Optimization of Electromagnetic Transducer Systems

Electromagnetic transducers have a number of inherent advantages, some of which have been touched on by other speakers. Historically, their major disadvantage has been their high insertion loss. We have undertaken a project which has been designed to explore techniques for optimizing transducer efficiencies and increasing the dynamic response of ultrasonic systems which use electromagnetic transducers. Today, we would like to report the results of that project

UTSim: overview and application

UTSim is a software package developed to help plan and refine ultrasonic inspections for complex shaped components. The software reads 3D solid‐model CAD representations of the components. Virtually any shape or complexity of object can be loaded and examined using the ultrasonic ray tracing tools in UTSim. For many applications, the software can also be used to model ultrasonic beam propagation as well as the response from flaws within a component. This presentation will give an overview of UTSim and its features and will demonstrate examples of its ultrasonic simulation capabilities

Metal inventory and fate of suspended sediment in Chesapeake Bay

This report aims to provide new information that meets selected objectives of the EPA-States Taxies Plan of Action: i.e. (1) to determine the state of the Bay with respect to the distribution and concentration of selected metals in suspended material and fluid mud; (2) to establish the temooral variations of sediment and metal loading: (3) to identify potential zones of metal accumulation and trace their transport routes, and (4) to provide recommendations for monitoring contaminated sediment. Field observations provide longitudinal coverage of the Bay with transects into Baltimore Harbor and Hampton Roads. They include contrasting conditions of seasonal high-low river discharge and sediment influx, as well as neap-spring tide range and oxygenated-anoxic water. Suspended material collected on Nuclepore filters, was analyzed by flame AA for Fe, Mn and Zn and by flameless .\u27A.A for As, Cd, Cu, Hg, Ni, Pb and Sn. Laboratory procedures followed EPA quality control standards using USGS Standards. The survey occupied 122 stations, accomplished 5,576 measurements including 633 analyses of 6 to 11 metals in suspended material and fluid mud. Physical, chemical and sedimentological conditions for transport and accumulation of taxies in the Bay are variable with time and distance seaward. Bay water is partly-mixed, well-buffered against pH change and well-oxygenated except in summer when near·-bottom water of the axial basin is anoxic. Salinity and sediment influx vary seasonally with river discharge and form steep seaward gradients near the inner limit of salty water. Characteristics of suspended material define three broad zones: (1) the turbidity maximum (stations 12-18) with high suspended loads, fine particle size and low organic percentages: (2) the central Bay (stations 8-11) with low suspended loads, coarse particle size and high organic percentages; (3) the near-entrance reaches (stations 1-7) with intermediate suspended loads, moderate particle size and organic percentages. Sediment in deeper parts of the central Bay is fine-grained, moderately organic and depositing relatively fast.. These conditions favor accumulation of metals and fluid mud

Response and Recovery to Sediment Influx in the Rappahannock Estuary: A Summary

Flooding from Tropical Stonn Agnes produced unique hydrographic conditions for transport and dispersal of sediment in the Rappahannock and .James estuaries. Analyses indicate two cycles of response and recovery to the shock of extreme freshwater and sediment influx; one cycle in response to Rappahannock inflow; the other to intense mixing within the estuary. Important stages in the sequence consist of: (1) an initial response and seaward surge of river water and sediment; (2) shock with downstream translation of the salt intrusion head with a near-bottom salinity front and high turbidity in surface and in bottom water; (3) rebound with intense stratification and formation of an enriched turbidity maximum; (4) partial recovery with salinity intrusion strengthened by upstream flow along the bottom; landward migration of the maximum; (5) full recovery and return to partly-mixed state with decay of turbidity maximum over a broad zone 30 days after flooding. Sediment was derived initially from lateral tributaries and then from the main river. The bulk of the load sedimented above the salt intrusion during the first three days of flooding. Sediment dispersed into the estuarine circulation system later was effectively trapped by upstream flow along the bottom. Over the entire event, 91% of the sediment load was trapped.https://scholarworks.wm.edu/vimsbooks/1066/thumbnail.jp

The Middle Ground of the NDE R&D Spectrum

Our keynote talk today has several objectives: First, we want to call attention, as some of us have before, to the interdisciplinary nature of NDE science and technology and some approaches for fostering R&D in such a situation. Next, we want to describe the objective of the DARPA, Air Force (and now Navy) core program for developing a science base for NDE and how it has evolved during the past two years. Some changes have indeed taken place; we feel that they were both necessary and evolutionary. Many of you are probably familiar with these changes by now but there may be some residual concerns or questions in your minds. Since I was the initiating influence behind most of them, it is appropriate for you to hear me say what they are and what they aren’t, and to have an opportunity to question us. Finally and most importantly, we want to enlist your participation in the difficult task of identifying exploratory development programs—and we will try to define this term—which will benefit from the growing science base that all of us are helping to develop. We hope to stimulate the interaction between people such as you and the consumers of the evolving NDE technology in order to identify reduction-to-practice possibilities that should be pursued

Impaired Spatial Reorientation in the 3xTg-AD Mouse Model of Alzheimer's Disease.

In early Alzheimer's disease (AD) spatial navigation is impaired; however, the precise cause of this impairment is unclear. Recent evidence suggests that getting lost is one of the first impairments to emerge in AD. It is possible that getting lost represents a failure to use distal cues to get oriented in space. Therefore, we set out to look for impaired use of distal cues for spatial orientation in a mouse model of amyloidosis (3xTg-AD). To do this, we trained mice to shuttle to the end of a track and back to an enclosed start box to receive a water reward. Then, mice were trained to stop in an unmarked reward zone to receive a brain stimulation reward. The time required to remain in the zone for a reward was increased across training, and the track was positioned in a random start location for each trial. We found that 6-month female, but not 3-month female, 6-month male, or 12-month male, 3xTg-AD mice were impaired. 6-month male and female mice had only intracellular pathology and male mice had less pathology, particularly in the dorsal hippocampus. Thus, AD may cause spatial disorientation as a result of impaired use of landmarks

Ultrasonic NDE of thick composites

A series of ultrasonic techniques being developed for the characterization of thick composites are described. Techniques for the in-situ measurements of elastic constants on thick-walled cylinders based on the times of a variety of ultrasonic modes of propagation are first presented, followed by discussion of the determination of the porosity from measurements of the frequency dependence of the attenuation. Two techniques for imaging delamination are then discussed. The first involves inferring size from plots of reflected signal amplitude versus lateral position of the transducer with a model for beam propagation in anisotropic media used to deconvolve the effects of the distant and direction dependent beam width. The second makes use of synthetic aperture techniques

Sensitivity Analysis of the Ultrasonic Response from a Non-Normal Surface-Breaking Crack

The use of computer simulations is becoming an increasing popular strategy for designing ultrasonic inspections. There are many benefits of accurate simulations, the most important one being their cost effectiveness. In many cases, before inspection procedures are finalized, it is possible to simulate the competing inspection plans, and to use the outputs of simulation trials to choose the best plan. This strategy is particularly useful when there is limited accessibility to the components that need to be inspected, as in the extreme case when the inspection procedure requires that operating equipment be removed from service. In such cases, it is best to be fully prepared before taking the inspection equipment to the test site and computer simulations can play an important role in such preparation, often at a significantly reduced cost with respect to traditional methods