Firefighting protective clothing is an essential equipment that can protect firefighters from burn injuries during the firefighting process. However, it is still a challenge to detect the damage of firefighting protective clothing at an early stage when firefighters are exposed to excessively high temperature in fire cases. Herein, an ultralight self-powered fire alarm electronic textile (SFA e-textile) based on conductive aerogel fiber that comprises calcium alginate (CA), Fe3O4 nanoparticles (Fe3O4 NPs), and silver nanowires (Ag NWs) was developed, which achieved ultrasensitive temperature monitoring and energy harvesting in firefighting clothing. The resulting SFA e-textile was integrated into firefighting protective clothing to realize wide-range temperature sensing at 100–400 °C and repeatable fire warning capability, which could timely transmit an alarm signal to the wearer before the firefighting protective clothing malfunctioned in extreme fire environments. In addition, a self-powered fire self-rescue location system was further established based on the SFA e-textile that can help rescuers search and rescue trapped firefighters in fire cases. The power in the self-powered fire location system was offered by an SFA e-textile-based triboelectric nanogenerator (TENG). This work provided a useful design strategy for the preparation of ultralight wearable temperature-monitoring SFA e-textile used in firefighting protective clothing.

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This paper aims to investigate the relationship between torque and muscle morphological change, which is derived from ultrasound image sequence and termed as sonomyography (SMG), during isometric ramp contraction of the rectus femoris (RF) muscle, and to further compare SMG with the electromyography (EMG) and mechanomyography (MMG), which represent the electrical and mechanical activities of the muscle. Nine subjects performed isometric ramp contraction of knee up to 90% of the maximal voluntary contraction (MVC) at speeds of 45, 22.5 and 15% MVC/s, and EMG, MMG and ultrasonography were simultaneously recorded from the RF muscle. Cross-sectional area, which was referred to as SMG, was automatically extracted from continuously captured ultrasound images using a newly developed image tracking algorithm. Polynomial regression analyses were applied to fit the EMG/MMG/SMG-to-torque relationships, and the regression coefficients of EMG, MMG, and SMG were compared. Moreover, the effect of contraction speed on SMG/EMG/MMG-to-torque relationships was tested by pair-wise comparisons of the mean relationship curves at different speeds for EMG, MMG and SMG. The results show that continuous SMG could provide important morphological parameters of continuous muscle contraction. Compared with EMG and MMG, SMG exhibits different changing patterns with the increase of torque during voluntary isometric ramp contraction, and it is less influenced by the contraction speed.

A seismic wave propagating in a fluid-saturated porous media, moves ions in the double layer between the fluid and solid and induces an electric field. When there is discontinuity (such as a fracture), the seismic wave induces a radiating electromagnetic (EM) wave. In this paper, we investigate seismoelectric fields in media with vertical and inclined fractures using cross-borehole measurements in the laboratory. Our laboratory results show that an acoustic source in a borehole generates a radiating EM wave at a vertical fracture, which is recorded by an electrode in the second borehole. The position of the fracture can be determined by the arrival times of the EM wave and acoustic wave, and the velocity of formation. The position of an inclined fracture between two boreholes can be determined by placing the acoustic source at a different depth and recording with real or synthetic arrays of acoustic receivers in the second borehole.

Axial compression tests have shown fiber reinforced polymer (FRP) tubes to significantly enhance both strength and ductility of concrete columns. However, most experiments and associated models typically do not account for the internal reinforcement, size effect of the column, and the end load-bearing conditions of the tube. An experimental program was undertaken to evaluate the effect of these parameters on the performance of CFFT columns. Glass FRP tubes filled with plain, steel-reinforced, and glass FRP-reinforced concrete were tested with and without end grooves, which would prevent the tube from directly bearing of the axial load. The experiments showed the dowel action of the internal reinforcement to improve the ductility of the columns by restraining the lateral dilation of concrete core. Anempirically derived confinement model, augmented with the stress-strain response of the internal reinforcement, showed close agreement with test results.