3,136 research outputs found
Contemporary Business -13/E.
Opening new doors of possibility can be difficult. CONTEMPORARY BUSINESS 13e gives students the business language they need to feel confident in taking the first steps toward becoming successful business majors and successful businesspeople.
As with every good business, though, the patterns of innovation and excellence established at the beginning remain steadfast. The goals and standards of Boone & Kurtz, Contemporary Business, remain intact and focused on excellence, as always. We present to you a text and supplement package that will not only move your COURSE FORWARD FASTER but also move your STUDENTS FORWARD FASTER into the new business era
A Solar-Hydrogen Energy Conversion Scheme for Agricultural Use
A solar energy activated system is presented which can produce hydrogen and hydrogen-derived fuels (methanol) for use on farms. The device, named solar-kine , also can produce fertilizer (anhydrous ammonia) as a byproduct of the hydrogen. A cost analysis shows that solar-kine may be mass-producible and sold to farmers for between 14,700. This is equivalent to giving the fanner energy at a price of 3.66 per million BTU\u27s (in 1974 dollars). Presently (Spring, 1974) regular gasoline used in tractors at 43Âą per gallon, represents a cost to the farmer of $3.77 per million BTU\u27s. As oil-based fuels increase in price in the next few years, solar-kine may represent a reasonable alternative to keep food prices down.
The solar-kine system uses concentrated solar energy which can be converted into a high-density electric current by means of a thermionic heat engine. The rejected heat and electric current from the thermionic converter is supplied to an electrolysis cell which, in turn, produces hydrogen and oxygen gas. Chemical process equipment will use the hydrogen and oxygen to produce a methanol (CH3OH) fuel supply for internal combustion engines used on farm machines. The hydrogen can also be used to manufacture ammonia, ammonium nitrate (NH4NO3), and ammonium sulfate [(NH4)2SO4)] fertilizers. The following materials can be produced which are useful to the farmer: a) hydrogen gas, b) oxygen gas, c) liquid tractor fuel, d) fertilizer, e) ammonia, f) electricity, and e) heat energy
We feel that any unconventional energy system, such as solar-kine, must interface and serve the conventional use of fuel energy if it is to have lasting merits. This is why we feel that it is desirable to have the complete conversion of solar energy into a liquid fuel that is safe to handle and store, and which also can be used in any conventional fossil-fuel burning system with minimum modifications.
Solar energy is compatible with our environment; it is free, and its supply cannot be exhausted. It is also available at any geographic location without requiring transportation to the user\u27s site (See Fig. 2). Its major advantage over fossil fuel comes from the fact that it does not add any net heat content to the earth [5,6].
A small on-site energy system is best for the farmer because,
a) It can be mass produced at 106 or more, units per year,b) Power levels needed by farms are low, 100-500 KW, c)Farm energy is used over a large geographical area, d)The main source of energy (the sun) is everywhere available,e) Heat rejected from the heat engine (thermionic) is used in other portions of the system to increase overall efficiency, and may be used in part to heat buildings,f) The farmer would be energy-independent from the price and supply undulations of the industrial complex,g) Legal considerations which regulate the large energy distribution systems would not apply, or affect, the proposed system as used by the farmer,h) Last, and possibly most important, the farmer would have a dependable fuel supply at the lowest possible cost. In the future, the proposed system will supply energy at a cost much lower than petroleum-derived energy
Feeding AGN: new results from the NUGA survey
The NUGA project is a high-resolution (0.5''-1'') CO survey of low luminosity
AGN including the full sequence of activity types (Seyferts, LINERs and
transition objects). NUGA aims to systematically study the different mechanisms
for gas fueling of AGNs in the Local Universe. In this paper we discuss the
latest results of this recently completed survey, which now includes newly
acquired subarcsec resolution observations for all targets of the sample. The
large variety of circumnuclear disk morphologies found in NUGA galaxies (m=1,
m=2 and stochastic instabilities) is a challenging result that urges the
refinement of current dynamical models. In this paper we report on new results
obtained in 4 study cases for NUGA: NGC4826, NGC7217, NGC4579 and NGC6951Comment: 4 pages, 2 figures. Contributed talk to appear in "The Interplay
among Black Holes, Stars and ISM in Galactic Nuclei," Proc. IAU 222 (Gramado,
Brazil), eds. Th. Storchi Bergmann, L.C. Ho, H.R. Schmit
ALMA reveals the feeding of the Seyfert 1 nucleus in NGC 1566
We report ALMA observations of CO(3-2) emission in the Seyfert 1 galaxy NGC
1566, at a spatial resolution of 25 pc. Our aim is to investigate the
morphology and dynamics of the gas inside the central kpc, and to probe nuclear
fueling and feedback phenomena. NGC 1566 has a nuclear bar of 1.7 kpc radius
and a conspicuous grand design spiral starting from this radius. The ALMA field
of view, of diameter 0.9 kpc, lies well inside the nuclear bar and reveals a
molecular trailing spiral structure from 50 to 300~pc in size, which is
contributing to fuel the nucleus, according to its negative gravity torques.
The spiral starts with a large pitch angle from the center and then winds up
in a pseudo-ring at the inner Lindblad resonance (ILR) of the nuclear bar.
This is the first time that a trailing spiral structure is clearly seen
driving the gas inwards inside the ILR ring of the nuclear bar. This phenomenon
shows that the massive central black hole has a significant dynamical influence
on the gas, triggering its fueling.
The gaseous spiral is well correlated with the dusty spiral seen through
extinction in HST images, and also with a spiral feature emitting 0.87mm
continuum. This continuum emission must come essentially from cold dust heated
by the interstellar radiation field. The HCN(4-3) and HCO+(4-3) lines were
simultaneously mapped and detected in the nuclear spiral. The HCO+(4-3) line is
3 times stronger than the HCN(4-3), as expected when star formation excitation
dominates over active galactic nucleus (AGN) heating. The CO(3-2)/HCO+(4-3)
integrated intensity ratio is \sim 100.
The molecular gas is in remarkably regular rotation, with only slight
non-circular motions at the periphery of the nuclear spiral arms. These
perturbations are quite small, and no outflow nor AGN feedback is detected.Comment: 11 pages, 16 figures, accepted in Astronomy and Astrophysic
Molecular gas in NUclei of GAlaxies (NUGA) XV. Molecular gas kinematics in the inner 3kpc of NGC6951
Within the NUclei of GAlaxies project we have obtained IRAM PdBI and 30m
12CO(1-0) and 12CO(2-1) observations of the spiral galaxy NGC 6951. Previous
work shows that there is indirect evidence of gas inflow from 3 kpc down to
small radii: a large-scale stellar bar, a prominent starburst ring (r~580 pc)
and a LINER/Seyfert 2 nucleus. In this paper we study the gas kinematics as
traced by the CO line emission in detail. We quantify the influence of the
large-scale stellar bar by constructing an analytical model of the evolution of
gas particles in a barred potential. From this model gravitational torques and
mass accumulation rates are computed. We compare our model-based gravitational
torque results with previous observationally-based ones. The model also shows
that the large-scale stellar bar is indeed the dominant force for driving the
gas inward, to the starburst ring. Inside the ring itself a nuclear stellar
oval might play an important role. Detailed analysis of the CO gas kinematics
there shows that emission arises from two co-spatial, but kinematically
distinct components at several locations. The main emission component can
always be related to the overall bar-driven gas kinematics. The second
component exhibits velocities that are larger than expected for gas on stable
orbits, has a molecular gas mass of 1.8x10^6Msun, is very likely connected to
the nuclear stellar oval, and is consistent with inflowing motion towards the
very center. This may form the last link in the chain of gas inflow towards the
active galactic nucleus in NGC 6951.Comment: 17 pages, accepted by A&A (17 feb 2011
ALMA observations of feeding and feedback in nearby Seyfert galaxies: an AGN-driven outflow in NGC 1433
We report ALMA observations of CO(3-2) emission in the Seyfert 2
double-barred galaxy NGC1433, at the unprecedented spatial resolution of
0.5"=24 pc. Our aim is to probe AGN feeding and feedback phenomena through the
morphology and dynamics of the gas inside the central kpc. The CO map, which
covers the whole nuclear region (nuclear bar and ring), reveals a nuclear
gaseous spiral structure, inside the nuclear ring encircling the nuclear
stellar bar.
This gaseous spiral is well correlated with the dusty spiral seen in Hubble
Space Telescope images. The nuclear spiral winds up in a pseudo-ring at 200 pc
radius, which might correspond to the inner ILR. Continuum emission is detected
at 0.87 mm only at the very centre, and its origin is more likely thermal dust
emission than non-thermal emission from the AGN. It might correspond to the
molecular torus expected to exist in this Seyfert 2 galaxy. The HCN(4-3) and
HCO+(4-3) lines were observed simultaneously, but only upper limits are
derived, with a ratio to the CO(3-2) line lower than 1/60 at 3sigma, indicating
a relatively low abundance of very dense gas. The kinematics of the gas over
the nuclear disk reveal rather regular rotation only slightly perturbed by
streaming motions due to the spiral; the primary and secondary bars are too
closely aligned with the galaxy major or minor axis to leave a signature in the
projected velocities. Near the nucleus, there is an intense high-velocity CO
emission feature redshifted to 200 km/s (if located in the plane), with a
blue-shifted counterpart, at 2" (100 pc) from the centre. While the CO spectra
are quite narrow in the centre, this wide component is interpreted as an
outflow involving a molecular mass of 3.6 10^6 Mo and a flow rate 7 Mo/yr. The
flow could be in part driven by the central star formation, but is mainly
boosted by the AGN through its wind or radio jets.Comment: 11 pages, 9 figures, Accepted in Astronomy and Astrophysic
NUGA: the IRAM survey of AGN spiral hosts
The NUclei of GAlaxies (NUGA) project is a combined effort to carry out a
high-resolution (<1'') interferometer CO survey of a sample of 12 nearby AGN
spiral hosts, using the IRAM array. We map the distribution and dynamics of
molecular gas in the inner 1 kpc of the nuclei with resolutions of 10-50 pc,
and study the mechanisms for gas fueling of the different low-luminosity AGN.
First results show evidence for the occurrence of strong m=1 gas instabilities
in Seyferts. NUGA maps allow us to address the origin/nature of m=1 modes and
their link with m=2 modes and acoustic instabilities, present in other targets.Comment: 1 gzipped tar file containing 1 Latex file + 3 eps figures.
Proceedings of ''Active Galactic Nuclei: from Central Engine to Host
Galaxy'', meeting held in Meudon, France, July 23-27, 2002, Eds.: S. Collin,
F. Combes and I. Shlosman. To be published in ASP Conference Serie
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