Hybrid Genetic Bees Algorithm applied to Single Machine Scheduling with Earliness and Tardiness Penalties

This paper presents a hybrid Genetic-Bees Algorithm based optimised solution for the single machine scheduling problem. The enhancement of the Bees Algorithm (BA) is conducted using the Genetic Algorithm's (GA's) operators during the global search stage. The proposed enhancement aims to increase the global search capability of the BA gradually with new additions. Although the BA has very successful implementations on various type of optimisation problems, it has found that the algorithm suffers from weak global search ability which increases the computational complexities on NP-hard type optimisation problems e.g. combinatorial/permutational type optimisation problems. This weakness occurs due to using a simple global random search operation during the search process. To reinforce the global search process in the BA, the proposed enhancement is utilised to increase exploration capability by expanding the number of fittest solutions through the genetical variations of promising solutions. The hybridisation process is realised by including two strategies into the basic BA, named as â\u80\u9creinforced global searchâ\u80\u9d and â\u80\u9cjumping functionâ\u80\u9d strategies. The reinforced global search strategy is the first stage of the hybridisation process and contains the mutation operator of the GA. The second strategy, jumping function strategy, consists of four GA operators as single point crossover, multipoint crossover, mutation and randomisation. To demonstrate the strength of the proposed solution, several experiments were carried out on 280 well-known single machine benchmark instances, and the results are presented by comparing to other well-known heuristic algorithms. According to the experiments, the proposed enhancements provides better capability to basic BA to jump from local minima, and GBA performed better compared to BA in terms of convergence and the quality of results. The convergence time reduced about 60% with about 30% better results for highly constrained jobs

Role of Wide Bandgap Materials in Power Electronics for Smart Grids Applications

At present, the energy transition is leading to the replacement of large thermal power plants by distributed renewable generation and the introduction of different assets. Consequently, a massive deployment of power electronics is expected. A particular case will be the devices destined for urban environments and smart grids. Indeed, such applications have some features that make wide bandgap (WBG) materials particularly relevant. This paper analyzes the most important features expected by future smart applications from which the characteristics that their power semiconductors must perform can be deduced. Following, not only the characteristics and theoretical limits of wide bandgap materials already available on the market (SiC and GaN) have been analyzed, but also those currently being researched as promising future alternatives (Ga2O3, AlN, etc.). Finally, wide bandgap materials are compared under the needs determined by the smart applications, determining the best suited to them. We conclude that, although SiC and GaN are currently the only WBG materials available on the semiconductor portfolio, they may be displaced by others such as Ga2O3 in the near future

Ischemia-reperfusion injury in a rat microvascular skin free flap model: A histological, genetic, and blood flow study.

Ischemia reperfusion injury is associated with tissue damage and inflammation, and is one of the main factors causing flap failure in reconstructive microsurgery. Although ischemia-reperfusion (I/R) injury is a well-studied aspect of flap survival, its biological mechanisms remain to be elucidated. To better understand the biological processes of ischemia reperfusion injury, and to develop further therapeutic strategies, the main objective of this study was to identify the gene expression pattern and histological changes in an I/R injury animal model. Fourteen rats (n = 7/group) were randomly divided into control or ischemia-reperfusion group (8 hours of ischemia). Microsurgical anastomoses were objectively assessed using transit-time-ultrasound technology. Seven days after surgery, flap survival was evaluated and tissue samples were harvested for anatomopathological and gene-expression analyses.The I/R injury reduced the survival of free flaps and histological analyses revealed a subcutaneous edema together with an inflammatory infiltrate. Interestingly, the Arginase 1 expression level as well as the ratio of Arginase 1/Nitric oxide synthase 2 showed a significant increase in the I/R group. In summary, here we describe a well-characterized I/R animal model that may serve to evaluate therapeutic agents under reproducible and controlled conditions. Moreover, this model could be especially useful for the evaluation of arginase inhibitors and different compounds of potential interest in reconstructive microsurgery

Chronic intestinal pseudo-obstruction: a diagnosis to be considered Pseudodestrucción intestinal crónica: un diagnóstico a tener en cuenta

Chronic intestinal pseudoobstruction (CIPO) is a rare entity characterized by recurrent clinical episodes of intestinal obstruction in which no mechanical cause is identified. There are multiple causes for this syndrome but two main groups can be distinguished: a) secondary to a systemic non-gastrointestinal disease; and b) primary or idiopathic originated from alterations in the components of the intestinal wall. The latter forms are the most uncommon and their diagnosis is generally difficult. In the present article, we describe nine patients with CIPO that were diagnosed in our center over the last six years. Four of them were diagnosed with primary or idiopathic form of CIPO and another four were clearly secondary to a systemic disease. The ninth case, which was initially diagnosed as secondary, is probably also a primary form of the disease. The number of patients diagnosed in our center, even thought small, makes us to hypothesize that the prevalence of CIPO is probably greater than is generally believed and that the reasons of its rarity are the incomplete understanding of its physiopathology and the difficulties to achieve a correct diagnosis

Fast minimum float computation in activity networks under interval uncertainty

International audienceThis paper considers the following basic problem in scheduling under uncertainty: given an activity-on-node network where each activity has an uncertain duration represented by an interval, compute the minimum float of each activity over all duration scenarios. For solving this NP-hard problem, Dubois et al. 2005 and Fortin et al. 2010 have recently proposed an algorithm based on path enumeration. In this paper, we establish structural properties of optimal solutions and a new lower bound allowing us to design an efficient branch-and-bound procedure. We also propose two mixed integer programming formulations. The methods are compared experimentally on a large variety of randomly generated problem instances. The results show that the proposed branch-and-bound procedure is very fast and consistently outperforms the MIP formulations and the path enumeration algorithm