411 research outputs found
The origin of planetary impactors in the inner solar system
New insights into the history of the inner solar system are derived from the
impact cratering record of the Moon, Mars, Venus and Mercury, and from the size
distributions of asteroid populations. Old craters from a unique period of
heavy bombardment that ended 3.8 billion years ago were made by asteroids
that were dynamically ejected from the main asteroid belt, possibly due to the
orbital migration of the giant planets. The impactors of the past 3.8
billion years have a size distribution quite different from the main belt
asteroids, but very similar to the population of near-Earth asteroids.Comment: 12 pages (including 4 figures
The Effect of Slot-Code Optimization on Travel Times in Common Unit-Load Warehouses
The main aim of this paper is to estimate material handling times reductions in one-block unit-load warehouse organised with an optimal slot-code allocation, rather than with a uniform pick/store locations distribution, while comparing single and dual-command cycles from a travel distance perspective; results are calculated through multiple what-if analysis based on random scenarios simulations assuming variable input/output positions and warehouse shapes. Simulations helped in the effective quantification of travel times reductions, gaining a result of extreme importance for those manufacturing, distribution and retailing companies which aim at both designing their warehouse and determining the right type and number of transportation resources. Because of currently used warehouse management systems (WMS), companies do not reckon so needful of existing literature relying on uniform pick/store distribution: this paper seems the first to address a precise estimation of material handling times when fast-movers items are more or less effectively placed nearby warehouses entranc
Storage Location Assignment Problem: implementation in a warehouse design optimization tool
This paper focuses on possible improvements of common practices of warehouse storage management taking cue from Operations Research SLAP (Storage Location Assignment Problem), thus aiming to reach an efficient and organized allocation of products to the warehouse slots. The implementation of a SLAP approach in a tool able to model multiple storage policies will be discussed, with the aim both to reduce the overall required warehouse space - to efficiently allocate produced goods - and to minimize the internal material handling times. The overcome of some of the limits of existing warehousing information management systems modules will be shown, sketching the design of a software tool able to return an organized slot-product allocation. The results of the validation of a prototype on an industrial case are presented, showing the efficiency increase of using the proposed approach with dedicated slot storage policy adoption
Storage Location Assignment Problem: implementation in a warehouse design optimization tool
This paper focuses on possible improvements of common practices of warehouse storage management taking cue from Operations Research SLAP (Storage Location Assignment Problem), thus aiming to reach an efficient and organized allocation of products to the warehouse slots. The implementation of a SLAP approach in a tool able to model multiple storage policies will be discussed, with the aim both to reduce the overall required warehouse space - to efficiently allocate produced goods - and to minimize the internal material handling times. The overcome of some of the limits of existing warehousing information management systems modules will be shown, sketching the design of a software tool able to return an organized slot-product allocation. The results of the validation of a prototype on an industrial case are presented, showing the efficiency increase of using the proposed approach with dedicated slot storage policy adoption
Energy-dependent effective interactions for dilute many-body systems
We address the issue of determining an effective two-body interaction for
mean-field calculations of energies of many-body systems. We show that the
effective interaction is proportional to the phase shift, and demonstrate this
result in the quasiclassical approximation when there is a trapping potential
in addition to the short-range interaction between a pair of particles. We
calculate numerically energy levels for the case of an interaction with a
short-range square-well and a harmonic trapping potential and show that the
numerical results agree well with the analytical expression. We derive a
generalized Gross--Pitaevskii equation which includes effective range
corrections and discuss the form of the electron--atom effective interaction to
be used in calculations of Rydberg atoms and molecules.Comment: 6 pages, 2 figure
CO(J = 1-0) Imaging of M51 with CARMA and the Nobeyama 45 m Telescope
We report the CO(J = 1-0) observations of the Whirlpool Galaxy M51 using both the Combined Array for Research in Millimeter Astronomy (CARMA) and the Nobeyama 45 m telescope (NRO45). We describe a procedure for the combination of interferometer and single-dish data. In particular, we discuss (1) the joint imaging and deconvolution of heterogeneous data, (2) the weighting scheme based on the root-mean-square (rms) noise in the maps, (3) the sensitivity and uv coverage requirements, and (4) the flux recovery of a combined map. We generate visibilities from the single-dish map and calculate the noise of each visibility based on the rms noise. Our weighting scheme, though it is applied to discrete visibilities in this paper, should be applicable to grids in uv space, and this scheme may advance in future software development. For a realistic amount of observing time, the sensitivities of the NRO45 and CARMA visibility data sets are best matched by using the single-dish baselines only up to 4-6 kλ (about 1/4-1/3 of the dish diameter). The synthesized beam size is determined to conserve the flux between the synthesized beam and convolution beam. The superior uv coverage provided by the combination of CARMA long baseline data with 15 antennas and NRO45 short spacing data results in the high image fidelity, which is evidenced by the excellent overlap between even the faint CO emission and dust lanes in an optical Hubble Space Telescope image and polycyclicaromatichydrocarbon emission in a Spitzer 8 μm image. The total molecular gas masses of NGC 5194 and 5195 (d = 8.2 Mpc) are 4.9 × 10^9 M_⊙ and 7.8 × 10^7 M_⊙, respectively, assuming the CO-to-H_2 conversion factor of X _(CO) = 1.8 × 10^(20) cm-2(K km s^(–1))^(–1). The presented images are an indication of the millimeter-wave images that will become standard in the next decade with CARMA and NRO45, and the Atacama Large Millimeter/Submillimeter Array
Compound basis arising from the basic -module
A new basis for the polynomial ring of infinitely many variables is
constructed which consists of products of Schur functions and Q-functions. The
transition matrix from the natural Schur function basis is investigated.Comment: 12 page
Observing Supernova Neutrino Light Curves with Super-Kamiokande. III. Extraction of Mass and Radius of Neutron Stars from Synthetic Data
Neutrinos are guaranteed to be observable from the next Galactic supernova (SN). Optical light and gravitational waves are also observable, but may be difficult to observe if the location of the SN in the Galaxy or the details of the explosion are unsuitable. The key to observing the next SN is to first use neutrinos to understand various physical quantities and then link them to other signals. In this paper, we present Monte Carlo sampling calculations of neutrino events from Galactic SN explosions observed with Super-Kamiokande. The analytical solution of neutrino emission, which represents the long-term evolution of the neutrino light curve from SNe, is used as a theoretical template. It gives the event rate and event spectrum through inverse beta decay interactions with explicit model parameter dependence. Parameter estimation is performed on these simulated sample data by fitting least squares using the analytical solution. The results show that the mass, radius, and total energy of a remnant neutron star produced by an SN can be determined with an accuracy of ∼ 0.1 M⊙, ∼1 km, and ∼ 10⁵¹ erg, respectively, for a Galactic SN at 8 kpc
Central concentration of warm and dense molecular gas in a strongly lensed submillimeter galaxy at z=6
We report the detection of the CO(12-11) line emission toward G09-83808 (or
H-ATLAS J090045.4+004125), a strongly-lensed submillimeter galaxy at , with Atacama Large Millimeter/submillimeter Array observations.
Combining previously detected [O III], [N
II], and dust continuum at 0.6mm and 1.5mm, we
investigate the physical properties of the multi-phase interstellar medium in
G09-83808. A source-plane reconstruction reveals that the region of the
CO(12-11) emission is compact () and roughly coincides with that of
the dust continuum. Non-local thermodynamic equilibrium radiative transfer
modeling of CO spectral-line energy distribution reveals that most of the
CO(12-11) emission comes from a warm (kinetic temperature of
K) and dense
() gas, indicating that the
warm and dense molecular gas is concentrated in the central 0.5-kpc region. The
luminosity ratio in G09-83808 is estimated to be . The high ratio is consistent with those in
local active galactic nuclei (AGNs) and quasars, the fact of which
implies that G09-83808 would be a good target to explore dust-obscured AGNs in
the epoch of reionization. In the reconstructed [O III]
and [N II] cubes, we also find that a monotonic velocity
gradient is extending over the central starburst region by a factor of two and
that star-forming sub-components exist. High-resolution observations of bright
[C II] line emissions will enable us to characterize the
kinematics of a possible rotating disk and the nature of the sub-components.Comment: 13 pages, 11 figures, accepted for publication in PAS
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