Cytological Observations of the F1 and Two Backcross Generations of T.Vulgare X Agropyron Spp.

This cytological study was undertaken to (1) obtain basic knowledge of these two genera and observe the chromosome compatibility in the F1 and (2) to note the trend and the rate if return toward chromosomal stability in the subsequent backcross generations

Controlling runoff and erosion at urban construction sites (2003)

This publication discusses typical practices to reduce erosion an dretain sediment on construction sites. Erosion- and sediment-control structures should be installed and maintained in accordance with local jurisdictions, manufacturers' specifications or engineering drawings

Theoretical Chemical Dynamics Studies of Elementary Combustion Reactions

The purpose of this research was the development and application of theoretical/computational methods for accurate predictions of the rates of reactions in many-atom systems. The specific aim was to improve computational methods for studying the chemical dynamics of large, complex systems and to obtain a better understanding of the chemical reactions involving large polyatomic molecules and radicals. The focus was on the development an automatic potential energy surface generation algorithm that takes advantage of high-performance computing environments; e.g., software for rate calculations that direct quantum chemistry codes to produce ab initio predictions of reaction rates and related dynamics quantities. Specifically, we developed interpolative moving least-squares (IMLS) methods for accurately fitting ab initio energies to provide global PESs and for use in direct dynamics simulations

Transducer Radiation Modeling for Ultrasonic Inspection Purposes

One of the main goals of ultrasonic inspection is to determine the absolute scattering response from a given reflector (i.e., defect). In the literature there are a number of reported successful approaches for evaluation of the absolute scattering response from spheroidal inclusions and voids [1]. These approaches were based on a measurement model that accounts for transducer diffraction effects and the scattering and propagation through liquid-solid interfaces. Approximate analytic diffraction corrections were developed for some experimental configurations, and consequently the scattering responses were deconvolved from received ultrasonic signals in an absolute sense. However, one of the important conditions for the accuracy of the deconvolution process is the proper modeling of the individual transducer diffraction characteristic. There is evidence [2,3] based upon on-axis pressure studies and C-scan profiles that considerable discrepancies can occur between individual transducers of the same diameter and nominal frequency. The main purpose of this paper is to study the acoustic characteristics of a set of three unfocused, immersion, piezoelectric, pulse-echo transducers. The analysis of transducer modeling was performed by correlating the vibrating piston theory with experimental results

Eddy Current Detection of Subsurface Cracks in Engine Disk Boltholes

The development of a reliable eddy current inspection system to detect second layer cracks in sleeved engine disk bolt holes poses serious difficulties. This paper discusses some initial results obtained in two separate investigations that are aimed at advancing the state-of-the-art in eddy current detection of subsurface cracks. Both finite element design optimization results of a horseshoe shaped ferrite core probe, and the results of preliminary evaluation of the applicability of electric current perturbation (ECP) technique to the current problem are presented in this paper

MOSAIC: A Scalable reconfigurable 2D array system for NDT

This paper documents the development of a scalable 2D array system, or Mosaic that can be targeted at a wide range of NDT applications by way of a reconfigurable tile that can be tessellated to form arrays of any size and shape. Close coupling permits utilization of excitation voltages as low as +/-3.3V with insertion loss of 48dB on reflection from an aluminum back wall at 73mm achieved using 2D arrays without decoding