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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

SU-F-T-268: A Feasibility Study of Independent Dose Verification for Vero4DRT

Purpose: Vero4DRT (Mitsubishi Heavy Industries Ltd.) has been released for a few years. The treatment planning system (TPS) of Vero4DRT is dedicated, so the measurement is the only method of dose verification. There have been no reports of independent dose verification using Clarksonbased algorithm for Vero4DRT. An independent dose verification software program of the general-purpose linac using a modified Clarkson-based algorithm was modified for Vero4DRT. In this study, we evaluated the accuracy of independent dose verification program and the feasibility of the secondary check for Vero4DRT. Methods: iPlan (Brainlab AG) was used as the TPS. PencilBeam Convolution was used for dose calculation algorithm of IMRT and X-ray Voxel Monte Carlo was used for the others. Simple MU Analysis (SMU, Triangle Products, Japan) was used as the independent dose verification software program in which CT-based dose calculation was performed using a modified Clarkson-based algorithm. In this study, 120 patients’ treatment plans were collected in our institute. The treatments were performed using the conventional irradiation for lung and prostate, SBRT for lung and Step and shoot IMRT for prostate. Comparison in dose between the TPS and the SMU was done and confidence limits (CLs, Mean ± 2SD %) were compared to those from the general-purpose linac. Results: As the results of the CLs, the conventional irradiation (lung, prostate), SBRT (lung) and IMRT (prostate) show 2.2 ± 3.5% (CL of the general-purpose linac: 2.4 ± 5.3%), 1.1 ± 1.7% (−0.3 ± 2.0%), 4.8 ± 3.7% (5.4 ± 5.3%) and −0.5 ± 2.5% (−0.1 ± 3.6%), respectively. The CLs for Vero4DRT show similar results to that for the general-purpose linac. Conclusion: The independent dose verification for the new linac is clinically available as a secondary check and we performed the check with the similar tolerance level of the general-purpose linac. This research is partially supported by Japan Agency for Medical Research and Development (AMED)

60 APPLIED LIFE SCIENCES↗
NASA NTRS1972

Atmospheric rendezvous feasibility study

A study was carried out to determine the feasibility of using atmospheric rendezvous to increase the efficiency of space transportation and to determine the most effective implementation. It is concluded that atmospheric rendezvous is feasible and can be utilized in a space transportation system to reduce size of the orbiter vehicle, provide a powered landing with go-around capability for every mission, and achieve lateral range performance that exceeds requirements. A significantly lighter booster and reduced launch fuel requirements are additional benefits that can be realized with a system that includes a large subsonic airplane for recovery of the orbiter. Additional reduction in booster size is possible if the airplane is designed for recovery of the booster by towing. An airplane about the size of the C-5A is required.

Schaezler, A. D.↗
NASA NTRS1973

Feasibility study for rocket ozone measurements in the 50 to 80 km region using a chemiluminescent technique

A study has been conducted to determine the feasibility of increasing sensitivity for ozone detection. The detection technique employed is the chemiluminescent reaction of ozone with a rhodamine-B impregnated disk. Previously achieved sensitivities are required to be increased by a factor of about 20 to permit measurements at altitudes of 80 km. Sensitivity was increased by using a more sensitive photomultiplier tube, by increasing the gas velocity past the disk, by different disk preparation techniques, and by using reflective coatings in the disk chamber and on the uncoated side of the glass disk. Reflective coatings provided the largest sensitivity increase. The sum of all these changes was a sensitivity increased by an estimated factor of 70, more than sufficient to permit measurement of ambient ozone concentrations at altitudes of 80 km.

Goodman, P.↗
NASA NTRS1975

A feasibility study for measuring stratospheric turbulence using metrac positioning system

The feasibility of obtaining measurements of Lagrangian turbulence at stratospheric altitudes is demonstrated by using the METRAC System to track constant-level balloons. The basis for current estimates of diffusion coefficients are reviewed and it is pointed out that insufficient data is available upon which to base reliable estimates of vertical diffusion coefficients. It is concluded that diffusion coefficients could be directly obtained from Lagrangian turbulence measurements. The METRAC balloon tracking system is shown to possess the necessary precision in order to resolve the response of constant-level balloons to turbulence at stratospheric altitudes. A small sample of data recorded from a tropospheric tetroon flight tracked by the METRAC System is analyzed to obtain estimates of small-scale three-dimensional diffusion coefficients. It is recommended that this technique be employed to establish a climatology of diffusion coefficients and to ascertain the variation of these coefficients with altitude, season, and latitude.

Gage, K. S.↗
NASA NTRS1972

Feasibility study of inlet shock stability system of YF-12

The feasibility of self actuating bleed valves as a shock stabilization system in the inlet of the YF-12 is considered for vortex valves, slide valves, and poppet valves. Analytical estimation of valve performance indicates that only the slide and poppet valves located in the inlet cowl can meet the desired steady state stabilizing flows, and of the two the poppet valve is substantially faster in response to dynamic disturbances. The poppet valve is, therefore, selected as the best shock stability system for the YF-12 inlet.

Blausey, G. C.↗
NASA NTRS1979

Feasibility Study for a Numerical Aerodynamic Simulation Facility: Summary

The Ames Research Center of NASA is engaged in the development and investigation of numerical methods and computer technologies to be employed in conjunction with physical experiments, particularly utilizing wind tunnels in the furtherance of the field of aircraft and aerodynamic body design. Several studies, aimed primarily at the areas of development and production of extremely high-speed computing facilities, were conducted. The studies focused on evaluating the aspects of feasibility, reliability, costs, and practicability of designing, constructing, and bringing into effect production of a special-purpose system. An executive summary of the activities for this project is presented in this volume.

Lincoln, N. R.↗
NASA NTRS1984

Joined-wing research airplane feasibility study

The joined wing is a new type of aircraft configuration which employs tandem wings arranged to form diamond shapes in plan view and front view. Wind-tunnel tests and finite-element structural analyses have shown that the joined wing provides the following advantages over a comparable wing-plus-tail system; lighter weight and higher stiffness, higher span-efficiency factor, higher trimmed maximum lift coefficient, lower wave drag, plus built-in direct lift and direct sideforce control capability. To verify these advantages at full scale a manned research airplane is required. A study has therefore been performed of the feasibility of constructing such an airplane, using the fuselage and engines of the existing NAA AD-1 oblique-wing airplane. Cost and schedule constraints favored converting the AD-1 rather than constructing a totally new airframe. By removing the outboard wing panels the configuration can simulate wings joined at 60, 80, or 100 percent of span. For maximum versatility the aircraft has alternative control surfaces (such as ailerons and elevators on the front and/or rear wings), and a removeable canard to explore canard/joined-wing interactions at high-lift conditions. Design, performance, and flying qualities are discussed.

Wolkovitch, J.↗
NASA NTRSDate not supplied

Feasibility Study for Remote Psychoacoustic Testing of Human Response to Urban Air Mobility Vehicle Noise

NASA will remotely administer a psychoacoustic test in late summer of 2022 as the first of two phases of a cooperative Urban Air Mobility (UAM) vehicle noise human response study. This study relies on the cooperation of multiple government agencies, academia, and industry to assemble a wide range of UAM vehicle sounds. This database of sounds will be used to create a rich database of human response to UAM noise that would be challenging for a single organization to acquire. The development of the remote test method to study human response to aviation noise was prompted by the novel coronavirus pandemic. The feasibility portion of the study described in this work will demonstrate and refine the remote test method for use in the implementation phase. This paper details the method for remotely administering the psychoacoustic test and the sound stimuli to be used in the Feasibility Test. Comparisons of annoyance response data from previous in-person tests will be used to demonstrate the viability of the remote test method. The paper also describes an effort to determine if providing a contextual cue to test subjects influences the annoyance response.

UAM Vehicle Noise Human Response Study↗
NASA NTRSDate not supplied

Feasibility study for remote psychoacoustic testing of human response to urban air mobility vehicle noise

NASA will remotely administer a psychoacoustic test in late summer of 2022 as the first of two phases of a cooperative Urban Air Mobility (UAM) vehicle noise human response study. This study relies on the cooperation of multiple government agencies, academia, and industry to assemble a wide range of UAM vehicle sounds. This database of sounds will be used to create a rich database of human response to UAM noise that would be challenging for a single organization to acquire. The development of the remote test method to study human response to aviation noise was prompted by the novel coronavirus pandemic. The feasibility portion of the study described in this work will demonstrate and refine the remote test method for use in the implementation phase. This paper details the method for remotely administering the psychoacoustic test and the sound stimuli to be used in the Feasibility Test. Comparisons of annoyance response data from previous in-person tests will be used to demonstrate the viability of the remote test method. The paper also describes an effort to determine if providing a contextual cue to test subjects influences the annoyance response.

Remote psychoacoustic test↗
DOE OSTI2014

Beam dynamics in an ultra-low energy storage rings (review of existing facilities and feasibility studies for future experiments)

Storage rings operating at ultra-low energies and in particular electrostatic storage rings have proven to be invaluable tools for atomic and molecular physics. Due to the mass independence of the electrostatic rigidity, these machines are able to store a wide range of different particles, from light ions to heavy singly charged bio-molecules. However, earlier measurements showed strong limitations on beam intensity, fast decay of ion current, reduced life time etc. The nature of these effects was not fully understood. Also a large variety of experiments in future generation ultra-low energy storage and decelerator facilities including in-ring collision studies with a reaction microscope require a comprehensive investigation of the physical processes involved into the operation of such rings. In this paper, we present review of non-linear and long term beam dynamics studies on example of the ELISA, AD Recycler, TSR and USR rings using the computer codes BETACOOL, OPERA-3D and MAD-X. The results from simulations were benchmarked against experimental data of beam losses in the ELISA storage ring. We showed that decay of beam intensity in ultra-low energy rings is mainly caused by ion losses on ring aperture due to multiple scattering on residual gas. Beam is lost on ring aperture due to small ring acceptance. Rate of beam losses increases at high intensities because of the intra-beam scattering effect adds to vacuum losses. Detailed investigations into the ion kinetics under consideration of the effects from electron cooling and multiple scattering of the beam on a supersonic gas jet target have been carried out as well. The life time, equilibrium momentum spread and equilibrium lateral spread during collisions with this internal gas jet target were estimated. In addition, the results from experiments at the TSR ring, where low intensity beam of CF{sup +} ions at 93 keV/u has been shrunk to extremely small dimensions have been reproduced. Based on these simulations, conditions for stable ring operation with extremely low emittance beam are presented. Finally, results from studies into the interaction of ions with a gas jet target at 3–30 keV energy range are summarized.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

SU-E-T-419: Fabricating Cerrobend Grids with 3D Printing for Spatially Modulated Radiation Therapy: A Feasibility Study

Purpose: Grid therapy has promising applications in the radiation treatment of bulky and large tumors. However, research and applications of grid therapy is limited by the accessibility of the specialized blocks that produce the grid of pencil-like radiation beams. In this study, a Cerrobend grid block was fabricated using a 3D printing technique. Methods: A grid block mold was designed with divergent tubes following beam central rays. The mold was printed using a resin with the working temperature below 230 °C. The melted Cerrobend liquid at 120°oC was cast into the resin mold to yield a block with a thickness of 7.4 cm. The grid had a hexagonal pattern, with each pencil beam diameter of 1.4 cm at the iso-center plane; the distance between the beam centers was 2 cm. The dosimetric properties of the grid block were studied using radiographic film and small field dosimeters. Results: the grid block was fabricated to be mounted at the third accessory mount of a Siemens Oncor linear accelerator. Fabricating a grid block using 3D printing is similar to making cutouts for traditional radiotherapy photon blocks, with the difference being that the mold was created by a 3D printer rather than foam. In this study, the valley-to-peak ratio for a 6MV photon grid beam was 20% at dmax, and 30% at 10 cm depth, respectively. Conclusion: We have demonstrated a novel process for implementing grid radiotherapy using 3D printing techniques. Compared to existing approaches, our technique combines reduced cost, accessibility, and flexibility in customization with efficient delivery. This lays the groundwork for future studies to improve our understanding of the efficacy of grid therapy and apply it to improve cancer treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Numerical modelling of the flow in the resin infusion process on the REV scale: A feasibility study

The resin infusion process (RIP) has developed as a low cost method for manufacturing large fibre reinforced plastic parts. However, the process still presents some challenges to industry with regards to reliability and repeatability, resulting in expensive and inefficient trial and error development. In this paper, we show the implementation of 2D numerical models for the RIP using the open source simulator DuMu{sup X}. The idea of this study is to present a model which accounts for the interfacial forces coming from the capillary pressure on the so-called representative elementary volume (REV) scale. The model is described in detail and three different test cases — a constant and a tensorial permeability as well as a preform/Balsa domain — are investigated. The results show that the developed model is very applicable for the RIP for manufacturing of composite parts. The idea behind this study is to test the developed model for later use in a real application, in which the preform medium has numerous layers with different material properties.

42 ENGINEERING↗