Studies on Emission Processes in Optically Pumped Mercury Vapor

Electron transitions in optically pumped mercury vapor emissio

Study of ephemeris accuracy of the minor planets

The current state of minor planet ephemerides was assessed, and the means for providing and updating these emphemerides for use by both the mission planner and the astronomer were developed. A system of obtaining data for all the numbered minor planets was planned, and computer programs for its initial mechanization were developed. The computer based system furnishes the osculating elements for all of the numbered minor planets at an adopted date of October 10, 1972, and at every 400 day interval over the years of interest. It also furnishes the perturbations in the rectangular coordinates relative to the osculating elements at every 4 day interval. Another computer program was designed and developed to integrate the perturbed motion of a group of 50 minor planets simultaneously. Sampled data resulting from the operation of the computer based systems are presented

Shallow grooves in journal improve air bearing performance

Bearing designs, which shape the surface to create artificial fluid-film wedges in the absence of any applied radial load, generate radial restoring forces to keep journals from whirling. Helical- or herringbone-grooved journals or rotors show most promise of stable operation, with no sacrifice in load capacity

Experimental dynamic stiffness and damping of externally pressurized gas-lubricated journal bearings

A rigid vertical shaft was operated with known amounts of unbalance at speeds to 30,000 rpm and gas supply pressure ratios to 4.8. From measured amplitude and phase angle data, dynamic stiffness and damping coefficients of the bearings were determined. The measured stiffness was proportional to the supply pressure, while damping was little affected by supply pressure. Damping dropped rapidly as the fractional frequency whirl threshold was approached. A small-eccentricity analysis overpredicted the stiffness by 20 to 70 percent. Predicted damping was lower than measured at low speeds but higher at high speeds

Experiments on rotating externally pressurized air journal bearings. Part 2 - Attitude angle and air flow

Air flow and attitude angle compared with theory for rotating externally pressurized air journal bearing

Federal support and stimulation of interdisciplinary research in universities

Federal support and stimulation of interdisciplinary research in university social and physical science department

Computer vision

The field of computer vision is surveyed and assessed, key research issues are identified, and possibilities for a future vision system are discussed. The problems of descriptions of two and three dimensional worlds are discussed. The representation of such features as texture, edges, curves, and corners are detailed. Recognition methods are described in which cross correlation coefficients are maximized or numerical values for a set of features are measured. Object tracking is discussed in terms of the robust matching algorithms that must be devised. Stereo vision, camera control and calibration, and the hardware and systems architecture are discussed

Performance of alumina-supported Pt catalysts in an electron-beam-sustained CO2 laser amplifier

The performance of an alumina-supported Pt catalyst system used to maintain the gas purity in an electron-beam-sustained (636) isotope CO2 laser amplifier has been tested. The system characteristics using the two-zone, parallel flow reactor were determined for both continuous- and end-of-day reactor operation using on-line mass spectrometric sampling. The laser amplifier was run with an energy loading of typically 110 J-l/atm and an electron-beam current of 4 mA/sq cm. With these conditions and a pulse repetition frequency of 10 Hz for up to 10,000 shots, increases on the order of 100 ppm O2 were observed with the purifier on and 150 ppm with it off. The 1/e time recovery time was found to be approximately 75 minutes

Vibration Characteristics Of Free Thin Cylindrical Shells

This paper considers the flexural vibrations of free thin circular cylinders. A frequency equation is derived using free-free characteristic beam functions to represent the variation of mid-surface shell displacement components, u, v and w, with respect to the axial direction. Timoshenko strain-displacement relations for thin cylinders are used to determine elastic vibratory strain energy. Energy methods are applied to obtain the frequency equation and associated amplitude ratios for each of its roots. This energy solution is checked experimentally using a vibration exciter and numerically using the SABOR IV finite element program. With minor modification, the frequency equation conforms to the one obtained in a similar way by Arnold and Warburton for cylinders with clamped ends and simply supported ends. Thus the proposed form of frequency equation, by accommodating a greater variety of boundary conditions, simplifies the task of determining cylinder vibration characteristics. © 1974 by ASME