30,528 research outputs found
Modulation and coding for quantized channels
We investigate reliable communication over quantized channels from an information theoretical point of view. People seldom consider the effect of quantization in conventional coded modulation systems since Analog-to-Digital (AD) converters used in these systems always have high resolution, e.g. 2/3 source bits are often quantized into 10/12 bits. However, AD converters with a high resolution are power consuming. In this paper, we present a scheme to design an optimum quantizer with low resolution which can be used to communicate over the quantized channel. Moreover, we show that reliable transmission over the Additive White Gaussian Noise (AWGN) channel at a rate of R bit/use is possible with R + 1 or R + 2 quantized bits.\u
Study on SPH Viscosity Term Formulations
For viscosity-dominated flows, the viscous effect plays a much more important role. Since the viscosity term in SPH-governing (Smoothed Particle Hydrodynamics) equations involves the discretization of a second-order derivative, its treatment could be much more challenging than that of a first-order derivative, such as the pressure gradient. The present paper summarizes a series of improved methods for modeling the second-order viscosity force term. By using a benchmark patch test, the numerical accuracy and efficiency of different approaches are evaluated under both uniform and non-uniform particle configurations. Then these viscosity force models are used to compute a documented lid-driven cavity flow and its interaction with a cylinder, from which the most recommended viscosity term formulation has been identified
Density profiles of supernova matter and determination of neutrino parameters
The flavor conversion of supernova neutrinos can lead to observable
signatures related to the unknown neutrino parameters. As one of the
determinants in dictating the efficiency of resonant flavor conversion, the
local density profile near the MSW resonance in a supernova environment is,
however, not so well understood. In this analysis, variable power-law functions
are adopted to represent the independent local density profiles near the
locations of resonance. It is shown that the uncertain matter density profile
in a supernova, the possible neutrino mass hierarchies, and the undetermined
1-3 mixing angle would result in six distinct scenarios in terms of the
survival probabilities of and . The feasibility of
probing the undetermined neutrino mass hierarchy and the 1-3 mixing angle with
the supernova neutrinos is then examined using several proposed experimental
observables. Given the incomplete knowledge of the supernova matter profile,
the analysis is further expanded to incorporate the Earth matter effect. The
possible impact due to the choice of models, which differ in the average energy
and in the luminosity of neutrinos, is also addressed in the analysis.Comment: 27 pages, 10 figures. text and figures revised, references added, to
appear in Phys. Rev.
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Laser-assisted photothermal imprinting of nanocomposite
We report on a laser-assisted photothermal imprinting method for directly patterning carbon
nanofiber-reinforced polyethylene nanocomposite. A single laser pulse from a solid state
Nd:YAG laser (10 ns pulse, 532 nm and 355 nm wavelengths) is used to melt/soften a thin skin
layer of the polymer nanocomposite. Meanwhile, a fused quartz mold with micro-sized surface
relief structures is pressed against the surface of the composite. Successful pattern transfer is
realized upon releasing the quartz mold. Although polyethylene is transparent to the laser beam,
the carbon nanofibers in the high density polyethylene (HDPE) matrix absorb the laser energy
and convert it into heat. Numerical heat conduction simulation shows the HDPE matrix is
partially melted or softened, allowing for easier imprinting of the relief pattern of the quartz
mold.Mechanical Engineerin
Electroweak and QCD corrections to top-pair hadroproduction in association with heavy bosons
We compute the contribution of order to the cross
section of a top-antitop pair in association with at least one heavy Standard
Model boson -- , , and Higgs -- by including all effects of QCD, QED,
and weak origin and by working in the automated MadGraph5_aMC@NLO framework.
This next-to-leading order contribution is then combined with that of order
, and with the two dominant lowest-order ones,
and , to obtain phenomenological results
relevant to a 8, 13, and 100~TeV collider.Comment: 27 pages, 8 figure
Gisin's Theorem for Arbitrary Dimensional Multipartite States
We present a set of Bell inequalities which are sufficient and necessary for
separability of general pure multipartite quantum states in arbitrary
dimensions. The relations between Bell inequalities and distillability are also
studied. We show that any quantum states that violate one of these Bell
inequalities are distillable.Comment: 5 page
Weak corrections to Higgs hadroproduction in association with a top-quark pair
We present the calculation of the next-to-leading contribution of order
to the production of a Standard Model Higgs boson in
association with a top-quark pair at hadron colliders. All effects of weak and
QCD origin are included, whereas those of QED origin are ignored. We work in
the MadGraph5_aMC@NLO framework, and discuss sample phenomenological
applications at a 8, 13, and 100 TeV collider, including the effects of
the dominant next-to-leading QCD corrections of order .Comment: 29 pages, 38 figure
Microwave Slow-Wave Structure and Phase-Compensation Technique for Microwave Power Divider
In this paper, T-shaped electromagnetic bandgap is loaded on a coupled transmission line itself and its electric performance is studied. Results show that microwave slow-wave effect can be enhanced and therefore, size reduction of a transmission-line-based circuit is possible. However, the transmission-line-based circuits characterize varied phase responses against frequency, which becomes a disadvantage where constant phase response is required. Consequently, a phase-compensation technique is further presented and studied. For demonstration purpose, an 8-way coupled-line power divider with 22.5 degree phase shifts between adjacent output ports, based on the studied slow-wave structure and phase-compensation technique, is developed. Results show both compact circuit architecture and improved phase imbalance are realized, confirming the investigated circuit structures and analyzing methodologies
Multi-Source Multi-View Clustering via Discrepancy Penalty
With the advance of technology, entities can be observed in multiple views.
Multiple views containing different types of features can be used for
clustering. Although multi-view clustering has been successfully applied in
many applications, the previous methods usually assume the complete instance
mapping between different views. In many real-world applications, information
can be gathered from multiple sources, while each source can contain multiple
views, which are more cohesive for learning. The views under the same source
are usually fully mapped, but they can be very heterogeneous. Moreover, the
mappings between different sources are usually incomplete and partially
observed, which makes it more difficult to integrate all the views across
different sources. In this paper, we propose MMC (Multi-source Multi-view
Clustering), which is a framework based on collective spectral clustering with
a discrepancy penalty across sources, to tackle these challenges. MMC has
several advantages compared with other existing methods. First, MMC can deal
with incomplete mapping between sources. Second, it considers the disagreements
between sources while treating views in the same source as a cohesive set.
Third, MMC also tries to infer the instance similarities across sources to
enhance the clustering performance. Extensive experiments conducted on
real-world data demonstrate the effectiveness of the proposed approach
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