Search NASA⌕ Search

SEARCH · Search NASA

Results for “five”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Lateral stability and control derivatives extracted from five early flights of the space shuttle Columbia

Flight data taken from the first five flights (STS-2, 3, 4, 5 and 9) of the Space Transportation System Shuttle Columbia during entry are analyzed to determine the Shuttle lateral aerodynamic characteristics. Maximum likelihood estimation is applied to data derived from accelerometer and rate gyro measurements and trajectory, meteorological and control surface data to estimate lateral-directional stability and control derivatives. The estimated parameters are compared across the five flights and to preflight predicted values.

Schiess, J. R.↗
NASA NTRS1986

Ultraviolet extinction toward five open clusters, and the accuracy of IUE extinction measurements

The UV extinction curves of 33 main-sequence B stars in five open clusters are presented and analyzed. An analytic fitting function is introduced which represents the observed curves and codifies the structure of the 2175 A extinction bump. A set of extinction parameters are also defined which describe the shape of the far-UV extinction. These data are first used to determine whether the extinction toward any of the clusters is uniform, i.e., whether it can be represented by a single curve for the cluster. This is accomplished by comparing the observed scatter of the far-UV extinction measurements toward a given cluster with that predicted by an error model. The extinction toward four of the five clusters is found to be uniform. The extinction data for those clusters with uniform extinction are then used to determine the observational uncertainties in other extinction parameters for which a priori error estimates cannot be made. With one exception, all of the parameters which describe the shapes of UV extinction curves differ significantly from cluster to cluster. The exception is the central position of the UV extinction bump, which has the same value for all of the cluster extinction curves. Applications and interpretation of the results are given elsewhere.

Massa, D.↗
NASA NTRS1987

Five year global dataset: NMC operational analyses (1978 to 1982)

This document describes procedures used in assembling a five year dataset (1978 to 1982) using NMC Operational Analysis data. These procedures entailed replacing missing and unacceptable data in order to arrive at a complete dataset that is continuous in time. In addition, a subjective assessment on the integrity of all data (both preliminary and final) is presented. Documentation on tapes comprising the Five Year Global Dataset is also included.

Straus, David↗
NASA NTRS1987

On the absence of young white dwarf companions to five technetium stars

A search for hot companions to five stars of type MS and S has been carried out using the IUE satellite. No hot companions were detected for the MS stars HR 85, 4647, 6702, and 8062, and the S star HR 8714. Limits on the luminosities of possible white dwarf companions provide lower limits of 2-5x10 to the 8th yr to the ages of any degenerate companions. All five stars exhibit strong Tc I lines, and the presence of technetium, with a half-life of 2.1x10 to the 5th yr, signifies recent nucleosynthesis. The limits on the ages of possible white dwarf companions that are equal to or greater than 1000 half-lives of Tc exclude the possibility that the s-process elemental enhancement seen in these MS and S stars resulted from mass transfer from a more highly evolved companion (as is probably the mechanism by which barium stars are created). These MS and S stars represent a sample of true thermally pulsing asymptotic giant-branch stars.

Smith, Verne V.↗
NASA NTRS1987

A five component electro-optical positioning system

The development of a five-component electrooptical positioning system for detecting the location of wind tunnel models within the test section is discussed. The system consists of three low power helium-neon lasers, five linear photodiode arrays, an assembly of optics that includes lenses and mirrors, and a signal conditioner. The system has been successfully installed and is currently in use at the 13-inch magnetic suspension and balance system (MSBS) at NASA Langley Research Center. Initially the system was developed as an auxiliary model position and attitude detecting system for that facility, but it has since been modified and interfaced with a PDP minicomputer to provide position feedback for the control loop.

Tcheng, Ping↗
NASA NTRS1991

Five degree-of-freedom control of an ultra-precision magnetically-suspended linear bearing

The authors constructed a high precision linear bearing. A 10.7 kg platen measuring 125 mm by 125 mm by 350 mm is suspended and controlled in five degrees of freedom by seven electromagnets. The position of the platen is measured by five capacitive probes which have nanometer resolution. The suspension acts as a linear bearing, allowing linear travel of 50 mm in the sixth degree of freedom. In the laboratory, this bearing system has demonstrated position stability of 5 nm peak-to-peak. This is believed to be the highest position stability yet demonstrated in a magnetic suspension system. Performance at this level confirms that magnetic suspensions can address motion control requirements at the nanometer level. The experimental effort associated with this linear bearing system is described. Major topics are the development of models for the suspension, implementation of control algorithms, and measurement of the actual bearing performance. Suggestions for the future improvement of the bearing system are given.

Trumper, David L.↗
NASA NTRS1990

H-alpha spectra of dynamic chromospheric processes in five well-observed X-ray flares

Simultaneous H-alpha and hard X-ray (HXR) spectra were obtained for five solar flares to determine the relationship of H-alpha profiles and the nonthermal part of the flare represented by the hard X-ray burst. All five flares exhibited impulsive-phase redshifted H-alpha in emission, which was temporarily and spatially associated with intense HXR emission and broad impulsive-phase H-alpha wings. A few small regions within two flares showed a blueshifted H-alpha emission which appeared only early in the impulsive phase and was temporally correlated with the HXR emission but not with broad H-alpha wings. Finally, there were both redshifted and blueshifted absorption spectra with properties fully consistent with those known for erupting and untwisting filaments.

Canfield, Richard C.↗
NASA NTRS1990

Flare heating and ionization of the low solar chromosphere. II - Observations of five solar flares

Two neutral Mg spectral lines formed in the temperature-minimum region and the low chromosphere, at 4571 and 5173 A, are used to quantify the changes in the atmospheric structure as a function of time during five solar flares. Eight proposed flare heating and ionization mechanisms and predictions of the effects of each on the temperature minimum region are discussed. Two Mg spectral observations made at the National Solar Observatory (Sacramento Peak), along with observations of hard and soft X-rays from the SMM and GOES satellites, are compared to the predictions of the eight proposed mechanisms. The initial effects in all five flares are consistent with backwarming by enhanced Balmer- and Paschen-continuum radiation originating in the upper chromosphere. Extended heating observed in two of the flares is most likely due to UV irradiation. In all cases heating by the dissipation of nonreversed electric currents, collisions with an electron or proton beam, irradiation by soft X-rays, and dissipation of Alfven waves are eliminated.

Metcalf, Thomas R.↗
NASA NTRS1990

Five basic steps to problem trending

Five basic steps to problem trending evolved from experience in trending problems on Space Shuttle hardware are discussed: extracting data; constructing a Pareto chart of all failure modes; constructing normalized subsystem, component, and failure-mode trend charts; identifying trend direction; and providing a summary assessment. The five-step method has been useful for identifying failure modes of concern, evaluating the effectiveness of corrective actions, and determining funding allocation.

Bombara, Elwood L.↗
NASA NTRS1992

Evaluation of the mechanical properties and damage tolerance of five new toughened matrix composite materials

Notched and unnotched tension and compression properties of quasi-isotropic laminates are presently evaluated, in conjunction with compression-after-impact (CAI) strengths, for the cases of five different carbon fiber-reinforced/toughened matrix composites. For a given impact energy, CAIs were dependent on impact velocities. When compared with other matrix-toughened materials, the five presently considered were more damage-tolerant than such aircraft primary structure composite systems as T300/5208.

Cano, Roberto J.↗
NASA NTRS1992

A search for microvariability in five OVV quasars

We present results of monitoring a sample of five OVV qausars in an effort to determine if these types of AGNs exhibit microvariability similar to that detected for BL Lacertae objects. Three of the five quasars investigated clearly exhibited microvariability. The timescales for the variations for both BL Lacertae objects and OVV quasars are similar which suggests that the radiation is generated in similar spatial volumes. These variations are consistent with the results of models which explain the observed microvariability as the result of excess emission produced by flares or hot spots randomly appearing and disappearing on the accretion disks around supermassive black holes.

Miller, H. R.↗
NASA NTRS1993

Structural design and analysis of a Mach zero to five turbo-ramjet system

The paper discusses the structural design and analysis of a Mach zero to five turbo-ramjet propulsion system for a Mach five waverider-derived cruise vehicle. The level of analysis detail necessary for a credible conceptual design is shown. The results of a finite-element failure mode sizing analysis for the engine primary structure is presented. The importance of engine/airframe integration is also discussed.

Spoth, Kevin A.↗
NASA NTRS1928

Characteristics of Five Propellers in Flight

This investigation was made for the purpose of determining the characteristics of five full-scale propellers in flight. The equipment consisted of five propellers in conjunction with a VE-7 airplane and a Wright E-2 engine. The propellers were of the same diameter and aspect ratio. Four of them differed uniformly in thickness and pitch and the fifth propeller was identical with one of the other four with exception of a change of the airfoil section. The propeller efficiencies measured in flight are found to be consistently lower than those obtained in model tests. It is probable that this is mainly a result of the higher tip speeds used in the full-scale tests. The results show also that because of differences in propeller deflections it is difficult to obtain accurate comparisons of propeller characteristics. From this it is concluded that for accurate comparisons it is necessary to know the propeller pitch angles under actual operating conditions. (author)

Crowley, J W , Jr↗
NASA NTRS1958

An Analysis of Pressure Studies and Experimental and Theoretical Downwash and Sidewash Behind Five Pointed-Tip Wings at Supersonic Speeds

Flow-angle and pressure surveys behind five, thin, pointed-tip wings of varying plan form have been made at Mach numbers 1.62 and 2.41. Schlieren studies at a Mach number 1.93 for the same five plan-form wings were made to illustrate the behavior of the vortex sheet. The surveys were conducted at 1.5, 3, and 4 root chords behind three triangular wings of 50 degree, 63 degree, and 72 degree leading-edge sweep angle, and behind the 50 degree triangular wing reversed. The flow behind a pointed-tip wing having a sweptback leading edge and a sweptforward trailing edge (both 50 degrees) was also surveyed. Experiment and one of the theoretical methods are compared for the reversed triangular wing and the pointed-tip wing with the 50 degree sweptback leading edge and sweptforward trailing edge.

Boatright, William B↗
NASA NTRS1993

Five biomedical experiments flown in an Earth orbiting laboratory: Lessons learned from developing these experiments on the first international microgravity mission from concept to landing

There are numerous problems associated with accommodating complex biological systems in microgravity in the flexible laboratory systems installed in the Orbiter cargo bay. This presentation will focus upon some of the lessons learned along the way from the University laboratory to the IML-1 Microgravity Laboratory. The First International Microgravity Laboratory (IML-1) mission contained a large number of specimens, including: 72 million nematodes, US-1; 3 billion yeast cells, US-2; 32 million mouse limb-bud cells, US-3; and 540 oat seeds (96 planted), FOTRAN. All five of the experiments had to undergo significant redevelopment effort in order to allow the investigator's ideas and objectives to be accommodated within the constraints of the IML-1 mission. Each of these experiments were proposed as unique entities rather than part of the mission, and many procedures had to be modified from the laboratory practice to meet IML-1 constraints. After a proposal is accepted by NASA for definition, an interactive process is begun between the Principal Investigator and the developer to ensure a maximum science return. The success of the five SLSPO-managed experiments was the result of successful completion of all preflight biological testing and hardware verification finalized at the KSC Life Sciences Support Facility housed in Hangar L. The ESTEC Biorack facility housed three U.S. experiments (US-1, US-2, and US-3). The U.S. Gravitational Plant Physiology Facility housed GTHRES and FOTRAN. The IML-1 mission (launched from KSC on 22 Jan. 1992, and landed at Dryden Flight Research Facility on 30 Jan. 1992) was an outstanding success--close to 100 percent of the prelaunch anticipated science return was achieved and, in some cases, greater than 100 percent was achieved (because of an extra mission day).

Winget, C. M.↗
NASA NTRS1994

An X-ray study of five supernova remnants in the Carina spiral arm

The ROSAT Position Sensitive Proportional Counter (PSPC) is used to perform an exploratory study of four fields in the Carina spiral arm containing five radio supernova remnants, only one of which has previously been studied in X-rays. We present upper limits for the detection in X-rays of G298.5 - 0.3, G298.6 - 0.0, and G299.0+0.2, and report a 4 sigma detection of G296.8-0.3. In addition, we present detailed spatial and spectral analysis of the bright X-ray remnant G296.1-0.7, which has previously been studied by both the Einstein IPC and EXOSAT LE/CMA. We detect relatively slight, but statistically significant, variations in the spectrum across the remnant via spatially resolved spectral fits and a study of the spatial variation of hardness ratios. In general, the spectrum is characteristic of a thermal plasma with kT about 0.2 keV and N(sub H) about 1.5 x 10(exp 21/sq. cm). The total X-ray emitting mass is estimated to be about 250 solar mass for an optically estimated distance of 4 kpc to the remnant. At this distance, the linear dimensions of the remnant are roughly 35 - 50 pc, implying an age on the order of 20,000 yr. Assuming that X-ray and radio brightnesses are related by SIGMA(sub R) proportional to SIGMA(exp 0.69)(sub X) and that the four radio remnants have X-ray spectral characteristics similar to G296.1-0.7, we find that the column densities to these sources must be several times 10(exp 22)/sq cm in order to explain their low X-ray count rates. This column density is considerably in excess of the X-ray fitted column density to G296.1-0.7, but is comparable to the total column densities in H I measured via the 21 cm line in the directions to all five remnants. This implies that G296.1 - 0.7 is at a significantly smaller distance than the other remnants.

Hwang, Una↗
NASA NTRS1995

Five-Channel Polychromator Head

Five-channel polychromator head samples Raman-scattering spectrum simultaneously at five wavelengths. Each channel consists of 1-mm fiber-optic cable that is individually translatable along dispersion axis of spectrometer to provide both flexibility and fine-tuning capability. Laser raman thermometer not thermometer in usual sense of word, but noncontact spectrometer that measures temperature indirectly in terms of relative intensities of selected Raman-scattering spectral lines.

Eskridge, Richard↗
NASA NTRS1998

Comparison of Five System Identification Algorithms for Rotorcraft Higher Harmonic Control

This report presents an analysis and performance comparison of five system identification algorithms. The methods are presented in the context of identifying a frequency-domain transfer matrix for the higher harmonic control (HHC) of helicopter vibration. The five system identification algorithms include three previously proposed methods: (1) the weighted-least- squares-error approach (in moving-block format), (2) the Kalman filter method, and (3) the least-mean-squares (LMS) filter method. In addition there are two new ones: (4) a generalized Kalman filter method and (5) a generalized LMS filter method. The generalized Kalman filter method and the generalized LMS filter method were derived as extensions of the classic methods to permit identification by using more than one measurement per identification cycle. Simulation results are presented for conditions ranging from the ideal case of a stationary transfer matrix and no measurement noise to the more complex cases involving both measurement noise and transfer-matrix variation. Both open-loop identification and closed- loop identification were simulated. Closed-loop mode identification was more challenging than open-loop identification because of the decreasing signal-to-noise ratio as the vibration became reduced. The closed-loop simulation considered both local-model identification, with measured vibration feedback and global-model identification with feedback of the identified uncontrolled vibration. The algorithms were evaluated in terms of their accuracy, stability, convergence properties, computation speeds, and relative ease of implementation.

Jacklin, Stephen A.↗