Advanced propeller research

Recent results of aerodynamic and acoustic research on both single rotation and counterrotation propellers are reviewed. Data and analytical results are presented for three propellers: SR-7A, the single rotation design used in the NASA Propfan Test Assessment (PTA) flight program; CRP-X1, the initial 5+5 Hamilton Standard counterrotating design; and F7-A7, the 8+8 counterrotating G.E. design used in the proof of concept Unducted Fan (UDF) engine. In addition to propeller efficiencies, cruise and takeoff noise, and blade pressure data, off-design phenomena involving formation of leading edge vortexes are described. Aerodynamic and acoustic computational results derived from 3-D Euler and acoustic radiation codes are presented. Research on unsteady flows which are particularly important for understanding counterrotation interaction noise, unsteady loading effects on acoustics, and flutter or forced response is described. The first results of 3-D unsteady Euler solutions are illustrated for a single rotation propeller at angle of attack and for a counterrotation propeller. Basic experimental and theoretical results from studies on the unsteady aerodynamics of oscillating cascades are outlined

A DECISION MODEL TO ASSESS CATTLE FEEDING PRICE RISK

Traditional break-even/fed cattle price projections do not provide adequate risk information to feeders, investors, lenders, and other stakeholders interested in cattle feeding decisions. The objectives of this study were two-fold: 1) develop a spreadsheet model that could estimate the net income distribution surrounding a cattle placement decision based on historical errors of futures based price forecasts, and 2) determine whether information generated from the model can be used to improve placement and marketing decisions. To accomplish objective 1, model was developed that could estimate the income distribution around a pen of cattle under a cash speculating and short hedge pricing strategy. Distribution estimates were based on 7 alternative forecast horizons and were derived from historical forecast errors. To accomplish objective 2, decision rules were developed that allow the feeder to specify the maximum probability he/she is willing to risk losing a specified level of income. These decision rules were compared to random and naive decision rules by simulating the outcomes over 168 discrete six months feeding periods between 1987 and 2000. Risk averse decision rules were successful in signaling highly unprofitable feeding periods, but also filtered out highly profitable feeding periods.Livestock Production/Industries, Marketing,

A Unified Theory of Matter Genesis: Asymmetric Freeze-In

We propose a unified theory of dark matter (DM) genesis and baryogenesis. It explains the observed link between the DM density and the baryon density, and is fully testable by a combination of collider experiments and precision tests. Our theory utilises the "thermal freeze-in" mechanism of DM production, generating particle anti-particle asymmetries in decays from visible to hidden sectors. Calculable, linked, asymmetries in baryon number and DM number are produced by the feeble interaction mediating between the two sectors, while the out-of-equilibrium condition necessary for baryogenesis is provided by the different temperatures of the visible and hidden sectors. An illustrative model is presented where the visible sector is the MSSM, with the relevant CP violation arising from phases in the gaugino and Higgsino masses, and both asymmetries are generated at temperatures of order 100 GeV. Experimental signals of this mechanism can be spectacular, including: long-lived metastable states late decaying at the LHC; apparent baryon-number or lepton-number violating signatures associated with these highly displaced vertices; EDM signals correlated with the observed decay lifetimes and within reach of planned experiments; and a prediction for the mass of the dark matter particle that is sensitive to the spectrum of the visible sector and the nature of the electroweak phase transition.Comment: LaTeX, 22 pages, 6 figure

ASSESSING THE COST OF BEEF QUALITY

The number of U.S. fed cattle marketed through a value based or grid marketing system is increasing dramatically. Most grids reward Choice or better quality grades and some pay premiums for red meat yield. The Choice-Select (C-S) price spread increased 55 percent, over $3/cwt between 1989-91 and 1999-01. However, there is a cost associated with pursuing these carcass premiums. This paper examines these tradeoffs both in the feedlot and in a retained ownership scenario. Correlations between carcass and performance traits resulted in economic tradeoffs that change across input costs and quality grade premiums and discounts. Feedlot profitability was largely determined by marbling, carcass weight, and feed efficiency. Carcass weight was most important at a low C-S spread. However, at average C-S spread and higher, marbling became the largest determinate of feedlot profits, and its importance increased with the C-S spread. Carcass weight and feed efficiency influence on feedlot profitability declined at higher C-S spreads. Rib-eye area was the fourth most important variable and declined in importance as marbling increased in importance. There is some indication that cows with lower feed costs also produce the most profitable calf for the feedlot, and vice-versa. The data suggests that cow size and marbling score are negatively correlated. The current trend toward wider C-S spreads and rewarding higher quality grading cattle places greater emphasis on marbling ability of calves. These correlations and results suggest that higher marbling is associated with lower cost cows to maintain.Livestock Production/Industries, Marketing,

Simulation at Dryden Flight Research Facility from 1957 to 1982

The Dryden Flight Research Facility has been a leader in developing simulation as an integral part of flight test research. The history of that effort is reviewed, starting in 1957 and continuing to the present time. The contributions of the major program activities conducted at Dryden during this 25-year period to the development of a simulation philosophy and capability is explained

Weight optimization of an aerobrake structural concept for a lunar transfer vehicle

An aerobrake structural concept for a lunar transfer vehicle was weight optimized through the use of the Taguchi design method, finite element analyses, and element sizing routines. Six design parameters were chosen to represent the aerobrake structural configuration. The design parameters included honeycomb core thickness, diameter-depth ratio, shape, material, number of concentric ring frames, and number of radial frames. Each parameter was assigned three levels. The aerobrake structural configuration with the minimum weight was 44 percent less than the average weight of all the remaining satisfactory experimental configurations. In addition, the results of this study have served to bolster the advocacy of the Taguchi method for aerospace vehicle design. Both reduced analysis time and an optimized design demonstrated the applicability of the Taguchi method to aerospace vehicle design

A distributed programming environment for Ada

Despite considerable commercial exploitation of fault tolerance systems, significant and difficult research problems remain in such areas as fault detection and correction. A research project is described which constructs a distributed computing test bed for loosely coupled computers. The project is constructing a tool kit to support research into distributed control algorithms, including a distributed Ada compiler, distributed debugger, test harnesses, and environment monitors. The Ada compiler is being written in Ada and will implement distributed computing at the subsystem level. The design goal is to provide a variety of control mechanics for distributed programming while retaining total transparency at the code level

A simple nonlinear model of a generic axisymmetric wave energy converter

The aim of this work is to develop a simple nonlinear model of a wave energy converter (WEC) for capturing power from ocean waves and converting it into electrical power. A generic axisymmetric device is considered, which consists of a vertical circular cylinder surrounded by a circular annulus. The nonlinear system of equations of motion of this generic WEC are derived; these include the nonlinear term arising from viscous drag due to boundary layer separation. The expressions for radiation damping and added mass are determined by dimensional analysis. These equations are then solved numerically and the results are displayed graphically in a number of figures. Consideration of these graphs leads to conclusions that should be taken into account by the design engineer