787 research outputs found
A monostrain test apparatus
Test apparatus is designed for determining tensile strength, modulus of elasticity, elongation, and thermal coefficient of contraction or expansion of uniformly shaped plastics, adhesives, and foam materials over temperature range of 700 to 90 K (800 to -300). Tests may be used in design quality control, and in evaluation of new adhesives and plastic materials
Right Angle Electrical Connector and Insertion Tool Therefor
Disclosed is a multi-row right angle connector and a press block for installing the connector on a mounting substrate without soldering the contact pins. The connector legs comprise eye of the needle compliant interfaces that make electrical contact with the interior surfaces of the substrate\u27s plated through holes. The press block is designed for use with a four-row right angle receptacle and locates rows 2, 3, and 4 on respective true grid positions and serves as a means for transmitting force from an external press to the contact pin tails. The contact tails in rows 2, 3, and 4 have a T-shaped shoulder that is pressed into a pocket in the press block. The insertion force is applied to the pins in row 1 by a corner having a radius matching the radius of the row 1 tails
Spontaneous axisymmetry breaking of Saturn's external magnetic field
Saturn's magnetic field is remarkably axisymmetric. Its dipole axis is
inclined by less than 0.2 deg with respect to its rotation axis. Rotationally
driven convection of magnetospheric plasma breaks the axisymmetry of its
external magnetic field. Field aligned currents transfer angular momentum from
the planet to a tongue of outflowing plasma. This transfer slows the rate of
rotation of the ionosphere relative to that of the underlying atmosphere. The
currents are the source for the non-axisymmetric components of the field. The
common rotation rates of these components and Saturn's kilometric radio (SKR)
bursts is that of the plasma near the orbit of Enceladus, and by extension the
rotation rate in the ionosphere to which this plasma is coupled. That rate
tells us nothing about the rotation rate of Saturn's deep interior. Of that we
remain ignorant. Magnetic perturbations with magnitudes similar to those
observed by Cassini are produced for Mdot ~ 10^4 g/s, a value similar to
estimates for the rate of production of plasma from Saturn's E-ring.
Enhancement of the SKR occurs in a narrow range of longitudes where the tip of
the outgoing plasma stream connects to the auroral ionosphere via field lines
that are bowed outwards by currents that supply the plasma's centripetal
acceleration. (abridged)Comment: 24 pages, 2 figures, submitted to JGR
Spatial distribution of land type in regression models of pollutant loading
This paper proposes a method to improve landscape-pollution interaction regression models through the inclusion of a variable that describes the spatial distribution of a land type with respect to the pattern of runoff within a drainage catchment. The proposed index is used as an independent variable to enhance the strength, as quantified by R² values, of regression relationships between empirical observations of in-stream pollutant concentrations and land type by considering the spatial distribution of key land-type categories within the sample point’s drainage area. We present an index that adds a new dimension of explanatory power when used in conjunction with a variable describing the proportion of the land type. We demonstrate the usefulness of this index by exploring the relationship between nitrate ( - 3 NO ) and land type within 40 drainage sub-catchments in the Ipswich River watershed, Massachusetts. Nutrient loads associated with non-point source pollution paths are related to land type within the up-stream drainage catchments of sample sites. Past studies have focused on the quantity of particular land type within a sample point’s drainage catchment. Quantifying the spatial distribution of key land-type categories in terms of location on a runoff surface can improve our understanding of the relationship between sampled - 3 NO concentrations and land type. Regressions that employ the proportion of residential and agricultural land type within catchments provide a fair fit (R² = 0.67). However, we find that a regression adding a variable that indicates the spatial distribution of residential land improves the overall relationship between instream - 3 NO measurements and associated land types (R² = 0.712). We test the sensitivity of the results with respect to variations in the surface definition in order to determine the conditions under which the spatial index variable is useful
VALIDITY OF 95% t-CONFIDENCE INTERVALS UNDER SOME TRANSECT SAMPLING STRATEGIES
Soil pH data were used to assess the capture rates of 95 % t-confidence intervals based on five different transect sampling strategies. Two different sampling methods were considered, deterministic and two-stage simple random sampling . The data used were pH readings at 15 and 30 centimeter depths from two local agricultural fields in the Manhattan, Kansas area. The data provided three distinct populations with three different distributions - skewed left, symmetric, and bimodal. The total number of transects randomly sampled was 2, 5, and 10. The total number of points sampled along each transect was 2, 7 and 14. The 95% t-confidence intervals were simulated 5000 times using five different transect sampling strategies, and the capture rates of the population mean were recorded. Box plots of the capture rates for the five transect sampling strategies were constructed and compared. In most cases the deterministic sampling method had capture rates that underestimated the 95 % confidence level, whereas the two-stage sampling strategies produced capture rates which were conservative or closer to the 95 % confidence level. The variances of the capture rates for the two-stage sampling strategies were relatively small in comparison to the deterministic sampling strategies. In conclusion, the two-stage simple random sampling method along with the Satterthwaite degrees of freedom are recommended when using transect sampling
Hot electron driven enhancement of spin-lattice coupling in 4f ferromagnets observed by femtosecond x-ray magnetic circular dichroism
Femtosecond x-ray magnetic circular dichroism was used to study the
time-dependent magnetic moment of 4 fs electrons in the ferromagnets Gd and Tb,
which are known for their different spin-lattice coupling. We observe a
two-step demagnetization with an ultrafast demagnetization time of 750 fs
identical for both systems and slower times which differ sizeably with 40 ps
for Gd and 8 ps for Tb. We conclude that spin-lattice coupling in the
electronically excited state is enhanced up to orders of magnitude compared to
equilibrium.Comment: added reference 24, clarified the meaning of photo-induced,
emphasized that XMCD probes the magnetic moment localized at 4f electron
Creating spatially-explicit lawn maps without classifying remotely-sensed imagery: The case of suburban Boston, Massachusetts, USA
Residential lawns are a dominant and growing feature of US residential landscapes, and the resource-intensive management of this landscape feature presents major potential risks to both humans and the environment. In recent years, scientists and policymakers have been increasingly calling for large-extent measures of lawns and other similar landscape features. Unfortunately, the production of such datasets using traditional, remotely sensed measurement approaches can be prohibitively expensive and time consuming. This study uses two statistical prediction methods to extrapolate the quantity and spatial distribution of residential lawns from a sample of mapped lawns in a large study area in suburban Boston, Massachusetts. The goal is to find an inexpensive, broad-coverage dataset that will provide useable estimates of landscape features in places where we do not have direct measurements of those landscape features. The first estimation method uses OLS regression in conjunction with the sample of mapped lawns and freely available US Census data representing theoretically informed social driver variables. The second, simpler, and less computationally intensive estimation method allocates the mean of the sample of mapped lawns uniformly across the study area. Both estimation methods are performed 1000 times in a Monte Carlo framework where the sample is drawn randomly each realization, to assess the sensitivity of the prediction results to the selection of CBGs in each simple random sample. The outputs of each estimation method are then compared to a reference map where the quantity and spatial allocation of lawns is known for each spatial unit of analysis. Results indicate that the OLS prediction method specified with the independent social driver variables performs better than a uniform prediction method when both are compared to the full-study area reference map
Magnetosphere-ionosphere coupling at Jupiter-like exoplanets with internal plasma sources: implications for detectability of auroral radio emissions
In this paper we provide the first consideration of magnetosphere-ionosphere
coupling at Jupiter-like exoplanets with internal plasma sources such as
volcanic moons. We estimate the radio power emitted by such systems under the
condition of near-rigid corotation throughout the closed magnetosphere, in
order to examine the behaviour of the best candidates for detection with next
generation radio telescopes. We thus estimate for different stellar X-ray-UV
(XUV) luminosity cases the orbital distances within which the ionospheric
Pedersen conductance would be high enough to maintain near-rigid corotation,
and we then consider the magnitudes of the large-scale magnetosphere-ionosphere
currents flowing within the systems, and the resulting radio powers, at such
distances. We also examine the effects of two key system parameters, i.e. the
planetary angular velocity and the plasma mass outflow rate from sources
internal to the magnetosphere. In all XUV luminosity cases studied, a
significant number of parameter combinations within an order of magnitude of
the jovian values are capable of producing emissions observable beyond 1 pc, in
most cases requiring exoplanets orbiting at distances between ~1 and 50 AU, and
for the higher XUV luminosity cases these observable distances can reach beyond
~50 pc for massive, rapidly rotating planets. The implication of these results
is that the best candidates for detection of such internally-generated radio
emissions are rapidly rotating Jupiter-like exoplanets orbiting stars with high
XUV luminosity at orbital distances beyond ~1 AU, and searching for such
emissions may offer a new method of detection of more distant-orbiting
exoplanets.Comment: 15 pages, 9 figures. In press at Mon. Not. R. Astron. So
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