Application of Ultrasonic Pod Models

The ability to quantify the reliability of nondestructive evaluation (NDE) inspection techniques is required to integrate inspectability into the component design process. Inspectability is typically evaluated on the basis of the design engineer’s experience and knowledge of NDE. While this approach can yield adequate designs with regard to inspection reliability, the potential for uninspectability remains. There is also the possibility that the designer’s knowledge of the reliability of NDE techniques may be limited to “standard” approaches which may be be inadequate for new component geometries or materials. This could lead the design engineer to imagine that a given component is inadequately inspectable and to redesign the part when the correct solution is either to modify the inspection protocol or to select a different technique. Alternatively, models which predict inspection reliability could be used to weigh the trade-offs and risks associated with selection among candidate NDE techniques to be applied to inspection of a given component design and to identify NDE system configurations for optimal reliability. This approach is, in fact, a key feature of the Unified Life Cycle Engineering concept currently being developed by the Air Force[l]

Ultrasonic 3-D Reconstruction of Inclusions in Solids Using the Inverse Born Algorithm

Considerable progress has been made in recent years in the development of signal processing algorithms for use in ultrasonic non-destructive evaluation which yield the size, shape, and orientation of a flaw. This kind of flaw information is necessary in order that failure predictions of materials and components can be made from non-destructive tests. The signal processing algorithms that have been developed for ultrasonics are based upon both direct and inverse approximate solutions to the elastic wave scattering problem, and cover various ranges of the parameter ka where k=2π/λ is the wave number of the ultrasound and a is a flaw size dimension. In order to use these algorithms effectively in the determination of flaw parameters, it has been found necessary to obtain measurements of the flaw at several viewing angles. At this time, there is no ultrasonic transducer available which permits this to be done efficiently and conveniently in the long and intermediate wavelength end of the spectrum. This region has been shown to be quite rich in flaw information and is appropriate to ultrasonic NDE in many practical applications (e.g., thick wall sections).</p

Prospects for a Statistical Theory of LC/TOFMS Data

The critical importance of employing sound statistical arguments when seeking to draw inferences from inexact measurements is well-established throughout the sciences. Yet fundamental statistical methods such as hypothesis testing can currently be applied to only a small subset of the data analytical problems encountered in LC/MS experiments. The means of inference that are more generally employed are based on a variety of heuristic techniques and a largely qualitative understanding of their behavior. In this article, we attempt to move towards a more formalized approach to the analysis of LC/TOFMS data by establishing some of the core concepts required for a detailed mathematical description of the data. Using arguments that are based on the fundamental workings of the instrument, we derive and validate a probability distribution that approximates that of the empirically obtained data and on the basis of which formal statistical tests can be constructed. Unlike many existing statistical models for MS data, the one presented here aims for rigor rather than generality. Consequently, the model is closely tailored to a particular type of TOF mass spectrometer although the general approach carries over to other instrument designs. Looking ahead, we argue that further improvements in our ability to characterize the data mathematically could enable us to address a wide range of data analytical problems in a statistically rigorous manner

Technique for Generation of Unipolar Ultrasonic Pulses

Substantial progress has been made in recent years in the development of inverse elastic wave scattering theories for use in ultrasonic nondestructive evaluation (NDE). These include theories that are applicable in different ultrasonic frequency ranges and include formulations in various approximations [1–15]. It is by application of these inverse scattering solutions to ultrasonic inspection results that quantitative measures of the size, shape, and orientation of a flaw can be determined

Use of Models to Predict Ultrasonic NDE Reliability

The need to quantify and predict the probability of detection (POD) of defects by ultrasonic nondestructive evaluation (NDE) techniques is driven by the growing importance of damage tolerant design and maintenance philosophies. Experimental demonstration programs, while costly, are useful in assessing NDE system reliability for existent inspection hardware and for “typical” test specimens. However, such an approach is not effective for prediction of optimal inspection protocols nor for improving the inspectability of components at the design stage. There is, thus, a need for computationally efficient analytical models for such applications.</p

Localized orbital amyloidosis involving the lacrimal sac and nasolacrimal duct

Purpose: To report the case of a 70-year-old man who presented with tearing in his left eye and a firm palpable lump in the area overlying his left lacrimal sac. Design: Retrospective interventional case report. Methods: Noninvasive diagnostic evaluation followed by external dacryocystorhinostomy, histopathologic studies, and systemic evaluation. Results: The patient was found to have idiopathic localized amyloidosis limited to the lacrimal sac and nasolacrimal duct. Conclusion: The localized form of amyloidosis is rare, typically involves the head and neck without systemic manifestations, and carries an excellent prognosis. Previous reports of orbital amyloidosis have described involvement of the lacrimal gland, extraocular muscles, and the cranial nerves. To our knowledge, this is the first report of a patient with nasolacrimal duct obstruction secondary to amyloid deposition in the lacrimal sac and fossa. © 2006 by the American Academy of Ophthalmology.link_to_subscribed_fulltex

Finding Linear Motif Pair from Protein Interaction Networks: A Probabilistic Approach

To exploit theoretical advances in elastic wave inverse scattering, an automated multiviewing ultrasonic transducer system and the associated signal processing algorithms have been developed at the Ames Laboratory for the reconstruction of the size, shape, and orientation of volumetric flaws [1]. The flaw sizing algorithm is based on elastic wave inverse scattering theories in the long and intermediate wavelength, regime [2,3] and the three-dimensional reconstruction algorithm finds the equivalent ellipsoid that best fits the flaw sizes in the various viewing directions [4,5]. The original multiprobe system consists of six peripheral transducers equally spaced in a circle surrounding one transducer at the center. The peripheral transducers may be tilted at an angle toward the center to increase the aperture and can also be translated along their respective axes to allow an equilization of the acoustic propagation time. The axis of the aperture cone is normally placed perpendicular to the part surface. The flaw sizing procedure was a one-dimensional inverse Born algorithm to determine the flaw’s centroid-to-tangent plane distances for a number (normally 13 or 19) of pulse-echo or pitch-catch scattering directions within a finite aperture cone. The flaw sizes are then used as inputs to a nonlinear least squares regression program to yield a complete geometric reconstruction in the form of three semi-axes and three Euler angles of the best-fit ellipsoid. Using this system, successful reconstructions have been obtained for both oblate spheroidal (disk-like) and prolate spheroidal (rod-like) inclusions and voids. The readers are referred to a complete description of the system in Ref. 1