101,525 research outputs found
An Improved Differential Evolution Algorithm for Maritime Collision Avoidance Route Planning
High accuracy navigation and surveillance systems are pivotal to ensure efficient ship route planning and marine safety. Based on existing ship navigation and maritime collision prevention rules, an improved approach for collision avoidance route planning using a differential evolution algorithm was developed. Simulation results show that the algorithm is capable of significantly enhancing the optimized route over current methods. It has the potential to be used as a tool to generate optimal vessel routing in the presence of conflicts
Detecting relic gravitational waves in the CMB: A statistical bias
Analyzing the imprint of relic gravitational waves (RGWs) on the cosmic
microwave background (CMB) power spectra provides a way to determine the signal
of RGWs. In this Letter, we discuss a statistical bias, which could exist in
the data analysis and has the tendency to overlook the RGWs. We also explain
why this bias exists, and how to avoid it.Comment: 4 pages, 1 figur
Is the CMB asymmetry due to the kinematic dipole?
Parity violation found in the Cosmic Microwave Background (CMB) radiation is
a crucial clue for the non-standard cosmological model or the possible
contamination of various foreground residuals and/or calibration of the CMB
data sets. In this paper, we study the directional properties of the CMB parity
asymmetry by excluding the modes in the definition of parity parameters.
We find that the preferred directions of the parity parameters coincide with
the CMB kinematic dipole, which implies that the CMB parity asymmetry may be
connected with the possible contamination of the residual dipole component. We
also find that such tendency is not only localized at , but in the
extended multipole ranges up to .Comment: 17 pages, 5 figures, 2 tables, improved version, ApJ accepte
Impact of pairing correlations on the orientation of the nuclear
For the first time, the tilted axis cranking covariant density functional
theory with pairing correlations has been formulated and implemented in a fully
self-consistent and microscopic way to investigate the evolution of the spin
axis and the pairing effects in rotating triaxial nuclei. The measured energy
spectrum and transition probabilities for the Nd-135 yrast band are reproduced
well without any ad hoc renormalization factors when pairing effects are taken
into account. A transition from collective to chiral rotation has been
demonstrated. It is found that pairing correlations introduce additional
admixtures in the single-particle orbitals, and, thus, influence the structure
of tilted axis rotating nuclei by reducing the magnitude of the proton and
neutron angular momenta while merging their direction.Comment: 13 pages, 5 figure
Self-consistent models of triaxial galaxies in MOND gravity
The Bekenstein-Milgrom gravity theory with a modified Poisson equation is
tested here for the existence of triaxial equilibrium solutions. Using the
non-negative least square method, we show that self-consistent triaxial
galaxies exist for baryonic models with a mild density cusp . Self-consistency is achieved for a wide range of central
concentrations, , representing
low-to-high surface brightness galaxies. Our results demonstrate for the first
time that the orbit superposition technique is fruitful for constructing galaxy
models beyond Newtonian gravity, and triaxial cuspy galaxies might exist
without the help of Cold dark Matter.Comment: 19 pages, 1 table, 7 figures, Accepted for publication in Ap
A New Kind of Uniformly Accelerated Reference Frames
A new kind of uniformly accelerated reference frames with a line-element
different from the M{\o}ller and Rindler ones is presented, in which every
observer at consts. has the same constant acceleration. The laws of
mechanics are checked in the new kind of frames. Its thermal property is
studied. The comparison with the M{\o}ller and Rindler uniform accelerated
reference frames is also made.Comment: 10 pages, 2 figures. to appear in Int. J. Mod. Phys.
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A Film Fabrication Process on Transparent Substrate using Mask Projection Micro-Stereolithography
In this study, a Mask Projection Micro-Stereolithography (MP”SLA) process with the
ability to cure a film of various thicknesses on transparent substrates is presented. Incident
radiation, patterned by a dynamic mask, passes through a transparent substrate to cure
photopolymer resin layers that grow progressively from the substrate surface. When compared
to existing Stereolithography techniques, this technique eliminates the necessity of recoating,
reducing process time and improving accuracy. A film of varying thicknesses can be fabricated
on flat or curved transparent substrates. Models of the optical system and resin cure are
developed and reported. An existing MP”SLA process planning method is being extended to
account for radiation transmission through a substrate. The models are verified using
experiments.Mechanical Engineerin
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