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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 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Analysis of Solar Receiver Performance for Chemical-Looping Integration With a Concentrating Solar Thermal System

This paper introduces a chemical-looping configuration integrated with a concentrating solar thermal (CST) system. The CST system uses an array of mirrors to focus sunlight, and the concentrated solar flux is applied onto a solar receiver to collect and convert solar energy into thermal energy. The thermal energy then drives a thermal power cycle for electricity generation or provides an energy source to chemical processes for material or fuel production. Considerable interest in CST has been driven by power generation with its capability to store thermal energy for continuous electricity supply or peak shaving. However, CST systems have other potential to convert solar energy into fuel or support thermochemical processes. The chemical-looping configuration integrated with the CST system can be a platform for implementing various solar-thermochemical processes. The chemical-looping configuration integrated with a CST system has potential applications for thermochemical energy storage and solar thermochemical hydrogen production. To use the solar energy efficiently and effectively, a high-temperature reactor receiver is a key component in the chemical-looping system. This paper shows a novel planar-cavity receiver design and its performance analyzed by solar-tracing and thermal-modeling methods for solar integration in a CST system.

14 SOLAR ENERGY↗
DOE OSTI2020

Plasma Processing of SRF Cavities for the Next Generation of Particle Accelerators

What are the major goals of the project? Goal 1: Optimize interactively processing of the single-cell cavity by combining plasma treatment and vertical cold bath testing. Continue using single cell cavity as the test bed for new applications. Goal 2: Work on upgrading the plasma etching technology for multi-cell SRF cavities. Goal 3: Develop and adapt discharge configurations to critical cavity regions including the electron beam weld (EBW) and iris areas. Goal 4: Develop tailored methods to prepare surface properties for a specific function prior to any additional modification, such as (but not limited to) surface passivation in preparation of other superconducting materials and structures.

43 PARTICLE ACCELERATORS↗
NASA NTRS1972

Development and verification of design methods for ducts in a space nuclear shield

A practical method for computing the effectiveness of a space nuclear shield perforated by small tubing and cavities is reported. Performed calculations use solutions for a two dimensional transport code and evaluate perturbations of that solution using last flight estimates and other kernel integration techniques. In general, perturbations are viewed as a change in source strength of scattered radiation and a change in attenuation properties of the region.

Cerbone, R. J.↗
NASA NTRS1978

Investigation of direct solar-to-microwave energy conversion techniques

Identification of alternative methods of producing microwave energy from solar radiation for purposes of directing power to the Earth from space is investigated. Specifically, methods of conversion of optical radiation into microwave radiation by the most direct means are investigated. Approaches based on demonstrated device functioning and basic phenomenologies are developed. There is no system concept developed, that is competitive with current baseline concepts. The most direct methods of conversion appear to require an initial step of production of coherent laser radiation. Other methods generally require production of electron streams for use in solid-state or cavity-oscillator systems. Further development is suggested to be worthwhile for suggested devices and on concepts utilizing a free-electron stream for the intraspace station power transport mechanism.

Chatterton, N. E.↗
NASA NTRS1982

Method for repair of thin glass coatings

A method of repairing cracks or damaged areas in glass, in particular, glass coatings provided on tile. The method includes removing the damaged area using a high speed diamond burr drilling out a cavity that extends slightly into the base material of the tile. All loose material is then cleaned from the drilled out cavity and the cavity is filled adjacent the upper surface of the coating with a filler material including chopped silica fibers mixed with a binder. The filler material is packed into the cavity and a repair coating is applied by means of a brush or sprayed thereover. The repair includes borosilicate suspended in solution. Heat is applied at approximately 2100 F. for approximately five minutes for curing the coating, causing boron silicide particles of the coating to oxidize forming a very fluid boron-oxide rich glass which reacts with the other frits to form an impervious, highly refractory layer.

Holt, J. W.↗
NASA NTRS1983

Second-law efficiency of solar-thermal cavity receivers

Properly quantified performance of a solar-thermal cavity receiver must not only account for the energy gains and losses as dictated by the First Law of thermodynamics, but it must also account for the quality of that energy. However, energy quality can only be determined from the Second Law. An equation for the Second Law efficiency of a cavity receiver is derived from the definition of available energy, which is a thermodynamic property that measures the maximum amount of work obtainable when a system is allowed to come into unrestrained equilibrium with the surrounding environment. The fundamental concepts of the entropy and availability of radiation were explored from which a workable relationship among the reflected cone half-angle, the insolation, and the concentrator geometric characteristics was developed as part of the derivation of the Second Law efficiency. First and Second Law efficiencies were compared for data collected from two receivers that were designed for different purposes. A Second Law approach to quantifying the performance of a solar-thermal cavity receiver lends greater insight into the total performance than does the conventional First Law method.

Moynihan, P. I.↗
NASA NTRS1984

Microwave-enhanced thin-film deposition

The deposition of semiconducting and insulating thin films at low temperatures using microwave technology was explored. The method of plasma formations, selection of a power source, the design of the microwave plasma cavity, the microwave circuitry, impedance matching, plasma diagnostics, the deposition chamber and the vacuum system were studied.

Chitre, S.↗
NASA NTRS1991

CO2 laser preionisation

The final report for work done during the reporting period of January 25, 1990 to January 24, 1991 is presented. A literature survey was conducted to identify the required parameters for effective preionization in TEA CO2 lasers and the methods and techniques for characterizing preionizers are reviewed. A numerical model of the LP-140 cavity was used to determine the cause of the transverse mode stability improvement obtained when the cavity was lengthened. The measurement of the voltage and current discharge pulses on the LP-140 were obtained and their subsequent analysis resulted in an explanation for the low efficiency of the laser. An assortment of items relating to the development of high-voltage power supplies is also provided. A program for analyzing the frequency chirp data files obtained with the HP time and frequency analyzer is included. A program to calculate the theoretical LIMP chirp is also included and a comparison between experiment and theory is made. A program for calculating the CO2 linewidth and its dependence on gas composition and pressure is presented. The program also calculates the number of axial modes under the FWHM of the line for a given resonator length. A graphical plot of the results is plotted.

Spiers, Gary D.↗
NASA NTRS2014

Constraining the Structure of the Transition Disk HD 135344B (SAO 206462) by Simultaneous Modeling of Multiwavelength Gas and Dust Observations

Context: Constraining the gas and dust disk structure of transition disks, particularly in the inner dust cavity, is a crucial step toward understanding the link between them and planet formation. HD 135344B is an accreting (pre-)transition disk that displays the CO 4.7 micrometer emission extending tens of AU inside its 30 AU dust cavity. Aims: We constrain HD 135344B's disk structure from multi-instrument gas and dust observations. Methods: We used the dust radiative transfer code MCFOST and the thermochemical code ProDiMo to derive the disk structure from the simultaneous modeling of the spectral energy distribution (SED), VLT/CRIRES CO P(10) 4.75 Micrometers, Herschel/PACS [O(sub I)] 63 Micrometers, Spitzer/IRS, and JCMT CO-12 J = 3−2 spectra, VLTI/PIONIER H-band visibilities, and constraints from (sub-)mm continuum interferometry and near-IR imaging. Results: We found a disk model able to describe the current gas and dust observations simultaneously. This disk has the following structure. (1) To simultaneously reproduce the SED, the near-IR interferometry data, and the CO ro-vibrational emission, refractory grains (we suggest carbon) are present inside the silicate sublimation radius (0.08 is less than R less than 0.2 AU). (2) The dust cavity (R is less than 30 AU) is filled with gas, the surface density of the gas inside the cavity must increase with radius to fit the CO ro-vibrational line profile, a small gap of a few AU in the gas distribution is compatible with current data, and a large gap of tens of AU in the gas does not appear likely. (4) The gas-to-dust ratio inside the cavity is >100 to account for the 870 Micrometers continuum upper limit and the CO P(10) line flux. (5) The gas-to-dust ratio in the outer disk (30 is less than R less than 200 AU) is less than 10 to simultaneously describe the [O(sub I)] 63 Micrometers line flux and the CO P(10) line profile. (6) In the outer disk, most of the gas and dust mass should be located in the midplane, and a significant fraction of the dust should be in large grains. Conclusions: Simultaneous modeling of the gas and dust is required to break the model degeneracies and constrain the disk structure. An increasing gas surface density with radius in the inner cavity echoes the effect of a migrating Jovian planet in the disk structure. The low gas mass (a few Jupiter masses) throughout the HD 135344B disk supports the idea that it is an evolved disk that has already lost a large portion of its mass.

inner dust cavity↗
DOE OSTI2011

Pretreatment Apparent Diffusion Coefficient of the Primary Lesion Correlates With Local Failure in Head-and-Neck Cancer Treated With Chemoradiotherapy or Radiotherapy

Purpose: This study was performed to evaluate whether the apparent diffusion coefficient (ADC) of a primary lesion correlates with local failure in primary head-and-neck squamous cell carcinoma (HNSCC) treated with chemoradiotherapy or radiotherapy. Methods and Materials: We retrospectively studied 38 patients with primary HNSCC (12 oropharynx, 20 hypopharynx, 4 larynx, 2 oral cavity) treated with chemoradiotherapy or radiotherapy with radiation dose to gross tumor volume equal to or over 60 Gy and who underwent pretreatment magnetic resonance imaging, including diffusion-weighted imaging. Ten patients developed local failure during follow-up periods of 2.0 to 9.3 months, and the remaining 28 showed local control during follow-up periods of 10.5 to 31.7 months. The variables that could affect local failure (age, tumor volume, ADC, T stage, N stage, dose, treatment method, tumor location, and overall treatment time) were analyzed using logistic regression analyses for all 38 patients and for 17 patients with Stage T3 or T4 disease. Results: In univariate logistic analysis for all 38 cases, tumor volume, ADC, T stage, and treatment method showed significant (p < 0.05) associations with local failure. In multivariate analysis, ADC and T stage revealed significance (p < 0.01). In univariate logistic analysis for the 17 patients with Stage T3 or T4 disease, ADC and dose showed significant (p < 0.01) associations with local failure. In multivariate analysis, ADC alone showed significance (p < 0.05). Conclusions: The results suggest that pretreatment ADC, along with T stage, is a potential indicator of local failure in HNSCC treated with chemoradiotherapy or radiotherapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Ductal Carcinoma in Situ-The Influence of the Radiotherapy Boost on Local Control

Purpose: Local recurrence (LR) of ductal carcinoma in situ (DCIS) is reduced by whole-breast irradiation after breast-conserving surgery (BCS). However, the benefit of adding a radiotherapy boost to the surgical cavity for DCIS is unclear. We sought to determine the impact of the boost on LR in patients with DCIS treated at the McGill University Health Centre. Methods and Materials: A total of 220 consecutive cases of DCIS treated with BCS and radiotherapy between January 2000 and December 2006 were reviewed. Of the patients, 36% received a radiotherapy boost to the surgical cavity. Median follow-up was 46 months for the boost and no-boost groups. Kaplan-Meier survival analyses and Cox regression analyses were performed. Results: Compared with the no-boost group, patients in the boost group more frequently had positive and <0.1-cm margins (48% vs. 8%) (p < 0.0001) and more frequently were in higher-risk categories as defined by the Van Nuys Prognostic (VNP) index (p = 0.006). Despite being at higher risk for LR, none (0/79) of the patients who received a boost experienced LR, whereas 8 of 141 patients who did not receive a boost experienced an in-breast LR (log-rank p = 0.03). Univariate analysis of prognostic factors (age, tumor size, margin status, histological grade, necrosis, and VNP risk category) revealed only the presence of necrosis to significantly correlate with LR (log-rank p = 0.003). The whole-breast irradiation dose and fractionation schedule did not affect LR rate. Conclusions: Our results suggest that the use of a radiotherapy boost improves local control in DCIS and may outweigh the poor prognostic effect of necrosis.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Energy Saving Melting and Revert Reduction Technology (E-SMARRT): Mechanical Performance of Dies

As a net shape process, die casting is intrinsically efficient and improvements in energy efficiency are strongly dependent on design and process improvements that reduce scrap rates so that more of the total consumed energy goes into acceptable, usable castings. A casting that is distorted and fails to meet specified dimensional requirements is typically remelted but this still results in a decrease in process yield, lost productivity, and increased energy consumption. This work focuses on developing, and expanding the use of, computer modeling methods that can be used to improve the dimensional accuracy of die castings and produce die designs and machine/die setups that reduce rejection rates due to dimensional issues. A major factor contributing to the dimensional inaccuracy of the casting is the elastic deformations of the die cavity caused by the thermo mechanical loads the dies are subjected to during normal operation. Although thermal and die cavity filling simulation are widely used in the industry, structural modeling of the die, particularly for managing part distortion, is not yet widely practiced. This may be due in part to the need to have a thorough understanding of the physical phenomenon involved in die distortion and the mathematical theory employed in the numerical models to efficiently model the die distortion phenomenon. Therefore, two of the goals of this work are to assist in efforts to expand the use of structural modeling and related technologies in the die casting industry by 1) providing a detailed modeling guideline and tutorial for those interested in developing the necessary skills and capability and 2) by developing simple meta-models that capture the results and experience gained from several years of die distortion research and can be used to predict key distortion phenomena of relevance to a die caster with a minimum of background and without the need for simulations. These objectives were met. A detailed modeling tutorial was provided to NADCA for distribution to the industry. Power law based meta-models for predicting machine tie bar loading and for predicting maximum parting surface separation were successfully developed and tested against simulation results for a wide range of machines and experimental data. The models proved to be remarkably accurate, certainly well within the requirements for practical application. In addition to making die structural modeling more accessible, the work advanced the state-of-the-art by developing improved modeling of cavity pressure effects, which is typically modeled as a hydrostatic boundary condition, and performing a systematic analysis of the influence of ejector die design variables on die deflection and parting plane separation. This cavity pressure modeling objective met with less than complete success due to the limits of current finite element based fluid structure interaction analysis methods, but an improved representation of the casting/die interface was accomplished using a combination of solid and shell elements in the finite element model. This approximation enabled good prediction of final part distortion verified with a comprehensive evaluation of the dimensions of test castings produced with a design experiment. An extra deliverable of the experimental work was development of high temperature mechanical properties for the A380 die casting alloy. The ejector side design objective was met and the results were incorporated into the metamodels described above. This new technology was predicted to result in an average energy savings of 2.03 trillion BTU's/year over a 10 year period. Current (2011) annual energy saving estimates over a ten year period, based on commercial introduction in 2009, a market penetration of 70% by 2014 is 4.26 trillion BTU's/year by 2019. Along with these energy savings, reduction of scrap and improvement in casting yield will result in a reduction of the environmental emissions associated with the melting and pouring of the metal which will be saved as a result of this technology. The average annual estimate of CO2 reduction per year through 2020 is 0.085 Million Metric Tons of Carbon Equivalent (MM TCE).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2015

System and method for underwater radiography

A system for subsea imaging comprises a first plate having an inner surface, an outer surface, and a cavity formed in the inner surface. In addition, the system comprises a phosphor imaging plate disposed in the cavity. Further, the system comprises a second plate having an inner surface facing the inner surface of the first plate and an outer surface facing away from the outer surface of the first plate. Still further, the system comprises a seal member disposed between the inner surface of the first plate and the inner surface of the second plate. The seal member extends around the perimeter of the cavity and is configured to seal the phosphor imaging plate and the cavity from intrusion water.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS2013

Aerodynamic and Acoustic Flight Test Results for the Stratospheric Observatory for Infrared Astronomy

As part of the Stratospheric Observatory for Infrared Astronomy (SOFIA) program, a 747SP airplane was modified to carry a 2.5 meter telescope in the aft section of the fuselage. The resulting airborne observatory allows for observations above 99 percent of the water vapor in the atmosphere. The open cavity created by the modifications had the potential to significantly affect the airplane in the areas of aerodynamics and acoustics. Several series of flight tests were conducted to clear the airplanes operating envelope for astronomical observations, planned to be performed between the altitudes of 39,000 feet and 45,000 feet. The flight tests were successfully completed. Cavity acoustics were below design limits, and the overall acoustic characteristics of the cavity were better than expected. The modification did have some effects on the stability and control of the airplane, but these effects were not significant. Airplane air data systems were not affected by the modifications. This paper describes the methods used to examine the aerodynamics and acoustic data from the flight tests and provides a discussion of the flight test results in the areas of cavity acoustics, stability and control, and air data.

SOFIA↗
DOE OSTI2011

Deformable Image Registration of Liver With Consideration of Lung Sliding Motion

Purpose: A feature based deformable registration model with sliding transformation was developed in the upper abdominal region for liver cancer. Methods: A two-step thin-plate spline (bi-TPS) algorithm was implemented to deformably register the liver organ. The first TPS registration was performed to exclusively quantify the sliding displacement component. A manual segmentation of the thoracic and abdominal cavity was performed as a priori knowledge. Tissue feature points were automatically identified inside the segmented contour on the images. The scale invariant feature transform method was utilized to match feature points that served as landmarks for the subsequent TPS registration to derive the sliding displacement vector field. To a good approximation, only motion along superior/inferior (SI) direction of voxels on each slice was averaged to obtain the sliding displacement for each slice. A second TPS transformation, as the last step, was carried out to obtain the local deformation field. Manual identification of bifurcation on liver, together with the manual segmentation of liver organ, was employed as a ''ground truth'' for assessing the algorithm's performance. Results: The proposed two-step TPS was assessed with six liver patients. The average error of liver bifurcation between manual identification and calculation for these patients was less than 1.8 mm. The residual errors between manual contour and propagated contour of liver organ using the algorithm fell in the range between 2.1 and 2.8 mm. An index of Dice similarity coefficient (DSC) between manual contour and calculated contour for liver tumor was 93.6% compared with 71.2% from the conventional TPS calculation. Conclusions: A high accuracy ({approx}2 mm) of the two-step feature based TPS registration algorithm was achievable for registering the liver organ. The discontinuous motion in the upper abdominal region was properly taken into consideration. Clinical implementation of the algorithm will find broad application in radiation therapy of liver cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗