3D measures exploitation for a monocular semi-supervised fall detection system

Falls have been reported as the leading cause of injury-related visits to emergency departments and the primary etiology of accidental deaths in elderly. Thus, the development of robust home surveillance systems is of great importance. In this article, such a system is presented, which tries to address the fall detection problem through visual cues. The proposed methodology utilizes a fast, real-time background subtraction algorithm, based on motion information in the scene and pixels intensity, capable to operate properly in dynamically changing visual conditions, in order to detect the foreground object. At the same time, it exploits 3D space’s measures, through automatic camera calibration, to increase the robustness of fall detection algorithm which is based on semi-supervised learning approach. The above system uses a single monocular camera and is characterized by minimal computational cost and memory requirements that make it suitable for real-time large scale implementations.     

Design and Testing of a Robotic System for mr Image-guided Interventions

The effective integration of robotics together with magnetic resonance (mr) technology is expected to facilitate the real-time guidance of various diagnostic and therapeutic interventions. Specially designed robotic manipulators are required for this purpose, the development of which is a challenging task given the strong magnetic fields and the space limitations that characterize the mr scanning environment. A prototype mr-compatible manipulator is presented, designed to operate inside cylindrical mr scanners. It was developed for the study of minimally invasive diagnostic and therapeutic interventions in the abdominal and thoracic area with real-time mr image guidance. Initial tests were performed inside a high-field clinical mr scanner and included mr-compatibility tests and phantom studies on image-guided targeting.     

Concentration and temperature dependence of diffusional deborah number during dodecane transport in crosslinked polystyrene

The diffusional Deborah number, De, defined as the ratio of characteristic relaxation time to characteristic diffusion time was determined as a function of concentration and temperature in the dodecane transport process in polystyrene. The characteristic relaxation time was obtained from the viscoelastic properties of dodecane/polystyrene systems measured by a dynamic mechanical analyzer. The characteristic diffusion time was obtained from the concentration and temperature dependence of the diffusion coefficient measured by NMR PGSE method. Above the room temperature the Deborah number changed significantly during isothermal transport process; however, the transport mechanism did not deviate from the Fickian transport as the order of De was still greater than 1. Around the room temperature the transport mechanisms represented by the resulting diffusional Deborah number changed significantly as the order of magnitude approached 1 with the temperature decreasing from 50°C to the room temperature. The transport mechanism predicted from the diffusional Deborah number was verified by the diffusional exponent, n, of an exponential time-dependence of the penetrant uptake.     

Combining self-organizing neural nets with multivariate statistics for efficient color image retrieval

An efficient novel strategy for color-based image retrieval is introduced. It is a hybrid approach combining a data compression scheme based on self-organizing neural networks with a nonparametric statistical test for comparing vectorial distributions. First, the color content in each image is summarized by representative RGB-vectors extracted using the Neural-Gas network. The similarity between two images is then assessed as commonality between the corresponding representative color distributions and quantified using the multivariate Wald–Wolfowitz test. Experimental results drawn from the application to a diverse collection of color images show a significantly improved performance (approximately 10–15% higher) relative to both the popular, simplistic approach of color histogram and the sophisticated, computationally demanding technique of Earth Mover’s Distance.     

A Model Based on the Assessment of Intrinsic Creep Resistance Concept

In the present study a simple model is proposed to assess creep behavior. The model is applied to experimental results performed on austenitic steel X8 CrNiMoNb 16 16. The model is based on a modification of the Levy‐Mises equation for plasticity to consider creep time effects, introducing as a parameter the intrinsic creep resistance. The assessment of creep behavior applied for monotonic and two stages loading data is good. The model could assess negative creep strain rates as well as damage accumulation observed as an increase of the minimum creep rate after each reloading at the same stress level in two stages tests.     

Wideband numerical modelling and performance optimisation of arbitrarily-shaped anechoic chambers via an unconditionally stable time-domain technique

A 3-D curvilinear alternating-direction implicit finite-difference time-domain (ADI-FDTD) algorithm for the broadband analysis and optimised design of anechoic and semi-anechoic chambers with arbitrary shape is presented in this paper. The unconditionally stable and frequency-dependent method develops a new family of spatial/temporal forms which reduce the critical dispersion errors of existing approaches and allow the precise performance evaluation of essential components or dissimilar lossy absorbers before their actual construction. Hence, the proposed technique circumvents prolonged simulations via temporal increments significantly beyond the Courant limit and achieves substantial accuracy even for highly curved details. Numerical results, concerning several realistic structures as well as comparisons with measured data obtained according to specific international EMC standards, demonstrate the preceding advantages and lead to optimal chamber configurations.This work has been supported by the State Scholarships Foundation of Greece (I.K.Y. – Athens, Greece) under Postdoctoral Research Scholarship No. 475/2003–2004.     

Audio source separation: solutions and problems

The problem of separating out a number of audio sources observed from an array of microphones in a real room environment has received a great deal of attention in the past decade. While there are now a number of workable methods that can even deal with relatively high reverberation (IEEE Trans Audio Speech Process, 2003; 11 :489–497), a number of interesting problems still remain. In this paper, the authors review the methods based around independent component analysis, discussing the various choices available in algorithm design. We then explore the issue of sensitivity to speaker movement which appears to impose fundamental limitations on BSS performance. Copyright © 2004 John Wiley & Sons, Ltd.     

Air Quality Management Using a Multi-Agent System

Management of urban atmospheric pollution necessitates advanced modeling and information processing techniques. The design of the prototype system DNEMO, which is based on a distributed adaptive problem-solving approach is the focus of the research reported in this paper. Issues covered in the paper relate to the distributed nature of this environmental problem, handling noise and uncertainty in monitoring data, achieving graceful degradation of performance and system robustness, and adaptation of system performance to long-term evolution of the monitored phenomena. The research reported can be applicable to a broad class of environmental monitoring applications, since the problems addressed are common to many environmental problems.     

Structural analysis of charged polymeric networks

Summary A new model was developed to accurately describe the swelling behavior of charged polymeric networks. The model incorporates elastic, mixing and ionic contributions to the chemical potential. Changes in the equilibrium degree of swelling as a function of pH can be predicted.