Instantaneous vehicle fuel consumption estimation using smartphones and Recurrent Neural Networks

The high level of air pollution in urban areas, caused in no small extent by road transport, requires the implementation of continuous and accurate monitoring techniques if emissions are to be minimized. The primary motivation for this paper is to enable fine spatiotemporal monitoring based on crowd sensing, whereby the instantaneous fuel consumption of a vehicle is estimated using smartphone measurements. To this end, a surrogate method based on indirect monitoring using Recurrent Neural Networks (RNNs) that process a smartphone's GPS position, speed, altitude, acceleration and number of visible satellites is proposed. Extensive field trials were conducted to gather smartphone and fuel consumption data at a wide range of driving conditions. Two different RNN types were explored, and a parametric analysis was performed to define a suitable architecture. Various training methods for tuning the RNN were evaluated based on performance and computational burden. The resulting estimator was compared with others found in the literature, and the results confirm its superior performance. The potential impact of the proposed method is noteworthy as it can facilitate accurate monitoring of in-use vehicle fuel consumption and emissions at large scales by exploiting available smartphone measurements.</p

Determination of plasticity following deformation and welding of austenitic stainless steel

Intergranular strain has been associated with high-temperature cracking of welded pipework in 316H austenitic stainless steel material used in nuclear power plant heat exchangers. In this study, neutron diffraction has been used to study the development of intergranular strains in plastically-deformed and welded 316H stainless steel. Measurements have been made of the intergranular strain evolution with increasing plastic strain in base material, and correlated with further measurements made in samples extracted from welded pipes, where the pipes were welded following plastic deformation to different levels of plastic strain. Strong tensile strain evolution was seen on the compliant 200 grain family. The results were correlated with various proxy measures of plastic strain, including hardness and diffraction peak width, and excellent agreement was obtained

Finite Element Analysis of Laser Peening of Thin Aluminum Structures

Laser shock peening has become a commonly applied industrial surface treatment, particularly for high-strength steel and titanium components. Effective application to aluminum alloys, especially in the thin sections common in aerospace structures, has proved more challenging. Previous work has shown that some peening conditions can introduce at-surface tensile residual stress in thin Al sections. In this study, we employ finite element modeling to identify the conditions that cause this to occur, and show how these adverse effects can be mitigated through selection of peen parameters and patterning

Background estimation in a wide-field background-limited instrument such as Fermi GBM

The supporting instrument on board the Fermi Gamma-ray Space Telescope, the Gamma-ray Burst Monitor (GBM) is a wide-field gamma-ray monitor composed of 14 individual scintillation detectors, with a field of view which encompasses the entire unocculted sky. Primarily designed as transient monitors, the conventional method for background determination with GBM-like instruments is to time interpolate intervals before and after the source as a polynomial. This is generally sufficient for sharp impulsive phenomena such as Gamma-Ray Bursts (GRBs) which are characterised by impulsive peaks with sharp rises, often highly structured, and easily distinguishable against instrumental backgrounds. However, smoother long lived emission, such as observed in solar flares and some GRBs, would be difficult to detect in a background-limited instrument using this method. We present here a description of a technique which uses the rates from adjacent days when the satellite has approximately the same geographical footprint to distinguish low-level emission from the instrumental background. We present results from the application of this technique to GBM data and discuss the implementation of it in a generalised background limited detector in a non-equatorial orbit.Comment: Proceedings of SPIE, Vo. 8443, Paper No. 8443-3

Development and application of the contour method to determine the residual stresses in thin laser-peened aluminium alloy plates

The contour method was applied to obtain residual stress fields in a laser-peened 2.0-mm-thick Al2024-T351 sample. In order to remove the effects of near-surface wire electro-discharge machining (EDM) cutting artefacts on the measured residual stresses, sacrificial blocks were attached to both surfaces of the thin sample with a polymer-based glue doped with silver particles. A data analysis routine based on bivariate spline smoothing was conducted to obtain a 2D residual stress map. The results were compared with incremental hole drilling, and X-ray diffraction and layer removal techniques. The results are in good agreement in terms of the magnitudes and the location of the peak stresses, with the exception of the contour method results. Owing to the low thickness of the samples, the data analysis is very sensitive to the parameters used in the spline fitting, leading to fluctuation in the results. It is concluded that the contour method can be applied to thin samples, however, extra attention is required. Since the uncertainty is higher compared to the conventional contour method results, it is good practice to compare the results with at least one other experimental method