Search NASA⌕ Search

SEARCH · Search NASA

Results for “verification study”

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 1,387 records · Page 77
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Verification suite for the application of the limiting surface density method to arrays of 9975 packages

Criticality Safety Engineering at the Savannah River Site's K-Area Complex seeks to reduce the computational burden of analysis for the K-Area Complex. By applying an adapted Limiting Surface Density hand calculation method, the need for lengthy detailed Monte Carlo models of the storage arrays may be reduced or eliminated. After promising initial results using models of idealized but heterogeneous packages, application of the method to large arrays of highly heterogeneous 9975 shipping packages is attempted. A SCALE KENO-VI model of the 9975 package, with true dimensions and radial and axial heterogeneity is developed. A suite of array arrangements representing both arrays with equal number of packages per side (package-cubic) and arrays with unequal number of packages per side (non-cubic) are evaluated in SCALE. The cubic arrangements are used to derive the 9975-specific material and geometry constants for the LSD method. These constants are then used to implement the LSD method and compare the LSD- predicted critical mass per package to SCALE-predicted critical mass per package. Sensitivities to certain material and geometric nuances are evaluated for inclusion in the verification suite. Finally, the ability of the method to predict neutron multiplication changes induced by fissile mass changes is examined as a segue for evaluating credible abnormal conditions with the LSD method. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

Integral and Separate Effects Test Facilities To Support Water Cooled Small Modular Reactors: A Review

This study reviews previous experimental facilities and test programs relevant to water-cooled reactor system design and analysis to meet regulatory compliances. This study aims to find the best solution for designing the required experiments, obtaining necessary test data, and verifying the developed computer code/models to support the new reactor design and development while minimizing cost and time while leveraging experiences from previous facilities to minimize. Nuclear reactor licensing requires supportive design, analysis, and experimental results to ensure the safety of the full-scale prototype reactor in regular operation, as well as during postulated accident scenarios. These reactor design analyses are generally performed using system codes and other associated simulation tools that require assessment, verification and validation using an appropriate experimental dataset. Experimental facilities used for reactor system safety analysis and system code assessments are categorized into integral effects test (IET) and separate effects test (SET) facilities. Further, these IET and SET experiments and studies use geometrically scaled systems to reproduce the prototype system behavior at a reasonable cost, albeit with some scaling-related distortions. The design challenge of these model facilities is to identify and minimize scaling distortions while reproducing the most important operational phenomena in steady-state operation and in postulated accident scenarios. Lessons learned from previous experimental facilities, models, and correlations can support the development of new multipurpose, scaled, hybrid, integrated, and modular experimental facilities for advanced light water-cooled small modular reactors (SMRs). Successful operation of these facilities can significantly reduce upfront reactor development and demonstration costs and time to deployment.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRSDate not supplied

Beyond Guesswork: Code Verification for Acoustic Duct Mode Prediction

The code used in the work (Swirl) is a frequency-domain linearized Euler equation solver that is designed to predict the effect of acoustic liners on acoustic modes propagating in realistic sheared and swirling mean flows, guiding the design of more efficient liner configurations. The purpose of this study is to validate Swirl using the Method Of Manufactured Solutions (MMS). This study also investigated the effect of the integration and spatial differencing methods on the convergence for a given Manufactured Solution. In addition, the effect of boundary condition implementation was tested. Through rigorous validation of the Swirl code using the MMS, this research underscores the significance of integration and spatial differencing methods on convergence, evaluates boundary condition implementations, and systematically assesses the impact of various filters.

Code Verification↗
DOE OSTI2016

Predicting oxidation-limited lifetime of thin-walled components of NiCrW alloy 230

Using alloy 230 as an example, a generalized oxidation lifetime model for chromia-forming Ni-base wrought alloys is proposed, which captures the most important damaging oxidation effects relevant for component design: wall thickness loss, scale spallation, and the occurrence of breakaway oxidation. For deriving input parameters and for verification of the model approach, alloy 230 specimens with different thicknesses were exposed for different times at temperatures in the range 950–1050 °C in static air. The studies focused on thin specimens (0.2–0.5 mm) to obtain data for critical subscale depletion processes resulting in breakaway oxidation within reasonably achievable test times up to 3000 h. The oxidation kinetics and oxidation-induced subscale microstructural changes were determined by combining gravimetric data with results from scanning electron microscopy with energy dispersive X-ray spectroscopy. The modeling of the scale spallation and re-formation was based on the NASA cyclic oxidation spallation program, while a new model was developed to describe accelerated oxidation occurring after longer exposure times in the thinnest specimens. The calculated oxidation data were combined with the reservoir model equation, by means of which the relation between the consumption and the remaining concentration of Cr in the alloy was established as a function of temperature and specimen thickness. Based on this approach, a generalized lifetime diagram is proposed, in which wall thickness loss is plotted as a function of time, initial specimen thickness, and temperature. As a result, the time to reach a critical Cr level at the scale/alloy interface of 10 wt% is also indicated in the diagrams.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Urinary total arsenic and 8-hydroxydeoxyguanosine are associated with renal cell carcinoma in an area without obvious arsenic exposure

8-Hydroxydeoxyguanosine (8-OHdG) is one of the most reliable and abundant markers of DNA damage. The study was designed to explore the relationship between urinary 8-OHdG and renal cell carcinoma (RCC) and to investigate whether individuals with a high level of 8-OHdG would have a modified odds ratio (OR) of arsenic-related RCC. This case–control study was conducted with 132 RCC patients and 245 age- and sex-matched controls from a hospital-based pool between November 2006 and May 2009. Pathological verification of RCC was completed by image-guided biopsy or surgical resection of renal tumors. Urinary 8-OHdG levels were determined using liquid chromatography with tandem mass spectrometry (LC–MS/MS). Concentrations of urinary arsenic species, including inorganic arsenic, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), were determined by a high performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Level of urinary 8-OHdG was significantly associated with the OR of RCC in a dose–response relationship after multivariate adjustment. Urinary 8-OHdG was significantly related to urinary total arsenic. The greatest OR (3.50) was seen in the individuals with high urinary 8-OHdG and high urinary total arsenic. A trend test indicated that the OR of RCC was increased with one of these factors and was further increased with both (p = 0.002). In conclusion, higher urinary 8-OHdG was a strong predictor of the RCC. High levels of 8-OHdG combined with urinary total arsenic might be indicative of arsenic-induced RCC. -- Highlights: ► Urinary 8-OHdG was significantly related to urinary total arsenic. ► Higher urinary 8-OHdG was a strong predictor of RCC risk. ► Urinary 8-OHdG may modify arsenic related RCC risk.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Cyber‐physical system testbed for power system monitoring and wide‐area control verification

The electric power system is intrinsically a cyber‐physical system (CPS) with power flowing inthe physical system and information flowing in the cyber‐network. Testbeds arecrucial for understanding the cyber‐physical interactions and provideenvironments for prototyping novel applications. This study proposes afour‐layer architecture for CPS testbeds with emphases on communication networkemulation and networked physical components. A configurable software‐definednetwork is employed to bridge physical components with wide‐area applicationsfor closed‐loop control. In order to distribute physically coupled devices intomultiple software simulations, this study proposes a data broker setup based ona distributed messaging environment to achieve low‐latency data streaming. Thedecoupled design with data streaming allows for building testbed components asmodules and running them in a distributed manner. Case studies verify the databroker setup for low‐latency sensing and actuation, as well as the communicationemulation setup for the desired network latency. Also illustrated is a replayattack scenario using synchrophasors in the Western Electricity CoordinatingCouncil (WECC) 181‐bus system for demonstrating the closed‐loop cyber‐physicalsimulation capability of the testbed.

Cui, Hantao↗
DOE OSTI2018

Temporal variability largely explains top-down/bottom-up difference in methane emission estimates from a natural gas production region

Here, this study spatially and temporally aligns top-down and bottom-up methane emission estimates for a natural gas production basin, using multiscale emission measurements and detailed activity data reporting. We show that episodic venting from manual liquid unloadings, which occur at a small fraction of natural gas well pads, drives a factor-of-two temporal variation in the basin-scale emission rate of a US dry shale gas play. The midafternoon peak emission rate aligns with the sampling time of all regional aircraft emission studies, which target well-mixed boundary layer conditions present in the afternoon. A mechanistic understanding of emission estimates derived from various methods is critical for unbiased emission verification and effective greenhouse gas emission mitigation. Our results demonstrate that direct comparison of emission estimates from methods covering widely different timescales can be misleading.

03 NATURAL GAS↗
DOE OSTI2015

An approach for verifying biogenic greenhouse gas emissions inventories with atmospheric CO 2 concentration data

Verifying national greenhouse gas (GHG) emissions inventories is a critical step to ensure that reported emissions data to the United Nations Framework Convention on Climate Change (UNFCCC) are accurate and representative of a country’s contribution to GHG concentrations in the atmosphere. Verification could include a variety of evidence, but arguably the most convincing verification would be confirmation of a change in GHG concentrations in the atmosphere that is consistent with reported emissions to the UNFCCC. We report here on a case study evaluating this option based on a prototype atmospheric CO2 measurement network deployed in the Mid-Continent Region of the conterminous United States. We found that the atmospheric CO2 measurement data did verify the accuracy of the emissions inventory within the confidence limits of the emissions estimates, suggesting that this technology could be further developed and deployed more widely in the future for verifying reported emissions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Clinical manifestation of hemophilia A in the absence of mutations in the F8 gene that encodes FVIII: role of microRNAs

BACKGROUND Hemophilia A (HA) is associated with mutations in the F8 gene that expresses factor VIII (FVIII). Unexpectedly, HA also manifests in a small subset of individuals with no mutations (exonic or intronic) in their F8 gene. MicroRNAs (miRNAs) cause translational interference, affecting protein quality and stoichiometry. Here, by analyzing miRNAs of two patients from this subset, we evaluated miRNA‐based FVIII suppression as a testable hypothesis to explain FVIII deficiency in patients with HA with no F8 gene mutations. STUDY DESIGN AND METHODS To test the hypothesis, miRNA sequencing from two patients with mild and moderate HA with no mutations in their F8 gene, followed by experimental verification, was used to identify a group of upregulated miRNAs in patients with HA compared to normal controls; with binding sites in the 3′ untranslated region (UTR) of F8 messenger RNA (mRNA), a prerequisite for miRNA‐based gene regulation. From this pool, miR‐374b‐5p and miR‐30c‐5p, known to be expressed in human liver, where FVIII is expressed, were subjected to extensive characterization. RESULTS In two cell lines that constitutively express FVIII, we demonstrated that overexpression of miR‐374b or miR‐30c decreased FVIII expression, while an miR‐30c inhibitor partially restored FVIII expression. CONCLUSION These data support a role for microRNAs in fine‐tuning F8 gene regulation. Based on our findings, our current model suggests that in HA cases where the F8 gene is normal and is predicted to express normal levels of FVIII, F8 mRNA 3′ UTR targeting miRNAs may be responsible for a FVIII‐deficiency phenotype clinically manifesting as HA.

Jankowska, Katarzyna I.↗
DOE OSTI2014

WE-E-BRF-01: The ESTRO-AAPM Joint Symposium On Imaging for Proton Treatment Planning and Guidance

In this first inaugural joint ESTRO-AAPM session we will attempt to provide some answers to the problems encountered in the clinical application of particle therapy. Indeed the main advantage is that the physical properties of ion beams offer high ballistic accuracy for tightly conformal irradiation of the tumour volume, with excellent sparing of surrounding healthy tissue and critical organs, This also its Achilles' heel calling for an increasing role of imaging to ensure safe application of the intended dose to the targeted area during the entire course of fractionated therapy. We have three distinguished speakers addressing possible solutions. Katia Parodi (Ludwig Maximilians University, Munich, Germany) To date, Positron Emission Tomography (PET) is the only technique which has been already clinically investigated for in-vivo visualization of the beam range during or shortly after ion beam delivery. The method exploits the transient amount of β{sup 2}-activity induced in nuclear interactions between the primary beam and the irradiated tissue, depending on the ion beam species, the tissue elemental composition and physiological properties (in terms of biological clearance), as well as the time course of irradiation and imaging. This contribution will review initial results, ongoing methodological developments and remaining challenges related to the clinical usage of viable but often suboptimal instrumentation and workflows of PET-based treatment verification. Moreover, it will present and discuss promising new detector developments towards next-generation dedicated PET scanners relying on full-ring or dual-head designs for in-beam quasi real-time imaging. Denis Dauvergne (Institut de Physique Nucleaire de Lyon, Lyon, France) Prompt gamma radiation monitoring of hadron therapy presents the advantage of real time capability to measure the ion range. Both simulations and experiments show that millimetric verification of the range can be achieved at the pencil beam scale for active proton beam delivery in homogenous targets. The development of gamma cameras, that has been studied by several groups worldwide over the last years, now reaches - for some of them - the stage of being applicable in clinical conditions, with real size prototypes and count rate capability matching the therapeutic beam intensities. We will review the different concepts of gamma cameras, the advantages and limitations of this method, and the main challenges that should still be overcome before the widespread of prompt gamma quality assurance for proton and hadrontherapy. Jon Kruse (Mayo Clinic, Rochester, MN, USA) Treatment simulation images for proton therapy are used to determine proton stopping power and range in the patient. This talk will discuss the careful control of CT numbers and conversion of CT number to stopping power required in proton therapy. Imaging for treatment guidance of proton therapy also presents unique challenges which will be addressed. Among them are the enhanced relationship between internal anatomy changes and dosimetry, the need for imaging to support adaptive planning protocols, and high operational efficiency. Learning Objectives: To learn about the possibilities of using activation products to determine the range of particle beams in a patient treatment setting To be informed on an alternative methodology using prompt gamma detectors To understand the impact of the accuracy of the knowledge of the patient information with respect to the delivered treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-EF-304-03: 4D Monte Carlo Robustness Test for Proton Therapy

Purpose: Breathing motion and approximate dose calculation engines may increase proton range uncertainties. We address these two issues using a comprehensive 4D robustness evaluation tool based on an efficient Monte Carlo (MC) engine, which can simulate breathing with no significant increase in computation time. Methods: To assess the robustness of the treatment plan, multiple scenarios of uncertainties are simulated, taking into account the systematic and random setup errors, range uncertainties, and organ motion. Our fast MC dose engine, called MCsquare, implements optimized models on a massively-parallel computation architecture and allows us to accurately simulate a scenario in less than one minute. The deviations of the uncertainty scenarios are then reported on a DVH-band and compared to the nominal plan.The robustness evaluation tool is illustrated in a lung case by comparing three 60Gy treatment plans. First, a plan is optimized on a PTV obtained by extending the CTV with an 8mm margin, in order to take into account systematic geometrical uncertainties, like in our current practice in radiotherapy. No specific strategy is employed to correct for tumor and organ motions. The second plan involves a PTV generated from the ITV, which encompasses the tumor volume in all breathing phases. The last plan results from robust optimization performed on the ITV, with robustness parameters of 3% for tissue density and 8 mm for positioning errors. Results: The robustness test revealed that the first two plans could not properly cover the target in the presence of uncertainties. CTV-coverage (D95) in the three plans ranged respectively between 39.4–55.5Gy, 50.2–57.5Gy, and 55.1–58.6Gy. Conclusion: A realistic robustness verification tool based on a fast MC dose engine has been developed. This test is essential to assess the quality of proton therapy plan and very useful to study various planning strategies for mobile tumors. This work is partly funded by IBA (Louvain-la-Neuve, Belgium)

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-343: Dosimetric Investigation for Fluence Smoothing On VMAT Plans in Monaco for Head - Neck Cancers

Purpose: The study investigates the effect of fluence smoothing parameter on VMAT plans for ten head-neck cancer patients using Monaco5.00.04. Methods: VMAT plans were created using Monaco5.00.04 planning system for 10 head-neck patients. Four plans were generated for each patient using available smoothing parameters i.e. high, medium, low and off. The number of monitor units required to deliver 1 cGy was defined as a modulation degree; and was taken as a measure of plan complexity. Routinely used plan quality parameters Conformity index (CI) and Homogeneity index (HI) were used in the study. As a protocol our center, practices “medium” smoothing for clinical implementation. Plans with medium smoothing were opted as reference plans due to the clinical acceptance and dosimetric verifications made on these plans. Plans were generated by varying the smoothing parameter and re-optimization was done. The PTV was evaluated for D98%, D95%, D50%, D1% and prescription isodose volume (PIV). For critical organs; spine and parotids the parameters recorded were D1cc and Dmean respectively. Results: The cohort had the median prescription as 6000 cGy in the range of 6600 cGy - 4500 cGy. The modulation degree was observed to increase up to 6% from reference to the most complex plan. High smoothing had about 11% increase in segments which marginally (0.5 to 1%) increased the homogeneity index while conformity index remains constant. For spine the maximum D1cc was observed in medium smoothing as 4639.8 cGy, this plan was clinically accepted and dosimetrically verified. Similarly for parotids, the Dmean was 2011.9 cGy and 1817.05 cGy. Conclusion: The sensitivity of plan quality in terms of smoothing options (high, medium, low and off) available in Monaco 5.00.04 was resulted in minimal difference in terms of target coverage, conformity index and homogeneity index. Similarly changing smoothing did not result in any enhanced advantage in sparing of critical organs.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Establishing model credibility for process-microstructure-property relationships in additive manufacturing using exascale computing

Additive Manufacturing (AM) of alloys holds significant promise as a disruptive technology in various industries, yet its adoption is often hindered by challenges in achieving consistent part quality. These issues are primarily due to the complex process-microstructure-property (PSP) relationships inherent to AM. Computational models can greatly aid in understanding these relationships, but their widespread impact and adoption has been limited by a lack of validated, open-source, and computationally efficient PSP modeling frameworks and hardware limitations. Here, this study leverages the ExaAM software suite and data from the AMBench-2018 series of laser powder bed fusion (LPBF) benchmark experiments to perform a comprehensive model assessment, including verification, validation, sensitivity analysis, and uncertainty quantification. The RADICAL-EnTK workflow manager was used to perform an ensemble of heat transport, solidification, and mechanical response simulations on the exascale computer Frontier, considering uncertainties in critical model inputs such as laser spot size and nucleation parameters, and consisting of 125 explicit grain structure simulations and 7875 crystal plasticity simulations. For a selected location within the Inconel 625 AMBench-2018 test artifact, sensitivity analysis and uncertainty quantification were performed using the predicted distributions of grain structure and mechanical properties. Qualitative agreement was found between the predicted grain size and texture and the observed AMBench-2018 microstructure, the mean predicted yield stress was within 5% of the experimental measurement mean, and the mean predicted engineering stress at 5% strain was within 10% of the experimental measurement mean. The insights gained from development and validation of the ExaAM PSP modeling framework will help guide future directions for enhancing the credibility and reliability of PSP models in AM, thereby accelerating the adoption of AM technologies in various industries.

Additive manufacturing↗
DOE OSTI2016

Advanced Metering Installations – A Perspective from Federal Sites

This report is intended to provide guidance to the United States Department of Energy (DOE) and other federal agencies to highlight some of the existing practices related to advanced building metering systems. This study identified some of the existing actions related to advanced meter data and proposes how advanced metered data can be employed to develop robust cost effective measurement and verification (M&V) strategies. This report proposes an integrated framework on how advanced meter data can be used to identify energy conservation opportunities and to develop proactive M&V strategies to ensure that the savings for energy projects are being realized. This information will help improve metering, feedback, and dashboard implementations for reducing energy use at DOE facilities, based on lessons learned from various advanced metering implementations.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2019

DOE NETL Gas Hydrate Project FWP 65213: Kinetic Parameters for the Exchange of Hydrate Formers (Final Report)

This report documents the research activities sponsored by the U.S. Department of Energy, National Energy Technology Laboratory (NETL), by the Pacific Northwest National Laboratory (PNNL) for the gas hydrate project entitled, “Kinetic Parameters for the Exchange of Hydrate Formers.” This project started June 1, 2013 and concluded December 31, 2018, and comprised five budget periods, under FWP-65213. The overarching goal of this project was to gain an improved understanding of the dynamic processes of gas hydrate accumulations in geologic media by combining laboratory studies, numerical simulation, and analysis of shipboard infrared imaging of hydrate core samples. This project comprised four principal components: 1) fundamental laboratory investigations, 2) numerical simulator development and verification, 3) hydrate core characterization and analysis, and 4) applied laboratory and numerical investigations. Laboratory and field experiments have demonstrated the four core methodologies for producing natural gas hydrates from geologic formations: 1) depressurization, 2) thermal stimulation, 3) inhibitor injection, and 4) guest molecule exchange. Converting these methodologies into viable commercial technologies remains challenging, either from an economic or technical perspective. This project was largely focused with the technical challenges associated with the guest molecule exchange method, which is often referred to as gas swapping. Previous research by PNNL had shown that gas swapping with pure CO 2 was not feasible, as first originally thought, principally due to the formation of secondary hydrates, which clogged or reduced the effective permeability of the hydrate-bearing formation. This research was directed at discovering the potential for using mixtures of gases to affect the gas swapping methodology at commercial scales. The Ignik Sikumi Gas Hydrate Field Trial demonstrated the injection of a N 2 -CO 2 gas mixture into a natural gas hydrate bearing layer, and exchange behavior with the CH 4 hydrate former or guest molecules. The original concept behind the use of a N 2 -CO 2 was to maintain gas conditions at the reservoir state. Pure CO 2 would have existed under supercritical conditions, with an associated density closer to a liquid than gas. One of the key outcomes from this research project has been the discovery, through laboratory experiments and numerical simulation, that gas mixtures, especially those with components having different gas hydrate equilibria conditions provide a control option for the guest molecule exchange methodology. For example, the dissociation or formation of hydrate could be controlled by adjusting the composition of the gas mixture. This research project was dynamic in that the discoveries during each budget period would set the course of research during successive budget periods. Therefore, this report is arranged in chronological order progressing through the five budget periods of the project.

03 NATURAL GAS↗
NASA NTRS1973

Unified Approach to the Biomechanics of Dental Implantology

The human need for safe and effective dental implants is well-recognized. Although many implant designs have been tested and are in use today, a large number have resulted in clinical failure. These failures appear to be due to biomechanical effects, as well as biocompatibility and surgical factors. A unified approach is proposed using multidisciplinary systems technology, for the study of the biomechanical interactions between dental implants and host tissues. The approach progresses from biomechanical modeling and analysis, supported by experimental investigations, through implant design development, clinical verification, and education of the dental practitioner. The result of the biomechanical modeling, analysis, and experimental phases would be the development of scientific design criteria for implants. Implant designs meeting these criteria would be generated, fabricated, and tested in animals. After design acceptance, these implants would be tested in humans, using efficient and safe surgical and restorative procedures. Finally, educational media and instructional courses would be developed for training dental practitioners in the use of the resulting implants.

Grenoble, D. E.↗
NASA NTRS1975

Verification of a landing dynamics computer program using Viking Lander data

An investigation was conducted to verify the accuracy of the Landing Dynamics Computer Program (LDCP) used to simulate the landing event of the Viking Lander (VL) on to the Martian surface. This verification was achieved by comparing the analytical data with results from a test program involving a dynamically scaled model of a VL configuration. A secondary objective of this study was to evaluate the sensitivity of the VL to initial rates and orientations, configuration modifications, and footpad friction.

Muraca, R. J.↗
NASA NTRS1977

Coupled dynamics analysis of wind energy systems

A qualitative description of all key elements of a complete wind energy system computer analysis code is presented. The analysis system addresses the coupled dynamics characteristics of wind energy systems, including the interactions of the rotor, tower, nacelle, power train, control system, and electrical network. The coupled dynamics are analyzed in both the frequency and time domain to provide the basic motions and loads data required for design, performance verification and operations analysis activities. Elements of the coupled analysis code were used to design and analyze candidate rotor articulation concepts. Fundamental results and conclusions derived from these studies are presented.

Hoffman, J. A.↗