The setting of Acoustic Emission detecting parameters in running of steel structured
Acoustic Emission technology is still at the starting stage of monitoring in domestic bridge. To resolve the problem that Acoustic Emission detection parameters in scene are determined. Based on lead-breaking tests confirm threshold and time parameter. Studying on the characteristic of signal propagated and the attenuation laws of velocity and amplitude, it gets references for Acoustic emission technique in detection of the bridge.
Continuous acoustic monitoring of grouted post-tensioned concrete bridges
The paper describes the first UK site installation of a monitoring system that detects the fracture of wires in post-tensioning tendons by listening with acoustic sensors attached to the surface of the concrete. Trials have shown the system to work reliably for grouted and ungrouted tendons. Acoustic events from other sources such as road traffic are discarded using software and hardware filters at the unattended site. Data from possible wire-fracture events are sent off site for final identification and positioning. The system is running continuously on site, on a viaduct, with close to 100% up-time. In open and blind trials on the viaduct, 41 out of 44 wire break or facsimile events were correctly located and identified and a further two were correctly located. The system can assist in the management of bridges where the post-tensioning system is at risk from corrosion.
Physical Ageing of the Research Reactor Core Structural Materials Due to Neutron Irradiation Exposure: a Review
A research reactor (RR) is a  nuclear reactor that has function to generate and utilize neutron flux and radiation ionization for  research purposes and industrial applications. More than 60% of current operating RRs have  been operated for 30 years or more. As the time passes, the functional capabilities of structures,  systems and components (SSCs) of those RRs deteriorate by physical ageing, which can be  caused by neutron irradiation exposure such as irradiation induced dislocation and  microstructural changes. To extend the lifetime and/or to avoid unplanned outages, ageing on  the safety related SSCs of RRs need to be properly managed. An ageing management is a  strategy to engineer, operate, maintenance, and control SSC degradation within acceptable limits. The purpose of this study is to review physical ageing of the core structural materials of  the RRs caused by neutron irradiation exposure. In order to achieve this objective, a wide range  of literatures are reviewed. Comprehensive discussions on irradiation behaviors are limited only  on reactor vessel and core support structure materials made from zirconium and beryllium as  well as their alloys, which are widely used in RRs. It is found that the stability of the mechanical  properties of zirconium and beryllium as well as their alloys was mostly affected by the neutron  fluences and temperatures.