Comparison of numerical models for Acoustic Emission propagation

Abstract Acoustic Emissions (AE) are at the basis of extremely accurate and reliable monitoring systems. Within the SmartBench project, data regarding structural health of components are gathered in a database in order to make safety integrated, operative and smart. An accurate modelling of wave propagation is a necessary requirement for a proper design of sensor networks as well as for data interpretation. Numerical simulations of the transient behavior of structural systems are well-established in this field but, on the minus side, they are very expensive in terms of computational time and resources. This paper reports different instances of AE propagation through metallic media. Bulk waves and guided waves are both investigated by means of 2D and 3D models and resorting to different software. Obtained results are cross-checked and computational times are compared as well. As a last point, High Performance Computing is applied to the case of waves simulation in order to get a significant reduction of the required computational time

AUTONOMOUS SYSTEMS & SAFETY ISSUES: THE ROADMAP TO ENABLE NEW ADVANCES IN INDUSTRIAL APPLICATIONS

The paper addresses the safety issues related to the development of new solutions based on autonomous systems for industrial applications and the necessity to develop experimental environments for investigating these cases; a set of examples is proposed in order to provide cases and challenges as well as to suggest approaches to address these problems

Adaptive rate admission control for DS-CDMA cellular systems

The paper proposes an adaptive admission control (AC) policy, that reduces call dropping probability, resorting to rate adaptation in accordance with the instantaneous connection configurations. We describe the philosophy of the proposed adaptive scheme and analyze the effective call dropping probability when considering a single cell UMTS scenario with an additive white Gaussian noise (AWGN) channel. Our simulations demonstrate that, by employing the proposed scheme, the network performance can be extremely increased while the quality of service (QoS) requested is respected

A priority based admission control strategy for WCDMA systems

Future wireless systems need higher support in terms of QoS support. In particular, when several connections with different QoS attributes are allowed, a prioritization system has to be foreseen. In UMTS and other systems that exploit the WCDMA approach, the problem of mitigating multiple access interference arises, too. Admission control algorithms have been introduced in the literature in order to prevent any congestion status in the network. An admission control algorithm that works by exploiting the current interference level is presented; moreover, each type of traffic is managed in order to respect its QoS in terms of priority

An efficient soft admission control technique for wireless communications

In this paper, an innovative Admission Control (AC) policy for CDMA wireless networks, based on minimizing the Multiple-Access-Interference (MAI), is introduced. According to our proposal, an incoming connection is accepted whenever the QoS constraints, for all communications, are respected, that is, the Signal-to-Interference-plus-Noise-Ratio (SINR) is kept under control. This parameter mainly depends on traffic load variations. Thus, the MAI arising from a new connection must be considered. This problem can be proactively faced by characterizing MAI and correctly estimating its value. Furthermore, two approaches are presented, named, respectively, Static Soft AC and Dynamic Soft AC; the latter involving a dynamic power management. Analytical models describing the first approach are investigated and validated by means of simulations performed on a typical uplink UMTS environment. Moreover, a remarkable gain of the second approach, in terms of dropping probability, is highlighted without, thus rendering our approach a proper candidate for variable network traffic management

An advanced admission control algorithm based on SIR estimation for CDMA wireless systems

This paper deals with an advanced admission control (AC) scheme that estimates the requesting connections signal-to-noise plus interference ratio (SINR) by means of accurate multiple access interference (MAI) analysis results. This algorithm verifies the possibility of a new call admission by valuating if a power configuration exists, whose predicted SINR values satisfy each QoS constraints. Numerical simulations, closely related to the UMTS system, underline a remarkable number of active users increase up to four times traditional AC policies, together with the maximisation of QoS requirements

A wireless sensor node for acoustic emission non-destructive testing

In this paper a wireless sensor node for Acoustic Emission (AE) analysis has been proposed. This node can be used to simplify the in-force procedures for the structural integrity verification of pressure tanks. This procedure is currently based on periodic checks and consequently does not allow a real-time monitoring. The proposed wireless sensor node is compatible with commonly used AE sensors available on market and can be integrated in a wireless sensor network for real time monitoring increasing the security of the plant