An integrated decision support tool for airlines schedule recovery during irregular operations

This paper presents a decision support tool for airlines schedule recovery during irregular operations. The tool provides airlines control centers with the capability to develop a proactive schedule recovery plan that integrates all flight resources. A rolling horizon modeling framework, which integrates a schedule simulation model and a resource assignment optimization model, is adopted for this tool. The schedule simulation model projects the list of disrupted flights in the system as function of the severity of anticipated disruptions. The optimization model examines possible resource swapping and flight re-quoting to generate an efficient schedule recovery plan that minimizes flight delays and cancellations. A detailed example that illustrates the application of the tool to recover the schedule of a major US air-carrier during a hypothetical ground delay program scenario is presented. The results of several experiments that illustrates overall model performance in terms of solution quality and computation experience are also given.     

Synthesis and Diels-Alder Reactions of a New Kind of Chiral Dienophiles: Cyclic Vinyl-p-tolylsulfilimines

A new kind of chiral dienophiles, cyclic vinyl-p-tolylsulfilimines (2a and 2b), were obtained from the corresponding (Z)-sulfinylacrylonitriles with HBF(4) and methanol. The asymmetric Diels-Alder reaction of optically pure 2a with cyclopentadiene under mild thermal or catalyzed conditions afforded only the endo-4a adduct with complete endo and pi-facial selectivities. The ability of the sulfilimine moiety to enhance the dienophilic reactivity of the double bond is similar to that of the sulfinyl group.     

Phase diagrams of lyotropic cholesteric fluids

Experimental investigations of lyotropic cholesterics fluids are presented which show that changes in the shape anisotropy and chirality of the micellar population determine the topology of the temperature-concentration phase diagrams. For given amounts of the substances which induce the chirality and modify the shape anisotropy of the micelles, two distinct biaxial cholesteric phases are disclosed in the phase diagrams. This is interpreted in the framework of the catastrophe theory of phase transitions.     

UV-visible and infrared absorption spectra of gamma irradiated CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses: A comparative study

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV-visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV bands due to combined absorption of trace iron impurities and divalent lead ions. The CuO-doped glasses reveal an extra broad visible band due to Cu²⁺ ions in octahedral coordination. The effects of gamma irradiation have been analyzed for both the sharing of all constituent components including trace iron impurities. Infrared absorption spectra of the prepared samples were investigated by the KBr disk technique. The FTIR spectra reveal main characteristic absorption bands due to different phosphate groups. The IR spectra are observed to be slightly affected by the increase of CuO in the doping level (0.2-3%) indicating the stability of the main network units.     

Ride matching and vehicle routing for on-demand mobility services

Journal of Heuristics - On-Demand Mobility Services (ODMS) have gained considerable popularity over the past few years. Travelers use mobile phone applications to easily request a ride, update trip...