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Speaking Stata: MMXI and all that: Handling Roman numerals within Stata

Cox, Nicholas - In: Stata Journal 11 (2011) 1, pp. 126-142

The problem of handling Roman numerals in Stata is used to illustrate issues arising in the handling of classification codes in character string form and their numeric equivalents. The solutions include Stata programs and Mata func- tions for conversion from numeric to string and from string to...

Persistent link: https://www.econbiz.de/10008862275

Unbinding transitions of membranes and strings from single and double-well potential

Asfaw, Mesfin - In: Physica A: Statistical Mechanics and its Applications 387 (2008) 14, pp. 3526-3536

strings. We derive the scaling laws for strings analytically. The exact analytical results provide scaling estimate for …

Persistent link: https://www.econbiz.de/10010590246

On non-extensive statistics, chaos and fractal strings

Castro, C. - In: Physica A: Statistical Mechanics and its Applications 347 (2005) C, pp. 184-204

-extensive statistics (with a non-additive q-entropy) of an ensemble of fractal strings and branes of different dimensionalities. Non …-extensive entropy and probability distribution of a canonical ensemble of fractal strings and branes is studied in terms of their …-particles, knot theory, quantum groups and number theory are briefly discussed within the framework of fractal strings and branes. …

Persistent link: https://www.econbiz.de/10010590675

Speaking Stata: On getting functions to do the work

Cox, Nicholas J. - In: Stata Journal 2 (2002) 4, pp. 411-427

Functions in Stata take two main forms, built-in functions that are part of the executable and egen functions written in Stata's own language. These are surveyed, giving a variety of tips and tricks, and noting the large number of user-written egen functions available for download from the...

Persistent link: https://www.econbiz.de/10005583262

Optimal reefer slot conversion for container freight transportation

Wang, Kai; Liu, Weiwei; Wang, Shuaian; Liu, Zhiyuan - In: Maritime policy and management : MPM 44 (2017) 5/6, pp. 727-743

Persistent link: https://www.econbiz.de/10011817759

Improvements to a large neighborhood search heuristic for an integrated aircraft and passenger recovery problem

Sinclair, Karine; Cordeau, Jean-François; Laporte, Gilbert - In: European Journal of Operational Research 233 (2014) 1, pp. 234-245

Because most commercial passenger airlines operate on a hub-and-spoke network, small disturbances can cause major disruptions in their planned schedules and have a significant impact on their operational costs and performance. When a disturbance occurs, the airline often applies a recovery...

Persistent link: https://www.econbiz.de/10010709945

An Optimization Model for the Simultaneous Operational Flight and Pilot Scheduling Problem

Mirela Stojkovi\'{c}; Soumis, François - In: Management Science 47 (2001) 9, pp. 1290-1305

This paper describes and solves the operational pilot scheduling problem for one day of operations. The problem consists in simultaneously modifying, as necessary, the existing flight departure schedules and planned individual work days (duties) while keeping planned aircraft itineraries...

Persistent link: https://www.econbiz.de/10009191858

Incorporating aircraft efficiency measures into the tail assignment problem

Lapp, Marcial; Wikenhauser, Florian - In: Journal of Air Transport Management 19 (2012) C, pp. 25-30

We present an optimization framework that minimizes aircraft fuel consumption and emissions through a redesigned tail assignment process. In this fleet specific aircraft assignment, we reallocate aircraft such that fuel efficiency is matched with the fuel productivity of a line-of-flight. We...

Persistent link: https://www.econbiz.de/10010682370

Using deficit functions for aircraft fleet routing

Stern, Helman I.; Gertsbakh, Ilya B. - In: Operations Research Perspectives 6 (2019), pp. 1-11

We consider the problem of minimizing the number of airplanes needed to fly a fixed daily repeating schedule of flights. We use deficit functions (DF) to decompose an aviation schedule of aircraft flights into aircraft chains (routes) called a chain decomposition. Each chain visits periodically...

Persistent link: https://www.econbiz.de/10012662780

Improving Airline Network Robustness and Operational Reliability by Sequential Optimisation Algorithms

Wu, Cheng-Lung - In: Networks and Spatial Economics 6 (2006) 3, pp. 235-251

A sequential optimisation algorithm is developed to improve the operational reliability of airline schedules. Simulation results show that departure delays are reduced by 30% after optimisation by using extra 260 min buffer times in the schedule. This also increases the network-wide schedule...

Persistent link: https://www.econbiz.de/10005698777