (InSAR), exploiting images acquired in different imaging modes for InSAR can provide extra interferograms and, thus, favors the retrieval of interferometric information. The interferometric processing of multimode image pairs requires special considerations due to significant variations in the Doppler spectra. Conventionally, the InSAR technique only uses the spectral band common in both master and slave images, and the remaining band is discarded before interferogram formation. Therefore, conventional processing cannot make full use of the observed data, and the interferogram quality is limited by the common band spectra. In this article, by exploiting the conventionally discarded spectrum, we present a new interferometric phase retrieval method for multimode InSAR data to improve interferogram quality. To this end, first, we propose a linear model to characterize the interferometric phase of a multimode image pair based on image spectral relation. Second, we adopt a sparse recovery method to inverse the linear model for the retrieval of the interferometric phase. Finally, we present real-data experiments on TerraSAR-X staring spotlight to sliding spotlight interferometry and Sentinel-1 strip map to Terrain Observation by Progressive Scan (TOPS) interferometry to test the proposed method. The experiment results show that the proposed method can provide interferograms with reduced phase noise and defocusing effect for multimode InSAR.

Squint-looking differential synthetic aperture ladar: signal processing and experimental demonstration.

Squint-looking differential synthetic aperture ladar (DSAL) is reported with detailed signal processing mathematics and high-resolution experimental demonstrations. Based on the DSAL principle and standard squint-looking synthetic aperture radar theory, the data processing procedures on squint-looking DSAL image formation are obtained. The experimental DSAL setup, operating in "step-stop" strip map mode, adopts a frequency chirped laser with a wavelength of 1550 nm as the illuminating source and a specially designed random phase generator to introduce large common mode random phase error (RPE) into the phase history data of both receiving sub-apertures. High-resolution DSAL images of a cooperative target at a distance of 1.85 m and squint-looking angle of $-{10}^\circ$-10∘ or $+{10}^\circ$+10∘ are demonstrated. The DSAL images, with or without large RPE, are all well focused by straightforwardly following the given data processing steps. The result illustrates that the DSAL technique is robust in removing common mode phase errors in squint-looking configuration.

Seasonal cycles of lakes on the Tibetan Plateau detected by Sentinel-1 SAR data

The long-term evolution of lakes on the Tibetan Plateau (TP) could be observed from Landsat series of satellite data since the 1970s. However, the seasonal cycles of lakes on the TP have received little attention due to high cloud contamination of the commonly-used optical images. In this study, for the first time, the seasonal cycle of lakes on the TP was detected using Sentinel-1 Synthetic Aperture Radar (SAR) data with a high repeat cycle. A total of approximately 6000 Level-1 scenes were obtained that covered all large lakes (>50 km2) in the study area. The images were extracted from stripmap (SM) and interferometric wide swath (IW) modes that had a pixel spacing of 40 m in the range and azimuth directions. The lake boundaries extracted from Sentinel-1 data using the algorithm developed in this study were in good agreement with in-situ measurements of lake shoreline, lake outlines delineated from the corresponding Landsat images in 2015 and lake levels for Qinghai Lake. Upon analysis, it was found that the seasonal cycles of lakes exhibited drastically different patterns across the TP. For example, large size lakes (>100 km2) reached their peaks in August–September while lakes with areas of 50–100 km2 reached their peaks in early June–July. The peaks of seasonal cycles for endorheic lakes were more pronounced than those for exorheic lakes with flat peaks, and glacier-fed lakes with additional supplies of water exhibited delayed peaks in their seasonal cycles relative to those of non-glacier-fed lakes. Large-scale atmospheric circulation systems, such as the westerlies, Indian summer monsoon, transition in between, and East Asian summer monsoon, were also found to affect the seasonal cycles of lakes. The results of this study suggest that Sentinel-1 SAR data are a powerful tool that can be used to fill gaps in intra-annual lake observations.