Investigation of ground reflection and impedance from flyover noise measurements

An extensive series of flyover noise tests was conducted for the primary purpose of studying meteorological effects on propagation of aircraft noise. The test airplane, a DC 9-10, flew several level-flight passes at various heights over a taxiway. Two microphone stations were located under the flight path. A total of 37 runs was selected for analysis and processed to obtain a consistant set of 1/3 octave band sound pressure levels at half-second intervals. The goal of the present study was to use the flyover noise data to deduce acoustical reflection coefficients and hence, acoustical impedances

Sub-femtosecond electron bunches created by direct laser acceleration in a laser wakefield accelerator with ionization injection

In this work, we will show through three-dimensional particle-in-cell simulations that direct laser acceleration in laser a wakefield accelerator can generate sub-femtosecond electron bunches. Two simulations were done with two laser pulse durations, such that the shortest laser pulse occupies only a fraction of the first bubble, whereas the longer pulse fills the entire first bubble. In the latter case, as the trapped electrons moved forward and interacted with the high intensity region of the laser pulse, micro-bunching occurred naturally, producing 0.5 fs electron bunches. This is not observed in the short pulse simulation.Comment: AAC 201

ECONOMIC THRESHOLDS: AN APPLICATION TO FLORICULTURE

This paper introduces conjunctive optimal pest management and production decision rules applied to the floriculture industry. A grower is faced with optimally controlling multiple pests and applying cultural controls to maximize the expected net present value of benefits within a discrete time framework, subject to biological and marketing constraints.Crop Production/Industries,

OPTIMAL PEST CONTROL IN FLORICULTURE PRODUCTION OF ORNAMENTAL CROPS

We develop a conceptual bioeconomic model of floriculture production, wherein optimal decision rules depend on an intertemporal economic objective to maximize profits subject to economic and biological processes. The necessary conditions highlight intertemporal tradeoffs between aesthetic benefits and expected future net benefits of insect stocks, which have important policy implications.Research Methods/ Statistical Methods,

Input inefficiency in commercial banks: a normalized quadratic input distance approach

A normalized quadratic input distance function is proposed with which to estimate technical efficiency on commercial banks regulated by the Federal Reserve System. The study period covers 1990 to 2000 using individual bank information from the Call and Banking Holding Company Database. A stochastic frontier model is specified to estimate the input normalized distance function and obtain measures of technical efficiency.Banks and banking

Ground-runup tests of acoustically treated inlets and fan ducts

Ground performance tests on noise intensity of turbofan engine ducts modified by acoustic lining

Political allocation of U.S. agriculture disaster payments in the 1990s

Legislation passed during the 1990s attempted to move U.S. agriculture disaster relief to a more market oriented process. The failure of this legislation has been attributed to the political system behind agricultural disaster relief. This paper explores the impact of political influence on the allocation of U.S. direct agriculture disaster payments. The results reveal that disaster payments are not based solely on need, but are higher in those states represented by public officials key to the allocation of relief. The effectiveness of legislation aimed at promoting more efficient disaster payments systems, such as crop insurance, over direct cash payments is also examined.Agriculture ; Disaster relief

PREDICTING HOUSEHOLD WATER CONSUMPTION UNDER A BLOCK PRICE STRUCTURE

This study focuses on estimating the variations in per-capita water consumption and predicting the shares of consumption by pricing blocks in eight Kansas regions. Previous studies have considered household or micro-level consumption, but few have focused on aggregate level consumption across different regions. A probit model was used to estimate the consumption shares in individual blocks for each region. Per-capita water consumption varies significantly across the regions and as we move from Western to Eastern Kansas, shares of lower consumption block decrease and higher consumption block likely to increase.Resource /Energy Economics and Policy,

Orbital periods of the binary sdB stars PG0940+068 and PG1247+554

We have used the radial velocity variations of two sdB stars previously reported to be binaries to establish their orbital periods. They are PG0940+068, (P=8.33d) and PG1247+554 (P=0.599d). The minimum masses of the unseen companions, assuming a mass of 0.5 solar masses for the sdB stars, are 0.090 +/- 0.003 solar masses for PG1247+554 and 0.63 +/- 0.02 solar masses for PG0940+068. The nature of the companions is not constrained further by our data.Comment: 5 pages, 2 figure

WHOLESALE DEMAND FOR USDA QUALITY GRADED BOXED BEEF AND EFFECTS OF SEASONALITY

This study estimates wholesale demand for pork, chicken, and quality differentiated beef. We estimate meat retailer own- and cross-price demand elasticities for USDA Choice and Select boxed beef. Results indicate that meat retailers have more elastic demand for lower quality graded beef. Retail beef price has a strong positive relationship with Choice and Select boxed beef demand, and a strong negative relationship with wholesale pork and chicken demand. Seasonal analysis reveals demand for both beef quality grades becomes highly price inelastic during the summer months. The two beef quality grades are substitutes during the winter; however, Select beef is not a substitute for Choice beef in the spring and summer.Demand and Price Analysis,