6,258 research outputs found
Rural soldiers continue to account for disproportionately high share of U.S. casualties in Iraq and Afghanistan
When the nation goes to war, all Americans are expected to make sacrifices. Today\u27s rural Americans, however, have fewer job opportunities within their communities, and are joining the military at higher rates. In turn, rural communities are facing military losses in disproportionate numbers to their urban counterparts
U.S. rural soldiers account for a disproportionately high share of casualties in Iraq and Afghanistan
A study by the Carsey Institute found that among U.S. soldiers serving in Iraq and Afghanistan, those who are from rural America are dying at a higher rate than those soldiers who are from cities and suburbs. According to U.S. Department of Defense records, rural youth enlist in the military at a higher rate than urban and suburban youth and in all but eight states, soldiers from rural areas make up a disproportionately high share of the casualties
Buoyancy and thermal radiation effects for the Blasius and Sakiadis flows with a convective surface boundary condition
This study is devoted to investigate the Buoyancy and thermal radiation effects on the laminar boundary layer about a flat-plate in a uniform stream of fluid (Blasius flow), and about a moving plate in a quiescent ambient fluid (Sakiadis flow) both under a convective surface boundary condition. Using a similarity variable, the governing nonlinear partial differential equations have been transformed into a set of coupled nonlinear ordinary differential equations, which are solved numerically by using shooting technique along side with the sixth order of Runge-Kutta integration scheme and the variations of dimensionless surface temperature and fluid-solid interface characteristics for different values of Prandtl number Pr, radiation parameter NR, parameter a and the local Grashof number Grx, which characterizes our convection processes are graphed and tabulated. Quite different and interesting behaviours were encountered for Blasius flow compared with a Sakiadis flow. A comparison with previously published results on special cases of the problem shows excellent agreement
Effects of chemical reaction, thermal radiation, internal heat generation, Soret and Dufour on chemically reacting MHD boundary layer flow of heat and mass transfer past a moving vertical plate with suction/injection
In the present analysis, we study the two-dimensional, steady, incompressible electrically conducting, laminar free convection boundary layer flow of a continuously moving vertical porous plate in a chemically reactive medium in the presence of transverse magnetic field, thermal radiation, chemical reaction, internal heat generation and Dufour and Soret effect with suction/injection. The governing nonlinear partial differential equations have been reduced to the coupled nonlinear ordinary differential equations by the similarity transformations. The problem is solved numerically using shooting techniques with the sixth order Runge-Kutta integration scheme. Comparison between the existing literature and the present study were carried out and found to be in excellent agreement. The influence of the various interesting parameters on the flow and heat transfer is analyzed and discussed through graphs in detail. The values of the local Nusselt number, Skin-friction and the Sherwood number for different physical parameters are also tabulated. Comparison of the present results with known numerical results is shown and a good agreement is observed
Frustrated spin- Heisenberg magnet on a square-lattice bilayer: High-order study of the quantum critical behavior of the ---- model
The zero-temperature phase diagram of the spin-
---- model on an -stacked square-lattice
bilayer is studied using the coupled cluster method implemented to very high
orders. Both nearest-neighbor (NN) and frustrating next-nearest-neighbor
Heisenberg exchange interactions, of strengths and , respectively, are included in each layer. The two layers are
coupled via a NN interlayer Heisenberg exchange interaction with a strength
. The magnetic order parameter (viz.,
the sublattice magnetization) is calculated directly in the thermodynamic
(infinite-lattice) limit for the two cases when both layers have
antiferromagnetic ordering of either the N\'{e}el or the striped kind, and with
the layers coupled so that NN spins between them are either parallel (when
) to one another. Calculations
are performed at th order in a well-defined sequence of approximations,
which exactly preserve both the Goldstone linked cluster theorem and the
Hellmann-Feynman theorem, with . The sole approximation made is to
extrapolate such sequences of th-order results for to the exact limit,
. By thus locating the points where vanishes, we calculate
the full phase boundaries of the two collinear AFM phases in the
-- half-plane with . In particular, we provide the
accurate estimate, (), for the
position of the quantum triple point (QTP) in the region . We also
show that there is no counterpart of such a QTP in the region ,
where the two quasiclassical phase boundaries show instead an ``avoided
crossing'' behavior, such that the entire region that contains the nonclassical
paramagnetic phases is singly connected
NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 19: Computer and information technology and aerospace knowledge diffusion
To remain a world leader in aerospace, the US must improve and maintain the professional competency of its engineers and scientists, increase the research and development (R&D) knowledge base, improve productivity, and maximize the integration of recent technological developments into the R&D process. How well these objectives are met, and at what cost, depends on a variety of factors, but largely on the ability of US aerospace engineers and scientists to acquire and process the results of federally funded R&D. The Federal Government's commitment to high speed computing and networking systems presupposes that computer and information technology will play a major role in the aerospace knowledge diffusion process. However, we know little about information technology needs, uses, and problems within the aerospace knowledge diffusion process. The use of computer and information technology by US aerospace engineers and scientists in academia, government, and industry is reported
Frustrated Heisenberg antiferromagnet on the honeycomb lattice: Spin gap and low-energy parameters
We use the coupled cluster method implemented to high orders of approximation
to investigate the frustrated spin- ----
antiferromagnet on the honeycomb lattice with isotropic Heisenberg interactions
of strength between nearest-neighbor pairs, between
next-nearest-neighbor pairs, and between next-next-neareast-neighbor
pairs of spins. In particular, we study both the ground-state (GS) and
lowest-lying triplet excited-state properties in the case , in the window of the frustration
parameter, which includes the (tricritical) point of maximum classical
frustration at . We present GS results for the
spin stiffness, , and the zero-field uniform magnetic susceptibility,
, which complement our earlier results for the GS energy per spin, ,
and staggered magnetization, , to yield a complete set of accurate
low-energy parameters for the model. Our results all point towards a phase
diagram containing two quasiclassical antiferromagnetic phases, one with N\'eel
order for , and the other with collinear striped order
for . The results for both and the spin gap
provide compelling evidence for a quantum paramagnetic phase that is
gapped over a considerable portion of the intermediate region , especially close to the two quantum critical points
at and . Each of our fully independent sets of
results for the low-energy parameters is consistent with the values
and , and with
the transition at being of continuous (and probably of the
deconfined) type and that at being of first-order type
NASA/DoD Aerospace Knowledge Diffusion Research Project. Paper 31: The information-seeking behavior of engineers
Engineers are an extraordinarily diverse group of professionals, but an attribute common to all engineers is their use of information. Engineering can be conceptualized as an information processing system that must deal with work-related uncertainty through patterns of technical communications. Throughout the process, data, information, and tacit knowledge are being acquired, produced, transferred, and utilized. While acknowledging that other models exist, we have chosen to view the information-seeking behavior of engineers within a conceptual framework of the engineer as an information processor. This article uses the chosen framework to discuss information-seeking behavior of engineers, reviewing selected literature and empirical studies from library and information science, management, communications, and sociology. The article concludes by proposing a research agenda designed to extend our current, limited knowledge of the way engineers process information
NASA/DoD Aerospace Knowledge Diffusion Research Project. Paper 30: The electronic transfer of information and aerospace knowledge diffusion
Increasing reliance on and investment in information technology and electronic networking systems presupposes that computing and information technology will play a major role in the diffusion of aerospace knowledge. Little is known, however, about actual information technology needs, uses, and problems within the aerospace knowledge diffusion process. The authors state that the potential contributions of information technology to increased productivity and competitiveness will be diminished unless empirically derived knowledge regarding the information-seeking behavior of the members of the social system - those who are producing, transferring, and using scientific and technical information - is incorporated into a new technology policy framework. Research into the use of information technology and electronic networks by U.S. aerospace engineers and scientists, collected as part of a research project designed to study aerospace knowledge diffusion, is presented in support of this assertion
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