A semi-analytical solution for vibration of rectangular plates with abrupt thickness variation

A semi-analytical analysis of free vibration of plates with cross-sectional discontinuities due to abrupt changes in thickness is presented. A basic square element divided into suitable subdomains dependent upon the positions of these abrupt changes is used as the basic building element, Admissible functions that satisfy the essential or geometric boundary conditions are used to define the transverse deflection of each subdomain. Continuities in the displacement, slope, moment and higher derivatives between adjacent subdomains are enforced at the interconnecting edges. The resulting global energy functional from the proper assembly of the coupled strain and kinetic energy contributions of each subdomain is then minimized via the Ritz procedure to extract the frequencies and mode shapes. Contour plots of a range of new mode shapes are presented for the enhancement of understanding the dynamic behavior of this class of plates, (C) 2001 Elsevier Science Ltd, All rights reserved.

Engineering closure of an open pit gold operation in a semi-arid climate

Along with material characteristics and geometry, the climate in which a mine is located can have a dramatic effect on the appropriate options for rehabilitation. The paper outlines the setting, mining, milling and waste disposal at Kidston Gold Mine's open pit operations in the semi-arid climate of North Queensland, Australia, before focusing on the engineering aspects of the rehabilitation of Kidston. The mine took a holistic and proactive approach to rehabilitation, and was prepared to demonstrate a number of innovative approaches, which are described in the paper. Engineering issues that had to be addressed included the geotechnical stability and deformation of waste rock dumps, including a 240 m high in-pit dump: the construction and performance monitoring of a “store and release” cover over potentially acid forming mineralised waste rock; erosion from the side slopes of the waste rock dumps; the in-pit co-disposal of waste rock and thickened tailings; the geotechnical stability of the tailings dam wall; the potential for erosion of bare tailings; the water balance of the tailings dam; direct revegetation of the tailings; and the pit hydrology. The rehabilitation of the mine represents an important benchmark in mine site rehabilitation best practice, from which lessons applicable worldwide can be shared.

Ontogenetic changes of swimming kinematics in a semi-aquatic reptile (Crocodylus porosus)

Semi-aquatic animals represent a transitional locomotor condition characterised by the possession of morphological features that allow locomotion both in water and on land. Most ecologically important behaviours of crocodilians occur in the water, raising the question of whether their 'terrestrial construction' constrains aquatic locomotion. Moreover, the demands for aquatic locomotion change with life-history stage. It was the aim of this research to determine the kinematic characteristics and efficiency of aquatic locomotion in different-sized crocodiles (Crocodylus porosus). Aquatic propulsion was achieved primarily by tail undulations, and the use of limbs during swimming was observed only in very small animals or at low swimming velocities in larger animals. Over the range of swimming speeds we examined, tail beat amplitude did not change with increasing velocity, but amplitude increased significantly with body length. However, amplitude expressed relative to body length decreased with increasing body length. Tail beat frequency increased with swimming velocity but there were no differences in frequency between different-sized animals. Mechanical power generated during swimming and thrust increased non-linearly with swimming velocity, but disproportionally so that kinematic efficiency decreased with increasing swimming velocity. The importance of unsteady forces, expressed as the reduced frequency, increased with increasing swimming velocity. Amplitude is the main determinant of body-size-related increases in swimming velocity but, compared with aquatic mammals and fish, crocodiles are slow swimmers probably because of constraints imposed by muscle performance and unsteady forces opposing forward movement. Nonetheless, the kinematic efficiency of aquatic locomotion in crocodiles is comparable to that of fully aquatic mammals, and it is considerably greater than that of semi-aquatic mammals.

An EM-based Semi-Parametric Mixture Model Approach to the Regression Analysis of Competing-Risks Data

We consider a mixture model approach to the regression analysis of competing-risks data. Attention is focused on inference concerning the effects of factors on both the probability of occurrence and the hazard rate conditional on each of the failure types. These two quantities are specified in the mixture model using the logistic model and the proportional hazards model, respectively. We propose a semi-parametric mixture method to estimate the logistic and regression coefficients jointly, whereby the component-baseline hazard functions are completely unspecified. Estimation is based on maximum likelihood on the basis of the full likelihood, implemented via an expectation-conditional maximization (ECM) algorithm. Simulation studies are performed to compare the performance of the proposed semi-parametric method with a fully parametric mixture approach. The results show that when the component-baseline hazard is monotonic increasing, the semi-parametric and fully parametric mixture approaches are comparable for mildly and moderately censored samples. When the component-baseline hazard is not monotonic increasing, the semi-parametric method consistently provides less biased estimates than a fully parametric approach and is comparable in efficiency in the estimation of the parameters for all levels of censoring. The methods are illustrated using a real data set of prostate cancer patients treated with different dosages of the drug diethylstilbestrol. Copyright (C) 2003 John Wiley Sons, Ltd.

Speleothem U-series dating of semi-synchronous climate oscillations during the last deglaciation

Evidence for nearly synchronous climate oscillations during the last deglaciation has been found throughout the Northern Hemisphere but few records are based on independent time scales of calendar years. We present a rare uranium-series dated oxygen-carbon isotope record for a speleothem from Tangshan Cave, China, which demonstrates that abrupt deglacial climatic oscillations from 16 800 to 10 500 yr BP are semi-synchronous with those found in Greenland ice core records. Relatively rapid shifts in speleothem oxygen isotope ratios demonstrate that the intensity of the East Asian monsoon switched in parallel with the abrupt transitions separating the Bolling-Allerod, Younger Dryas, and pre-Boreal climatic reversals. However, the dated isotopic transitions appear to have lasted longer. Our results demonstrate the dominant role of atmospheric teleconnections in the rapid propagation of deglacial climatic signals on a hemispheric scale, and highlight the importance of U-series dated speleothems in the timing and characterization of abrupt climate change. (C) 2003 Elsevier B.V. All rights reserved.

Boletim eletr??nico de bibliografias especializadas: meio ambiente e sustentabilidade

A 3a edi????o de 2013 do Boletim Eletr??nico de Bibliografias Especializadas re??ne publica????es do acervo da Biblioteca Graciliano Ramos com a tem??tica Meio Ambiente e Sustentabilidade, por ocasi??o do Dia Mundial do Meio Ambiente, comemorado anualmente em 5 de junho. A data busca chamar a aten????o e a a????o pol??tica de povos e pa??ses a fim de aumentar a conscientiza????o e a preserva????o ambiental. A divulga????o das publica????es a seguir - que tratam de ecologia, saneamento b??sico, polui????o, desenvolvimento sustent??vel, economia verde, gest??o ambiental, entre outros - tem como expectativa apoiar a forma????o e a capacita????o de servidores p??blicos, bem como a aplica????o desse conhecimento em pol??ticas p??blicas, em benef??cio da popula????o

Dimensional X: a dificuldade na obten????o da informa????o em meio a problemas na gest??o de pessoas

Ant??nio foi convidado para assumir um cargo em que deveria gerenciar os sistemas de informa????o de um grande minist??rio. Com a miss??o inicial de fornecer uma informa????o sobre a for??a de trabalho, percebeu que havia problemas que iam muito al??m da simples utiliza????o desses sistemas, como a pol??tica de capacita????o de pessoal, a rotatividade de servidores, a falta de integra????o entre as ??reas e outros problemas na ??rea de gest??o de pessoas

Educa????o sanit??ria em agrot??xicos, sa??de humana e meio ambiente

Agricultores e consumidores v??m sofrendo os efeitos negativos do uso incorreto de agrot??xicos. Como s??o poucos os recursos dispon??veis para capacitar agricultores e existe dificuldade de reuni-los no hor??rio de expediente normal para capacit??-los, foi usada uma estrat??gia que utiliza professores e estudantes universit??rios como multiplicadores. Estes capacitam alunos da 7a s??rie em diante, que t??m a tarefa de repassar os conhecimentos adquiridos para pessoas de sua conviv??ncia que trabalham na agricultura. Os resultados dessa capacita????o em cadeia t??m sido bons, em termos de aprendizagem e de mudan??a positiva de comportamentos dos agricultores. O conhecimento est?? chegando ??s camadas mais pobres da popula????o com bom n??vel de qualidade. Diminuiu o n??mero de pessoas intoxicadas, os jovens est??o desenvolvendo o senso de cidadania e de solidariedade, os custos s??o muito baixos, o ambiente est?? menos polu??do com embalagens vazias de agrot??xicos

Centro de pesquisa do HCPA: inovando a gest??o da pesquisa, por meio de laborat??rios compartilhados

O Hospital de Cl??nicas de Porto Alegre (HCPA), na condi????o de hospital de ensino, tem a pesquisa inserida no seu dia-a-dia e para a coordena????o dessas atividades, conta com o Grupo de Pesquisa e P??s-Gradua????o (GPPG). Sensibilizado com as dificuldades encontradas pelos pesquisadores para a realiza????o de seus projetos, o GPPG desenvolveu e implantou um novo modelo de gest??o de infra-estrutura da pesquisa, por meio de laborat??rios compartilhados e tem??ticos. Os resultados deste trabalho foram a redu????o da duplicidade de investimentos para o mesmo fim pelo uso racional de espa??o f??sico e equipamentos, a desvincula????o das atividades de pesquisa da rotina assistencial, a viabiliza????o de um local adequado para projetos com modelos animais. Como dividendo desta pr??tica, a troca de experi??ncias de forma sistem??tica e a maior integra????o dos pesquisadores resultaram num acr??scimo de projetos multidisciplinares na Institui????o

Revis??o de pre??os por meio de indicadores de mercado e par??metros da licita????o

A metodologia de revis??o de pre??os dos contratos de fornecedores, com base em indicadores de mercado e em suporte informatizado, foi desenvolvida e est?? sendo aperfei??oada, de forma a garantir a manuten????o do equil??brio econ??mico-financeiro dos 330 contratos de servi??os de transporte de terceiros. Dessa forma, buscam-se maior agilidade nos processos e informa????es confi??veis, de forma a assegurar justa remunera????o para a execu????o dos servi??os com a qualidade necess??ria e a um menor custo

An??lise da viabilidade de implanta????o de um escrit??rio de projetos como indutor de maturidade e de gest??o eficiente de projetos na ??rea-meio do Itamaraty

A monografia estudar?? a viabilidade de implanta????o de um Escrit??rio de Projetos na ??rea-meio do Itamaraty, a qual compreende as atividades de Recursos Humanos, Or??amento, Log??stica e Compras, Comunica????es, Inform??tica, Planejamento e Moderniza????o Administrativa. A forma de estrutura????o e a cultura organizacional hist??rica do MRE n??o t??m facilitado ?? sele????o criteriosa e a continuidade dos projetos na ??rea de suporte administrativo, o que produz impactos negativos nos resultados esperados para o ??rg??o. Com base no estudo dos procedimentos existentes e no grau de maturidade em gerenciamento de projetos, bem como da incorpora????o de boas pr??ticas em gest??o de projetos por meio da estrutura????o de um Escrit??rio de Projetos customizado ??s caracter??sticas do ??rg??o, ser?? poss??vel orientar e induzir a institui????o a executar projetos de forma eficiente, eficaz e orientada a resultados. Se um Escrit??rio de Projetos na ??rea administrativa for vi??vel, ser?? oportuno investigar sob quais premissas essa unidade poderia ser estruturada