Christos Biniaris

A dual-band inverted-F antenna printed on a PC card for the ISM and UNNI bands

This paper describes a novel single feed dual-band inverted-F antenna (IFA) operating in the ISM and UNNI bands. The antenna is printed on a PC card and is suitable for Bluetooth and wireless LAN 802.11a applications. The three-dimensional finite element method (FEM) electromagnetic simulator, HFSS, is used in the design simulation of the IFA/PC card system. The results exhibit a proper operation of the antenna in terms of return loss, bandwidth and efficiency at both bands.

Implementing distributed FDTD codes with Java mobile agents

The main objective of this work is to highlight the advantages of coupling Java FDTD implementation with the mobile-agent computing paradigm, and to promote this approach as a flexible and valuable tool for the distributed solution of complex and large-scale problems. Therefore, we present key issues related to the distributed implementation of a finite-difference time-domain (FDTD) code using Java mobile agents. The Java object-oriented FDTD code is described, and special agent communication and synchronization aspects related to FDTD are presented in detail.

Measurement of heart rate and respiratory rate using a textile-based wearable device in heart failure patients

Changes in heart rate (HR) and respiratory rate (RespR) may be used as markers of early decompensation in chronic heart failure (CHF) patients monitored at home. Aiming at improving quality of care and at reducing hospitalization rate and health care costs in CHF, progress in technology has led to the development of small portable and even wearable devices for the acquisition and transmission of relevant vital signs to a remote monitoring centre. This paper describes a signal acquisition and processing system, based on a wearable textile-based device with sensors for the measurement of one-lead ECG and chest movement, and focuses on the algorithms for HR and RespR evaluation. An electronic board collects and transmits these signals to a PDA, which sends them via Wi-Fi to a home gateway where the HR and the RespR time series are produced. The home gateway packs the data with other vital signs collected by using different devices and sends them in XML format to a central repository where a clinical decision support system can use them for the detection of early decompensation episodes. The system has successfully overcome a preliminary test phase and is ready for more extensive tests in a real clinical environment.

Webmages: An agent platform based on web services

WebMages (Web-based Mobile AGEnt System) is a mobile agent platform based on the integration of the mobile agent computing paradigm with Web Services. The resulting platform provides a lightweight agent run-time environment inside a web container, thus adding agent functionality to existing web servers. The platforms components are deployed as Web Services, with SOAP (Simple Object Access Protocol) over HTTP acting as the necessary communication channel. Potential performance enhancements related to the XML parsing of the transferred data and to the difference in performance between the Apache SOAP library and the Apache AXIS engine are also presented and discussed.

Implementation of a mobile agent platform based on Web services

This paper proposes a framework that allows a convenient and flexible implementation of a mobile agent platform. We present an architecture that integrates the mobile agent computing paradigm with Web services to achieve the development of a web-integrated mobile agent platform. The platform components are deployed on Apache Tomcat web servers and the implementation is based on the Apache Java SOAP library. As it will be demonstrated, the Web services model perfectly matches the demands of the architecture of a mobile agent platform providing a straightforward design and implementation of a platform agnostic Web-based mobile agent tool.

Reduced complexity analysis of microstrip patch arrays, conformally mounted to a cylindrical conducting surface

Standard integral equation techniques, such as the moment method (MoM) face difficulties for very large antenna sizes, since the memory and CPU time they require may increase beyond computational limits. The method of auxiliary sources (MAS) demands substantially lower CPU time than MoM, retaining, nevertheless, the MoM accuracy. Unfortunately, its capabilities are depleted when applied to thin or open structures, due to the mandatory proximity of source and collocation points occurring in such geometries. The modified method of auxiliary sources (MMAS) has been developed to circumvent this difficulty, and has been successfully applied to the analysis of microstrip patch antennas, even when the dielectric substrate is thin enough to render conventional MAS inapplicable. In this paper, the MMAS is applied to the analysis of microstrip patch arrays, conformal to cylindrical surfaces, a model that simulates a communication antenna mounted to an aircraft fuselage. Several unpublished features of MMAS are discussed, whereas extensive, recently produced numerical results are presented and compared to reference solutions, validating the reliability and versatility of the method.

Biomedical data acquisition and transmission infrastructure in the HEARTFAID platform

Chronic heart failure (CHF) is a complex cardiovascular syndrome whose management requires a complex clinical program involving the acquisition, integration and interpretation of heterogeneous biomedical data and information. Within the EU FP6 project HEARTFAID, an integrated platform of services has been developed to assist CHF stakeholders in their routine workflow and to provide an optimal management of CHF patients, by exploiting the most advanced technologies and instruments for diagnostic data processing. In this paper, we describe the platform component responsible for the acquisition and transmission of biomedical data from several medical devices and sensors.

A Web-based distributed computing framework for antenna array modeling

The purpose of this article is to present a distributed computing framework that is used as a purely Web-based simulation environment for antenna array modeling. The framework adopts a three-tier architecture. The front-end part is mainly based on dynamic Web pages for the selection of antenna parameters, enhanced by the VRML standard for visualization of the geometry and results. The middle part of the architecture is based on Java servlets, which are responsible for handling the front-end communication with the remote user and setting up the simulation. Finally, the back end of the architecture is responsible to distribute the computations to a set of computing nodes. This part employs a purely Web-based mobile agent platform, responsible for the execution of partial simulation code to remote hosts. In the context of the article we demonstrate the applicability of the framework in antenna array modeling by presenting a specific parametric simulation of conformal antenna arrays.

A Three-Dimensional Object-Oriented Distributed Finite Element Solver Based on Mobile Agent Technology

We present an object-oriented distributed finite element method (FEM) solver for three-dimensional scattering problems, implemented on a network of workstations. The solution of the resulting sparse linear system is performed using the conjugate orthogonal conjugate gradient method. The entire implementation is based on the Java programming language, and the distributed solution is achieved via the use of mobile agent technology. Since the paper aims mainly to demonstrate the benefits of using Java and mobile agents as the technologies to develop complex FEM applications and implement them in a distributed environment, its main core is devoted to a thorough description of the distributed-object-oriented implementation, focusing on inter-agent communication and synchronization aspects. Numerical results are presented, which prove that our approach is a promising technique for the efficient solution of complex FEM modeling problems.

Mobile agent based distributed computations of numerical modeling problems in EMC applications

We present a generic mobile agent based framework for efficient distributed parametric simulations of computationally costly EMC modeling problems, on a network of workstations. The mobile agents gather information concerning the hosts of the network. transfer the native code there. handle its execution according to a scheduling policy and collect the results. Such a framework enables scientists and engineers to improve and shorten design processes. As a case study. we present an EMC problem related to the coupling of electromagnetic waves with non-visible obstacles.