The vehicle routing problem with flexible time windows and traveling times

We generalize the standard vehicle routing problem by allowing soft time window and soft traveling time constraints, where both constraints are treated as cost functions. With the proposed generalization, the problem becomes very general. In our algorithm, we use local search to determine the routes of vehicles. After fixing the route of each vehicle, we must determine the optimal start times of services at visited customers. We show that this subproblem is NP-hard when cost functions are general, but can be efficiently solved with dynamic programming when traveling time cost functions are convex even if time window cost functions are non-convex. We deal with the latter situation in the developed iterated local search algorithm. Finally we report computational results on benchmark instances, and confirm the benefits of the proposed generalization.     

Ring opening of cyclic ethers by sulfuric acid ‐ acetic anhydride

Cyclic ethers such as tetrahydrofuran or tetrahydropyran were easily cleaved at room temperature by sulfuric acid ‐ acetic anhydride providing the corresponding diacetoxyalkanes in good yield. The ring opening was applicable to saturated cyclic ethers, regardless of the presence of substituent groups.     

Reaction of α,β‐unsaturated ketones using cerium (IV) sulfate tetrahydrate in acetic acid

The reaction of α,β‐unsaturated ketones with cerium (IV) sulfate tetrahydrate [Ce(SO₄)₂·4H₂O, CS] in acetic acid gave the corresponding β‐acetoxy ketones. In the case of 2‐cyclohexen‐1‐one with CS in acetic acid, benzobicyclo[2.2.2]octen‐2‐one was obtained. The reaction mechanism also was proposed. Moreover, we report the aromatization and esterification of (R)‐(?)‐carvone by CS in acetic acid. Copyright © 2007 John Wiley & Sons, Ltd.     

Abel inversion of axially-symmetric shock wave flows

Finite-fringe interferograms produced for axisymmetric shock wave flows are analyzed by Fourier transform fringe analysis and an Abel inversion method to produce density field data for the validation of numerical models. For the Abel inversion process, we use basis functions to model phase data from axially-symmetric shock wave structure. Steady and unsteady flow problems are studied, and compared with numerical simulations. Good agreement between theoretical and experimental results is obtained when one set of basis functions is used during the inversion process, but the shock front is smeared when another is used. This is because each function in the second set of basis functions is infinitely differentiable, making them poorly-suited to the modelling of a step function as is required in the representation of a shock wave.Received: 12 November 2003, Accepted: 21 October 2004, Published online: 31 March 2005[/PUBLISHED]PACS: 47.40.-x, 42.40.Kw, 02.30.Zz     

Probing interaction of paramagnetic electron with conduction electrons in high Tc superconductor LaSrCuO by (μ-O) spin relaxation

The paramagnetic (μ^-O) state formed at the oxygen site in high T_c LaSrCuO was used to probe an interaction between the localized moment of the paramagnetic electron and the conduction electrons via zero field μ^- spin relaxation. The enhanced relaxation rates consistently observed in the superconducting state of various Sr concentrations are explained as an effect of spin‐pairing in the high T_c supercurrent. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis, characterization and crystal structure of a 6,8,15,17-tetramethyldibenzo [b,i] (1,4,8,11)tetraaza (14)-annulene yttrium (III) complex

In this study, the sandwich complex of tmtaa, Y(tmtaa) (Htmtaa)·2THF (H₂tmtaa=6,8,15,17-tetramethyldibenzo [b,i] , respectively. The distances of the yttrium to the planes of the 4 nitrogen atoms for tmtaa and Htmtaa are 1.44 (2) and 1.51 (2) Å, respectively.     

Preparation and Water Droplet Sliding Properties of Transparent Hydrophobic Polymer Coating by Molecular Design for Self-Organization

Transparent hydrophobic polymer coating was prepared from methacrylate copolymer with molecular modeling in order to improve hydrophobicity and durability. Organic-inorganic hybridization improved the durability of the thin films. Furthermore the control of hydrophobicity and water droplet sliding properties of the flat coating was successfully performed. Water droplet sliding angle depended on the chemical structure of the materials, not on the hydrophobicity, while sliding motion simply depended on the hydrophobicity.     

Admissible minimax estimators of a mean vector of scale mixtures of multivariate normal distributions

The problem of estimating a mean vector of scale mixtures of multivariate normal distributions with the quadratic loss function is considered. For a certain class of these distributions, which includes at least multivariate-t distributions, admissible minimax estimators are given.     

Determination of mono-, di- and tri-substituted butyltin,phenyltin and methyltin compounds as free halides using gas chromatography with flame photometric detection

A simple chromatographic procedure has been developed for the sensitive determination of mono-, di- and tri-substituted butyltin, phenyltin, and methyltin compounds as halides. The organotin compounds were separated on a DB-1 capillary column and detected by flame photometric detection (FPD) equipped with a 611.5 nm filter. Pretreatment of the capillary column with an ethyl acetate solution of hydrobromic acid, or doping of standard solutions with hydrobromic acid, was found to be necessary if reproducibly sharp peaks of organotin halides were to be obtained. Column treatment and acid doping did not cause any background problems or undesirable degradation of the organotin compounds. Three different standard solutions in ethyl acetate had to be Jrepared, because undesirable degradation of the organotin halides was observed when all the compounds were dissolved in the same solution. The first, standard solution I, contained tri-n-butyltin chloride (TBTCI) and trimethyltin chloride (TMTCI), the second, standard solution II, contained triphenyltin chloride (TPTCI), and the third, standard solution III, contained hydrogen bromide and the other organotin compounds: di-n-butyltin chloride (DBTCI), mono-n-butyltin chloride (MBTCI), dimethyltin chloride (DMTCI), monomethyltin chloride (MMTCI), diphenyltin chloride (DPTCI), and monophenyltin chloride (MPTCI). An ethyl acetate solution containing hydrobromic acid (20 × 10^?3 mol/I) was used for column treatment.     

Cationic cyclopolymerization of new divinyl ethers: The effect of ether and ester neighboring functional groups on their cyclopolymerization tendency

The cationic polymerization of two new divinyl ethers, 1‐(2‐vinyloxyethoxy)‐2‐[(2‐vinyloxyethoxy)carbonyl]benzene ( 2 ) and 1,2‐bis[(2‐vinyloxyethoxy)carbonyl]benzene ( 3 ), as well as 1,2‐bis(2‐vinyloxyethoxy)benzene ( 1 ), with BF₃OEt₂ in CH₂Cl₂ at 0 °C at low initial monomer concentrations ([M]₀ = 0.15 and 0.075 M) gave soluble polymers with relatively high molecular weights and broad molecular weight distributions (MWDs), whereas reactions with the HCl/ZnCl₂ initiating system yielded soluble polymers with relatively narrow MWDs (weight‐average molecular weight/number‐average molecular weight ? 1.6) under similar reaction conditions. An NMR structural analysis of the HCl/ZnCl₂‐mediated polymers from the divinyl ethers showed that poly( 1 ) had virtually no unreacted vinyl ether groups throughout the polymerization (monomer conversion = 28–98%), whereas poly( 2 ) and poly( 3 ) possessed some amount of unreacted vinyl ether groups in the initial stage of the polymerization; the content of the vinyl groups of poly( 2 ) was 18 mol % at a 15% monomer conversion, and the content of the vinyl groups of poly( 3 ) was 31 mol % at an 18% monomer conversion. Therefore, divinyl ether 1 underwent cyclopolymerization exclusively to give almost completely cyclized polymers [degree of cyclization (DC) ～ 100%], whereas divinyl ethers 2 and 3 exhibited a lower cyclopolymerization tendency [DC for poly( 2 ) = 82%; DC for poly( 3 ) = 69%]. The differences in the cyclopolymerization tendencies among the divinyl ethers can be explained by the differences in the solvation powers of the neighboring functional groups adjacent to the vinyl ether moiety with the active center: the ether oxygen of the ether neighboring group solvates intramolecularly with the active center to accelerate the intramolecular propagation, but such an interaction is less effective with the more electron‐deficient oxygen attached to the carbonyl group of the ester neighboring group. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 281–292, 2003