Forest Management Zone Design with a Tabu Search Algorithm

Increased conflicts between timber production and environmental protection led some analysts to advocate land-use segregation, often referred to as forest management zoning. The objective of zoning is to create ecologically desirable non-fragmented forest reserves and group timber production areas. We formulate an integer programming model of forest zoning that explicitly addresses clustering of spatial units allocated to timber production and reserve zones while also promoting separation of these zones. A tabu search algorithm is developed, implemented and tested using a case study. The case study results indicate that up to 5% of the net financial return is sacrificed with a 'satisfactory' grouping of units within each zone. A 'good' separation between the reserves and timber production zone is achieved at the cost of further decline of the net financial return up to 11% relative to the unconstrained case.forest planning, integer programming, reserves, tabu search, timber production, zoning

Satellite downlink scheduling problem: A case study

The synthetic aperture radar (SAR) technology enables satellites to efficiently acquire high quality images of the Earth surface. This generates significant communication traffic from the satellite to the ground stations, and, thus, image downlinking often becomes the bottleneck in the efficiency of the whole system. In this paper we address the downlink scheduling problem for Canada's Earth observing SAR satellite, RADARSAT-2. Being an applied problem, downlink scheduling is characterised with a number of constraints that make it difficult not only to optimise the schedule but even to produce a feasible solution. We propose a fast schedule generation procedure that abstracts the problem specific constraints and provides a simple interface to optimisation algorithms. By comparing empirically several standard meta-heuristics applied to the problem, we select the most suitable one and show that it is clearly superior to the approach currently in use.Comment: 23 page

Waiting strategies for the dynamic pickup and delivery problem with time windows

The dynamic pickup and delivery problem with time windows arises in courier companies making same-day pickup and delivery of letters and small parcels. In this problem solution quality is affected by the way waiting time is distributed along vehicle routes. This article defines and compares four waiting strategies. An extensive empirical study is carried out on instances generated using real-life data.

Forest Management Zone Design with a Tabu Search Algorithm

Increased conflicts between timber production and environmental protection led some analysts to advocate land-use segregation, often referred to as forest management zoning. The objective of zoning is to create ecologically desirable non-fragmented forest reserves and group timber production areas. We formulate an integer programming model of forest zoning that explicitly addresses clustering of spatial units allocated to timber production and reserve zones while also promoting separation of these zones. A tabu search algorithm is developed, implemented and tested using a case study. The case study results indicate that up to 5% of the net financial return is sacrificed with a 'satisfactory' grouping of units within each zone. A 'good' separation between the reserves and timber production zone is achieved at the cost of further decline of the net financial return up to 11% relative to the unconstrained case

Age as a prognostic factor in skin melanoma

The aim of this study was to establish whether older patients with skin melanoma (in an analyzed group of 189 patients treated at the Institute for Oncology and Radiology of Serbia from 2004 to 2008), have worse survival compared to younger patients. In 100 men and 89 women with an average age of 58.9 years, the following parameters were observed and statistically analyzed in SPSS: gender, age, localization, tumor thickness, ulceration, lymphonodal status and invasion level. In the four age subgroups - quartiles, the best survival was shown in patients <50 years (85.7%), and the worst in patients >70 years (76.1%). Patients without ulcerations, with negative lymph nodes, thin melanomas and Clark levels I and II had significantly better survival outcomes. Although the results showed no statistical significance of age as a prognostic factor in the survival of patients with skin melanoma, further research on a larger number of patients is warranted