68,195 research outputs found
Report of the Terrestrial Bodies Science Working Group. Volume 6: The asteroids
Earth-based astronomical observations and laboratory analysis of meteorites provide the only scientific data available on asteroids. These data are summarized and subjects for future investigations are explored. The measurements required for potential missions are discussed and concepts for a multi-asteroid rendezvous mission in the mid-1980's are outlined
DYNAMICS AND PRICE VOLATILITY IN FARM-RETAIL LIVESTOCK PRICE RELATIONSHIPS
This study uses an error correction model (ECM) to investigate dynamics in farm-retail price relationships. The ECM is a more general method of incorporating dynamics and the long-run, steady-state relationships between farm and retail prices than has been used to data. Monthly data for beef and pork are used to test the time-series properties for the ECM specification. The model is extended to study price volatility through the generalized autoregressive conditional heteroskedasticity (GARCH) process. Accommodation of the GARCH process provides a useful way of analyzing both mean and variance effects of policy or market structure changes.Demand and Price Analysis, Livestock Production/Industries,
Coolant passage heat transfer with rotation
In current and advanced gas turbine engines, increased speeds, pressures and temperatures are used to reduce specific fuel consumption and increase thrust/weight ratios. Hence, the turbine airfoils are subjected to increased heat loads escalating the cooling requirements to satisfy life goals. The efficient use of cooling air requires that the details of local geometry and flow conditions be adequately modeled to predict local heat loads and the corresponding heat transfer coefficients. The objective of this program is to develop a heat transfer and pressure drop data base, computational fluid dynamic techniques and correlations for multi-pass rotating coolant passages with and without flow turbulators. The experimental effort is focused on the simulation of configurations and conditions expected in the blades of advanced aircraft high pressure turbines. With the use of this data base, the effects of Coriolis and buoyancy forces on the coolant side flow can be included in the design of turbine blades
Tip-gating Effect in Scanning Impedance Microscopy of Nanoelectronic Devices
Electronic transport in semiconducting single-wall carbon nanotubes is
studied by combined scanning gate microscopy and scanning impedance microscopy
(SIM). Depending on the probe potential, SIM can be performed in both invasive
and non-invasive mode. High-resolution imaging of the defects is achieved when
the probe acts as a local gate and simultaneously an electrostatic probe of
local potential. A class of weak defects becomes observable even if they are
located in the vicinity of strong defects. The imaging mechanism of tip-gating
scanning impedance microscopy is discussed.Comment: 11 pages, 3 figures, to be published in Appl. Phys. Let
Carbon nanotubes as a tip calibration standard for electrostatic scanning probe microscopies
Scanning Surface Potential Microscopy (SSPM) is one of the most widely used
techniques for the characterization of electrical properties at small
dimensions. Applicability of SSPM and related electrostatic scanning probe
microscopies for imaging of potential distributions in active micro- and
nanoelectronic devices requires quantitative knowledge of tip surface contrast
transfer. Here we demonstrate the utility of carbon-nanotube-based circuits to
characterize geometric properties of the tip in the electrostatic scanning
probe microscopies (SPM). Based on experimental observations, an analytical
form for the differential tip-surface capacitance is obtained.Comment: 14 pages, 4 figure
Disk resolved studies of the optical properties and physical nature of the surfaces of the outer planet satellites
The spatially resolved albedo, color, compaction state, roughness, and constituent particle sizes of the surfaces of the satellites of Saturn, Uranus, and Jupiter provide important constraints in understanding the geologic evolution and relevant exogenic processes operating in these satellite systems. Some details of observations are given
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