5,271 research outputs found
Excitation Functions of Stopping Power and Flow in Relativistic Heavy-Ion Collisions
Using a relativistic transport (ART) model, we study the stopping power, the
formation of superdense hadronic matter as well as the strength of transverse
and radial flow in central Au+Au collisions at beam momentum from 2 to 12 GeV/c
per nucleon. We find that complete stopping is achieved in the whole beam
momentum range. In particular, the proton rapidity distribution scaled by the
beam rapidity is independent of the beam momentum, and this is in agreement
with the experimental findings. Also, a large volume of superdense hadronic
matter with a local energy density exceeding that expected for the transition
of a hadronic matter to the quark-gluon plasma is formed in collisions at beam
momenta greater than 8 GeV/c per nucleon. Furthermore, it is found that the
transverse flow in these collisions is sensitive to the nuclear equation of
state and decreases with increasing beam momentum. On the other hand, the
radial flow is insensitive to the equation of state, and its strength increases
with beam momentum.Comment: Talk given at NN97, Gatlinburg, Tennessee June 2-6,1997. To appear in
the proc. in Nucl. Phys.
Can Performance of Indigenous Factors Influence Growth and Globalisation?"
This paper employs a total of thirty four openness factors and indigenous factors to construct two indicators for 62 world economies for the period 1998-2002. While most globalization studies concentrated on openness factors, regression estimates and simulation studies show that sound performance in indigenous factors are crucial to an economyâs growth and globalization. Empirical evidence shows that an optimal performance in indigenous factors can be identified, and that successful globalized economies are equipped with strong performance in their indigenous factors.Globalization; indigenous factors; openess; world economies
A framework for integrating syntax, semantics and pragmatics for computer-aided professional practice: With application of costing in construction industry
Producing a bill of quantity is a knowledge-based, dynamic and collaborative process, and evolves with variances and current evidence. However, within the context of information system practice in BIM, knowledge of cost estimation has not been represented, nor has it been integrated into the processes based on BIM. This paper intends to establish an innovative means of taking data from the BIM linked to a project, and using it to create the necessary items for a bill of quantity that will enable cost estimation to be undertaken for the project. Our framework is founded upon the belief that three components are necessary to gain a full awareness of the domain which is being computerised; the information type which is to be assessed for compatibility (syntax), the definition for the pricing domain (semantics), and the precise implementation environment for the standards being taken into account (pragmatics). In order to achieve this, a prototype is created that allows a cost item for the bill of quantity to be spontaneously generated, by means of the semantic web ontology and a forward chain algorithm. Within this paper, âcost itemsâ signify the elements included in a bill of quantity, including details of their description, quantity and price. As a means of authenticating the process being developed, the authors of this work effectively implemented it in the production of cost items. In addition, the items created were contrasted with those produced by specialists. For this reason, this innovative framework introduces the possibility of a new means of applying semantic web ontology and forward chain algorithm to construction professional practice resulting in automatic cost estimation. These key outcomes demonstrate that, decoupling the professional practice into three key components of syntax, semantics and pragmatics can provide tangible benefits to domain use
A New Exponential Gravity
We propose a new exponential f(R) gravity model with f(R)=(R-\lambda
c)e^{\lambda(c/R)^n} and n>3, \lambda\geq 1, c>0 to explain late-time
acceleration of the universe. At the high curvature region, the model behaves
like the \LambdaCDM model. In the asymptotic future, it reaches a stable
de-Sitter spacetime. It is a cosmologically viable model and can evade the
local gravity constraints easily. This model share many features with other
f(R) dark energy models like Hu-Sawicki model and Exponential gravity model. In
it the dark energy equation of state is of an oscillating form and can cross
phantom divide line \omega_{de}=-1. In particular, in the parameter range 3<
n\leq 4, \lambda \sim 1, the model is most distinguishable from other models.
For instance, when n=4, \lambda=1, the dark energy equation of state will cross
-1 in the earlier future and has a stronger oscillating form than the other
models, the dark energy density in asymptotical future is smaller than the one
in the high curvature region. This new model can evade the local gravity tests
easily when n>3 and \lambda>1.Comment: 12 pages, 8 figure
Uranium on uranium collisions at relativistic energies
Deformation and orientation effects on compression, elliptic flow and
particle production in uranium on uranium collisions (UU) at relativistic
energies are studied within the transport model ART. The density compression in
tip-tip UU collisions is found to be about 30% higher and lasts approximately
50% longer than in body-body or spherical UU reactions. The body-body UU
collisions have the unique feature that the nucleon elliptic flow is the
highest in the most central collisions and remain a constant throughout the
reaction. We point out that the tip-tip UU collisions are more probable to
create the QGP at AGS and SPS energies while the body-body UU collisions are
more useful for studying properties of the QGP at higher energies.Comment: 8 pages + 4 figure
Polydimethylsiloxane (PDMS)-based microfluidic channel with integrated commercial pressure sensors
The precise characterisation of boiling in microchannels is essential for the optimisation of applications requiring two phase cooling. In this paper polydimethylsiloxane (PDMS) is employed to make microchannels for characterising microboiling. In particular the material properties of PDMS facilitate rapid prototyping and its optical transparency provides the capability to directly view any fluid flow. The production of microchannels is complicated by the need to integrate custom made sensors. This paper presents a PDMS microfluidic device with integrated commercial pressure sensors, which have been used to perform a detailed characterisation of microboiling phenomena. The proposed approach of integrating commercial pressure sensors into the channel also has potential applications in a range of other microsystems
Thermal Hall conductivity of marginal Fermi liquids subject to out-of plane impurities in high- cuprates
The effect of out-of-plane impurities on the thermal Hall conductivity
of in-plane marginal-Fermi-liquid (MFL) quasiparticles in
high- cuprates is examined by following the work on electrical Hall
conductivity by Varma and Abraham [Phys. Rev. Lett. 86, 4652
(2001)]. It is shown that the effective Lorentz force exerted by these
impurities is a weak function of energies of the MFL quasiparticles, resulting
in nearly the same temperature dependence of and ,
indicative of obedience of the Wiedemann-Franz law. The inconsistency of the
theoretical result with the experimental one is speculated to be the
consequence of the different amounts of out-of-plane impurities in the two
YBaCuO samples used for the and measurements.Comment: 5 pages, 2 eps figures; final versio
Antikaon Production and Medium Effects in Heavy Ion Collisions at AGS
Antikaon production from heavy ion collisions at energies available from the
Alternating Gradient Synchrotron (AGS) at the Brookhaven National Laboratory is
studied in a relativistic transport (ART) model. We include contributions from
the baryon-baryon, meson-baryon, and meson-meson interactions. The final-state
interaction of antikaons via both absorption and elastic scattering by nucleons
and pions are also considered. To compare with presently available or future
experimental data, we have calculated the antikaon rapidity and transverse
momentum distributions as well as its collective flow. Medium effects on these
observables due to mean field potentials have also been investigated. It is
found that the ratio of antikaon transverse momentum spectrum to that of kaon
and their transverse flow are most sensitive to the in-medium properties of
kaons and antikaons.Comment: 19 pages, 13 figure
Enhancement of low- kaons in AGS heavy-ion collisions
In the relativistic transport model, we show that the recently observed
enhancement of low- kaons ( and ) in Si+Pb collisions at AGS can
be explained if a density isomer is introduced in the nuclear
equation-of-state.Comment: 12 pages, RevTex, 6 figs on request to [email protected]
Response to comments on âA numerical method to determine interdiffusion coefficients of Cu6Sn5 and Cu3Sn intermetallic compoundsâ
Comments have recently been made by Yuan et al. [1] to deny one statement in our paper [2], Eq. (21) in Wagner's paper [3] can be used to accurately calculate the integrated interdiffusion coefficient for an incremental diffusion couple only under the assumption of constant Molar volume for all phases. We respond here to explain how they misunderstood our mathematical deduction, made a mistake in deriving a couple of equations, falsely cited our work and employed unjustifiable assumption. As a result, we believe that their comments are invalid to deny our statement
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