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51.
Mathieu Génois Pascal Hersen Sylvain Courrech du Pont Guillaume Grégoire 《The European Physical Journal B - Condensed Matter and Complex Systems》2013,86(11):1-13
In order to test parameters of the peculiar dynamics occurring in barchan fields, and compute statistical analysis over large numbers of dunes, we build and study an agent-based model, which includes the well-known physics of an isolated barchan, and observations of interactions between dunes. We showed in a previous study that such a model, where barchans interact through short-range sand recapture and collisions, reproduces the peculiar behaviours of real fields, namely its spatial structuring along the wind direction, and the size selection by the local density. In this paper we focus on the mechanisms that drives these features. In particular, we show that eolian remote sand transfer between dunes ensures that a dense field structures itself into a very heterogeneous pattern, which alternates dense and diluted stripes in the wind direction. In these very dense clusters of dunes, the accumulation of collisions leads to the local emergence of a new size for the dunes. 相似文献
52.
Ibrahim Ari Vural Aksakalli Volkan Aydogˇdu Serdar Kum 《European Journal of Operational Research》2013
We consider the optimal ship navigation problem wherein the goal is to find the shortest path between two given coordinates in the presence of obstacles subject to safety distance and turn-radius constraints. These obstacles can be debris, rock formations, small islands, ice blocks, other ships, or even an entire coastline. We present a graph-theoretic solution on an appropriately-weighted directed graph representation of the navigation area obtained via 8-adjacency integer lattice discretization and utilization of the A∗ algorithm. We explicitly account for the following three conditions as part of the turn-radius constraints: (1) the ship’s left and right turn radii are different, (2) ship’s speed reduces while turning, and (3) the ship needs to navigate a certain minimum number of lattice edges along a straight line before making any turns. The last constraint ensures that the navigation area can be discretized at any desired resolution. Once the optimal (discrete) path is determined, we smoothen it to emulate the actual navigation of the ship. We illustrate our methodology on an ice navigation example involving a 100,000 DWT merchant ship and present a proof-of-concept by simulating the ship’s path in a full-mission ship handling simulator. 相似文献
53.
The main purpose of this paper is to set a method of finding eigenvalues of split quaternion matrices. In particular, we will give an extension of Gershgorin theorem, which is one of the fundamental theorems of complex matrix theory, for split quaternion matrices. 相似文献
54.
In this paper, we present some important properties of complex split quaternions and their matrices. We also prove that any complex split quaternion has a 4 × 4 complex matrix representation. On the other hand, we give answers to the following two basic questions “If AB = I, is it true that BA = I for complex split quaternion matrices?” and “How can the inverse of a complex split quaternion matrix be found?”. Finally, we give an explicit formula for the inverse of a complex split quaternion matrix by using complex matrices. 相似文献
55.
Comprehensive fission measurements, including mass-angle distributions, for the reaction of 32S with the prolate deformed nucleus 232Th at near-barrier energies show two distinct components in both mass and angle; surprisingly, both have characteristics of quasifission. Their relative probabilities vary rapidly with the ratio of the beam energy to the capture barrier, suggesting a relationship with deformation aligned (sub-barrier), or antialigned (above-barrier), configurations at contact. 相似文献
56.
57.
The electrostriction-induced acoustic effect introduces a time-dependent index evolution for the following optical pulses and results in an additional temporal shift of solitons. The acoustic effect is incorporated into the nonlinear Schr?dinger equation as a perturbative term. We investigate the evolution of timing jitter, taking into account both the Gordon-Haus and the acoustic effect contributions for a 10-Gbit/s sliding-frequency in-line-filter soliton system. 相似文献
58.
Ivano Tavernelli Dr. Marie‐Pierre Gaigeot Prof. Rodolphe Vuilleumier Dr. Carlos Stia Dr. Marie‐Anne Hervé du Penhoat Dr. Marie‐Françoise Politis Dr. 《Chemphyschem》2008,9(14):2099-2103
The early stages of the Coulomb explosion of a doubly ionized water molecule immersed in liquid water are investigated with time‐dependent density functional theory molecular dynamics (TD–DFT MD) simulations. Our aim is to verify that the double ionization of one target water molecule leads to the formation of atomic oxygen as a direct consequence of the Coulomb explosion of the molecule. To that end, we used TD–DFT MD simulations in which effective molecular orbitals are propagated in time. These molecular orbitals are constructed as a unitary transformation of maximally localized Wannier orbitals, and the ionization process was obtained by removing two electrons from the molecular orbitals with symmetry 1B1, 3A1, 1B2 and 2A1 in turn. We show that the doubly charged H2O2+ molecule explodes into its three atomic fragments in less than 4 fs, which leads to the formation of one isolated oxygen atom whatever the ionized molecular orbital. This process is followed by the ultrafast transfer of an electron to the ionized molecule in the first femtosecond. A faster dissociation pattern can be observed when the electrons are removed from the molecular orbitals of the innermost shell. A Bader analysis of the charges carried by the molecules during the dissociation trajectories is also reported. 相似文献
59.
G. Erdoǧdu 《Journal of Analytical Chemistry》2008,63(8):762-767
The electrochemical characteristics of azinphos-ethyl (APE) have been determined by means of electrochemical techniques such
as cyclic voltammetry (CV) and adsorptive stripping voltammetry (ASV) at a hanging mercury drop electrode (HMDE) over a wide
range of pH from 2.0 to 8.0. The cyclic voltammograms demonstrate the adsorption of this compound at the mercury electrode.
A systematic study of the various operational parameters that affect the stripping response was carried out by differential
pulse voltammetry (DPV). With a preconcentration potential of −0.6 V and a 60 s preconcentration time, the limit of detection
was 5.42 × 10−9 M, and the relative standard deviation (n = 5) was 2.7 % at concentration level of 6.45 × 10−7 M APE. The degree of interference from diverse ions and some other pesticides on the differential pulse stripping signal
for APE was evaluated. Finally, the method was applied to the determination of APM in spiked soil, tap water, and treated
wastewater.
The text was submitted by the author in English. 相似文献
60.
Thillaye du Boullay O Bonduelle C Martin-Vaca B Bourissou D 《Chemical communications (Cambridge, England)》2008,(15):1786-1788
Well-controlled poly(alpha-hydroxyacids) featuring pendant carboxylic acid groups were prepared under mild conditions via DMAP-catalyzed ROP of the O-carboxyanhydrides derived from glutamic and lactic acids. 相似文献