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1

The SEKO assignment : efficient and fair assignment of students to multiple seminars

Hoßfeld Tobias

Operations Research and Decisions

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2023

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Vol. 33, No. 3

1--25

EN

Seminars are offered to students for education in various disciplines. The seminars may be limited in terms of the maximum number of participants, e.g., to have lively interactions. Due to capacity limitations, those seminars are often offered several times to serve the students’ demands. Still, some seminars are more popular than others and it may not be possible to grant access to all interested students due to capacity limitations. In this paper, a simple, but efficient random selection using key objectives (SEKO) assignment strategy is proposed which achieves the following goals: (i) efficiency by utilizing all available seminar places, (ii) satisfying all students by trying to assign at least one seminar to each student, and (iii) fairness by considering the number of assigned seminars per student. We formulate various theoretical optimization models using integer linear programming (ILP) and compare their solutions to the SEKO assignment based on a real-world data set. The real-world data set is also used as the basis for generating large data sets to investigate the scalability in terms of demand and number of seminars. Furthermore, the first-in first-out (FIFO) assignment, as a typical implementation of fair assignments in practice, is compared to SEKO in terms of utilization and fairness. The results show that the FIFO assignment suffers in realworld situations regarding fairness, while the SEKO assignment is close to the optimum and scales regarding computational time in contrast to the ILP.

2

Flow Aggregation for Energy-Aware Ad-Hoc Wireless Networks Respecting QoS Provisions

Boukrim Mustapha, Antari Jilali

Journal of Telecommunications and Information Technology

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2020

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nr 1

31--38

EN

Emerging communication technologies are now leading developers to design IT systems taking into count their energy-related considerations. Much research performed in the area of ad-hoc wireless networks tends to distribute the ﬂows over all nodes of the network, which increases the amount of energy consumed by each node and reduces longevity of the network. To overcome these problems, this paper seeks to aggregate a set of ﬂows within a number of nodes that is as low as possible in order to be capable of routing those ﬂows. This proposal allows to maximize the number of network nodes that may be turned oﬀ. The proposed solution was formulated as an integer linear programming (ILP) problem using a set of energy and quality of service (QoS) constraints. This formulation minimizes the total energy consumed by the nodes to construct a topology network that is capable of meeting QoS requirement for a set ﬂows inserted into the network. To evaluate the eﬃciency of the proposed model, a performance-based comparison was conducted with another routing model. The simulation results show that the proposed model oﬀers better performance in terms of global energy consumption and network load.

3

Fairness considerations with algorithms for elastic traffic routing

Cinkler T., Laborczi P., Pióro M.

Journal of Telecommunications and Information Technology

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2004

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nr 2

3-12

EN

The bit rate of modern applications typically varies in time. We consider the traffic elastic if the rate of the sources can be controlled as a function of free resources along the route of that traffic. The objective is to route the demands optimally in sense of increasing the total network throughput while setting the rates of sources in a fair way. We propose a new fairness definition the relative fairness that handles lower and upper bounds on the traffic rate of each source and we compare it with two other known fairness definitions, namely, the max-min and the proportional rate fairness. We propose and compare different routing algorithms, all with three types of fairness definitions. The algorithms are all a tradeoff between network throughput, fairness and computational time.