17,758 research outputs found
Cogeneration Technology Alternatives Study (CTAS). Volume 1: Summary
Various advanced energy conversion systems that can use coal or coal-derived fuels for industrial cogeneration applications were compared to provide information needed by DOE to establish research and development funding priorities for advanced-technology systems that could significantly advance the use of coal or coal-derived fuels in industrial cogeneration. Steam turbines, diesel engines, open-cycle gas turbines, combined cycles, closed-cycle gas turbines, Stirling engines, phosphoric acid fuel cells, molten carbonate fuel cells, and thermionics were studied with technology advancements appropriate for the 1985-2000 time period. The various advanced systems were compared and evaluated for wide diversity of representative industrial plants on the basis of fuel energy savings, annual energy cost savings, emissions savings, and rate of return on investment as compared with purchasing electricity from a utility and providing process heat with an on-site boiler. Also included in the comparisons and evaluations are results extrapolated to the national level
A note on the comparison of three near infrared reflectance spectroscopy calibration strategies for assessing herbage quality of ryegrass
peer-reviewedPerennial ryegrass (n = 1,836), Italian ryegrass (n = 137) and hybrid ryegrass (n =
103) herbage was taken from harvested plots from the Irish national variety evaluation
scheme and analysed for in vitro dry matter digestibility, water soluble carbohydrate
concentration, crude protein concentration and buffering capacity. Spectral data were
obtained using near infrared reflectance spectroscopy and three calibration strategies
(global, species-specific or local) were utilised to relate the reference values to the
spectral data. The local strategy generally provided the poorest estimation of herbage
composition, with global and species-specific calibration strategies producing similarly
accurate estimates of each quality trait. The higher accuracy and easier maintenance of
the global strategy make it the recommended calibration method for analysing quality
of ryegrass.Department of Agriculture, Food and the
Marine Research Stimulus Fund (07 526
Optically-pumped saturable absorber for fast switching between continuous-wave and passively mode-locked regimes of a Nd:YVO4 laser
We report on the fast (~50 μs) remote-controlled switching between continuous-wave (cw), cw mode-locked (ML) and Q-switched ML modes of operation of a Nd:YVO4 laser using an optically-pumped saturable absorber (SA). Pulses as short as 40 ps with an average output power of 0.5 W are obtained in cw ML regime
Quantum size effect in Pb(100) films: the role of symmetry and implication for film growth
We show from density-functional calculations that Pb(100) thin films exhibit
quantum size effect with a bilayer periodicity in film energies, film
relaxations, and work functions, which originate from different symmetry of the
stacking geometry of odd and even layer films. The bilayer periodicity of the
film energy is argued to survive on a semiconductor substrate, which should
allow the growth of ``magically'' thick even-layer Pb(100) films. Furthermore,
it is found that the quantum well states in a simple metal film can be
classified into -bonded and -bonded states, which quantize
independently
Finite momentum condensation in a pumped microcavity
We calculate the absorption spectra of a semiconductor microcavity into which
a non-equilibrium exciton population has been pumped. We predict strong peaks
in the spectrum corresponding to collective modes analogous to the Cooper modes
in superconductors and fermionic atomic gases. These modes can become unstable,
leading to the formation of off-equilibrium quantum condensates. We calculate a
phase diagram for condensation, and show that the dominant instabilities can be
at a finite momentum. Thus we predict the formation of inhomogeneous
condensates, similar to Fulde-Ferrel-Larkin-Ovchinnikov states.Comment: 7 pages, 4 figures, updated to accepted versio
Sea-surface circulation, sediment transport, and marine mammal distribution, Alaska continental shelf
There are no author-identified significant results in this report
Comparison of herbage yield, nutritive value and ensilability traits of three ryegrass species evaluated for the Irish Recommended List
peer-reviewedThis study examined 169 of the newest varieties of three ryegrass species, perennial (Lolium perenne L.), Italian (Lolium multiflorum Lam.) and hybrid (Lolium boucheanum Kunth), from Recommended List trials in Ireland. The traits examined were yield, dry matter concentration, three nutritive value traits (in vitro dry matter digestibility, water-soluble carbohydrate on a dry matter basis and crude protein concentration) and two ensilability traits (buffering capacity and water soluble carbohydrate concentration on an aqueous phase basis). Varietal monocultures of each species underwent a six cut combined simulated grazing and silage management in each of two years following sowing. Perennial ryegrass yielded less than both other species in one-year-old swards, but less than only Italian ryegrass in two-year-old swards, but generally had the higher in vitro dry matter digestibility and crude protein values. Italian ryegrass displayed the most favourable ensilability characteristics of the three species with perennial ryegrass less favourable and hybrid ryegrass intermediate. Overall, despite the high yields and favourable nutritive value and ensilability traits recorded, the general differences between the three ryegrass species studied were in line with industry expectations. These findings justify assessing the nutritive value and ensilability of ryegrass species, in addition to yield, to allow farmers select species that match farming enterprise requirements.We acknowledge the Department of Agriculture, Food and the Marine for funding provided through the Research Stimulus Fund (07 526
Optical binding mechanisms: a conceptual model for Gaussian beam traps
Optical binding interactions between laser-trapped spherical microparticles
are familiar in a wide range of trapping configurations. Recently it has been
demonstrated that these experiments can be accurately modeled using Mie
scattering or coupled dipole models. This can help confirm the physical
phenomena underlying the inter-particle interactions, but does not necessarily
develop a conceptual understanding of the effects that can lead to future
predictions. Here we interpret results from a Mie scattering model to obtain a
physical description which predict the behavior and trends for chains of
trapped particles in Gaussian beam traps. In particular, it describes the
non-uniform particle spacing and how it changes with the number of particles.
We go further than simply \emph{demonstrating} agreement, by showing that the
mechanisms ``hidden'' within a mathematically and computationally demanding Mie
scattering description can be explained in easily-understood terms.Comment: Preprint of manuscript submitted to Optics Expres
Enzyme activity in terrestrial soil in relation to exploration of the Martian surface
Urease activity in soil is persistent for long periods under low water, low temperature, and sterile regimes, and it was suggested that some form of enzyme-protective mechanism exists in soil. Dublin soil was extracted by sonication in water followed by adding a mixture of salts. Urease activity is associated with the organo-mineral complex thus obtained and is resistant to the activities of proteolytic enzymes. Clay free soil organic matter prepared subsequently by filtration also exhibits urease activity which is resistant to proteolysis. Models consisting of enzymes with bentonite and lignin were found to mimic this resistance to proteolysis. A model system is presented which suggests both the origin and location of soil ureases and a reason for their persistence in nature
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