Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Mass measurement”

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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Characterization of microgravity effects on bone structure and strength using fractal analysis

The effect of micro-gravity on the musculoskeletal system has been well studied. Significant changes in bone and muscle have been shown after long term space flight. Similar changes have been demonstrated due to bed rest. Bone demineralization is particularly profound in weight bearing bones. Much of the current techniques to monitor bone condition use bone mass measurements. However, bone mass measurements are not reliable to distinguish Osteoporotic and Normal subjects. It has been shown that the overlap between normals and osteoporosis is found for all of the bone mass measurement technologies: single and dual photon absorptiometry, quantitative computed tomography and direct measurement of bone area/volume on biopsy as well as radiogrammetry. A similar discordance is noted in the fact that it has not been regularly possible to find the expected correlation between severity of osteoporosis and degree of bone loss. Structural parameters such as trabecular connectivity have been proposed as features for assessing bone conditions. In this report, we use fractal analysis to characterize bone structure. We show that the fractal dimension computed with MRI images and X-Ray images of the patella are the same. Preliminary experimental results show that the fractal dimension computed from MRI images of vertebrae of human subjects before bedrest is higher than during bedrest.

Acharya, Raj S.↗
NASA NTRS2011

Mass Balance of the West Antarctic Ice-Sheet from ICESat Measurements

Mass balance estimates for 2003-2008 are derived from ICESat laser altimetry and compared with estimates for 1992-2002 derived from ERS radar altimetry. The net mass balance of 3 drainage systems (Pine Island, Thwaites/Smith, and the coast of Marie Bryd) for 2003-2008 is a loss of 100 Gt/yr, which increased from a loss of 70 Gt/yr for the earlier period. The DS including the Bindschadler and MacAyeal ice streams draining into the Ross Ice Shelf has a mass gain of 11 Gt/yr for 2003-2008, compared to an earlier loss of 70 Gt/yr. The DS including the Whillans and Kamb ice streams has a mass gain of 12 Gt/yr, including a significant thickening on the upper part of the Kamb DS, compared to a earlier gain of 6 Gt/yr (includes interpolation for a large portion of the DS). The other two DS discharging into the Ronne Ice Shelf and the northern Ellsworth Coast have a mass gain of 39 Gt/yr, compared to a gain of 4 Gt/yr for the earlier period. Overall, the increased losses of 30 Gt/yr in the Pine Island, Thwaites/Smith, and the coast of Marie Bryd DSs are exceeded by increased gains of 59 Gt/yr in the other 4 DS. Overall, the mass loss from the West Antarctic ice sheet has decreased to 38 Gt/yr from the earlier loss of 67 Gt/yr, reducing the contribution to sea level rise to 0.11 mm/yr from 0.19 mm/yr

Zwally, H. Jay↗
DOE OSTI2021

Physical Parameters of the Multiplanet Systems HD 106315 and GJ 9827

HD 106315 and GJ 9827 are two bright, nearby stars that host multiple super-Earths and sub-Neptunes discovered by K2 that are well suited for atmospheric characterization. We refined the planets’ ephemerides through Spitzer transits, enabling accurate transit prediction required for future atmospheric characterization through transmission spectroscopy. Through a multiyear high-cadence observing campaign with Keck/High Resolution Echelle Spectrometer and Magellan/Planet Finder Spectrograph, we improved the planets’ mass measurements in anticipation of Hubble Space Telescope transmission spectroscopy. For GJ 9827, we modeled activity-induced radial velocity signals with a Gaussian process informed by the Calcium II H&K lines in order to more accurately model the effect of stellar noise on our data. We measured planet masses of M {sub b} = 4.87 ± 0.37 M {sub ⊕}, M {sub c} = 1.92 ± 0.49 M {sub ⊕}, and M {sub d} = 3.42 ± 0.62 M {sub ⊕}. For HD 106315, we found that such activity radial velocity decorrelation was not effective due to the reduced presence of spots and speculate that this may extend to other hot stars as well (T {sub eff} > 6200 K). We measured planet masses of M {sub b} = 10.5 ± 3.1 M {sub ⊕} and M {sub c} = 12.0 ± 3.8 M {sub ⊕}. We investigated all of the planets’ compositions through comparison of their masses and radii to a range of interior models. GJ 9827 b and GJ 9827 c are both consistent with a 50/50 rock-iron composition, GJ 9827 d and HD 106315 b both require additional volatiles and are consistent with moderate amounts of water or hydrogen/helium, and HD 106315 c is consistent with a ∼10% hydrogen/helium envelope surrounding an Earth-like rock and iron core.

47 OTHER INSTRUMENTATION↗
NASA NTRS2006

MEASURING THE MASS OF 4UO900-40 DYNAMICALLY

Accurate measurements of neutron star masses are needed to constrain the equation of state of neutron star matter - of importance to both particle physics and the astrophysics of neutron stars - and to identify the evolutionary track of the progenitor stars that form neutron stars. The best measured values of the mass of 4UO900-40 (= Vela XR-l), 1.86 +/- 0.16 Msun (Barziv et al. 2001) and 1.93 +/- 0.20 Msun (Abubekerov et al. 2004), make it a leading candidate for the most massive neutron star known. The direct relationship between the maximum mass of neutron stars and the equation of state of ultra-dense matter makes 4UO900-40 an important neutron star mass to determine accurately. The confidence interval on previous mass estimates, obtained from observations that include parameters determined by non-dynamical methods, are not small enough to significantly restrict possible equations of state. We describe here a purely dynamical method for determining the mass of 4UO900-40, an X-ray pulsar, using the reprocessed UV pulses emitted by its BO.5Ib companion. One can derive the instantaneous radial velocity of each component by simultaneous X-ray and UV observations at the two quadratures of the system. The Doppler shift caused by the primary's rotational velocity and the illumination pattern of the X-rays on the primary, two of the three principal contributors to the uncertainty on the derived mass of the neutron star, almost exactly cancel by symmetry in this method. A heuristic measurement of the mass of 4UO900-40 using observations obtained previously with the High Speed Photometer on HST is given in Appendix A.

Dolan, J. F.↗
NASA NTRS1990

Ion mass spectrometer measurements from the Space Shuttle

Ion-mass-spectrometer measurements made, as part of the University of Iowa's Plasma Diagnostic Package, on the STS-3 and Spacelab 2 missions, sampled a variety of positive ion composition perturbations in response to gas emissions from the vehicle. A background of contaminant ion species (mostly relating to water) always exists in the vicinity of the Shuttle. The measured number fluxes of the contaminant ions vary differently from those of the ambient ions in response to changes in the spectrometer and spacecraft angles of attack. There is a near-Shuttle wake cavity in the contaminant ion distributions which has a different spatial configuration than the wake of the ambient ions. Although water dumps produce the longest term ion perturbations, the most well defined effects were observed from measurements taken during the short firings of the reaction-control-system thrusters.

Grebowsky, J. M.↗
NASA NTRS1993

Mass properties measurement system: Dynamics and statics measurements

This report presents and interprets experimental data obtained from the Mass Properties Measurement System (MPMS). Statics measurements yield the center-of-gravity of an unknown mass and dynamics measurements yield its inertia matrix. Observations of the MPMS performance has lead us to specific design criteria and an understanding of MPMS limitations.

Doty, Keith L.↗
DOE OSTI2024

HEU Pancake (Jemima) Plate Preliminary Characterization Report

The HEU pancake (Jemima) plates have been used in multiple International Criticality Safety Benchmark Evaluation Project (ICSBEP) evaluations, including: HEU-MET-FAST-072, HEU-MET-FAST-073, HEU MET-FAST-102, HEU-MET-INTER-006, HEU-MET-INTER-011, HEU-MET-MIXED-021, and IEU MET-FAST-025. This report only focuses on the physical dimension characterization, since concerns have been identified about reliable diameter and height measurements. Historically, height measurements with calipers and mass measurements have been performed for every plate. However, the combination of previous measurements (mass and caliper height measurements) with the drawing dimensions for the diameters led to unrealistic densities (>19 g/cm 3 ) or large ranges of densities for parts that were manufactured at the same time (17 g/cm 3 to >19 g/cm 3 ). Due to the oxidation of the plates, questions about the flatness of each plate and what gaps are introduced into the system have been discussed, since gaps tend to be one of the largest sources of uncertainty in stacked benchmark experiments. The purpose of this report is to characterize a subset of this commonly used fuel. A uniform method for how to define the HEU pancake plates for ICSBEP evaluations will also be proposed with a discussion on what measurements should be performed on the remaining HEU pancake plates in the NCERC inventory.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS2012

Mass Property Measurements of the Mars Science Laboratory Rover

The NASA/JPL Mars Science Laboratory (MSL) spacecraft mass properties were measured on a spin balance table prior to launch. This paper discusses the requirements and issues encountered with the setup, qualification, and testing using the spin balance table, and the idiosyncrasies encountered with the test system. The final mass measurements were made in the Payload Hazardous Servicing Facility (PHSF) at Kennedy Space Center on the fully assembled and fueled spacecraft. This set of environmental tests required that the control system for the spin balance machine be at a remote location, which posed additional challenges to the operation of the machine

rover↗
NASA NTRS2004

Upgrade of the Goddard Space Flight Center's Mass Properties Measuring Facility

Goddard Space Flight Center has a Mass Properties Measuring Facility (MPMF), which is used to measure weight, center of gravity, moment of inertia, and product of inertia of satellites and space flight hardware. The system was originally purchased more than 30 years ago. While the MPMF was still in good mechanical condition, the measurement and control subsystem had begun to experience more frequent component failures. Many of the outdated, discrete components in the system are no longer available for replacement. A decision was made to upgrade the measurement and control subsystem of the MPMF to improve its reliability and reduce the chance of component failures leading to extended facility outages. This paper will describe details of the upgraded subsystems and summarize the new performance capabilities of the system.

Ross, Brian P.↗
NASA NTRS2004

Upgrade of the Goddard Space Flight Center's Mass Properties Measuring Facility

Goddard Space Flight Center has a Mass Properties Measuring Facility (MPMF), which is used to measure weight, center of gravity, moment of inertia, and product of inertia of satellites and space flight hardware. The system was originally purchased more than 30 years ago. While the MPMF was still in good mechanical condition, the measurement and control subsystem had begun to experience more frequent component failures. Many of the outdated, discrete components in the system are no longer available for replacement. A decision was made to upgrade the measurement and control subsystem of the MPMF to improve its reliability and reduce the chance of component failures leading to extended facility outages. This paper will describe details of the upgraded subsystems and summarize the new performance capabilities of the system.

Ross, Brian P.↗
NASA NTRS2004

Measuring the Mass Distribution in Z is Approximately 0.2 Cluster Lenses with XMM, HST and CFHT

Being the most massive gravitationally bound objects in the Universe, clusters of galaxies are prime targets for studies of structure formation and evolution. Specifically the comoving space density of virialized clusters of a given mass (or X-ray temperature), but also the frequency and degree of substructure, as well as the shape of the cluster mass profile are quantities whose current values and evolution as a function of lookback time can provide important constraints on the cosmological and physical parameters of structure formation theories. The project funded by NASA grant NAG 5-10041 intended to take such studies to a new level by combining observations of a well-selected cluster sample by three state-of-the-art telescopes: HST, to accurately measure the mass distribution in the cluster core (approx. 0.5 h(sup -1)(sub 50) Mpc) via strong gravitational lensing; CFHT, to measure the large scale mass distribution out to approx. 3 Mpc via weak lensing; and XMM, to measure the gas density and temperature distribution accurately on intermediate scales < 1.5 Mpc. XMM plays a pivotal role in this context as the calibration of X-ray mass measurements through accurate, spatially resolved X-ray temperature measurements (particularly in the cosmologically most sensitive range of kT> 5 keV) is central to the questions outlined above. This set of observations promised to yield the best cluster mass measurements obtained so far for a representative sample, thus allowing us to: 1) Measure the high-mass end of the local cluster mass function; 2) Test predictions of a universal cluster mass profile; 3) calibrate the mass-temperature and temperature-luminosity relations for clusters and the scatter around these relations, which is vital for studies of cluster evolution using the X-ray temperature and X-ray luminosity functions.

Source record↗
NASA NTRS1947

Three-Component Force and Mass-Flow Measurement on a Jet Nacelle

The present report contains three-component forces and mass-flow measurements on a jet nacelle at small inlet-velocity ratios v(sub A)/v(sub o) < 1. The mass-flow measurement on two cross sections of the nacelle demonstrate the local-velocity distribution with varying flow and angle of attack.

Ilgmann, G.↗
DOE OSTI2024

Combination of Measurements of the Top Quark Mass from Data Collected by the ATLAS and CMS Experiments at s = 7 and 8 TeV

A combination of fifteen top quark mass measurements performed by the ATLAS and CMS experiments at the LHC is presented. The datasets used correspond to an integrated luminosity of up to 5 and 20 fb − 1 of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, respectively. The combination includes measurements in top quark pair events that exploit both the semileptonic and hadronic decays of the top quark, and a measurement using events enriched in single top quark production via the electroweak t channel. The combination accounts for the correlations between measurements and achieves an improvement in the total uncertainty of 31% relative to the most precise input measurement. The result is m t = 172.52 ± 0.14 ( stat ) ± 0.30 ( syst ) GeV , with a total uncertainty of 0.33 GeV. © 2024 CERN, for the CMS and ATLASs Collaboration 2024 CERN

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗