1,047 research outputs found
Optimization of vehicle-trailer connection systems
The three main requirements of a vehicle-trailer connection system are: en route
stability, over- or under-steering restraint, minimum off-tracking along curved path. Linking
the two units by four-bar trapeziums, wider stability margins may be attained in comparison
with the conventional pintle-hitch for both instability types, divergent or oscillating. The
stability maps are traced applying the Hurwitz method or the direct analysis of the
characteristic equation at the instability threshold. Several types of four-bar linkages may be
quickly tested, with the drawbars converging towards the trailer or the towing unit. The latter
configuration appears preferable in terms of self-stability and may yield high critical speeds by
optimising the geometrical and physical properties. Nevertheless, the system stability may be
improved in general by additional vibration dampers in parallel with the connection linkage.
Moreover, the four-bar connection may produce significant corrections of the under-steering or
over-steering behaviour of the vehicle-train after a steering command from the driver. The offtracking
along the curved paths may be also optimized or kept inside prefixed margins of
acceptableness. Activating electronic stability systems if necessary, fair results are obtainable
for both the steering conduct and the off-tracking
The Characterization of Complement Fixing Circulating Anti-Body by the Jird (Meriones Unguiculatus) in Response to Infection with Brugia Pahangi over an Extended Period of Time
Male outbred jirds (Merione unguiculatus) were inoculated with doses of 100 or 200 infective Brugia pahangi larvae (13’s), and tested for complement fixing circulating antibody. Following innoculation, all test animals became positive for microfilaria in peripheral blood. Seventeen of 20 test animals developed patent, sustained infections within, or shortly after 60 days. The longest prepotent period was measured at 118 days. Readings of microfilarial densities were taken after the first month, through 12 months, with the final microfilarial reading between 12 and 21 months. Microfilarial densities vacillated through the course of infection.
At the time of necropsy, adult worms were recovered from the testes, heart and pulmonary regions, pelt and carcass and viscera. Recovered adults were sexed and counted for their particular region of residence. The majority of the recovered adults were found in either the testicular region or the pulmonary region with small percentages in other areas. Total worm recovery was between 25% and 30% of the 13 dosage innoculated.
Complement fixation reagent concentrations; Rabbit Hemolysin, Guinea Pig Complement, and B. pahangi antigen were titrated and standardized (HEW Technical Report, 1965). Complement fixation tests were performed with test sera from infected animals divided into 2 groups (A & B), Group A animals had consistently low microfilarial densities throughout the course of infection
(\u3c500) with Group B maintaining high densities throughout (\u3e500). The lowest positive titer was determined at 1:4 with the highest titer observed at 1:256. Animals of Group A were demonstrated at having significantly greater mean antibody titers during the third, sixth and post twelve month periods with relation to Group B. The complement fixation titers showed a correlation between microfilarial densities and mean antibody titers, between the two test groups, at significant time periods
Remnants of Initial Anisotropic High Energy Density Domains in Nucleus-Nucleus Collisions
Anisotropic high energy density domains may be formed at early stages of
ultrarelativistic heavy ion collisions, e.g. due to phase transition dynamics
or non-equilibrium phenomena like (mini-)jets. Here we investigate hadronic
observables resulting from an initially created anisotropic high energy density
domain. Based on our studies using a transport model we find that the initial
anisotropies are reflected in the freeze-out multiplicity distribution of both
pions and kaons due to secondary hadronic rescattering. The anisotropy appears
to be stronger for particles at high transverse momenta. The overall kaon
multiplicity increases with large fluctuations of local energy densities, while
no change has been found in the pion multiplicity.Comment: Submitted to PR
Evidence of early multi-strange hadron freeze-out in high energy nuclear collisions
Recently reported transverse momentum distributions of strange hadrons
produced in Pb(158AGeV) on Pb collisions and corresponding results from the
relativistic quantum molecular dynamics (RQMD) approach are examined. We argue
that the experimental observations favor a scenario in which multi-strange
hadrons are formed and decouple from the system rather early at large energy
densities (around 1 GeV/fm). The systematics of the strange and non-strange
particle spectra indicate that the observed transverse flow develops mainly in
the late hadronic stages of these reactions.Comment: 4 pages, 4 figure
Thermal analysis of hadron multiplicities from relativistic quantum molecular dynamics
Some questions arising in the application of the thermal model to hadron
production in heavy ion collisions are studied. We do so by applying the
thermal model of hadron production to particle yields calculated by the
microscopic transport model RQMD(v2.3). We study the bias of incomplete
information about the final hadronic state on the extraction of thermal
parameters.It is found that the subset of particles measured typically in the
experiments looks more thermal than the complete set of stable particles. The
hadrons which show the largest deviations from thermal behaviour in RQMD(v2.3)
are the multistrange baryons and antibaryons. We also looked at the influence
of rapidity cuts on the extraction of thermal parameters and found that they
lead to different thermal parameters and larger disagreement between the RQMD
yields and the thermal model.Comment: 12 pages, 2 figures, uses REVTEX, only misprint and stylistic
corrections, to appear in Physical Review
On the Equation of State of Nuclear Matter in 158A GeV Pb+Pb Collisions
Within a hydrodynamical approach we investigate the sensitivity of single
inclusive momentum spectra of hadrons in 158A GeV Pb+Pb collisions to three
different equations of state of nuclear matter. Two of the equations of state
are based on lattice QCD results and include a phase transition to a
quark-gluon plasma. The third equation of state has been extracted from the
microscopic transport code RQMD under the assumption of complete local
thermalization. All three equations of state provide reasonable fits to data
taken by the NA44 and NA49 Collaborations. The initial conditions before the
evolution of the fireballs and the space-time evolution pictures differ
dramatically for the three equations of state when the same freeze-out
temperature is used in all calculations. However, the softest of the equations
of state results in transverse mass spectra that are too steep in the central
rapidity region. We conclude that the transverse particle momenta are
determined by the effective softness of the equation of state during the
fireball expansion.Comment: 4 pages, including 4 figures and 2 tables. For a PostScript file of
the manuscript, you can also goto http://t2.lanl.gov/schlei/eprint.htm
Systematic Study of the Kaon to Pion Multiplicity Ratios in Heavy-Ion Collisions
We present a systematic study of the kaon to pion multiplicity ratios (K+/pi+
and K-/pi-) in heavy-ion collisions from AGS to RHIC energy using the
Relativistic Quantum Molecular Dynamics (RQMD) model. The model satisfactorily
describes the available experimental data on K+/pi+ and K-/pi-. Within the
model, we find that the strong increase of the ratios with the number of
participants is mainly due to hadronic rescattering of produced mesons with
ingoing baryons and their resonances. The enhancement of K/pi in heavy-ion
collisions with respect to elementary p+p interactions is larger at AGS energy
than SPS energy, and decreases smoothly with bombarding energy. The total
multiplicity ratios at RHIC energy are predicted by RQMD to be K+/pi+ = 0.19
and K-/pi- = 0.15.Comment: 10 pages, 8 figures, RevTeX style. A section is added to discuss
effects of rope formatio
A stopped Delta-Matter Source in Heavy Ion Collisions at 10 GeV/n
We predict the formation of highly dense baryon-rich resonance matter in
Au+Au collisions at AGS energies. The final pion yields show observable signs
for resonance matter. The Delta(1232) resonance is predicted to be the dominant
source for pions of small transverse momenta. Rescattering effects --
consecutive excitation and deexcitation of Deltas -- lead to a long apparent
lifetime (> 10 fm/c) and rather large volumina (several 100 fm^3) of the
Delta-matter state. Heavier baryon resonances prove to be crucial for reaction
dynamics and particle production at AGS.Comment: 17 pages, 5 postscript figures, uses psfig.sty and revtex.st
A Monte Carlo approach to study neutron and fragment emission in heavy-ion reactions
Quantum Molecular Dynamics models (QMD) are Monte Carlo approaches targeted
at the description of nucleon-ion and ion-ion collisions. We have developed a
QMD code, which has been used for the simulation of the fast stage of ion-ion
collisions, considering a wide range of system masses and system mass
asymmetries. The slow stage of the collisions has been described by statistical
methods. The combination of both stages leads to final distributions of
particles and fragments, which have been compared to experimental data
available in literature. A few results of these comparisons, concerning neutron
double-differential production cross-sections for C, Ne and Ar ions impinging
on C, Cu and Pb targets at 290 - 400 MeV/A bombarding energies and fragment
isotopic distributions from Xe + Al at 790 MeV/A, are shown in this paper.Comment: 12 pages, 3 figures, submitted for publication in Adv. Space Re
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