Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “MOTION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

TU-F-17A-01: BEST IN PHYSICS (JOINT IMAGING-THERAPY) - An Automatic Toolkit for Efficient and Robust Analysis of 4D Respiratory Motion

Purpose: To provide an automatic image analysis toolkit to process thoracic 4-dimensional computed tomography (4DCT) and extract patient-specific motion information to facilitate investigational or clinical use of 4DCT. Methods: We developed an automatic toolkit in MATLAB to overcome the extra workload from the time dimension in 4DCT. This toolkit employs image/signal processing, computer vision, and machine learning methods to visualize, segment, register, and characterize lung 4DCT automatically or interactively. A fully-automated 3D lung segmentation algorithm was designed and 4D lung segmentation was achieved in batch mode. Voxel counting was used to calculate volume variations of the torso, lung and its air component, and local volume changes at the diaphragm and chest wall to characterize breathing pattern. Segmented lung volumes in 12 patients are compared with those from a treatment planning system (TPS). Voxel conversion was introduced from CT# to other physical parameters, such as gravity-induced pressure, to create a secondary 4D image. A demon algorithm was applied in deformable image registration and motion trajectories were extracted automatically. Calculated motion parameters were plotted with various templates. Machine learning algorithms, such as Naive Bayes and random forests, were implemented to study respiratory motion. This toolkit is complementary to and will be integrated with the Computational Environment for Radiotherapy Research (CERR). Results: The automatic 4D image/data processing toolkit provides a platform for analysis of 4D images and datasets. It processes 4D data automatically in batch mode and provides interactive visual verification for manual adjustments. The discrepancy in lung volume calculation between this and the TPS is <±2% and the time saving is by 1–2 orders of magnitude. Conclusion: A framework of 4D toolkit has been developed to analyze thoracic 4DCT automatically or interactively, facilitating both investigational and clinical use. More software tools are under development for automatic analysis of other 4D imaging modalities. This research is in part supported by NIH (U54CA137788/132378) and City Seed FY13(Grant No. 93348-14 01). AY would like to thank MSKCC summer medical student research program supported by National Cancer Institute and hosted by Department of Medical Physics at MSKCC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Real-time ultrasound-tagging to track the 2D motion of the common carotid artery wall in vivo

Purpose: Tracking the motion of biological tissues represents an important issue in the field of medical ultrasound imaging. However, the longitudinal component of the motion (i.e., perpendicular to the beam axis) remains more challenging to extract due to the rather coarse resolution cell of ultrasound scanners along this direction. The aim of this study is to introduce a real-time beamforming strategy dedicated to acquire tagged images featuring a distinct pattern in the objective to ease the tracking. Methods: Under the conditions of the Fraunhofer approximation, a specific apodization function was applied to the received raw channel data, in real-time during image acquisition, in order to introduce a periodic oscillations pattern along the longitudinal direction of the radio frequency signal. Analytic signals were then extracted from the tagged images, and subpixel motion tracking of the intima–media complex was subsequently performed offline, by means of a previously introduced bidimensional analytic phase-based estimator. Results: The authors’ framework was applied in vivo on the common carotid artery from 20 young healthy volunteers and 6 elderly patients with high atherosclerosis risk. Cine-loops of tagged images were acquired during three cardiac cycles. Evaluated against reference trajectories manually generated by three experienced analysts, the mean absolute tracking error was 98 ± 84 μm and 55 ± 44 μm in the longitudinal and axial directions, respectively. These errors corresponded to 28% ± 23% and 13% ± 9% of the longitudinal and axial amplitude of the assessed motion, respectively. Conclusions: The proposed framework enables tagged ultrasound images of in vivo tissues to be acquired in real-time. Such unconventional beamforming strategy contributes to improve tracking accuracy and could potentially benefit to the interpretation and diagnosis of biomedical images.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

A hybrid approach for fusing 4D-MRI temporal information with 3D-CT for the study of lung and lung tumor motion

Purpose: Accurate visualization of lung motion is important in many clinical applications, such as radiotherapy of lung cancer. Advancement in imaging modalities [e.g., computed tomography (CT) and MRI] has allowed dynamic imaging of lung and lung tumor motion. However, each imaging modality has its advantages and disadvantages. The study presented in this paper aims at generating synthetic 4D-CT dataset for lung cancer patients by combining both continuous three-dimensional (3D) motion captured by 4D-MRI and the high spatial resolution captured by CT using the authors’ proposed approach. Methods: A novel hybrid approach based on deformable image registration (DIR) and finite element method simulation was developed to fuse a static 3D-CT volume (acquired under breath-hold) and the 3D motion information extracted from 4D-MRI dataset, creating a synthetic 4D-CT dataset. Results: The study focuses on imaging of lung and lung tumor. Comparing the synthetic 4D-CT dataset with the acquired 4D-CT dataset of six lung cancer patients based on 420 landmarks, accurate results (average error <2 mm) were achieved using the authors’ proposed approach. Their hybrid approach achieved a 40% error reduction (based on landmarks assessment) over using only DIR techniques. Conclusions: The synthetic 4D-CT dataset generated has high spatial resolution, has excellent lung details, and is able to show movement of lung and lung tumor over multiple breathing cycles.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-C-210-01: Are Clinically Relevant Dosimetric Endpoints Significantly Better with Gating of Lung SBRT Vs. ITV-Based Treatment?: Results of a Large Cohort Investigation Analyzing Predictive Dosimetric Indicators as a Function of Tumor Volume and Motion Amplitude

Purpose: To quantitatively compare patient internal target volume (ITV)-based plans with retrospectively generated gated plans to evaluate potential dosimetric improvements in lung toxicity from gated radiotherapy. Methods: Evaluation was conducted for 150 stereotactic body radiation therapy (SBRT) treatment plans for 128 early-stage (T1–T3, <5cm) NSCLC patients. PTV margins were: ITV+5 mm (ITV-plan) and GTV+5 mm (Gated-plan). ITV-based and gated treatment plans were compared on the same free-breathing CT. ITV-based plan constraints were used to re-optimize and recalculate new gated plans. Plans were generated for 3 fractionation regimens: 3×18Gy, 4×12Gy (original), and 5×10Gy. Physical dose was converted to equivalent dose in 2Gy fractions (EQD2), which was used to determine mean lung dose (MLD) and percent volume of lung receiving ≥20Gy (V20). MLD and V20 differences between gating and ITV-based plans were analyzed as a function of both three-dimensional (3D) motion and tumor volume. The low dose region, V5, was also evaluated. Results: MLD and V20 differences between gated and ITV-based plans were larger for lower (1.48±1.32Gy and 1.44±1.29%) than for upper lobe tumors (0.89±0.74Gy and 0.92±0.71%) due to smaller tumor motion (2.9±3.4mm) compared to lower lobe tumors (8.1±6.1mm). Average differences of <1–2% were noted in V5 between ITV and gated plans. Dosimetric differences between gating and ITV-based methods increased with increasing tumor motion and decreasing tumor volume. Overall, average MLD (8.04±3.92Gy) and V20 (8.29±4.33%) values for ITV-based plans were already well below clinical guidelines, even for the 3×18Gy dose scheme, for which largest differences were noted relative to gated plans. Similar results were obtained for 5×10Gy and 4×12Gy regimens. Conclusion: Clinically relevant improvement in pulmonary toxicity, based on predictors of radiation pneumonitis (MLD and V20) was not generally observed, though improvement for tumors with 3D motion >15 mm, mainly concentrated in peripheral lower lobe tumors, may be considered clinically relevant. Work supported in part by a grant from Varian Medical systems, Palo Alto, CA.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-D-207-05: Real-Time Intrafractional Motion Tracking During VMAT Delivery Using a Conventional Elekta CBCT System

Purpose: Real-time kV projection streaming capability has become recently available for Elekta XVI version 5.0. This study aims to investigate the feasibility and accuracy of real-time fiducial marker tracking during CBCT acquisition with or without simultaneous VMAT delivery using a conventional Elekta linear accelerator. Methods: A client computer was connected to an on-board kV imaging system computer, and receives and processes projection images immediately after image acquisition. In-house marker tracking software based on FFT normalized cross-correlation was developed and installed in the client computer. Three gold fiducial markers with 3 mm length were implanted in a pelvis-shaped phantom with 36 cm width. The phantom was placed on a programmable motion platform oscillating in anterior-posterior and superior-inferior directions simultaneously. The marker motion was tracked in real-time for (1) a kV-only CBCT scan with treatment beam off and (2) a kV CBCT scan during a 6-MV VMAT delivery. The exposure parameters per projection were 120 kVp and 1.6 mAs. Tracking accuracy was assessed by comparing superior-inferior positions between the programmed and tracked trajectories. Results: The projection images were successfully transferred to the client computer at a frequency of about 5 Hz. In the kV-only scan, highly accurate marker tracking was achieved over the entire range of cone-beam projection angles (detection rate / tracking error were 100.0% / 0.6±0.5 mm). In the kV-VMAT scan, MV-scatter degraded image quality, particularly for lateral projections passing through the thickest part of the phantom (kV source angle ranging 70°-110° and 250°-290°), resulting in a reduced detection rate (90.5%). If the lateral projections are excluded, tracking performance was comparable to the kV-only case (detection rate / tracking error were 100.0% / 0.8±0.5 mm). Conclusion: Our phantom study demonstrated a promising Result for real-time motion tracking using a conventional Elekta linear accelerator. MV-scatter suppression is needed to improve tracking accuracy during MV delivery. This research is funded by Motion Management Research Grant from Elekta.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-E-T-330: Dosimetric Impact of Intrafraction Respiratory Motion On Lung SBRT Treatment Using Cyberknife 0-View Tracking Mode

Purpose: To investigate the influence of respiratory motion on the delivered dose in lung stereotactic body radiotherapy (SBRT) using Cyberknife (CK) 0-View tracking mode. Methods: CT scans at inspiration and expiration of an anthropomorphic motion phantom were fused base on the spine and an internal target volume (ITV) was created. A 5mm expansion around the ITV resulted in the planning target volume. Three CK plans were generated in Accuray MultiPlan using Lung Optimization Tracking 0-View technique with the minimum MU per beam set to (a) 5MU, (b) 15MU and (c) 30MU, respectively. Doses were calculated on the expiration CT using Monte-Carlo algorithm. Each plan was delivered 5 times with a range of different starting phases in the respiratory cycle to assess the dose variation due to interplay effect. The delivered dose was measured with EBT3 Gafchromic film which was inserted in the moving target of the phantom. The target motion range is 3 cm in superior-inferior (SI) direction with the breathing period of 5 seconds. Results: The gamma analysis (5%/2mm) of the dose with the films in the transverse plane resulted in average passing rate of 95.5±4.1%, 96.7±2.6%, and 96.2±2.5% for plan (a), (b), and (c), respectively. For the sagittal films, the average passing rate was 91.1±4.9%, 92.1±3.6%, and 92.3±2.9% for the three plans, respectively. The disagreement between measurement and dose calculations were mostly on the target edges in SI direction. The mean measured versus calculated dose differences at the edge of target in SI direction were (a) 3.9±4.8%, (b) 2.4±3.3%, and (c) 2.2±3.2% for the three plans, respectively. Conclusions: The plans with low-MU beams (below 10MU) tend to cause slightly larger dose variation. However in terms of target coverage, the overall clinical dosimetric impact of the intrafraction respiratory motion in lung SBRT is insignificant when averaged over 3∼5 fractions.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

TH-CD-207A-07: Prediction of High Dimensional State Subject to Respiratory Motion: A Manifold Learning Approach

Purpose: The development of high dimensional imaging systems (e.g. volumetric MRI, CBCT, photogrammetry systems) in image-guided radiotherapy provides important pathways to the ultimate goal of real-time volumetric/surface motion monitoring. This study aims to develop a prediction method for the high dimensional state subject to respiratory motion. Compared to conventional linear dimension reduction based approaches, our method utilizes manifold learning to construct a descriptive feature submanifold, where more efficient and accurate prediction can be performed. Methods: We developed a prediction framework for high-dimensional state subject to respiratory motion. The proposed method performs dimension reduction in a nonlinear setting to permit more descriptive features compared to its linear counterparts (e.g., classic PCA). Specifically, a kernel PCA is used to construct a proper low-dimensional feature manifold, where low-dimensional prediction is performed. A fixed-point iterative pre-image estimation method is applied subsequently to recover the predicted value in the original state space. We evaluated and compared the proposed method with PCA-based method on 200 level-set surfaces reconstructed from surface point clouds captured by the VisionRT system. The prediction accuracy was evaluated with respect to root-mean-squared-error (RMSE) for both 200ms and 600ms lookahead lengths. Results: The proposed method outperformed PCA-based approach with statistically higher prediction accuracy. In one-dimensional feature subspace, our method achieved mean prediction accuracy of 0.86mm and 0.89mm for 200ms and 600ms lookahead lengths respectively, compared to 0.95mm and 1.04mm from PCA-based method. The paired t-tests further demonstrated the statistical significance of the superiority of our method, with p-values of 6.33e-3 and 5.78e-5, respectively. Conclusion: The proposed approach benefits from the descriptiveness of a nonlinear manifold and the prediction reliability in such low dimensional manifold. The fixed-point iterative approach turns out to work well practically for the pre-image recovery. Our approach is particularly suitable to facilitate managing respiratory motion in image-guide radiotherapy. This work is supported in part by NIH grant R01 CA169102-02.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

TH-EF-BRA-11: Feasibility of Super-Resolution Time-Resolved 4DMRI for Multi-Breath Volumetric Motion Simulation in Radiotherapy Planning

Purpose: To develop a novel super-resolution time-resolved 4DMRI technique to evaluate multi-breath, irregular and complex organ motion without respiratory surrogate for radiotherapy planning. Methods: The super-resolution time-resolved (TR) 4DMRI approach combines a series of low-resolution 3D cine MRI images acquired during free breathing (FB) with a high-resolution breath-hold (BH) 3DMRI via deformable image registration (DIR). Five volunteers participated in the study under an IRB-approved protocol. The 3D cine images with voxel size of 5×5×5 mm{sup 3} at two volumes per second (2Hz) were acquired coronally using a T1 fast field echo sequence, half-scan (0.8) acceleration, and SENSE (3) parallel imaging. Phase-encoding was set in the lateral direction to minimize motion artifacts. The BH image with voxel size of 2×2×2 mm{sup 3} was acquired using the same sequence within 10 seconds. A demons-based DIR program was employed to produce super-resolution 2Hz 4DMRI. Registration quality was visually assessed using difference images between TR 4DMRI and 3D cine and quantitatively assessed using average voxel correlation. The fidelity of the 3D cine images was assessed using a gel phantom and a 1D motion platform by comparing mobile and static images. Results: Owing to voxel intensity similarity using the same MRI scanning sequence, accurate DIR between FB and BH images is achieved. The voxel correlations between 3D cine and TR 4DMRI are greater than 0.92 in all cases and the difference images illustrate minimal residual error with little systematic patterns. The 3D cine images of the mobile gel phantom preserve object geometry with minimal scanning artifacts. Conclusion: The super-resolution time-resolved 4DMRI technique has been achieved via DIR, providing a potential solution for multi-breath motion assessment. Accurate DIR mapping has been achieved to map high-resolution BH images to low-resolution FB images, producing 2Hz volumetric high-resolution 4DMRI. Further validation and improvement are still required prior to clinical applications. This study is in part supported by the NIH (U54CA137788/U54CA132378).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Sci-Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques - 05: A novel respiratory motion simulation program for VMAT treatment plans: a phantom validation study

Purpose: To develop and validate a computational method to simulate craniocaudal respiratory motion in a VMAT treatment plan. Methods: Three 4DCTs of the QUASAR respiratory motion phantom were acquired with a 2cm water-density spherical tumour embedded in cedar to simulate lung. The phantom was oscillating sinusoidally with an amplitude of 2cm and periods of 3, 4, and 5 seconds. An ITV was contoured and 5mm PTV margin was added. High and a low modulation factor VMAT plans were created for each scan. An in-house program was developed to simulate respiratory motion in the treatment plans by shifting the MLC leaf positions relative to the phantom. Each plan was delivered to the phantom and the dose was measured using Gafchromic film. The measured and calculated plans were compared using an absolute dose gamma analysis (3%/3mm). Results: The average gamma pass rate for the low modulation plan and high modulation plans were 91.1% and 51.4% respectively. The difference between the high and low modulation plans gamma pass rates is likely related to the different sampling frequency of the respiratory curve and the higher MLC leaf speeds in the high modulation plan. A high modulation plan has a slower gantry speed and therefore samples the breathing cycle at a coarser frequency leading to inaccuracies between the measured and planned doses. Conclusion: A simple program, including a novel method for increasing sampling frequency beyond the control point frequency, has been developed to simulate respiratory motion in VMAT plans by shifting the MLC leaf positions.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

On Relative Importance of Vehicular and Structural Motions in Defining Electrolyte Transport

Molecular motions of ionic and neutral electrolyte species determine transport properties at the continuum scale. These molecular motions can be classified as vehicular (e.g., cations moving with a solvation shell of neighboring solvent molecules) and structural (e.g., cations hopping from one solvation shell to another) motions. While literature studies have described the presence, and relative importance, of each of these motions in various electrolytes, a clear link to macroscopic transport properties has not been made. We herein establish this link by using the fluctuation-dissipation theorem to develop theoretical expressions connecting the molecular displacements to Stefan-Maxwell diffusivities. To illustrate the usefulness of the proposed equations, we study LiPF 6 in propylene carbonate as an exemplar electrolyte. We show that its transport behavior improves at all concentrations when structural diffusion of cations is promoted. On the other hand, boosting the cation vehicular diffusion negatively affects the concentrated compositions. We extend this understanding to a generalized electrolyte of a salt dissolved in a solvent. Our theory suggests that while structural diffusion influences Stefan-Maxwell diffusivities globally, vehicular diffusion is only relevant under certain conditions. Such guidelines are critical for a bottom-up design of electrolyte transport.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Evaluating the Trustworthiness of Explainable Artificial Intelligence (XAI) Methods Applied to Regression Predictions of Arctic Sea Ice Motion

Abstract Recent advances in explainable artificial intelligence (XAI) methods show promise for understanding predictions made by machine learning (ML) models. XAI explains how the input features are relevant or important for the model predictions. We train linear regression (LR) and convolutional neural network (CNN) models to make 1-day predictions of sea ice velocity in the Arctic from inputs of present-day wind velocity and previous-day ice velocity and concentration. We apply XAI methods to the CNN and compare explanations to variance explained by LR. We confirm the feasibility of using a novel XAI method [i.e., global layerwise relevance propagation (LRP)] to understand ML model predictions of sea ice motion by comparing it to established techniques. We investigate a suite of linear, perturbation-based, and propagation-based XAI methods in both local and global forms. Outputs from different explainability methods are generally consistent in showing that wind speed is the input feature with the highest contribution to ML predictions of ice motion, and we discuss inconsistencies in the spatial variability of the explanations. Additionally, we show that the CNN relies on both linear and nonlinear relationships between the inputs and uses nonlocal information to make predictions. LRP shows that wind speed over land is highly relevant for predicting ice motion offshore. This provides a framework to show how knowledge of environmental variables (i.e., wind) on land could be useful for predicting other properties (i.e., sea ice velocity) elsewhere. Significance Statement Explainable artificial intelligence (XAI) is useful for understanding predictions made by machine learning models. Our research establishes trustability in a novel implementation of an explainable AI method known as layerwise relevance propagation for Earth science applications. To do this, we provide a comparative evaluation of a suite of explainable AI methods applied to machine learning models that make 1-day predictions of Arctic sea ice velocity. We use explainable AI outputs to understand how the input features are used by the machine learning to predict ice motion. Additionally, we show that a convolutional neural network uses nonlinear and nonlocal information in making its predictions. We take advantage of the nonlocality to investigate the extent to which knowledge of wind on land is useful for predicting sea ice velocity elsewhere.

Hoffman, Lauren [Scripps Institution of Oceanograp↗
DOE OSTI2015

Analysis of Ground Motion from An Underground Chemical Explosion

Here in this paper we investigate the excitation and propagation of far-field seismic waves from the 905 kg trinitrotoluene equivalent underground chemical explosion SPE-3 recorded during the Source Physics Experiment (SPE) at the Nevada National Security Site. The recorded far-field ground motion at short and long distances is characterized by substantial shear-wave energy, and large azimuthal variations in P-and S-wave amplitudes. The shear waves observed on the transverse component of sensors at epicentral distances <50 m suggests they were generated at or very near the source. The relative amplitude of the shear waves grows as the waves propagate away from the source. We analyze and model the shear-wave excitation during the explosion in the 0.01–10 Hz frequency range, at epicentral distances of up to 1 km. We used two simulation techniques. One is based on the empirical isotropic Mueller–Murphy (MM) (Mueller and Murphy, 1971) nuclear explosion source model, and 3D anelastic wave propagation modeling. The second uses a physics-based approach that couples hydrodynamic modeling of the chemical explosion source with anelastic wave propagation modeling. Comparisons with recorded data show the MM source model overestimates the SPE-3 far-field ground motion by an average factor of 4. The observations show that shear waves with substantial high-frequency energy were generated at the source. However, to match the observations additional shear waves from scattering, including surface topography, and heterogeneous shallow structure contributed to the amplification of far-field shear motion. Comparisons between empirically based isotropic and physics-based anisotropic source models suggest that both wave-scattering effects and near-field nonlinear effects are needed to explain the amplitude and irregular radiation pattern of shear motion observed during the SPE-3 explosion.

58 GEOSCIENCES↗
DOE OSTI2016

Kinematic Ground-Motion Simulations on Rough Faults Including Effects of 3D Stochastic Velocity Perturbations

Here, we describe a methodology for generating kinematic earthquake ruptures for use in 3D ground–motion simulations over the 0–5 Hz frequency band. Our approach begins by specifying a spatially random slip distribution that has a roughly wavenumber–squared fall–off. Given a hypocenter, the rupture speed is specified to average about 75%–80% of the local shear wavespeed and the prescribed slip–rate function has a Kostrov–like shape with a fault–averaged rise time that scales self–similarly with the seismic moment. Both the rupture time and rise time include significant local perturbations across the fault surface specified by spatially random fields that are partially correlated with the underlying slip distribution. We represent velocity–strengthening fault zones in the shallow (<5 km) and deep (>15 km) crust by decreasing rupture speed and increasing rise time in these regions. Additional refinements to this approach include the incorporation of geometric perturbations to the fault surface, 3D stochastic correlated perturbations to the P– and S–wave velocity structure, and a damage zone surrounding the shallow fault surface characterized by a 30% reduction in seismic velocity. We demonstrate the approach using a suite of simulations for a hypothetical Mw 6.45 strike–slip earthquake embedded in a generalized hard–rock velocity structure. The simulation results are compared with the median predictions from the 2014 Next Generation Attenuation–West2 Project ground–motion prediction equations and show very good agreement over the frequency band 0.1–5 Hz for distances out to 25 km from the fault. Additionally, the newly added features act to reduce the coherency of the radiated higher frequency (f>1 Hz) ground motions, and homogenize radiation–pattern effects in this same bandwidth, which move the simulations closer to the statistical characteristics of observed motions as illustrated by comparison with recordings from the 1979 Imperial Valley earthquake.

58 GEOSCIENCES↗
DOE OSTI2017

CFD-DEM Onset of Motion Analysis for Application to Bed Scour Risk Assessment

This CFD study with DEM was done as a part of the Federal Highway Administration’s (FHWA’s) effort to improve scour design procedures. The Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model, available in CD-Adapco’s StarCCM+ software, was used to simulate multiphase systems, mainly those which combine fluids and solids. In this method the motion of discrete solids is accounted for by DEM, which applies Newton's laws of motion to every particle. The flow of the fluid is determined by the local averaged Navier–Stokes equations that can be solved using the traditional CFD approach. The interactions between the fluid phase and solids phase are modeled by use of Newton's third law. The inter-particle contact forces are included in the equations of motion. Soft-particle formulation is used, which allows particles to overlap. In this study DEM was used to model separate sediment grains and spherical particles laying on the bed with the aim to analyze their movement due to flow conditions. Critical shear stress causing the incipient movement of the sediment was established and compared to the available experimental data. An example of scour around a cylindrical pier is considered. Various depths of the scoured bed and flow conditions were taken into account to gain a better understanding of the erosion forces existing around bridge foundations. The decay of these forces with increasing scour depth was quantified with a ‘decay function’, which shows that particles become increasingly less likely to be set in motion by flow forces as a scour hole increases in depth. Computational and experimental examples of the scoured bed around a cylindrical pier are presented.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Ground Motion Inputs for the Seismic Shake Table Test

Currently, spent nuclear fuel (SNF) is stored in on-site independent spent-fuel storage installations (ISFSIs) at seventythree (73) nuclear power plants (NPPs) in the US. Because a site for geologic repository for permanent disposal of SNF has not been constructed, the SNF will remain in dry storage significantly longer than planned. During this time, the ISFSIs, and potentially consolidated storage facilities, will experience earthquakes of different magnitudes. The dry storage systems are designed and licensed to withstand large seismic loads. When dry storage systems experience seismic loads, there are little data on the response of SNF assemblies contained within them. The Spent Fuel Waste Disposition (SFWD) program is planning to conduct a full-scale seismic shake table test to close the gap related to the seismic loads on the fuel assemblies in dry storage systems. This test will allow for quantifying the strains and accelerations on surrogate fuel assembly hardware and cladding during earthquakes of different magnitudes and frequency content. The main component of the test unit will be the full-scale NUHOMS 32 PTH2 dry storage canister. The canister will be loaded with three surrogate fuel assemblies and twenty-nine dummy assemblies. Two dry storage configurations will be tested – horizontal and vertical above-ground concrete overpacks. These configurations cover 91% of the current dry storage configurations. The major input into the shake table test are the seismic excitations or the earthquake ground motions – acceleration time histories in two horizontal and one vertical direction that will be applied to the shake table surface during the tests. The shake table surface represents the top of the concrete pad on which a dry storage system is placed. The goal of the ground motion task is to develop the ground motions that would be representative of the range of seismotectonic and other conditions that any site in the Western US (WUS) or Central Eastern US (CEUS) might entail. This task is challenging because of the large number of the ISFSI sites, variety of seismotectonic and site conditions, and effects that soil amplification, soil-structure interaction, and pad flexibility may have on the ground motions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Understanding the Seismic Ground Motion Spatial Variability Using Network Analysis Community Detection

This project is to explore ground motion spatial distribution using a new approach graph-based network analysis. In this study, we combine a large-N seismic array and graph analytics to explore spatial variability and correlation at a local scale using small local and regional earthquakes. In this method, each seismic station is modeled as a node and the similarities of the waveforms that represent ground motions between two stations are modeled as edges. By analyzing this graph network using the similarity matrices and community detection algorithm, we can group the stations spatially with similar patterns. A random forest algorithm is used to reveal the important features that affect the spatial grouping. The result suggests site conditions, and how they interact with the incident seismic wavefield, strongly condition the spatial correlation of ground motion. Future progress in characterizing ground motion spatial variability will require dense wavefield measurements, either through nodal deployments, or perhaps distributed acoustic sensing measurements of seismic wavefields.

58 GEOSCIENCES↗
DOE OSTI2023

Moore Machine Motion Controls Refurbishment Statement of Work and Specification

Diamond Turning Machines known as “Moore” machines are used in the production of Potassium diHydrogen Phosphate (KDP) optics required for the National Ignition Facility (NIF). These machines are owned by the Department of Energy, as provided by Lawrence Livermore National Security LLC (LLNS). Moore Machines 1 and 2 are located at the Gooch & Housego (G&H) facility in Highland Heights, OH. The existing Aerotech motion controllers, motor drivers/amplifiers, input/output (I/O) hardware, control computer, software user interface, human machine interface (HMI), cabling, and encoders are beyond service life and require replacement. This Statement of Work (SoW) defines the motion control system refurbishment requirements for the Moore diamond turning machines designated Moore 1 and Moore 2. The motion controls system design shall include a motion control computer, control software, motor drive amplifiers and controllers, linear scale encoders, rotary encoders, HMI, power distribution, emergency stop (E-Stop) and interlocks, cabling, switches, solenoids, transducers, sensors, actuators, ancillary system interfaces, and related components necessary for a complete machine tool control system. The Subcontractor shall include effort to standardize systems between the two machines if reasonably possible.

42 ENGINEERING↗
DOE OSTI2025

Harvesting Subsea Water Motion to Provide Clean Electrical Power

This TEAMER project had three main objectives related to characterizing the performance of a vortex-induced vibration (VIV) marine energy harvesting device called the Whatever Input To Torsion (WITT). The first was to characterize the motion of the WITT device as it vibrates on top of a pipe in a natural tidal flow. The second was to measure how much electricity the WITT device generates when it is deployed on top of a pipe that is secured to the seabed with a lander. The third objective was to measure how much electricity the WITT device generates in the same configuration but with a longer pipe. This TEAMER project succeeded in satisfying the first objective by measuring the motion of the WITT device with an inertial measurement unit (IMU) mounted in the WITT housing. The motion was described by examining changes in the acceleration, pitch, roll, and yaw, and displacement. The frequency of the motion was characterized using spectral analysis. The TEAMER project succeeded in reaching the second objective by measuring the power produced by the WITT. It is reported here as the average and maximum power in hourly intervals. WITT Energy decided to not have us pursue the third objective of testing a longer pipe because the first test was unexpectedly successful at having the system vibrate at the target frequency. A longer pipe would have resulted in a decreased frequency and therefore not have been a useful test. Based on these findings, the decision was made to keep the same pipe length for both tests and improve on other aspects of the test structure that had failed during the first test. The key finding of this TEAMER project is that the WITT is capable of generating electricity in moderate flow speeds when it is in a housing that is attached to a 2.5 m pipe and secured to the seabed by a lander. This report contains the first power values for a VIV instrument that generates electricity from a pendulum swinging at the top of a long pipe. The experiment demonstrated that the vibration frequency of the device varied with the tidal current speed, which changed throughout a given tidal cycle. This meant that the desired peak frequency was not sustained for more than one hour. The success of this TEAMER test provides evidence that continued research in the area of electricity generation from VIV holds promise as a source of marine energy for offshore applications. Future tests should focus on refining the pipe length equations and improving the power take off system of the WITT power electronics. In addition, experiments aimed at expanded testing and evaluation (e.g. longer than one month) are needed to measure the power production at higher tidal current speeds and test the system's durability.

Branch, Ruth A. (ORCID:0000000202356719)↗