927 resultados para Elementary shortest path with resource constraints
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Agronomia (Energia na Agricultura) - FCA
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The aim of this paper is to provide an overview of the gender and social disparities existing in the agricultural and rural sector in Caribbean economies. In this context, agricultural transformation as occasioned by the dismantling of preferential trading arrangements is analysed to identify the most relevant gender discriminatory measures in the current agricultural development policy and programmes. The analysis seeks to provide the basis for enhancing understanding among policy makers, planners and rural development practitioners of the gender and social dimension involved in the formulation of agricultural policy and more specifically in relation to the new policy and institutional arrangements for agriculture in the region. The paper also provides insights regarding what changes should take place to create an enabling environment for more gender-based approaches to policy-making and strategic planning in agricultural development and trade in the Caribbean. The methodology centred on the review of secondary sources that provide references on the new challenges, opportunities and constraints faced by the agricultural sector, in particular small farmers, in the context of globalization and agriculture transformation. Much of the literature for this assignment was obtained from FAO Headquarters in Rome and the FAO Subregional Office in Barbados, as well as the OECS Secretariat in St. Lucia. In the process of the review exercise, due consideration was given to changes in agricultural production patterns, resources allocation and rural livelihoods. Efforts to examine the most relevant policy measures and mechanisms in-place in support to agricultural development in the region were constrained, in the main, by the absence of gender disaggregated data. Documentation as regards the situation of women and men in relation to agricultural labour, rural income and food security situation in regions were limited. The use of the internet served to bridge the communication gap between countries and institutions. The preliminary draft of the paper was presented and discussed at the FAO/ECLAC/UNIFEM regional workshop on mainstreaming gender analysis in agriculture and trade policies, for Caribbean countries, in November 2003. The second draft of the paper was informed by comments from the workshop and additional information acquired through field visits to Barbados, St. Kitts and St. Vincent in March 2004. The three day visits to each of these three countries entailed a review/appreciation of the resource, constraints and institutional capacities for gender mainstreaming within the agricultural sector at the national level. This included visits to some of the major agricultural projects and interviews with farmers (where feasible) in respect of their perspective of the current situation of the agricultural sector and the viability of their farm enterprises. As well, meetings were held with relevant/available officials within the respective ministries of agriculture to discern the gender consideration as regards agricultural policy and planning at the country level. The internet was invaluable to the task of sourcing supplementary information to satisfy the aim of the paper; in respect of the identification of concrete policy measures and actions to formulate and develop more gender/social-responsive agricultural development policies. The final revision, though thwart with resource and communication constraints, was ultimately completed in compliance with the structure and approach proposed in the terms of references for this FAO/ECLAC assignment.
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In this paper, we propose a hybrid methodology based on Graph-Coloring and Genetic Algorithm (GA) to solve the Wavelength Assignment (WA) problem in optical networks, impaired by physical layer effects. Our proposal was developed for a static scenario where the physical topology and traffic matrix are known a priori. First, we used fixed shortest-path routing to attend demand requests over the physical topology and the graph-coloring algorithm to minimize the number of necessary wavelengths. Then, we applied the genetic algorithm to solve WA. The GA finds the wavelength activation order on the wavelengths grid with the aim of reducing the Cross-Phase Modulation (XPM) effect; the variance due to the XPM was used as a function of fitness to evaluate the feasibility of the selected WA solution. Its performance is compared with the First-Fit algorithm in two different scenarios, and has shown a reduction in blocking probability up to 37.14% when considered both XPM and residual dispersion effects and up to 71.42% when only considered XPM effect. Moreover, it was possible to reduce by 57.14% the number of wavelengths.
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This paper considers the multi-plant lot sizing problem. Each item can be produced in any plant and it is possible to meet the demand of a particular plant with production from one (or several) other plants, in this case, incurs a transfer cost. The objective is todevelop strong formulations for this problem. Reformulations that based on the shortest path problem and facility location problem are investigated. Finally, some computational results are presented comparing all the proposed formulations.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Engenharia de Produção - FEB
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Teaching resources involve different elements used to support the organization of teaching and learning. Among these are the comic books, involving visual aspects, both cognitive and creative, that provide an alternative way to complement the lectures. The aim of this study was to develop and evaluate a comic book entitled “Human Body”, focusing on the circulatory, digestive, nervous and respiratory systems, to provide an alternative resource for the teaching of the content in the initial years. The material was evaluated with students of the 5th year of elementary education at a public school in the state of São Paulo, through the use of questionnaires. The comic book proved to be valid as a complementary teaching resource for learning in students, enabling reflection on the relevance of the development and use of comics to science education in the initial years.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Lightpath scheduling is an important capability in next-generation wavelength-division multiplexing (WDM) optical networks to reserve resources in advance for a specified time period while provisioning end-to-end lightpaths. In this study, we propose an approach to support dynamic lightpath scheduling in such networks. To minimize blocking probability in a network that accommodates dynamic scheduled lightpath demands (DSLDs), resource allocation should be optimized in a dynamic manner. However, for the network users who desire deterministic services, resources must be reserved in advance and guaranteed for future use. These two objectives may be mutually incompatible. Therefore, we propose a two-phase dynamic lightpath scheduling approach to tackle this issue. The first phase is the deterministic lightpath scheduling phase. When a lightpath request arrives, the network control plane schedules a path with guaranteed resources so that the user can get a quick response with the deterministic lightpath schedule. The second phase is the lightpath re-optimization phase, in which the network control plane re-provisions some already scheduled lightpaths. Experimental results show that our proposed two-phase dynamic lightpath scheduling approach can greatly reduce WDM network blocking.
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Sparse traffic grooming is a practical problem to be addressed in heterogeneous multi-vendor optical WDM networks where only some of the optical cross-connects (OXCs) have grooming capabilities. Such a network is called as a sparse grooming network. The sparse grooming problem under dynamic traffic in optical WDM mesh networks is a relatively unexplored problem. In this work, we propose the maximize-lightpath-sharing multi-hop (MLS-MH) grooming algorithm to support dynamic traffic grooming in sparse grooming networks. We also present an analytical model to evaluate the blocking performance of the MLS-MH algorithm. Simulation results show that MLSMH outperforms an existing grooming algorithm, the shortest path single-hop (SPSH) algorithm. The numerical results from analysis show that it matches closely with the simulation. The effect of the number of grooming nodes in the network on the blocking performance is also analyzed.
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The use of statistical methods to analyze large databases of text has been useful in unveiling patterns of human behavior and establishing historical links between cultures and languages. In this study, we identified literary movements by treating books published from 1590 to 1922 as complex networks, whose metrics were analyzed with multivariate techniques to generate six clusters of books. The latter correspond to time periods coinciding with relevant literary movements over the last five centuries. The most important factor contributing to the distinctions between different literary styles was the average shortest path length, in particular the asymmetry of its distribution. Furthermore, over time there has emerged a trend toward larger average shortest path lengths, which is correlated with increased syntactic complexity, and a more uniform use of the words reflected in a smaller power-law coefficient for the distribution of word frequency. Changes in literary style were also found to be driven by opposition to earlier writing styles, as revealed by the analysis performed with geometrical concepts. The approaches adopted here are generic and may be extended to analyze a number of features of languages and cultures.
The boundedness of penalty parameters in an augmented Lagrangian method with constrained subproblems
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Augmented Lagrangian methods are effective tools for solving large-scale nonlinear programming problems. At each outer iteration, a minimization subproblem with simple constraints, whose objective function depends on updated Lagrange multipliers and penalty parameters, is approximately solved. When the penalty parameter becomes very large, solving the subproblem becomes difficult; therefore, the effectiveness of this approach is associated with the boundedness of the penalty parameters. In this paper, it is proved that under more natural assumptions than the ones employed until now, penalty parameters are bounded. For proving the new boundedness result, the original algorithm has been slightly modified. Numerical consequences of the modifications are discussed and computational experiments are presented.
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Abstract Background The structure of regulatory networks remains an open question in our understanding of complex biological systems. Interactions during complete viral life cycles present unique opportunities to understand how host-parasite network take shape and behave. The Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) is a large double-stranded DNA virus, whose genome may encode for 152 open reading frames (ORFs). Here we present the analysis of the ordered cascade of the AgMNPV gene expression. Results We observed an earlier onset of the expression than previously reported for other baculoviruses, especially for genes involved in DNA replication. Most ORFs were expressed at higher levels in a more permissive host cell line. Genes with more than one copy in the genome had distinct expression profiles, which could indicate the acquisition of new functionalities. The transcription gene regulatory network (GRN) for 149 ORFs had a modular topology comprising five communities of highly interconnected nodes that separated key genes that are functionally related on different communities, possibly maximizing redundancy and GRN robustness by compartmentalization of important functions. Core conserved functions showed expression synchronicity, distinct GRN features and significantly less genetic diversity, consistent with evolutionary constraints imposed in key elements of biological systems. This reduced genetic diversity also had a positive correlation with the importance of the gene in our estimated GRN, supporting a relationship between phylogenetic data of baculovirus genes and network features inferred from expression data. We also observed that gene arrangement in overlapping transcripts was conserved among related baculoviruses, suggesting a principle of genome organization. Conclusions Albeit with a reduced number of nodes (149), the AgMNPV GRN had a topology and key characteristics similar to those observed in complex cellular organisms, which indicates that modularity may be a general feature of biological gene regulatory networks.