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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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At least 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

An efficient and numerically stable procedure for generating sextic force fields in normal mode coordinates

In this paper, we outline a general, scalable, and black-box approach for calculating high-order strongly coupled force fields in rectilinear normal mode coordinates, based upon constructing low order expansions in curvilinear coordinates with naturally limited mode-mode coupling, and then transforming between coordinate sets analytically. The optimal balance between accuracy and efficiency is achieved by transforming from 3 mode representation quartic force fields in curvilinear normal mode coordinates to 4 mode representation sextic force fields in rectilinear normal modes. Using this reduced mode-representation strategy introduces an error of only 1 cm{sup −1} in fundamental frequencies, on average, across a sizable test set of molecules. We demonstrate that if it is feasible to generate an initial semi-quartic force field in curvilinear normal mode coordinates from ab initio data, then the subsequent coordinate transformation procedure will be relatively fast with modest memory demands. This procedure facilitates solving the nuclear vibrational problem, as all required integrals can be evaluated analytically. Our coordinate transformation code is implemented within the extensible PyPES library program package, at http://sourceforge.net/projects/pypes-lib-ext/.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Introducing GAMER: A fast and accurate method for ray-tracing galaxies using procedural noise

We developed a novel approach for fast and accurate ray-tracing of galaxies using procedural noise fields. Our method allows for efficient and realistic rendering of synthetic galaxy morphologies, where individual components such as the bulge, disk, stars, and dust can be synthesized in different wavelengths. These components follow empirically motivated overall intensity profiles but contain an additional procedural noise component that gives rise to complex natural patterns that mimic interstellar dust and star-forming regions. These patterns produce more realistic-looking galaxy images than using analytical expressions alone. The method is fully parallelized and creates accurate high- and low- resolution images that can be used, for example, in codes simulating strong and weak gravitational lensing. In addition to having a user-friendly graphical user interface, the C++ software package GAMER is easy to implement into an existing code.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Experimental calibration procedures for rotating Lorentz-force flowmeters

Rotating Lorentz-force flowmeters are a novel and useful technology with a range of applications in a variety of different industries. However, calibrating these flowmeters can be challenging, time-consuming, and expensive. In this paper, simple calibration procedures for rotating Lorentz-force flowmeters are presented. These procedures eliminate the need for expensive equipment, numerical modeling, redundant flowmeters, and system down-time. Finally, the calibration processes are explained in a step-by-step manner and compared to experimental results.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

The AME2016 atomic mass evaluation (I). Evaluation of input data; and adjustment procedures

This paper is the first of two articles (Part I and Part II) that presents the results of the new atomic mass evaluation, Ame2016. It includes complete information on the experimental input data (also including unused and rejected ones), as well as details on the evaluation procedures used to derive the tables of recommended values given in the second part. This article describes the evaluation philosophy and procedures that were implemented in the selection of specific nuclear reaction, decay and mass-spectrometric results. These input values were entered in the least-squares adjustment for determining the best values for the atomic masses and their uncertainties. Details of the calculation and particularities of the Ame are then described. All accepted and rejected data, including outweighted ones, are presented in a tabular format and compared with the adjusted values obtained using the least-squares fit analysis. Differences with the previous Ame2012 evaluation are discussed and specific information is presented for several cases that may be of interest to Ame users. The second Ame2016 article gives a table with the recommended values of atomic masses, as well as tables and graphs of derived quantities, along with the list of references used in both the Ame2016 and the Nubase2016 evaluations (the first paper in this issue). Amdc: http://amdc.impcas.ac.cn/

Ame↗
DOE OSTI2022

ATLAS ITk strip sensor quality control procedures and testing site qualification

Abstract The high-luminosity upgrade of the Large Hadron Collider, scheduled to become operational in 2029, requires the replacement of the ATLAS Inner Detector with a new all-silicon Inner Tracker. Radiation hard n + -in-p micro-strip silicon sensors were developed by the ATLAS Inner Tracker strip collaboration and are produced by Hamamatsu Photonics K.K. Production of the total amount of 22000 strip sensors has started in 2020 and will continue until 2025. The ATLAS strip sensor collaboration has the responsibility to monitor the quality of the fabricated devices by performing detailed measurements of individual sensor characteristics and by comparing the obtained results with the tests done by the manufacturer. Dedicated Quality Control procedures were developed to check whether the delivered large-format sensors adhere to the ATLAS specifications. The institutes performing the Quality Control testing of the pre-production and production ATLAS ITk strip sensors had to initially be qualified for multiple high-throughput tests by successfully completing the Site Qualification process. The Quality Control procedures and the qualification process are described in this paper.

Instruments & Instrumentation↗
DOE OSTI2018

Standardized protocols and procedures can precisely and accurately quantify non-structural carbohydrates

Non-structural carbohydrates (NSCs), the stored products of photosynthesis, building blocks for growth, and fuel for respiration, are central to plant metabolism, but their measurement is challenging. Differences in methods and procedures among laboratories can cause results to vary widely, limiting our ability to integrate and generalize patterns in plant C balance among studies. A recent assessment found that NSC concentrations measured for a common set of samples can vary by an order of magnitude, but sources for this variability were unclear. We measured a common set of nine plant material types, and two synthetic samples with known NSC concentrations, using a common protocol for sugar extraction and starch digestion, and three different sugar quantification methods (ion chromatography, enzyme, acid) in six laboratories. We also tested how sample handling, extraction solvent, and centralizing parts of the procedure in one laboratory affected results. NSC concentrations measured for synthetic samples were within about 11.5% of known values for all three methods. However, differences among quantification methods were the largest source of variation in NSC measurements for natural plant samples because the three methods quantify different NSCs. The enzyme method quantified only glucose, fructose, and sucrose, with ion chromatography we additionally quantified galactose, while the acid method quantified a large range of mono- and oligosaccharides. For some natural samples, acid method quantification doubled sugar relative to the other methods, demonstrating that trees allocate C to a range of sugar molecules. Sample handling had little effect on measurements, while ethanol sugar extraction improved accuracy over water extraction. Our results demonstrate that reasonable accuracy of NSC measurements can be achieved when different methods are used, as long as protocols are robust and standardized. Thus, we provide detailed protocols for the extraction, digestion and quantification of NSCs in plant samples, which should improve the comparability of NSC measurements among laboratories.

Landhäusser, Simon M.↗
DOE OSTI2017

Procedures for cryogenic X-ray ptychographic imaging of biological samples

Biological sample-preparation procedures have been developed for imaging human chromosomes under cryogenic conditions. A new experimental setup, developed for imaging frozen samples using beamline I13 at Diamond Light Source, is described. This manuscript describes the equipment and experimental procedures as well as the authors' first ptychographic reconstructions using X-rays.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Self-Reference Procedure to Reduce Uncertainty in Module Calibration

This paper presents a composite measurement approach that capitalizes on complimentary strengths of 3 different test beds to significantly reduce uncertainty in I-V parameters for secondary module calibration. This approach addresses PV manufacturers' need for reduced uncertainty in the calibration modules that provide the basis for their module power ratings. This new method enables NREL to reduce uncertainty for secondary module calibration in commercial c-Si modules from +/-3.2% to +/-0.7% for I SC and from +/-3.3% to +/-1.1% for P MAX . This new module self-reference, or MSR procedure is based on the sensitivity of module voltage to temperature plus the uniformity of outdoor sunlight. By calibrating module V OC in thermal equilibrium on a flash simulator we provide an accurate gauge of junction temperature for subsequent measurements. By calibrating I SC outdoors in natural sunlight we enable the module to serve as its own reference device in setting the intensity of a continuous simulator, effectively eliminating the impact of spatial non-uniformity and spectral mismatch on the I-V measurement. These procedures significantly reduce measurement errors due to temperature uncertainty, spatial non-uniformity, and spectral mismatch.

14 SOLAR ENERGY↗
DOE OSTI2018

Artifact-Free Coring Procedures for Removing Samples from Photovoltaic Modules for Microscopic Analysis

An important step in producing more reliable and efficient photovoltaic modules is to establish a relationship between the microscopic properties of modules deployed in the field for many years and efficiency-related parameters. The first step in accomplishing this task is to be able to identify and remove small areas from these modules without causing any damage to these samples. In this work, we will describe two different procedures to core small areas of deployed and stressed solar panels produced with different materials (Si, CIGS, and CdTe), and we will prove that these processes did not damage the cored material. We will also show that the coring procedure changes for different types of photovoltaic modules.

14 SOLAR ENERGY↗
DOE OSTI2025

A Weakly Supervised Machine Learning Procedure for Magnet Quench Diagnostics

Voltage taps remain the standard and reliable diagnostic tool for detecting quenches in superconducting magnets. However, they identify a quench only at the time of voltage rise and do not provide information on earlier physical precursors. In this work, we investigate whether acoustic emission data can reveal precursor activity that occurs before conventional voltage detection using machine learning techniques. We introduce an event selection method and a weakly supervised machine learning procedure to learn data-driven criteria for identifying potential acoustic precursors to quenches. Two Convolutional Neural Network (CNN) architectures are trained: one on acoustic sensor events from our selection procedure and one on the Fast Fourier Transforms (FFTs) of these events. Both networks are trained iteratively using confidence-weighted loss functions to associate certain subsets of training data with a precursor label. We evaluate the performance of these models by examining the time distribution of events classified as potential precursors relative to the quench onset. Results indicate that the proposed approach can possibly distinguish acoustic emission events occurring closer to the quench from earlier acoustic activity during ramping, suggesting the potential for flagging quench precursors in acoustic data.

Khan, Maira [Fermilab] (ORCID:0009000891602387)↗
DOE OSTI2014

SU-E-I-42: Normalized Embryo/fetus Doses for Fluoroscopically Guided Pacemaker Implantation Procedures Calculated Using a Monte Carlo Technique

Purpose: It is well known that pacemaker implantation is sometimes needed in pregnant patients with symptomatic bradycardia. To our knowledge, there is no reported experience regarding radiation doses to the unborn child resulting from fluoroscopy during pacemaker implantation. The purpose of the current study was to develop a method for estimating embryo/fetus dose from fluoroscopically guided pacemaker implantation procedures performed on pregnant patients during all trimesters of gestation. Methods: The Monte Carlo N-Particle (MCNP) radiation transport code was employed in this study. Three mathematical anthropomorphic phantoms representing the average pregnant patient at the first, second and third trimesters of gestation were generated using Bodybuilder software (White Rock science, White Rock, NM). The normalized embryo/fetus dose from the posteroanterior (PA), the 30° left-anterior oblique (LAO) and the 30° right-anterior oblique (RAO) projections were calculated for a wide range of kVp (50–120 kVp) and total filtration values (2.5–9.0 mm Al). Results: The results consist of radiation doses normalized to a) entrance skin dose (ESD) and b) dose area product (DAP) so that the dose to the unborn child from any fluoroscopic technique and x-ray device used can be calculated. ESD normalized doses ranged from 0.008 (PA, first trimester) to 2.519 μGy/mGy (RAO, third trimester). DAP normalized doses ranged from 0.051 (PA, first trimester) to 12.852 μGy/Gycm2 (RAO, third trimester). Conclusion: Embryo/fetus doses from fluoroscopically guided pacemaker implantation procedures performed on pregnant patients during all stages of gestation can be estimated using the method developed in this study. This study was supported by the Greek Ministry of Education and Religious Affairs, General Secretariat for Research and Technology, Operational Program ‘Education and Lifelong Learning’, ARISTIA (Research project: CONCERT)

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

SU-E-T-615: Investigation of the Dosimetric Impact of Tandem Loading in the Treatment of Cervical Cancer for HDR Brachytherapy Procedures

Purpose: To quantify the dosimetric impact of the tandem loading in the treatment of cervical cancer for HDR brachytherapy procedures. Methods: Ten patients were evaluated, each of whom received 5 fractions of treatment. Tandem and ovoid sets were inserted into the uterine cavity based on institutional protocols and procedures. Following insertion and stabilization, CT image sets of 1.5mm slice thickness were acquired and sent to the Oncentra V4.3 Treatment Planning System. Critical structures such as the CTV, bladder, rectum, sigmoid, and bowel were contoured and a fractional dose of 5.5Gy was prescribed to Point A for each patient. Six different treatment plans were created for each fraction using varying tandem weightings; from 0.5 to 1.4 times that of the ovoids. Surface dose evaluation of various ovoid diameters, 2.0-3.5cm, at the vaginal fornices was also investigated. Results: Critical structures were evaluated based on varying dose and volume constraints, in particular the 2.0 cc volume recommendation cited by the gynecological GEC-ESTRO working group. Based on dose volume histogram evaluation, a reduction of dose to the critical structures was most often discovered when the tandem weighting was increased. CTV coverage showed little change as the tandem weighting was varied. Ovoid surface dose decreased by 50-65% as the tandem weighting increased. Conclusion: The advantage of 3D planning with HDR brachytherapy is the dose optimization for each individual treatment plan. This investigation shows that by utilizing large tandem weightings, 1.4 times greater than the ovoid, one can still achieve adequate coverage of the CTV and relatively low doses to the critical structures. In some cases, one would still have to optimize further per individual case. In addition, the ovoid surface dose was greatly decreased when large tandem weighting was utilized; especially for small ovoid diameters.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-P-44: A Direct Estimate of Peak Skin Dose for Interventional Fluoroscopy Procedures

Purpose: There is an increasing demand for medical physicist to calculate peak skin dose (PSD) for interventional fluoroscopy procedures. The dose information (Dose-Area-Product and Air Kerma) displayed in the console cannot directly be used for this purpose. Our clinical experience shows that the use of the existing methods may overestimate or underestimate PSD. This study attempts to develop a direct estimate of PSD from the displayed dose metrics. Methods: An anthropomorphic torso phantom was used for dose measurements for a common fluoroscopic procedure. Entrance skin doses were measured with a Piranha solid state point detector placed on the table surface below the torso phantom. An initial “reference dose rate” (RE) measurement was conducted by comparing the displayed dose rate (mGy/min) to the dose rate measured. The distance from table top to focal spot was taken as the reference distance (RD at the RE. Table height was then adjusted. The displayed air kerma and DAP were recorded and sent to three physicists to estimate PSD. An inverse square correction was applied to correct displayed air kerma at various table heights. The PSD estimated by physicists and the PSD by the proposed method were then compared with the measurements. The estimated DAPs were compared to displayed DAP readings (mGycm2). Results: The difference between estimated PSD by the proposed method and direct measurements was less than 5%. For the same set of data, the estimated PSD by each of three physicists is different from measurements by ±52%. The DAP calculated by the proposed method and displayed DAP readings in the console is less than 20% at various table heights. Conclusion: PSD may be simply estimated from displayed air kerma or DAP if the distance between table top and tube focal spot or if x-ray beam area on table top is available.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-J-10: Sliding Mode Control of a SMA Actuated Active Flexible Needle for Medical Procedures

Purpose: In medical interventional procedures such as brachytherapy, ablative therapies and biopsy precise steering and accurate placement of needles are very important for anatomical obstacle avoidance and accurate targeting. This study presents the efficacy of a sliding mode controller for Shape Memory Alloy (SMA) actuated flexible needle for medical procedures. Methods: Second order system dynamics of the SMA actuated active flexible needle was used for deriving the sliding mode control equations. Both proportional-integral-derivative (PID) and adaptive PID sliding mode control (APIDSMC) algorithms were developed and implemented. The flexible needle was attached at the end of a 6 DOF robotic system. Through LabView programming environment, the control commands were generated using the PID and APIDSMC algorithms. Experiments with artificial tissue mimicking phantom were performed to evaluate the performance of the controller. The actual needle tip position was obtained using an electromagnetic (EM) tracking sensor (Aurora, NDI, waterloo, Canada) at a sampling period of 1ms. During experiment, external disturbances were created applying force and thermal shock to investigate the robustness of the controllers. Results: The root mean square error (RMSE) values for APIDSMC and PID controllers were 0.75 mm and 0.92 mm, respectively, for sinusoidal reference input. In the presence of external disturbances, the APIDSMC controller showed much smoother and less overshooting response compared to that of the PID controller. Conclusion: Performance of the APIDSMC was superior to the PID controller. The APIDSMC was proved to be more effective controller in compensating the SMA uncertainties and external disturbances with clinically acceptable thresholds.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-T-250: What Does It Take to Correctly Assess the High Failure Modes of an Advanced Radiotherapy Procedure Such as Stereotactic Body Radiation Therapy?

Purpose: Assess the correct implementation of risk-based methodology of TG 100 to optimize quality management and patient safety procedures for Stereotactic Body Radiation Therapy. Methods: A detailed process map of SBRT treatment procedure was generated by a team of three physicists with varying clinical experience at our institution to assess the potential high-risk failure modes. The probabilities of occurrence (O), severity (S) and detectability (D) for potential failure mode in each step of the process map were assigned by these individuals independently on the scale from1 to 10. The risk priority numbers (RPN) were computed and analyzed. The highest 30 potential modes from each physicist’s analysis were then compared. Results: The RPN values assessed by the three physicists ranged from 30 to 300. The magnitudes of the RPN values from each physicist were different, and there was no concordance in the highest RPN values recorded by three physicists independently. The 10 highest RPN values belonged to sub steps of CT simulation, contouring and delivery in the SBRT process map. For these 10 highest RPN values, at least two physicists, irrespective of their length of experience had concordance but no general conclusions emerged. Conclusion: This study clearly shows that the risk-based assessment of a clinical process map requires great deal of preparation, group discussions, and participation by all stakeholders. One group albeit physicists cannot effectively implement risk-based methodology proposed by TG100. It should be a team effort in which the physicists can certainly play the leading role. This also corroborates TG100 recommendation that risk-based assessment of clinical processes is a multidisciplinary team effort.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-G-206-05: A Comparison of Head Phantoms Used for Dose Determination in Imaging Procedures

Purpose: To determine similarities and differences between various head phantoms that might be used for dose measurements in diagnostic imaging procedures. Methods: We chose four frequently used anthropomorphic head phantoms (SK-150, PBU-50, RS-240T and Alderson Rando), a computational patient phantom (Zubal) and the CTDI head phantom for comparison in our study. We did a CT scan of the head phantoms using the same protocol and compared their dimensions and CT numbers. The scan data was used to calculate dose values for each of the phantoms using EGSnrc Monte Carlo software. An .egsphant file was constructed to describe these phantoms using a Visual C++ program for DOSXYZnrc/EGSnrc simulation. The lens dose was calculated for a simulated CBCT scan using DOSXYZnrc/EGSnrc and the calculated doses were validated with measurements using Gafchromic film and an ionization chamber. Similar calculations and measurements were made for PA radiography to investigate the attenuation and backscatter differences between these phantoms. We used the Zubal phantom as the standard for comparison since it was developed based on a CT scan of a patient. Results: The lens dose for the Alderson Rando phantom is around 9% different than the Zubal phantom, while the lens dose for the PBU-50 phantom was about 50% higher, possibly because its skull thickness and the density of bone and soft tissue are lower than anthropometric values. The lens dose for the CTDI phantom is about 500% higher because of its totally different structure. The entrance dose profiles are similar for the five anthropomorphic phantoms, while that for the CTDI phantom was distinctly different. Conclusion: The CTDI and PBU-50 head phantoms have substantially larger lens dose estimates in CBCT. The other four head phantoms have similar entrance dose with backscatter hence should be preferred for dose measurement in imaging procedures of the head. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems Corp.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-G-TeP4-05: An Evaluation of a Low Dose Rate (LDR) Prostate Brachytherapy Procedure Using a Failure Modes and Effects Analysis (FMEA)

Purpose: The aim of the study is the application of a Failure Modes and Effects Analysis (FMEA) to access the risks for patients undergoing a Low Dose Rate (LDR) Prostate Brachytherapy Treatment. Methods: FMEA was applied to identify all the sub processes involved in the stages of identifying patient, source handling, treatment preparation, treatment delivery, and post treatment. These processes characterize the radiation treatment associated with LDR Prostate Brachytherapy. The potential failure modes together with their causes and effects were identified and ranked in order of their importance. Three indexes were assigned for each failure mode: the occurrence rating (O), the severity rating (S), and the detection rating (D). A ten-point scale was used to score each category, ten being the number indicating most severe, most frequent, and least detectable failure mode, respectively. The risk probability number (RPN) was calculated as a product of the three attributes: RPN = O X S x D. The analysis was carried out by a working group (WG) at UPMC. Results: The total of 56 failure modes were identified including 32 modes before the treatment, 13 modes during the treatment, and 11 modes after the treatment. In addition to the protocols already adopted in the clinical practice, the prioritized risk management will be implanted to the high risk procedures on the basis of RPN score. Conclusion: The effectiveness of the FMEA method was established. The FMEA methodology provides a structured and detailed assessment method for the risk analysis of the LDR Prostate Brachytherapy Procedure and can be applied to other radiation treatment modes.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

TU-D-209-06: Head and Neck Tissue Dose From X-Ray Scatter to Physicians Performing Cardiovascular Procedures

Purpose: The purpose of this work was to characterize the spatial distribution of scatter radiation to the head and neck of a physician performing an x-ray interventional procedure and assess brain, eye lens, and carotid artery dose. Methods: Radiographic x-ray beams were tuned to match the peak energy (56 to 106 keV) and HVL (3.5 to 6.5 mm Al) of x-ray scatter originating from a patient during a fluoroscopic procedure. The radiographic beam was directed upon a Rando phantom from an inferior-left location to mimic a typical patient-operator geometric relationship. A lead-equivalent protective garment was secured to the phantom. Direct exposure Gafchromic film (XRQA2) was placed between the transverse plane layers of the head and neck region of the phantom and exposed with 4 scatter-equivalent radiographic beams. A 3×3 cm{sup 2} film placed at the left collar of the phantom was used to monitor incident dose in the position of a radiation monitoring badge. The films were converted to 2D dose distribution maps using FilmQA Pro software and an Epson 11000-XL scanner. The 2D dose distributions maps were normalized by the left collar dose and the percent of left collar dose (%LCD) was calculated for select tissues. Results: The dose maps had high dynamic range (10{sub 4}) and spatial detail. Considering all transverse planes and 4 scatter beam qualities, the median %LCD values were: whole brain 8.5%, left brain 13%, right brain 5.4%, left eye lens 67%, right eye lens 25%, left carotid artery 72%, and right carotid artery 28%. Conclusion: Scatter radiation dose to an operator can be simulated using a tuned radiographic beam and used to expose a phantom and Gafchromic film, thereby creating detailed 2D dose distribution maps. This work facilitates individualized estimation of dose to select head and neck tissues based on an operator’s radiation monitoring badge value.

60 APPLIED LIFE SCIENCES↗