Deformation Tracking Research Articles

Track Deflection Monitoring for Railway Construction Based on Dynamic Brillouin Optical Time-Domain Reflectometry.

Real-time online monitoring of track deformation during railway construction is crucial for ensuring the safe operation of trains. However, existing monitoring technologies struggle to effectively monitor both static and dynamic events, often resulting in high false alarm rates. This paper presents a monitoring technology for track deformation during railway construction based on dynamic Brillouin optical time-domain reflectometry (Dy-BOTDR), which effectively meets requirements in the monitoring of both static and dynamic events of track deformation. Dy-BOTDR can provide a two-dimensional spatial-temporal distribution map of track strain changes to characterize various events for better monitoring accuracy and lower false alarm rates.

Field evaluation of a novel thermally controlled subgrade for mitigating frost heave

ABSTRACT A new type of thermally controlled subgrade is proposed to mitigate persistent frost heave issues of railway subgrades in seasonally frozen regions. A dedicated ground-source heat pump system collects low-grade geothermal energy from the stable soil layer near the subgrade, converts it into high-grade thermal energy, and transfers it to the frigid subgrade for active heating and temperature control, thereby eliminating the adverse effects of frost heave. A 20-metre-long test section of thermally controlled subgrade was constructed in a frost heave section of the Junggar-Shenchi Railway in Shanxi Province, China. During the winter spanning 2021 and 2022, the heating temperature of the heat pump, the thermal regime of the test section subgrade and the natural subgrade, the frost depth, and the track heave were measured. The results indicate that the heat pump temperature could reach a peak of 59.4 °C, with the average daily heating temperature during intermittent operation reaching 25.2 °C or higher, indicating an efficient heat source that plays a favourable role. The freezing period of the natural subgrade lasted for 141 days, while the subgrade in the test section was 20 days shorter. The maximum frost depths at the track centre, shoulder, and embankment slope toe in the test section were 88 cm, 75 cm, and 58 cm, respectively. These depths were 60 cm, 122 cm, and 78 cm less than those of the natural subgrade, effectively controlling the frost depth within the threshold that may cause potential structural damage. Under natural conditions, the track heave reached a peak of 9.4 mm, leading to a harmful frost heave scenario. In contrast, the track deformation in the test section was less than 3 mm, which did not exceed the regular maintenance threshold. The thermally controlled subgrade proves to be an effective method for preventing and controlling persistent frost heave damage in critical locations such as low embankments, cut section subgrades, turnout areas, and culvert roofs.

The Practicality of Quality Assessment Metrics for Millimetre‐Scale Digital Image Correlation Speckle Patterns

ABSTRACTDigital image correlation (DIC), often used in multidisciplinary applications by nonexperts, relies heavily on the quality of a speckle pattern for accurate deformation tracking. Numerous metrics have been developed to assess speckle pattern quality and guide decision‐making in DIC postprocessing. This investigation considered the applicability of these metrics in the selection of an optimal speckling method for two‐dimensional DIC strain measurements, using the standard Brazilian tensile strength rock mechanics laboratory test as a case study. Four speckle patterning methods—spray paint, airbrush, stamp and laser engraving—were optimized to produce patterns of good visual quality for this specific DIC setup. Twenty specimens, five for each method, were prepared, and their speckle patterns were analysed using 10 published metrics. Each pattern was also deformed numerically to quantify the associated systematic and random errors. Overall, none of the 10 metrics demonstrated substantial agreement with the numerical experiment errors due to their failure to account for the confounding influence of pattern characteristics. Consequently, these tools are limited in their usefulness to evaluate the accuracy and reproducibility of speckle patterns with similar characteristics. Numerical simulation of pattern deformation is recommended as the most accurate resource for nonexpert DIC users to assess reproducibility and select optimal patterning methods in practical applications.

The solar radiation induced spatiotemporal temperature distribution and time-varying temperature effect in long-span ballastless track continuous beam-arch bridge

The influence of a time-varying temperature environment on the mechanical performance and geometric alignment of long-span ballastless track continuous beam-arch bridge is significant. However, the structural temperature loads are often simplified into a single mode, making it difficult to accurately simulate the evolution of geometric alignment of long-span ballastless track continuous beam-arch bridge under time-varying temperature effects. To explore the spatiotemporal distribution characteristics of temperature fields and the evolution patterns of track geometric alignment in long-span ballastless track continuous beam-arch bridge, a refined analysis model for the time-varying temperature field is established incorporating ray tracing methods and real-time shadow techniques. Combining the temperature experiment results, the spatiotemporal distribution characteristic and evolution patterns of temperature across the bridge system and key sections are explored. Building on this foundation, the evolution of track geometric alignment on the bridge is analyzed, and the measures for controlling track geometric alignment are proposed. The research findings indicate that the surface temperature of the structure undergoes periodic changes throughout the day, and the orientation of the bridge significantly influences the temperature field of the beam-track structure. The vertical displacement extremes of the ballastless track on the bridge are positively correlated with the structural temperature. The track maintenance moments affect the track alignment on the bridge, but the extreme deformation of the ballastless track and the temporal variation pattern of the structural system temperature remain consistent. To minimize irregularities in the ballastless track geometric alignment on the bridge, adjustments to the track position during high-speed railway maintenance window should choose the moments close to the daily average temperature, aiming to decrease the effects of time-varying temperature on track irregularity.

Video-based Soft Tissue Deformation Tracking for Laparoscopic Augmented Reality-based Navigation in Kidney Surgery.

Minimally invasive surgery (MIS) remains technically demanding due to the difficulty of tracking hidden critical structures within the moving anatomy of the patient. In this study, we propose a soft tissue deformation tracking augmented reality (AR) navigation pipeline for laparoscopic surgery of the kidneys. The proposed navigation pipeline addresses two main sub-problems: the initial registration and deformation tracking. Our method utilizes preoperative MR or CT data and binocular laparoscopes without any additional interventional hardware. The initial registration is resolved through a probabilistic rigid registration algorithm and elastic compensation based on dense point cloud reconstruction. For deformation tracking, the sparse feature point displacement vector field continuously provides temporal boundary conditions for the biomechanical model. To enhance the accuracy of the displacement vector field, a novel feature points selection strategy based on deep learning is proposed. Moreover, an ex-vivo experimental method for internal structures error assessment is presented. The ex-vivo experiments indicate an external surface reprojection error of 4.07 ± 2.17mm and a maximum mean absolutely error for internal structures of 2.98mm. In-vivo experiments indicate mean absolutely error of 3.28 ± 0.40mm and 1.90±0.24mm, respectively. The combined qualitative and quantitative findings indicated the potential of our AR-assisted navigation system in improving the clinical application of laparoscopic kidney surgery.

Influence of large-diameter shield tunneling on deformation of adjacent high-speed railway subgrade in soft soils and effectiveness of protective measures

The excavation of large-diameter shield tunnels in soft soils inevitably impacts adjacent high-speed railway infrastructure. This study investigates the effects of constructing a 14.02 m large-diameter shield tunnel on the deformation of a nearby high-speed railway subgrade in soft soils of Shanghai, and evaluates the effectiveness of various protective measures. A numerical model was developed to simulate the horizontal deformations of railway subgrade piles, as well as the vertical and horizontal deformations of track slab resulting from shield excavation. Comprehensive real-time monitoring of track slab displacements in both vertical and horizontal directions, along with ground surface deformation, was conducted. The accuracy of the computational model and the effectiveness of the implemented protective measures were validated through field measurements. The results demonstrate that isolation piles with coupling beams proved to be the most effective method for protecting the railway subgrade. The maximum observed ground settlement above the tunnel reached −20.3 mm, while the peak heave was recorded at 3.7 mm. Notably, the additional vertical and horizontal deformations of the high-speed railway track were successfully constrained within the 2-mm threshold. These findings provide valuable insights for safety assessments and the implementation of protective measures in similar projects.

Laser-induced nano-Ag/graphene composites for highly responsive flexible strain sensors

In this focused on laser-induced nano-Ag/graphene composites were evaluated as an electrode layer for highly responsive flexible strain sensors. The dimension of Ag nanoparticles was adjusted using potassium hydroxide (KOH) at different concentrations. Moreover, the characteristics of laser-induced nano-Ag/graphene composites were examined by scanning electron microscope, X-ray photoelectron spectroscopy, and X-ray diffraction. The performance of the proposed sensor was tested using a single-column universal test equipment combined with a precision electrical meter. The 6 M KOH nano-Ag/graphene-based strain sensor had large gauge factors of 23.1 under a micro-strain of 0.0042 % and 492.95 under a 16 % strain. Furthermore, the strain sensor under 10 cycles of stretching/releasing demonstrated excellent linearity, repeatability, and stability of response in different strain ranges of 1 % to 13 % at 2 % intervals. The sensor under 3 % and 5 % strain for 1000 cycles of stretching/releasing tests exhibited good stability and durability. The proposed sensor used to detect wind turbine blade deformation exhibited better response performance. The developed sensor holds a great application potential in real-time monitoring of the structural health of bridges and deformation of railway tracks, tracking human movement, identifying hill slides, assessing fatigue of mechanical components, etc.

Cherenkov Imaged Bio-morphological Features Verify Patient Positioning with Deformable Tissue Translocation in Breast Radiotherapy

PurposeAccurate patient positioning is crucial for precise radiotherapy dose delivery, as errors in positioning can profoundly influence treatment outcomes. This study introduces a novel application for loco-regional tissue deformation tracking via Cherenkov image analysis, during fractionated breast cancer radiotherapy. The primary objective of this research was to develop and test an algorithmic method for Cherenkov-based position accuracy quantification, particularly for loco-regional deformations which do not have an ideal method for quantification during radiotherapy. Methods and materialsBio-morphological features in the Cherenkov images such as vessels were segmented. A rigid/non-rigid combined registration technique was employed to pinpoint both inter- and intra-fractional positioning variations. The methodology was tested on an anthropomorphic chest phantom experiment via shifting treatment couch with known distances and inducing respiratory motion, to simulate inter-fraction setup uncertainties and intra-fraction motions respectively. It was then applied to a dataset of fractionated whole breast radiotherapy human imaging (n=10 patients). ResultsThe methodology provides quantified positioning variations, comprising two components: a global shift determined through rigid registration, and a two-dimensional variation map illustrating loco-regional tissue deformation quantified via non-rigid registration. Controlled phantom testing yielded an average accuracy of 0.83 mm for couch translations up to 20 mm in various directions. Analysis of clinical Cherenkov imaging data from ten breast cancer patients compared to their first imaged fraction revealed an inter-fraction setup variation of 3.7 ± 2.4 mm in the global shift and loco-regional deformation up to 3.3 ± 1.9 mm (95th percentile of all regional deformation). ConclusionsThis study introduces the use of Cherenkov visualized bio-morphological features to quantify the global and local variations in patient positioning based on rigid and non-rigid registrations. This new approach demonstrates the feasibility to provide quantitative guidance for inter-/intra-fraction positioning, particularly for the loco-regional deformations that have been unappreciated in current practice with conventional imaging techniques.

Prognostic value of cardiac magnetic resonance global circumferential strain assessed by feature tracking techniques in asymptomatic patients with significant aortic regurgitation

Abstract Introduction Cardiac magnetic resonance feature tracking (CMR-FT) deformation techniques have gained significant interest in recent years. They provide a comprehensive evaluation of myocardial function and improve the reproducibility of echocardiography strain techniques. Purpose The aim of this study was to evaluate whether CMR-FT deformation parameters play a role predicting worse clinical evolution in patients with chronic significant aortic regurgitation (AR) not meeting guidelines intervention criteria. Methods We included 85 patients with significant AR (moderate, moderate/severe, and severe) referred for CMR. Only asymptomatic patients with preserved left ventricle ejection fraction (LVEF) were considered for inclusion. Other concomitant myocardiopathies were excluded. Conventional functional left chambers parameters as well as myocardial deformation were evaluated, including global longitudinal strain (GLS), global circumferential strain (GCS) and global radial strain (GRS). A composite clinical major outcome was assessed, including admission heart failure admission, need for aortic valvule replacement and all-cause mortality. Results The mean age of the sample was 62 years old. One third of the patients were females. Other clinical baseline characteristics were not significantly different between groups when compared with Chi-squared and T-test statistical analysis. Mean follow-up was 42 months (±31). 21 patients presented with the composited outcome previously described. End-diastolic and end-systolic volumes did not differ between groups. Mean end-diastolic volume (EDV) was 196 ± 6.1 mL and mean end-systolic volume (ESV) was 88 ± 3.4 mL. Mean values of CMR-FT GLS, GCS and GRS were -14.1%, 22.8% and -16.9% respectively. GCS was selected as the best predictor for the combined endpoint point, with and area under the ROC curve of 0.67. A GCS value <-17% was selected as the optimal cut-off point. This value predicted events as is shown in Kaplan-Meier curves (HR 3.6, CI 95% 1.42 - 9.02, p = 0.007). A multivariate analysis showed that this association was independent of left ventricle (LV) ejection fraction, LV volumes and left atrial (LA) volume. Conclusion CMR-FT deformation parameters are impaired in significant AR patients even if intervention criteria are not met. A value of GCS < -17% in this population could predict a worse clinical evolution and emerges as a promising new tool helping clinical decision making in this challenging population.Kaplan-Meier curve free-event survival

A review on the deformation tracking methods in vision-based tactile sensing technology

A review on the deformation tracking methods in vision-based tactile sensing technology

Deformation tracking of honeycomb structure based on image skeletonization and branch point matching

Honeycomb structures have attracted much attention in various engineering fields due to its superiorities in high specific strength, high specific stiffness and excellent energy-absorbing characteristics. Therefore, it is very important to obtain the deformation state of honeycomb structure in the studies of its manufacturing process and mechanical behavior. In this study, a simple and efficient strategy for tracking the deformation of thin-walled honeycomb structure based on image skeletonization and branch points matching is presented. Principle and process of the new proposed strategy are first detailed, including image skeletonization, branch points selection, matching expansion and deformation calculation, etc. Simulations and experiments with compression and tensile deformations are performed to verify the efficiency of the proposed strategy. The results indicate that the displacement measurements based on the proposed strategy are able to provide subpixel-level accuracy, even though some interference branch points are generated during deformation. In addition, the limitations of the proposed strategy are discussed, which points out the train of thought for the subsequent research.

Enhancement of Microwave Heating Technology for Emulsified Asphalt Mixtures Using SiC-Fe3O4 Composite Material.

The application of microwave heating technology can significantly enhance the water evaporation rate of emulsified asphalt mixtures post paving. To improve the microwave absorption and curing performance of these mixtures, SiC-Fe3O4 composite material (SF) was incorporated. This addition aims to enhance the microwave absorption efficiency and accelerate the curing process of emulsified asphalt mixtures under microwave heating. This study begins with an analysis of the microwave absorption principles pertinent to emulsified asphalt mixtures. Subsequently, the microwave heating temperature fields of ordinary emulsified asphalt mixture (EAM), SiC emulsified asphalt mixture (S-EAM), Fe3O4 emulsified asphalt mixture (F-EAM), and SiC-Fe3O4 emulsified asphalt mixture (SF-EAM) were simulated using COMSOL Multiphysics finite element software (COMSOL 6.2). The early strength variations in SF-EAM under different microwave heating durations were then examined through adhesion tests, leading to the proposal of a microwave heat curing process for SF-EAM. Finally, the wear resistance, water damage resistance, rutting resistance, and skid resistance of SF-EAM post-microwave curing were evaluated through wet wheel wear tests, wheel track deformation tests, and road friction coefficient tests. The results indicate that the optimal microwave heating time is 90 s, with the microwave absorption performance of the materials ranked as follows: EAM, S-EAM, F-EAM, and SF-EAM, from lowest to highest. The road performance of SF-EAM complies with specification requirements, and its wear resistance, water damage resistance, and rutting resistance are notably improved after microwave heating.

Effect of Tunnel Floor Heave on the Deformation and Damage Behavior of Ballastless Track Structures in High-Speed Railways

The extensive development of high-speed railways in mountainous areas has underscored the significant challenge posed by tunnel floor heave, affecting the operational reliability of ballastless tracks. Such heave induces track deformation and structural impairments, critically undermining the operational safety and track serviceability. This investigation enhances the understanding of ballastless tracks’ mechanical responses to tunnel floor heave by introducing a sophisticated nonlinear analytical model that encapsulates the interplay between the track system, tunnel infrastructure, and the encasing geological environment. Utilizing the concrete damaged plasticity approach to model the track’s concrete structure, this research integrates these parameters with the track’s numerical representation, taking into account the role of internal reinforcement. Through an in-depth examination of track deformation, the interstitial gap, and damage progression within the track, it is demonstrated that comprehensive consideration of both the material’s constitutive model and reinforcement structuring is imperative. The analysis results indicate that the heave’s amplitude and wavelength exert limited influence on the deformation amplitude ratio, whereas variations in heave characteristics significantly alter the wavelength transmission ratio, engendering a distinct “M” shaped gap profile. It is observed that the propensity for material damage escalates in areas experiencing pronounced tensile stress, particularly under conditions of reduced wavelength and increased amplitude heave, necessitating prioritized attention in track maintenance protocols.

Modeling test study on influence mechanism of large-span double-arch tunnels in proximity to existing tracks

This paper aims to study the influence mechanism of the large-span double-arch tunnels in proximity to existing tracks using 1 g model test. A novel non-contact device able to measure settlements automatically is developed to improve the test accuracy. During the test, the strata settlement, surrounding rock stress and track deformation induced by tunnel excavation are measured simultaneously. The results show that: (1) The excavation of the double-arch tunnel induces an asymmetric “W”-shaped horizontal surface settlement. The horizontal surface settlement near the centerline of the first excavation side is the largest. (2) The U-shaped groove structure exhibits an “M”-shaped deformation, while its structure produces bulges near the maximum horizontal surface settlement. (3) After excavation, the longitudinal surface settlement gradually decreases along the excavation direction, which causes the tilting or bottom voids of the U-shaped groove structure. The U-shaped groove structure may experience torsional shear damage under the load imposed by the train.

Numerical Modeling of a Low-Cobalt All-Solid-State Cell with Ceramic Electrolyte Using a Deformable Geometry

All-solid-state batteries with a lithium negative electrode and a ceramic electrolyte are key toward high energy density. To ensure a safe, fast, accurate, and cost-effective development of this technology, the experimental methodology must be supported by the numerical modeling approach. This work proposes and describes an electrochemical model of a Li7La3Zr2O12 (LLZO) and Ni-rich NMC-based lithium cell with a deformable lithium negative electrode. Simulations were computed using the finite element method at different operating conditions to demonstrate the scope of the modeling work. Discharge rate tests, deformation tracking, geometric defect investigation, and polarization decomposition are described. Theoretical validation of the mass balance, the stripping rate, the ohmic polarization, and the mesh deformation demonstrated the consistency of the volumetric deformation strategy. We demonstrated in this study a deformable modeling strategy, which was found to be useful for the electrostripping analysis of anodic geometry defects during discharge. Non-uniformity in the lithium stripping rate was found along the anodic interface with defects, and this non-uniformity was accentuated with a higher discharge rate. The cell’s discharge potential was decomposed by considering the equilibrium potential and the polarizations of the main components of the cell. This post-processing was found to be useful for the understanding of the cell’s behavior.

Modelling and analysis of train-track-subgrade-soil dynamic interaction subjected to the interfacial damage of slab induced by uneven settlement

In this paper, a dynamic model is established to investigate the dynamic behavior of train-track-subgrade-soil (TTSS) interaction. The effects of interfacial damage of the track slab induced by soil settlement on the dynamic interaction system are considered. The model framework is established by the finite element method. The soil settlement-induced track deformation is calculated by a practical iteration algorithm, where the nonlinear interfacial damage is simulated by the cohesive zone model. The simulation model is verified by comparison with other models. In regards to the excitations of the dynamic TTSS interaction system, two types of track irregularities are considered, namely the conventional track irregularities generated by known spectrums, and the additional irregularities caused by soil settlement. In the numerical study, the dynamic performances of the TTSS interaction subjected to interfacial damage, and soil settlement are compared. Next, the short wavelength irregularity is discussed as well. From the results, the vibration enhancement can be observed in the time and frequency domain. The interfacial damage of the track enhances the vibration both in low- and high-frequency domains, while the impacts of settlement are only observed in the frequency band of 0∼3 Hz. The frequency band of vibrations triggered by short wavelength irregularities is correlated with its wavelength range. Moreover, the settlement with different wavelengths and amplitudes is studied. It is shown that the increase of settlement amplitude and decrease of settlement wavelength lead to higher damage degree in amplitude and wider spatial distribution. In regards to the dynamic responses, the vehicle accelerations, wheel-rail contact forces, track displacement, and soil displacement are more sensitive to the settlement amplitudes varying from 10 to 80 mm, while the sensitive settlement wavelength is concentrated in 20 to 40 m.

Real-time deformable SLAM with geometrically adapted template for dynamic monocular laparoscopic scenes.

Intraoperative reconstruction of endoscopic scenes is a key technology for surgical navigation systems. The accuracy and efficiency of 3D reconstruction directly determine the effectiveness of navigation systems in a variety of clinical applications. While current deformable SLAM algorithms can meet real-time requirements, their underlying reliance on regular templates still makes it challenging to efficiently capture abrupt geometric features within scenes, such as organ contours and surgical margins. We propose a novel real-time monocular deformable SLAM algorithm with geometrically adapted template. To ensure real-time performance, the proposed algorithm consists of two threads: a deformation mapping thread updates the template at keyframe rate and a deformation tracking thread estimates the camera pose and the deformation at frame rate. To capture geometric features more efficiently, the algorithm first detects salient edge features using a pre-trained contour detection network and then constructs the template through a triangulation method with guidance of the salient features. We thoroughly evaluated this method on Mandala and Hamlyn datasets in terms of accuracy and performance. The results demonstrated that the proposed method achieves better accuracy with 0.75-7.95% improvement and achieves consistent effectiveness in data association compared with the closest method. This study verified an adaptive template does improve the performance of reconstruction of dynamic laparoscopic Scenes with abrupt geometric features. However, further exploration is needed for applications in laparoscopic surgery with incisal margins caused by surgical instruments. This research serves as a crucial step toward enhanced automatic computer-assisted navigation in laparoscopic surgery. Code is available at https://github.com/Tang257/SLAM-with-geometrically-adapted-template .

Influence of vibration on sub-ballast layer induced by loading application on a fouled track ballast

The railway track’s sub-ballast layer is important, but it is often neglected, leading to the contamination and blockage of voids, as well as track deformation and degradation. These issues occur when fouling materials infiltrate the subballast due to load-induced vibration. The purposes of this paper are to investigate the influence of vibration on the sub-ballast layer when loads are applied to a fouled ballast and to determine whether sub-ballast saturation should be ignored. A ballast box was fabricated to represent actual railway conditions and filled with 100 kg of ballast aggregates containing fouling materials (crushed ballast, sand, clay, and coal) proportional to the ballast weight. In addition, a vibratory compactor plate machine was used to simulate load on the fouled ballast, inducing vibrations that caused fouling materials to migrate into the sub-ballast. The results indicate that 18% of crushed ballast, 20% of sand, 20.7% of clay, and 15% of coal infiltrated the sub-ballast due to loading-induced vibration, and fouling infiltration percentages rose as vibration from loading increased. These percentages exceeded the standard 10% weight of fouling infiltration into the sub-ballast, indicating an unfavourable subballast condition and showing that sub-ballast saturation should not be ignored. These findings have significant implications for maintenance engineers, as they underscore the need for continuous monitoring and upkeep to ensure optimal sub- ballast performance.

Energy dissipation and seismic response reduction system for high-speed railway bridges based on multiple performance requirements

The emergence of high-speed railway bridges in regions with high seismic intensity has brought attention to the growing seismic challenges associated with these structures. Although the prevalent use of friction pendulum bearings for seismic isolation in China has proven effective in mitigating the seismic response of bridges, it falls short of meeting the safety standards required for high-speed trains. To address the limitations of existing isolation systems, this study employs a combined approach of numerical simulation and experimental research, leading to the invention of performance-controllable isolation bearing and multi-directional energy dissipation dampers. Mechanical models for both components were introduced, and design methods for their key parameters were established based on multi-level seismic defense requirements. By integrating these advancements, a novel cooperative seismic isolation system for high-speed railway bridges was created. Under the influence of moderate earthquakes, the system relies on the shear key to meet the stiffness requirements for normal service. During large earthquakes, the shear key is sheared off, and the damper provides momentary stiffness to control track deformation, enabling the safe stopping of trains. This combination forms a seismic isolation system during large earthquakes, ensuring the safety of railway bridges. The numerical analysis of a high-speed railway bridge employing a cooperative seismic isolation system demonstrates substantial mitigation in the response of both the pier bottom and pier top. This aligns with seismic requirements for the bridge structure. Additionally, the reduction in train track deformation meets safety standards, confirming the seismic performance of bridges and ensuring the reliability of train operations.

MicroBundleCompute: Automated segmentation, tracking, and analysis of subdomain deformation in cardiac microbundles.

Advancing human induced pluripotent stem cell derived cardiomyocyte (hiPSC-CM) technology will lead to significant progress ranging from disease modeling, to drug discovery, to regenerative tissue engineering. Yet, alongside these potential opportunities comes a critical challenge: attaining mature hiPSC-CM tissues. At present, there are multiple techniques to promote maturity of hiPSC-CMs including physical platforms and cell culture protocols. However, when it comes to making quantitative comparisons of functional behavior, there are limited options for reliably and reproducibly computing functional metrics that are suitable for direct cross-system comparison. In addition, the current standard functional metrics obtained from time-lapse images of cardiac microbundle contraction reported in the field (i.e., post forces, average tissue stress) do not take full advantage of the available information present in these data (i.e., full-field tissue displacements and strains). Thus, we present "MicroBundleCompute," a computational framework for automatic quantification of morphology-based mechanical metrics from movies of cardiac microbundles. Briefly, this computational framework offers tools for automatic tissue segmentation, tracking, and analysis of brightfield and phase contrast movies of beating cardiac microbundles. It is straightforward to implement, runs without user intervention, requires minimal input parameter setting selection, and is computationally inexpensive. In this paper, we describe the methods underlying this computational framework, show the results of our extensive validation studies, and demonstrate the utility of exploring heterogeneous tissue deformations and strains as functional metrics. With this manuscript, we disseminate "MicroBundleCompute" as an open-source computational tool with the aim of making automated quantitative analysis of beating cardiac microbundles more accessible to the community.