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Cargo ships --- Bending stress --- Slamming
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Reliability (Engineering) --- Fractures materials --- Slamming
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Hulls (Naval architecture) --- Vibration --- Dynamic response --- Swelling --- Slamming --- Accelerometers --- Vibration tests
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Slamming impact on marine structures constitutes a major concern for designers. Characterized by severe impulsive loads with short duration, this highly non-linear fluid-structure interaction can lead to significant structural damage. Several analytical models have been developed to predict the loads generated on slamming events. However, existent models are still not sufficiently accurate to be applied on industrial level. This thesis presents a numerical slamming model developed with the ALE/Eulerian approach on LS-DYNA. Primarily, the classical two-dimensional rigid wedge is used for an overview on the functioning of the applied penalty contact algorithm and calibration of its governing parameters. The model is validated through comparison with experimental results of the vertical slamming force available on the literature. Sensitivity analyses on parameters such as the penalty factor, damping coefficient and number of coupling points are performed. Additionally, simulations with a three-dimensional version of the rigid wedge are presented with the objective of demonstrating the influence of 3D flow effects on the resulting force. The models produce satisfactory results, reproducing fairly well the slamming force and the free-surface behavior on the rigid structure. On a third stage, the model is applied to an elasto-plastic flat plate. Good agreement with experimental results is found for the hydro-elastic behavior of the plate. Accurate measurements of the local pressure, however, could not be obtained. The model is finally extended to a practical application proposed by the company Calcul- Méca, a fiber reinforced composite sonar dome subjected to slamming. As a preliminary approach, a two-dimensional model with an approximated parabolic rigid body is developed. However, results obtained are not conclusive. Severe leakage occurs on the Lagrangian structure and could not be properly fixed. The slamming force seems to be incoherent with the expected physical behavior. These issues are probably associated to the low deadrise angle of the parabola combined with the high imposed constant velocity, which create extreme conditions for the penalty contact algorithm.
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Telephone slamming --- Telephone cramming --- Long distance telephone service --- Consumer protection --- Law and legislation --- Corrupt practices --- State supervision --- United States. --- Rules and practice.
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Essential Computer Security provides the vast home user and small office computer market with the information they must know in order to understand the risks of computing on the Internet and what they can do to protect themselves.Tony Bradley is the Guide for the About.com site for Internet Network Security. In his role managing the content for a site that has over 600,000 page views per month and a weekly newsletter with 25,000 subscribers, Tony has learned how to talk to people, everyday people, about computer security. Intended for the security illiterate, Essential Computer Securit
Computer networks - Security measures. --- Computer security. --- Computers --- Electronic mail systems --- Firewalls (Computer security) --- Internet --- Spam filtering (Electronic mail) --- Spyware (Computer software) --- Access control --- Passwords. --- Security measures. --- Blocking, Spam (Electronic mail) --- Filtering, Spam (Electronic mail) --- Slamming spam (Electronic mail) --- Spam blocking (Electronic mail) --- Spam slamming (Electronic mail) --- Computer firewalls --- Internet firewalls --- Intranet firewalls --- Passwords in computer access control --- Computer privacy --- Computer system security --- Computer systems --- Cyber security --- Cybersecurity --- Electronic digital computers --- Security of computer systems --- Security measures --- Protection of computer systems --- Protection --- Malware (Computer software) --- Filters (Mathematics) --- Computer networks --- Data protection --- Security systems --- Hacking
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Cavitation refers to the formation of vapor cavities in a liquid when the local pressure becomes lower than the saturation pressure. In many hydraulic applications, cavitation is considered as a non-desirable phenomenon, as far as it may cause performance degradation, vibration problems, enhance broad-band noise-emission, and eventually trigger erosion. In this Special Issue, recent findings about cavitation instabilities are reported. More precisely, the dynamics of cavitation sheets are explored at very low Reynolds numbers in laminar flows, and in microscale applications. Both experimental and numerical approach are used. For the latter, original methods are assessed, such as smooth particles hydrodynamics or detached eddy simulations coupled to a compressible approach.
cavitation --- cavitation number --- globe valve --- valve cage --- computational fluid dynamics --- hydrodynamic cavitation --- compressible two-phase flow --- turbulence modelling --- system instabilities --- jet --- vortex --- mechanical surface treatment --- cavitation peening --- partial cavitation --- super-cavitation --- laminar cavitation --- cavitation instabilities --- vortex rope --- Francis turbine --- CFD --- RANS --- slamming --- fluid-structure interaction --- fluid detachment --- hydrofoil --- bulb turbine --- bulb turbine runner --- flow visualization --- cavitation tunnel --- regression model --- Kelvin-Helmholtz instability --- microchannel --- numerical simulation --- multifunction cavitation --- water jet cavitation --- ultrasonic cavitation --- high-temperature high-pressure cavitation --- peening natural aging --- low-temperature low-pressure cavitation --- peening aging --- Francis Turbine
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