Creep buckling of shells of revolution loaded under uniform external pressure

Sullivan, Paul F.

doi:10.1575/1912/3216

Cited by 3 publications

(3 citation statements)

References 2 publications

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“…Voorhis and Benoit (1975) attributed this to slow creeping of the aluminum under pressure which slowly decreased the float's volume. Sullivan (1975) made measurements of aluminum creep rates supporting this hypothesis and predicted a strong dependence of the creep rate on pressure. As a result, the slow descent of floats at depth has generally been attributed to metal creep, despite the lack of an observed correlation between float descent rates and pressure (Richardson and Schmitz 1983) and despite the fact that the Sullivan (1975) creep rates are far higher than those found in the literature (J. Osse, personal communication, 1996).…”

Section: Float Physical Parameters a Overviewmentioning

confidence: 79%

Performance of Autonomous Lagrangian Floats

D’Asaro¹

2003

J. Atmos. Oceanic Technol.

131

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A truly Lagrangian float would follow all three components of oceanic velocity on all time scales. Progress toward this goal is reviewed by analyzing the performance of nearly Lagrangian floats deployed in a variety of oceanic flows. Two new float types, described in this paper, are autonomous with durations of months, can alternate between Lagrangian and profiling modes, relay data via satellite, and can carry a variety of sensors. A novel hull design is light, strong, and has a compressibility close to that of seawater.The key to making floats accurately Lagrangian is an improved understanding of the factors that control float buoyancy and motion. Several insights are presented here. Anodized aluminum gains weight in seawater due to reactions between its surface and seawater. At low pressure the buoyancy of floats with O-ring seals varies as if attached bubbles of air were being compressed.The volume of "air" decays exponentially with a decay scale of a few decays from 10-30 cc at deployment to an asymptotic value which depends on pressure. The drag of floats moving slowly through a stratified ocean is dominated by internal wave generation and is thus linear, not quadratic. Internal wave drag acting on an isopycnal-seeking float will cause the float to be Lagrangian for frequencies greater than about N/30, where N is the buoyancy frequency. These floats have proven most useful in measuring the turbulence in ocean boundary layers and other regions of strong turbulence where the ability of the floats to be Lagrangian on short time scales matches the short times scale of the processes and where the size of the turbulent eddies exceeds the size of the float. On longer time scales, the floats successfully operate as isopycnal followers. Because truly Lagrangian floats are highly sensitive to minor perturbations, extension of the frequency band over which the floats are Lagrangian will require careful control of float buoyancy and thus a detailed understanding of the float's equation of state. A n t e n n a T e m p e r a t u r e P r e s s u r e H u l l RAFOS Hydrophone D a c r o n D r o g u e Volume Control Piston Underneath Drop Weight Figure 1: The Deep Lagrangian Float, DLF. The float's buoyancy is controlled by a piston that pushes out of the bottom endcap. Pressure and temperature are measured through the top endcap. Long-range acoustic tracking is provided by RAFOS. The cloth drogue folds upwards for deployment. The drop weight and drogue fall off at the end of the mission, causing the float to surface. recent designs, therefore, have used folding cloth drogues. Estimation and control of the relative motion of the float and the water therefore depends on the drag law for the float at low velocity. Section 6 describes our improved understanding of drag. The most basic measurement made by Lagrangian floats is the position of the floats. The vertical position is measured from pressure and the vertical velocity from its rate of change. The horizontal velocity is more difficult to measure; acoustic tracking has been...

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Section: Float Physical Parameters a Overviewmentioning

confidence: 79%

Performance of Autonomous Lagrangian Floats

D’Asaro¹

2003

J. Atmos. Oceanic Technol.

131

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“…To benefit from that, project participants must have certain level of software development culture, based on past experience and personal self-development efforts. This implies management's ability to hire and keep exceptionally gifted people [2].…”

Section: Resumementioning

confidence: 99%

“…Automatic test cases should be written for each feature, conditional branch, and parameters set, including unused branches and edge cases. In case of large projects, where complete testing is not possible, at least all main functions must be tested before closing the project [2]. Before implementing any new feature, longer than 1 man-month, a prototype should be created and tested.…”

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confidence: 99%

Technical Optimization of Cross-Platform Software Development Process Quality and Usability of 3rd-Party Tools

Kondratyev

2016

ITE

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The article exposes developer's point of view on minimizing creation, upgrade, postrelease problem solving time for applications and components, targeted to multiple operating systems, while keeping high end product quality and computational performance. Non-uniformity of analogous tools and components, available on different platforms,causes strong impact on developer's productivity. In part., differences in 3rd-party component interfaces, versions, quality of distinct functions, cause frequent switching developer's attention on issues not connected (in principle) with the target project. While loss of development performance because of attention specifics is more subjective value, at least physical time spent on tools/components misbehavior compensation and normal tools configuring is measurable. So, the main thesis verified is whether it's possible to increase continuity of the development process by technical improvements only, and by which value. In addition, a novel experimental tool for interactive code execution is described, allowing for deep changes in the working program without its restart. Question under research:minimizing durations of programming-build-test-correct loop and small code parts runs, in part.,improving the debugging workflow for the account of combining the interactive editor and the debugger.

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SOFAR floats for POLYMODE

Webb

1977

OCEANS '77 Conference Record

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The design of a neutrally buoyant float and associated tracking and support equipment developed for the POLYMODE experiment is described. Floats with a signaling range of 1500 Km and an endurance of 2-1/2 years signal via the deep sound channel to both land based receiving stations and moored, portable receivers. Recordings of float signals are collected and centrally processed, providing both daily positions and two-day averages of temperature and pressure measured at each float. Floats are equipped with both a simple, active controller to insure isobaric operation, and a relocation and recovery capability.Background

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Creep buckling of shells of revolution loaded under uniform external pressure

Cited by 3 publications

References 2 publications

Performance of Autonomous Lagrangian Floats

Performance of Autonomous Lagrangian Floats

Technical Optimization of Cross-Platform Software Development Process Quality and Usability of 3rd-Party Tools

SOFAR floats for POLYMODE

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