Página 1 dos resultados de 69 itens digitais encontrados em 0.011 segundos

‣ Otimização das formas de cascos de deslocamento em relação a sua resistência ao avanço.; Displacement hull optimization regarding to ship wave resistance.

Alvarez, Rodrigo Loureiro Prado
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/02/2008 Português
Relevância na Pesquisa
58.21011%
Devido à constante necessidade de construções de novas embarcações, quer seja pela demanda do mercado, quer seja pela renovação da frota, o desenvolvimento de programas computacionais que auxiliem na fase inicial de projeto torna-se bastante útil. Assim, o desenvolvimento de um procedimento de análise que permita obter formas de melhor desempenho vem a agregar valor nesta etapa de conceituação da geometria do navio. O trabalho aqui apresentado tem como objetivo discorrer sobre um método capaz de otimizar a geometria de um casco de deslocamento conhecido em relação a sua resistência ao avanço, sem perder, porém, as suas características principais, como corpo paralelo médio, por exemplo. Para tanto, dentro deste processo de otimização já estão inseridas algumas restrições que garantem a viabilidade da solução final, tais como variação máxima no comprimento, no volume total e na estabilidade do navio. A modelagem da embarcação pode ser feita através de funções B-Splines cúbicas de superfície, cujos pontos de controle (parâmetros inerentes à função) podem ser modificados de tal sorte a atingir um valor ótimo para a resistência ao avanço. Esta, por sua vez, será obtida através da soma de duas parcelas...

‣ Efeito da superestrutura sobre a resistência longitudinal de embarcações de pequeno porte: aplicação e análise estrutural para um navio militar da Marinha Colombiana.; Effect of the superstructure on the longitudinal resistance of the small vessel: application and structural analysis for Colombian Naval vessel.

Mojica Valero, Carlos Alberto
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 19/06/2008 Português
Relevância na Pesquisa
37.100007%
O propósito do presente trabalho é desenvolver a avaliação estrutural de um navio "Nodriza" de pequeno porte de aplicação militar e cujo projeto inicial foi orientado à navegação em águas abrigadas com restrições de calado. Porém, requisitos e necessidades afetando a concepção inicial do projeto obrigam este a efetuar percursos em águas profundas com possibilidade de experimentar ciclos de onda. A avaliação estrutural pretende determinar o nível de influência da superestrutura sobre a resistência longitudinal do navio considerando-o submetido a esforços solicitantes próprios de águas não abrigadas. As limitações geradas pelas formas e proporções do navio Nodriza, que não permitem implementar de forma direta as regras de Sociedades Classificadoras para a avaliação estrutural em águas profundas, obriga ao uso de cálculos diretos para sua aprovação. Uma análise mediante o uso de elementos finitos, modelando o navio com e sem participação da superestrutura, permite determinar como esta representa uma significativa influência sobre a resistência longitudinal e tensões finais dos membros principais e membros de suporte, quando é considerada dentro da análise estrutural. Igualmente, implementam-se procedimentos determinísticos propostos pelas regras de sociedades classificadoras para navios convencionais...

‣ Projeto preliminar de sistema propulsivo de uma embarcação de apoio offshore do tipo platform supply vessel

Schoeping, Djonatan
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: Trabalho de Conclusão de Curso Formato: xx f.
Português
Relevância na Pesquisa
27.537297%
TCC (graduação) - Universidade Federal de Santa Catarina. Campus Joinville. Engenharia Naval.; As embarcações de apoio a plataformas (offshore) de petróleo surgiram para fornecer auxílio especializado na logística petrolífera. Dentre estas embarcações de apoio offshore estão às embarcações do tipo Platform Supply Vessel (PSV). Nesta logística petrolífera, um navio que possui um sistema propulsivo ineficaz ocasionará apoio deficiente, trazendo prejuízos para a cadeia produtiva do setor. Destaca-se em um projeto preliminar de um sistema propulsivo as seguintes etapas: escolha do tipo de sistema propulsivo, estimativa de resistência ao avanço da embarcação, dimensionamento dos componentes que compõe o sistema e desenvolvimento do arranjo preliminar da instalação propulsora. O projeto preliminar do sistema propulsivo deste trabalho foi baseado nas dimensões da embarcação Bram Brasil. O sistema propulsão selecionado para esta embarcação foi o diesel-elétrico com hélice de passo variável devido à sua flexibilidade e operabilidade. Para aperfeiçoar os processos de cálculo foram criados códigos no programa MATLAB®. Nestes algoritmos podem ser encontrados: a estimativa de resistência ao avanço pelo método de Holtrop e Mennen...

‣ Projeto preliminar de sistema propulsivo de uma embarcação de apoio offshore do tipo platform supply vessel

Schoeping, Djonatan Guilherme Erbs
Fonte: Joinville Publicador: Joinville
Tipo: Trabalho de Conclusão de Curso Formato: 75 f.
Português
Relevância na Pesquisa
27.537297%
TCC (graduação) - Universidade Federal de Santa Catarina. Campus Joinville. Engenharia Naval.; As embarcações de apoio a plataformas (offshore) de petróleo surgiram para fornecer auxílio especializado na logística petrolífera. Dentre estas embarcações de apoio offshore estão às embarcações do tipo Platform Supply Vessel (PSV). Nesta logística petrolífera, um navio que possui um sistema propulsivo ineficaz ocasionará apoio deficiente, trazendo prejuízos para a cadeia produtiva do setor. Destaca-se em um projeto preliminar de um sistema propulsivo as seguintes etapas: escolha do tipo de sistema propulsivo, estimativa de resistência ao avanço da embarcação, dimensionamento dos componentes que compõe o sistema e desenvolvimento do arranjo preliminar da instalação propulsora. O projeto preliminar do sistema propulsivo deste trabalho foi baseado nas dimensões da embarcação Bram Brasil. O sistema propulsão selecionado para esta embarcação foi o diesel-elétrico com hélice de passo variável devido à sua flexibilidade e operabilidade. Para aperfeiçoar os processos de cálculo foram criados códigos no programa MATLAB®. Nestes algoritmos podem ser encontrados: a estimativa de resistência ao avanço pelo método de Holtrop e Mennen...

‣ Ship transport of marine invasive species and its stress resistance

Antunes, Filipa Alexandra Paiva
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Dissertação de Mestrado
Português
Relevância na Pesquisa
27.537297%
In the context of biological invasions, ship transport plays an important role in the transference of species around the world. During this process organisms are exposed to several stressful conditions, which do not prevent them to arrive in areas where they did not occur before. The marine invertebrates Carcinus maenas and Mytilus galloprovincialis natives in Portugal, have already established stable invasive populations in several regions worldwide. This study exposed organisms of both species to stress conditions similar to what occurs in ballast tanks and on ship hulls. Results showed a high survival of pre-stressed Mytilus galloprovincialis individuals when compared to non pre-stressed organisms when exposed to air exposure, hyposalinity and heat events. However when Carcinus maenas was exposed to heat stress, there was no significant difference between groups with a different stress history. These findings suggest that transport on ships is not only a vector of dispersal but also a vector capable to increase the resistance to stress conditions in potential species invaders by selection of resistant individual; Resumo: "Transporte marítimo de espécies marinhas invasoras e sua resistência ao stress" No contexto das invasões biológicas...

‣ Differential Regulation of B Cell Development, Activation, and Death by the Src Homology 2 Domain–Containing 5′ Inositol Phosphatase (Ship)

Brauweiler, Anne; Tamir, Idan; Dal Porto, Joseph; Benschop, Robert J.; Helgason, Cheryl D.; Humphries, R. Keith; Freed, John H.; Cambier, John C.
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/05/2000 Português
Relevância na Pesquisa
27.74479%
Although the Src homology 2 domain–containing 5′ inositol phosphatase (SHIP) is a well-known mediator of inhibitory signals after B cell antigen receptor (BCR) coaggregation with the low affinity Fc receptor, it is not known whether SHIP functions to inhibit signals after stimulation through the BCR alone. Here, we show using gene-ablated mice that SHIP is a crucial regulator of BCR-mediated signaling, B cell activation, and B cell development. We demonstrate a critical role for SHIP in termination of phosphatidylinositol 3,4,5-triphosphate (PI[3,4,5]P3) signals that follow BCR aggregation. Consistent with enhanced PI(3,4,5)P3 signaling, we find that splenic B cells from SHIP-deficient mice display enhanced sensitivity to BCR-mediated induction of the activation markers CD86 and CD69. We further demonstrate that SHIP regulates the rate of B cell development in the bone marrow and spleen, as B cell precursors from SHIP-deficient mice progress more rapidly through the immature and transitional developmental stages. Finally, we observe that SHIP-deficient B cells have increased resistance to BCR-mediated cell death. These results demonstrate a central role for SHIP in regulation of BCR signaling and B cell biology, from signal driven development in the bone marrow and spleen...

‣ MiR-155 Induction by F. novicida but Not the Virulent F. tularensis Results in SHIP Down-Regulation and Enhanced Pro-Inflammatory Cytokine Response

Cremer, Thomas J.; Ravneberg, David H.; Clay, Corey D.; Piper-Hunter, Melissa G.; Marsh, Clay B.; Elton, Terry S.; Gunn, John S.; Amer, Amal; Kanneganti, Thirumala-Devi; Schlesinger, Larry S.; Butchar, Jonathan P.; Tridandapani, Susheela
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 30/12/2009 Português
Relevância na Pesquisa
27.719485%
The intracellular Gram-negative bacterium Francisella tularensis causes the disease tularemia and is known for its ability to subvert host immune responses. Previous work from our laboratory identified the PI3K/Akt pathway and SHIP as critical modulators of host resistance to Francisella. Here, we show that SHIP expression is strongly down-regulated in monocytes and macrophages following infection with F. tularensis novicida (F.n.). To account for this negative regulation we explored the possibility that microRNAs (miRs) that target SHIP may be induced during infection. There is one miR that is predicted to target SHIP, miR-155. We tested for induction and found that F.n. induced miR-155 both in primary monocytes/macrophages and in vivo. Using luciferase reporter assays we confirmed that miR-155 led to down-regulation of SHIP, showing that it specifically targets the SHIP 3′UTR. Further experiments showed that miR-155 and BIC, the gene that encodes miR-155, were induced as early as four hours post-infection in primary human monocytes. This expression was dependent on TLR2/MyD88 and did not require inflammasome activation. Importantly, miR-155 positively regulated pro-inflammatory cytokine release in human monocytes infected with Francisella. In sharp contrast...

‣ Ship Trim Optimization: Assessment of Influence of Trim on Resistance of MOERI Container Ship

Sherbaz, Salma; Duan, Wenyang
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 20/01/2014 Português
Relevância na Pesquisa
27.873054%
Environmental issues and rising fuel prices necessitate better energy efficiency in all sectors. Shipping industry is a stakeholder in environmental issues. Shipping industry is responsible for approximately 3% of global CO2 emissions, 14-15% of global NOX emissions, and 16% of global SOX emissions. Ship trim optimization has gained enormous momentum in recent years being an effective operational measure for better energy efficiency to reduce emissions. Ship trim optimization analysis has traditionally been done through tow-tank testing for a specific hullform. Computational techniques are increasingly popular in ship hydrodynamics applications. The purpose of this study is to present MOERI container ship (KCS) hull trim optimization by employing computational methods. KCS hull total resistances and trim and sinkage computed values, in even keel condition, are compared with experimental values and found in reasonable agreement. The agreement validates that mesh, boundary conditions, and solution techniques are correct. The same mesh, boundary conditions, and solution techniques are used to obtain resistance values in different trim conditions at Fn = 0.2274. Based on attained results, optimum trim is suggested. This research serves as foundation for employing computational techniques for ship trim optimization.

‣ Nonlinear ship waves and computational fluid dynamics

MIYATA, Hideaki; ORIHARA, Hideo; SATO, Yohei
Fonte: The Japan Academy Publicador: The Japan Academy
Tipo: Artigo de Revista Científica
Publicado em 10/10/2014 Português
Relevância na Pesquisa
27.536633%
Research works undertaken in the first author’s laboratory at the University of Tokyo over the past 30 years are highlighted. Finding of the occurrence of nonlinear waves (named Free-Surface Shock Waves) in the vicinity of a ship advancing at constant speed provided the start-line for the progress of innovative technologies in the ship hull-form design. Based on these findings, a multitude of the Computational Fluid Dynamic (CFD) techniques have been developed over this period, and are highlighted in this paper. The TUMMAC code has been developed for wave problems, based on a rectangular grid system, while the WISDAM code treats both wave and viscous flow problems in the framework of a boundary-fitted grid system. These two techniques are able to cope with almost all fluid dynamical problems relating to ships, including the resistance, ship’s motion and ride-comfort issues. Consequently, the two codes have contributed significantly to the progress in the technology of ship design, and now form an integral part of the ship-designing process.

‣ A preliminary design tool for resistance and powering prediction of catamaran vessels

Zouridakis, Fragiskos
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 144 p.; 7290379 bytes; 7296440 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
27.438855%
During the last decade catamaran ships have been very rapidly evolved into a dominant mode of sea transportation. Their particular area of proliferation is the short sea shipping where they show considerable superiority over competitive designs in attributes such as power requirements, economy, space availability and seakeeping. The rapid growth of the market has led to the need for an expanded range of catamaran designs in terms of size, speed, and payload diversity (passengers, vehicles, containers). However, even now, there is a scarcity of publicly available preliminary design tools for catamarans. This fact hinders the ship owner and naval architect from being able to quickly assess the relative merits of alternative potential designs without having to resort to expensive expert consultancy solutions. Resistance characteristics and power requirements are principal aspects of the catamaran design spiral as they are strongly coupled with speed and fuel economy, and, consequently, the operating and cost efficiencies of the vessel. This thesis aims towards the development of a tool that predicts the resistance and required power for catamaran vessels in the range of 20m to 80m. Vessels with both round bilge and hard chine hulls are considered.; (cont.) Reasonable accurate prediction may be achieved for all speed regions of intended operation. (Displacement...

‣ 13.400 Introduction to Naval Architecture, Fall 2004; Introduction to Naval Architecture

Herbein, David; McCoy, Timothy J. (Timothy John)
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Português
Relevância na Pesquisa
47.873057%
Introduction to principles of naval architecture, ship geometry, hydrostatics, calculation and drawing of curves of form, intact and damaged stability, hull structure strength calculations and ship resistance. Projects include analysis of ship lines drawings and ship model testing.

‣ Calculation of the second order mean force on a ship in oblique seas.

Erb, Paul Ross
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 181 leaves
Português
Relevância na Pesquisa
37.09951%
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1977.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography: leaves 114-116.

‣ Comparison of four simple wave resistance formulas

Koch, Pierre Francois
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 126 leaves
Português
Relevância na Pesquisa
37.028223%
by Pierre Francois Koch.; Thesis (Ocean E)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Includes bibliographical references.

‣ Wave making resistance characteristics of trimaran hulls

Elcin, Zafer
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
37.559268%
Approved for public release; distribution is unlimited; Recently, there has been an increased demand for high speed vessels both for military and commercial applications. Many navies are exploring the potential of novel hull forms as part of efforts to achieve transformation in both combat and logistics missions in littoral seas. This demand for high speed vessels has resulted in a need for unconventional hull forms in order to balance speed with payload requirements. One such hull form is the trimaran. The purpose of this thesis is to investigate the effects of side hull position on the wave making resistance characteristics of powered trimarans. Resistance calculations were performed by a three dimensional, Rankine panel code. A systematic series of runs was conducted in order to classify ship resistance in terms of major trimaran hull geometric configurations. The results of this thesis can be directly utilized in design, in order to minimize ship resistance, and maximize available payload.

‣ Predicting Ship Fuel Consumption: Update

Schrady, David A.; Smyth, Gordon K.; Vassian, Robert Bruce
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Relatório
Português
Relevância na Pesquisa
27.601394%
This report is concerned with the prediction of ship propulsion fuel consumption as a function of ship speed for U.S. Navy combatant and auxiliary ships. Prediction is based on fitting an analytic function to published ship class speed-fuel use data using nonlinear regression. The form of the analytic function fitted is motivated by the literature on ship powering and resistance. The report discusses data sources and data issues, and the impact of ship propulsion plant configuration on fuel use. The regression coefficients of the exponential function fitted, tabular numerical comparison of predicted and actual fuel use data, the standard error of the estimate, and plots of actual and fitted data are given for 22 classes of Navy ships

‣ Comparative resistance calculations for SLICE/SWATH hulls

Al-jowder, Jassim Abdulla
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
27.51064%
Comparative resistance calculations are performed for SLICE and SWATH hulls. For the purposes of this study, the primary difference between these two hull types is in the underwater pods. It is assumed that both ship types have identical surface piercing struts, speed, and displacement. The underwater pods are continuous for the SWATH design and discontinuous for the SLICE. Resistance calculations are based on I.T.T.C. skin friction, empirical regression of existing experimental data for form drag, and surface singularities distribution for wavemaking. Results are presented for two cases, length limited where the overall length between the two hull types remains constant, and diameter limited where the pod diameter remains constant. Parametric studies in terms of pod geometry, separation distance, ship speed, displacement length ratio, and draft indicate that a SLICE hull may offer decreased resistance compared to a similar SWATH, depending on the range of the above design parameters. (AN)

‣ Design Space Exploration and Optimization Using Modern Ship Design Tools

Jones, Adam
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
27.68868%
CIVINS; Modern Naval Architects use a variety of computer design tools to explore feasi- ble options for clean sheet ship designs. Under the Naval Sea Systems Command (NAVSEA), the Naval Surface Warfare Center, Carderock Division (NSWCCD) has created computer tools for ship design and analysis purposes. This paper presents an overview of some of these tools, speci cally the Advanced Ship and Submarine Evaluation Tool (ASSET) version 6.3 and the Integrated Hull Design Environment (IHDE). This paper provides a detailed explanation of a ship design using these ad- vanced tools and presents methods for optimizing the performance of the hullform, the selection of engines for fuel e ciency, and the loading of engines for fuel e ciency. The detailed ship design explores the design space given a set of speci c requirements for a cruiser-type naval vessel. The hullform optimization technique reduces a ships residual resistance by using both ASSET and IHDE in a Design of Experiments (DoE) approach to reaching an optimum solution. The paper will provide a detailed example resulting in a 12% reduction in total ship drag by implementing this technique on a previously designed hullform. The reduction of drag results in a proportional reduction in the amount of fuel used to push the ship through the water. The engine selection optimization technique uses MATLAB to calculate the ideal engines to use for fuel minimization. For a given speed-time or power-time pro le...

‣ Resistance, wave-making and wave-decay of thin ships, with emphasis on the effects of viscosity.

Lazauskas, Leo Victor
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2009 Português
Relevância na Pesquisa
38.185513%
Three interrelated topics in ship hydrodynamics - resistance, wave-making and wave decay - are investigated in an attempt to improve the accuracy of some simple methods used in the preliminary design of thin ships. Several published sets of data from classical and recent boundary layer experiments on flat plates are used to estimate boundary layer quantities such as thicknesses and eddy viscosities. These quantities are subsequently used to modify the hull shape and the free-surface boundary condition as a means of including viscous effects on wave-making and ship-wave decay. A recent technique is used to analyse 161 experimental flat-plate turbulent boundary layer velocity profiles, and a new skin-friction line is derived. Some practical methods are proposed for the numerical quadrature of integrals arising in thin-ship hydrodynamics. We demonstrate that for some integrals, rapid oscillation, rather than being a hindrance to accurate quadrature, can actually be beneficial if appropriate techniques are employed. We find that boundary layer displacement thickness effects on wave resistance are very small and can be safely ignored for full-size vessels. On the other hand, the idea of a detachment layer, an indication of where the boundary layer begins to thicken rapidly...

‣ Hydrodynamics of advanced high-speed sealift vessels.

Lazauskas, Leo V.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 803327 bytes; 210569 bytes; application/pdf; application/pdf
Publicado em //2005 Português
Relevância na Pesquisa
37.59439%
There is at present great interest in large ships capable of carrying substantial cargo at speeds in excess of 40 knots. At the same time, there are large gaps in our understanding of the hydrodynamics, structural engineering, and economics of high-speed vessels. Monohulls, catamarans, trimarans, surface effect ships, and air cushion vehicles are considered in the present work. The total resistance of these vehicles is divided into separate components which are estimated using different methods. Skin-friction is estimated using Grigson's algorithm which gives much better predictions of flat plate skin-friction than the traditional ITTC method. Wave resistance of displacement hulls is estimated using Michell's thin-ship theory: a similar theory is used for the wave resistance of travelling pressure distributions. Several simple formulae are derived that can be used in the preliminary design stage of catamarans to estimate optimum demihull separation. Memetic algorithm techniques are used to find vessels with minimum (calm-water) total resistance. Optimal geometric parameters are found for vessels of 1200 tonnes under a variety of geometric limitations and constraints on upright stability, at design speeds of 50 knots and 75 knots. Estimates are made of the principal weight components of the optimal vessels. Empirical formulae for the efficiencies of powerplants and propulsors then enable estimates to be made of the maximum range...

‣ A theoretical and numerical determination of optimal ship forms based on Michell's wave resistance

Dambrine, Julien; Pierre, Morgan; Rousseaux, Germain
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/10/2014 Português
Relevância na Pesquisa
27.559268%
We determine the parametric hull of a given volume which minimizes the total water resistance for a given speed of the ship. The total resistance is the sum of Michell's wave resistance and of the viscous resistance, approximated by assuming a constant viscous drag coefficient. We prove that the optimized hull exists, is unique, symmetric, smooth and that it depends continuously on the speed. Numerical simulations show the efficiency of the approach, and complete the theoretical results.