The airline industry is notably one of the success stories with respect to the use of optimization based methods and tools in planning. Both in planning of the assignment of available aircraft to flights and in crew scheduling, these methods play a major role.Plans are usually made several months prior to the actual day of operation. As a consequence, changes often occur in the period from the construction of the plan to the day of operation. Optimization tools play an important role also in handling these changes.However, at the day of operation, no planning tool have been able to cope with the complexity of the re-planning given that the time span for proposing a solution is only a few minutes. Numerous suggestions for such subsystems have been put forward, but today no general tool is able to handle aircraft, crew, and passenger concurrently in a single system. Currently, there is a gap between the reality faced in operations control and the decision support offered by the commercial it-systems targeting the recovery process. Though substantial achievements have been made with respect to solution methods, and hardware has become much more powerful, even the most advanced prototype systems for integrated recovery have severe limitations.The current review accounts for the majority of subsystems mentioned in the literature in terms of the sub-problem addressed and the method used in each particular contribution. For each proposed system, also the computational experiments supporting the practical usability of the system is reported.

Over the past decade, cross-docking has emerged as an important material handling technology in transportation. A variation of the well-known Vehicle Routing Problem (VRP), the Vehicle Routing Problem with Cross-Docking (VRPCD) arises in a number of logistics planning contexts. This paper addresses the VRPCD, where a set of homogeneous vehicles are used to transport products from the suppliers to the corresponding customers via a cross-dock. The products can be consolidated at the cross-dock but cannot be stored for very long because the cross-dock does not have longterm inventory-holding capabilities. The objective of the VRPCD is to minimize the total traveled distance while respecting time window constraints at the nodes and a time horizon for the whole transportation operation. In this paper, a mixed integer programming formulation for the VRPCD is proposed. A tabu search heuristic is embedded within an adaptive memory procedure to solve the problem. The proposed algorithm is implemented and tested on data sets provided by the Danish consultancy Transvision, and involving up to 200 pairs of nodes. Experimental results show that this algorithm can produce high quality solutions (less than 5% away from optimal solution values) within very short computational time.

The aim of the present study was to evaluate the influence of menstruation, method of contraception, and iron supplementation on iron status in young Danish women, and to assess whether iron deficiency could be predicted from the pattern of menstruation. Iron status was examined by measuring serum (S-) ferritin and hemoglobin (Hb) in 268 randomly selected, healthy, menstruating, nonpregnant Danish women aged 18-30 years. Iron deficiency (S-ferritin <16 microg/l) was observed in 9.7%, of the women, iron deficiency anemia (S-ferritin < 13 microg/l and Hb < 121 g/l) in 2.2%. Iron supplementation, predominantly as vitamin-mineral tablets containing 14-20 mg of ferrous iron was used by 35.1%. The median serum ferritin was similar in non-iron users and in iron users, whereas the prevalence of iron deficiency was 12.6% in nonusers vs. 4.3% in users, the prevalence of iron deficiency anemia 3.4% in nonusers vs. 0%, in users (p=0.17) In non-iron-supplemented women, S-ferritin levels were inversely correlated with the duration of menstrual bleeding (rs= -0.25, p<0.001) and with the women's assessment of the intensity of menstrual bleeding (r(s)= -0.27, p<0.001), whereas no such correlations were found in iron-supplemented women. The results demonstrate that even moderate daily doses of ferrous iron can influence iron status in women with small iron stores. Women using hormonal contraceptives had menstrual bleeding of significantly shorter duration than those using intrauterine devices (IUD) or other methods. There was a high prevalence of small and absent body iron stores in young women, suggesting that preventive measures should be focused on those women whose menstruation lasts 5 days or longer, who have menstrual bleeding of strong intensity, who use an IUD without gestagen, and who are blood donors.

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An exact solution method for the graph bisection problem is presented. We describe a branch-and-bound algorithm which is based on a cutting plane approach combining semide nite programming and polyhedral relaxations. We report on extensive numerical experiments which were performed for various classes of graphs. The results indicate that the present approach solves general problem instances with 80 90 vertices exactly in reasonable time, and provides tight approximations for larger instances. Our approach is particularly well suited for special classes of graphs as planar graphs and graphs based on grid structures.

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The Manpower Allocation Problem with Time Windows, Job-Teaming Constraints and a limited number of teams (m-MAPTWTC) is a crew scheduling problem faced in several different contexts in the industry. The number of teams is predetermined and hence the objective is to create a schedule that will maximize utilization by leaving as few tasks uncompleted as possible. The schedule must respect working hours of the teams, transportation time between locations, and skill requirements and time windows of the tasks. Furthermore, some tasks are completed by multiple cooperating teams. Cooperating teams must initiate work simultaneously and hence this must be maintained in the schedule. The problem is solved using column generation and Branch-and-Bound. Optimal solutions are found in 11 of 12 test instances originating from real-life problems. The paper illustrates a way to exploit the close relations between scheduling and vehicle routing problems. The formulation as a routing problem gives a methodological benefit, leading to optimal solutions. A constraint on synchronization is imposed and successfully dealt with in the branching scheme.

Reducing snails and trematode eggs in nursery ponds lowered trematode transmission among fish.