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Search Results: 1 - 10 of 304338 matches for " Jo?o P. Hespanha "
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Dubins Traveling Salesman Problem with Neighborhoods: A Graph-Based Approach
Jason T. Isaacs,Joo P. Hespanha
Algorithms , 2013, DOI: 10.3390/a6010084
Abstract: We study the problem of finding the minimum-length curvature constrained closed path through a set of regions in the plane. This problem is referred to as the Dubins Traveling Salesperson Problem with Neighborhoods (DTSPN). An algorithm is presented that uses sampling to cast this infinite dimensional combinatorial optimization problem as a Generalized Traveling Salesperson Problem (GTSP) with intersecting node sets. The GTSP is then converted to an Asymmetric Traveling Salesperson Problem (ATSP) through a series of graph transformations, thus allowing the use of existing approximation algorithms. This algorithm is shown to perform no worse than the best existing DTSPN algorithm and is shown to perform significantly better when the regions overlap. We report on the application of this algorithm to route an Unmanned Aerial Vehicle (UAV) equipped with a radio to collect data from sparsely deployed ground sensors in a field demonstration of autonomous detection, localization, and verification of multiple acoustic events.
Modular decomposition and analysis of biological networks
Hari Sivakumar,Stephen R. Proulx,Joo P. Hespanha
Quantitative Biology , 2014,
Abstract: This paper addresses the decomposition of biochemical networks into functional modules that preserve their dynamic properties upon interconnection with other modules, which permits the inference of network behavior from the properties of its constituent modules. The modular decomposition method developed here also has the property that any changes in the parameters of a chemical reaction only affect the dynamics of a single module. To illustrate our results, we define and analyze a few key biological modules that arise in gene regulation, enzymatic networks, and signaling pathways. We also provide a collection of examples that demonstrate how the behavior of a biological network can be deduced from the properties of its constituent modules, based on results from control systems theory.
Corporate greenhouse gas emissions inventories: methods and uses
Gutemberg Hespanha Brasil,Paulo Ant?nio de Souza Junior,Joo Andrade de Carvalho Junior
Sistemas & Gest?o , 2008,
Abstract: Corporate inventories of greenhouse gas emissions, as well as the biomass stock, contain relevant information for the decision makers at the private sector to support their policies related to climate change. A methodology for the calculation of emissions from processes and services is presented. This methodology includes the expressions of uncertainties associated to the calculation of greenhouse gas emissions. The importance of the knowledge of these uncertainties is also discussed.
Inventários corporativos de gases de efeito estufa: métodos e usos
Gutemberg Hespanha Brasil,Paulo Ant?nio De Souza Junior,Joo Andrade De Carvalho Junior
Sistemas & Gest?o , 2009,
Abstract: Inventários corporativos de emiss es de gases causadores do efeito estufa, bem como de estoques de carbono em biomassa, contém informa es importantes para os tomadores de decis o de grandes empresas no apoio à formula o de políticas em rela o às mudan as climáticas. Apresenta-se aqui uma metodologia de cálculo das emiss es de processos e servi os, incluindo também estimativas de incertezas associadas. Discute-se a importancia para a empresa no conhecimento dessas incertezas.
Error Scaling Laws for Linear Optimal Estimation from Relative Measurements
Prabir Barooah,Joao P. Hespanha
Mathematics , 2009,
Abstract: We study the problem of estimating vector-valued variables from noisy "relative" measurements. This problem arises in several sensor network applications. The measurement model can be expressed in terms of a graph, whose nodes correspond to the variables and edges to noisy measurements of the difference between two variables. We take an arbitrary variable as the reference and consider the optimal (minimum variance) linear unbiased estimate of the remaining variables. We investigate how the error in the optimal linear unbiased estimate of a node variable grows with the distance of the node to the reference node. We establish a classification of graphs, namely, dense or sparse in Rd,1<= d <=3, that determines how the linear unbiased optimal estimation error of a node grows with its distance from the reference node. In particular, if a graph is dense in 1,2, or 3D, then a node variable's estimation error is upper bounded by a linear, logarithmic, or bounded function of distance from the reference, respectively. Corresponding lower bounds are obtained if the graph is sparse in 1, 2 and 3D. Our results also show that naive measures of graph density, such as node degree, are inadequate predictors of the estimation error. Being true for the optimal linear unbiased estimate, these scaling laws determine algorithm-independent limits on the estimation accuracy achievable in large graphs.
ética e violência na teoria das rela??es internacionais: uma reflex?o a partir do 11 de Setembro
Nogueira, Joo P;
Contexto Internacional , 2003, DOI: 10.1590/S0102-85292003000100003
Abstract: the attacks of september 2001 were the most significant instance of the use of force by a non-state agent against a sovereign state in the history of the modern international system. an event of such significance should, in itself, stimulate further discussion about the standing of states in world politics, as wells as on the ethical foundations of today's international system. unfortunately, most debates have focused on the us response to the attacks and their consequences, circumscribed by the conventional standards of the logic of anarchy. condemnations of the attacks have often reproduced the duality between ethical considerations and political analysis. this work raises some questions about the use of force in world politics in an attempt to contribute to a discussion about the ethical basis of the economy of violence today.
Ecological analogies between estuarine bottom trawl fish assemblages from Patos Lagoon, Rio Grande do Sul, Brazil and York River, Virginia, USA
Vieira, Joo P.;
Revista Brasileira de Zoologia , 2006, DOI: 10.1590/S0101-81752006000100017
Abstract: the structure of estuarine fish assemblages at temperate latitudes in patos lagoon (32o05's, 52o04'w), rio grande do sul, brazil and york river (37o17'n, 76o33'w), virginia, usa was compared using mid and late 1970's data from bottom trawl collection to investigate whether geographically isolated fish assemblages have similar ecological structure given similar latitudinal positions on the warmtemperate southwestern and northwestern atlantic regions, respectively. since estuarine species often exhibit an ontogenetic shift in habitat requirements or preferences we examined capture per unity of effort by size class (cpue-sc) and split species into "size ecological taxa" (set) for analysis. the use of cpue-sc also allowed the abundance of a set to be computed by summing the mean cpue of each size class within that set and use this information to follows set's temporal and or spatial abundance. a total of 65 and 63 species was collected during a year of bottom trawling in the patos lagoon and york river estuaries, respectively. in both localities the strongest modal size class was < 80 mm tl, and several abundant species were smaller than 100 mm tl. the size between 80 and 100 tl effectively separated several species into discrete set's in both systems. those set's could have different ecological preferences, temporal and spatial distributions and so identified as different "ecological taxa". in warm months, when predation by large fish is most likely, the abundance of fish between 80 and 100 mm tl in "bottom trawl" demersal fish assemblages was low in both systems. only the sea catfishes, in patos lagoon, protected by strong dorsal and pectoral spines, and the hogchoker, in the york river, protected by burrowing in the bottom substrate, peak in abundance at this size class. the seasonal pattern of estuarine use was similar between localities and did not differ from other warm-temperate estuarine fish assemblages.
Uso da Propriedade da Aditividade de Componentes de Biomassa Individual de Quercus pyrenaica Willd. com Recurso a um Sistema de Equa??es N?o-Linear
Carvalho,Joo P.;
Silva Lusitana , 2003,
Abstract: the biomass as a measure of the primary yield of forest ecosystems has had an increased interest, mainly with tree species in which their crown is an usable component. in total tree biomass estimations, it is important to consider the property of addition of the stem and crown biomass components. in this work, two procedures are compared that apply the summation factor between the biomass components of quercus pyrenaica willd. trees, as applied to a specific case. results show that the use of a process of simultaneous estimates of a system of equations, which impose restrictions in the estimate of parameters and considers the existence of a simultaneous correlation between residuals, results in the derivation of more efficient parameters giving more consistent intervals in the prediction of biomass estimates.
Water Microbiology. Bacterial Pathogens and Water
Joo P. S. Cabral
International Journal of Environmental Research and Public Health , 2010, DOI: 10.3390/ijerph7103657
Abstract: Water is essential to life, but many people do not have access to clean and safe drinking water and many die of waterborne bacterial infections. In this review a general characterization of the most important bacterial diseases transmitted through water—cholera, typhoid fever and bacillary dysentery—is presented, focusing on the biology and ecology of the causal agents and on the diseases’ characteristics and their life cycles in the environment. The importance of pathogenic Escherichia coli strains and emerging pathogens in drinking water-transmitted diseases is also briefly discussed. Microbiological water analysis is mainly based on the concept of fecal indicator bacteria. The main bacteria present in human and animal feces (focusing on their behavior in their hosts and in the environment) and the most important fecal indicator bacteria are presented and discussed (focusing on the advantages and limitations of their use as markers). Important sources of bacterial fecal pollution of environmental waters are also briefly indicated. In the last topic it is discussed which indicators of fecal pollution should be used in current drinking water microbiological analysis. It was concluded that safe drinking water for all is one of the major challenges of the 21st century and that microbiological control of drinking water should be the norm everywhere. Routine basic microbiological analysis of drinking water should be carried out by assaying the presence of Escherichia coli by culture methods. Whenever financial resources are available, fecal coliform determinations should be complemented with the quantification of enterococci. More studies are needed in order to check if ammonia is reliable for a preliminary screening for emergency fecal pollution outbreaks. Financial resources should be devoted to a better understanding of the ecology and behavior of human and animal fecal bacteria in environmental waters.
Ecological aspects of the vectorial control of Chagas' disease in Brazil
Dias, Joo Carlos P.;
Cadernos de Saúde Pública , 1994, DOI: 10.1590/S0102-311X1994000800013
Abstract: the feasibility and most important ecological aspects of vectorial chagas' disease control are discussed. the spread and maintenance of this disease involve multiple ecological and sociopolitical factors that must be taken into account when control programs are planned, executed and evaluated. in spite of its complexity, chagas disease can be controlled using methods that target specific mechanisms of transmission, the most important being vectorial and transfusional. major ecological problems in chagas' disease control do not exist, even in the case of the chemical control of triatomine vectors. the main challenges for the brazilian control program at this moment are: its maintenance as a political priority; the threat of peridomestic vectors; and the consolidation of permanent horizontal and participative epidemiological surveillance systems against the vector.
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