Estimation Of Deformation Research Articles

Thermal Anomaly, Co-Seismic Deformation and Seismic Source Parameters Estimation of June 21 2022, Afghanistan Earthquake Employing InSAR Observations

Thermal Anomaly, Co-Seismic Deformation and Seismic Source Parameters Estimation of June 21 2022, Afghanistan Earthquake Employing InSAR Observations

Geomorphological transformations and future deformation estimations of a large potential landslide in the high-order position area of Diexi, China

Landslides in high-order position areas pose a serious threat to residents located below such areas. Therefore, research on the evolution process and underlying dynamic mechanisms is crucial. The majority of relevant studies are based on landslides that have already occurred; however, the investigation of potential landslides is of higher value. In this study, a progressive potential landslide identification method is proposed with the application of SBAS-InSAR (Small Baseline Subset Interferometric Synthetic Aperture Radar) and subsequently combined with Google Earth, GF-1 (Gaofen-1), GF-2 (Gaofen-2), ZY-3 (Ziyuan-3) and UAV (Unmanned Aerial Vehicle) imagery, and DEM (Digital Elevation Model) for further validation. The proposed method is employed to determine the potential landslide in Tuanjiecun by integrating the multi-period data to simultaneously analyze the evolution and mechanism of the potential landslide. The long short-term memory method is then adopted to predict the evolution trend based on accumulative deformation from SBAS-InSAR. The results suggest that the deformation of Tuanjiecun potential landslide will increase to −238.57 mm. This article provides a new approach for disaster prevention and mitigation by determining a potential landslide using composite remote sensing and predicting the development of the potential landslide on indirect contact monitoring.

Joint Estimation of Ground Displacement and Atmospheric Model Parameters in Ground-Based Radar

Atmospheric delay is the primary error in ground-based synthetic aperture radar (GBSAR). The existing compensation methods include the external meteorological data correction method, the polynomial fitting method, and the persistent scatterers SAR interferometry (PSInSAR) calibration method. Combining the polynomial fitting and the persistent scatterers targets is the most popular method of GBSAR atmospheric delay compensation. However, the displacement component of the coherent target is always ignored in the atmospheric delay compensation, which is unpractical. A joint estimation method of ground displacement and atmospheric model parameters is developed in this paper. The displacement component is determined by the spatial and temporal features of the objects. The atmospheric delay component is regarded as a systematic error represented by a quadratic polynomial related to distance. The result is resolved by the least-square method. Compared to the existing method, the root-mean-square error (RMSE) of the proposed method had a significant improvement in the validation experiment. In the real in situ experiment, the time series obtained by the GBSAR had a similar trend to that acquired by the Global Positioning System (GPS) receiver. It is indicated that the proposed method can lead to a better deformation estimation by taking the deformation component into account in the atmospheric compensation.

Assessment of paperboard large deformation at fold using digital image correlation technique

Abstract For coated paperboard with large deformations, there is limited knowledge on the mechanisms that lead to coating damage and on the key properties that affect damage. Large deformations produce complex non-linear mechanical responses which often result in significant internal damage. The objective of this work was to establish methods to directly measure local deformation at a fold using a stereo digital image correlation (DIC) technique and a folding device designed in-house. This allowed monitoring of deformation from both cross-section and surface views, from which curvature and strain could be analyzed. This approach allowed observation and quantification of the initiation and propagation of damage. Testing showed that elastic estimation of deformation is valid only at very small curvatures but is still qualitatively useful. It was found that CD fold line shows a lower strain than MD fold line at a given curvature, but it ultimately reaches a higher level of surface strain. Additionally, localized maximum surface strain was shown to correlate better with surface damage at fold than the average surface strain. Furthermore, the introduced discontinuity index can provide a useful tool to compare surface damage at fold even for paperboard samples with different thicknesses.

Comparing Several Different Numerical Approaches for Large Deformation Modeling with Application in Soil Dynamic Compaction

Dynamic compaction (DC) is vastly utilized to improve the strength characteristics of the soils. To predict the soil deformations derived from the DC operations, usually numerical simulation analysis is applied. For the conduction of such simulations, several numerical approaches with different elemental formulations can be used. From the perspective of finite element analysis (FEA), there are four main formulations including the Lagrangian, Arbitrary Lagrangian-Eulerian (ALE), Coupled Lagrangian-Eulerian (CEL), and Smoothed Particle Hydrodynamic (SPH). In this research, a comparative study has been conducted to evaluate the computational efficiency of those four approaches in the prediction of soil large deformations during the DC operations. To do this, for a DC operation executed in a road embankment construction project in China, the real field data was compared to the results obtained from the numerical simulations via the ABAQUS program. The findings demonstrate that of all those approaches, the Lagrangian approach delivers the minimum accuracy of the predicted results, albeit with the least running time. In contrast, the ALE formulation predicted closer estimations of soil deformations although it was found to be less time-efficient. Interestingly, the CEL and SPH approaches predicted the soil deformations with the maximum degree of accuracy whereas they were not as time-efficient as the Lagrangian approach. To address this issue, a hybrid model of Lagrangian and SPH formulations was constituted to satisfy the maximum accuracy with the minimum running time. Such a hybrid model is highly applicable for the accurate prediction of soil large deformations during the DC operations.

Realisation of an optical pressure standard by a multi-reflection interferometric technique

A novel realization of an optical pressure standard, alternative to Fabry-Perot cavity-based techniques, is presented. It is based on the measurement of the refractive index of a gas through an unbalanced homodyne interferometer, designed to have one of its two arms formed by a multi reflection double mirror assembly to establish an unbalance length larger than 6 m in a compact setup.The paper illustrates the most important steps concerning its realization: the estimate of the pressure-induced deformation of the interferometer, the temperature control at millikelvin level and the measurement in vacuum of the unbalance of the interferometer.The evaluation of the uncertainty of the realized optical pressure standard currently demonstrated to fulfill the main goal of having the ability to measure pressure with a relative uncertainty of 10 ppm at 100 kPa.

A Simplified Deformation Estimation Method for Anchor Piles of Sheet Pile Quay Walls under Kinematic Forces during Earthquakes

In the seismic design of quay walls, it is necessary to evaluate the deformation of the walls during earthquakes as well as the safety of structural members. However, conventional seismic design methods for sheet pile quay walls cannot accurately determine the degree of deformation. One reason for this is that conventional methods do not consider kinematic forces acting on an anchor pile due to the deformation of the ground. This study proposes a simplified estimation method for anchor pile deformation under the influence of kinematic forces. The results of two-dimensional finite element analysis reveal that anchor pile deformation involves rotational and translational components caused by the kinematic forces, which the conventional methods do not consider. The deformation of the anchor pile caused by kinematic forces was 30%–40% of the total deformation at the pile head. It was clarified that unlike horizontally stratified ground, shear stress is generated in the ground before an earthquake resulting in the kinematic force acting on the anchor pile during the earthquake. Furthermore, a simplified method for estimating the deformation of the anchor pile under kinematic forces that uses one-dimensional seismic response analysis considering the predicted shear stress based on a theoretical equation is proposed. It was demonstrated that the proposed method accurately reproduces the anchor pile deformation.

Numerical Estimation of Shaft Stability and Surface Deformation Induced by Underground Mining Transferred from Open-Pit Mining in Jinfeng Gold Mine

In this study, a three-dimensional finite difference numerical model of the Jinfeng Gold Mine, including surface topography, ore body, shafts, and main faults, was built to estimate the shaft stability and surface deformation induced by underground mining transferred from open-pit mining. Satellite monitoring data of surface displacement at several points was used to calibrate the numerical model. The sequence of excavation and filling in the simulation was determined according to the mining schemes with appropriate simplification. The distribution of large deformations in simulation is consistent with the cracking areas on the slopes and surface. Besides, shaft deformation in the simulation is small, which is consistent with the reality that there are no large deformations of shafts in the underground mining activities above 30 m level. After the completion of simulated underground mining, the deformations of shafts and surface are generally far less than the critical deformation. Hence, we concluded that the shafts and surface of the Jinfeng Gold Mine can remain stable in the underground mining stage. Overall, the method in the study provides references for the estimation of shaft stability and surface deformation in the underground mining stage of mine transfer from open pit.

Large-scale shake table testing of shallow tunnel-ground system

Soil-structure interaction (SSI) is of critical importance in evaluating the seismic response of shallow tunnels. Experimental observations are crucial in assessing the influence of the surrounding and overburden soil near the ground surface. Therefore, this paper presents a series of shake table tests to investigate the seismic response of a scaled shallow tunnel with different backfill material properties and thickness of overburden soil (burial depth). A shallow tunnel was tested incorporating ground representative of realistic backfill conditions using the large-scale 1-g outdoor shake table at the University of California, San Diego (UCSD). The tunnel structure was designed at 1/9 scale based on the configuration of an actual recently constructed prototype structure in San Francisco, California. The test results were interpreted in full-scale, which demonstrated that the maximum tunnel deformation generally occurred at the instant of peak ground acceleration (PGA). Relatively large shear strains were developed (up to 6%) and significant reduction of the soil shear modulus were evaluated as the PGA increased during the shaking. The backfill shear strains were lower as the tunnel embedment depth increased because of the increased soil stiffness and strength due to the higher overburden stress. In addition, the tunnel racking deformation became closer to that of the ground as the tunnel embedment increased. At the largest observed soil shear strains, tunnel racking was significantly lower than that of ground deformation due to the decrease in soil. The FHWA simplified solution was used to estimate tunnel racking deformation and wall bending moments. The FHWA solution produced reasonable estimates of ground deformation. However, a discrepancy was noted in estimating the tunnel deformation in the given ground deformation known as racking ratio (Rr). This discrepancy contributed to conservatism in the FHWA racking prediction that was pronounced particularly with the decreased overburden soil stress.

Analytical prediction of ground movements due to circular shaft construction in clayey soils

With the rapid expansion of urbanization, shafts are needed to provide access to tunnelling projects or be utilized for permanent works. Their construction causes ground movements, affecting nearby foundations and buried infrastructure. This study presents an analytical equivalent volume loss approach for predicting three-dimensional ground movements resulting from a circular shaft construction: namely, ground losses in the elastic isotropic half space as a sequence of cavity contractions around the shaft are employed. First, the applicability and accuracy of proposed solutions are evaluated with published case studies and centrifuge tests. Thereafter, the method is employed to investigate the influence of the circular shaft construction on the surface and subsurface soil displacements. Considering design ground losses, this method allows for quick estimations of ground deformations and associated risk of serviceability losses.

Breast asymmetry classification and diagnostics

Breast asymmetry is a polyetiological condition, which may be caused by congenital characteristics, developmental abnormalities, hormonal changes, traumas or surgery. The estimation of breast symmetry should be performed by the plastic surgeon while planning the augmentation or reduction mammoplasty as well as reconstructive surgery. Breast asymmetry is a widespread condition, according to some reports, it can be found in more than half of women. Anthropometric methods, as well as radiology methods, are used to diagnose and estimate breast asymmetry. There are many classification systems of breast asymmetry. The first ones were based on breast appearance or etiology of asymmetry, while modern classifications combine morphologic and etiologic principles. Today there is no conventional diagnostic protocol for breast asymmetry, where it would be listed, which breast parameters should be measured during breast asymmetry estimation. The first attempts were made in the middle of the XX century. Works of Penn, Smith and Westreich are considered to be basic in this field. Generally, relationships between major breast soft-tissue reference points (nipple, areola, submammary fold, lateral border) and bone structures (breastbone, jugular notch, clavicle) are estimated.Mathematic formulas for counting breast volume depending on its linear measurements were developed as well. Nowadays the importance of skeleto-muscular system state (the presence of scoliosis or rib cage deformation) estimation is emphasized, while these conditions can also cause breast asymmetry.

RETROSPECTIVE STUDY OF VERTICAL GROUND DEFORMATION IN COMO, NORTHERN ITALY: INTEGRATION OF LEVELLING AND PSI MEASUREMENTS

Abstract. Subsidence-related vertical ground deformation due to natural and anthropogenic factors may lead to considerable damages to structures and infrastructures, and may increase the occurrence probability of consequential events, such as floods, especially on sea and lake shores. Como city, placed in the north of Italy, adjacent to Como Lake, is subjected to significant subsidence phenomenon, which has been monitored by geodetic levelling networks. In this work the historical geodetic levelling measurements and satellite-based Synthetic Aperture Radar (SAR) data archive are integrated to assess the accuracy of Atmospheric Delay and Deformation Rate estimations obtained through Persistent Scatter Interferometry (PSI) techniques. Tree levelling measurement datasets acquired in 1990, 1997 and 2004 are used in order to obtain the precise deformation rate at the benchmarks for two periods of 1990–1997 and 1997–2004. For multi-temporal InSAR analysis, 106 SAR images (1992–2004) and 41 SAR images (1992–2004) in Ascending Track orbit from ERS-1/2 missions are used in this study. The assessment is performed through a statistical comparison between two sets of vertical land deformation rates obtained by integrated methods. The results of the validation represented a good consistency between deformation rates derived by both techniques. Also, this study has revealed the potential of SAR images acquired in gyro-less mode by ERS-2 mission (2001–2004) in terms of the estimation of ground deformation.

Seismicity caused by hydrological regime of large reservoirs

By the analysis of the results of assessing the deformations of the base with a change in the hydrological regime of reservoirs, it is stated that during the operation of large reservoirs, its base and coastal slopes are located in the field of compression and tension loads of the corresponding intensity of the base bending amplitudes with a variation in water volume. It is shown that mountain massifs deformations at large reservoirs' bases can correspond to limiting tectonic focal deformations, which directly affect the regular stress-strain state and background geodynamic movements near the lying seismically active layer of the earth's crust. The study aims to identify the conditions for developing local geodynamic processes in the zones of deformational influence of large reservoirs, solving problems of mathematical physics for specific seismically active fault zones crossing the foundations of large hydraulic structures. An analysis of the results of processing the observed earthquake frequency, elastic displacements in the near zones of reservoirs, and estimates of local deformations shows the influence of changes in the hydrological regime in reservoirs on the activation of weak local earthquakes. It is explained that they are non-linear in nature and are associated with other influencing factors: additional load, the presence of local and active tectonic faults, flooding, and changes in pore pressure.

Estimation of large-scale deformations in VLBI radio source catalogs with mitigation of impact of outliers: A comparison between different L1- and L2-norm-based methods

Aims. In this study, we compare several methods of modeling large-scale systematic differences between catalogs of positions of extragalactic radio sources provided by very long baseline interferometry with an emphasis on mitigating the impact of outliers. Methods. The coordinate difference between catalogs was parameterized by first and second order coefficients of vector spherical harmonics. We solved for these coefficients by using the least-squares method (L2-norm) and, alternatively, by L1-norm minimization. The problem of outliers was addressed either by rejecting them on the basis of their difference to the mean or by using the cell median (CM) method, consisting of reducing the difference field to median values in cells of equal area. The methods were applied to simulated catalogs exhibiting systematics of within 100 microarcseconds - for which we knew the expected results - and to real catalogs. Results. In simulations, the L1 minimization appears practically insensitive to outliers and is within a few microarcseconds of the expected results. Least-squared fitting preceded by L1-norm-based outlier detection performed similarly. The CM method gets close to the true parameter values, within one microarcsecond. When applied to real catalogs, all methods provide close results within a few microarcseconds. Conclusions. The study shows that all tested methods are consistent with each other within a few microarcseconds. Hybrid L2/L1 and iterative L2 methods proved to be very effective in eliminating outliers and showed the best accuracy of the estimated parameters of the mutual orientation of celestial reference frames.

ОЦІНКА ВЕРТИКАЛЬНИХ РУСЛОВИХ ДЕФОРМАЦІЙ РІЧОК БАСЕЙНУ ТЕТЕРЕВА

The investigation of vertical channel deformations of the main rivers of the Teteriv basin over the last 40 years according to the data of 6 hydrological stations was carried out. The prerequisite for this was the establishment of trends in changes in the water discharge of the considered watercourses. A general decrease of these indicators, especially the average and maximum flow indicators, was revealed. This is confirmed by previously conducted studies on water level fluctuations of the researched rivers. The results proved a universal increase in water levels for the rivers of the basin at fixed water discharge within the river banks. This is evidence that accumulation processes are observed on all explored riverbeds, although their intensity may be manifested in different ways. It is shown that modern vertical channel deformations characterize the accumulation of sediments in the riverbeds of the basin, the average intensity of which varies within 0.27-1.31 cm/year. In general, this trend is confirmed by the change in the longitudinal profiles of the rivers during the specified period, where in the areas where the hydrological stations are located, a slight shift of one relative to the other can be observed, with the prevailing height positions of the longitudinal profile for the year 2020. Comparative analysis of discrete (according to flow curves based on data from hydrological stations) and continuous (according to longitudinal profiles) estimates of vertical channel deformations makes it possible to more objectively establish the trends of their manifestations.

A new hyperelastic lookup table for RT-DC.

Real-time deformability cytometry (RT-DC) is an established method that quantifies features like size, shape, and stiffness for whole cell populations on a single-cell level in real-time. A lookup table (LUT) disentangles the experimentally derived steady-state cell deformation and the projected area to extract the cell stiffness in the form of the Young's modulus. So far, two lookup tables exist but are limited to simple linear material models and cylindrical channel geometries. Here, we present two new lookup tables for RT-DC based on a neo-Hookean hyperelastic material numerically derived by simulations based on the finite element method in square and cylindrical channel geometries. At the same time, we quantify the influence of the shear-thinning behavior of the surrounding medium on the stationary deformation of cells in RT-DC and discuss the applicability and impact of the proposed LUTs regarding past and future RT-DC data analysis. Additionally, we provide insights about the cell strain and stresses, as well as the influence resulting from the rotational symmetric assumption on the cell deformation and volume estimation. The new lookup tables and the numerical cell shapes are made freely available.

Model-Aware Pre-Training for Radial Distortion Rectification.

Camera lenses often suffer from optical aberrations, causing radial distortion in the captured images. In those images, there exists a clear and general physical distortion model. However, in existing solutions, such rich geometric prior is under-utilized, and the formulation of an effective prediction target is under-explored. To this end, we introduce Radial Distortion TRansformer (RDTR), a new framework for radial distortion rectification. Our RDTR includes a model-aware pre-training stage for distortion feature extraction and a deformation estimation stage for distortion rectification. Technically, on the one hand, we formulate the general radial distortion (i.e., barrel distortion and pincushion distortion) in camera-captured images with a shared geometric distortion model and perform a unified model-aware pre-training for its learning. With the pre-training, the network is capable of encoding the specific distortion pattern of a radially distorted image. After that, we transfer the learned representations to the learning of distortion rectification. On the other hand, we introduce a new prediction target called backward warping flow for rectifying images with any resolution while avoiding image defects. Extensive experiments are conducted on our synthetic dataset, and the results demonstrate that our method achieves state-of-the-art performance while operating in real-time. Besides, we also validate the generalization of RDTR on real-world images. Our source code and the proposed dataset are publicly available at https://github.com/wwd-ustc/RDTR.

Evaluation of recursive Bayesian filters for modal contribution estimation in high-tech compliant mechanisms

This study evaluates three recursive Bayesian input and state estimation algorithms, as introduced in the field of Structural Health Monitoring, for estimating modal contributions for high-tech compliant mechanisms. The aim of estimating modal contributions is the use for active vibration control. High-tech compliant motion stages allow for different sensor configurations, making new and interesting performance evaluations of these filters possible. The algorithms used, namely, the Augmented Kalman Filter (AKF), Dual Kalman Filter (DKF) and Gilijns de Moor Filter (GDF) are implemented on a compliant motion stage for guidance flexure deformation estimation. Our results show the GDF performs overall best, with good estimation performance and real-world tuning capability.

Toward Accurate and Efficient Road Extraction by Leveraging the Characteristics of Road Shapes

Automatically extracting roads from very high resolution (VHR) remote sensing images is of great importance in a wide range of remote sensing applications. However, complex shapes of roads ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i.e</i> ., long, geometrically deformed, and thin) always affected the extraction accuracy, which is one of the challenges of road extraction. Based on the insight into road shape characteristics, we propose a novel road shape aware network (RSANet) to achieve efficient and accurate road extraction. First, we introduce the Efficient Strip Transformer Module (ESTM) to efficiently capture the global context to model the long-distance dependence required by the long roads. Second, we design a Geometric Deformation Estimation Module (GDEM) to adaptively extract the context from the shape deformation caused by shooting roads from different perspectives. Third, we provide a simple but effective Road Edge Focal Loss (REF loss) to make the network focus on optimizing the pixels around the road to alleviate the unbalanced distribution of foreground and background pixels caused by the roads being too thin. Finally, we conduct extensive evaluations on public datasets to verify the effectiveness of RSANet and each of the proposed components. Experiments validate that our RSANet outperforms state-of-the-art methods for road extraction in remote sensing images.

Robust Surface Deformation and Tropospheric Noise Characterization From Common-Reference Interferogram Subsets

Interferometric Synthetic Aperture Radar (InSAR) surface deformation estimates often suffer from tropospheric noise errors, and many study sites do not have GPS or in-situ measurements for validating InSAR surface deformation solutions. Here we present a method for characterizing both surface deformation and tropospheric noise from interferogram subsets. Choosing different subsets of interferograms that use a common-reference SAR scene allows us to quantify tropospheric noise and deformation signals. We demonstrate this method using 95 C-Band Sentinel-1 SAR scenes acquired over the Oman Ophiolite and 133 scenes over the Island of Hawaii. For the Oman case, our method suggests that there is no detectable deformation signal. In this scenario, the average of any subset of interferograms with a common-reference SAR scene estimates the tropospheric noise contribution on that reference SAR date. Achieving ~0.5 cm of uncertainty requires a subset size of 40 common-reference interferograms. The observed tropospheric noise is non-Gaussian, and follows a seasonal pattern. Propagation of tropospheric noise leads to up to ~5 cm of false deformation signal when deriving either a stacking or SBAS time series solution. For the Hawaii case, our method shows that the observed InSAR phase on the south flank of Kilauea is due to a secular deformation signal, while the phase over Mauna Loa is mostly associated with tropospheric noise. Our results are validated with independent GPS tropospheric zenith delay and surface deformation time series with sub-cm RMS errors.