Variable camber rotor study

Deployment of variable camber concepts on helicopter rotors was analytically assessed. It was determined that variable camber extended the operating range of helicopters provided that the correct compromise can be obtained between performance/loads gains and mechanical complexity. A number of variable camber concepts were reviewed on a two dimensional basis to determine the usefulness of leading edge, trailing edge and overall camber variation schemes. The most powerful method to vary camber was through the trailing edge flaps undergoing relatively small motions (-5 deg to +15 deg). The aerodynamic characteristics of the NASA/Ames A-1 airfoil with 35% and 50% plain trailing edge flaps were determined by means of current subcritical and transonic airfoil design methods and used by rotor performance and loads analysis codes. The most promising variable camber schedule reviewed was a configuration with a 35% plain flap deployment in an on/off mode near the tip of a blade. Preliminary results show approximately 11% reduction in power is possible at 192 knots and a rotor thrust coefficient of 0.09. The potential demonstrated indicates a significant potential for expanding the operating envelope of the helicopter. Further investigation into improving the power saving and defining the improvement in the operational envelope of the helicopter is recommended

Trapping Oyster Drills In Virginia II. The time factor in relation to the catch per trap

In using traps to remove drills from oyster ground, assuming that trapping is an effective method of reducing the activities of these pests, it is important to keep costs at a minimum. One way of reducing the cost of trapping is to increase the time interval between lifts, but if the efficiency of traps varies with time, the nature of this relationship should be considered in choosing the optimum fishing interval. The influence of time on the catch must also be known to determine the significance of the catch per trap in drill trapping experiments. Dr. Andrews, in the first paper of this series, used the catch per 100 traps per day as an index of availability. Are these indices comparable when the period between lifts of the traps varies, as it sometimes did on account of bad weather or for other reasons

The pound-net fishery in Virginia. Part 2. Species composition of landings reported as menhaden

Pound nets have been the most important fishing gear for food fishes in Virginia waters of Chesapeake Bay since 1880 (Reid 1955) and the history of this fishery to a great extent reflects the varying fortunes of the fisheries of that State. Since 1929 the average annual catch in pound nets in Virginia has been about 50 million pounds, roughly 20 percent of which was reported as menhaden. Actually these menhaden include varyint?: quantities of other fish species, sometimes predominantly young food fishes, too small to market as human food. This part of the pound-net catch is sometimes used as industrial fish, but in many parts of the Bay it is sold as bait for crab pots. It is commonly referred to as scrap fish, and for convenience this term has been used here to denote that part of the pound-net catch not sold for human consumption. Concern has been expressed at various times that this harvest of small fishes is wasteful, yet no really effective action has been taken to determine the facts needed for an intelligent appreciation of the situation. Reid (1955) has reviewed the tribulations that accompanied introduction of pound nets to Virginia waters. Early reports of the Virginia Commission of Fisheries emphasize the destruction caused by these nets, and in 1914 a cull law was enacted designating minimum sizes of fishes that may be caught (Code of Virginia, Section 28-45). It soon became apparent that the value of this law was limited, for most undersized fish were dead before culling could be done, and it was suggested on various occasions that an increase in mesh size, or closed seasons at certain times, would offer more practical solutions

Trapping Oyster Drills In Virginia III. The Catch Per Trap In Relation To Condition Of Bait

In the course of trapping experiments previously described (Andrews 1955, McHugh 1955), a question arose concerning deterioration of bait with time. It is fairly obvious to those who fish the traps that the condition of the bait changes. The smallest oysters die first, through predation by drills, crabs, and other enemies, and through smothering in the muddy bottom. Barnacles and other organisms on the shells also die from various causes. The valves of the dead oysters soon separate, and some are lost through meshes of the trap, so that the volume of bait also decreases. Stauber (1943) found that efficiency of traps decreased as the interval between lifts increased, He found. also that the catch increased significantly after rebaiting. A series of 20 traps was fished from the Virginia Fisheries Laboratory pier from July 1953 to December 1955. Although the traps were not rebaited until early October 1954, the catch per trap was greater during the second summer. If bait does deteriorate, as Stauber (1943) and others have concluded, this increased catch must reflect an increase in abundance or availability of Urosalpinx in 1954. But by October 1954, the bait consisted mainly of isolated valves, and the · few surviving oysters were thick-shelled and blunt. It was decided to conduct a controlled experiment with these traps to test the effect of rebaiting. This.experiment began in October i954 and continued through the summer of 1955

The Virginia Fisheries Laboratory

Reprint from the December issue of The Commonwealth, published by the Virginia State Chamber of Commerce. No date, circa 1951-52. Identified individuals and items in photos: J.L. McHugh, J.D. Andrews, Frank Carey, H.N. McCutcheon, E.C.Ladd, W.A.Van Engel, Robert S. Bailey, R/V Virginia Lee, public exhibit room, students in laboratory

Entanglement, purity and energy: Two qubits vs Two modes

We study the relationship between the entanglement, mixedness and energy of two-qubit and two-mode Gaussian quantum states. We parametrize the set of allowed states of these two fundamentally different physical systems using measures of entanglement, mixedness and energy that allow us to compare and contrast the two systems using a phase diagram. This phase diagram enables one to clearly identify not only the physically allowed states, but the set of states connected under an arbitrary quantum operation. We pay particular attention to the maximally entangled mixed states (MEMS) of each system. Following this we investigate how efficiently one may transfer entanglement from two-mode to two-qubit states.Comment: 13 figures. References and 1 figure adde

The Survival And Growth Of South Carolina Seed Oysters In Virginia Waters

Most of the seed oysters planted on private grounds along the Atlantic Coast of the United States are obtained from public seed beds. The supply depends largely upon a wild crop over which there is little control. It is to be expected, perhaps, that the quantity of seed available at various localities along the coast is in proportion to the duration of the warm season. It follows that oystermen are usually searching southward for their supply of seed and the ramifications of this hunt are complex and ever changing

History of Virginia\u27s Commercial Fisheries: neglected historical records throw light on today\u27s problems

As the Susan Constant, the Godspeed, and the Discovery made their way through Hampton Roads and up the James River toward Jarnestown in 1607, they traversed a 15-mile stretch of water that was to play an important part in the history and economy of Virginia. Beneath these pleasant waters, and sometimes forming reefs that were awash at low tide, lay the most prolific natural oyster beds in the world. Three hundred and fiftv years later these grounds still provide the seed that makes Virginia\u27s oyster industry supreme, producing about one-quarter of the nation\u27s supply of these delicious mollusks. Had they been free to harvest at will the oysters and other seafoods that were so abundant round these shores, the colonists might have escaped some of the dietary troubles that contributed to their hardships. But ignorance, lack of self-interest, and other things conspired to deny these benefits to them. Today, though ignorance and self-interest still hamper the full utilization and management of these resources, we can see ever-increasing improvement. Despite dire predictions to the contrary, these resources have continued to renew themselves, and there is no reason why they should not do so forever if exploited wisely

Autoantibodies in connective tissuedisease

Autoimmune connective tissue diseases are heterogeneous rheumatic diseases with the potential to affect multiple body systems. Autoantibodies are a characteristic feature of these diseases and are typically highly disease specific. In addition to aiding diagnosis, many autoantibodies have established associations with clinically important disease complications including internal organ involvement. In this chapter, we review the autoantibodies relevant to autoimmune connective tissue diseases, excluding systemic lupus erythematosus, with particular reference to the associated clinical features and how identification of such an autoantibody may inform prognosis and clinical management. We also discuss the practicalities of testing for autoantibodies along with potential difficulties and pitfalls.</p