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Results of experimental research on the noise and vibrations of radial ball and roller bearings are reported. Analysis of the frequency spectra disclosed dependences among vibration and noise, load, rpm and cage material. Some peculiar aspects of the frequency spectrum are also mentioned.
The thermostatic properties of a high-symmetry phase of metallic hydrogen with atomic sphere radius between 0.1 and 1.5 bohr are studied, with special emphasis accorded to electronic screening and quantum proton motion. The electron-proton and proton-proton interactions receive a perturbation treatment based on the Singwi dielectric function, while the proton motion is handled by self-consistent harmonic approximation. Quantum behavior is found to be less pronounced than expected, and nuclear magnetism is absent. The phonon spectrum is, however, affected by screening and large proton motion. The zero-point vibrational energy and the superconducting critical temperature are below previous estimates. The crystalline-defect formation energies are a few times the Debye energy, which implies that defects contribute significantly to melting at the lower particle densities.
First measurements of electron impact excitation on the O2 a delta-one sub g metastable state to a higher bound state, pi-one sub u, is reported. The data were taken at an incident electron energy of 500 eV and scattering angles of 0 deg to 15 deg. A superelastic electron scattering experiment was performed on the pure oxygen target gas in order to establish the composition of the discharged oxygen and to confirm the existence of delta-one sub g molecules in the interaction region. The electron-impact energy loss spectrum obtained is shown. The electronic assignment of the upper state which produces the vibrational structure was determined to be pi-one sub u by examining the potential energy curves of O2 and applying the electric dipole selection rules. The relative line intensities were obtained and used to determine the Morse potential for the pi-one sub u state.
A high-resolution (0.059/cm) M band (4.6 micron) spectrum of the embedded young stellar object M8E-IR is presented and discussed. The spectrum shows strong absorption to large blueshifts in the rotational lines of the fundamental vibrational band, v = 1-0, of CO. The absorption is interpreted as being due to gas near to, and flowing from, the central object. The outflowing gas is warm (95-330 K) and consists of discrete velocity components with the very high velocities of 90, 130, 150, and 160 km/s. On the basis of a simple model, it is estimated that the observed outflows are less than 100 yr old.
The spectroscopy of the NO(+) molecule has been studied using multireference configuration-interaction calculations. The peak at 21.7 eV in the photoelectron spectrum of NO is assigned to the (2) 3Pi state (c 3Pi) and the vibrational progression centered at 23.1 eV is assigned to the diabatic (3) 1Pi state (B 1Pi). Several additional bound states with binding energies in excess of 1 eV are characterized in the present work. Radiative lifetimes are presented for many of the states.
The crawler transporter (CT) is the world's largest tracked vehicle known, weighing 6 million pounds with a length of 131 feet and a width of 113 feet. The Kennedy Space Center (KSC) has two CTs that were designed and built for the Apollo program in the 1960's, maintained and retrofitted for use in the Space Shuttle program. As a key element of the Space Shuttle ground systems, the crawler transports the entire 12-million-pound stack comprising the orbiter, the mobile launch platform (MLP), the external tank (ET), and the solid rocket boosters (SRB) from the Vehicle Assembly Building (VAB) to the launch pad. This rollout, constituting a 3.5-5.0-mile journey at a top speed of 0.9 miles-per-hour, requires over 8 hours to reach either Launch Complex 39A or B. This activity is only a prelude to the spectacle of sound and fury of the Space Shuttle launch to orbit in less than 10 minutes and traveling at orbital velocities of Mach 24. This paper summarizes preliminary results from the Crawler Transporter Sound Attenuation Study, encompassing test and engineering analysis of significant sound sources to measure and record full frequency spectrum and intensity of the various noise sources and to analyze the conditions of vibration. Additionally, data such as ventilation criteria, plus operational procedures were considered to provide a comprehensive noise suppression design for implementation. To date, sound attenuation study and results on Crawler 2 have shown significant noise reductions ranging from 5 to 24 dBA.
Various methods of calculating the internal energy of diatomic molecules are studied. An accurate and efficient method for computing the eigenvalues of the vibrational Schroedinger equation for an arbitrary potential is developed. The method is based on a finite-element discretization using the cubic Lobatto element. A combination of spectrum slicing and the Laguerre algorithm is used to solve for the eigenvalues. A simple method to compute the quasi-bound states is presented. For N2 molecules, all vibrational-rotational states of eleven available electronic potentials are computed, and summed to obtain the exact internal energy function with temperature. The total computation required 314 seconds of CPU-time on NASA's Cray 2 computer. Various approximate models are discussed and compared with the exact numerical simulation. It is shown that the splitting of the macroscopic internal energy into separate electronic, rotational, and vibrational energies is not justified at high temperatures.
The article discusses several optical configurations used for signal processing. Electronic-to-optical transducers are outlined, noting fixed window transducers and moving window acousto-optic transducers. Folded spectrum techniques are considered, with reference to wideband RF signal analysis, fetal electroencephalogram analysis, engine vibration analysis, signal buried in noise, and spatial filtering. Various methods for radar signal processing are described, such as phased-array antennas, the optical processing of phased-array data, pulsed Doppler and FM radar systems, a multichannel one-dimensional optical correlator, correlations with long coded waveforms, and Doppler signal processing. Means for noncoherent optical signal processing are noted, including an optical correlator for speech recognition and a noncoherent optical correlator.
Silicon dicarbide was first observed in 1926 in spectra of cool carbon stars. The carrier of these bands around 5000 A was tentatively identified as SiC2 by Kleman (1956) who produced similar spectra by inserting silicon into the graphite tube of a King furnace heated to over 2500 K. This identification was strengthened by subsequent mass spectral studies which showed SiC2 as a major molecular component of vaporized silicon carbide. The present investigation is concerned with calculations which were initiated in an attempt to understand more recent astronomical observations of unidentified lines in the millimeter-wave region of the spectrum. The calculations were designed to determine the ground state equilibrium structure and to obtain vibrational and rotational constants. Calculations for estimating the positions and structure of low-lying electronic states were also performed. Self-consistent field (SCF) calculations were performed assuming a closed-shell electronic structure analogous to that in C3. Calculations were conducted for symmetric CSiC, and asymmetric SiCC forms.
The topic is addressed of building vibration response to sonic boom and the evaluation of the associated human response to this vibration. An attempt is made to reexamine some of the issues addressed previously and to offer fresh insight that may assist in reassessing the potential impact of sonic boom over populated areas. Human response to vibration is reviewed first and a new human vibration response criterion curve is developed as a function of frequency. The difference between response to steady state versus impulsive vibration is addressed and a 'vibration exposure' or 'vibration energy' descriptor is suggested as one possible way to evaluate duration effects on response to transient vibration from sonic booms. New data on the acoustic signature of rattling objects are presented along with a review of existing data on the occurrence of rattle. Structural response to sonic boom is reviewed and a new descriptor, 'Acceleration Exposure Level' is suggested which can be easily determined from the Fourier Spectrum of a sonic boom. A preliminary assessment of potential impact from sonic booms is provided in terms of human response to vibration and detection of rattle based on a synthesis of the preceding material.
Nuclear quadrupole hyperfine structure has been observed in the 1-0 vibration-rotation band of hydrogen iodide with a tunable-diode laser. The measured splittings agree well with microwave measurements of the HI molecule. Evidence for a slight change in the iodine nuclear quadrupole coupling constant from the ground to first excited vibrational state in hydrogen iodide was found.
We report the first observations of the 13.5 micron fundamental band of SiS in the spectrum of the heavily obscured carbon star IRC +10216. The lines are formed in the inner region of the circumstellar envelope where the gas is accerlerating and where the temperature ranges from 800-500 K. We have carried out a detailed model of the observed line profiles. Our observations are best fit by a gradient in the abundance of SiS. We derive an abundance relative to molecular hydrogen of x(SiS) = 4.3 x 10(exp -6) at a distance of twelve stellar radii from the central star rising to x(SiS) = 4.3 x 10(exp -5) at a few stellar radii from the surface of the star.
Several molecules thus far have been detected in the ISM in vibrationally-excited states, including H2, SiO, HC3N, and CH3CN. In order for vibrational-excitation to occur, these species must be present in unusually hot and dense gas and/or where strong infrared radiation is present. In order to do a more thorough investigation of vibrational excitation in the interstellar medium (ISM), studies were done of several mm-wave transitions originating in excited vibrational modes of HCN, an abundant interstellar molecule. Vibrationally-excited HCN was recently detected toward Orion-KL and IRC+10216, using a 12 meter antenna. The J=3-2 rotational transitions were detected in the molecule's lowest vibrational state, the bending mode, which is split into two separate levels, due to l-type doubling. This bending mode lies 1025K above ground state, with an Einstein A coefficient of 3.6/s. The J=3-2 line mode of HCN, which lies 2050K above ground state, was also observed toward IRC+10216, and subsequently in Orion-KL. Further measurements of vibrationally-excited HCN were done using a 14 meter telescope, which include the observations of the (0,1,0) and (0,2,0) modes towards Orion-KL, via their J=3-2 transitions at 265-267 GHz. The spectrum of the J=3-2 line in Orion taken with the 14 meter telescope, is shown, along with a map, which indicates that emission from vibrationally-excited HCN arises from a region probably smaller than the 14 meter telescope's 20 arcsec beam.
Multiphonon relaxation in neodymium doped lanthanum chloride, determining transition rates between stark levels with lifetime and quantum efficiency measurements
The relative benefits of passive and active vibration suppression for large space structures (LSS) are discussed. The intent is to sketch the true ranges of applicability of these approaches using previously published technical results. It was found that the distinction between active and passive vibration suppression approaches is not as sharp as might be thought at first. The relative simplicity, reliability, and cost effectiveness touted for passive measures are vitiated by 'hidden costs' bound up with detailed engineering implementation issues and inherent performance limitations. At the same time, reliability and robustness issues are often cited against active control. It is argued that a continuum of vibration suppression measures offering mutually supporting capabilities is needed. The challenge is to properly orchestrate a spectrum of methods to reap the synergistic benefits of combined advanced materials, passive damping, and active control.
The pure rotational spectrum of MgH radical (X 2 Sigma (+)) in its ground state v = 0 and v = 1 vibrational modes has been observed in the laboratory using millimeter/submillimeter direct absorption spectroscopy. The rotational spectra of two isotopically substituted species, MgD and (Mg-26)H, have been detected as well. All six hyperfine components of the N = 0 -1 transition of MgH in its v = 0 and v = 1 states have been directly measured to an accuracy of +/-50 kHz, and the five components have been observed for (Mg-26)H. The N = 0 +/-1 and N = 1 -2 transitions of MgD have also been detected. Rotational, fine structure, and hyperfine constants were determined for all species from a nonlinear least-squared fit to the data using a 2 Sigma Hamiltonian.
Fourier-transform spectrometric measurements of the N2O IR spectrum in the 900-1090 and 1580-2380/cm regions were obtained at a 0.005/cm resolution, and line frequencies of eight species for several ground state bands and hot bands are analyzed to obtain values of band centers and upper-state effective rotational constants. Several bands are reported for the first time. Least-squares fits for the 0400-0000, 0420(e)-0000, and 0510-0110 bands of the (N-14)2O-16 species suggest perturbation of the high-J levels of the upper states. Resonance interactions were noted in transitions including the 1001-1000 bands of (N-14)2O-16 and N-15N-14O-16.
Results of measured and calculated shift coefficients are presented for 170 absorption lines of H2O in five vibrational-rotational bands. The measurements have been carried out using highly sensitive laser spectrometers with a resolution of at least 0.01/cm; the calculations are based on the Anderson-Tsao-Curnutte-Frost method. Good agreement is obtained between the theoretical and experimental values of the shift coefficients of H2O lines due to N2, O2, and air pressure.