432 research outputs found
Scene analysis in the natural environment
The problem of scene analysis has been studied in a number of different fields over the past decades. These studies have led to a number of important insights into problems of scene analysis, but not all of these insights are widely appreciated. Despite this progress, there are also critical shortcomings in current approaches that hinder further progress. Here we take the view that scene analysis is a universal problem solved by all animals, and that we can gain new insight by studying the problems that animals face in complex natural environments. In particular, the jumping spider, songbird, echolocating bat, and electric fish, all exhibit behaviors that require robust solutions to scene analysis problems encountered in the natural environment. By examining the behaviors of these seemingly disparate animals, we emerge with a framework for studying analysis comprising four essential properties: 1) the ability to solve ill-posed problems, 2) the ability to integrate and store information across time and modality, 3) efficient recovery and representation of 3D scene structure, and 4) the use of optimal motor actions for acquiring information to progress towards behavioral goals
Advanced Sensing, Fault Diagnostics, and Structural Health Management
Advanced sensing, fault diagnosis, and structural health management are important parts of the maintenance strategy of modern industries. With the advancement of science and technology, modern structural and mechanical systems are becoming more and more complex. Due to the continuous nature of operation and utilization, modern systems are heavily susceptible to faults. Hence, the operational reliability and safety of the systems can be greatly enhanced by using the multifaced strategy of designing novel sensing technologies and advanced intelligent algorithms and constructing modern data acquisition systems and structural health monitoring techniques. As a result, this research domain has been receiving a significant amount of attention from researchers in recent years. Furthermore, the research findings have been successfully applied in a wide range of fields such as aerospace, manufacturing, transportation and processes
Investigation of a piezo-polymer array transducer for pulse-echo ultrasonic material examinations
The aim of this investigation was to make a flexible array of
pulse-echo ultrasound transducers by etching two orthogonal linear
arrays of conducting elements into the metallisation of either side of
a sheet of PVdF. These would then be multiplexed under computer
control in an X-Y raster, thereby forming an image of subsurface
defects in a material specimen.
A potential source model was used to predict the sensitivity
of a single element air-backed transducer far from resonance. Initial
investigations confirmed the predictions, and reaffirmed the results
of previous workers.
In making a prototype array, it was found necessary to use a
bi-laminar arrangement with a central ground plane, due to
difficulties with crosstalk and charge leakage into the specimen
materials. The radiation pattern of this array was tested and found
to agree with the predictions for Fraunhofer (Far-Field) radiation.
A 10 MHz analogue to digital converter was constructed to
interface with the IBM-PC clone as a transient recorder, through a
data capture program written in 'C'. However, the electrical noise
generated by the PC was found to interfere strongly with the signal
from the array transducer.
A wide-band amplifier and full-wave rectifier was then added
to the multiplexer and A/D converter, and the system enclosed in an
electrically isolated environment, which made it possible to obtain
clear signal data from the transducer.
Non-linear regression was implemented in the software, to
smooth the data and locate echo peaks, and the most frequently
occurring peak separation was used to indicate sample thickness at
that location in a false-colour mapping on the screen of the PC
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