This paper investigates the air traffic controller scheduling problem in which each employee must be assigned up to 10 shifts over a two-week planning horizon. Additional assignments include a 30-minute lunch break an...
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This paper investigates the air traffic controller scheduling problem in which each employee must be assigned up to 10 shifts over a two-week planning horizon. Additional assignments include a 30-minute lunch break and several 15-minute rest breaks within each shift. The goal is to select the minimum number of employees that balances a weighted combination of demand undercoverage, overcoverage and labor costs. Additional constraints include the minimum/maximum number of employees, minimum shift and demand coverage, minimum number of consecutive working hours, bounds on working hours, minimum days off, maximum consecutive days on, and minimum rest time between shifts. A 2-phase algorithm is developed to efficiently construct weekly schedules for the controllers. In Phase 1, employee-shift assignments are made with a randomization algorithm and a greedy post-processor. In Phase 2, 15-minute breaks are added to the selected shifts by solving a second optimization model. The proposed methodology is tested on both small instances defined by the Federal Aviation Administration in their 2022 challenge, and large instances with up to 52 employees. Compared to the actual schedule, the results verify that the 2-phase algorithm offers significantly better schedules with respect to all metrics. We conclude with a parametric analysis of the number of employees to determine how staffing levels effect solution quality.
To reduce peak-to-average power ratio, we propose a method of choosing suitable vectors in a partial transmit sequence technique. Conventional approaches require that a suitable vector be selected from a large number ...
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To reduce peak-to-average power ratio, we propose a method of choosing suitable vectors in a partial transmit sequence technique. Conventional approaches require that a suitable vector be selected from a large number of candidates. By contrast, our method does not include such a selecting procedure, and instead generates random vectors from the Gaussian distribution whose covariance matrix is a solution of a relaxed problem. The suitable vector is chosen from the random vectors. This yields lower peak-to-average power ratio than a conventional method.
Aim: Randomized trials are very challenging to perform in rare cancers such as gastro-enteropancreatic neuroendocrine carcinomas. We hypothesized that the randomized BEVANEC trial of FOLFIRI + /- bevacizumab could hav...
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The evolutionary response to interspecific competition is the partitioning of the resources used by the competing species. At the community level, the ultimate outcome of resource partitioning determines how communiti...
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The evolutionary response to interspecific competition is the partitioning of the resources used by the competing species. At the community level, the ultimate outcome of resource partitioning determines how communities evolve in terms of their species composition, explaining the distribution and abundance of organisms within natural assemblages. Despite amphibians having attracted considerable attention from population biologists, niche partitioning patterns have never been explored with a systematic approach in tailed amphibians (order Urodela). To fill this gap we tested whether Urodela communities are assembled in a non-random fashion along the trophic niche and which determinants (environmental factors and interspecific interactions) explained the observed patterns. We used a suite of statistical tools, including Generalized Linear Models and Null Models with Monte Carlo simulations, in order: (1) to explore the occurrence of non-random assemblage structure among the Urodela communities, and (2) to test environmental features (habitat) and interspecific interactions (exemplified by the overlap in species' body size) as predictors of non-random assemblage composition. Our systematic review pointed out that: (1) the evolution of non-random structure in Urodela assemblages was determined by both biotic and abiotic factors, and (2) the food niche plays a key role in the coexistence of Urodela syntopic species. The considered assemblages showed a non-random structure influenced by diet, habitat and morphological features acting in an interactive fashion. Lawlor's RA2 algorithm was more effective than any other randomization algorithms to reveal community structure based on interspecific competition. The assemblage structure was influenced by the niche breadth of the species in the generalist-specialist nature of the resource utilization: the much higher the niche breadth similarity among species, the most likely was a non-random structure in the assemblage. In an aq
In this paper, we study the problem of minimizing the cost for a set of multicommodity traffic request R in an undirected network G(V,E). Motivated by the energy efficiency of communication networks, we will focus on ...
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ISBN:
(纸本)9783319080161;9783319080154
In this paper, we study the problem of minimizing the cost for a set of multicommodity traffic request R in an undirected network G(V,E). Motivated by the energy efficiency of communication networks, we will focus on the case where the objective is to minimize Sigma(e)(l(e))(2). Here l(e) represents the load on the edge e. For this problem, we propose an oblivious routing algorithm, whose decisions don't rely on the current traffic in the network. This feature enables our algorithm to be implemented efficiently in the high-capacity backbone networks to improve the energy efficiency of the entire network. The major difference between our work and the related oblivious routing algorithms is that our approach can satisfy the integral constraint, which does not allow splitting a traffic demand into fractional flows. We prove that with this constraint no oblivious routing algorithm can guarantee the competitive ratio bounded by o(|E|(1/3)). By contrast, our approach gives a competitive ratio of O(|E|(1/2)log(2) |V|.log D, where D is the maximum demand of the traffic requests. This competitive ratio is tight up to O (|E|(1/6)log(2)|V|.log(D)).
The Coordinating Centre (CC) of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico (GISSI) used telecommunication technology to develop a computerized network system for the data managem...
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The Coordinating Centre (CC) of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico (GISSI) used telecommunication technology to develop a computerized network system for the data management of the GISSI studies. Through a personal computer (PC), a communication program, a modem and a telephone line, the investigator in each participating centre can connect with a micro-computer at the CC, to recruit/randomize patients and download reports on the progress of the trial. In the first case? the investigator is required to answer a set of predefined questions, and thereby the system automatically checks eligibility criteria and randomly assigns the patient to a treatment arm. In the second case, once the investigator has made a choice from a list of standard reports and the relative query on CC central database, the generation, the formatting and the transfer of the selected report to the PC are executed automatically on line. The main advantages of this system are a reduction in number of mistakes in data completion and in the human and economic resources required, as well as the real time updating of participating centres. The system was successfully adopted in the GISSI-3 trial (200 Coronary Care Units and 19 394 patients enrolled), in the European arm of the CORE trial and it is currently being used in the GISSI-Prevenzione trial. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.
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