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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Advanced MHD Algorithm for Solar and Space Science: lst Year Semi Annual Progress Report

We report progress for the development of MH4D for the first and second quarters of FY2004, December 29, 2002 - June 6, 2003. The present version of MH4D can now solve the full viscous and resistive MHD equations using either an explicit or a semi-implicit time advancement algorithm. In this report we describe progress in the following areas. During the two last quarters we have presented poster at the EGS-AGU-EUG Joint Assembly in Nice, France, April 6-11, 2003, and a poster at the 2003 International Sherwood Theory Conference in Corpus Christi, Texas, April 28-30 2003. In the area of code development, we have implemented the MHD equations and the semi-implicit algorithm. The new features have been tested.

Schnack, Dalton D.↗
NASA NTRS2003

Improvement in Geoid Models for Ocean Circulation Studies

At wavelengths of 500 km and longer, the GRACE GGM01 Model produces a significantly better marine geoid than any previous model. This conclusion follows from evaluating the geostrophic currents determined by combining the model with a mean sea surface from altimetry. The agreement with currents computed from a traditional hydrographic map is very close, which suggests that one of the primary missions of the TOPEX/POSEIDON mission, to determine the absolute dynamic ocean topography, may soon be met. This solution has been made available to the public at http://www.csr.utexs.edu/grace/gravity. The results reported in this paper have been presented at the 2003 EGS-AGU-EUG Joint Assembly. Two articles are currently being prepared for Geophysical Research Letters to summarize these results.

Tapley, Byron D.↗
NASA NTRS2014

Infrared Contrast Analysis Technique for Flash Thermography Nondestructive Evaluation

The paper deals with the infrared flash thermography inspection to detect and analyze delamination-like anomalies in nonmetallic materials. It provides information on an IR Contrast technique that involves extracting normalized contrast verses time evolutions from the flash thermography infrared video data. The paper provides the analytical model used in the simulation of infrared image contrast. The contrast evolution simulation is achieved through calibration on measured contrast evolutions from many flat bottom holes in the subject material. The paper also provides formulas to calculate values of the thermal measurement features from the measured contrast evolution curve. Many thermal measurement features of the contrast evolution that relate to the anomaly characteristics are calculated. The measurement features and the contrast simulation are used to evaluate flash thermography inspection data in order to characterize the delamination-like anomalies. In addition, the contrast evolution prediction is matched to the measured anomaly contrast evolution to provide an assessment of the anomaly depth and width in terms of depth and diameter of the corresponding equivalent flat-bottom hole (EFBH) or equivalent uniform gap (EUG). The paper provides anomaly edge detection technique called the half-max technique which is also used to estimate width of an indication. The EFBH/EUG and half-max width estimations are used to assess anomaly size. The paper also provides some information on the "IR Contrast" software application, half-max technique and IR Contrast feature imaging application, which are based on models provided in this paper.

Koshti, Ajay↗
NASA NTRS2014

Flash Infrared Thermography Contrast Data Analysis Technique

This paper provides information on an IR Contrast technique that involves extracting normalized contrast versus time evolutions from the flash thermography inspection infrared video data. The analysis calculates thermal measurement features from the contrast evolution. In addition, simulation of the contrast evolution is achieved through calibration on measured contrast evolutions from many flat-bottom holes in the subject material. The measurement features and the contrast simulation are used to evaluate flash thermography data in order to characterize delamination-like anomalies. The thermal measurement features relate to the anomaly characteristics. The contrast evolution simulation is matched to the measured contrast evolution over an anomaly to provide an assessment of the anomaly depth and width which correspond to the depth and diameter of the equivalent flat-bottom hole (EFBH) similar to that used as input to the simulation. A similar analysis, in terms of diameter and depth of an equivalent uniform gap (EUG) providing a best match with the measured contrast evolution, is also provided. An edge detection technique called the half-max is used to measure width and length of the anomaly. Results of the half-max width and the EFBH/EUG diameter are compared to evaluate the anomaly. The information provided here is geared towards explaining the IR Contrast technique. Results from a limited amount of validation data on reinforced carbon-carbon (RCC) hardware are included in this paper.

Koshti, Ajay↗
NASA NTRS1989

Evolution Of Cenospheres

Microscopy reveals changes in structure during combustion. Experiments performed to trace evolution of structures of droplets of burning fuel oil. Many droplets burn incompletely, forming cenospheres. Knowledge of structure at various stages of combustion process contributes to efforts to design equipment to burn cenospheres.

Kwack, Eug Y.↗
NASA NTRS1989

Whistle Gauge Measures Flow And Temperature

Simple, rugged gauge used to measure speed of flow and temperature of steam or other gas flowing through pipes of arbitrary diameter, from 1 to 28 in. or larger. Specially designed, instrumented whistle - has no moving parts, small, nonobstruction, operates at high temperature and pressure, and cleans itself. Does not operate at zero flow, but at moderate flows (tens of meters per second) generates intense sound for use in measurements. Consists of slanted ring groove of depth D and pressure taps in wall of pipe carrying flow to be measured. Resonant wavelength of sound generated by ring groove depends primarily on size and shape of groove and approximately equal to 4D.

Shakkottai, Parthasarathy↗
NASA NTRS1990

Flows In Model Human Femoral Arteries

Flow is visualized with dye traces, and pressure measurements made. Report describes experimental study of flow in models of human femoral artery. Conducted to examine effect of slight curvature of artery on flow paths and distribution of pressure.

Back, Lloyd H.↗
NASA NTRS1990

Lignin Sensor Based On Flash-Pyrolysis Mass Spectrometry

New lignin sensor takes only few minutes to measure lignin content of specimen of wood, pulp, paper, or similar material. Includes flash pyrolizer and ion-trap detector that acts as mass spectrometer. Apparatus measures amount of molecular fragments of lignin in pyrolysis products of samples. Helpful in controlling digestors in paper mills to maintain required lignin content, and also in bleaching plants, where good control of bleaching becomes possible if quick determination of lignin content made.

Kwack, Eug Y.↗
NASA NTRS1990

Acoustic Humidity Sensor

Industrial humidity sensor measures volume fraction of water in air via its effect on speed of sound. Only portion of sensor exposed to sensed atmosphere is pair of stainless-steel tubes, one containing dry air and other containing moist air. Counters measure intervals between reflected pulses. Sensor rugged enough for use in harsh environments like those used to control drying of paper in paper mills, where most humidity sensors do not survive.

Shakkottai, Parthasarathy↗
NASA NTRS1992

Acoustic Device Would Measure Density Of Gas

Proposed acoustic sensor measures density of flowing gas or mixture of gases. Constructed in variety of configurations for use in monitoring industrial processes. Basic configuration, sensor comprises narrow tube closed at one end and open at other, sound transmitter located in closed end, and microphone located part way along tube. Entire sensor, or at least open end of tube, placed inside pipe or vessel containing gas, density of which measured. Transducer produces constant-velocity-amplitude sound waves at frequency lower than fundamental resonant frequency of tube.

Shakkottai, Parthasarathy↗
NASA NTRS1993

Experiments On Flow In A Coronary Artery

Report describes experiments on simulated flow of blood in atherosclerotic human coronary artery. Experiments performed on polyurethane cast made from S-shaped coronary artery of cadaver. Sucrose solution with viscosity of blood pumped through cast at physiologically realistic rates, and flow made pulsatile by mechanism alternately compressing and releasing elastic tube just upstream of cast.

Back, Lloyd H.↗
NASA NTRS1992

Acoustic device and method for measuring gas densities

Density measurements can be made in a gas contained in a flow through enclosure by measuring the sound pressure level at a receiver or microphone located near a dipole sound source which is driven at constant velocity amplitude at low frequencies. Analytical results, which are provided in terms of geometrical parameters, wave numbers, and sound source type for systems of this invention, agree well with published data. The relatively simple designs feature a transmitter transducer at the closed end of a small tube and a receiver transducer on the circumference of the small tube located a small distance away from the transmitter. The transmitter should be a dipole operated at low frequency with the kL value preferable less that about 0.3.

Shakkottai, Parthasarathy↗
NASA NTRS2005

Terrestrial Planet Finder Coronagraph Observatory summary

Creating an optical space telescope observatory capable of detecting and characterizing light from extra-solar terrestrial planets poses technical challenges related to extreme wavefront stability. The Terrestrial Planet Finder Coronagraph design team has been developing an observatory based on trade studies, modeling and analysis that has guided us towards design choices to enable this challenging mission. This paper will describe the current flight baseline design of the observatory and the trade studies that have been performed. The modeling and analysis of this design will be described including predicted performance and the tasks yet to be done.

space↗
NASA NTRS2006

Demonstration of spectral calibration for stellar interferometry

A breadboard is under development to demonstrate the calibration of spectral errors in microarcsecond stellar interferometers. Analysis shows that thermally and mechanically stable hardware in addition to careful optical design can reduce the wavelength dependent error to tens of nanometers. Calibration of the hardware can further reduce the error to the level of picometers. The results of thermal, mechanical and optical analysis supporting the breadboard design will be shown.

spectral calibration↗
NASA NTRS2004

Structural Modeling for the Terrestrial Planet Finder Mission

We present the most recent propulsion requirements for the Laser Interferometer Space Antenna (LISA) Mission and describe potential microth ruster technology that can meet these requirements. LISA consists of three spacecraft in heliocentric orbits, forming a triangle with 5x l o6 km sides that are the arms of three Michelson-type interferometers. Reflective proof masses provide the reference surfaces at the end of the interferometer arms as part of the Gravitational Reference Senso r (GRS) designed to detect gravitational waves. The microthrust propu lsion system will be part of the Disturbance Reduction System (DRS), which is responsible for maintaining each spacecraft position within approximately 10 nm around the proof masses. To provide the necessary sensitivity, the GRS must not experience spurious accelerations > 10 (exp -15) m/s(exp 2)# Hz (exp -1/2) in the 0.1 mHz to 1 Hz bandwidth, requiring precision formation flying and drag-free operation of the L ISA spacecraft. This leads to the following microthruster performance requirements: a thrust range of 2-30 microN, a thrust resolution < O .1 micro N, and thrust noise <0.1 micro N Hz (exp -1/2) over the LISA measurement bandwidth. The microthruster must provide this performanc e for 5 years continuously, contain 10 years worth of propellant, and not disrupt the science measurements. Potential microthruster techno logies include Colloid, Field Emission Electric Propulsion (FEEP), and precision cold gas microthrusters. Each of these technologies is des cribed in detail with focus on the NASA microthruster development of the Busek Colloid Micro-Newton Thruster (CMNT).

coronagraphs↗