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Bamboo is highly susceptible to mold infection owing to the presence of large number of holes and rich nutrients, resulting in huge economic losses. Chemical bacteriostasis plays an effective role in mildew prevention, however it has adverse effects on the human body and environment. Nowadays, people are paying considerable attention to green and safe methods of bamboo protection. Glycerol monolaurate and phytol are natural and environmentally-friendly fungicides. In this study, a complex emulsion was prepared using phytol, glycerol monolaurate, and carnauba wax. The preparation process was studied using orthogonal experiments, and the properties of the emulsion were characterized. The emulsifier ratio was found to have a significant effect on the particle size and solid content of the emulsion. The anti-mildew property of emulsion-treated bamboo was also evaluated. The emulsion particles were deposited onto the surface and inside of the bamboo. All the contact angles of the treated bamboo were above 120° and most of the natural stacking occurred after 28 days without mildew. The anti-mildew mechanism of the complex emulsion was to combine the physical barrier of wax with the chemical inhibition of glycerol monolaurate and phytol to prevent mold infection of bamboo. The glycerol monolaurate/phytol and carnauba wax-based complex emulsion is expected to benefit the protection of bamboo products. [ABSTRACT FROM AUTHOR]

Self-bonding bamboo particleboards were prepared via hot pressing of bamboo residue fermented by lactic acid bacteria. An orthogonal experiment was designed to investigate the effects of three factors (type of lactic acid bacteria used for fermentation, moisture content (MC) of the fermented residue, and hot-pressing temperature) on the resulting selfbonding particleboards. The bending strength and internal bonding strength of the prepared self-bonding particleboards were tested. Fracture characterization was performed on the cross-section of the prepared selfbonding particleboards after bending breakage. The hot-pressing temperature, moisture content (MC), and type of lactic acid bacteria of the fermented residue had a significant effect on the mechanical strength of self-bonding particleboards, and with increased hot-pressing temperature, the strength of self-bonding particleboards increased. Analysis of the cross-sectional morphology and porosity confirmed the significant effect of hot-pressing temperature on the density distribution of self-bonding particleboards. The self-bonding particleboard produced at the hotpressing temperature of 180 °C, MC of 30%, and that used Lactobacillus plantarum as a fermentation strain showed the best overall performance and reached Chinese standard requirements for common particleboards. [ABSTRACT FROM AUTHOR]

The aim of this study was to understand the effect of ultrasonic treatment on the bonding shear strength and the microstructure of bonding interface and adhesive penetration of the laminated bamboo lumber. The ultrasonic cavitation treatment was used to increase the permeability of phenol formaldehyde (PF) adhesive in the surface of bamboo strips and the linkage between adhesive and bamboo. Bleached and carbonized bamboo strips were adopted to make two-ply laminated bamboo lumber with phenol formaldehyde adhesive. The orthogonal experiment (L9(34)) was used for evaluating the effect of ultrasonic process parameters including time, temperature and power on the shear strength of laminated bamboo lumber. The variation of the microstructure and the bond line thickness of laminated bamboo lumber were studied by scanning electron microscopy. The average penetration and the effective penetration of PF adhesive in the bamboo surface were evaluated by fluorescent microscopy characterization. The orthogonal result showed that shear strength of the laminated bamboo lumber was affected by ultrasonic temperature, power and time in turn. Temperature had a more significant effect than the other two factors. Compared with the untreated group, the shear strength of laminated bamboo lumber with bleached bamboo strips was increased by 18% and that of laminated bamboo lumber with carbonized bamboo strips was increased by 12.5% after the optimal ultrasonic treatment of bamboo strips. Ultrasonic treatment can enhance the penetration of adhesive on the bamboo surface and the bondline thickness was correspondingly increased. The effect of ultrasonic process on bleached bamboo strips is more obvious than on carbonized bamboo strips, and correspondingly the increase in PF penetration in bamboo surface of laminated bleached bamboo lumbers is more. Ultrasonic treatment on bamboo strips can enhance the bonding strength of laminated bamboo lumber and PF adhesive penetration greatly, therefore, ultrasonic treatment should be an effective method to improve the adhesion between bamboo strips. [ABSTRACT FROM AUTHOR]

Recently, research on the energy harvesting floor is attracting more and more attention due to its possible application in the smart house, invasion monitoring, internet of things, etc. This paper introduced a design and comparative study of a small-stroke piezoelectric energy harvesting floor based on a multi-layer piezoelectric beam structure. The multi-layer piezoelectric beams are designed based on simply supported beams in an interdigitated manner. Theoretical analysis is explored to find out the beam number and layer number of the structure. Through this design, the input power from the human footsteps was effectively utilized and transformed into electrical power. The designed piezoelectric energy harvesting floor structure was tested by our designed stepping machine, which can simulate the stepping effect of a walking human on the floor with different parameters such as stepping frequency. Comparative studies of the energy harvester are carried out regarding different stepping frequencies, external circuits, and initial beam shapes. The experimental results showed that the maximum output power of a group of four-layer prototypes was 960.9 µW at a stroke of 4 mm and a step frequency of 0.83 Hz, with the beams connected in parallel. [ABSTRACT FROM AUTHOR]

In this paper, we study the nonlinear dynamics of a multiplex system consisting of neuronal networks each with an arbitrary number of FitzHugh-Nagumo neurons and intra-connections and delayed couplings. The network contains an autaptic connection formed by the axon of a neuron on its own soma or dendrites. The stability and instability of the network are determined and the existence of bifurcation is discussed. Then, the study turns to validate the theoretical analysis through numerical simulations. Abundant dynamical phenomena of the network are explored, such as coexisting multi-period oscillations and chaotic responses. [ABSTRACT FROM AUTHOR]

The coupling of converters with resonant networks poses significant challenges for frequency tracking and power control in inductive power transfer (IPT) systems. This paper presents an implementation method that addresses these issues by dividing the system's operation into two distinct states: self-oscillating and power-injecting. Based on these states, a phase-closed loop is constructed. Within this closed loop, the phase tracking unit detects and tracks frequency drift, while the power regulating unit incorporates an integrator and adopts a control variable to adjust the output power by modifying the duration of the power injecting state. Meanwhile, the oscillating unit operates in the self-oscillating state. Operating in this manner, the system achieves self-oscillation and demonstrates the capability to effectively track and compensate for system variations within a single cycle. A verification prototype has been constructed, and it demonstrates that the converter within it completely decoupled from the resonant network. Experimental results validate that altering the control variable solely affects the duration of the power-injecting state, allowing for independent control of the output power. When the control variable changes from 2.0 V to 3.5 V, the output power changes from 178 W to 519 W while the self-oscillating state remains unchanged. Furthermore, the system accurately tracks frequency changes, even under significant variations in the coupling coefficient or load, without compromising the power injection state. When the air gap changes from 3 cm to 12 cm, the duration of the self-oscillating state changes from 22.1 μs to 26.3 μs, while the power injecting state remains unchanged. This approach exhibits a robust performance, particularly suitable for dynamic IPT systems sensitive to parameter variations. [ABSTRACT FROM AUTHOR]

Rotational energy harvesting technology has attracted more and more attention recently. This paper presents a piezoelectric rotational energy harvester that can be mounted with an offset distance from the rotation center. The piezoelectric energy harvester is designed to be dynamically excited by the force due to gravity, which causes the piezoelectric cantilever beams in the harvester to vibrate periodically as the harvester rotates. A novel design of the harvester structure with a hollow mass is proposed and analyzed in this paper. Experiments were performed to investigate the design and analysis. A power output of 106~2308 μW can be achieved at the rotating frequencies of 0.79~14 Hz with a piezoelectric cantilever beam in the prototyped energy harvester. Results showed that the prototyped harvester can be mounted on a rotating wheel hub and output sufficient power in a wide frequency range for wireless monitoring sensors. [ABSTRACT FROM AUTHOR]

To study the effect of the precuring rate of impregnated fluffed veneers (IFVs) on the bonding performance of scrimber, the precuring rate of IFVs following different drying conditions was characterized by fluorescence microscopy. The phenol formaldehyde (PF) solid content, drying temperature, and time were assessed using orthogonal tests. The moisture content, precuring rate of the dried IFVs, and bonding strength of the scrimber were evaluated. The results showed that the moisture content of the IFVs was mainly affected by the PF solid content, while the precuring rate of the impregnated IFVs was primarily impacted by the drying temperature. A solid PF content of 20% and optimum drying conditions of 60 °C and 1.5 h were associated with a precuring rate of 12.3% of the PF resin on the surface of the IFVs, obtaining scrimber with the best bonding performance of 2.95 MPa. [ABSTRACT FROM AUTHOR]

A series of DC power supply converters can be described as linear affine systems with finite inputs and constrained switching frequency. In this study, a practical‐stability‐oriented general control framework with duty‐cycle‐like characteristics is deduced for such converters. First, a concept called End Point Equivalence Modulation (EPEM) is introduced to release constraints. Following this, a Control Lyapunov Function (CLF) is employed to design the switching law and the relationship between the boundary of the convergence zone and the switching frequency is derived. In addition, an optimized switching strategy is presented to halve the switching frequency without degrading the control performance, which is also helpful for reducing switching loss. Finally, a single‐phase inverter and buck converter are considered as case studies and analysis show that Sinusoidal Pulse Width Modulation (SPWM) and volt‐second balance guarantee their practical stability, respectively, which can be theoretically derived and proved under EPEM. All the proposed methods and controllers are validated both by simulations on MATLAB/Simulink and experiments in a rapid control prototype platform based on a FPGA module. [ABSTRACT FROM AUTHOR]

The recycling and utilization of feather waste from animal husbandry and straw from agriculture is a worldwide problem. In this study, keratin was extracted from waste feathers and used to modify urea‐formaldehyde (UF) adhesive to obtain biodegradable adhesive for making straw flowerpots with high performance. The results showed that keratin could reduce free formaldehyde and improve the thermal stability of UF. Furthermore, the mechanical properties of the flowerpot with keratin were greatly improved. The observed performance enhancements were attributed to the excellent adhesiveness of the bonding interface. In addition, the addition of keratin makes the flowerpot more hydrophilic and provides a better source of nutrients for microbes to grow and reproduce on the surface of the flowerpot, which is more conducive to the biodegradation of flowerpots after they are discarded. Our experiment suggests the great potential in terms of profitability and environmental protection by flowerpots prepared by fermented straw fiber and keratin‐modified UF. [ABSTRACT FROM AUTHOR]

In this paper, an energy harvesting floor based on piezoelectric transducers is studied. A structure with multiple layers of piezoelectric beams is designed. Different striking frequencies are studied. Fourier transform is applied to analyze the frequency characteristic of the output voltage. Experiments are explored to find out the optimal external load resistance for maximum output power. The experimental results show that, with three piezoelectric transducers in a beam array, and a stroke of 4 mm at the striking frequency of 1.263 Hz, the maximum output power is 733.5 µW. [ABSTRACT FROM AUTHOR]

Environmentally friendly fabrication of engineered bamboo lumber is enabled by the application of renewable, formaldehyde-free bio-adhesives. In this study, protein-based adhesives made from pig blood (PB) were developed for this purpose. PB was modified by alkali (NaOH) and glutaraldehyde into either alkali-modified pig blood adhesive (APB), glutaraldehyde-modified pig blood adhesive (GPB), or alkali-and-glutaraldehyde-modified pig blood adhesive (AGPB), which were expected to be more water-resistant. Two-ply laminated bamboo lumber samples were assembled, and their bonding strengths were measured. The thermal properties, presence of functional groups, and cross-sectional micro-morphologies of the modified adhesives and unmodified PB were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The thermal stabilities of all the modified adhesives were improved compared to that of the unmodified PB. FTIR confirmed that the NaOH treatment successfully induced the unfolding of the PB protein, exposing the hydrophobic groups in the APB and that glutaraldehyde became grafted onto primary amides in the AGPB. Compared with the PB and APB, the cross-sectional micro-morphologies of the GPB and AGPB were more homogeneous and compact. The wet shear strength of the laminated bamboo lumber (LBL) was clearly increased by the modified adhesives. The AGPB had a higher wet shear strength of 4.6 MPa. Thus, the GPB and AGPB can be considered as potential protein adhesives for use in a variety of engineered bamboo products. [ABSTRACT FROM AUTHOR]

To investigate the influence of the drying process on the bonding properties of laminated wood, a poplar veneer was impregnated with low molecular-weight phenol formaldehyde (PF) resin and laminated wood was created and studied. The effects of drying temperature, drying time and solid content of the PF resin on the moisture content (MC) of the impregnated veneer after drying and the shear strength of the laminated wood were analyzed with an orthogonal experiment. The microscopic mechanism of the bonding performance of the laminated woods was investigated by fluorescence microscopy. The experimental results showed that the higher the PF resin solid content was, the larger the weight gain percentage of the impregnated veneer was. In addition to drying temperature and drying time, the solid content of PF also had a significant influence on the MC of the impregnated veneer after drying. The shear strength of the laminated wood affected by the drying temperature, solid content of PF and drying time and the drying temperature had a more significant effect than the other two factors. The best drying process was a drying temperature of 50 °C, a drying time of 2 h, and a PF solid content of 30%. The fluorescence analysis showed that the shear strength of the laminated wood was affected by the intensity of the PF resin on the bonding interface, and the average and effective penetration depth of the PF resin in the veneer increased with the increase in the drying temperature. [ABSTRACT FROM AUTHOR]

The failure of composite materials during bending is an issue that must be considered in the performance evaluation of structural materials. Strong–weak interlaminated composites are particularly prone to weak interfaces. In this study, the digital image correlation (DIC) method is used to detect the strain distribution of high-performance carbon fiber-reinforced eucalyptus/poplar composite plywood under three-point bending. Finite element analysis (FEA) method is used to numerically simulate the composite plywood of each reinforced structure, and failure evaluation in the bent state of plywood is carried out. Testing is then undertaken to determine that the FEA simulated value and the DIC measured value fit well. Besides, bending test verifies the failure mode predicted by FEA, which will be a very good prediction method for material failure. [ABSTRACT FROM AUTHOR]

Lightweight automobiles urgently need a kind of high strength lightweight structure carriage floor. In this study, a carbon fiber fabric/poplar/eucalyptus composite plywood for carriage floors was prepared by designing different structures of low-strength, fast-growing poplar veneer, eucalyptus veneer, and high-performance carbon fiber fabric. The mechanical properties, thermal insulation, and sound insulation of the composite plywood were evaluated. Results indicated that the composite plywood had a density of less than 0.7 g/cm3. In addition, the 24 h water absorption rate and the 24 h thickness swelling rate of the composite plywood were markedly reduced after the surface was reinforced with the carbon fiber fabric. The core-reinforced group showed large increases in bond strength, screw holding capability, and thermal insulation performance. The carbon fiber fabric-reinforced plywood showed improvement in stability and sound insulation performance in high-frequency bands. The carbon fiber fabric-reinforced plywood is a low-cost, high-strength, lightweight floor alternative. [ABSTRACT FROM AUTHOR]

Harvesting energy from human motions for powering portable or wearable electronic devices is attracting attentions in recent years. In this paper, an inertial energy harvester based on a piezoelectric cantilever beam is investigated for harvesting energy from a backpack. Vibration levels in the backpack during walking or jogging were tested and analyzed. Theoretical analysis was explored to determine parameters of the harvester. The generated power of the cantilever beam was experimentally studied. The experimental results show that the harvester can achieve a power output of 43.64 μW with a single piezoelectric element. [ABSTRACT FROM AUTHOR]

This paper presents an energy harvesting system targeted to harness energy from a high internal resistance thermoelectric generator (TEG) under low temperature difference condition. The system is based on a DC–DC boost converter with a maximum power point tracking scheme. An optimal current control scheme and zero current switching technique are applied for low power consumption and high efficiency. An analysis on power losses of the system is performed. A prototype system is built to show the performance and to verify the theoretical analysis. Experimental results show that the proposed system can harvest enough power to run a wireless sensor node at a transmission cycle of 30 s with a minimum input power of 27 μW and a low temperature difference of 1.9 K across the TEG. The peak efficiency of the power conversion can reach 75.2% in the considered input voltage range. [ABSTRACT FROM AUTHOR]

An adaptive energy harvesting system for high voltage piezoelectric generators is presented in this paper. Maximum power point tracking scheme is applied in the adaptive system. Low-power-consumption schemes are applied in the control system and harvesting circuit. A self-startup circuit is also applied to the system. Theoretical analysis was explored to determine optimal parameters for the harvesting system. Experiments were done to verify the theoretical analysis. The experimental results show that the harvesting system can achieve an efficiency of 17.5 ∼ 73.3% for piezoelectric generator with a peak open-circuit voltage of 6 ∼ 20 V. And the harvesting system can be self-powered from low input power as 25 μW. The average power consumption of the microcontroller can be low as 3.5 μW. [ABSTRACT FROM AUTHOR]

The objective of this research was to comprehensively compare the effects of nanoclay bentonite (BT), halloysite nanotubes (HNTs) and sulfuric acid-etched halloysite nanotubes on the surface wettability, morphological, mechanical and thermal properties of cellulose nanofibril (CNF) biocomposites. A simple and environmental safe casting-evaporation method was used to fabricate these samples, which comprised up to 10 wt% of nanoclay. The surface wettability, tensile testing and TG results showed that the biocomposites with BT exhibited greater hydrophobicity, larger modulus and strength and better thermal stability than with HNTs at low content. However, at high content, the biocomposites with HNTs exhibited larger elongation at break. The DMA results indicated that biocomposites with HNTs exhibited better molecular motion restriction than with BT. These results combined with Fourier Transform Infrared (FTIR) also indicated interfacial interactions between CNF matrix and nanoclay. Acid treatment would help promote the interfacial interactions between HNTs and CNFs, resulting in enhanced mechanical and thermal properties. This comparative study will help in the choice of appropriate nanoclay for use in functional biomaterials in industrial production applications. [ABSTRACT FROM AUTHOR]

ABSTRACT We undertook this study to understand reinforcement mechanism of short cellulose nanocrystals (CNCs) and long cellulose nanofibrils (CNFs) as compatibility agents for improving the interfacial miscibility of poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) blends. The effects of the two cellulose nanofibers on the morphological, mechanical, and thermal properties of the polymer blends were compared systematically. The light transparency, scanning electron microscopy, and Fourier transform infrared results show that nanocellulose between PVA and PEO eliminated the negative effects generated by the immiscible interface through increased hydrogen bonding. Thermogravimetric analysis and differential scanning calorimetry results show that crystalline region reorganization around the interface facilitated the shift of the polymer blends from multiple phases to a homogeneous phase. According to the Halpin-Kardos and Quali models, we assumed that the potential for repairing the immiscible interface would have a larger effect than the potential of reinforcement. At the same concentration, polymer blends with CNCs showed greater light transparency, strength, modulus, and crystal structure than with those with CNFs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45896. [ABSTRACT FROM AUTHOR]

Using thermoelectric elements to harvest energy from heat has been of great interest during the last decade. This paper presents a direct current-direct current (DC-DC) boost converter with a maximum power point tracking (MPPT) scheme for low input voltage thermoelectric energy harvesting applications. Zero current switch technique is applied in the proposed MPPT scheme. Theoretical analysis on the converter circuits is explored to derive the equations for parameters needed in the design of the boost converter. Simulations and experiments are carried out to verify the theoretical analysis and equations. A prototype of the designed converter is built using discrete components and a low-power microcontroller. The results show that the designed converter can achieve a high efficiency at low input voltage. The experimental efficiency of the designed converter is compared with a commercial converter solution. It is shown that the designed converter has a higher efficiency than the commercial solution in the considered voltage range. [ABSTRACT FROM AUTHOR]

This paper presents a two-stage adaptive boost converter with low-voltage starter for low voltage piezoelectric energy harvester. The adaptive technique can deal with a range of input voltages from the piezoelectric generator for required output voltages. The parameters of the converter including inductance, switching frequency, duty cycles and the input/output voltage are studied for conversion efficiencies. The experiment results show that a two-stage adaptive boost converter can achieve a conversion efficiency of 84.3%∼91.3% for a piezoelectric harvester in the considered low voltage range to charge an 1.5Venergy storage device. [ABSTRACT FROM AUTHOR]

This work proposes a novel frequency tunable mechanism for piezoelectric harvester system. The piezoelectric harvester is constructed by a cantilever base beam and piezoelectric elements coupled with the base beam in a certain manner. By modifying the electrical boundary conditions of the piezoelectric elements, the resonant frequency of the composite beam structure changes accordingly. Two kinds of coupling modes, d31 mode and d33 mode, were investigated and verified with simulations and experiments. The results showed that the d33 mode surpassed the d31 mode with a resonant frequency variation ratio of 28.59%. [ABSTRACT FROM AUTHOR]

Powering the distributed or embedded wireless sensors from ambient vibration energy has attracted many attentions. It will reduce the installment trouble and maintenance costs. This work reports on vibration levels detected in automobiles during road test as a potential energy source for automobile sensors. A piezoelectric vibration harvester was designed and equipped with a simple harvesting circuit. The measurement results showed that the vibrations in the automobiles are large enough to possibly supply a wireless sensor. [ABSTRACT FROM PUBLISHER]

ABSTRACT The study of the shear strain distribution at the bonding interface helped us to understand the bamboo bonding interface response mechanisms to solve problems of ply bamboo deformation or bonding failure. The shear strain distribution across a two-ply bamboo sheet bonded with a ductile phenol-formaldehyde resin (PF) modified by poly(vinyl alcohol) (PVA) was measured by means of electronic speckle pattern interferometry, along with tensile strength measurements to prove the shear stain distribution on a macroscopic scale. This research effectively combined macroscopic mechanical properties with microcosmic interfacial mechanical properties. The shear strength and shear strain results showed that PF modified with 20% PVA performed better than common PF and PF modified with 5 and 10% PVA. Microscopic fluorescent characterization of the bonding interface also provided evidence that a new bonding mechanism was adequate for bamboo bonding under the ductile PF modified with 20% PVA. Moreover, we suppose that the results of this study will help in the choice of bamboo-specific adhesives under different strain conditions. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1345-1350, 2013 [ABSTRACT FROM AUTHOR]

Dynamic properties of bamboo, Phyllostachys pubescens, with moisture content (MC) ranging from −130 to 130°C, were studied by dynamic mechanical analysis (DMA). The results showed that the hygrothermal effect on dynamic mechanical properties was negative. The storage modulus decreases with increasing temperature and MC, and glass transition temperature decreases with increasing MC. The glass transition temperature and tan delta of bamboo were 30.5°C, 0.02 and 10.61°C, 0.04, when MC was 10% and 34%, respectively. [ABSTRACT FROM AUTHOR]

An automatic stage transition converter for an inductive power transfer system is presented in this paper. An effective control strategy with two working stages of independent energy injection stage and free resonance stage is employed in the proposed converter. With the automatic stage transition strategy, when the frequency of the resonance network changes, the ending time of the free resonance stage is automatically determined. At the same time, the phase angle of the free resonance stage is automatically set as half a resonant cycle. As the stage transition is not triggered by the switches, the switch motion can be executed in advance of the transition moments. Time margins are offered for every switch in the converter, which make the switching moments of the switches flexible and the control simple. Another feature of this converter is that during the energy injection stage, the energy is injected into the inductor independently. Therefore, the input power can be easily regulated by adjusting the energy injection time. A prototype for the converter and the inductive power transfer system was implemented experimentally. From the experimental results, the automatic stage transition and power regulation capability of the proposed converter are verified. The switches all operated at the soft switch condition. When the energy injection time was adjusted from 10 μs to 25 μs, the output power changed from 143 W to 740 W. [ABSTRACT FROM AUTHOR]

Bamboo shoot shell fibers (BSSFs)/starch/poly(lactic acid) (PLA) ternary composites were prepared by blending BSSFs to starch/PLA matrices for the purpose of expanding BSSFs applications to enhance starch/PLA composites and creating a new low‐cost biodegradable composite. The effects of BSSFs content (0–40 wt %) on the physical–mechanical properties were tested and interface compatibility and its mechanism to mechanical performance of BSSFs/starch/PLA composites were characterized by SEM‐EDS, TG. The results showed that the mechanical strength, surface wettability, and water absorption of the composites continued improving when the BSSFs content increased from 0% to 20 wt %. However, mechanical modulus increased with increase in BSSFs content. The results of fracture microstructure and thermal property exhibited a good interfacial compatibility at low content of BSSFs and an interface debonding at high content of BSSFs. These investigations indicated that the BSSFs reinforcement to the composite is not consistent with interface compatibility of the ternary composites. The composites should be considered as a kind of green and low‐cost biodegradable materials to replace traditional single‐phase or multiphase materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47899. [ABSTRACT FROM AUTHOR]

This paper proposes a novel energy harvesting floor structure using piezoelectric elements for converting energy from human steps into electricity. The piezoelectric energy harvesting structure was constructed by a force amplification mechanism and a double-layer squeezing structure in which piezoelectric beams were deployed. The generated electrical voltage and output power were investigated in practical conditions under different strokes and step frequencies. The maximum peak-to-peak voltage was found to be 51.2 V at a stroke of 5 mm and a step frequency of 1.81 Hz. In addition, the corresponding output power for a single piezoelectric beam was tested to be 134.2 μW, demonstrating the potential of harvesting energy from the pedestrians for powering low-power electronic devices. [ABSTRACT FROM AUTHOR]

Strong coupling in an inductive power transfer (IPT) system will lead to difficulties in power control and loss of soft switching conditions. This paper presents an IPT system that can decouple the converter from the resonant network. In the proposed system, the energy transmission process is divided into energy injection stage and free resonance stage. In the energy injection stage, the inductor is separated from the resonance network, and the power source injects energy into the inductor independently. In the free resonance stage, the inductor is connected to the resonance network for resonating. As a benefit from the decoupling of the converter from the resonance network, the proposed IPT system is characterized by easy power control and soft switching operation. A prototype was built for experiments. The experimental results show that with a supply voltage of 300 V, coupling factor of 0.2, and load resistance of 10 Ω, the output power can be controlled nearly linearly by the time of the energy injection stage in a range of 40–60 μs, and the system works under soft switching conditions. [ABSTRACT FROM AUTHOR]

This paper presents a study of a piezoelectric energy harvesting circuit based on low-power-consumption synchronized switch technology. The proposed circuit includes a parallel synchronized switch harvesting on inductor interface circuit (P-SSHI) and a step-down DC-DC converter. The synchronized switch technology is applied to increase the conversion efficiency of the circuit. The DC-DC converter is used to accomplish the impedance matching for different loads. A low-power-consumption microcontroller and discrete components are used to build the P-SSHI interface circuit. The study starts with theoretical analysis and simulations of the P-SSHI interface circuit. Simulations and experiments were conducted to validate the theoretical analysis. The experimental results show that the maximum energy harvested by the system with a P-SSHI interface circuit is 231 μW, which is 2.89 times that of a system without the P-SSHI scheme. The power consumption of the P-SSHI interface circuit can be as low as 10.6 μW. [ABSTRACT FROM AUTHOR]

In order to compensate the large leakage inductance and improve the power transmission capacity, capacitors are widely used in inductive power transfer (IPT) systems, which results in high voltage or current stresses in the resonant tanks and limits higher volt-ampere (VA) rating of the transfer power, especially in medium and low frequency applications. This paper presents a symmetrical half-bridge resonant converter (SHRC) for series-series/series compensated IPT systems with detailed analysis and design. It operates at a relatively low frequency of 12.5 kHz, suitable for IGBT applications. The theoretical analysis shows that, compared with full-bridge resonant converter (FRC) for IPT, the symmetrical half-bridge resonant converter achieves a higher efficiency. Simulation and a prototype of 1500 W power output were built to verify the theoretical analysis. The experimental results show that the power loss of SHRC is 39.7 W while that of FRC is 79.4 W, which is consistent with the theoretical analysis. The global efficiency of the IPT based on the proposed converter is 91.6%. [ABSTRACT FROM AUTHOR]

In a traditional inductive coupling power transfer (ICPT) system, the converter and the resonant network are strongly coupled. Since the coupling coefficient and the parameters of the resonant network usually vary, the resonant network easily detunes, and the system efficiency, power source capacity, power control, and soft switching conditions of the ICPT system are considerably affected. This paper presents an ICPT system based on a power converter decoupled from the resonant network. In the proposed system, the primary inductor is disconnected from the resonant network during the energy injection stage. After storing a certain amount of energy, the primary inductor is reconnects with the resonant network. Through this method, the converter can be decoupled from the resonant network, and the resonant network can be tuned under various coupling coefficients. Theoretical analysis was explored first. Simulations and experimental work are carried out to verify the theoretical analysis. The results show that the proposed ICPT system has the virtues of low power source capacity, independent power control, and soft switching operation under different coupling coefficients. [ABSTRACT FROM AUTHOR]