Engineering topics

Mizutani, H.

Publications and source records attributed to Mizutani, H..

13 records

NASA NTRS1989

Effects of lubrication on the performance of high speed spur gears

An experimental analysis was conducted to determine power loss and gear noise of high speed spur gears with long addendum under various conditions of load, speed, and oil jet pressure for into mesh lubrication. Power losses were calculated from temperature measurements of lubricating oil, gears, gear box, and oil flow rate. Furthermore, power loss was divided into windage loss, friction loss and churning loss. The results show that windage loss and churning loss were the main components of gear power loss of high gear speed. In addition, lubricating conditions had some influences on gear noise especially under low oil temperature or high viscosity.

Mizutani, H.↗

NASA NTRS1983

Cratering experiments in sands and a trial for general scaling law

The results of the vertical impacts of aluminum projectiles into quartz sand are reported. The impacts are at velocities of 35 to 830 m/sec with a single-stage powder gun. The morphology of craters formed in loose sands is generally conical, whereas that of craters formed in self-compacted sands varies with increasing impact velocity from a flat-floor type to a double-ring type. The present data, together with previous experimental data and the 'late-stage equivalence' of Dienes and Walsh, are seen as indicating that the crater diameter is expressed by a function of the 'late-stage effective energy' but not of the impact kinetic energy. The diameter of a crater formed in a noncohesive sand is found to be proportional to one-fourth the power of the late-state effective energy. For general impact cratering in a target with a finite strength, a relation is given between the velocity and the diameter, suggesting that there are four regimes in the crater diameter versus kinetic energy relation.

Mizutani, H.↗

NASA NTRS1981

Effect of polynucleotides on the dimerization of glycine

Results from experiments to determine the effect of polynucleotides on abiological formation of peptide bonds are reported. The reaction between glycine molecules in an aqueous phase in the presence of a condensing agent was chosen as a model, with polyphosphates being selected as the condensing agent for biologically relevant peptide formation. Four types of polynucleotides were used: polygluanic acid (G), polyuridic acid (U), polyadenylic acid (A), and polycytidylic acid (C); the effects of small anions, acetate, chloride, and phosphate, were also studied. Procedures are given, including concentrations, pH, and incubation time, and the type of amino acid analyzer. The diglycine yields were, in order of most to least: G, C, A, U, and are diagrammed as a function of time; rate of formation followed the same order of magnitude as the final yields. Anion presence displayed no discernible effect. The results are taken to indicate that polynucleotides do have an effect on the formation of peptide bonds, an effect significant in the understanding of chemical evolution.

Mizutani, H.↗

NASA NTRS1979

Comparison of single crack propagation in lunar analogue glass and the failure strength of rocks

New data of crack propagation in lunar analogue glass provides important input for the construction of deformation maps (maps which delineate the rates and principal means of material deformation under various environmental conditions) applicable to the lunar crust. Comparison of single crack propagation data obtained on flat plates of glass and failure strength data obtained on fine grained rock samples show that single crack propagation velocities are directly related to the failure strength of rocks. The chemical reaction between water and silicon-oxygen bonds at the crack tip seems to be of first order. This greatly simplifies extrapolation to low partial pressures of H2O

Soga, N.↗

NASA NTRS1978

The effect of dilatancy on velocity anisotropy in Westerly granite

Jacketed samples of Westerly granite were fractured at confining pressures up to 1 kbar, and compressional and horizontally as well as vertically polarized shear velocities were measured in orthogonal directions perpendicular to the compression axis. Changes occurring with increased strain are described, and the velocity data were analyzed by application of the Anderson et al (1974) approach. Observed and calculated velocities are found to be in good agreement, and the degree of dilatancy was determined from the differences between the strains measured perpendicularly to the compression axis and the estimated elastic strains in those directions.

Soga, N.↗

NASA NTRS1978

Gravitational N-body problem on the accretion process of terrestrial planets

Numerical integration of the gravitational N-body problem has been carried out for a variety of protoplanetary clusters in the range N = 100 to 200. Particles are assumed to coagulate at collisions irrespective of relative velocity and mass ratio of the particles. It is shown graphically how the dispersed N-bodies accumulate to a single planet through mutual collisions. The velocity distribution and size distribution of bodies are also investigated as functions of time in the accretion process. Accretion rates of planets are found to be dependent strongly on the initial number density distribution, the initial size distribution, and the initial velocity distribution of bodies. Formation of satellites of about 10% in the planet mass is common to most cases in the present study. A substantial mass of bodies also escapes from the cluster. Many satellites and escapers formed during the accretion process of planets may be source materials of heavy bombardment in the early history of planets.

Matsui, T.↗

NASA NTRS1977

Why is a minor planet minor

A hypothesis based on the accretion model of planet formation is proposed which can explain why minor planets could not grow into full-sized planets. Temperature and impact-velocity conditions for bouncing, accumulation, and fragmentation of planetesimals are evaluated for silicate and iron planetesimals at the heliocentric distances of Mercury, Venus, earth, Mars, and the asteroid belt. The results indicate that the low-temperature environment of the asteroids very likely hampered their growth into ironlike planetesimals, which in turn inhibited the accumulation of silicate planetesimals. It is concluded that the brittleness of iron at temperatures below 200 to 250 K is the primary reason why minor planets are 'minor' and could not grow to full size.

Matsui, T.↗

NASA NTRS1977

The evolution of the protein synthesis system. I - A model of a primitive protein synthesis system

A model is developed to describe the evolution of the protein synthesis system. The model is comprised of two independent autocatalytic systems, one including one gene (A-gene) and two activated amino acid polymerases (O and A-polymerases), and the other including the addition of another gene (N-gene) and a nucleotide polymerase. Simulation results have suggested that even a small enzymic activity and polymerase specificity could lead the system to the most accurate protein synthesis, as far as permitted by transitions to systems with higher accuracy.

Mizutani, H.↗

NASA NTRS1977

The effect of outgassing upon the closure of cracks and the strength of lunar analogues

The effect of an ultrahigh vacuum and low water vapor pressure on the stress-strain relation in rocks was studied in order to understand geologic and tectonic processes of the moon. Terrestrial basaltic rocks carefully outgassed in high vacuum provided the sample material for the compression tests reported here. The tests were conducted either under 1 atm air saturated with moisture, or under high vacuum. Results of the stress-strain determinations indicated that the dry rocks could show as much as twice the strength of the wet rocks. The data may also provide a means of reconciling the high strength and high temperature exhibited by the lunar interior.

Mizutani, H.↗

NASA NTRS1973

Elastic wave velocities of Apollo 14, 15, and 16 rocks

Elastic wave velocities of two Apollo 14 rocks, 14053 and 14321, three Apollo 15 rocks, 15058, 15415, and 15545, and one Apollo 16 rock 60315 have been determined at pressures up to 10 kb. For sample 14321, the variation of the compressional wave velocities with temperature has been measured over the temperature range from 27 to 200 C. Overall elastic properties of these samples except sample 15415 are very similar to those of Apollo 11, 12, and 14 rocks and are concordant with Toksoz et al.'s (1972) interpretation that lunar upper crust is of basaltic composition. Temperature derivative of the P wave velocity for sample 14321 is a half to one order of magnitude larger than that for single crystalline minerals. This suggests that the seismic velocity in the lunar crust may be affected significantly by the temperature distribution.

Mizutani, H.↗

NASA NTRS1972

Accretion process of the moon.

Development of a simple model of the accretion process of the moon to explain its initial temperature distribution. The model assumes that the moon was formed from the accumulation of the solid particles or gases in the isolated, closed cloud. Two equations are derived to calculate the accretion rate and surface temperature of the accreting moon. Numerical calculations are made for a wide range of the particle concentrations and particle velocities in the cloud. A limited set of parameters gives the initial temperature profiles as required by geochemical and geophysical data. These models of the protomoon cloud indicate that the lunar outershell, about 400 km thick, was partially or completely molten just after the accretion of the moon and that the moon should have been formed in a period shorter than 1000 yr. If the moon formed at a position nearer to the earth than its present one, the moon might have been formed in a period of less than one year.

Mizutani, H.↗

NASA NTRS1972

Accretion process of the moon

Recent geochemical and geophysical data suggest that the initial temperature of the moon was strongly peaked toward the lunar surface. To explain such an initial temperature distribution, a simple model of accretion process of the moon is presented. The model assumes that the moon was formed from the accumulation of the solid particles or gases in the isolated, closed cloud. Two equations are derived to calculate the accretion rate and surface temperature of the accreting moon. Numerical calculations are made for a wide range of the parameters particle concentration and particle velocity in the cloud. A limited set of the parameters gives the initial temperature profiles as required by geochemical and geophysical data. These models of the proto-moon cloud indicate that the lunar outermost shell, about 400 km thick, was partially or completely molten just after the accretion of the moon and that the moon should have been formed in a period shorter than 1000 years. If the moon formed at a position nearer to the earth than its present one, the moon might have been formed in a period of less than one year.

Mizutani, H.↗

NASA NTRS1972

Elastic wave velocities and thermal diffusivities of Apollo 14 rocks.

The compressional- and shear-wave velocities of Apollo 14 lunar rocks 14311,50 and 14313,27 as functions of pressure up to 10 kb and the thermal diffusivity of sample 14311,50 over the temperature range 100 to 550 K have been measured. Both samples 14311 and 14313 are polymict fragmental rocks. The overall elastic and anelastic behavior of the Apollo 14 samples are similar to those of Apollo 11 and 12 samples; low velocity and low Q at pressures below 1 kb and rapid increase of velocity and Q with pressure are also typical of the Apollo 14 rocks. The available data of P- and S-wave velocities of lunar rocks show that Birch's law holds for the lunar rocks. The thermal diffusivity of a lunar rock in vacuum is found to be significantly lower than that in air at one atmospheric pressure.

Mizutani, H.↗