Accuracy of the determination of mean anomalies and mean geoid undulations from a satellite gravity field mapping mission

Improved knowledge of the Earth's gravity field was obtained from new and improved satellite measurements such as satellite to satellite tracking and gradiometry. This improvement was examined by estimating the accuracy of the determination of mean anomalies and mean undulations in various size blocks based on an assumed mission. In this report the accuracy is considered through a commission error due to measurement noise propagation and a truncation error due to unobservable higher degree terms in the geopotential. To do this the spectrum of the measurement was related to the spectrum of the disturbing potential of the Earth's gravity field. Equations were derived for a low-low (radial or horizontal separation) mission and a gradiometer mission. For a low-low mission of six month's duration, at an altitude of 160 km, with a data noise of plus or minus 1 micrometers sec for a four second integration time, we would expect to determine 1 deg x 1 deg mean anomalies to an accuracy of plus or minus 2.3 mgals and 1 deg x 1 deg mean geoid undulations to plus or minus 4.3 cm. A very fast Fortran program is available to study various mission configurations and block sizes

Reliability studies of integrated modular engine system designs

A study was performed to evaluate the reliability of Integrated Modular Engine (IME) concepts. Comparisons were made between networked IME systems and non-networked discrete systems using expander cycle configurations. Both redundant and non-redundant systems were analyzed. Binomial approximation and Markov analysis techniques were employed to evaluate total system reliability. In addition, Failure Modes and Effects Analyses (FMEA), Preliminary Hazard Analyses (PHA), and Fault Tree Analysis (FTA) were performed to allow detailed evaluation of the IME concept. A discussion of these system reliability concepts is also presented

Characterization of aluminum/RP-1 gel propellant properties

Research efforts are being conducted by the NASA Lewis Research Center to formulate and characterize the properties of Al/RP-1 and RP-1 gelled propellants for rocket propulsion systems. Twenty four different compositions of gelled fuels were formulated with 5 and 16 micron, atomized aluminum powder in RP-1. The total solids concentration in the propellant varied from 5 to 60 wt percent. Tests were conducted to evaluate the stability and rheological characteristics of the fuels. Physical separation of the solids occurred in fuels with less than 50 wt percent solids concentration. The rheological characteristics of the Al/RP-1 fuels varied with solids concentration. Both thixotropic and rheopectic gel behavior were observed. The unmetallized RP-1 gels, which were formulated by a different technique than the Al/RP-1 gels, were highly viscoelastic. A history of research efforts which were conducted to formulate and characterize the properties of metallized propellants for various applications is also given

High energy-density liquid rocket fuel performance

A fuel performance database of liquid hydrocarbons and aluminum-hydrocarbon fuels was compiled using engine parametrics from the Space Transportation Engine Program as a baseline. Propellant performance parameters are introduced. General hydrocarbon fuel performance trends are discussed with respect to hydrogen-to-carbon ratio and heat of formation. Aluminum-hydrocarbon fuel performance is discussed with respect to aluminum metal loading. Hydrocarbon and aluminum-hydrocarbon fuel performance is presented with respect to fuel density, specific impulse, and propellant density specific impulse

Photon production in relativistic nuclear collisions at SPS and RHIC energies

Chiral Lagrangians are used to compute the production rate of photons from the hadronic phase of relativistic nuclear collisions. Special attention is paid to the role of the pseudovector a_1 meson. Calculations that include reactions with strange mesons, hadronic form factors and vector spectral densities consistent with dilepton production, as well as the emission from a quark-gluon plasma and primordial nucleon-nucleon collisions, reproduce the photon spectra measured at the Super Proton Synchrotron (SPS). Predictions for the Relativistic Heavy Ion Collider (RHIC) are made.Comment: Work presented at the 26th annual Montreal-Rochester-Syracuse-Toronto conference (MRST 2004) on high energy physics, Montreal, QC, Canada, 12-14 May 2004. 8 pages, 3 figure

Theory and Phenomenology of Heavy Flavor at RHIC

We review the problem of heavy-quark diffusion in the Quark-Gluon Plasma and its ramifications for heavy-quark spectra in heavy-ion collisions at RHIC. In particular, we attempt to reconcile underlying mechanisms of several seemingly different approaches that have been put forward to explain the large suppression and elliptic flow of non-photonic electron spectra. We also emphasize the importance of a quantitative description of the bulk medium evolution to extract reliable values for the heavy-quark diffusion coefficient.Comment: 8 pages latex, including 10 eps figures; plenary talk at SQM08, Beijing (China), Oct. 06-10, 200

Flow visualization of a rocket injector spray using gelled propellant simulants

A study was conducted at NASA-Lewis to compare the atomization characteristics of gelled and nongelled propellant simulants. A gelled propellant simulant composed of water, sodium hydroxide, and an acrylic acid polymer resin (as the gelling agent) was used to simulate the viscosity of an aluminum/PR-1 metallized fuel gel. Water was used as a comparison fluid to isolate the rheological effects of the water-gel and to simulate nongelled RP-1. The water-gel was injected through the central orifice of a triplet injector element and the central post of a coaxial injector element. Nitrogen gas flowed through the outer orifices of the triplet injector element and through the annulus of the coaxial injector element and atomized the gelled and nongelled liquids. Photographs of the water-gel spray patterns at different operating conditions were compared with images obtained using water and nitrogen. A laser light was used for illumination of the sprays. The results of the testing showed that the water sprays produced a finer and more uniform atomization than the water-gel sprays. Rheological analysis of the water-gel showed poor atomization caused by high viscosity of water-gel delaying the transition to turbulence

Effect of resonance decays on hadron elliptic flows

The influence of resonance decays on the elliptic flows of stable hadrons is studied in the quark coalescence model. Although difference between the elliptic flow of pions from resonance decays, except the rho meson, and that of directly produced pions is appreciable, those for other stable hadrons are small. Since there are more pions from the decays of rho mesons than from other resonances, including resonance decays can only account partially the deviation of final pion elliptic flow from the observed scaling of hadron elliptic flows, i.e., the hadron elliptic flow per quark is the same at same transverse momentum per quark. The remaining deviation can be explained by including the effect due to the quark momentum distribution inside hadrons.Comment: 13 pages and 5 figures, version pubblished in PRC, updated references and figure

Expression of the murine cytomegalovirus glycoprotein H by recombinant vaccinia virus

The sequence of the gene encoding glycoprotein H (gH) of murine cytomegalovirus (MCMV) strain Smith was determined and compared with the sequence of the gH of MCMV strain K181. Transcriptional analysis showed that gH is encoded by a large mRNA of 5.0 kb, which is synthesized late in infection. A recombinant vaccinia virus expressing the MCMV gH open reading frame was constructed (Vac-gH). Anti-MCMV serum precipitated a protein of 87K from Vac-gH-infected cells. Reactivity with a monoclonal antibody showed the identity of the MCMV gH with a 87K envelope glycoprotein described previously by Loh and Qualtiere. Immunization of mice with the Vac-gH recombinant gave rise to an anti-gH serum, which neutralized MCMV without complement in vitro