4,075 research outputs found
Experimental research on the Stirling engine
Experiments on Stirling engines of the 50 KW class were conducted to clarify the characteristics of the engine and its problems. The problems involve durability of the high temperature heat exchanger which is exposed to high flame temperatures above 1600 C, thermal distortion and high temperature corrosion of the devices near combustion, and of the preheater
Jet physics in heavy-ion collisions
Jets are expected to play a prominent role in the ongoing efforts to
characterize the hot and dense QCD medium created in ultrarelativistic heavy
ion collisions. The success of this program depends crucially on the existence
of a full theoretical account of the dynamical effects of the medium on the
jets that develop within it. By focussing on the discussion of the essential
ingredients underlying such a theoretical formulation, we aim to set the
appropriate context in which current and future developments can be understood.Comment: 36 pages, 5 figures, few minor corrections, references added. Final
version published in IJMP
Jet coherence in QCD media: the antenna radiation spectrum
We study the radiation of a highly energetic partonic antenna in a colored
state traversing a dense QCD medium. Resumming multiple scatterings of all
involved constituents with the medium we derive the general gluon spectrum
which encompasses both longitudinal color coherence between scattering centers
in the medium, responsible for the well known Landau-Pomeranchuk-Migdal (LPM)
effect, and transverse color coherence between partons inside a jet, leading,
in vacuum, to angular ordering of the parton shower. We discuss shortly the
onset of transverse decoherence which is reached in opaque media. In this
regime, the spectrum consists of independent radiation off the antenna
constituents.Comment: 15 pages, 2 figures, paper shortened and partly rewritten, references
added, results unchange
Dynamic property studies of Sterling engines
A description is given of the results of dynamic property tests that were carried out using a trial produced prototype of a 50 KW Sterling engine. The features of the engine are shown graphically. A high thermal efficiency is found in the low rotation region
Stopping in central Pb + Pb collisions at SPS energies and beyond
We investigate stopping and baryon transport in central relativistic Pb + Pb
and Au + Au collisions. At energies reached at the CERN Super Proton
Synchrotron [sqrt(s_NN) = 6.3-17.3 GeV] and at RHIC (62.4 GeV), we determine
the fragmentation-peak positions from the data. The resulting linear growth of
the peak positions with beam rapidity is in agreement with our results from a
QCD-based approach that accounts for gluon saturation. No discontinuities in
the net-proton fragmentation peak positions occur in the expected transition
region from partons to hadrons at 6-10 GeV.Comment: 5 pages, 3 figures, 1 table. Figures updated, table shortened, 1
reference adde
Bridging the Gap between Probabilistic and Deterministic Models: A Simulation Study on a Variational Bayes Predictive Coding Recurrent Neural Network Model
The current paper proposes a novel variational Bayes predictive coding RNN
model, which can learn to generate fluctuated temporal patterns from exemplars.
The model learns to maximize the lower bound of the weighted sum of the
regularization and reconstruction error terms. We examined how this weighting
can affect development of different types of information processing while
learning fluctuated temporal patterns. Simulation results show that strong
weighting of the reconstruction term causes the development of deterministic
chaos for imitating the randomness observed in target sequences, while strong
weighting of the regularization term causes the development of stochastic
dynamics imitating probabilistic processes observed in targets. Moreover,
results indicate that the most generalized learning emerges between these two
extremes. The paper concludes with implications in terms of the underlying
neuronal mechanisms for autism spectrum disorder and for free action.Comment: This paper is accepted the 24th International Conference On Neural
Information Processing (ICONIP 2017). The previous submission to arXiv is
replaced by this version because there was an error in Equation
Learning Timescales in MTRNNs
We test the viability of having learnable timescales in multi-timescales recurrent neural networks
Antiangular Ordering of Gluon Radiation in QCD Media
We investigate angular and energy distributions of medium-induced gluon
emission off a quark-antiquark antenna in the framework of perturbative QCD as
an attempt toward understanding, from first principles, jet evolution inside
the quark-gluon plasma. In-medium color coherence between emitters, neglected
in all previous calculations, leads to a novel mechanism of soft-gluon
radiation. The structure of the corresponding spectrum, in contrast with known
medium-induced radiation, retains some properties of the vacuum case; in
particular, it exhibits a soft divergency. However, as opposed to the vacuum,
the collinear singularity is regulated by the pair opening angle, leading to a
strict angular separation between vacuum and medium-induced radiation, denoted
as antiangular ordering. We comment on the possible consequences of this new
contribution for jet observables in heavy-ion collisions.Comment: 4 pages, 2 figures; v2. a number of minor improvements, figures
updated, accepted for publication in PR
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