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Uncertainty quantification of CO2 storage using Bayesian model averaging and polynomial chaos expansion
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Degradation rate quantification of solid oxide fuel cell performance with and without Al2TiO5 addition
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Investigation and quantification of flow unsteadiness in shock-particle cloud interaction
This work aims to study the interaction of a shock wave with a cloud of particles to quantify flow unsteadiness and velocity fluctuations using particle-resolved direct numerical simulation (PR-DNS). Three cases are studied, with each case revealing one aspect of the intricate flow phenomena involved in this interaction. The unsteady interaction of a shock wave with a transverse array of particles reveals the origin of unsteadiness under the effect of mutual wave-wave and wave-wake interactions between the particles. In the second case, the interaction of a shock with a particle cloud is studied, with a focus on the interaction of the complex wave system with the vortical structure. A budget analysis of the vorticity equation reveals the sources of strong unsteadiness in the particle cloud. A detailed analysis of the velocity fluctuation and kinetic energy in the fluctuating motion is performed to ascertain the importance of the velocity fluctuations that arise from the strong unsteadiness. Here, an analogous analysis is presented, in the third case, for a gradually-induced flow on the same particle cloud along with a comparison to the shock induced case to assess the impulsive effect of shock on intensity of the fluctuating field statistics.
Creep anisotropy modeling and uncertainty quantification of an additively manufactured Ni-based superalloy
The advantages offered by additive manufacturing over traditional processes has driven a great deal of industrial and academic interest in recent years. However, the process is relatively new and requires additional investigation to become sufficiently mature for wide scale industrial adoption. Electron beam melting powder bed fusion is one technology that has shown promise for fabricating high temperature resistant materials such as nickel based superalloys. The resulting microstructures typically exhibit a strong fiber texture in the build direction giving rise to anisotropic time-dependent deformation behavior. In order to accelerate the qualification of these materials for industrial adoption accurate numerical models are needed for simulating their behavior. In this work a crystal plasticity model including non-Schmid effects is presented for capturing creep anisotropy observed in additively manufactured IN738LC. The model is calibrated via a probabilistic framework where model parameters are treated as random variables. An iterative sequential design strategy is utilized to efficiently identify the probability density of the unknown model parameters. As a case study the model is utilized to investigate the behavior of randomly oriented equiaxed grain clusters sometimes observed embedded in the additively manufactured columnar structure. A synthetic realization is simulated and uncertainty is propagated through to the full-field response. Results indicate that these features are the source of significant creep relaxation and strain accumulation which partially explains observed grain boundary decohesion at these locations.
In situ quantification of fracture slip induced by hydraulic injections in a deep borehole: A comparison of two different borehole techniques
In situ measurements of fracture deformation during fluid injection are rare, yet essential for understanding the mechanical response of fractured rock. In this study, we evaluate the reliability of two methods by comparing their slip vector estimates: high-resolution borehole acoustic televiewer images captured before and after injection tests, and displacement data from a three-component borehole deformation probe recorded during the injections. Acoustic televiewer images capture only final in-plane displacement, whereas three-component borehole deformation measurements provide full 3D, transient fracture movement. Four injection tests in a fractured granitic rock mass along an inclined borehole at the Bedretto Underground Laboratory (Switzerland), beneath more than 1100 m of overburden, were analyzed. The two methods yielded consistent kinematics and comparable slip magnitudes, typically in the range of 0.2 – 0.6 mm. Angular differences between estimated slip directions ranged from 0.2° to 28°. For two test intervals with pre-existing fractures optimally oriented for slip, the measured slip vectors agreed with forward-modeled slip vectors based on the regional in situ stress field, supporting the Wallace–Bott hypothesis. Measurable shear displacement was identified in two test intervals containing fractures oriented nearly perpendicular to the least principal stress, including a newly formed hydraulic fracture. This demonstrates that even fractures unfavorably oriented for slip can undergo shear due to local stress perturbations around an inclined borehole.
Quantification of Pediatric Abdominal Organ Motion With a 4-Dimensional Magnetic Resonance Imaging Method
Purpose: To characterize respiration-induced abdominal organ motion in children receiving radiation treatment with a 4-dimensional (4D) magnetic resonance imaging (MRI) method. Methods and Materials: We analyzed free-breathing coronal 4D MRI datasets acquired from 35 patients (aged 1-20 years) with abdominal tumors. A deformable image registration of the 4D MRI datasets was performed to derive motion trajectories of selected anatomic landmarks, from which organ motions were quantified. The association between organ motion and patient characteristics was investigated and compared with previous studies. The relation between patient height and organ motion was further investigated to predict organ motion in prospective patients. Results: Organ motion and its individual variation were reduced in younger patients (eg, kidney peak-to-peak motion <5 mm for all but 1 patient aged ≤8 years), although special motion management may be warranted in some adolescents. The liver and spleen exhibited greater motion than did the kidneys, while intraorgan variation was present. The motions in the liver and kidneys agreed with those reported by the previous 4D computed tomography studies. Individual variations of organ motion in younger patients were due, in part, to changes in respiration rate, which ostensibly reflected the effect of anesthesia. The prediction of organ motion was limited by large individual variations, particularly for older patients. Conclusions: The 4D MRI acquisition method and motion analysis described in this study provide a nonionizing approach to understand age-associated organ motion, which aids in the planning of abdominal radiation therapy for pediatric patients. Use of 4D MRI facilitates monitoring of changes in target motion patterns during treatment courses and in various studies of the effect of organ motion on radiation treatment.
High-Resolution pO2 Imaging Improves Quantification of the Hypoxic Fraction in Tumors During Radiation Therapy
The extreme microscopic heterogeneity of tumors makes it difficult to characterize tumor hypoxia. We evaluated how changes in the spatial resolution of oxygen imaging could alter measures of tumor hypoxia and their correlation to radiation therapy response.
Quantification of Intrafraction and Interfraction Tumor Motion Amplitude and Prediction Error for Different Liver Tumor Trajectories in Cyberknife Synchrony Tracking
To research the fiducial-based, real-time tracking intrafraction (during the fraction [intra-]) and interfraction (between fractions [inter-]) tumor respiration amplitude, motion trajectory, and prediction error and quantify their relationships for different types of motion trajectories during Cyberknife-based stereotactic ablation radiotherapy.
Quantification of Oxygen Depletion During FLASH Irradiation In Vitro and In Vivo
Delivery of radiation at ultrahigh dose rates (UHDRs), known as FLASH, has recently been shown to preferentially spare normal tissues from radiation damage compared with tumor tissues. However, the underlying mechanism of this phenomenon remains unknown, with one of the most widely considered hypotheses being that the effect is related to substantial oxygen depletion upon FLASH, thereby altering the radiochemical damage during irradiation, leading to different radiation responses of normal and tumor cells. Testing of this hypothesis would be advanced by direct measurement of tissue oxygen in vivo during and after FLASH irradiation.
AI-Based Radiation Dose Quantification for Estimation of Heart Disease Risk in Breast Cancer Survivors After Radiation Therapy
To investigate whether the dose planned for cardiac structures is associated with the risk of heart disease (HD) in patients with breast cancer treated with radiation therapy, and whether this association is modified by the presence of coronary artery calcification (CAC).
AI-Based Quantification of Planned Radiation Therapy Dose to Cardiac Structures and Coronary Arteries in Patients With Breast Cancer
The purpose of this work is to develop and evaluate an automatic deep learning method for segmentation of cardiac chambers and large arteries, and localization of the 3 main coronary arteries in radiation therapy planning on computed tomography (CT). In addition, a second purpose is to determine the planned radiation therapy dose to cardiac structures for breast cancer therapy.
Quantification of the Resilience and Vulnerability of HIV-1 Native Glycan Shield at Atomistic Detail
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Deep Learning-Based quantifications of methane emissions with field applications
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Consequences of product inhibition in the quantification of kinetic parameters
While the potential for product inhibition in catalytic reactions is well known, the impact of neglected inhibition on measured kinetic parameters is often overlooked. The presence of product inhibition, most often caused by the competitive adsorption of products with reactants on catalytic active sites, is difficult to determine a priori for an arbitrary catalytic system. The significance of product inhibition relies on the concentration of the products, their adsorption thermodynamics on catalytically relevant sites, and process parameters such as temperature and pressure. When inhibition is significant, however, apparent activation energies and reaction orders vary from the differential-reactor apparent activation energy by a factor of 1/(1 - δ), where δ is the total inhibition order (e.g., the factor (1 - δ) = 1.6 for a system with product inhibition of -0.6 order). This is illustrated here with the kinetics of NO oxidation over Cu ion clusters (Cu x O y ) in Cu-SSZ-13, for which the product NO 2 inhibits the forward reaction. Furthermore, in the presence of inhibition, when only reactants are fed to a flow reactor or placed in a batch reactor, there is often no practical conversion that is low enough to guarantee differential behavior. Inclusion of products in the feed solves this problem, allowing accurate determination of kinetic parameters such as apparent reaction orders and activation energies. We also demonstrate that evaluation of the necessity of co-feeding products to assure measurement of differential-reactor data in a given catalytic system is straightforward from a plot of the log of the rate (or conversion) versus the log of the space time in a flow reactor or elapsed time in a batch reactor. We encourage inclusion of this test in all kinetic analyses that are reasonably approximated by power law rate expressions.