The potential use of rudders as anti-roll devices has long been recognized. However, the possible interference of this secondary function of the rudder with its primary role as the steering mechanism has prevented, fo...
The potential use of rudders as anti-roll devices has long been recognized. However, the possible interference of this secondary function of the rudder with its primary role as the steering mechanism has prevented, for many years, the development of practical rudder roll stabilizers. The practical feasibility of rudder roll stabilization has, however, in recent years been demonstrated by two systems designed and developed for operational evaluation aboard two different U.S. C oast G uard Cutters, i.e., Jarvis and Mellon of the 3,000-ton, 378-foot HAMILTON Class. The authors describe the major components of the rudder roll stabilization (RRS) system, along with the design goals and methodology as applied to these first two prototypes. In addition, a brief history of the hardware development is provided in order to show some of the lessons learned. The near flawless performance of the prototypes over the past four years of operational use in the North Pacific is documented. Results from various sea trials and reports of the ship operators are cited and discussed. The paper concludes with a discussion of the costs and benefits of roll stabilization achieved using both a modern anti-roll fin system, as well as two different performance level RRS systems. The benefits of roll stabilization are demonstrated by the relative expansion in the operational envelopes of the USS OLIVER HAZARD PERRY (FFG-7) Class. The varying levels of roll stabilization suggest that the merits of fins and RRS systems are strongly dependent on mission requirements and the environment. The demonstrated performance of the reliable RRS system offers the naval ship acquisition manager a good economical stabilization system.
The influence of aerobic swin conditioning on levels of maternal physical fitness and the influence of each swim bout on selected maternal and fetal circulatory parameters were investigated. Thirteen women who met cri...
The influence of aerobic swin conditioning on levels of maternal physical fitness and the influence of each swim bout on selected maternal and fetal circulatory parameters were investigated. Thirteen women who met criteria for a low-risk homogeneous sample were randomly assigned to either an experimental (n = 7) or a control (n = 6) group. Experimental subjects participated in ten weeks of a swim conditioning program, while control subjects maintained their normal activities (to exclude aerobic conditioning). Fitness levels for all subjects were determined from respiratory gas analysis during graded exercise testing on a treadmill prior to and following the swim conditioning program. Testing indicated that experimental subjects were able to maintain their initial fitness levels over the twelve weeks of increasing gestation, while control subjects were not able to do so. These findings suggest the effectiveness of the swim conditioning program in countering a potential decrease in fitness levels. Importantly, maternal blood pressure, pulse, and fetal heart rate response remained within clinically normal limits during swim conditioning for experimental subjects, and during treadmill testing for all subjects.
作者：
LARSON, NORMAN O.DEMYTTENAERE, JULES H.OREM, JOHN B.Commander Norman O. Larson
USN: is an Engineering Duty Officer of the United States Navy who served in the Army as a sergeant of infantry in Europe during World War II. Appointed to the U. S. Naval Academy in 1945 he graduated in June 1949. After two years in the Amphibious Force U. S. Pacific Fleet on board the USS MOUNT McKINLEY (AGC-7) and one year on the USS BREMERTON (CA-130) during the Korean hostilities he attended Webb Institute of Naval Architecture. Receiving his Master of Science in Naval Architecture in 1955 he served two years as an Assistant Planning and Estimating Superintendent for Fitting Out and New Construction at Boston Naval Shipyard and then two years as Assistant Force Maintenance Officer on the staff of Commander Amphibious Force U. S. Pacific Fleet. From 1959–1961 he attended the University of California Berkeley for advanced work in Hydrodynamics. The next two years were spent at the David Taylor Model Basin as Propeller Program Officer. He has been a Project Coordinator in the Hull Design Branch Ship Design Division in the Bureau of Ships since August 1963. Commander J. H. Demyttenaere
U. S. Navy: is an Engineering Duty Officer of the United States Navy and is currently serving as a Project Coordinator in the Hull Design Branch of the Ship Design Division in the Bureau of Ships. He received his B.S. degree in Engineering from the U. S. Naval Academy in 1949. After serving a two year tour on board the USS PHILIPPINE SEA (CV-47) he was ordered to postgraduate training and received the degree of Naval Engineer from the Massachusetts Institute of Technology in 1954. He has served in numerous Engineering Duty Officer billets since 1954 including two years at Philadelphia Naval Shipyard in the Production Department two years of Staff Duty with Commander Service Squadron One three years as Design Project Officer at Supervisor of Shipbuilding New York and most recently as Repair Officer in USS ARCADIA (AD-23). Lieutenant Commander John B. Orem
Jr. USN: is an Engineering Dut
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