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Sensitivity of surface characteristics on the simulation of wind-blown-dust source in North America
Park, S.H.,Gong, S.L.,Gong, W.,Makar, P.A.,Moran, M.D.,Stroud, C.A.,Zhang, J. Pergamon Press ; Elsevier [distribution] 2009 Atmospheric environment Vol.43 No.19
Recently, a wind-blown-dust-emission module has been built based on a state-of-the-art wind erosion theory and evaluated in a regional air-quality model to simulate a North American dust storm episode in April 2001 (see Park, S.H., Gong, S.L., Zhao, T.L., Vet, R.J., Bouchet, V.S., Gong, W., Makar, P.A., Moran, M.D., Stroud, C., Zhang, J. 2007. Simulation of entrainment and transport of dust particles within North America in April 2001 (''Red Dust episode''). J. Geophys. Res. 112, D20209, doi:10.1029/2007JD008443). A satisfactorily detailed assessment of that module, however, was not possible because of a lack of information on some module inputs, especially soil moisture content. In this paper, the wind-blown-dust emission was evaluated for two additional dust storms using improved soil moisture inputs. The surface characteristics of the wind-blown-dust source areas in southwestern North America were also investigated, focusing on their implications for wind-blown-dust emissions. The improved soil moisture inputs enabled the sensitivity of other important surface characteristics, the soil grain size distribution and the land-cover, to dust emission to be investigated with more confidence. Simulations of the two 2003 dust storm episodes suggested that wind-blown-dust emissions from the desert areas in southwestern North America are dominated by emissions from dry playas covered with accumulated alluvial deposits whose particle size is much smaller than usual desert sands. As well, the source areas in the northwestern Texas region were indicated to be not desert but rather agricultural lands that were ''activated'' as a wind-blown-dust sources after harvest. This finding calls for revisions to the current wind-blown-dust-emission module, in which ''desert'' is designated to be the only land-cover category that can emit wind-blown dust.
S-I-S Josephson junction with a correlated insulator below its S-I transition
Porter, C.D.,Kim, K.,Stroud, D. North-Holland 2014 Physica. C, Superconductivity Vol.498 No.-
We consider a Josephson junction composed of two superconducting (S) regions separated by an insulating (I) region, but with the special property that the S and the I regions are superconducting films respectively above and below the superconducting-insulating (S-I) transition. To calculate the properties of this junction, we describe the system using an inhomogeneous quantum rotor Hamiltonian with a coupling energy J and spatially varying charging energy U. The ratio J/U is chosen so that it is above the critical value for an S-I transition in the two superconducting regions, but below it in the insulating regime. Using both mean-field theory and perturbation theory, we show that the phase order parameter is finite in the S region and decays exponentially into the I region. Thus, the order parameter, which would be zero in the I region in isolation, is instead rendered nonzero by the adjacent S region, because of a proximity effect. As a result, there is a nonzero coupling energy between the two S regions. We show, using both mean-field theory and a quantum Monte Carlo calculation, that the phase stiffness constant, or helicity modulus, of this junction is nonzero, and falls off exponentially with separation of the two superconductors. We also analytically estimate the dependence of the coupling energy on the properties of the S and I regions, and suggest an analogy with conventional S-N-S junctions. Our results support the conclusion that this S-I-S sandwich structure, with a correlated insulating region, can be viewed as a single effective Josephson junction.
A roadmap for implementing new manufacturing technology based on STEP-NC
Cha, J. M.,Suh, S. H.,Hascoet, J. Y.,Stroud, I. Springer Science + Business Media 2016 Journal of Intelligent Manufacturing Vol.27 No.5
<P>Manufacturing is changing. New ideas of control, the maturity of CAM techniques and computer technology have enabled the definition of an advanced machine tool control standard, STEP-NC. STEP-NC is one part of a larger manufacturing picture with links to different manufacturing applications using the STEP suite of standards. STEP-NC is the key to a door behind which there is a rich field of research on manufacturing techniques and opportunities for lean, intelligent and flexible manufacturing. The problem is to pass through that door. Many potential users are waiting for a lead from control developers. Control developers are waiting for market interest. Existing legacy machinery and investment in traditional machining add inertia. Instead of having a clear development path, manufacturing has become something of a Gordian knot waiting to be disentangled. New research projects are addressing these issues as well, but this paper takes a different route in showing how strategic planning can lead to adoption of the new techniques in a phased way, a so-called 'Roadmap'. The contribution of this paper is the manner in which the overall task of implementation has been subdivided into tasks and phases to achieve the introduction of the new technology.</P>
Effects of black carbon aging on air quality predictions and direct radiative forcing estimation
PARK, S.H.,GONG, S.L.,BOUCHET, V.S.,GONG, W.,MAKAR, P.A.,MORAN, M.D.,STROUD, C.A.,ZHANG, J. Blackwell Publishing Ltd 2011 Tellus. Series B, Chemical and physical meteorolog Vol.63 No.5
<P><B>ABSTRACT</B></P><P>An aging scheme for black carbon (BC) aerosol was implemented into a regional air‐quality forecast model to study the impact of BC aging on air quality predictions. Three different assumptions for the mixing state of BC—external mixture, internal mixture and gradual aging—were used to simulate the distribution of BC particles over North America in April 2002. Cloud –condensation nuclei number and BC wet deposition rate increased significantly and BC mass column loading decreased as a result of BC aging. With the gradual aging process incorporated into the model, the comparison of ground level BC concentration predictions with surface observations was slightly improved. Estimation of the average direct radiative forcing of BC over the spatial domain of this study showed that the factor of direct forcing enhancement by BC aging was much smaller than the mixing state effect factor. The effect of increased wet deposition due to aging compensated partially for the effect of increased absorbance suggesting that the change in the hygroscopic properties of BC due to aging must be taken into account to quantify accurately the effect of BC aging on climate.</P>
Comparison of Continuous and Filter-Based Carbon Measurements at the Fresno Supersite
Park, Kihong,Chow, Judith C.,Watson, John G.,Trimble, Dana L.,Doraiswamy, Prakash,Park, Kihong,Arnott, W. Pat,Stroud, Kenneth R.,Bowers, Kenneth,Bode, Richard,Petzold, Andre,Hansen, Anthony D.A. Informa UK (TaylorFrancis) 2006 Journal of the Air & Waste Management Association Vol.56 No.4
Magnetism in Single Metalloorganic Complexes Formed by Atom Manipulation
Choi, T.,Badal, M.,Loth, S.,Yoo, J.-W.,Lutz, C. P.,Heinrich, A. J.,Epstein, A. J.,Stroud, D. G.,Gupta, J. A. American Chemical Society 2014 NANO LETTERS Vol.14 No.3
<P>The magnetic properties of molecular structures can be tailored by chemical synthesis or bottom-up assembly at the atomic scale. We used scanning tunneling microscopy to study charge and spin transfer in individual complexes of transition metals with the charge acceptor, tetracyanoethylene (TCNE). The complexes were formed on a thin insulator, Cu<SUB>2</SUB>N on Cu(100), by manipulation of individual atoms and molecules. The Cu<SUB>2</SUB>N layer decouples the complexes from Cu electron density, enabling direct imaging of the TCNE molecular orbitals as well as spin-flip inelastic electron tunneling spectroscopy. Results were obtained at low temperature down to 1 K and in magnetic fields up to 7 T in order to resolve splitting of spin states in the complexes. We also performed spin-polarized density functional theory calculations to compare with the experimental data. Our results indicate that charge transfer to TCNE leads to a change in spin magnitude, Kondo resonance, and magnetic anisotropy for the metal atoms.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-3/nl404054v/production/images/medium/nl-2013-04054v_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl404054v'>ACS Electronic Supporting Info</A></P>