نتایج جستجو برای: ultrasonic nondestructive examinations

تعداد نتایج: 70280  

Journal: :EURASIP J. Adv. Sig. Proc. 2010
Addisson Salazar Luis Vergara

We consider a classifier based on Independent Component Analysis Mixture Modelling (ICAMM) to model the feature jointprobability density. This classifier is applied to a challenging novel application: classification of archaeological ceramics. ICAMM gathers relevant characteristics that have general interest for material classification. It can deal with arbitrary forms of the underlying probabi...

2006
Brian J. Tucker Aaron A. Diaz Brian A. Eckenrode

Government agencies and homeland security related organizations have identified the need to develop and establish a wide range of unprecedented capabilities for providing scientific and technical forensic services to investigations involving hazardous chemical, biological, and radiological materials, including extremely dangerous chemical and biological warfare agents. Pacific Northwest Nationa...

2004
X. Zhao C. Kwan K. M. Luk

A prototype wireless guided wave inspection system is developed to inspect layered structures such as aircraft wing. The system includes a stationary antenna and an active antenna as transceivers, an on-board antenna as transponder, and PVDF comb transducers for generating and receiving ultrasonic Lamb waves. Preliminary experiments on a 0.8mm aluminium plate with a 12mm long, 50% through-wall-...

2016
Alfred V. Clark R. Bruce Thompson

An indication of the formability of metallic sheet is determined using a correlation between nondestructively measurable ultrasonic properties and a formability index. A calibration relation is initially established by measuring ultrasonic velocities at various angles to the rolling direction of sheet specimens with noncontacting electromagnetic acoustic transducers, calculating an ultrasonic c...

2000
Sanli Ergun

Nondestructive evaluation techniques Amlrurn , which use conventional piezoelectric transducers tvDicallv reauire liquid coupling fluids to improve " _ . the impedance mismatch between piezoelectric materials and air. Air-coupled ultrasonic systems can eliminate this requirement if the dynamic range of the system is large enough such that the losses a t the air-solid interfaces are tolerable. C...

2004
Weibin Zhang Yong Tian Zhanfeng Yang Liling Wang

Polymer Bonded Explosives (PBX) are well-known explosives for the weapons, especially for the parts of some important weapon. Generally, they first are modelled in cylinder. One of the most important issues in PBX cylinder properties is the detection of its flaw. Each PBX cylinder may have flaws that influence the security, machine-performance and other important physical or chemical performanc...

2004
Ahmed Yamani Maamar Bettayeb Lahouari Ghouti

Pulse-echo reflection techniques are used for ultrasonic flaw detection in most commercial instruments. As the measured pulse echo signal is assumed to be the result of linearly convolving the defect impulse response (IR) with the measurement system response, the objective is thus, to remove the effect of the measurement system through a deconvolution operation and extract the defect impulse re...

2005
SAMUEL AMSTUTZ

Abstract. The aim of the topological sensitivity analysis is to determine an asymptotic expansion of a shape functional with respect to the variation of the topology of the domain. In this paper, we consider a state equation of the form div (A∇u) + ku = 0 in dimensions 2 and 3. For that problem, the topological asymptotic expansion is obtained for a large class of cost functions and two kinds o...

2010
JAEJOON KIM

The effective noise reduction schemes in ultrasonic inspection have shown significant role for detection of flaws in materials. This paper presents the comparative result of noise reducing schemes based on Hilbert-Huang transform and Wavelet transform. The basic principle of HHT scheme includes two parts which are empirical mode decomposition (EMD) algorithm and a sum of intrinsic mode function...

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