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921.
922.
Majid Soolaki Iraj Mahdavi Nezam Mahdavi-Amiri Reza Hassanzadeh Aydin Aghajani 《Applied Mathematical Modelling》2012
The airline industry is under intense competition to simultaneously increase efficiency and satisfaction for passengers and profitability and internal system benefit for itself. The boarding process is one way to achieve these objectives as it tends itself to adaptive changes. In order to increase the flying time of a plane, commercial airlines try to minimize the boarding time, which is one of the most lengthy parts of a plane’s turn time. To reduce boarding time, it is thus necessary to minimize the number of interferences between passengers by controlling the order in which they get onto the plane through a boarding policy. Here, we determine the passenger boarding problem and examine the different kinds of passenger boarding strategies and boarding interferences in a single aisle aircraft. We offer a new integer linear programming approach to reduce the passenger boarding time. A genetic algorithm is used to solve this problem. Numerical results show effectiveness of the proposed algorithm. 相似文献
923.
This paper aims to develop a mixed load algorithm for the school bus routing problem (SBRP) and measure its effects on the number of required vehicles. SBRP seeks to find optimal routes for a fleet of vehicles, where each vehicle transports students from their homes and to their schools while satisfying various constraints. When mixed load is allowed, students of different schools can get on the same bus at the same time. Although many of real world SBRP allow mixed load, only a few studies have considered these cases. In this paper, we present a new mixed load improvement algorithm and compare it with the only existing algorithm from the literature. Benchmark problems are proposed to compare the performances of algorithms and to stimulate other researchers’ further study. The proposed algorithm outperforms the existing algorithm on the benchmark problem instances. It has also been successfully applied to some of real-world SBRP and could reduce the required number of vehicles compared with the current practice. 相似文献
924.
Despite a state-of-the-art filter for removing Gaussian noise, non-local means filter (NLM), like its local counterpart (the mean filter), is no longer so effective in removing salt-pepper noise which is common in real world as well. By contrast, adaptive median filter (AMF) is concise and can remove this type of noise effectively. Inspired by the AMF filtering strategies, in this paper, we modify NLM to a novel non-local universal filter (UNLM) which can remove not only either of Gaussian noise and salt-pepper noise but also their mixture. Experiments on artificial and benchmark images validate its feasibility and effectiveness. 相似文献
925.
A new mixed Petrov–Galerkin formulation employing the MINI element with a non-confirming bubble function for an incompressible media governed by the Stokes equations, which is equivalent to the stabilized finite element by P 1-P 1 approximation, is proposed. The new formulation possesses better stability properties than the conventional Bubnov–Galerkin formulation employing the MINI element. In this aspect, the stabilizing effect of this formulation is evaluated by a stabilizing parameter determined by both shapes of the trial and the weighting bubble functions. 相似文献
926.
Saburo Matunaga 《Acta Mechanica Sinica》2012,28(2):551-558
This paper focuses on the attitude control problem of small agile satellites using single-gimbal control moment gyros(CMG) and magnetic torquers(MTQ).CMGs are regarded as effective torque generators for agile satellites because of their torque amplification capability.However,they are vulnerable to failure due to their complex inner mechanism.In this paper,different failure cases of CMGs are analyzed.A flexible failure-tolerant control strategy is developed by automatically redistributing the required control torque among the operating CMGs and MTQs,with a variable limiter to accommodate the actuator dynamics changes introduced by CMG failures.The performances of maneuvers about different directions under different failure cases are also discussed and examined.Numerical simulations demonstrate that the proposed strategy maintains certain agility in the cases of one or two CMGs failing.Moreover,a survival strategy with only one CMG left is also verified.Both sun-pointing stabilization and earth-pointing stabilization can be achieved in this case,which fulfill some basic mission requirements. 相似文献
927.
Thin films of polymer electrolytes comprising of PVA and KOH (A) with and without the addition of zinc salts, viz., zinc acetate (B) and zinc triflate (C) as mixed cations were prepared via. solution casting method. The thermal stability and ionic conductivity of PVA–KOH solid
polymer electrolyte (A) were improved by the partial substitution of KOH with zinc salts. Among the two salts, zinc triflate was found to improve
both the physical as well as electrochemical properties of the PVA–KOH films more significantly than zinc acetate. An attempt
to optimize the ratio of various components of polymer electrolytes, viz., polymer: KOH: zinc salt was also made, based on
the dimensional stability and ionic conductivity values. Finally, the select category polymer film containing PVA–KOH–zinc
triflate (C) in an optimum ratio of 40:35:25 was deployed in coin cell fabrication and subjected to charge–discharge studies with a view
to demonstrate the possible electrochemical reversibility characteristics. Based on the encouraging results obtained from
the cycling study, C type films [PVA–KOH–zinc triflate] qualify themselves as potential polymer electrolytes for use in rechargeable Zn/AgO polymer
batteries. 相似文献
928.
András Varga Mónika Huszár Zsófia Dobos Éva Kiss Anikó Horváth Miklós Idei 《Electrophoresis》2009,30(11):1923-1928
Lipophilicity and methylene selectivity of mixed pseudo‐stationary phases (PSPs) (containing lithium dodecyl sulphate (LDS) and lithium perfluorooctanesulphonate (LiPFOS) in different molar ratios) applied in MEKC have been investigated. Micellar proportion (tprop,mic, a quantity expressing that how much time is spent by the analyte in the micellar phase related to its whole migration time), CLOGP50 value (showing the value of hydrophobicity of a molecule spending exactly 50% of its migration time in the PSP) and methylene selectivity have been determined for different LDS/LiPFOS mixed phases. Values of the above‐mentioned parameters have been determined for analytes with different chemical structures (alkylbenzene and alkylphenone homologous series, alcohols). Good linear correlation was obtained between either the micellar proportion, CLOGP50, or methylene selectivity and the phase composition for the mixed phases. Lipophilicity and methylene selectivity of the mixed LDS/LiPFOS PSPs can be calculated and can continuously be changed by mixing the two single phases (LDS and LiPFOS) in the appropriate (and calculable) portion. 相似文献
929.
Tushar S. Basu Baul Archana Mizar Giuseppe Ruisi Monique Biesemans 《Journal of organometallic chemistry》2009,694(14):2142-4247
Reactions of nBu2SnCl(L1) (1), where L1 = acid residue of 5-[(E)-2-(4-methoxyphenyl)-1-diazenyl]quinolin-8-ol, with various substituted benzoic acids in refluxing toluene, in the presence of triethylamine, yielded dimeric mixed ligand di-n-butyltin(IV) complexes of composition [nBu2Sn(L1)(L2-6)]2 where L2 = benzene carboxylate (2), L3 = 2-[(E)-2-(2-hydroxy-5-methylphenyl)-1-diazenyl]benzoate (3), L4 = 5-[(E)-2-(4-methylphenyl)-1-diazenyl]-2-hydroxybenzoate (4), L5 = 2-{(E)-4-hydroxy-3-[(E)-4-chlorophenyliminomethyl]-phenyldiazenyl}benzoate (5) and L6 = 2-[(E)-(3-formyl-4-hydroxyphenyl)-diazenyl]benzoate (6). All complexes (1-6) have been characterized by elemental analyses, IR, 1H, 13C and 117Sn NMR and 119Sn Mössbauer spectroscopy and their structures were determined by X-ray crystallography, complemented by 117Sn CP-MAS NMR spectroscopy studies in the solid state. The crystal structure of 1 reveals a distorted trigonal bipyramidal coordination geometry around the Sn-atom where the Cl- and N-atoms of ligand L1 occupy the axial positions. In complexes 2-5, the molecules are centrosymmetric dimers in which the Sn-atoms are connected by asymmetric μ-O bridges through the quinoline O-atom to give an Sn2O2 core. The differences in the Sn-O bond lengths within the bridge range from 0.28 to 0.48 Å, with the longer of the Sn-O distances being in the range 2.56-2.68 Å and the most symmetrical bridge being in 5. The carboxylate group is almost symmetrically bidentate coordinated to the tin atom in 5 (Sn-O distances of 2.327(2) and 2.441(2) Å), unlike the other complexes in which the distance of the carboxylate carbonyl O-atom from the tin atom is in the range 2.92-3.03 Å. The structure of 5 displays a more regular pentagonal bipyramidal coordination geometry about each tin atom than in 2-4. In contrast, the centrosymmetric dimeric structure of 6 involves asymmetric carboxylate bridges, resulting in a different Sn2C2O4 motif. The Sn-O bond lengths in the bridge differ by about 0.6 Å, with the longer distance involving the carboxylate carbonyl O-atom (2.683(2) and 2.798(2) Å for two molecules in the asymmetric unit). The carboxylate carbonyl O-atom has a second, even longer intramolecular contact to the Sn-atom to which the carboxylate group is primarily coordinated, with these Sn?O distances being as high as 3.085(2) and 2.898(2) Å. If the secondary interactions are considered, all the di-n-butyltin(IV) complexes (2-6) display a distorted pentagonal bipyramidal arrangement about each tin atom in which the n-butyl groups occupy the axial positions. 相似文献
930.
Nicolas Gauquelin Thomas E. Weirich Monica Ceretti Werner Paulus Michael Schroeder 《Monatshefte für Chemie / Chemical Monthly》2009,140(9):1095-1102
Abstract Long-term annealing of La2NiO4+δ single crystals at 1,273 K in air leads to the formation of nickel-rich Ruddlesden–Popper phases at the single-crystal surfaces.
Both the composition and the morphology of these phases depend on the surface orientation; whereas only crystallites of La4Ni3O10−δ were observed on (001) surfaces, both La3Ni2O7−δ and La4Ni3O10−δ were formed on (100) surfaces. The formation of the nickel-rich RP phases is believed to be due to surface segregation of
nickel or evaporation of a volatile lanthanum species. The crystallographic (001) planes inside the La3Ni2O7−δ and La4Ni3O10−δ crystallites were found to be oriented in the direction of preferential crystallite growth, which indicates that the diffusion
of lanthanum and nickel cations is faster along the crystallographic (001) planes than perpendicular to these planes.
Graphical abstract
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