On air traffic flow management with rerouting. Part I: Deterministic case

In this paper a deterministic mixed 0-1 model for the air traffic flow management problem is presented. The model allows for flight cancelation and rerouting, if necessary. It considers several types of objective functions to minimize, namely, the number of flights exceeding a given time delay (that can be zero), separable and non-separable ground holding and air delay costs, penalization of alternative routes to the scheduled one for each flight, time unit delay cost to arrive to the nodes (i.e., air sectors and airports) and penalization for advancing arrival to the nodes over the schedule. The arrival and departure capacity at the airports is obviously considered, as well as the capacity of the different sectors in the airspace, being allowed to vary along the time horizon. So, the model is aimed to help for better decision-making regarding the ground holding and air delays imposed on flights in an air network, on a short term policy for a given time horizon. It is so strong that there is no additional cut appending, nor does it require the execution of the branch-and-bound phase to obtain the optimal solution for the problem in many cases of the testbeds with which we have experimented. In the other cases, the help of the cut identifying and heuristic schemes of the state-of-the art optimization engine of choice is required in order to obtain the solution of the problem, and the branch-and-bound phase is not required either. An extensive computational experience is reported for large-scale instances, some of which have been taken from the literature and some others were coming from industry.     

Multi-peak solutions for the Hénon equation with slightly subcritical growth

We study the Dirichlet problem for the Hénon equation

Ground and excited states calculations of 7-phenylamino-substituted coumarins

A theoretical calculation of the ground and first excited states of two 7-phenylamino-substituted coumarin compounds are performed. In order to study the effect of phenyl substituted in amino group and fluorine atoms substituted in methyl group, 7-amino-4-methyl coumarin (C120) and 7-amino-4-(trifluoromethyl) coumarin (C151) were also studied. The geometries of the ground state and the first ground state were optimized using density function theory and configuration interaction singles levels of theory. Molecular orbitals (MO) of the ground and first excited states of the four coumarin compounds were obtained to explain the change of the structures. ZINDO and TD-DFT methods with different basis sets were applied to predict the UV absorption spectra. The solvent effect had also been taken into account using self-consistent isodensity polarized continuum model. The predicted spectra are in agreement with the experimental data.     

离子色谱法测定地表水中阴离子的研究

建立了离子色谱体系测定地表水中无机阴离子的方法。研究了离子色谱仪的各项工作条件,建立了有效的样品处理方法。以固体邻苯二甲酸和碳酸钠处理样品,百里酚酞作指示剂,用ＤＩＯＮＥＸ ＡＳ４Ａ－ＳＣ阴离子分析柱及电导检测器测定无机阴离子,变化色谱体系以满足不同样品测定的要求。方法操作简便、测定快速,已成功地用于地表水样测定,结果满意。     

Stability and instability of standing waves to a system of Schrödinger equations with combined power-type nonlinearities

We obtain the existence of standing wave solutions to a coupled nonlinear Schrödinger system

     

The relation between structure and reactivity in five-membered heteroaromatic compounds—II: CNDO/2 calculations on azolium cations and on the zwitterions resulting from their deprotonation

Olofson's group and Norris and Henry have reported proton exchange rates for a variety of azolium cations in aqueous solution. They found that ring protons in positions located α- to pyrrole-type N atoms exchange much faster than those located β- to such nitrogens, and that addition of pyridine-type nitrogen to the ring also caused a large increase in rate of exchange. This report describes the results of CNDO/2 calculations on azolium cations representative of those studied experimentally, and on the zwitterions resulting from the deprotonation of these cations. The calculated vapor-phase energies of deprotonation are in agreement with the structure-reactivity trends summarized above, but the calculated effect of added nitrogen is unexpectedly small relative to the effect of interchanging α- and β- pyrrole-type N atoms. The calculated charge distributions and one- and two-atom contributions to the calculated energies of deprotonation are analyzed in terms of classical organic mechanisms for transmission of substituent effects. The results of this analysis suggest that the relative reactivities of isomeric tetrazolium cations are determined primarily by coulombic effects, but that relative reactivities of isomeric positions in the imidazolium and pyrazolium series are apparently determined primarily by inductive and hybridization effects. π-Electron resonance (contributions from carbenoid resonance forms) is apparently not of overriding importance. When nitrogen is added to the ring in an α-position relative to the CH group undergoing exchange, the resulting increase in CH acidity seems to be due to inductive and hybridization effects, partially offset by a coulombic effect due to the negative charge on the added nitrogen. If classical σ-inductive and hybridization effects from an added β-nitrogen are at all influential, they seem much less so than from an added α-nitrogen; thus according to CNDO/2 these effects alone apparently cannot explain the observed large rate increase due to added β-nitrogen. The possible importance of solvent effects, delocalization of the added negative charge into the σ-framework and coulombic effects due to the added nitrogen are discussed.     

Classical ground states in one dimension

We give conditions on an interaction sufficient to guarantee that in one dimension it yield a periodic ground state with one or two particles per unit cell.Research supported in part by NSF Grant MCS 81-01596-A01.