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Abstract Structural health monitoring (SHM) is the automation of the condition assessment process of an engineered system. When applied to geometrically large components or structures, such as those found in civil and aerospace infrastructure and systems, a critical challenge is in designing the sensing solution that could yield actionable information. This is a difficult task to conduct cost-effectively, because of the large surfaces under consideration and the localized nature of typical defects and damages. There have been significant research efforts in empowering conventional measurement technologies for applications to SHM in order to improve performance of the condition assessment process. Yet, the field implementation of these SHM solutions is still in its infancy, attributable to various economic and technical challenges. The objective of this Roadmap publication is to discuss modern measurement technologies that were developed for SHM purposes, along with their associated challenges and opportunities, and to provide a path to research and development efforts that could yield impactful field applications. The Roadmap is organized into four sections: distributed embedded sensing systems, distributed surface sensing systems, multifunctional materials, and remote sensing. Recognizing that many measurement technologies may overlap between sections, we define distributed sensing solutions as those that involve or imply the utilization of numbers of sensors geometrically organized within (embedded) or over (surface) the monitored component or system. Multi-functional materials are sensing solutions that combine multiple capabilities, for example those also serving structural functions. Remote sensing are solutions that are contactless, for example cell phones, drones, and satellites. It also includes the notion of remotely controlled robots.

Abstract Portability, ease of use, robustness, and system cost are important parameters in designing flexible measurement systems. To this end, we introduce a cost-efficient and open-source measurement system based on consumer hardware for measuring air properties such as temperature, humidity, particle concentration in order to determine indoor air quality, thermal comfort, or air pollution. Cost and energy efficient sensor modules are integrated into an USB-based measurement interface that supports a wide range of communication protocols including Serial Peripheral Interface, Inter Integrated Circuit, Recommended Standard 232 and Recommended Standard 485. Moreover, the system provides a web interface and an application programming-interface that enables real time access to sensor data. In this paper we present the design of the hardware set-up, an overview of the sensors supported so far, and the software architecture as well as application examples.

Abstract This manuscript presents a minimum settings calibration method for low-cost tri-axial inertial measurement units (IMUs) and magnetometers. At first, we analyze the major defect of the traditional calibration methods for tri-axial accelerometers and magnetometers. To fix that problem, we utilize the ellipsoid model to calibrate the tri-axial accelerometer and magnetometer preliminarily, then complete the calibration work with at least two reference angular positions, and prove that two reference angular positions are minimum requirements in the calibration progress. Next, the tri-axial gyroscope is calibrated based on the nonlinear cost function with the aid of the pre-calibrated accelerometer. The simulation and real-world experiment results show that the proposed method is practical and effective, suggesting that this technique is a viable candidate for the applications that require IMUs and magnetometers.

Aiming at the calibration of in-service strain sensing systems for structural health monitoring (SHM), a calibration method adapting to complex in-situ conditions is proposed. A calibration framework composed of measured variable, excitation source, reference system and sensing system is defined. By analysing the mechanism of in-situ calibration, two measurement models are deduced for instantaneous and intermediate errors of the sensing system respectively. To discover the effects of the ambient temperature on the calibration process, the experiments are conducted using a temperature test chamber, and then the qualitative analysis and quantitative estimation are performed. The results show that: (1) With the variation of temperature, the responses of both resistance strain gauges (RSS) and fiber optic strain sensors (FOS) change visibly; (2) The relative strain deviations between the sensing system (SS) and the reference sensing system (RS) within -10℃~50℃ fluctuate in a narrow range, for example 0.015~0.023 for RSS and 0.382~0.404 for FOS in this study; (3) The range of the deviations between SS and RS that is affected by temperature can be estimated with the proposed method, for example, 4.6μe for RSS and 18.1μe for FOS, respectively, with a confidence level of 95%.

Radon gas is the largest source of public exposure to naturally occurring radioactivity. However, radon is also a useful tracer for understanding atmospheric processes, assessing the accuracy of chemical transport models, and enabling integrated emissions estimates of greenhouse gases. A sound metrological system for low level atmospheric radon observations is therefore needed for the benefit of the atmospheric, climate and radiation protection research communities. To this end, here we present a new calibration method for activity concentrations below 20 Bq m−3 and a prototype of the first portable radon monitor capable of achieving uncertainties of 5% (at k = 2) at these concentrations. Compliance checking of policy-driven regulations regarding greenhouse gas (GHG) emissions is an essential component of climate change mitigation efforts. Independent, reliable 'top down' methods that can be applied consistently for estimating local- to regional-scale GHG emissions (such as the radon tracer method (RTM)) are an essential part of this process. The RTM relies upon observed radon and GHG concentrations and measured or modeled radon fluxes. Reliable radon flux maps could also significantly aid EU member states comply with European COUNCIL DIRECTIVE 2013/59/EURATOM. This article also introduces the traceRadon project, key aims of which include outlining a standardized approach for application of the RTM, creating infrastructure with a traceability chain for radon concentration and radon flux measurements, and developing tools for the validation of radon flux models. Since radon progeny dominate the terrestrial gamma dose rate, the planned traceRadon activities are also expected to improve the sensitivity of radiation protection early warning networks because of the correlation known to exist between radon flux and ambient equivalent dose rates. International audience