Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “kinematic”

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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Interplanetary stream magnetism - Kinematic effects

The particle density and the magnetic-field intensity and direction are calculated for volume elements of the solar wind as a function of the initial magnetic-field direction and the initial speed gradient. It is assumed that the velocity is constant and radial. These assumptions are approximately valid between about 0.1 and 1.0 AU for many streams. Time profiles of the particle density, field intensity, and velocity are calculated for corotating streams, neglecting effects of pressure gradients. The compression and rarefaction of the magnetic field depend sensitively on the initial field direction. By averaging over a typical stream, it is found that the average radial field intensity is inversely proportional to the square of the heliocentric distance, whereas the average intensity in the direction of the planets' motion does not vary in a simple way, consistent with deep space observations. Changes of field direction may be very large, depending on the initial angle; but when the initial angle at 0.1 AU is such that the base of the field line corotates with the sun, the spiral angle is the preferred direction at 1 AU. The theory is also applicable to nonstationary flows.

Burlaga, L. F.↗
NASA NTRS1975

Kinematic constraints on the production of magnetic monopoles

A strict lower limit is derived for the laboratory kinetic energy of a magnetic monopole produced from a target at rest. The production of a monopole-antimonopole pair via the collision of a projectile with a target at rest in the laboratory is analyzed in terms of the velocity of the zero-momentum frame, the velocity of the monopole in that frame, and the velocity of the monopole in the laboratory. The limit obtained is applied to the data of Price et al. (1975), and almost all means of producing the monopole in the atmosphere immediately above the balloon-borne detectors are ruled out. Some mechanisms for slowing a monopole following its production are briefly considered.

Wilson, L. W.↗
NASA NTRS1977

Turbulent diffusion from a quasi-kinematical point of view

An estimate for the coefficient of self-diffusion can be derived whenever the Eulerian velocity spectrum is known. The result is more general than those previously obtained. A comparison is made with computed test-particle diffusion in an inviscid two-dimensional Navier-Stokes fluid.

Salu, Y.↗
NASA NTRS1977

Electron kinematics in a plasma focus

The results of numerical integrations of the three-dimensional relativistic equations of motion of electrons subject to given electric and magnetic fields are presented. Fields due to two different models are studied: (1) a circular distribution of current filaments, and (2) a uniform current distribution; both the collapse and the current reduction phases are studied in each model. Decreasing current in the uniform current model yields 100 keV electrons accelerated toward the anode and, as for earlier ion computations, provides general agreement with experimental results.

Hohl, F.↗
NASA NTRS1978

Thermal structure and kinematics of mid-oceanic ridge axis - Some implications to basaltic volcanism

Based on studies of ophiolitic complexes, a characterization of basaltic magmas at midocean ridges is proposed. A thin molten region about 3 km wide probably exists at the top of the magma chamber; primitive material enters the uppermost part of the chamber from below, and fractionated material is removed by the upward extrusion of dikes and settling of crystals to form a mush which probably fills the bulk of the chamber. The roof of the magma chamber is probably cooler than the melting temperature of primitive basalt. Secondary melts and the volume of the uppermost molten region are considered. Weaknesses along the line of dike intrusion and limited plating of material onto the roof of the chamber may restrict dike intrusion to the exceeding narrow zone inferred from ophiolitic complexes.

Sleep, N. H.↗
NASA NTRS1980

Design study of a kinematic Stirling engine for dispered solar electric power systems

The concept evaluation shows that the four cylinder double acting U type Stirling engine with annular regenerators is the most suitable engine type for the 15 kW solar application with respect to design, performance and cost. Results show that near term performance for a metallic Stirling engine is 42% efficiency. Further improved components show an impact on efficiency of the future metallic engine to 45%. Increase of heater temperature, through the introduction of ceramic components, contribute the greatest amount to achieve high efficiency goals. Future ceramic Stirling engines for solar applications show an efficiency of around 50%.

Source record↗
NASA NTRS1980

An error analysis of basic kinematic quantities

A description is presented of the computational procedures used to obtain spatial fields of relative vorticity, advection of vorticity, horizontal divergence, and vertical motion. An investigation is conducted of the effectiveness of these procedures to reduce the effects of deliberately introduced random errors, giving attention to the confidence which can be placed on values of the derived parameters. It is concluded that fields of 500 mb vorticity and 700 mb vertical velocity, which are frequently used in synoptic scale forecasting schemes, show minimal effects of the deliberately introduced errors. Vorticity advection is found to be the most sensitive term to input data errors. Large fluctuations in fields of this parameter are evident both statistically and qualitatively.

Berecek, E. M.↗
NASA NTRS1982

Motion of the Jovian commensurability resonances and the character of the celestial mechanics in the asteroid zone - Implication for kinematics and structure

The motion of the Jovian commensurability resonances during the early evolution of the solar system induced by the dissipation of the accretion disk results in fundamental differences in the celestial mechanics of objects over which a resonance passes from that observed for a stationary resonance. Objects experiencing resonance passage acquire irreversible increases of average eccentricity to large values accounting for the present-day random velocities of the asteroids. Semi-major axes are similarly irreversibly decreased by amounts capable of clearing the Kirkwood gaps. The gap widths are in agreement with observation.

Torbett, M.↗
NASA NTRS1983

Prediction of ball and roller bearing thermal and kinematic performance by computer analysis

Characteristics of good computerized analysis software are suggested. These general remarks and an overview of representative software precede a more detailed discussion of load support system analysis program structure. Particular attention is directed at a recent cylindrical roller bearing analysis as an example of the available design tools. Selected software modules are then examined to reveal the detail inherent in contemporary analysis. This leads to a brief section on current design computation which seeks to suggest when and why computerized analysis is warranted. An example concludes the argument offered for such design methodology. Finally, remarks are made concerning needs for model development to address effects which are now considered to be secondary but are anticipated to emerge to primary status in the near future.

Pirvics, J.↗
NASA NTRS1983

The actual content of quantum theoretical kinematics and mechanics

First, exact definitions are supplied for the terms: position, velocity, energy, etc. (of the electron, for instance), such that they are valid also in quantum mechanics. Canonically conjugated variables are determined simultaneously only with a characteristic uncertainty. This uncertainty is the intrinsic reason for the occurrence of statistical relations in quantum mechanics. Mathematical formulation is made possible by the Dirac-Jordan theory. Beginning from the basic principles thus obtained, macroscopic processes are understood from the viewpoint of quantum mechanics. Several imaginary experiments are discussed to elucidate the theory.

Heisenberg, W.↗
NASA NTRS1984

Kinematics, influence functions and field quantities for disturbance propagation from moving disturbance sources

A unified method is presented for deriving the influence functions of moving singularities which determine the field quantities in aerodynamics and aeroacoustics. The moving singularities comprise volume and surface distributions having arbitrary orientations in space and to the trajectory. Hence one generally valid formula for the influence functions which reveal some universal relationships and remarkable properties in the disturbance fields. The derivations used are completely consistent with the physical processes in the propagation field, such that treatment renders new descriptions for some standard concepts. The treatment is uniformly valid for subsonic and supersonic Mach numbers.

Das, A.↗
NASA NTRS1984

Translational control of a graphically simulated robot arm by kinematic rate equations that overcome elbow joint singularity

An operator commands a robot hand to move in a certain direction relative to its own axis system by specifying a velocity in that direction. This velocity command is then resolved into individual joint rotational velocities in the robot arm to effect the motion. However, the usual resolved-rate equations become singular when the robot arm is straightened. To overcome this elbow joint singularity, equations were developed which allow continued translational control of the robot hand even though the robot arm is (or is nearly) fully extended. A feature of the equations near full arm extension is that an operator simply extends and retracts the robot arm to reverse the direction of the elbow bend (difficult maneuver for the usual resolved-rate equations). Results show successful movement of a graphically simulated robot arm.

Barker, L. K.↗
NASA NTRS1984

Southern ocean sea-ice morphology and kinematics

A pilot satellite experiment is described which would employ shuttle imaging radar (SIR) to determine the applicability of imaging radar for the description of sea ice type and movement. The experimental objectives, design, and anticipated results are discussed. The results are expected to constitute an important contribution to the understanding of the role of sea ice in air-sea interactions in polar regions. It is proposed that shuttle photography, thematic mapper imagery, and SIR data be utilized in this remote sensing project.

Carsey, F.↗
NASA NTRS1985

Kinematic rate control of simulated robot hand at or near wrist singularity

A robot hand should obey movement commands from an operator on a computer program as closely as possible. However, when two of the three rotational axes of the robot wrist are colinear, the wrist loses a degree of freedom, and the usual resolved rate equations (used to move the hand in response to an operator's inputs) are indeterminant. Furthermore, rate limiting occurs in close vicinity to this singularity. An analysis shows that rate limiting occurs not only in the vicinity of this singularity but also substantially away from it, even when the operator commands rotational rates of the robot hand that are only a small percentage of the operational joint rate limits. Therefore, joint angle rates are scaled when they exceed operational limits in a real time simulation of a robot arm. Simulation results show that a small dead band avoids the wrist singularity in the resolved rate equations but can introduce a high frequency oscillation close to the singularity. However, when a coordinated wrist movement is used in conjunction with the resolved rate equations, the high frequency oscillation disappears.

Barker, K.↗
NASA NTRS1984

Kinematics of Saturn's spokes

Voyager 2 images of Saturn's rings have been analyzed for spoke activity. More than 80 and 40 different spokes have been measured at the morning and at the evening ansa, respectively. Higher rate of spoke formation has been found at 145 + or 15 deg SLS and at 305 + or - 15 deg SLS which persisted for at least 3 Saturn revolutions. Higher spoke activity (formation and growth in width) by more than a factor 3 has been observed over the nightside hemisphere of Saturn than over the dayside hemisphere. The age distribution (i.e., time from radial formation until observation, assuming Keplerian shear) of the leading (old) edges of spokes has its maximum at approximately 9,000 s and 6,000 s for spokes observed at the morning ansa and at the evening ansa, respectively. The highest spoke age observed is approximately 20,000 s.

Gruen, E.↗