Extended range stress intensity factor expressions for chevron-notched short bar and short rod fracture toughness specimens
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Shannon, J. L., Jr.↗
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Mineralogical remote sensing of surface expressions of deep-seated porphyry copper deposits at Safford mining district, Arizona
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Abrams, M.↗
Diurnal movements of cotton leaves expressed as thermodynamic work and entropy changes
It is pointed out that some important agricultural crops show heliotropic leaf movements. In these species, the proclivity of leaves to orient either perpendicularly or parallel or in some combination of these positions with respect to the sun is controlled by the leaf turgor and the availability of water. Such an orientational response is particularly noticeable for cotton. Schutt et al. (1985) have detailed leaf trajectories using three angles. The present investigation applies the three-angle representation to leaf trajectory mapping and to the calculation of the phase angle 'gamma' between the individual leaf normals and the solar direction. Using gamma, the thermodynamic work and entropy functions are evaluated and used to distinguish between the behavior of water-stressed and well watered cotton canopies.
Schutt, J. B.↗
Metamorphic core complexes: Expression of crustal extension by ductile-brittle shearing of the geologic column
Metamorphic core complexes and detachment fault terranes in the American Southwest are products of stretching of continental crust in the Tertiary. The physical and geometric properties of the structures, fault rocks, and contact relationships that developed as a consequence of the extension are especially well displayed in southeastern Arizona. The structures and fault rocks, as a system, reflect a ductile-through-brittle continuum of deformation, with individual structures and faults rocks showing remarkably coordinated strain and displacement patterns. Careful mapping and analysis of the structural system has led to the realization that strain and displacement were partitioned across a host of structures, through a spectrum of scales, in rocks of progressively changing rheology. By integrating observations made in different parts of the extensional system, especially at different inferred depth levels, it has been possible to construct a descriptive/kinematic model of the progressive deformation that achieved continental crustal extension in general, and the development of metamorphic core complexes in particular.
Davis, G. H.↗
Remote express analysis of ground-layer aerosol based on laser-induced spark spectra
The creation of high-power pulsed CO2 and Nd-glass lasers enables the realization of the method for remote spectro-chemical analysis of atmospheric aerosols based on excitation of the emission spectrum of the aerosol particle atoms. A description of construction and characteristics of a spectrochemical lidar based on both Nd-glass and CO2 lasers is presented.
Zuev, V. E.↗
An asymptotic expression for the dipole oscillator strength for transitions of the He sequence
The radial integral for 1s2 1S-1s np 1P transitions of the He isoelectronic sequence is asymptotically expanded to order n exp -7 to facilitate calculations of the dipole oscillator strength for large n. The threshold differential oscillator strength values are obtained for ions up to Z = 30 within the screened hydrogenic model.
Khandelwal, G. S.↗
Comparison of results from simple expressions for MOSFET parameter extraction
In this paper results are compared from a parameter extraction procedure applied to the linear, saturation, and subthreshold regions for enhancement-mode MOSFETs fabricated in a 3-micron CMOS process. The results indicate that the extracted parameters differ significantly depending on the extraction algorithm and the distribution of I-V data points. It was observed that KP values vary by 30 percent, VT values differ by 50 mV, and Delta L values differ by 1 micron. Thus for acceptance of wafers from foundries and for modeling purposes, the extraction method and data point distribution must be specified. In this paper measurement and extraction procedures that will allow a consistent evaluation of measured parameters are discussed.
Buehler, M. G.↗
Analytical expressions for the Rosseland-mean opacity and electron scattering in stellar atmospheres
Simple analytical approximations for the calculations of the electron scattering coefficient, the Rosseland-mean opacity and the equation of state in the temperature range of 4000 to 50,000 K and the density range of 10 to the -13th to 10 to the -7th g/cu cm. These approximations are valid for a gas with 1, 0.1, and 0.01 times the solar metal abundances in LTE. The accuracy of the approximations is better than 5 percent over most of this temperature and density range.
Burger, P.↗
Penetrative convection - Parametrized expression for the growth rates
The equations determining the linear growth rate omega characterizing a convectively unstable fluid with Rayleigh number R(u) bounded below by an impenetrable free boundary and above by a convectively stable fluid with Rayleigh number R(s), are solved numerically. Using the analytical Rayleigh-Benard growth rate omega (RB) as a convenient functional form, it is possible to fit the numerical values for omega if the vertical wave number k(z) = n(pi) and the Rayleigh number R(RB) are taken to be functions of R(s), R(u), and the horizontal wave number k-perpendicular rather than n = integer as in the Rayleigh-Benard case. In addition, contrary to Rayleigh-Benard convection, in which the critical Rayleigh number is fixed, it is found that R super (cr) sub u is variable in the presence of a stable layer, (i.e., it depends on R(s)).
Savolainen, V.↗
Closed form expressions for crack mouth displacements and stress intensity factors for chevron notched short bar and short rod specimens based on experimental compliance measurements
A set of equations are presented describing certain fracture mechanics parameters for chevron notch bar and rod specimens. They are developed by fitting compliance calibration data reported earlier. The equations present the various parameters in their most useful forms. The data encompass the entire range of the specimen geometries most commonly used. Their use will facilitate the testing and analysis of brittle metals, ceramics, and glasses.
Bubsey, R. T.↗
Interaction of various mechanical activity models in regulation of myosin heavy chain isoform expression
The purpose of this study was to determine the effects of a novel combination of mechanical activity paradigms on the isomyosin distribution in rat hindlimb muscles. Thirty female Sprague-Dawley rats were divided into five experimental groups as follows: normal control, functional overload (OV) of the plantaris, OV in conjunction with hindlimb suspension (OV-S), and a combination of OV-S and either static standing weight-bearing activity (OV-SS) or high-incline treadmill exercise (OV-SE). OV of the plantaris resulted in significant hypertrophy and significant fast-to-slow isomyosin shifts. These changes were completely inhibited by the addition of hindlimb suspension (OV-S). Also, neither of the two weight-bearing regimes (OV-SS and OV-SE) was able to attenuate the suspension-induced atrophy. In the vastus intermedius and vastus lateralis, however, OV-SS was able to partially retard the atrophy associated with suspension. In both the plantaris and vastus intermedius, only OV-SS was able to partially reverse the slow-to-fast isomyosin transitions associated with suspension. These results suggest that the type of mechanical activity is important in determining adaptation to altered loading conditions, with OV-SS appearing more effective than OV-SE in reversing the effects of unweighting.
Diffee, Gary M.↗
Significance of the expression C(sub L)(exp 3)/C(sub D)(exp 2)
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Von Sanden, H↗
Charts expressing the time, velocity, and altitude relations for an airplane diving in a standard atmosphere
In this report charts are given showing the relation between time, velocities, and altitude for airplanes having various terminal velocities diving in a standard atmosphere. The range of starting altitudes is from 8,000 to 32,000 feet, and the terminal velocities vary from 150 to 550 miles per hour. A comparison is made between an experimental case and the results obtained from the charts. Examples pointing out the use of the charts are included.
Pearson, H A↗
Expressions for measuring the accuracy of approximate solutions to compressible flow through cascades of blades with examples of use
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Sinnette, John T↗
Vegetation species composition and canopy architecture information expressed in leaf water absorption measured in the 1000 nm and 2200 spectral region by an imaging spectrometer
Plant species composition and plant architectural attributes are critical parameters required for the measuring, monitoring, and modeling of terrestrial ecosystems. Remote sensing is commonly cited as an important tool for deriving vegetation properties at an appropriate scale for ecosystem studies, ranging from local to regional and even synoptic scales. Classical approaches rely on vegetation indices such as the normalized difference vegetation index (NDVI) to estimate biophysical parameters such as leaf area index or intercepted photosynthetically active radiation (IPAR). Another approach is to apply a variety of classification schemes to map vegetation and thus extrapolate fine-scale information about specific sites to larger areas of similar composition. Imaging spectrometry provides additional information that is not obtainable through broad-band sensors and that may provide improved inputs both to direct biophysical estimates as well as classification schemes. Some of this capability has been demonstrated through improved discrimination of vegetation, estimates of canopy biochemistry, and liquid water estimates from vegetation. We investigate further the potential of leaf water absorption estimated from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data as a means for discriminating vegetation types and deriving canopy architectural information. We expand our analysis to incorporate liquid water estimates from two spectral regions, the 1000-nm region and the 2200-nm region. The study was conducted in the vicinity of Jasper Ridge, California, which is located on the San Francisco peninsula to the west of the Stanford University campus. AVIRIS data were acquired over Jasper Ridge, CA, on June 2, 1992, at 19:31 UTC. Spectra from three sites in this image were analyzed. These data are from an area of healthy grass, oak woodland, and redwood forest, respectively. For these analyses, the AVIRIS-measured upwelling radiance spectra for the entire Jasper Ridge scene were transformed to apparent surface reflectance using a radiative transfer code-based inversion algorithm.
Green, Robert O.↗
Euler potentials of current-free fields expressed in spherical harmonics
Given a magnetic field B = -del(vector differential operator)(sub gamma) with gamma expanded in spherical harmonics, it is shown that analytic Euler potentials may be derived for B if gamma is asymmetrical but contains only the contribution of a single index n. This work generalizes a result for sectorial harmonics with n = m, derived by Willis and Gardiner (1988).
Stern, David P.↗
A Station Tethered Express Payload System (STEPS)
Most capsules designed to return payloads from earth orbit use rockets for deorbit. They have modest payload mass & volume fractions. Active attitude control raises costs, and the deorbit rocket imposes risks which increase development and operational costs. This note describes an alternative concept now being developed under NASA funding. It uses a tether to both deorbit and orient the capsule. This allows simultaneous reduction of capsule complexity, cost, loads, hazards, and reentry errors. The flight of SEDS-1 in 1993 proved out the basic concepts. A 20 km tether slung a 26 kg payload back to earth from a 74O x 19O km orbit, accurately enough for a pre-positioned observer to videotape the reentry. As air drag built up just before reentry, the tether was blown back and became a kite-tail, with tension increasing as predicted before flight. The tether was still attached at approx. 110 km, when telemetry was lost.
Carroll, Joseph A.↗
Receptor Expression in Rat Skeletal Muscle Cell Cultures
One on the most persistent problems with long-term space flight is atrophy of skeletal muscles. Skeletal muscle is unique as a tissue in the body in that its ability to undergo atrophy or hypertrophy is controlled exclusively by cues from the extracellular environment. The mechanism of communication between muscle cells and their environment is through a group of membrane-bound and soluble receptors, each of which carries out unique, but often interrelated, functions. The primary receptors include acetyl choline receptors, beta-adrenergic receptors, glucocorticoid receptors, insulin receptors, growth hormone (i.e., somatotropin) receptors, insulin-like growth factor receptors, and steroid receptors. This project has been initiated to develop an integrated approach toward muscle atrophy and hypertrophy that takes into account information on the populations of the entire group of receptors (and their respective hormone concentrations), and it is hypothesized that this information can form the basis for a predictive computer model for muscle atrophy and hypertrophy. The conceptual basis for this project is illustrated in the figure below. The individual receptors are shown as membrane-bound, with the exception of the glucocorticoid receptor which is a soluble intracellular receptor. Each of these receptors has an extracellular signalling component (e.g., innervation, glucocorticoids, epinephrine, etc.), and following the interaction of the extracellular component with the receptor itself, an intracellular signal is generated. Each of these intracellular signals is unique in its own way; however, they are often interrelated.
Young, Ronald B.↗