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Harvesting vibration energy to power wearable devices has become a hot research topic, while the output power and conversion efficiency of a vibration energy harvester with a single electromechanical conversion mechanism is low and the working frequency band and load range are narrow. In this paper, a new structure of piezoelectric electromagnetic coupling up-conversion multi-directional vibration energy harvester is proposed. Four piezoelectric electromagnetic coupling cantilever beams are installed on the axis of the base along the circumferential direction. Piezoelectric plates are set on the surface of each cantilever beam to harvest energy. The permanent magnet on the beam is placed on the free end of the cantilever beam as a mass block. Four coils for collecting energy are arranged on the base under the permanent magnets on the cantilever beams. A bearing is installed on the central shaft of the base and a rotating mass block is arranged on the outer ring of the bearing. Four permanent magnets are arranged on the rotating mass block and their positions correspond to the permanent magnets on the cantilever beams. The piezoelectric cantilever is induced to vibrate at its natural frequency by the interaction between the magnet on cantilever and the magnets on the rotating mass block. It can collect the nonlinear impact vibration energy of low-frequency motion to meet the energy harvesting of human motion.

Among electric vehicle charging technologies, wireless charging technology is undoubtedly a most convenient method, also needless to get refreshed and repaired as wires do. Nevertheless, it has long been a tough issue that the efficiency remains low, which causes great waste and too much heat even add to the possibility of fire emergency. Due to low charging efficiency and non-universal charging equipment, wireless charging equipment for electric vehicles has not been effectively promoted. Based on this, integrated circuit theory and electromagnetic field equation, this paper established electromagnetic coupling wireless charging circuit model, based on this model, the maximum wireless charging power transmission efficiency and the maximum horizontal offset and other issues are studied.

The magnetic signatures of ocean \\[\\hbox {M}_{2}\\] tides have been successfully detected by the low-orbit satellite missions CHAMP and Swarm. They have been also used to constrain the electrical conductivity in the uppermost regions of the Earth’s mantle. Here, we concentrate on the problem of accurate numerical modelling of tidally induced magnetic field, using two different three-dimensional approaches: the contraction integral equation method and the spherical harmonic-finite element method. In particular, we discuss the effects of numerical resolution, self-induction, the galvanic and inductive coupling between the oceans and the underlying mantle. We also study the applicability of a simplified two-dimensional approximation, where the ocean is approximated by a single layer with vertically averaged conductivity and tidal forcing. We demonstrate that the two-dimensional approach is sufficient to predict the large-scale tidal signals observable on the satellite altitude. However, for accurate predictions of \\[\\hbox {M}_{2}\\] tidal signals in the areas with significant variations of bathymetry, and close to the coastlines, full three-dimensional calculations are required. The ocean–mantle electromagnetic coupling has to be treated in the full complexity, including the toroidal magnetic field generated by the vertical currents flowing from and into the mantle.

Electromagnetic coupling treatment (EMCT) is a new method to regulate material properties. To investigate the effect of EMCT on the plasticity of the Al-Cu-Mg alloy, a software simulation calculation was carried out, and then the alloy was treated with an electromagnetic field, and its mechanical properties were tested at room temperature. The simulation results reveal that the sample generates a plastic strain of 6.88*10 3 ppm, potentially enhancing its tensile properties. The experimental findings indicate that EMCT did not have a substantial impact on the strength and hardness of the aluminum alloy. However, it did result in a 16.9% increase in the sample’s plasticity and a 5.6% drop in the elastic modulus

The effective extension of tool life while maintaining machining quality is an important research topic in advanced machining and sustainable manufacturing. Cemented carbide is widely used as the tool material in different manufacturing processes, and it has various forms and work ranges. However, the internal flaw in the tool material can induce a micro-crack which could result in the decrease of tool strength and toughness, and affect the tool life. Improving the tool cutting performance, slowing down the tool wear, and enhancing production efficiency are the eternal themes of cutting tool research. This research focused on a P10 cemented carbide tool. The influences of the electromagnetic coupling field (TEMCP) on the carbide tool life and the maximum of tool force are investigated. The correlation analysis between the TEMCP parameters and the tool life index is conducted using SPSS. The experiment proves that the TEMCP can significantly prolong the cemented carbide tool life, and that the magnetic intensity is a dominant factor. The TEMCP enriches the field technology theory and provides technical support for the sustainable manufacturing and research and development of a high-performance tool with important scientific meaning and research potential.

Recently, the reaction speed and cycle performance of hexavalent chromium reduction over microsized zero-valent iron (ZVI) with an Fe 0 core and iron oxide (FeO x ) shell structure have been improved by activating the Fe 0 -core electrons through electromagnetic coupling between Fe 0 -core electrons and charges (hexavalent chromium in solution, double-charge layers of the ZVI/solution interface). Herein, the abovementioned electromagnetic coupling was greatly increased by adding salt (CH 3 COONa, NaCl, NaNO 3 , and Na 2 SO 4 ) in the hexavalent chromium solution to increase the charge response. Adding salt greatly improved the reaction speed and cycle performance of hexavalent chromium reduction. It took 8 min to reduce hexavalent chromium with CH 3 COONa to below the discharge standard of wastewater in the first cycle and 20 min after reducing for 20 cycles. The best apparent rate of constant value (0.416 (min) -1 ) is nearly four times larger than those without salts. X-ray diffraction and X-ray photoelectron spectroscopy revealed the production of amorphous iron oxide shell with salt. The salt improves the hexavalent chromium reduction speed and cycle performance and impedes the Fe 0 -core-electron transfer via the produced Fe 2 O 3 , resulting in existence of an optimized salt dosage. This work aims to provide an effective route for enhancing the removal efficiency and cycle performance of heavy-metal–ion reduction via Fe 0 . And this work also proposes a novel viewpoint that adding salt in waste water would increase the electromagnetic coupling between the charges in solution and Fe 0 -core electrons which could finally activate the redox reaction.

A capacitor modeled as a parallel combination of a resistance (R) and a capacitance (C) exhibits three distinct operating regimes when both parameters depend on the applied voltage (V): a positive-capacitance regime (dR/R>dV/V), an Ohmic regime (dR/R=dV/V), and a negative-capacitance regime (dR/R

Journal Article

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