Hill Instability Analysis Of Tlp Tether Subjected To Combined Platform Surge And Heave Motions

This paper presents the Hill instability analysis of Tension Leg Platform (TLP) tether it, deep sea. The 2-D nonlinear beam model which is Undergoing Coupled axial and transverse vibrations, is applied. The governing equations are reduced to nonlinear Hill equation by use of the Galerkin's method and the modes superposition principle. The Hill instability charted Lip to large parameters is obtained. An important parameter M is defined and can he expressed as the functions of tether length, the platform surge and heave motion amplitudes. Some example studies are performed for various environmental conditions. The results demonstrate that the nonlinear coupling between the axial and transverse vibrations has a significant effect on the response of structure.. It needs to be considered for the accurate dynamic analysis of long TLP tether subjected to the combined platform surge and heave motions.

High Aspect Ratio (L/D) Riser Viv Prediction Using Wake Oscillator Model

A two-dimensional (2-D) vortex-induced vibration (VIV) prediction model for high aspect ratio (LID) riser subjected to uniform and sheared flow is studied in this paper. The nonlinear structure equations are considered. The near wake dynamics describing the fluctuating nature of vortex shedding is modeled using classical van der Pol equation. A new approach was applied to calibrate the empirical parameters in the wake oscillator model. Compared the predicted results with the experimental data and computational fluid dynamic (CFD) results. Good agreements are observed. It can be concluded that the present model can be used as simple computational tool in predicting some aspects of VIV of long flexible structures. (C) 2008 Elsevier Ltd. All rights reserved.

Enhanced cycling performance and high energy density of LiFePO4 based lithium ion batteries

LiFePO4 attracts a lot of attention as cathode materials for the next generation of lithium ion batteries. However, LiFePO4 has a poor rate capability attributed to low electronic conductivity and low density. There is seldom data reported on lithium ion batteries with LiFePO4 as cathode and graphite as anode. According to our experimental results, the capacity fading on cycling is surprisingly negligible at 1664 cycles for the cell type 042040. It delivers a capacity of 1170 mAh for 18650 cell type at 4.5C discharge rate. It is confirmed that lithium ion batteries with LiFePO4 as cathode are suitable for electric vehicle application. (c) 2007 Elsevier B.V. All rights reserved.

Educar para la democracia : Tocqueville y Sarmiento: dos visiones de la educación para una democracia republicana

Resumen: Estados Unidos de América ofreció a Domingo Faustino Sarmiento y a Alexis de Tocqueville una opción de modelo inigualable para el contexto de renovación social que necesitaban sus países de origen. Su experiencia llevó a ambos a forjar una teoría basada en la función de la educación como engranaje de la democracia Americana. El presente trabajo se subsume en el espacio dado por estos autores al Estado y a la religión como eje fundacional de una sociedad y su ejercicio de gobierno democrático.

Sarmiento y su visión militar

Resumen: Las grandes naciones se construyen a partir de la visión alentadora de un grupo de hombres, que en la comprensión cabal de la realidad son capaces de encontrar las soluciones necesarias. Para el estadista ningún asunto puede reconocerse sin su relación con el otro y todos adquieren importancia en tanto puedan contribuir al desarrollo nacional y el bienestar ciudadano. En Sarmiento, la educación habría de ser el origen, y su realización, el instrumento inapelable en la construcción de un estado moderno. En este esquema las instituciones aparecen como los pilares sobre los que se apoya la verdadera esencia del espíritu nacional, y el único sostén legítimo del Estado; de allí la preocupación por su consolidación. A la organización de la política, de la justicia y de la administración en general, Sarmiento sumó un interés medular en torno al fortalecimiento del Ejército y la Armada, que tuvo como punto de partida las guerras civiles argentinas, continuidad con la experiencia adquirida en los Estados Unidos y su afirmación tras las consecuencias de la guerra con el Paraguay. Esta investigación aborda los aspectos más profundos de su pensamiento castrense, materializado en obra a partir de un agudo trabajo de organización desarrollado a lo largo de sus servicios militares, y en la presidencia de la Nación con la adquisición de modernos armamentos y la creación de las primeras escuelas para oficiales.

Diário da Constituinte [gravação de vídeo] : [programa n. 718]

Discurso de encerramento das votações do Projeto de Constituição proferido pelo Presidente da Assembleia Nacional Constituinte Deputado Ulysses Guimarães e comemoração dos deputados constituintes. Frase de Ulysses Guimarães: "A pátria como a casa de todos". Plenário cheio, chuva de papel picado, Hino Nacional cantado pelos constituintes.

A Amazonia : as provincias do Pará e Amazonas e o governo central do Brazil

O Barão de Marajó relata a situação da Amazônia (Pará e Amazonas) em relação ao governo central.

Recommendation domains for pond aquaculture: country case study: development and status of freshwater aquaculture in Bangladesh

This report is an output of the project “Determination of high-potential aquaculture development areas and impact in Africa and Asia”. This monograph is the case study for Cameroon. Written in three parts, it describes the historical background, practices, stakeholder profiles, production levels, economic and institutional environment, policy issues, and prospects for aquaculture in the country. First, it documents the history and current status of the aquaculture in the country. Second, it assesses the technologies and approaches that either succeeded or failed to foster aquaculture development and discusses why. Third, it identifies the key reasons for aquaculture adoption.

New fish populations as evidence of climate chage in former dry areas of the Pampa Region ( Southern South America).

Water bodies located at 34º 58' S, 62º 58' W formed after 1980 by 30 % increasing rainfall during the last half century, were colonized by ten fish species which are a subset of the commonest species living in the pampasic lagunas. These new populations imply a displacement of the West of Pampasian fishes to areas of the western basins previously lacking fish.

Nonlinear Dynamic Response of Tension Leg Platform

Tension Leg Platform (TLP) is a typical compliant offshore structure for oil exploitation in deep water. Most of the existing mathematical models for analyzing the dynamic response of TLP are based on explicit or implicit assumptions that displacements (translations and rotations) are small magnitude. Herein a theoretical method for analyzing the nonlinear dynamic behavior of TLP with finite displacement is developed, in which multifold nonlinearities are taken into account, i.e. finite displacement, coupling of the six degrees of freedom, instantaneous position, instantaneous wet surface, free surface effects and viscous drag force. Using this theoretical model, we perform the numerical analysis of dynamic response of a representative TLP. The comparison between the degenerative linear solution of the proposed nonlinear model and the published one shows good agreements. Furthermore, numerical results are presented which illustrate that nonlinearities exert a distinct influence on the dynamic responses of the TLP.