排序方式: 共有37条查询结果,搜索用时 15 毫秒
1.
Fernando Ferraz do Nascimento Andreson Almeida Azevedo Valmaria Rocha da Silva Ferraz 《Journal of applied statistics》2021,48(16):3048
Extreme Value Theory (EVT) aims to study the tails of probability distributions in order to measure and quantify extreme events of maximum and minimum. In river flow data, an extreme level of a river may be related to the level of a neighboring river that flows into it. In this type of data, it is very common for flooding of a location to have been caused by a very large flow from an affluent river that is tens or hundreds of kilometers from this location. In this sense, an interesting approach is to consider a conditional model for the estimation of a multivariate model. Inspired by this idea, we propose a Bayesian model to describe the dependence of exceedance between rivers, where we considered a conditionally independent structure. In this model, the dependence between rivers is captured by modeling the excess marginally of one river as a consequence of linear functions of the other rivers. The results showed that there is a strong and positive connection between excesses in one river caused by the excesses of the other rivers. 相似文献
2.
This article presents the steps of transforming the material and organizational aspects in the work environment, beyond the social order for the proper development of activities in the Household Distribution Center, the Postmen Motorcyclists. The demand was made by managers from the accident records, establishing the need to identify the working conditions of postmen motorcyclists, regarding motorcycle accidents occurring on public roads. Method: Based on the characteristics of the steps required by the methodology, was necessary to realize internal and external observations, with the aim of identifying the dynamics of the accident and the collective dimensions of activity which requires a strategy for monitoring the work on the street. 相似文献
3.
Fernando Ferraz do Nascimento 《Journal of applied statistics》2017,44(13):2410-2426
Abrupt changes often occur for environmental and financial time series. Most often, these changes are due to human intervention. Change point analysis is a statistical tool used to analyze sudden changes in observations along the time series. In this paper, we propose a Bayesian model for extreme values for environmental and economic datasets that present a typical change point behavior. The model proposed in this paper addresses the situation in which more than one change point can occur in a time series. By analyzing maxima, the distribution of each regime is a generalized extreme value distribution. In this model, the change points are unknown and considered parameters to be estimated. Simulations of extremes with two change points showed that the proposed algorithm can recover the true values of the parameters, in addition to detecting the true change points in different configurations. Also, the number of change points was a problem to be considered, and the Bayesian estimation can correctly identify the correct number of change points for each application. Environmental and financial data were analyzed and results showed the importance of considering the change point in the data and revealed that this change of regime brought about an increase in the return levels, increasing the number of floods in cities around the rivers. Stock market levels showed the necessity of a model with three different regimes. 相似文献
4.
Morad Alizadeh Gauss M. Cordeiro Maria do Carmo S. Lima Edwin M. M. Ortega 《Journal of Statistical Computation and Simulation》2017,87(2):367-389
We study a new family of continuous distributions with two extra shape parameters called the Burr generalized family of distributions. We investigate the shapes of the density and hazard rate function. We derive explicit expressions for some of its mathematical quantities. The estimation of the model parameters is performed by maximum likelihood. We prove the flexibility of the new family by means of applications to two real data sets. Furthermore, we propose a new extended regression model based on the logarithm of the Burr generalized distribution. This model can be very useful to the analysis of real data and provide more realistic fits than other special regression models. 相似文献
5.
Aline Canetti Patrícia Póvoa de Mattos Evaldo Muñoz Braz Sylvio Pellico Netto 《Urban Ecosystems》2017,20(5):1057-1068
Urban afforestation improves life quality in urban centers providing social and environmental benefits. Understanding growth of urban trees exposed to air pollution will support planning, managing and expanding urban areas. This approach intends to determine growth patterns of urban trees to support future urban planning. Non-destructive samples were collected from trees of Araucaria angustifolia (Bertol.) Kuntze in Araucaria city, Parana State, Brazil. Growth rings were related to pollutant concentrations and meteorological series. Growth reduction was observed except in the border areas of the city. Trees established during or after the period of industrialization incentives were most affected by air pollution, indicating that immature plants are more vulnerable. Sulphur dioxide and nitric oxide significantly affected growth of smaller trees. Those greater than 60 cm dbh did not demonstrate significant correlation with any identified pollutant. As the trees established before accentuated urbanization were less affected by air pollution, it is reinforced the importance of preserving remaining urban trees. We suggest that planning urban afforestation should precede industries placing. When urban planning is impossible, new planted trees should not be expected to grow as in free pollution areas, but they will still present satisfactory diameter increment, contributing to improve local urban environment. 相似文献
6.
Glaydston Mattos Ribeiro Miguel Fragoso Constantino Luiz Antonio Nogueira Lorena 《Journal of Combinatorial Optimization》2010,20(4):385-398
Earth observation satellites, such as the SPOT 5, take photographs of the earth according to consumers’ demands. Obtaining
a good schedule for the photographs is a combinatorial optimization problem known in the literature as the daily photograph
scheduling problem (DPSP). The DPSP consists of selecting a subset of photographs, from a set of candidates, to different
cameras, maximizing a profit function and satisfying a large number of constraints. Commercial solvers, with standard integer
programming formulations, are not able to solve some DPSP real instances available in the literature. In this paper we present
a strengthened formulation for the DPSP, based on valid inequalities arising in node packing and 3-regular independence system
polyhedra. This formulation was able, with a commercial solver, to solve to optimality all those instances in a short computation
time. 相似文献
7.
Fernando Ferraz do Nascimento Dani Gamerman Hedibert Freitas Lopes 《Statistics and Computing》2012,22(2):661-675
This paper is concerned with extreme value density estimation. The generalized Pareto distribution (GPD) beyond a given threshold
is combined with a nonparametric estimation approach below the threshold. This semiparametric setup is shown to generalize
a few existing approaches and enables density estimation over the complete sample space. Estimation is performed via the Bayesian
paradigm, which helps identify model components. Estimation of all model parameters, including the threshold and higher quantiles,
and prediction for future observations is provided. Simulation studies suggest a few useful guidelines to evaluate the relevance
of the proposed procedures. They also provide empirical evidence about the improvement of the proposed methodology over existing
approaches. Models are then applied to environmental data sets. The paper is concluded with a few directions for future work. 相似文献
8.
Nina Rosa do Amaral Costa Maria Clotilde Rossetti-Ferreira†‡ 《Child & Family Social Work》2009,14(1):58-67
Adoption in Brazil has long been related to practices of not disclosing the child's history and origins, which become a family secret. As a consequence, most couples who apply for adoption prefer newborns. Late adoption is still an uncommon practice and requires a 'family project' which accepts a different family model, new meanings of motherhood and fatherhood, and different ways of building affectionate bonds. It is important to investigate how a man and a woman become parents under those circumstances. This study aimed to follow up the emergence of adoption, motherhood and fatherhood meanings, in the discursive practices involved in the construction of adoptive parenthood in the Brazilian setting. This paper presents important meanings regarding parenthood produced by a couple who adopted two sisters, aged 4 and 5 years. Analysis revealed that to better understand the late adoption process, the meanings that emerge in the discursive practices should be considered. Those meanings pervade and circumscribe the family relationships, influencing how the individuals constitute their roles in the family. It is through the analysis of this dialogical process of construction that it is possible to identify the challenges in late adoption and to unravel the process of constructing affectionate relationships. 相似文献
9.
公元7世纪松赞干布建立吐蕃王朝后,从印度和大唐引入了佛教.吐蕃时期是西藏政治、经济、文化全面发展的黄金时期.相对稳定的政治环境促使吐蕃与周边民族加强了文化交流,同时也开始了佛教经典的翻译.随着唐蕃甥舅关系的进一步稳固发展,吐蕃不仅大力吸收唐朝先进的文明,佛教的引进与佛经翻译也成为唐蕃关系史上重要的一环.本文就吐蕃时期的汉藏佛教界交流和佛经翻译进行了概述和探讨. 相似文献
10.
This article aims to study the importance of the attributes of usability and attractiveness for the semi-public spaces of Shopping Centers considering the elderly users, the psycho-cognitive and bio-physiological changes resulting from the aging process, as well as their expectations of the built space. Through a qualitative study of theoretical review with a multidisciplinary focus in architecture, ergonomics, gerontology, environmental psychology and management, the conditions of the elderly users were identified, and also the attributes related to usability and attractiveness, collected in order to understand and organize their interrelationships, to suggest recommendations about the drafting of Shopping Centers, aiming to generate projects and environments that should promote the efficient and satisfactory use for elderly and may also create a competitive advantage for these enterprises. 相似文献