Level‐Sets fields,placement and velocity based formulations of contact‐impact problems

By introducing unknown Sign‐like fields of Level‐Sets type, the Signorini‐Moreau dynamic contact conditions are set merely as boundary equations. From this setting, a continuous hybrid weak–strong formulation for dynamic contact between deformable solids is derived and a new Lagrangian formulation (we call stabilized) generalizing both the classical and augmented ones is obtained. Friction phenomena are treated similarly. In the global problem, the irregular Sign‐like fields stand for the intrinsic contact unknown ones. This problem is discretized by means of time, space and collocation schemes. Some numerical experimentations are carried out, showing the potential of our developments. Copyright © 2006 John Wiley & Sons, Ltd.     

Production Principles and Technological Development of Novel Woven Spacer Preforms and Integrated Stiffener Structures

3D textile preforms offer a high potential to increase mechanical properties of composites and/or decrease manufacturing costs. Within the scope of this study, production principles were developed for complex spacer preforms and integrated stiffeners. These principles were applied through technological further development of the well-known face-to-face and terry weaving techniques. Various woven preforms were produced with Glass fibre/Polypropylene (GF/PP) Commingled yarns, however, the technology is suitable for any type of reinforcement yarns. U-shaped woven spacer preform was consolidated into a sandwich composite component for lightweight applications.     

Neural solutions to interact with computers by hand gesture recognition

This paper attempts to present a vision-based interface which interacts with computers by hand gesture recognition. This work aims at creating a natural and intuitive application employing both static and dynamic hand gestures. The proposed application can be summarized in three main steps: hands detection in a video, hands tracking and converting hand shapes or trajectories into computer commands. To accomplish this application, a classification phase is paramount whether at the part of hand detection, or at the phase of “commanding computers”. For this reason, we have proposed to use a wavelet network classifier (WNC) learnt by fast wavelet transform (FWT). To emphasize the robustness of this classifier, we have used a neural network classifier (NNC) version in order to compare the two classifiers’ performances aiming at proving the strength of our proposed one. Global rates given by experimental results show the effectiveness of our proposed approaches of hand detection, hand tracking and hand gesture recognition. The comparison of the two classifier’s result helps to choose the best classifier, which can improve the performances of our application.     

A Fast and Reliable Process to Fabricate Regenerated Silk Fibroin Solution from Degummed Silk in 4 Hours

Silk fibroin has a high potential for use in several approaches for technological and biomedical applications. However, industrial production has been difficult to date due to the lengthy manufacturing process. Thus, this work investigates a novel procedure for the isolation of non-degraded regenerated silk fibroin that significantly reduces the processing time from 52 h for the standard methods to only 4 h. The replacement of the standard degumming protocol by repeated short-term microwave treatments enabled the generation of non-degraded degummed silk fibroin. Subsequently, a ZnCl₂ solution was used to completely solubilize the degummed fibroin at only 45 °C with an incubation time of only 1 h. Desalting was performed by gel filtration. Based on these modifications, it was possible to generate a cytocompatible aqueous silk fibroin solution from degummed silk within only 4 h, thus shortening the total process time by 48 h without degrading the quality of the isolated silk fibroin solution.     

Analytic Beta-Wavelet Transform-Based Digital Image Watermarking for Secure Transmission

The rapid development in the information technology field has introduced digital watermark technologies as a solution to prevent unauthorized copying and redistribution of data. This article introduces a self-embedded image verification and integrity scheme. The images are firstly split into dedicated segments of the same block sizes. Then, different Analytic Beta-Wavelet (ABW) orthogonal filters are utilized for embedding a self-segment watermark for image segment using a predefined method. ABW orthogonal filter coefficients are estimated to improve image reconstruction under different block sizes. We conduct a comparative study comparing the watermarked images using three kinds of ABW filters for block sizes 64 × 64, 128 × 128, and 256 × 256. We embed the watermark using the ABW-based image watermarking method in the 2-level middle frequency sub-bands of the ABW digital image coefficients. The imperceptibility and robustness of the ABW-based image watermarking method image is evaluated based on the Peak Signal to Noise Ratio (PSNR) and Correlation coefficient values. From the implementation results, we came to know that this ABW-based image watermarking method can withstand many image manipulations compared to other existing methods.     

Efficient algorithm for automatic road sign recognition and its hardware implementation

The automatic detection of road signs is an application that alerts the vehicle’s driver of the presence of signals and invites him to react on time in the aim to avoid potential traffic accidents. This application can thus improve the road safety of persons and vehicles traveling in the road. Several techniques and algorithms allowing automatic detection of road signs are developed and implemented in software and do not allow embedded application. We propose in this work an efficient algorithm and its hardware implementation in an embedded system running in real time. In this paper we propose to implement the application of automatic recognition of road signs in real time by optimizing the techniques used in different phases of the recognition process. The system is implemented in a Virtex4 FPGA family which is connected to a camera mounted in the moving vehicle. The system can be integrated into the dashboard of the vehicle. The performance of the system shows a good compromise between speed and efficiency.     

Sectors associations and similarities in input-output systems: An application of dual scaling and fuzzy logic to Canada and the United States

Various authors addressed interindustry linkages in the context of input-output systems, however many focused on the identification of key sectors in the economy. Sonis et al. (1996) offered as a field of influence theory an alternative approach focusing on the analytical importance of elements and combinations of elements. In an attempt to further the understanding of the linkages in an input-output system, the objective of this paper is to examine the cluster structure of sales and purchases profiles when the principle of excluded middle is violated by the use of fuzzy sets. The identification of fuzzy clusters is based on an analysis to derive an alternative decomposition ofinterindustry flows (Dridi and Hewings 2002), it is a complementary approach to the so-called Matrioshka principal (Sonis and Hewings 1990) and will be presented first; the approach looks into the hierarchy of the statistical dependence between supply and demand in input-output systems. The analysis on the cluster structure and the interindustry flows is conducted using the data analysis technique known as dual scaling (Nishisato 1980, 1994). Results of the analysis will be illustrated using input-output tables of the US and Canada. An earlier draft of this paper was presented at the 41st Annual Meeting of the Western Regional Science Association-Monterey, California (February 17–20, 2002), comments from conference participants, J. Le Gallo, and two anonymous referees are acknowledged. The usual disclaimer applies.     

Electrical modeling of packaging discontinuities: A general methodology based on the three-dimensional TLM concept

A general methodology for modeling packages using the three-dimensional (3D) TLM method is presented. S parameters are calculated from reflected and transmitted signals, and electrical parameters of equivalent networks are extracted. Frequency domain results (up to 30 GHz) are presented for a microstrip right-angle bend, a cross junction, and vias. The purpose of this article is to demonstrate the possibilities of using the 3D TLM method for electrical modeling in packaging applications.