Rigorous analysis of internal resonances in 3-D hybrid FE-BIE formulations by means of the Poincaré-Steklov operator

3-D hybrid finite-element (FE) boundary integral equation (BIE) formulations are widely used because of their ability to simulate large inhomogeneous structures in both open and bounded simulation domains by applying each method where it is the most efficient. However, some formulations suffer from breakdown frequencies at which the solution is not uniquely defined and errors are introduced due to internal resonances. In this paper, we investigate the occurrence of spurious solutions resulting from these resonances by using the concept of the Poincare-Steklov or Dirichlet-to-Neumann operator, which provides a relation between the tangential electric field and the electric current on the boundary of a domain. By identifying this operator in both the FE and BIE method, several new properties of internal resonances in 3-D hybrid FE-BIE formulations are easily derived. Several conformal and nonconformal formulations are studied and the theory is then applied to a scattering problem

Efficient calculation of coupling matrices for a decoupled FE/BIE formulation

This paper presents an efficient method for calculating coupling matrices that occur in a decoupled hybrid finite element / boundary integral equation (FE/BIE) system. These coupling matrices represent projections from basis functions of one domain to basis functions of an other domain. Based on a technique for evaluating singular integrals over polyhedral domains, it becomes possible to calculate the projection integrals analytically, instead of relying on quadrature integration rules. It is shown that this reduces the CPU-time, whereas the accuracy remains correct up to machine precision

A single-chip CMOS pulse oximeter with on-chip lock-in detection

Pulse oximetry is a noninvasive and continuous method for monitoring the blood oxygen saturation level. This paper presents the design and testing of a single-chip pulse oximeter fabricated in a 0.35 µm CMOS process. The chip includes photodiode, transimpedance amplifier, analogue band-pass filters, analogue-to-digital converters, digital signal processor and LED timing control. The experimentally measured AC and DC characteristics of individual circuits including the DC output voltage of the transimpedance amplifier, transimpedance gain of the transimpedance amplifier, and the central frequency and bandwidth of the analogue band-pass filters, show a good match (within 1%) with the circuit simulations. With modulated light source and integrated lock-in detection the sensor effectively suppresses the interference from ambient light and 1/f noise. In a breath hold and release experiment the single chip sensor demonstrates consistent and comparable performance to commercial pulse oximetry devices with a mean of 1.2% difference. The single-chip sensor enables a compact and robust design solution that offers a route towards wearable devices for health monitorin

Homogeneous Simulation: the Effective Integration Solution for Smart Systems

This work provides a taxonomy of abstraction levels and design domains of a smart system, for analyzing the support of simulation/co-simulation and the effect of homogeneity/heterogeneity on simulation. The paper presents also flows and tools that can be exploited to gain homogeneous simulation. The overall approach is applied to a complex industrial case study

Homogeneous Simulation: the Effective Integration Solution for Smart Systems

This work provides a taxonomy of abstraction levels and design domains of a smart system, for analyzing the support of simulation/co-simulation and the effect of homogeneity/heterogeneity on simulation. The paper presents also flows and tools that can be exploited to gain homogeneous simulation. The overall approach is applied to a complex industrial case study