Solving diameter‐constrained minimum spanning tree problems by constraint programming

The diameter‐constrained minimum spanning tree problem consists in finding a minimum spanning tree of a given graph, subject to the constraint that the maximum number of edges between any two vertices in the tree is bounded from above by a given constant. This problem typically models network design applications where all vertices communicate with each other at a minimum cost, subject to a given quality requirement. We propose alternative formulations using constraint programming that circumvent weak lower bounds yielded by most mixed‐integer programming formulations. Computational results show that the proposed formulation, combined with an appropriate search procedure, solves larger instances and is faster than other approaches in the literature.     

A biased random‐key genetic algorithm for single‐round divisible load scheduling

A divisible load is an amount W of computational work that can be arbitrarily divided into chunks and distributed among a set P of worker processors to be processed in parallel. Divisible load applications occur in many fields of science and engineering. They can be parallelized in a master‐worker fashion, but they pose several scheduling challenges. The divisible load scheduling problem consists in (a) selecting a subset of active workers, (b) defining the order in which the chunks will be transmitted to each of them, and (c) deciding the amount of load that will be transmitted to each worker , with , so as to minimize the makespan, i.e., the total elapsed time since the master began to send data to the first worker, until the last worker stops its computations. In this work, we propose a biased random‐key genetic algorithm for solving the divisible load scheduling problem. Computational results show that the proposed heuristic outperforms the best heuristic in the literature.     

Discrimination of media moments and media intervals: sticker-based watch-and-comment annotation

In this paper we discuss the problem of how to discriminate moments of interest on videos or live broadcast shows. The primary contribution is a system which allows users to personalize their programs with previously created media stickers??pieces of content that may be temporarily attached to the original video. We present the system??s architecture and implementation, which offer users operators to transparently annotate videos while watching them. We offered a soccer fan the opportunity to add stickers to the video while watching a live match: the user reported both enjoying and being comfortable using the stickers during the match??relevant results even though the experience was not fully representative.     

A GRASP heuristic using path‐relinking and restarts for the Steiner traveling salesman problem

The traveling salesman problem (TSP) is one of the most studied problems in combinatorial optimization. Given a set of nodes and the distances between them, it consists in finding the shortest route that visits each node exactly once and returns to the first. Nevertheless, more flexible and applicable formulations of this problem exist and can be considered. The Steiner TSP (STSP) is a variant of the TSP that assumes that only a given subset of nodes must be visited by the shortest route, eventually visiting some nodes and edges more than once. In this paper, we adapt some classical TSP constructive heuristics and neighborhood structures to the STSP variant. In particular, we propose a reduced 2‐opt neighborhood and we show that it leads to better results in smaller computation times. Computational results with an implementation of a GRASP heuristic using path‐relinking and restarts are reported. In addition, ten large test instances are generated. All instances and their best‐known solutions are made available for download and benchmarking purposes.     

A hybrid genetic algorithm for the phylogeny problem using path-relinking as a progressive crossover strategy

A phylogenetic tree relates taxonomic units using their similarities over a set of characteristics. Given a set of taxonomic units and their characteristics, the phylogeny problem under the parsimony criterion consists in finding a phylogenetic tree with a minimum number of evolutionary steps. We developed a hybrid genetic algorithm for the problem of building a phylogenetic tree minimizing parsimony. The algorithm combines local search with a crossover strategy based on path-relinking, an intensification technique originally used in the context of other metaheuristics such as scatter search and GRASP. Computational experiments on benchmark and randomly generated instances show that the proposed algorithm is very robust and outperforms other heuristics in terms of solution quality and running times.     

A sequential surrogate-based multiobjective optimization method: effect of initial data set

Wireless Networks - Process optimization based on high-fidelity computer simulations or real experimentation is commonly expensive. Therefore, surrogate models are frequently used to reduce the...     

Wind energy assessment and wind farm simulation in Triunfo – Pernambuco,Brazil

This paper presents a wind energy assessment and a wind farm simulation in the city of Triunfo in the state of Pernambuco in the northeast region of Brazil. The wind data were obtained from the SONDA (Sistema de Organização Nacional de Dados Ambientais) project’s meteor station (wind speed, wind direction and temperature) at both heights of 50 m during a period of time of 30 months. The Triunfo wind characterization and wind power potential assessment study shows an average wind speed (V) of 11.27 m/s (predominant Southeast wind direction), an average wind power density (P/A_T) of 1.672 W/m² and Weibull parameters shape (K) and scale (A) respectively equal to 2.0 and 12.7 m/s. Those values demonstrate an important wind potential in this region for future wind farm prospection. The wind farm (TRI) was simulated by using 850 kW wind turbines given a total of 20 MW installed. The simulated results show(s) an AEP (annual energy produced) of 111.4 GWh, a capacity factor (C_f) of 62% and a total of 5.462 h of operation by year (full load hours). The economical simulated results show(s) a Pay-back of 3 years Internal Rate of Return (IRR) of 47% and Net Present Value (NPV) of 85.506 k€ (both in a period of time of 20 years).     

Sensory evaluation of ovine milk yoghurt with inulin addition

The purpose of this study was to elaborate prebiotic yoghurt using ovine milk and different inulin concentrations (0, 2 and 6%). Samples were submitted to laboratory analysis and two sensory tests with 100 consumers. The results of apparent viscosity and firmness determined by instrumental analysis of each yoghurt and control differed significantly. Just‐About‐Right showed consistency as the main attribute that varied in treatments. According to penalty analysis, prebiotic yoghurt containing 6% inulin had minor penalties, which indicates its advantage in the quest to better consumer demands. Hence, this treatment demonstrated better results as well as the many prebiotic benefits associated with an adequate fibre amount.     

Wind resource evaluation in São João do Cariri (SJC) - Paraiba, Brazil

In this study wind resources evaluation and wind energy assessment of the São João do Cariri (SJC) in Paraiba (PB) state situated in Brazilian northeast were analyzed during the period 2006/2009. Wind speed (V, m/s), wind direction and air temperature (T, °C) at 25 m and 50 m were collected from SONDA (Sistema de Organização Nacional de Dados Ambientais) meteorological station (38°N 7°E). The average wind speed and temperature for 25 m and 50 m were found 4.74 m/s, 24.46 °C and 5.31 m/s 24.25 °C respectively. The wind speed predominate direction found were SSE (165°) from both 25 m and 50 m heights. The wind speed distribution curve was obtained using the Weibull probability density function through the WAsP program, the values of Weibull shape (K), scale (A, m/s) and Weibull fit wind speed and power wind density (P, W/m²) were found 2.54, 5.4 m/s, 4.76 m/s and 103 W/m² for 25 m wind height measurements and 2.59, 6.0 m/s, 5.36 m/s and 145 W/m² for 50 m wind height measurements. The cost (€/kWh) from electrical wind energy obtained by wind turbine generation, at 25 m height, was found 0.046 by using 300 kW power rated wind turbine, in the best scenario, with an associate C_f of 14.5%.     

Synbiotic sheep milk ice cream reduces chemically induced mouse colon carcinogenesis

Sheep dairy products containing prebiotic and probiotic ingredients may have health-promoting properties. Thus, this study evaluated the effects of sheep milk ice cream [conventional full-fat (CONV), full-fat enriched with probiotic (PROB, 100 mg % wt/wt of Lacticaseibacillus casei 01), or nonfat synbiotic (SYNB, Lacticaseibacillus casei 01 and inulin, 10% wt/wt)] on carcinogen-induced colonic crypt cytotoxicity and premalignant lesion development. Male Swiss mice received 2 doses of colon carcinogen azoxymethane (AOM, 15 mg/kg of body weight) at wk 3 and 4. Two weeks before and during AOM administrations (4 wk) mice were treated with CONV, PROB, or SYNB by gavage (10 mL/kg). Mice were euthanized at wk 4 or 25 (n = 5 or 10 mice/group, respectively). At wk 4, a significant reduction in micronucleated colonocytes was observed in PROB and SYNB groups, and a significant decrease in both p53 expression and apoptosis indexes in colonic crypts was observed in SYNB group. At wk 25, both PROB and SYNB interventions reduced the mean number of colonic premalignant lesions. However, only SYNB group showed lower incidence and number of high-grade premalignant lesions in the colonic mucosa. These findings indicate that PROB or SYNB sheep milk ice cream, especially SYNB intervention, can reduce chemically induced mouse colon carcinogenesis.