Measurement of thin films using very long acoustic wavelengths

A procedure for measuring material thickness by means of necessarily-long acoustic wavelengths is examined. The approach utilizes a temporal phase lag caused by the impulse time of wave momentum transferred through a thin layer that is much denser than its surrounding medium. In air, it is predicted that solid or liquid layers below approximately 1/2000 of the acoustic wavelength will exhibit a phase shift with an arctangent functional dependence on thickness and layer density. The effect is verified for thin films on the scale of 10 microns using audible frequency sound (7 kHz). Soap films as thin as 100 nm are then measured using 40 kHz air ultrasound. The method's potential for imaging applications is demonstrated by combining the approach with near-field holography, resulting in reconstructions with sub-wavelength resolution in both the depth and lateral directions. Potential implications at very high and very low acoustic frequencies are discussed.Comment: Submitted to Journal of Applied Physic

Friction measuring apparatus Patent

Kinetic and static friction force measurement between magnetic tape and magnetic head surface

Price Effects from an Anticipated Meatpacking Plant Opening and Unexpected Plant Closing

Livestock producers primarily, but policy makers also, have an interest in market effects from meatpacking plant closings and openings. This article presents results from a study to determine price impacts from an anticipated hog slaughtering plant opening and an unexpected fed cattle slaughtering plant closing. The estimated price effects for each plant event were modeled with price difference and partial adjustment models. The plant opening resulted in higher absolute and relative hog prices in the Provincial market where the plant was located. However, adverse price impacts from the fed cattle plant closing were less evident.buyer competition, fed cattle, hogs, livestock prices, market dynamics, meatpacking, Demand and Price Analysis,

A k-space method for nonlinear wave propagation

A k-space method for nonlinear wave propagation in absorptive media is presented. The Westervelt equation is first transferred into k-space via Fourier transformation, and is solved by a modified wave-vector time-domain scheme [Mast et al., IEEE Tran. Ultrason. Ferroelectr. Freq. Control 48, 341-354 (2001)]. The present approach is not limited to forward propagation or parabolic approximation. One- and two-dimensional problems are investigated to verify the method by comparing results to the finite element method. It is found that, in order to obtain accurate results in homogeneous media, the grid size can be as little as two points per wavelength, and for a moderately nonlinear problem, the Courant-Friedrichs-Lewy number can be as small as 0.4. As a result, the k-space method for nonlinear wave propagation is shown here to be computationally more efficient than the conventional finite element method or finite-difference time-domain method for the conditions studied here. However, although the present method is highly accurate for weakly inhomogeneous media, it is found to be less accurate for strongly inhomogeneous media. A possible remedy to this limitation is discussed

CAPTIVE SUPPLY TRENDS AND IMPACTS SINCE THE ADVENT OF MANDATORY PRICE REPORTING

Captive supplies have been a contentious issue in the livestock industry for fifteen years and the subject of both theoretical and empirical research. In 2001, mandatory price reporting was implemented. One objective by its proponents was to increase the amount of information available on captive supplies. This paper examines data now available as a result of mandatory price reporting to determine what additional information is available compared to previously. Second, several models were specified and estimated to determine the impacts captive supplies had on fed cattle prices in the two years following implementation of mandatory price reporting. Models showed mixed results. There was a consistent negative effect on cash market prices from formula priced trades; generally a positive impact from negotiated trades and packer owned trades on cash market prices; and mixed but often a positive impact from forward contract trades on cash market prices.Livestock Production/Industries, Marketing,

A theory of human error

Human errors tend to be treated in terms of clinical and anecdotal descriptions, from which remedial measures are difficult to derive. Correction of the sources of human error requires an attempt to reconstruct underlying and contributing causes of error from the circumstantial causes cited in official investigative reports. A comprehensive analytical theory of the cause-effect relationships governing propagation of human error is indispensable to a reconstruction of the underlying and contributing causes. A validated analytical theory of the input-output behavior of human operators involving manual control, communication, supervisory, and monitoring tasks which are relevant to aviation, maritime, automotive, and process control operations is highlighted. This theory of behavior, both appropriate and inappropriate, provides an insightful basis for investigating, classifying, and quantifying the needed cause-effect relationships governing propagation of human error

Examination of the Nature of the ABC Effect

Recently it has been shown by exclusive and kinematically complete experiments that the appearance of a narrow resonance structure in double-pionic fusion reactions is strictly correlated with the appearance of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. Whereas the resonance structure got its explanation by the $d^*(2380)$ dibaryonic resonance, a satisfactory explanation for the ABC effect is still pending. In this paper we discuss possible explanations of the ABC effect and their consequences for the internal structure of the $d^*$ dibaryon