Estimation Of Deformation Research Articles

Reliability of inelastic wind excited structures by dynamic shakedown and adaptive fast nonlinear analysis (AFNA)

The ever-growing interest in performance-based wind engineering has created a need for assessment frameworks that can efficiently deal with inelasticity. The computationally efficient strain-driven dynamic shakedown approach has provided a solution that is not only capable of identifying failure mechanisms that are potentially critical during extreme winds, e.g., low cycle fatigue and ratcheting, but also allows direct estimation of inelastic deformations. This approach, however, can only solve problems at dynamic shakedown, i.e., with limited nonlinearity, and is not capable of providing response time histories. To address these limitations, this paper presents an efficient framework for reliability assessment of inelastic structures at dynamic shakedown and beyond. To this end, a novel step-by-step integration algorithm is developed for rapid response time history analysis within the setting of dynamic shakedown. The method is based on advancing fast nonlinear analysis through introducing schemes for enabling at each time step the adaptive selection of the step size, number of modes to be included, and number of potentially nonlinear elements. Inelasticity is modeled as distributed at the level of the stress resultants through a return mapping scheme based on the Haar–Kàrmàn principle, therefore enabling the integrated estimation of the state of dynamic shakedown. The scheme is seen to preserve the efficiency of recently developed strain-driven dynamic shakedown algorithms while providing a full range of response time histories at and beyond the state of dynamic shakedown. To enable reliability analysis, the scheme is embedded in a general uncertainty propagation framework.

A real-time spatial deformation estimation method based on spatial curvature decomposition and interpolation

Structural deformation entails safety risks, and at times, direct measurement can be challenging, especially when reference points are unavailable. Therefore, the development of a practical and precise deformation estimation method is crucial. This paper introduces a strain-based method with spatial curvature decomposition and interpolation for estimating structural deformation. The proposed method was tested through numerical simulations of various static and dynamic deformation cases for different structures, including a railway track, a rigid hanger of a bridge under low-frequency dynamic loads, and a cantilever beam under high-frequency dynamic loads. The feasibility of the method was verified, and it was further validated by a field test on a railway track. Compared to existing strain-based methods, it offers more flexible sensor placement, requires fewer parameters, and can estimate dynamic, static, planar, and spatial deformations. This strain-based method shows promise for real-time structural deformation monitoring, enhancing safety assessments.

Biomechanical characterization of tissue types in murine dissecting aneurysms based on histology and 4D ultrasound-derived strain

Abdominal aortic aneurysm disease is the local enlargement of the aorta, typically in the infrarenal section, causing up to 200,000 deaths/year. In vivo information to characterize the individual elastic properties of the aneurysm wall in terms of rupture risk is lacking. We used a method that combines 4D ultrasound and direct deformation estimation to compute in vivo 3D Green-Lagrange strain in murine angiotensin II-induced dissecting aortic aneurysms, a commonly used mouse model. After euthanasia, histological staining of cross-sectional sections along the aorta was performed in areas where in vivo strains had previously been measured. The histological sections were segmented into intact and fragmented elastin, thrombus with and without red blood cells, and outer vessel wall including the adventitia. Meshes were then created from the individual contours based on the histological segmentations. The isolated contours of the outer wall and lumen from both imaging modalities were registered individually using a coherent point drift algorithm. 2D finite element models were generated from the meshes, and the displacements from the registration were used as displacement boundaries of the lumen and wall contours. Based on the resulting deformed contours, the strains recorded were grouped according to segmented tissue regions. Strains were highest in areas containing intact elastin without thrombus attachment. Strains in areas with intact elastin and thrombus attachment, as well as areas with disrupted elastin, were significantly lower. Strains in thrombus regions with red blood cells were significantly higher compared to thrombus regions without. We then compared this analysis to statistical distribution indices and found that the results of each aligned, elucidating the relationship between vessel strain and structural changes. This work demonstrates the possibility of advancing in vivo assessments to a microstructural level ultimately improving patient outcomes.

Establishment of Localized Utilization Parameters for Numerical Simulation Analysis Applied to Deep Excavations

The aim of this study was to apply deep excavation behavior prediction models in the geotechnical field to establish localized soil parameters for gravel layers. Common software tools, including PLAXIS and SoilWorks, were used extensively. Monitoring data from deep excavation cases related to gravel layers in the Xindian area of Taiwan were collected. In the background analysis, the deformation of the retaining walls was used instead of parameters typically used in deep excavation analysis. This was performed to provide the ideal range recommendations for the input parameters when conducting a numerical simulation analysis of the Xindian District stratum or similar strata. The assessment results show that when setting the fifth layer of gravel to SPT-N = 100, PLAXIS suggested a soil elastic modulus range of 7840 N to 9800 N per square meter (kN/m2), while SoilWorks recommended a range of 2450 N to 3430 N per square meter (kN/m2). These ranges allow for a reasonable estimation of the maximum wall deformation during the final excavation stage. Based on the research findings, it is recommended that when conducting an excavation analysis in gravel layers in the Xindian area of Taiwan or in similar strata, engineers should refer to the abovementioned recommended ranges when selecting the soil elastic modulus for different software programs. This will enhance the accuracy of the deformation predictions during the final excavation stage.

Effects of 3D deformation and nonlinear stress–strain relationship on the Brazilian test for a transversely isotropic rock

To improve the accuracy of indirect tensile strength for a transversely isotropic rock in the Brazilian test, this study considered the three-dimensional (3D) deformation and the nonlinear stress–strain relationship. A parametric study of a numerical Brazilian test was performed for a general range of elastic constants, revealing that the 3D modeling evaluated the indirect tensile strength up to 40% higher than the plane stress modeling. For the actual Asan gneiss, the 3D model evaluated the indirect tensile strength up to 10% higher and slightly enhanced the accuracy of deformation estimation compared with the plane stress model. The nonlinearity in stress–strain curve of Asan gneiss under uniaxial compression was then considered, such that the evaluated indirect tensile strength was affected by up to 10% and its anisotropy agreed well with the physical intuition. The estimation of deformation was significantly enhanced. The further validation on the nonlinear model is expected as future research.

Relating in-vivo Strain of the Flexor Digitorum Superficialis Tendon with Grip Force

Epidemiological studies have shown a relationship between hand exertion and risk of developing distal upper extremity musculoskeletal disorders (DUEMSDs). Recently, fatigue-failure models were proposed for estimating the risk of DUEMSD development. However, models that incorporate tendon strain are primarily based on in-vitro data and may be better informed using in-vivo data. This methodological pilot study aimed to establish an approach for correlating grip force and spatiotemporal strains of the flexor digitorum superficialis (FDS) tendon using ultrasound imaging. Three image texture correlation techniques to measure in-vivo strains were explored and compared: digital image correlation, direct deformation estimation, and StrainNet, a novel deep learning neural network for strain prediction. StrainNet resulted in more accurate strain measurements than conventional image assessment tools, enabled continuous prediction of FDS tendon strain, and allowed for comparison of median bulk tissue strain during isometric contraction to grip force. Future work will study more participants and viscoelastic behavior.

Abstract P1096: Computational Motion Artifact Removal Acts As Virtual Blebbistatin In Ipsc-derived Cardiomyocytes And Micro-tissues

Introduction: Drugs like blebbistatin that paralyze tissues are critical for accurate optocardiography but directly affect sarcomeres, making it challenging to study structure-function relationships. To overcome this, we applied Direct Deformation Estimation (DDE), a robust strain estimation tool, to enable computational motion removal from videos of beating monolayers and engineered heart tissues formed from human Induced Pluripotent Stem Cell derived cardiomyocytes (hiPSC-CM). Methods: hiPSC-CM and miniaturized engineered heart muscles were stained with the far-red voltage sensitive dye, BeRST-1. Videos of overall motion (bright-field), Ca 2+ (endogenous GCamP6f reporter) and voltage were captured at 100 Hz. Temporal median filtering and Contrast-Limited Adaptive Histogram Equalization were applied as pre-processing steps to improve convergence. The inverse of conformal mappings estimated from DDE were used to “unwarp” videos to artificially reduce motion. Removal of motion was assessed in bright-field videos by performing optical flow analysis. Improvements in optical mapping accuracy were estimated by calculating the spatial distribution of APD 80 (voltage) and time to 75% decay from peak (τ 75 ; Ca 2+ ). Results: Virtual blebbistatin removed >90% of motion from monolayers and engineered tissues without affecting sarcomere architecture (sarcomeric α-Actinin staining), in contrast to chemical blebbistatin. Virtual blebbistatin further reduced spatial dispersion in both APD 80 and τ 75, leading to overall distributions that were less skewed by artificially low repolarization times. Interestingly, when directly assessing Ca 2+ -contraction coupling in plots of motion-corrected Ca 2+ vs. contraction magnitude, we observed that engineered tissues had more uniform and consistent coupling compared to monolayers. Conclusions: Superior uniformity in calcium-contraction coupling of engineered tissues as opposed to monolayers is consistent with observations that engineered tissues are more likely to recapitulate genotype-phenotype relationships and drug responsiveness. Virtual blebbistatin is a promising tool for non-invasive analysis of Ca 2+ -contraction coupling and robust optocardiography.

SequenceMorph: A Unified Unsupervised Learning Framework for Motion Tracking on Cardiac Image Sequences.

Modern medical imaging techniques, such as ultrasound (US) and cardiac magnetic resonance (MR) imaging, have enabled the evaluation of myocardial deformation directly from an image sequence. While many traditional cardiac motion tracking methods have been developed for the automated estimation of the myocardial wall deformation, they are not widely used in clinical diagnosis, due to their lack of accuracy and efficiency. In this paper, we propose a novel deep learning-based fully unsupervised method, SequenceMorph, for in vivo motion tracking in cardiac image sequences. In our method, we introduce the concept of motion decomposition and recomposition. We first estimate the inter-frame (INF) motion field between any two consecutive frames, by a bi-directional generative diffeomorphic registration neural network. Using this result, we then estimate the Lagrangian motion field between the reference frame and any other frame, through a differentiable composition layer. Our framework can be extended to incorporate another registration network, to further reduce the accumulated errors introduced in the INF motion tracking step, and to refine the Lagrangian motion estimation. By utilizing temporal information to perform reasonable estimations of spatio-temporal motion fields, this novel method provides a useful solution for image sequence motion tracking. Our method has been applied to US (echocardiographic) and cardiac MR (untagged and tagged cine) image sequences; the results show that SequenceMorph is significantly superior to conventional motion tracking methods, in terms of the cardiac motion tracking accuracy and inference efficiency.

Prediction of bubble shape deformation in aqueous solutions of short-chain alcohols

The behaviour of bubbles in aqueous solutions of short-chain alcohols depends significantly on the alcohol concentration. At low concentrations, alcohols act as surfactants and slow the rising velocity of the bubble, whereas at higher concentrations, primarily due to the internal arrangement at the molecular level, the desorption of molecules from the bubble surface is facilitated and the mobility of the bubble surface is increased. These factors significantly affect both bubble velocity and deformation. On the basis of experimental data (aqueous solutions of ethanol and propanol in the entire concentration range), two relations were proposed for the estimation of bubble deformation depending on the dimensionless Weber number. The model was successfully verified on an independent data set of the velocity and deformation of bubbles that rise in a stationary liquid.

Analysis of the fault slip, creep, and coupling characteristics of the Maomaoshan-Laohushan-Haiyuan Fault using InSAR and GNSS measurements

Line-of-sight Interferometric Synthetic Aperture Radar (InSAR) observations are affected by long-wavelength errors and the inaccurate estimation of vertical deformation, thereby restricting horizontal slip rate estimations for strike-slip faults, such as the Maomaoshan-Laohushan-Haiyuan Fault (MMS-LHS-HY). To overcome this limitation, herein, InSAR (2016–2022) and Global Navigation Satellite System (GNSS) observations were combined and the Least Squares Variance Component Estimation (LS-VCE) method was used to obtain the Three-Dimensional (3-D) deformation field of the Haiyuan fault zone; subsequently, the slip-rate and coupling distributions were inverted. The results showed that: (1) Compared with the GNSS and leveling deformation velocities, the residuals of the 3-D deformation field obtained using the LS-VCE method combined with the GNSS and InSAR observations reached an RMS of 1 mm/a, significantly better than the deformation field obtained without GNSS data. (2) Vertical deformation from InSAR observations led to over- or under-estimation of the fault strike-slip rate, with the maximum influence on the shallow creep rate of 2.1 mm/a. (3) Based on the 3-D deformation field, fault slip rate, locking depth, and fault creep characteristics obtained from the elastic dislocation and elastic block models were consistent with each other. (4) The strike-slip rate of the MMS-LHS-HY fault gradually decreased from west to east, whereas the thrust rate gradually increased in the same direction. (5) Based on the 3-D deformation field, the creep range of the LHS fault was ∼40 km, with the mean shallow creep rate reaching 2.5 ± 0.1 mm/a, notably larger than the creep rate obtained by ascending InSAR observation alone.

Correlation of Ground Deformation Induced by the 6 February 2023 M7.8 and M7.5 Earthquakes in Turkey Inferred by Sentinel-2 and Critical Exposure in Gaziantep and Kahramanmaraş Cities

On 6 February 2023, an M7.8 devastating earthquake started rupturing the East Anatolian fault system in Turkey, resulting in intense shaking that lasted over a minute. A second earthquake of magnitude 7.5 struck near the city of Elbistan a few hours later. Both of these events are associated with the East Anatolian fault system. The earthquake sequence caused widespread damage and collapse of structures in densely populated areas throughout the Southern Turkey and Northern Syria regions and a very large number of human losses. This study focuses on the correlation of the ground deformation with the critical exposure of the infrastructures of Gaziantep and Kahramanmaraş cities. The estimation of the ground deformation of the affected area is achieved with the use of Copernicus Sentinel-2 products and the Normalized Cross Correlation algorithm (NCC) of image matching. The results of the East–West component show that specific sections of the region moved towards the East direction, reaching displacement measurements of 5.4 m, while other sections moved towards the West direction, reaching displacement measurements of 2.8 m. The results of the North–South component show that almost the whole affected area moved towards the North direction, with specific areas reaching displacements of 5.5 m, and a few exemptions, as some areas moved towards the South direction, with displacements reaching even 6.9 m. Regarding the cities of Kahramanmaraş and Gaziantep, their estimated movement direction is North-West and North-East, respectively, and is consistent with the movements of the Arabian and Anatolian Plates in which they are located. Important infrastructures of the study areas (education, museums, libraries, hospitals, monuments, airports, roads and railways) are superimposed on the findings, enabling us to detect the critical exposure rapidly.

Full-Coverage Path Planning and Stable Interaction Control for Automated Robotic Breast Ultrasound Scanning

Ultrasound examination is widely used for diagnosis of breast cancer, which requires a full-coverage scan of the whole organ and stable probe–breast interaction for high-quality image acquisition. In this study, a robotic system for automated breast ultrasound scanning is proposed. To avoid occlusion, point cloud of the breast is obtained from multiple angles and registered together for accurate tissue shape reconstruction, then scan path planning is performed with isometric 3-D point cloud searching algorithm for full and uniform coverage. To reduce the adverse influence of large tissue deformation during ultrasound scanning, a contact force–strain regression model is built for tissue deformation estimation and used as a feedforward to correct the planned scanning path, and a probe–tissue interaction model with scanning resistance is built for normal probe orientation adjustment. To maintain normal probe orientation and stable contact force during robotic ultrasound scanning, a hybrid force–velocity control framework is proposed based on admittance control algorithm. Experiment results show that the robotic system can successfully maintain a constant contact force and keep the probe's posture along the normal orientation of probe–breast interaction both in in-plane direction and out-of-plane direction.

Study of anisotropic compact stars by exploring tidal deformability

In this paper, the effect of anisotropy on the tidal deformability of a compact neutron star is investigated. In particular, it is possible to quantify the tidal Love number, which is defined by tidal deformability. Tidal Love number provides the estimation of the tidal deformability of the binary system in response to the external gravitational field. The effect of anisotropy and compactness factor on the tidal Love number has been examined for a specific class of solutions that describes an anisotropic compact object.

Recent estimates of the ground deformation from remote sensing and terrestrial data around the High Dam Area, Aswan, Egypt

The Aswan High Dam, located in southern Egypt, is considered one of the most strategic engineering structures in Egypt. After its full operation of the dam in 1971, a series of micro-earthquakes occurred around the High Dam. The largest seismic event recorded in the region was in November 14, 1981, earthquake with a magnitude of 5.6 ML, located 60 km to the southwest of the dam. Due to the great importance of this area, a combination of remote sensing (InSAR) and terrestrial data (precise leveling) was used to shed light on the current state of crustal deformation in this area. The data collected from three leveling lines (six campaigns) covering the period 2013–2022 in addition to 107 SAR scenes (2017–2021) from the Sentinel-1 mission were used to estimate the up-to-date ground deformation of the study area. The results from both Small Baseline Subset (SBAS) and leveling measurements show that the fault normal velocity of the Spillway fault is approximately 3 ± 0.15 mm/yr. The obtained results coincide with the seismicity pattern recorded in the study area, as the seismic events close to the dam are characterized by normal fault mechanisms. Outcomes show the importance of combining terrestrial (leveling) and space geodetic techniques (InSAR) to map the active faults and estimate the deformation rates along these faults.

High-resolution monitoring of landslides with UAS photogrammetry and digital image correlation

ABSTRACT Periodically monitoring landslides is a key factor for supporting the realisation of hazard warning systems and risk reduction in the corresponding neighbourhood areas. Although satellite remote sensing solutions can be considered for low spatial resolution monitoring, this approach is still inappropriate for high spatial resolution investigations. Ground-based Radar Interferometry is also a widely used technique that allows for working at a proper spatial resolution, but it can often be an overbudget solution for most applications. Instead, photogrammetric surveys based on Unmanned Aerial System (UAS) imagery appear as a very interesting approach in terms of both spatial resolution and flexibility in temporally repeating the survey. Motivated by this observation, this work investigates the use of multi-temporal UAS surveys for landslide monitoring. To be more precise, Digital Image Correlation (DIC) has been applied to orthomosaics generated from different UAS photogrammetry surveys to compute the area’s deformation map. Compared with a reference GNSS survey, the results obtained using NHAZCA IRIS software and an in-house DIC approach show a deformation estimation accuracy of approximately 0.1 m, a reasonable accuracy for landslides moving at moderate velocity.

On the seafloor horizontal displacement from cGPS and compass data in the Campi Flegrei caldera

Seafloor deformation monitoring is now routinely performed in the marine sector of the Campi Flegrei volcanic area (Southern Italy). The MEDUSA infrastructure is formed by four buoys deployed at a water depth ranging from 40 to 96 m, and equipped with cGPS receivers, accelerometers and magnetic compasses to monitor the buoy status and a seafloor module with a bottom pressure recorder and other onboard instruments. The analysis of the time series data acquired by the MEDUSA monitoring infrastructure system allows to study the seafloor deformation in the Campi Flegrei caldera with geodetic accuracy. In a previous work, we show that the time series acquired by the Campi Flegrei cGPS onland network and MEDUSA over the period 2017–2020 are in good agreement with the ground deformation field predicted by a Mogi model which is widely used to describe the observed deformation of an active volcano in terms of magma intrusion. Only for one of the buoys, CFBA (A), the data differ significantly from the model prediction, at a level of simeq 6.9 sigma and of simeq 23.7 sigma for the seafloor horizontal speed and direction, respectively. For this reason, we devised a new method to reconstruct the horizontal sea bottom displacement considering in the analysis both cGPS and compass data. The method, applied to the CFBA buoy measurements and validated also on the CFBC (C) buoy, uses compass data to correct cGPS positions accounting for the pole inclination. Including also systematic errors, the internal consistency, always within sim 3 sigma for the speed and sim 2 sigma for the angle, between the results derived for different maximum inclinations of the buoy pole (up to 3.5^{circ }) indicates that the method allows to significantly reduce the impact of the pole inclination which, if not properly taken into account, can alter the estimation of the horizontal seafloor deformation. In particular, we find a good convergence of the retrieved velocity and deformation angle as we include in the analysis data from increasing values of the buoy pole inclination. Taking the result derived assuming the maximum allowed cutoff and accounting for statistical and systematic errors, we found a speed v = (3.521 ± 0.039 (stat) ± 0.352 (syst)) cm/yr and a deformation direction angle alpha = (-115.159 ± 0.670 (stat) ± 7.630 (syst))^{circ } (statistical errors at 1 sigma quoted from the rms of their values, main systematic errors added linearly). The relative impact of the main potential systematic (statistical) effects increases (decreases) with the cutoff. Our analysis provides a horizontal speed consistent with the model at a level of simeq 5.2 sigma (stat only) or of simeq 0.5 sigma (stat and syst added linearly), and a deformation angle consistent with the model at simeq 4.3 sigma level (stat only) or at simeq 0.3 sigma level (stat and syst added linearly). Correspondingly, the module of the vectorial difference between the velocity retrieved from the data and the velocity of the adopted Mogi model diminishes by a factor of simeq 7.65 ± 1.23 (stat) or ± 5.78 (stat + syst) with respect to the previous work. A list of potential improvements to be implemented in the system and instruments is also discussed.

A thermal deformation estimation method for high precision machine tool spindles based on the convolutional neural network

A thermal deformation estimation method for high precision machine tool spindles based on the convolutional neural network

CAUSES OF DAMAGE TO PROCESS PIPELINES OF DELAYED COKING UNITS AND MEASURES TO PREVENT THEM

The article provides a calculated justification for the occurrence of damage to process pipelines of delayed coking plants based on checking the strength conditions. Using the software package of finite element analysis ANSYS, based on estimates of temperature deformations of pipelines and coke drums, the calculation of the stress-strain state of pipeline elements is carried out. The results of computational studies indicate the types and locations of damage and show the possibility of preventing damage due to local strengthening of elements of pipelines with an increase in wall thickness. Based on the results obtained, reconstruction measures are proposed in order to prevent damage.

Data-driven estimations of ground deformations induced by tunneling: a Bayesian perspective

Data-driven estimations of ground deformations induced by tunneling: a Bayesian perspective

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