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In order to solve the problem of conventional energy shortages, a non-resonant impact piezoelectric energy capture device using a (polyvinylidene fluoride) piezoelectric film at low frequency is proposed, and related theoretical analysis and experimental studies are conducted. The device has a simple internal structure, is green and easy to miniaturize, and is capable of harvesting energy at low frequencies to supply energy to micro and small electronic devices. First, to verify the feasibility of the device, the structure of the experimental device is modeled and dynamically analyzed. Then the modal, stress–strain, and output voltage of the piezoelectric film are simulated and analyzed using COMSOL Multiphysics simulation software. Finally, the experimental prototype is built according to the model, and the experimental platform is constructed to test the relevant performance. The experimental results show that the output power produced by the capturer varies within a certain range when the capturer is excited externally. With an external excitation force of 30 N, a piezoelectric film bending amplitude of 60°, and a piezoelectric film size of 45 × 80 mm, the resulting output power voltage is 21.69 V, the output current is 0.07 mA, and the output power is 1.5176 mW. This experiment verifies the feasibility of the energy capturer and provides a new idea for powering electronic components. [ABSTRACT FROM AUTHOR]

Fiber-reinforced flexible pipes are subjected to large axial tension loads in deep-water applications, which may result in the excessive deformation of the pipes. Owing to the anisotropy of the composite materials, accurately describing the tensile behavior of these pipes is difficult. Theoretical, numerical, and experimental methods are employed in this study to investigate the mechanical characteristics of a glass fiber-reinforced unbonded flexible pipe under axial tensile loads. Based on the load–strain relationship of each pipe layer, analytical equations considering the effect of anisotropy and radial deformation are first proposed to calculate the axial tensile stiffness of the pipe. A detailed numerical model is established to simulate the tensile behavior of the pipe. A prototype test is performed on a 4500 mm long sample using a tensile testing machine. The leading roles of outer tensile reinforcement layers in axial tensile capacity are illustrated by the strain energy of the pipe layers obtained by the numerical model. Subsequently, a comparison analysis of the mean fiber direction strains of the selected sections are performed between numerical and experimental results, which validates the numerical model. Additionally, the stress distributions of different pipe layers are discussed based on the results of the numerical analysis. Finally, the comparison of axial tensile stiffness results validates the accuracy of the analytical model considering radial deformation. This study proposes effective theoretical and numerical models to predict the tensile behavior of a fiber-reinforced flexible pipe, which provides useful references for the design and structural analysis of these pipes. [ABSTRACT FROM AUTHOR]

In this work, a visual colorimetric method for the rapid and selective detection of triacetone triperoxide is reported. This visual colorimetric method is based on the reaction between potassium titanyl oxalate and hydrogen peroxide (H2O2) released from triacetone triperoxide degradation. Potassium titanyl oxalate can selectively react with H2O2 to form peroxo-titanic acid (an orange complex), enabling the colorimetric detection of triacetone triperoxide. Based on the theory that triacetone triperoxide produces hydrogen peroxide under acidic conditions, acid types, acid concentration, response time, visual limit of detection, and reactants ratio are systematically studied simultaneously for this colorimetric method. Under sulfuric acid concentration is 60%, the proposed method can almost detect triacetone triperoxide instantly, and the color of the solution reaches the maximum within 1 min and remains stable with a visual limit of detection as low as 3.0 × 10−5 mol/L. Interference experiments were carried out on other kinds of explosives (hexamethylene triperoxide diamine, trinitrotoluene, etc.). The use of colorimetric card brings great convenience to the rapid, qualitative, and semi-quantitative on-site detection of triacetone triperoxide. Because of its rapidity, high sensitivity, simplicity, and selectivity, the proposed visual colorimetric method can serve as a valuable and promising reference for triacetone triperoxide's rapid, qualitative on-site detection. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries (ZIBs) have received widespread attention. Due to serious corrosion of Zn anodes and dendrite growth, further application of ZIBs is hindered. Herein, an artificial mixed electronic–ionic conductive coating layer (Alg-Zn + AB@Zn) consisting of zinc alginate gel (Alg-Zn) and acidified conductive carbon black (AB) is introduced on the surface of Zn. The as-prepared mixed coating not only provides more Zn nucleation sites, but also effectively reduces the nucleation overpotential of Zn. Therefore, the Alg-Zn + AB@Zn symmetrical cell can stably maintain an extremely low voltage hysteresis. Furthermore, Alg-Zn + AB@Zn endows the Zn/AC full cell with excellent cycle stability, especially at high current densities. A capacity retention rate of nearly 100% can be achieved over 10 000 cycles at 10 A g−1, and 16 000 cycles at 20 A g−1, superior to those of the other reported Zn/AC full cells at high current densities, to the best of the authors' knowledge. [ABSTRACT FROM AUTHOR]

The catenary riser such as steel catenary riser (SCR), under wave action or current action, shows a kind of rotation that acts as a rigid body along a similarly fixed axis of oscillation determined by the varying suspension and touch down point, respectively. The characteristics of acceleration of catenary riser influenced by rigid body swing integrity backwards and forwards (RBSIBF) in cross direction cannot be neglected. Based on the large deflection slender beam model, top motion of x direction, RBSIBF, and wave force model, this manuscript studies and explains effect of RBSIBF in cross direction (z direction) on riser in quantitative and qualitative perspectives. The rigid body wiggle effect can be considered by amplitude-value multiplication with the safety factor of 1.2. The calculation shows that, in terms of the overall motion pattern, the motion response in the xy plane develops gradually from the narrow amplitude wiggle in in-line direction of top region to narrow amplitude wiggle in vertical direction of bottom area. Wave load is the main effect load in cross-flow direction. Along the depth increase, the acceleration amplitude of the top hanging point area is maximum, and the amplitude decreases most strongly or violently. With the decrease of case amplitude, the structural acceleration responses of node 10th to 80th significantly reduced by about 30% and the corresponding of node 140th to 200th increased by about 15%. The most influential point of RBSIBF on acceleration is node 200th with an influence level of about 20%. When the structure mainly rotates in the xz plane, rigid body wiggle and swing are positively correlated with rotation vector diameter. The rigid body wiggle and swing increase acceleration of structure. In the rotational yz plane of the structure, rigid body wiggle and swing reduce acceleration response. [ABSTRACT FROM AUTHOR]

In violent vehicular crimes, the damaged area of a vehicle is usually repainted artificially in order to conceal the evidence. Detecting and recovering the hidden sub-layer morphology of repainted automotive paint is highly valuable for providing trace evidence in hit-and-run cases. Optical coherence tomography (OCT) is a novel forensic imaging technique for repainted automotive paint analysis with the advantages of non-destructive, noncontact, high-resolution and cross-sectional imaging. In this study, we applied a custom-built spectral-domain OCT configuration with ~6 μm axial and lateral resolution to obtain three-dimensional (3D) images of an artificially prepared, internally-damaged, repainted automotive paint surface. Two-dimensional (2D) cross-sectional images were produced to locate the damaged area and 3D-OCT reconstruction was performed to directly visualize the sub-layers beneath the repainted paint surface. The results demonstrate that 3D-OCT technology manages to recover high-resolution sub-layer images of the repainted automotive paint through volumetric imaging, and thus provides more valuable information for forensic purposes. [ABSTRACT FROM AUTHOR]

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Interactions induced by dopants in a lamellar phase constructed from the lecithin and water are analyzed by the small angle x-ray scattering (SAXS) technique. From SAXS patterns, scattering peak or curve shape changes disclose information on phase structure as well as the interactions between dopant and host matrices. At a certain concentration, two amphiphilic tri-block copolymers (Pluronic P123 and F127) as dopants squeeze themselves into the lecithin bilayers with PPO hydrophobic blocks and produce various effects on the lamellar phase depending on the length of PEO hydrophilic groups. Coexistence of two different lamellar phases is observed in P123-doped systems. [ABSTRACT FROM AUTHOR]