992 resultados para Multiobjective (MO) optimization


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Monitoring and management of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) is a standard of care after traumatic brain injury (TBI). However, the pathophysiology of so-called secondary brain injury, i.e., the cascade of potentially deleterious events that occur in the early phase following initial cerebral insult-after TBI, is complex, involving a subtle interplay between cerebral blood flow (CBF), oxygen delivery and utilization, and supply of main cerebral energy substrates (glucose) to the injured brain. Regulation of this interplay depends on the type of injury and may vary individually and over time. In this setting, patient management can be a challenging task, where standard ICP/CPP monitoring may become insufficient to prevent secondary brain injury. Growing clinical evidence demonstrates that so-called multimodal brain monitoring, including brain tissue oxygen (PbtO2), cerebral microdialysis and transcranial Doppler among others, might help to optimize CBF and the delivery of oxygen/energy substrate at the bedside, thereby improving the management of secondary brain injury. Looking beyond ICP and CPP, and applying a multimodal therapeutic approach for the optimization of CBF, oxygen delivery, and brain energy supply may eventually improve overall care of patients with head injury. This review summarizes some of the important pathophysiological determinants of secondary cerebral damage after TBI and discusses novel approaches to optimize CBF and provide adequate oxygen and energy supply to the injured brain using multimodal brain monitoring.

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We address the performance optimization problem in a single-stationmulticlass queueing network with changeover times by means of theachievable region approach. This approach seeks to obtainperformance bounds and scheduling policies from the solution of amathematical program over a relaxation of the system's performanceregion. Relaxed formulations (including linear, convex, nonconvexand positive semidefinite constraints) of this region are developedby formulating equilibrium relations satisfied by the system, withthe help of Palm calculus. Our contributions include: (1) newconstraints formulating equilibrium relations on server dynamics;(2) a flow conservation interpretation of the constraintspreviously derived by the potential function method; (3) newpositive semidefinite constraints; (4) new work decomposition lawsfor single-station multiclass queueing networks, which yield newconvex constraints; (5) a unified buffer occupancy method ofperformance analysis obtained from the constraints; (6) heuristicscheduling policies from the solution of the relaxations.

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We address the problem of scheduling a multi-station multiclassqueueing network (MQNET) with server changeover times to minimizesteady-state mean job holding costs. We present new lower boundson the best achievable cost that emerge as the values ofmathematical programming problems (linear, semidefinite, andconvex) over relaxed formulations of the system's achievableperformance region. The constraints on achievable performancedefining these formulations are obtained by formulatingsystem's equilibrium relations. Our contributions include: (1) aflow conservation interpretation and closed formulae for theconstraints previously derived by the potential function method;(2) new work decomposition laws for MQNETs; (3) new constraints(linear, convex, and semidefinite) on the performance region offirst and second moments of queue lengths for MQNETs; (4) a fastbound for a MQNET with N customer classes computed in N steps; (5)two heuristic scheduling policies: a priority-index policy, anda policy extracted from the solution of a linear programmingrelaxation.

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O país está a atravessar uma fase singular no setor da construção civil, particularmente no segmento das edificações. Entretanto, como consequência da falta de investimentos na capacitação de mão-de-obra, a construção civil sofre da escassez de profissionais especializados em quantidade e qualidade exigidas pelo setor. Na realidade a capacitação de mão-de-obra vem se mostrando cada vez mais indispensável para as empresas que disputam um espaço no mercado. No entanto houve um crescimento no volume de obras no país, porém a quantidade de profissionais capacitados e qualificados, para realizarem as diversas atividades das células de produção de uma obra, não apresentaram o mesmo crescimento. É neste contexto que se insere o presente trabalho, cujo foco é a capacitação profissional a nível operacional, tendo como objetivo propor diretrizes nessa área.

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La ruta sintètica del bis(2-((difenilfosfino)metil)fenil)sulfà, Ph2PCH2-(C6H4)S(C6H4)-CH2PPh2 , DPTMephos, involucra 5 reaccions en 4 etapes ben diferenciades. Es per aquest motiu que es fa necessària una optimització de la ruta sintètica per assolir rendiments més elevats. La primera reacció parteix del sulfur de difenil i involucra la formació d’un complex litiat per acabar realitzant una carbonilació amb N,N-DMF per obtindre un dialdehid. El següent pas de la ruta passa per la reducció del producte al diol corresponent. Tot seguit ja es por preparar el substrat mitjanjant una bromació per a que en l’última etapa, s’acobli a l’estructura el grup difenilfosfino. Tant mateix s’han sintetitzat els isòmers de la DPTMephos amb [W(CO)6] i [Mo(CO)6], observant-se la formació tant dels complexos meridionals com facials i la seva interconversió. Tot seguit s’ha desenvolupat la sulfuració de la DPTMephos per obtindre els lligands tant mono com di sulfurats. També s’ha realitzat un estudi de l’espectre de RMN 31P{1H} del complex fac-[Mo(CO)3(DPTMephos)] a temperatura variable per determinar el senyal de cada fòsfor no equivalent a 200K. S’ha realitzat un estudi de forma qualitativa de les conformacions que adopta l’anell quelat de 6 baules en les conformacions tant meridional com facial d’un complex.

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In a previous paper a novel Generalized Multiobjective Multitree model (GMM-model) was proposed. This model considers for the first time multitree-multicast load balancing with splitting in a multiobjective context, whose mathematical solution is a whole Pareto optimal set that can include several results than it has been possible to find in the publications surveyed. To solve the GMM-model, in this paper a multi-objective evolutionary algorithm (MOEA) inspired by the Strength Pareto Evolutionary Algorithm (SPEA) is proposed. Experimental results considering up to 11 different objectives are presented for the well-known NSF network, with two simultaneous data flows

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Crushed seeds of the Moringa oleifera tree have been used traditionally as natural flocculants to clarify drinking water. We previously showed that one of the seed peptides mediates both the sedimentation of suspended particles such as bacterial cells and a direct bactericidal activity, raising the possibility that the two activities might be related. In this study, the conformational modeling of the peptide was coupled to a functional analysis of synthetic derivatives. This indicated that partly overlapping structural determinants mediate the sedimentation and antibacterial activities. Sedimentation requires a positively charged, glutamine-rich portion of the peptide that aggregates bacterial cells. The bactericidal activity was localized to a sequence prone to form a helix-loop-helix structural motif. Amino acid substitution showed that the bactericidal activity requires hydrophobic proline residues within the protruding loop. Vital dye staining indicated that treatment with peptides containing this motif results in bacterial membrane damage. Assembly of multiple copies of this structural motif into a branched peptide enhanced antibacterial activity, since low concentrations effectively kill bacteria such as Pseudomonas aeruginosa and Streptococcus pyogenes without displaying a toxic effect on human red blood cells. This study thus identifies a synthetic peptide with potent antibacterial activity against specific human pathogens. It also suggests partly distinct molecular mechanisms for each activity. Sedimentation may result from coupled flocculation and coagulation effects, while the bactericidal activity would require bacterial membrane destabilization by a hydrophobic loop.

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Foi avaliado o efeito da omissão de N, Ni, Mo, Co e S sobre os teores de N e S em feijoeiros (Phaseolus vulgaris ) inoculados e não inoculados com Rhizobium, em casa de vegetação. O experimento foi realizado em um esquema fatorial com dois tipos de solo (Neossolo Flúvico), dois níveis de inoculação (com e sem), combinados com seis adubações: (a) Completo (N, P, K, Ni, Mo, Co e S); (b) sem N; (c) sem Ni; (d) sem Co; (e) sem Mo; (f) sem S. O delineamento experimental foi inteiramente casualizado com três repetições. Foram fornecidos 126 mg kg-1 de N (parcelados no plantio, aos 10 e 25 dias da emergência - DAE), 248 mg kg-1 de P, 117 de K e 48 de S, aplicados no solo, e 10, 250 e 10 mg L-1 de Ni, Mo e Co, respectivamente, aplicados via foliar aos nove DAE. A colheita foi efetuada aos 35 DAE, separando-se a folha indicadora das demais. A adubação nitrogenada aumentou o crescimento das plantas, indicando serem os solos deficientes em N, bem como reduziu os teores foliares de N e S. A omissão dos demais nutrientes não alterou o crescimento das plantas nem o teor de N foliar, mas a omissão de S reduziu, como esperado, o teor de S foliar.

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Selostus: Ó-lactalbumiinin ja ¿̐ư-lactoglobuliinin sentrifugointierotuksen optimointi

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A systematic method to improve the quality (Q) factor of RF integrated inductors is presented in this paper. The proposed method is based on the layout optimization to minimize the series resistance of the inductor coil, taking into account both ohmic losses, due to conduction currents, and magnetically induced losses, due to eddy currents. The technique is particularly useful when applied to inductors in which the fabrication process includes integration substrate removal. However, it is also applicable to inductors on low-loss substrates. The method optimizes the width of the metal strip for each turn of the inductor coil, leading to a variable strip-width layout. The optimization procedure has been successfully applied to the design of square spiral inductors in a silicon-based multichip-module technology, complemented with silicon micromachining postprocessing. The obtained experimental results corroborate the validity of the proposed method. A Q factor of about 17 have been obtained for a 35-nH inductor at 1.5 GHz, with Q values higher than 40 predicted for a 20-nH inductor working at 3.5 GHz. The latter is up to a 60% better than the best results for a single strip-width inductor working at the same frequency.

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Nickel, although essential to plants, may be toxic to plants and animals. It is mainly assimilated by food ingestion. However, information about the average levels of elements (including Ni) in edible vegetables from different regions is still scarce in Brazil. The objectives of this study were to: (a) evaluate and optimize a method for preparation of vegetable tissue samples for Ni determination; (b) optimize the analytical procedures for determination by Flame Atomic Absorption Spectrometry (FAAS) and by Electrothermal Atomic Absorption (ETAAS) in vegetable samples and (c) determine the Ni concentration in vegetables consumed in the cities of Lorena and Taubaté in the Vale do Paraíba, State of São Paulo, Brazil. By means of the analytical technique for determination by ETAAS or FAAS, the results were validated by the test of analyte addition and recovery. The most viable method tested for quantification of this element was HClO4-HNO3 wet digestion. All samples but carrot tissue collected in Lorena contained Ni levels above the permitted by the Brazilian Ministry of Health. The most disturbing results, requiring more detailed studies, were the Ni concentrations measured in carrot samples from Taubaté, where levels were five times higher than permitted by Brazilian regulations.