introduction: herpes labialis is important in dentistry because of its high prevalence. herpes simplex virus (hsv) is responsive to treatment and infection control methods help protect patients and dental personnel. due to high levels of stress in the flight crew this study evaluated the prevalence of recurrent herpes labialis in the personnel of an airline company. materials and methods: in th...

Airline crew scheduling gives rise to many diicult and interesting optimisation problems. With straightforward approaches to the crew pairing problem one speciically needs to solve very large set-covering problems. One suggested approach to these problems is column generation. In column generation, the choice of master solver can have a signiicant impact on performance, both with respect to spe...

Train crew management involves the development of a duty timetable for each of the drivers (crew) to cover a given train timetable in a rail transport organization. This duty timetable is spread over a certain period, known as the roster planning horizon. Train crew management may arise either from the planning stage, when the total number of crew and crew distributions are to be determined, or...

A crew scheduling algorithms widely used in practice assume no disruptions. Because disruptions often occur, the actual cost of the resulting crew schedules is often greater. We consider algorithms for finding crew schedules that perform well in practice. The deterministic crew scheduling model is an approximation of crew scheduling under uncertainty with the assumption that all pairings will o...

Background Crew configuration in helicopter emergency medical service (HEMS) is a long debated topic. Different systems have seemingly good arguments for their choice of crew concept, but there is no solid scientific evidence available to support the benefit of any crew concept, especially in terms of medical benefit for the patient. To evaluate the rationale behind different crew compositions ...

The airline crew scheduling problem is the problem of assigning crew itineraries to flights. We develop a new approach for solving the problem that is based on enumerating hundreds of millions random pairings. The linear programming relaxation is solved first and then millions of columns with best reduced cost are selected for the integer program. The number of columns is further reduced by a l...

Crew scheduling is an important production planning of airlines. Being optimized crew scheduling could make full use of human resources, and reduce operating costs. The traditional airline crew scheduling model is deterministic and does not include potential disruptions due to weather, air traffic control, etc. To take into account of effects of random factors such as weather, air traffic contr...

In this paper, we propose a solution procedure for the Elementary Shortest Path Problem with Resource Constraints (ESPPRC). A relaxed version of this problem in which the path does not have to be elementary has been the backbone of a number of solution procedures based on column generation for several important problems, such as vehicle routing and crew-pairing. In many cases relaxing the restr...