2,690 research outputs found
Performance and Emission Reduction using of Indian Pomegranate seed oil as bio-diesel
The study in made to replace the existing diesel fuel with the bio – fuels, for this fruit like Indian Pomegranate seed oil as bio – diesel is utilized. The main objective of this work is to discuss the impact of biodiesel from Pomegranate fruit seed oil bio-diesel on performance, combustion and emission characteristics diesel. In this study, the effect of bio-diesel from fruit seed oil [Indian Pomegranate seed oil] and its blends on a single cylinder Kirloskar TV-1 diesel engine were investigated.
In this work, the performance, combustion and emission analysis were conducted. The tests were performed at steady state conditions with the blend ratio of B25, B50, B75 and B100. These represent the ratio of biodiesel in the blend and the rest diesel. The aim of this investigation was to reformulate the fuel to utilize the biodiesel and its blend to enhance the fuels performance, combustion characteristic and to reduce the pollution from the engine. In this work only Indian Jujube seed oil bio-diesel is utilized for the experimental work. The experimental results reveal a marginal decrease in brake thermal efficiency when compared to that of sole fuel. In this investigation, the emission test were done with the help of AVL DI gas analyzer, in which CO, HC and NOx are appreciably reduced on the other hand smoke, CO2 have marginal increased when compared to that of sole fuel. In this work combustion analysis also made with the help of AVL combustion analyzer in which bio diesel blend shows the better result when compared with diesel
Photoionization and Photoelectric Loading of Barium Ion Traps
Simple and effective techniques for loading barium ions into linear Paul
traps are demonstrated. Two-step photoionization of neutral barium is achieved
using a weak intercombination line (6s2 1S0 6s6p 3P1, 791 nm) followed by
excitation above the ionization threshold using a nitrogen gas laser (337 nm).
Isotopic selectivity is achieved by using a near Doppler-free geometry for
excitation of the triplet 6s6p 3P1 state. Additionally, we report a
particularly simple and efficient trap loading technique that employs an
in-expensive UV epoxy curing lamp to generate photoelectrons.Comment: 5 pages, Accepted to PRA 3/20/2007 -fixed typo -clarified figure 3
caption -added reference [15
Kinetic pinning and biological antifreezes
Biological antifreezes protect cold-water organisms from freezing. An example
are the antifreeze proteins (AFPs) that attach to the surface of ice crystals
and arrest growth. The mechanism for growth arrest has not been heretofore
understood in a quantitative way. We present a complete theory based on a
kinetic model. We use the `stones on a pillow' picture. Our theory of the
suppression of the freezing point as a function of the concentration of the AFP
is quantitatively accurate. It gives a correct description of the dependence of
the freezing point suppression on the geometry of the protein, and might lead
to advances in design of synthetic AFPs.Comment: 4 pages, 4 figure
The Absorption Signatures of Dwarf Galaxies: The z=1.04 Multicloud Weak MgII Absorber toward PG 1634+706
We analyze high resolution spectra of a multi--cloud weak [defined as
W_r(MgII) < 0.3 A] absorbing system along the line of sight to PG 1634+706.
This system gives rise to a partial Lyman limit break and absorption in MgII,
SiII, CII, SiIII, SiIV, CIV, and OVI. The lower ionization transitions arise in
two kinematic subsystems with a separation of ~150 km/s. Each subsystem is
resolved into several narrow components, having Doppler widths of 3-10 kms. For
both subsystems, the OVI absorption arises in a separate higher ionization
phase, in regions dominated by bulk motions in the range of 30-40 km/s. The two
OVI absorption profiles are kinematically offset by ~50 km/s with respect to
each of the two lower ionization subsystem. In the stronger subsystem, the
SiIII absorption is strong with a distinctive, smooth profile shape and may
partially arise in shock heated gas. Moreover, the kinematic substructure of
SiIV traces that of the lower ionization MgII, but may be offset by ~3 km/s.
Based upon photoionization models, constrained by the partial Lyman limit
break, we infer a low metallicity of ~0.03 solar for the low ionization gas in
both subsystems. The broader OVI phases have a somewhat higher metallicity, and
they are consistent with photoionization; the profiles are not broad enough to
imply production of OVI through collisional ionization. Various models,
including outer disks, dwarf galaxies, and superwinds, are discussed to account
for the phase structure, metallicity, and kinematics of this absorption system.
We favor an interpretation in which the two subsystems are produced by
condensed clouds far out in the opposite extremes of a multi-layer dwarf galaxy
superwind
Tunneling in Fractional Quantum Mechanics
We study the tunneling through delta and double delta potentials in
fractional quantum mechanics. After solving the fractional Schr\"odinger
equation for these potentials, we calculate the corresponding reflection and
transmission coefficients. These coefficients have a very interesting
behaviour. In particular, we can have zero energy tunneling when the order of
the Riesz fractional derivative is different from 2. For both potentials, the
zero energy limit of the transmission coefficient is given by , where is the order of the derivative ().Comment: 21 pages, 3 figures. Revised version; accepted for publication in
Journal of Physics A: Mathematical and Theoretica
Adiabatic Approximation for weakly open systems
We generalize the adiabatic approximation to the case of open quantum
systems, in the joint limit of slow change and weak open system disturbances.
We show that the approximation is ``physically reasonable'' as under wide
conditions it leads to a completely positive evolution, if the original master
equation can be written on a time-dependent Lindblad form. We demonstrate the
approximation for a non-Abelian holonomic implementation of the Hadamard gate,
disturbed by a decoherence process. We compare the resulting approximate
evolution with numerical simulations of the exact equation.Comment: New material added, references added and updated, journal reference
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Analytic approach to bifurcation cascades in a class of generalized H\'enon-Heiles potentials
We derive stability traces of bifurcating orbits in H\'enon-Heiles potentials
near their saddlesComment: LaTeX revtex4, 38 pages, 7 PostScript figures, 2 table
The Kinematic Evolution of Strong MgII Absorbers
We consider the evolution of strong (W_r(2796) > 0.3A) MgII absorbers, most
of which are closely related to luminous galaxies. Using 20 high resolution
quasar spectra from the VLT/UVES public archive, we examine 33 strong MgII
absorbers in the redshift range 0.3 < z < 2.5. We compare and supplement this
sample with 23 strong MgII absorbers at 0.4 < z < 1.4 observed previously with
HIRES/Keck. We find that neither equivalent width nor kinematic spread (the
optical depth weighted second moment of velocity) of MgII2796 evolve. However,
the kinematic spread is sensitive to the highest velocity component, and
therefore not as sensitive to additional weak components at intermediate
velocities relative to the profile center. The fraction of absorbing pixels
within the full velocity range of the system does show a trend of decreasing
with decreasing redshift. Most high redshift systems (14/20) exhibit absorption
over the entire system velocity range, which differs from the result for low
redshift systems (18/36) at the 95% level. This leads to a smaller number of
separate subsystems for high redshift systems because weak absorping components
tend to connect the stronger regions of absorption. We hypothesize that low
redshift MgII profiles are more likely to represent well formed galaxies, many
of which have kinematics consistent with a disk/halo structure. High redshift
MgII profiles are more likely to show evidence of complex protogalactic
structures, with multiple accretion or outflow events. Although these results
are derived from measurements of gas kinematics, they are consistent with
hierarchical galaxy formation evidenced by deep galaxy surveys.Comment: Accepted to the Astrophysical Journa
Uniform approximations for pitchfork bifurcation sequences
In non-integrable Hamiltonian systems with mixed phase space and discrete
symmetries, sequences of pitchfork bifurcations of periodic orbits pave the way
from integrability to chaos. In extending the semiclassical trace formula for
the spectral density, we develop a uniform approximation for the combined
contribution of pitchfork bifurcation pairs. For a two-dimensional double-well
potential and the familiar H\'enon-Heiles potential, we obtain very good
agreement with exact quantum-mechanical calculations. We also consider the
integrable limit of the scenario which corresponds to the bifurcation of a
torus from an isolated periodic orbit. For the separable version of the
H\'enon-Heiles system we give an analytical uniform trace formula, which also
yields the correct harmonic-oscillator SU(2) limit at low energies, and obtain
excellent agreement with the slightly coarse-grained quantum-mechanical density
of states.Comment: LaTeX, 31 pp., 18 figs. Version (v3): correction of several misprint
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