1,900 research outputs found
Putting the Organization on Wheels: Workplace Design at SEI
When a new employee joins SEI, it is an unusual experience. The new hire is given a map and sent down to a storeroom on the lower floor of the main building. There, the employee is issued a chair and desk, both on wheels, with a computer and phone on the desktop. The map shows where in the complex of nine barn-like buildings on the corporate campus in Oaks, Pennsylvania, the new hire will initially be located. The employee then rolls the desk through the buildings, into the oversized elevators designed for this purpose, past hallways filled with a provocative (and sometimes shocking) collection of emerging contemporary art
Nystr\"om methods for high-order CQ solutions of the wave equation in two dimensions
We investigate high-order Convolution Quadratures methods for the solution of
the wave equation in unbounded domains in two dimensions that rely on Nystr\"om
discretizations for the solution of the ensemble of associated Laplace domain
modified Helmholtz problems. We consider two classes of CQ discretizations, one
based on linear multistep methods and the other based on Runge-Kutta methods,
in conjunction with Nystr\"om discretizations based on Alpert and QBX
quadratures of Boundary Integral Equation (BIE) formulations of the Laplace
domain Helmholtz problems with complex wavenumbers. We present a variety of
accuracy tests that showcase the high-order in time convergence (up to and
including fifth order) that the Nystr\"om CQ discretizations are capable of
delivering for a variety of two dimensional scatterers and types of boundary
conditions
Single-Walled Carbon Nanotubes as Shadow Masks for Nanogap Fabrication
We describe a technique for fabricating nanometer-scale gaps in Pt wires on
insulating substrates, using individual single-walled carbon nanotubes as
shadow masks during metal deposition. More than 80% of the devices display
current-voltage dependencies characteristic of direct electron tunneling. Fits
to the current-voltage data yield gap widths in the 0.8-2.3 nm range for these
devices, dimensions that are well suited for single-molecule transport
measurements
The Epic of Gilgamesh
The Utah State University Wind Orchestra presents The Epic of Gilgamesh.https://digitalcommons.usu.edu/music_programs/1137/thumbnail.jp
Detection of Multi-Layer and Vertically-Extended Clouds Using A-Train Sensors
The detection of mUltiple cloud layers using satellite observations is important for retrieval algorithms as well as climate applications. In this paper, we describe a relatively simple algorithm to detect multiple cloud layers and distinguish them from vertically-extended clouds. The algorithm can be applied to coincident passive sensors that derive both cloud-top pressure from the thermal infrared observations and an estimate of solar photon pathlength from UV, visible, or near-IR measurements. Here, we use data from the A-train afternoon constellation of satellites: cloud-top pressure, cloud optical thickness, the multi-layer flag from the Aqua MODerate-resolution Imaging Spectroradiometer (MODIS) and the optical centroid cloud pressure from the Aura Ozone Monitoring Instrument (OMI). For the first time, we use data from the CloudSat radar to evaluate the results of a multi-layer cloud detection scheme. The cloud classification algorithms applied with different passive sensor configurations compare well with each other as well as with data from CloudSat. We compute monthly mean fractions of pixels containing multi-layer and vertically-extended clouds for January and July 2007 at the OMI spatial resolution (l2kmx24km at nadir) and at the 5kmx5km MODIS resolution used for infrared cloud retrievals. There are seasonal variations in the spatial distribution of the different cloud types. The fraction of cloudy pixels containing distinct multi-layer cloud is a strong function of the pixel size. Globally averaged, these fractions are approximately 20% and 10% for OMI and MODIS, respectively. These fractions may be significantly higher or lower depending upon location. There is a much smaller resolution dependence for fractions of pixels containing vertically-extended clouds (approx.20% for OMI and slightly less for MODIS globally), suggesting larger spatial scales for these clouds. We also find higher fractions of vertically-extended clouds over land as compared with ocean, particularly in the tropics and summer hemisphere
Multi-sensor Cloud Retrieval Simulator and Remote Sensing from Model Parameters
In this paper we describe a general procedure for calculating synthetic sensor radiances from variable output from a global atmospheric forecast model. In order to take proper account of the discrepancies between model resolution and sensor footprint, the algorithm takes explicit account of the model subgrid variability, in particular its description of the probability density function of total water (vapor and cloud condensate.) The simulated sensor radiances are then substituted into an operational remote sensing algorithm processing chain to produce a variety of remote sensing products that would normally be produced from actual sensor output. This output can then be used for a wide variety of purposes such as model parameter verification, remote sensing algorithm validation, testing of new retrieval methods and future sensor studies.We show a specific implementation using the GEOS-5 model, the MODIS instrument and the MODIS Adaptive Processing System (MODAPS) Data Collection 5.1 operational remote sensing cloud algorithm processing chain (including the cloud mask, cloud top properties and cloud optical and microphysical properties products). We focus on clouds because they are very important to model development and improvement
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