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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.
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Navigation and Guidance for the Mars Surveyor 1998 Mission
In December, 1998 and January 1999 NASA will launch two spacecraft to Mars as part of the overall Mars Exploration Program managed at JPL. One is an orbiter that will arrive at Mars in October of 1999 carrying a science payload for remote sensing.
Autonomous Guidance, Navigation, & Control (GN&C) for Next-Generation Missions
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Guidance Enhancements and Performance Assessments for the Mars Ascent Vehicle Spin-Stabilized Upper Stage Configuration
The objective of the Mars Sample Return (MSR) campaign is to return samples from the surface of Mars to Earth for research. As one element of the MSR campaign, the Mars Ascent Vehicle (MAV) is responsible for transporting the samples from the surface of Mars to a Low-Martian Orbit (LMO) for retrieval. Complete autonomy is required throughout ascent, and orbital insertion is constrained by tight dispersion boundaries. An unguided, spin-stabilized second stage for MAV has been selected over a guided upper-stage to drive mass savings and reduce overall MSR campaign mass risk, at the cost of reduced GNC capability. To address this design change, the MAV GNC team has derived a robust prediction algorithm, building on previous energy management schemes, that solves for a single inertial pointing direction solution for the spin-stabilized 2nd stage burn. Algorithm stability is explored that compared to previous versions of the algorithm. Also, a set of analytical partials was developed to study MAV’s dispersed orbital insertion performance with respect to MAV system uncertainties. These partials were verified through simulation analysis and prove useful for analytical insight into the dynamics of MAV during the 2nd stage maneuver.
Autonomous Navigation, Guidance, and Control Software in a Low SWaP Box
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Human Factors Guidance for Building a Computer-Based Procedures System: How to Give the Users Something They Actually Want.
Abstract not provided.
Optical Coherence Tomography Guidance during Peripheral Vascular Intervention
No abstract prepared.
Real-Time US-CT/MRI Image Fusion for Guidance of Thermal Ablation of Liver Tumors Undetectable with US: Results in 295 Cases
PurposeThis study was designed to assess feasibility of US-CT/MRI fusion-guided ablation in liver tumors undetectable with US.MethodsFrom 2002 to 2012, 295 tumors (162 HCCs and 133 metastases; mean diameter 1.3 ± 0.6 cm, range 0.5–2.5 cm) detectable on contrast-enhanced CT/MRI, but completely undetectable with unenhanced US and either totally undetectable or incompletely conspicuous with contrast-enhanced US (CEUS), were treated in 215 sessions using either internally cooled radiofrequency or microwave with standard ablation protocols, guided by an image fusion system (Virtual Navigation System, Esaote S.p.A., Genova, Italy) that combines US with CT/ MRI images. Correct targeting and successful ablation of tumor were verified after 24 hours with CT or MRI.ResultsA total of 282 of 295 (95.6 %) tumors were correctly targeted with successful ablation achieved in 266 of 295 (90.2 %). Sixteen of 295 (5.4 %) tumors were correctly targeted, but unsuccessfully ablated, and 13 of 295 (4.4 %) tumors were unsuccessfully ablated due to inaccurate targeting. There were no perioperative deaths. Major complications were observed in 2 of the 215 treatments sessions (0.9 %).ConclusionsReal-time virtual navigation system with US-CT/MRI fusion imaging is precise for targeting and achieving successful ablation of target tumors undetectable with US alone. Therefore, a larger population could benefit from ultrasound guided ablation procedures.
Real-Time US-{sup 18}FDG-PET/CT Image Fusion for Guidance of Thermal Ablation of {sup 18}FDG-PET-Positive Liver Metastases: The Added Value of Contrast Enhancement
Purpose: To assess the feasibility of US-{sup 18}FDG-PET/CT fusion-guided microwave ablation of liver metastases either poorly visible or totally undetectable with US, CEUS and CT, but visualized by PET imaging. Materials and Methods: Twenty-three patients with 58 liver metastases underwent microwave ablation guided by image fusion system that combines US with {sup 18}FDG-PET/CT images. In 28/58 tumors, {sup 18}FDG-PET/CT with contrast medium (PET/CECT) was used. The registration technical feasibility, registration time, rates of correct targeting, technical success at 24 h, final result at 1 year and complications were analyzed and compared between the PET/CT and PET/CECT groups. Results: Registration was successfully performed in all cases with a mean time of 7.8 + 1.7 min (mean + standard deviation), (4.6 + 1.5 min for PET/CECT group versus 10.9 + 1.8 min for PET/CT group, P < 0.01). In total, 46/58 (79.3%) tumors were correctly targeted, while 3/28 (10.7%) and 9/30 (30%) were incorrectly targeted in PET/CT and PET/CECT group, respectively (P < 0.05). Complete ablation was obtained at 24 h in 70.0% of cases (n = 40 tumors), 23/28 (82.1%) in the PET/CECT group and 17/30 (56.7%) in the PET/CT group (P < 0.037). Fourteen tumors underwent local retreatment (11 ablations, 2 with resection and 1 with stereotactic body radiation therapy), while 4 tumors could not be retreated because of distant disease progression and underwent systemic therapy. Finally, 54/58 (93.1%) tumors were completely treated at 1 year. One major complication occurred, a gastrointestinal hemorrhage which required surgical repair. Conclusions: Percutaneous ablation of {sup 18}FDG-PET-positive liver metastases using fusion imaging of real-time US and pre-acquired {sup 18}FDG-PET/CT images is feasible, safe and effective. Contrast-enhanced PET/CT improves overall ablation accuracy and shortens procedural duration time.
Percutaneous Lung Tumor Biopsy Under CBCT Guidance with PET-CT Fusion Imaging: Preliminary Experience
Purpose: The aim of this study is to evaluate the feasibility of percutaneous lung tumor biopsy under cone beam-computed tomography (CBCT) with PET-CT imaging fusion. Materials and Methods: Eleven patients (four women and seven men) underwent C-arm CBCT lung biopsy with PET-CT fusion imaging. A preprocedural PET-CT scan was manually fused with procedural CBCT based on anatomical landmarks; using real-time fluoroscopy, the coregistered PET-CT and CBCT images were overlaid to guide the needle trajectory. Technical success, accuracy, sensibility and specificity were evaluated. Mean total procedure time and time required for image elaboration were recorded. Results: Technical success, diagnostic accuracy, sensitivity and specificity were 100%. The mean procedure time was 38 min. The average time of PET-CT/CBCT image fusion elaboration was 3.53 min for planning and 3.42 min for needle positioning check. Conclusion: CBCT-guided percutaneous lung biopsy with PET-CT fusion imaging is a feasible and effective procedure, with the potential to further improve diagnostic yield by targeting the most metabolically active portion of a lesion, whether it is morphologically altered or normal.
Impact of image guidance on toxicity and tumour outcome in moderately hypofractionated external-beam radiotherapy for prostate cancer
To report toxicity and efficacy outcome of moderately hypofractionated image-guided external-beam radiotherapy in a large series of patients treated for prostate cancer (PCa). Between 10/2006 and 12/2015, 572 T1-T3N0M0 PCa patients received 70.2 Gy in 26 fractions at 2.7 Gy/fraction: 344 patients (60%) with three-dimensional conformal radiotherapy (3D-CRT) and 228 (40%) with intensity-modulated radiotherapy (IMRT). Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria and Houston definition (nadir + 2) were used for toxicity and biochemical failure evaluation, respectively. Median age was 74 years (interquartile range 69–77). Compared with 3D-CRT, in IMRT group more high-risk patients (29% vs 18%; P = 0.002) and more high-volume target (75% vs 60%; P < 0.001) were included. Acute gastro-intestinal (GI) toxicity G > 1 were registered in 8% and in 11% IMRT and 3D-CRT patients, respectively, whereas late GI G > 1 were observed in 2% and 16% IMRT and 3D-CRT patients, respectively. Acute genito-urinary (GU) toxicity G > 1 were registered in 26% and 40% IMRT and 3D-CRT patients, respectively, whereas late GU G > 1 occurred in 5% IMRT and 15% 3D-CRT patients. Multivariate proportional hazard Cox models confirmed significantly greater risk of late toxicity with 3D-CRT compared to IMRT for GU > 1 (P = 0.004) and for GI > 1 (P < 0.001). With a median 4-year follow-up, overall survival (OS), clinical progression-free survival (cPFS) and biochemical PFS (bPFS) for the whole series were 91%, 92% and 91%, respectively. cPFS and bPFS were significantly different by risk groups. Multivariate Cox models for bPFS and cPFS showed no difference between irradiation techniques and a significant impact of risk group and initial PSA. Moderately hypofractionated radiotherapy is a viable treatment option for localized PCa with excellent tumour control and satisfactory toxicity profile. IMRT seems associated with a reduction in toxicity, whereas tumour control was equal between IMRT and 3D-CRT patients and depended mainly on the risk category.
Myocardial perfusion imaging prior to coronary revascularization: From risk stratification to procedure guidance
No abstract prepared.
Guidelines in review: Comparison of ESC and AHA guidance for the diagnosis and management of infective endocarditis in adults. Are the differences clinically relevant? The European perspective
No abstract prepared.
Guidance to Design Grain Boundary Mobility Experiments with Molecular Dynamics and Phase-Field Modeling
Quantitative phase-field modeling can play an important role in designing experiments to measure the grain boundary (GB) mobility. In this work, molecular dynamics (MD) simulation is employed to determine the GB mobility using Cu bicrystals. Two grain configurations are considered: a shrinking circular grain and a half loop grain. The results obtained from the half loop configuration approaches asymptotically to that obtained from the circular configuration with increasing half loop width. We then verify the phase- field model by directly comparing to the MD simulation results, obtaining excellent agreement. Next, this phase-field model is used to predict the behavior in a common experimental setup that utilizes a half loop grain configuration in a bicrystal to measure the GB mobility. With a 3D simulation, we identify the two critical times within the experiments to reach an accurate value of the GB mobility. We use a series of 2D simulations to investigate the impact of the notch angle on these two critical times and we identify an angle of 60? as an optimal value. We also show that if the notch does not have a sharp tip, it may immobilize the GB migration indefinitely.
Performance analysis on novel thermodynamic cycle under the guidance of 3D construction method
Not Available
A survey on convex optimization for guidance and control of vehicular systems
Not Available
Neural architecture search via similarity adaptive guidance
Evolutionary neural network architecture search (ENAS) has attracted the attention of many experts due to its global optimization capabilities to automatically search for convolutional neural network architectures based on the target task. The current search space for ENAS is not to design a fully structured network, but to search for smaller cell architectures to reduce search costs. However, blind search strategies do not effectively utilize the potential experience of the population. In order to utilize the potential experience learned by the current population to guide the evolutionary search of the population, we propose a similarity guided neural network architecture search algorithm based on cell architecture, which utilizes the similarity between pairwise architectures in the population as empirical knowledge learned by the population. Our proposed algorithm provides a novel method for calculating architecture similarity, which calculates architecture similarity separately from the cell and macro-structure. Then we decouple the connections and operations in the cell and calculate connection and operation similarity separately. In addition, we propose adaptive similarity selection and binary tournament selection strategies to enhance the algorithm’s global and local search capabilities and effectively explore the search space. Finally, we design an improved single-point crossover operator to enhance the local search ability of the evolutionary operator. The experimental results show that SAGNAS is a competitive algorithm that achieves 97.44% and 81.60% in CIFAR10 and CIFAR100 with only 1.9 GPU-days spent.
Targeted multimodal nano-reporters for pre-procedural MRI and intra-operative image-guidance
Not Available