Walden Robert G.

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Walden
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Robert G.
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  • Technical Report
    The design, logistics and installation of a SOFAR float tracking station at Grand Turk Island, B.W.I.
    (Woods Hole Oceanographic Institution, 1973-10) Walden, Robert G. ; Berteaux, Henri O. ; Striffler, Foster L.
    The Mid-Ocean Dynamics Experiment (MODE) under the Office of the International Decade of Oceanography, National Science Foundation, included plans for the deployment of long-range SOFAR floats in a two degree square area approximately 400 miles Southwest of Bermuda. The floats are located by AFETR, MILS system hydrophones at Bermuda, Eleuthera and Puerto Rico. An additional station at Grand Turk Island, British West Indies, was requested to provide an expanded and more reliable location. In addition a spare installation was to be provided which could be installed within relatively short notice at Eleuthera or Puerto Rico if required. The design, logistical considerations and installation of the Grand Turk Island station are documented in this report.
  • Technical Report
    The design, construction and testing of Loran-C from a drifting buoy
    (Woods Hole Oceanographic Institution, 1980-12) Collins, Clayton W. ; Walden, Robert G.
    A low-windage, current-following spar buoy system containing an automatic Loran-C navigation receiver and a single sideband transmitter with associated control circuitry is described. The Loran-C unit acquires and tracks Loran-C signals and, at intervals controlled by an onboard timer, produces a digital message which modulates the transmitter. The transmitter sends this message via a radio telemetry link to a base or ship receiving station where it is decoded. The decoder displays the message contents in the form of Loran-C time differences representing two lines of position, and thus a geographic fix. The system enables the position of the buoy to be tracked as it drifts with the current and thus serves as an instrument in measuring surface and near-surface current transport. A physical description, details of electrical and mechanical design, and test results, are documented in this report. Feasibility of the system was proven, and a pre-prototype system built and tested.
  • Technical Report
    Bottom-mounted profiling winch
    (Woods Hole Oceanographic Institution, 1984-03) Walden, Robert G. ; Collins, Clayton W.
    A winch has been developed which can be free-dropped to the ocean bottom in full ocean depths. The winch is powered by self-contained batteries and can be programmed to cycle self-recording instruments from close to the bottom to 100 meters above the bottom continuously or in steps. A typical scenario is envisioned as one complete cycle per day for one year with the instruments pausing each five meters for two minutes while measurements of current, temperature and conductivity are made. The upper section of the tripod contains the winch and instrumentation and is recovered by sending an acoustic command to a release mechanism allowing it to come to the surface.
  • Technical Report
    Performance analysis of Woods Hole taut moorings
    (Woods Hole Oceanographic Institution, 1973-06) Walden, Robert G. ; Panicker, Narayana N.
    The Woods Hole Oceanographic Institution has been using deepsea moored buoys for acquiring serial observations of ocean currents, temperature .and other data for over twelve years. A brief description of the deep-sea mooring program is given. The mooring statistics and performance are described. Mooring failures of 1970 and 1971 have been categorized and statistics on the modes and causes of failures are presented. The reliabilities of different types of moorings are computed and compared. The role of radio telemetry for the real-time measurement of mooring line tension and its use in checking the mooring status are discussed. Examples of potential design data like tension and currents recorded by moorings that failed are provided. Finally, recommendations for research and development needed to improve mooring reliability are given.
  • Technical Report
    Experimental evaluation of CTD package hydrodynamic behavior and recommendations for improved lowering techniques
    (Woods Hole Oceanographic Institution, 1983-07) Berteaux, Henri O. ; Walden, Robert G. ; Clay, Peter R. ; McDevitt, R. E.
    This report is the last of a series of three reports on a comprehensive study of CTD instrument lowering mechanics. The first report, WHOI 79-81, "A Study of CTD Cables and Lowering Systems", examines the causes and modes of lowering cable failures, both mechanical and electrical, and makes recommendations to improve existing instrument packages and lowering procedures. The second report, WHOI 81-76, "Hydrodynamics of CTD Instrument Packages", is a theoretical study of instrument package stability when cable lowered or free falling. The model is used to predict the hydrodynamic response of CTD packages in their present or improved configuration. This report, WHOI 83-21, is more factual. It describes the tests performed on scale models and actual CTD packages to actually observe and/or measure their hydrodynamic behavior. Analytical results and experimental data obtained in this study are used to draw recommendations for CTD package improvement and future lowering procedures.
  • Technical Report
    Self deployable deep sea moorings
    (Woods Hole Oceanographic Institution, 1992-01) Berteaux, Henri O. ; Kery, Sean M. ; Walden, Robert G.
    As part of a development effort in the field of moored arrays sponsored by the Office of Naval Technology, the Ocean Structures and Moorings Laboratory (OSM&L), Applied Ocean Physics and Engineering Department (AOP&E), Woods Hole Oceanographic Institution (WHOI) conducted a study in 1991 to assess the feasibility and the merits of several self-deployable mooring designs. This study included a brief review of the state of the art, the performance of lab tests to evaluate different mooring line payout concepts, and the preliminary design of a typical candidate mooring. The results of this study are presented in this report. The report first reviews three types of single point moored arrays which are amenable to self-deployment: subsurface, subsurface with surface expression, and surface with bottom inverted catenary. It then describes the features common to all self-deploying moorings: techniques for line and instrument storage, means for controlled payout, bottom finders and lock up mechanisms, and it also outlines desirable specifications for sensor sizes, cables and connectors. Next the report reviews typical deployment scenarios from the bottom up or from the surface down as they apply to the three types of moorings retained. In its final section, the report presents the conceptual design of a 6000 meters depth capability, bottom up deployment, candidate mooring. This configuration should be of strong interest when contemplating the deployment of a large number of identical subsurface moorings, interconnected by a bottom cable, and in "close" proximity to one another. The case study outlines the design objectives and the current profiles, specifies the main components, evaluates their performance with the help of a standard computer program, and presents packaging and payout control details. Finally, a plan is proposed for the controlled, in-situ evaluation of a prototype.
  • Technical Report
    Analysis & experimental evaluation of single point moored buoy systems
    (Woods Hole Oceanographic Institution, 1969-05) Berteaux, Henri O. ; Walden, Robert G.
    This report reviews the analysis and the evaluation of surface buoy systems performed in the Engineering Department of the Woods Hole Oceanographic Institution in 1968. The buoy systems considered are single point moored, taut and compound consisting of wire and synthetic ropes, The first part of the report describes the forcing functions and the system response as measured in situ during and after launching, The second part presents the results of the mooring line components testing and evaluation programs performed at sea or in laboratories. The third part briefly outlines the present development in telemetry transmission of scientific and engineering information, It is believed that this systematic engineering effort is an important factor in the continuous improvement of the reliability and performance of the deep sea buoy systems used in scientific measurements programs.
  • Technical Report
    A study of CTD cables and lowering systems
    (Woods Hole Oceanographic Institution, 1979-12) Berteaux, Henri O. ; Walden, Robert G. ; Moller, Donald A. ; Agrawal, Yogesh C.
    This study first reviews both the electrical and mechanical modes and causes of failure of electromechanical (E/M) cables used to lower deep sea sensors, such as CTD instruments, from oceanographic ships. It then outlines measures or steps that could be taken to correct some of the deficiencies observed and improve the systems presently used. These measures include quality control, tests, operational limits, improved handling and maintenance, improved machinery. The study then surveys alternative cables for lowering the sensors and convey the information from the sensors back to the ship. These alternatives include strength members other than steel (Kevlar)and signal carriers other than conventional copper conductors (fiber optics). The final section - Conclusions - summarizes the recommendations, based on this study, for improving the reliability of present and future CTD lowering systems.
  • Technical Report
    Design of a stable floating platform for air-sea interaction measurements
    (Woods Hole Oceanographic Institution, 1978-12) Berteaux, Henri O. ; Walden, Robert G.
    The design of an oceanographic platform can be defined as the rational specification of the platform dimensions and geometry. This specification is usually the result of an iterative process which compares the platform performance with the objectives to be reached and the logistic constraints to be met. This report describes such an exercise. The scientific objectives - measurements of heat flux at the ocean surface - are first outlined. The limits of heave and roll motion compatible with the desired measurement accuracy are then established. Given the stochastic nature of platform response, these limits are stipulated in terms of expected means. A review is then made, in some detail, of the analytical approach followed and of the computer programs used to compute the statistical expectations of buoy heave and roll response to random sea excitation. The next section of the report describes the comprehensive parametric study performed on some twenty different buoy configurations. The purpose of this study was first to investigate the dynamic response of a plausible base line design and of modified versions of the base line. A comparison of the dynamic response of these configurations could then"be made, and the good features that this comparison would reveal could be used to design the buoy prototype. Following this approach a final configuration was specified which would meet the rather severe motion requirements (0. 2 feet RMS in heave and 5. 0 degrees RMS in roll in sea state 3). The final section describes the techniques recommended to deploy and recover the 60 feet long buoy prototype.
  • Technical Report
    A feasibility study for a versatile deep sea, multileg, stable, cable array
    (Woods Hole Oceanographic Institution, 1981-03) Berteaux, Henri O. ; Walden, Robert G.
    The purpose of this study is to investigate the feasibility of designing, building, and deploying a large, stable, multileg, deep ocean cable array with a service life of at least five years, and to assess the cost of such an array. The study first defines the essential desirable features of the array. It then briefly describes a number of candidate configurations which can meet these requirements, pointing out their advantages and disadvantages. The study then undertakes an array comparative stability analysis. The Fortran computer program DESADE was used to perform this comprehensive study. Current induced displacements and stress levels of simple and complex arrays were computed using this program. The results thus obtained greatly helped quantify their relative merit . Based on this analysis and on the array requirements previously defined a candidate array is selected for preliminary design. This design essentially consists of the rational selection of type, size, and materials for the buoys, cables, and anchors of the prototype array . Safety factors compatible with the five years life expectancy arc confirmed by additional computer runs, using operational and survival current conditions. The successful deployment and practical servicing of a deep sea implanted array require careful planning and detailed preparation. The next phase of this study is to outline a deployment scenario, and to indicate the different methods for servicing the array. Power sources and methods of data retrieval are considered. Use of manned and unmanned submersibles is contemplated . The last phase of the study is an estimate of the cost of the prototype array components. The report concludes that such an array is feasible, that it can be implanted with a high expectation of reliability and that it can be a safe and stable structure from which to conduct divers novel and useful scientific experiments.
  • Technical Report
    Improvement of intermediate oceanographic winches
    (Woods Hole Oceanographic Institution, 1985-03) Berteaux, Henri O. ; Walden, Robert G. ; Bonde, Leslie W. ; Bird, J. D.
    The following is a report on the findings of a study conducted by the Woods Hole Oceanographic Institution to assess the needs and the means for improving the conventional intermediate winches used in the oceanographic community to lower profiling instruments (CTD for example). Eight major u.s. oceanographic centers were visited to confirm community needs and common problem areas, and to survey existing lowering equipment and techniques. This information was used to develop a set of general requirements for an improved instrument lowering system. Recommended improvements included: compensation of wave induced ship motion, automation of casts, and capability for automatic tracking of oceanographic parameters. A review is presented of additions or modifications which could meet these requirements. These options are compared and the system which offers the best potential for scientific usefulness, ease of fleet implementation and/or retrofitting of existing equipment is described at the conceptual and general specifications level. A plan for the design procurement, test and demonstration of a working prototype concludes the study.