Mixed logit modelling of airport choice in multi-airport regions

This paper presents an analysis of the choice of airport by air travellers departing from the San Francisco Bay (SF-B) area. The analysis uses the mixed multinomial logit model, which allows for a random distribution of tastes across decision makers. To our knowledge, this is the first application using this model form in the analysis of airport choice. The results indicate that there is significant heterogeneity in tastes, especially with respect to the sensitivity to access time, characterised by deterministic variations between groups of travellers (business/leisure, residents/visitors) as well as random variations within groups of travellers. The analysis reinforces earlier findings showing that business travellers are far less sensitive to fare increases than leisure travellers, and are willing to pay a higher price for decreases in access time (and generally also increases in frequency) than is the case for leisure travellers. Finally, the results show that the random variation between business travellers in terms of sensitivity to access time is more pronounced than that between leisure travellers, as is the case for visitors when compared to residents

Exploring the potential for cross-nesting structures in airport-choice analysis: A case-study of the Greater London area

The analysis of air-passengers’ choices of departure airport in multi-airport regions is a crucial component of transportation planning in many large metropolitan areas, and has been the topic of an increasing number of studies over recent years. In this paper, we advance the state of the art of modelling in this area of research by making use of a Cross-Nested Logit (CNL) structure that allows for the joint representation of inter-alternative correlation along the three choice dimensions of airport, airline and access-mode. The analysis uses data collected in the Greater London area, which arguably has the highest levels of inter-airport competition of any multi-airport region; the authors of this paper are not aware of any previous effort to jointly analyse the choice of airport, airline and access-mode in this area. The results of the analysis reveal significant influences on passenger behaviour by access-time, access-cost, flight-frequency and flight-time. A structural comparison of the different models shows that the cross-nested structure offers significant improvements over simple Nested Logit (NL) models, which in turn outperform the Multinomial Logit (MNL) model used as the base model

Dissipate locally, couple globally: a sharp transition from decoupling to infinite range coupling in Josephson arrays with on-site dissipation

We study the T=0 normal to superconducting transition of Josephson arrays with {\it on-site} dissipation. A perturbative renormalization group solution is given. Like the previously studied case of {\it bond} dissipation (BD), this is a "floating" to coupled (FC) phase transition. {\it Unlike} the BD transition, at which {\it only} nearest-neighbor couplings become relevant, here {\it all} inter-grain couplings, out to {\it infinitely} large distances, do so simultaneously. We predict, for the first time in an FC transition, a diverging spatial correlation length. Our results show the robustness of floating phases in dissipative quantum systems.Comment: 7+ pages, 3 eps figures, Europhysics Letters preprint format, as publishe

Substances Acting on the Central Nervous System. I. Derivatives of N-Acyl-2-phenylbutyramide

In search of compounds which may have hypnotic a!Ild sedative as well as anticonvulsant activi1ties, the N-a cyl-2-phenylbutyramides (X-XIVb) h ave been prepared. These sub.stances have been synthesized by trea ting the alkyl N-acyl iminoes.te r s with hydrochloric acid and the latter (X-XVaY by cond ensation of the iminoesters with appropriaite acyl chlorides

Substances Acting on the Central Nervous System. II. Derivatives of N-(a-bromoacyl)-2-phenylbutyramide

In connection with the investigation of substances acting on the central nervous system new N-substituted 2-phenylbutyramides (I-V) were synthesized. These amides were prepared by hydrolysis of the appropriate methyl N-substituted 2-phenyliminobutyrates (VI-IX)

Substances Acting on the Central Nervous System. I. Derivatives of N-Acyl-2-phenylbutyramide

In search of compounds which may have hypnotic a!Ild sedative as well as anticonvulsant activi1ties, the N-a cyl-2-phenylbutyramides (X-XIVb) h ave been prepared. These sub.stances have been synthesized by trea ting the alkyl N-acyl iminoes.te r s with hydrochloric acid and the latter (X-XVaY by cond ensation of the iminoesters with appropriaite acyl chlorides

Sulphur-containing Pantothenic Acid Derivatives

The synthesis of the mercapto analogue of pantothenic acid was effected by condensation of thiopantolactone III with ~-alanine. The required thiopantolactone was obtained by reduction of his (2,2-dimethyl-3-hydlvoxy-3-carboxypropyl) disulphide or by debenzylation of S-benzyl-2-hydroxy-4-mercapto-3,3-dimethyl butyric acid, the latter being prepared by condensaUon of pantolactone with sodium benzylmercaptide in dimethylformami,de

Decision-making for unmanned aerial vehicle operation in icing conditions

With the increased use of unmanned aerial systems (UAS) for civil and commercial applications, there is a strong demand for new regulations and technology that will eventually permit for the integration of UAS in unsegregated airspace. This requires new technology to ensure sufficient safety and a smooth integration process. The absence of a pilot on board a vehicle introduces new problems that do not arise in manned flight. One challenging and safety-critical issue is flight in known icing conditions. Whereas in manned flight, dealing with icing is left to the pilot and his appraisal of the situation at hand; in unmanned flight, this is no longer an option and new solutions are required. To address this, an icing-related decision-making system (IRDMS) is proposed. The system quantifies in-flight icing based on changes in aircraft performance and measurements of environmental properties, and evaluates what the effects on the aircraft are. Based on this, it determines whether the aircraft can proceed, and whether and which available icing protection systems should be activated. In this way, advice on an appropriate response is given to the operator on the ground, to ensure safe continuation of the flight and avoid possible accidents

Quantum rotor description of the Mott-insulator transition in the Bose-Hubbard model

We present the novel approach to the Bose-Hubbard model using the $\mathrm{U}(1)$ quantum rotor description. The effective action formalism allows us to formulate a problem in the phase only action and obtain an analytical formulas for the critical lines. We show that the nontrivial $\mathrm{U}(1)$ phase field configurations have an impact on the phase diagrams. The topological character of the quantum field is governed by terms of the integer charges - winding numbers. The comparison presented results to recently obtained quantum Monte Carlo numerical calculations suggests that the competition between quantum effects in strongly interacting boson systems is correctly captured by our model.Comment: accepted to PR