Periodic Plus Smooth Image Decomposition

When the Discrete Fourier Transform of an image is computed, the image is implicitly assumed to be periodic. Since there is no reason for opposite borders to be alike, the “periodic” image generally presents strong discontinuities across the frame border. These edge effects cause several artifacts in the Fourier Transform, in particular a well-known “cross” structure made of high energy coefficients along the axes, which can have strong consequences on image processing or image analysis techniques based on the image spectrum (including interpolation, texture analysis, image quality assessment, etc.). In this paper, we show that an image can be decomposed into a sum of a “periodic component” and a “smooth component”, which brings a simple and computationally efficient answer to this problem. We discuss the interest of such a decomposition on several applications.     

Estimation and forecasting of machine health condition using ARMA/GARCH model

This paper proposes the hybrid model of autoregressive moving average (ARMA) and generalized autoregressive conditional heteroscedasticity (GARCH) to estimate and forecast the machine state based on vibration signal. The main idea in this study is to employ the linear ARMA model and the nonlinear GARCH model to explain the wear and fault condition of machine, respectively. The successful outcomes of the ARMA/GARCH prediction model can give obvious explanation for future states of machine, which enhance the worth of machine condition monitoring as well as condition-based maintenance in practical applications. The advance of the proposed model is verified in empirical results as applying for a real system of a methane compressor in a petrochemical plant.     

Development of an experimental technique to assess the permeability of metal coated polymer films

The experimental time required to measure water vapour permeability of barrier film using the cup method is extremely long. In this study, a new technique is proposed, based on light transmission. This fast and accurate method was first validated using model films constituted of aluminized PET (polyethylene terephthalate) with aluminium layers of different thicknesses (<100 nm). It was possible to show that the ‘illuminating’ method could advantageously be employed to control the film’s barrier properties during their fabrication. In a second step, the method was tentatively used to measure the changes in barrier properties over time, when the samples are submitted to severe hydrothermal ageing (70 °C, 90% relative humidity [RH]). It was concluded that the complex degradation mechanism prevents accurate measurement while ageing.     

BLOSSOMS: Building Lightweight Optimized Sensor Systems on a Massive Scale

As a joint effort between the Chinese Academy of Sciences and the Hong Kong University of Science and Technology, the BLOSSOMS sensor network project aims to identify research issues at all levels from practical applications down to the design of sensor nodes. In this project, a heterogeneous sensor array including different types of application-dependent sensors as well as monitoring sensors and intruding sensors are being developed. Application-dependent power-aware communication protocols are also being studied for communications among sensor nodes. An ontology-based middleware is built to relieve the burden of application developers from collecting, classifying and processing messy sensing contexts. This project is also developing a set of tools allowing researchers to model, simulate/emulate, analyze, and monitor various functions of sensor networks.     

Semantic Based Prefetching in News-on-Demand Video Servers

In video databases, a video document has two abstractions. The high level abstraction corresponds to the view in which the contents of that video document are seen by end users, and the low level abstraction corresponds to the physical organization of that video document. Due to the huge size of continuous data, reducing I/O has become a key issue. The latter has been mostly addressed by developing appropriate buffering techniques. In addition, prefetching techniques play a major role to meet the video data requirements. In this paper, we propose a novel prefetching strategy based not only on run-time information (objects access frequencies for example) but also on knowledge about clips structures. The proposed technique merges the two views of a video document to trigger prefetching at the video server level. Simulation experiments for a News-on-Demand application performed on different request scenarios show an improvement of about 18% in the buffer hit-rate with respect, first to the available buffer size and second to the request arrival rate.     

Efficient compilation of array iterators for Lustre

In this paper, we present a compilation scheme along with optimizations for array iterators in the synchronous data flow language Lustre. We present the iterators (inspired from functional languages mechanisms such as map and foldl…) and show how to compile them into efficient imperative code that manipulates arrays and loops instead of inefficient code were arrays are expanded into independent variables.     

Reconstruction and quantification of the carotid artery bifurcation from 3-D ultrasound images

Three-dimensional (3-D) ultrasound is a relatively new technique, which is well suited to imaging superficial blood vessels, and potentially provides a useful, noninvasive method for generating anatomically realistic 3-D models of the peripheral vasculature. Such models are essential for accurate simulation of blood flow using computational fluid dynamics (CFD), but may also be used to quantify atherosclerotic plaque more comprehensively than routine clinical methods. In this paper, we present a spline-based method for reconstructing the normal and diseased carotid artery bifurcation from images acquired using a freehand 3-D ultrasound system. The vessel wall (intima-media interface) and lumen surfaces are represented by a geometric model defined using smoothing splines. Using this coupled wall-lumen model, we demonstrate how plaque may be analyzed automatically to provide a comprehensive set of quantitative measures of size and shape, including established clinical measures, such as degree of (diameter) stenosis. The geometric accuracy of 3-D ultrasound reconstruction is assessed using pulsatile phantoms of the carotid bifurcation, and we conclude by demonstrating the in vivo application of the algorithms outlined to 3-D ultrasound scans from a series of patient carotid arteries.     

A two-front leach model for cement-stabilized heavy metal waste

Quantitative scanning electron microscope (SEM) studies of cement-stabilized waste specimens exposed to a leaching solution at constant pH in the range 4-7 have shown that the acid neutralization capacity (ANC) of the waste matrix is consumed at two consecutive leaching fronts. The first front is associated with the dissolution of portlandite (Ca(OH)2) and the partial reaction of calcium silicate hydrate (CSH) gel. The second front marks the dissolution of Ca-Al hydroxy sulfate minerals. The advancement of the first front is limited by the diffusion of OH- ions from the first front toward the leaching solution. The advancement of the second front, however, is controlled by the diffusion of H+ ions from the leaching solution toward the second front. Leaching of copper, zinc, and lead only occurs between the second front and the specimen surface. The leaching behavior of metals is modeled by considering that metals are leached from the waste matrix as a result of the advancement of the second front. The proposed model takes into account the leachable metal fraction in the waste matrix and the effect of metal remineralization on metal mobility.