MIL-101(Cr)is a promising moisture absorbent for solar-driven water harvesting from moisture to tackle the worldwide water shortage issue.However,the MIL-101(Cr)powder suffers from a long ab/desorption cycle due to th...MIL-101(Cr)is a promising moisture absorbent for solar-driven water harvesting from moisture to tackle the worldwide water shortage issue.However,the MIL-101(Cr)powder suffers from a long ab/desorption cycle due to the crystal aggregation caused by its inherent powder properties.Here,we demonstrate a MIL-101(Cr)nanofibrous composite membrane with a nanofibrous matrix where MIL-101(Cr)is monodisperse in the 3D porous nanofibrous matrix through a simple spray-electrospinning strategy.The continuous porous nanofibrous matrix not only offers sufficient sites for MIL-101(Cr)loading but also provides rapid moisture transport channels,resulting in a super-rapid ab/desorption duration of 50 min(including an absorption process for 40 min and a desorption process for 10 min)and multicycle daily water production of 15.9 L kg^(−1) d^(−1).Besides,the MIL-101(Cr)nanofibrous composite membrane establishes a high solar absorption of 92.8%,and excellent photothermal conversion with the surface temperature of 70.7°C under one-sun irradiation.In addition,the MIL-101(Cr)nanofibrous composite membrane shows excellent potential for practical application due to its flexibility,portability,and use stability.This work provides a new perspective of shortening MOF ab/desorption duration by introducing a porous nanofibrous matrix to improve the specific water production for the solar-driven ab/desorption water harvesting technique.展开更多
Agronomic measures are the key to promote the sustainable development of ratoon rice by reducing the damage from mechanical crushing to the residual stubble of the main crop, thereby mitigating the impact on axillary ...Agronomic measures are the key to promote the sustainable development of ratoon rice by reducing the damage from mechanical crushing to the residual stubble of the main crop, thereby mitigating the impact on axillary bud sprouting and yield formation in ratoon rice. This study used widely recommended conventional rice Jiafuzhan and hybrid rice Yongyou 2640 as the test materials to conduct a four-factor block design field experiment in a greenhouse of the experimental farm of Fujian Agricultural and Forestry University, China from 2018 to 2019.The treatments included fertilization and no fertilization, alternate wetting and drying irrigation and continuous water flooding irrigation, and plots with and without artificial crushing damage on the rice stubble. At the same time, a 13C stable isotope in-situ detection technology was used to fertilize the pot experiment. The results showed significant interactions among varieties, water management, nitrogen application and stubble status.Relative to the long-term water flooding treatment, the treatment with sequential application of nitrogen fertilizer coupled with moderate field drought for root-vigor and tiller promotion before and after harvesting of the main crop, significantly improved the effective tillers from low position nodes. This in turn increased the effective panicles per plant and grains per panicle by reducing the influence of artificial crushing damage on rice stubble and achieving a high yield of the regenerated rice. Furthermore, the partitioning of 13C assimilates to the residual stubble and its axillary buds were significantly improved at the mature stage of the main crop, while the translocation rate to roots and rhizosphere soil was reduced at the later growth stage of ratooning season rice. This was triggered by the metabolism of hormones and polyamines at the stem base regulated by the interaction of water and fertilizer at this time. We therefore suggest that to achieve a high yield of ratoon rice with low stubble height under mechanized harvesting, the timely application of nitrogen fertilizer is fundamental,coupled with moderate field drying for root-vigor preservation and tiller promotion before and after the mechanical harvesting of the main crop.展开更多
Herein,we report the design,fabrication,and performance of two wireless energy harvesting devices based on highly flexible graphene macroscopic films(FGMFs).We first demonstrate that benefiting from the high conductiv...Herein,we report the design,fabrication,and performance of two wireless energy harvesting devices based on highly flexible graphene macroscopic films(FGMFs).We first demonstrate that benefiting from the high conductivity of up to 1×10^(6)S m^(-1)and good resistive stability of FGMFs even under extensive bending,the FGMFs-based rectifying circuit(GRC)exhibits good flexibility and RF-to-DC efficiency of 53%at 2.1 GHz.Moreover,we further expand the application of FGMFs to a flexible wideband monopole rectenna and a 2.45 GHz wearable rectenna for harvesting wireless energy.The wideband rectenna at various bending conditions produces a maximum conversion efficiency of 52%,46%,and 44%at the 5th Generation(5G)2.1 GHz,Industrial Long-Term Evolution(LTE)2.3 GHz,and Scientific Medical(ISM)2.45 GHz,respectively.A 2.45 GHz GRC is optimized and integrated with an AMC-backed wearable antenna.The proposed 2.45 GHz wearable rectenna shows a maximum conversion efficiency of 55.7%.All the results indicate that the highly flexible graphene-film-based rectennas have great potential as a wireless power supplier for smart Internet of Things(loT)applications.展开更多
Energy limitation of traditional Wireless Sensor Networks(WSNs)greatly confines the network lifetime due to generating and processing massive sensing data with a limited battery.The energy harvesting WSN is a novel ne...Energy limitation of traditional Wireless Sensor Networks(WSNs)greatly confines the network lifetime due to generating and processing massive sensing data with a limited battery.The energy harvesting WSN is a novel network architecture to address the limitation of traditional WSN.However,existing coverage and deployment schemes neglect the environmental correlation of sensor nodes and external energy with respect to physical space.Comprehensively considering the spatial correlation of the environment and the uneven distribution of energy in energy harvesting WSN,we investigate how to deploy a collection of sensor nodes to save the deployment cost while ensuring the target perpetual coverage.The Confident Information Coverage(CIC)model is adopted to formulate the CIC Minimum Deployment Cost Target Perpetual Coverage(CICMTP)problem to minimize the deployed sensor nodes.As the CICMTP is NP-hard,we devise two approximation algorithms named Local Greedy Threshold Algorithm based on CIC(LGTA-CIC)and Overall Greedy Search Algorithm based on CIC(OGSA-CIC).The LGTA-CIC has a low time complexity and the OGSA-CIC has a better approximation rate.Extensive simulation results demonstrate that the OGSA-CIC is able to achieve lower deployment cost and the performance of the proposed algorithms outperforms GRNP,TPNP and EENP algorithms.展开更多
The kiwifruit trees(Actinidia deliciosa cv.Bruno)were sprayed with 5 mmol L-1 oxalic acid(OA)or water(as control)at 130,137 or 144 d after full-blossom,and then the fruit were harvested at commercial maturity and stor...The kiwifruit trees(Actinidia deliciosa cv.Bruno)were sprayed with 5 mmol L-1 oxalic acid(OA)or water(as control)at 130,137 or 144 d after full-blossom,and then the fruit were harvested at commercial maturity and stored at room temperature(20±1)℃ for 13 d.The effect of pre-harvest spraying of OA on postharvest quality of kiwifruit was evaluated during storage.The OA spraying slowed the increase in soluble solids content(SSC)and decrease in titratable acid(TA),as well as increased contents of ascorbic acid(AsA)and total-AsA accompanied with higher AsA/DHA ratio in kiwifruit during storage.Moreover,the OA spraying significantly reduced the contents of acetaldehyde and ethanol in kiwifruit,along with significant decrease in activities of enzymes involved in ethanol fermentation metabolism during the later period of storage,which was beneficial to control off-flavor associated with over accumulation of ethanol during postharvest.It was suggested that pre-harvest spraying of OA might maintain the postharvest quality of kiwifruit in relation to delay in fruit ripening,AsA maintenance and regulation of ethanol fermentation.展开更多
In the microalgae harvesting process,which includes a step for dewatering the algal suspension,directly reusing extracted water in situ would decrease the freshwater footprint of cultivation systems.Among various alga...In the microalgae harvesting process,which includes a step for dewatering the algal suspension,directly reusing extracted water in situ would decrease the freshwater footprint of cultivation systems.Among various algae harvesting techniques,membrane-based filtration has shown numerous advantages.This study evaluated the reuse of permeate streams derived from Scenedesmus obliquus(S.obliquus)biomass filtration under bench-scale and pilot-scale conditions.In particular,this study identified a series of challenges and mechanisms that influence the water reuse potential and the robustness of the membrane harvesting system.In a preliminary phase of this investigation,the health status of the initial biomass was found to have important implications for the harvesting performance and quality of the permeate stream to be reused;healthy biomass ensured better dewatering performance(i.e.,higher water fluxes)and higher quality of the permeate water streams.A series of bench-scale filtration experiments with different combinations of cross-flow velocity and pressure values were performed to identify the operative conditions that would maximize water productivity.The selected conditions,2.4 m·s^(-1)and 1.4 bar(1 bar=105 Pa),respectively,were then applied to drive pilot-scale microfiltration tests to reuse the collected permeate as a new cultivation medium for S.obliquus growth in a pilot-scale photobioreactor.The investigation revealed key differences between the behavior of the membrane systems at the two scales(bench and pilot).It indicated the potential for beneficial reuse of the permeate stream as the pilot-scale experiments ensured high harvesting performance and growth rates of biomass in permeate water that were highly similar to those recorded in the ideal cultivation medium.Finally,different nutrient reintegration protocols were investigated,revealing that both macro-and micro-nutrient levels are critical for the success of the reuse approach.展开更多
Agricultural mechanization plays a pivotal role in the transition from subsistence to commercial agriculture, with a particular focus on labour-intensive activities like harvesting. This study assesses the operational...Agricultural mechanization plays a pivotal role in the transition from subsistence to commercial agriculture, with a particular focus on labour-intensive activities like harvesting. This study assesses the operational characteristics of the BRRI Whole Feed Combine Harvester (Model BRRI WCH2021) at the field level. Developed under the SFMRA project, the harvester’s technical performance and loss assessment were conducted during the Boro 2022 and Aman 2022 seasons in farmer fields in Bangladesh’s Rangpur region. The field efficiency of the harvester was determined to be 62.5% and 57.9% in the Boro and Aman seasons, respectively. Fuel consumption rates were recorded at 2.77 l/ha and 2.31 l/ha for the Boro and Aman seasons. The total harvesting losses, encompassing cutter bar, shatter, cylinder, and separation loss, averaged 0.56% and 0.48% in the Boro and Aman seasons, respectively. Mechanized harvesting with the BRRI Whole Feed Combine Harvester significantly reduced paddy losses by 5.81% compared to manual methods. The field evaluation results indicate the combine harvester’s satisfactory performance, highlighting its potential to alleviate labour demands during peak harvesting. The development of the BRRI WCH offers a sustainable solution for rice harvesting mechanization among progressive farmers. It paves the way for the broader adoption of advanced agricultural technology in Bangladesh.展开更多
Dynamic soaring,which harvests energy from the wind,can enhance Unmanned Aerial Vehicles'(UAVs')range and endurance.However,energy harvesting efficiency issues hinder UAV applications,which can be addressed by...Dynamic soaring,which harvests energy from the wind,can enhance Unmanned Aerial Vehicles'(UAVs')range and endurance.However,energy harvesting efficiency issues hinder UAV applications,which can be addressed by wing morphing.Therefore,this study investigates the influence of albatross wing morphing during dynamic soaring.By constructing a parametric model,the shape of the albatross wing can be modeled and achieve morphing based on joints.From the video data,this paper summarizes the typical wing morphing patterns of the albatross and notices that changes primarily occur during the leeward descent phase.This paper first analyzes the aerodynamic performance of different wing morphing patterns and finds that the drag coefficient can be reduced by 7.75%with a suitable morphing pattern.This paper also explores the drag coefficient reduction mechanism and finds that downwash airflow decreases by 30.32%after wingtip anhedral.Interestingly,the lift-to-drag ratio shows minimal variation under different morphing patterns,within 2%.From the stability perspective,this study finds that the neutral point position changes after morphing.The maximum longitudinal static margin change is 4.9%,enhancing longitudinal stability by increasing the restorative moment arm.The lateral neutral point is 4.87%closer to the center of gravity,decreasing the roll and yaw moments.It can be observed that wingtip anhedral significantly increases the stability of the albatross.Moreover,a flight simulation is carried out to study the morphing influence on trajectory and energy harvesting.The results show that maximum energy gained is improved by 47.99%,and endurance is increased by 13.05%.The results also indicate that the effects of wing morphing are global rather than limited to the phase of morphing occurrence.Finally,based on the results,this paper proposes wing morphing regularity about the wingtip for UAVs.Wingtip bends downward can significantly increase the UAVs'stability and reduce drag,but the overall trajectory needs to be reconsidered after introducing wing morphing.展开更多
Due to technical limitations,existing vibration isolation and energy harvesting(VIEH)devices have poor performance at low frequency.This paper proposes a new multilink-spring mechanism(MLSM)that can be used to solve t...Due to technical limitations,existing vibration isolation and energy harvesting(VIEH)devices have poor performance at low frequency.This paper proposes a new multilink-spring mechanism(MLSM)that can be used to solve this problem.The VIEH performance of the MLSM under harmonic excitation and Gaussian white noise was analyzed.It was found that the MLSM has good vibration isolation performance for low-frequency isolation and the frequency band can be widened by adjusting parameters to achieve a higher energy harvesting power.By comparison with two special cases,the results show that the MLSM is basically the same as the other two oscillators in terms of vibration isolation but has better energy harvesting performance under multistable characteristics.The MLSM is expected to reduce the impact of vibration on high-precision sensitive equipment in some special sites such as subways and mines,and at the same time supply power to structural health monitoring devices.展开更多
Tuned mass damper inerter(TMDI)is a device that couples traditional tuned mass dampers(TMD)with an inertial device.The inertial device produces resistance proportional to the relative acceleration at its two ends thro...Tuned mass damper inerter(TMDI)is a device that couples traditional tuned mass dampers(TMD)with an inertial device.The inertial device produces resistance proportional to the relative acceleration at its two ends through its“inertial”constant.Due to its unique mechanical properties,TMDI has received widespread attention and application in the past twenty years.As different configurations are required in different practical situations,TMDI is still active in the research on vibration control and energy harvesting in structures.This paper provides a comprehensive review of the research status of TMDI.This work first examines the generation and important vibration control characteristics of TMDI.Then,the energy harvesting performance of electromagnetic tuned mass damper inerter(EM-TMDI)is discussed.This work emphasizes the formation of a passive dynamic vibration absorber by coupling traditional TMD with inertial devices.This paper also summarizes the design and implementation of optimal vibration control and energy harvesting for TMDI.Furthermore,this paper details the applications of TMDI in the fields of bridges and building engineering.Finally,this paper summarizes the necessity of research on tuned mass-damper-inertia,the challenges faced currently,and future research directions,such as control of parameters in electromagnetic energy harvesting TMDI systems and low-cost TMDI.展开更多
The supramolecular F?rster resonance energy transfer(FRET)is seen as a promising approach for organic photocatalysis using dyes as catalysts,because it combines the high efficiency of energy transfer with the dynamic ...The supramolecular F?rster resonance energy transfer(FRET)is seen as a promising approach for organic photocatalysis using dyes as catalysts,because it combines the high efficiency of energy transfer with the dynamic responsiveness based on non-covalent interactions.Here we propose a supramolecular FRET photocatalysis strategy forα-oxyamination reaction based on supramolecular confinement effect.The well-designed benzothiadiazole-based cationic monomer as energy donor and the dyes of Nile Red as acceptor are doped into the amphiphilic surfactants of sodium dodecyl sulfate(SDS).Benefitting from the supramolecular confinement space provided by SDS in aqueous environment,the FRET process between the monomer and Nile Red is effectively achieved(exciton migration rate:3.99×10^(14)L mol^(-1)s^(-1)).On this basis,the supramolecular FRET system is used as an efficient energy source to catalyzeα-oxyamination reactions between a series of 1,3-dicarbonyl compounds and 2,2,6,6-tetramethylpiperidine-1-oxyl under white LED light,showing a yield as high as 94%and a turnover frequency value of 3.92 h^(-1).This photocatalytic result shows a great enhancement compared to that of Nile Red alone.展开更多
This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff bodies.An inverted C-shaped bluff body is stationary installed at the upstream position to generate an int...This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff bodies.An inverted C-shaped bluff body is stationary installed at the upstream position to generate an interference wake street,and a cylinder bluff body equipped with a transducer is elastically suspended at the downstream position to harness WIV energy.The hydrodynamics and energy harvesting(EH)performance of the proposed system are investigated via experimental studies.The reduced velocity(U*)ranging from 2 to 14(the corresponding Reynolds number ranging from 15100 to 106200)is considered in the present study.It is found that the wake generated by the inverted C-shaped bluff body significantly affects the EH performance.Enlarging the opening angle(α)of the C-shaped bluff body increases the vibration amplitude of the downstream cylinder,thereby increasing the harvested power.When the spacing(L)between two bluff bodies is two times the cylinder diameter(D),the wake-induced vibration(WIV)mode is observed,while the combined WIV and wake galloping(WG)mode occurs whenαis 150°,and L equals 3D or 4D.The average drag coefficient becomes negative when L is 2D,3D,or 4D.By carefully configuring a C-shaped bluff body,the wake generated by it can bring an augmenting effect on the vibration of the downstream EH cylinder.For example,the RMS power output of the proposed EH system reaches a maximum of 0.31 W at U*=8 and L=4D,which is 300%greater than that of its traditional counterpart.Furthermore,after a number of case stud-ies,it is identified that the proposed EH system can achieve the best performance whenαis 150°and L=2D.展开更多
Locally resonant metamaterials have low-frequency band gaps and the capability of converging vibratory energy in the band gaps at resonant cells.It has been demonstrated by several researchers that the dissipatioin of...Locally resonant metamaterials have low-frequency band gaps and the capability of converging vibratory energy in the band gaps at resonant cells.It has been demonstrated by several researchers that the dissipatioin of vibratory energy within the band gap can be improved by using viscoelastic materials.This paper designs an integrated viscoelastic metamaterial for energy harvesting and vibration isolation.The viscoelastic metamaterial is achieved by a viscoelastic beam periodically arrayed with spatial ball-pendulum nonlinear energy harvesters.The nonlinear resonator with an energy harvesting function is achieved by placing a free-rolling magnetic ball in a spherical cavity with an additional induction coil.The dynamic equations of viscoelastic metamaterials under transverse excitation are established,and the energy harvesting and vibration isolation characteristics within the dispersion relation of viscoelastic metamaterials are analyzed.The results show that the vibrations of the main body of the viscoelastic metamaterial beam are significantly suppressed in the frequency range of the local resonance band gap.At the same time,the elastic waves are limited in the nonlinear resonator with an energy harvesting function,which improves the energy output.Finally,an experimental platform of viscoelastic metamaterial vibration is established for validation purposes.展开更多
This work aims to develop an experimental investigation into the effectiveness of the sliding-mode approach for hybrid vibration-based energy harvesting.A proposed sliding-mode triboelectric-electromagnetic-piezoelect...This work aims to develop an experimental investigation into the effectiveness of the sliding-mode approach for hybrid vibration-based energy harvesting.A proposed sliding-mode triboelectric-electromagnetic-piezoelectric energy harvesting model involves a cantilever beam with a tip mass exposed to magnetic and frictional forces.The experimental findings indicate that the system can achieve its peak inter-well oscillation output within a low-frequency range of 4 Hz–6 Hz.Friction has a lesser impact on the open-circuit voltage output at an excitation acceleration of 1.5g compared with 1g.The distribution of tri-stability changes with the presence of friction.This model provides a deeper understanding of the influence of the dry friction coefficient(0.2–0.5) on the interactive behaviors of different generator units.展开更多
Due to the push for carbon neutrality in various human activities,the development of methods for producing electricity without relying on chemical reaction processes or heat sources has become highly significant.Also,...Due to the push for carbon neutrality in various human activities,the development of methods for producing electricity without relying on chemical reaction processes or heat sources has become highly significant.Also,the challenge lies in achieving microwatt-scale outputs due to the inherent conductivity of the materials and diverting electric currents.To address this challenge,our research has concentrated on utilizing nonconductive mediums for water-based low-cost microfibrous ceramic wools in conjunction with a NaCl aqueous solution for power generation.The main source of electricity originates from the directed movement of water molecules and surface ions through densely packed microfibrous ceramic wools due to the effect of dynamic electric double layer.This occurrence bears resemblance to the natural water transpiration in plants,thereby presenting a fresh and straightforward approach for producing electricity in an ecofriendly manner.The generator module demonstrated in this study,measuring 12×6 cm^(2),exhibited a noteworthy open-circuit voltage of 0.35 V,coupled with a short-circuit current of 0.51 mA.Such low-cost ceramic wools are suitable for ubiquitous,permanent energy sources and hold potential for use as self-powered sensors and systems,eliminating the requirement for external energy sources such as sunlight or heat.展开更多
This paper focuses on the stochastic analysis of a viscoelastic bistable energy harvesting system under colored noise and harmonic excitation, and adopts the time-delayed feedback control to improve its harvesting eff...This paper focuses on the stochastic analysis of a viscoelastic bistable energy harvesting system under colored noise and harmonic excitation, and adopts the time-delayed feedback control to improve its harvesting efficiency. Firstly, to obtain the dimensionless governing equation of the system, the original bistable system is approximated as a system without viscoelastic term by using the stochastic averaging method of energy envelope, and then is further decoupled to derive an equivalent system. The credibility of the proposed method is validated by contrasting the consistency between the numerical and the analytical results of the equivalent system under different noise conditions. The influence of system parameters on average output power is analyzed, and the control effect of the time-delayed feedback control on system performance is compared. The output performance of the system is improved with the occurrence of stochastic resonance(SR). Therefore, the signal-to-noise ratio expression for measuring SR is derived, and the dependence of its SR behavior on different parameters is explored.展开更多
Real-time onboard health monitoring systems are critical for the railway industry to maintain high service quality and operational safety.However,the issue with power supplies for monitoring sensors persists,especiall...Real-time onboard health monitoring systems are critical for the railway industry to maintain high service quality and operational safety.However,the issue with power supplies for monitoring sensors persists,especially for freight trains that lack onboard power.Here,we propose a hybrid piezoelectric-triboelectric rotary generator(HPT-RG)for energy harvesting and vehicle speed sensing.The HPT-RG incorporates a rotational self-adaptive technique that softens the equivalent stiffness,enabling the piezoelectric non-resonant beam to surpass resonance limitations in a low-frequency region.The experiments demonstrate the feasibility of using the HPT-RG as an energy harvesting module to collect the rotational energy of the freight rail transport and power the wireless temperature sensors.To allow multiple monitoring in confined spaces on trains,a triboelectric sensing module is added to the HPT-RG to sense the operation speed and mileage of vehicles.Furthermore,the generator exhibits favorable mechanical durability under more than 600 h of official testing on the train bogie axle.The proposed HPT-RG is essential for creating a truly self-powered,maintenance-free,and zero-carbon onboard wireless monitoring system on freight railways.展开更多
Blue energy,which includes rainfall,tidal current,wave,and water-flow energy,is a promising renewable resource,although its exploitation is limited by current technologies and thus remains low.This form of energy is m...Blue energy,which includes rainfall,tidal current,wave,and water-flow energy,is a promising renewable resource,although its exploitation is limited by current technologies and thus remains low.This form of energy is mainly harvested by electromagnetic generators(EMGs),which generate electricity via Lorenz force-driven electron flows.Triboelectric nano genera tors(TENGs)and TENG networks exhibit superiority over EMGs in low-frequency and high-entropy energy harvesting as a new approach for blue energy harvesting.A TENG produces electrical outputs by adopting the mechanism of Maxwell’s displacement current.To date,a series of research efforts have been made to optimize the structure and performance of TENGs for effective blue energy harvesting and marine environmental applications.Despite the great progress that has been achieved in the use of TENGs in this context so far,continuous exploration is required in energy conversion,device durability,power management,and environmental applications.This review reports on advances in TENGs for blue energy harvesting and marine environmental monitoring.It introduces the theoretical foundations of TENGs and discusses advanced TENG prototypes for blue energy harvesting,including TENG structures that function in freestanding and contact-separation modes.Performance enhancement strategies for TENGs intended for blue energy harvesting are also summarized.Finally,marine environmental applications of TENGs based on blue energy harvesting are discussed.展开更多
Nonlinear energy sink is a passive energy absorption device that surpasses linear dampers, and has gained significant attention in various fields of vibration suppression. This is owing to its capacity to offer high v...Nonlinear energy sink is a passive energy absorption device that surpasses linear dampers, and has gained significant attention in various fields of vibration suppression. This is owing to its capacity to offer high vibration attenuation and robustness across a wide frequency spectrum. Energy harvester is a device employed to convert kinetic energy into usable electric energy. In this paper, we propose an electromagnetic energy harvester enhanced viscoelastic nonlinear energy sink(VNES) to achieve passive vibration suppression and energy harvesting simultaneously. A critical departure from prior studies is the investigation of the stochastic P-bifurcation of the electromechanically coupled VNES system under narrowband random excitation. Initially, approximate analytical solutions are derived using a combination of a multiple-scale method and a perturbation approach. The substantial agreement between theoretical analysis solutions and numerical solutions obtained from Monte Carlo simulation underscores the method's high degree of validity. Furthermore, the effects of system parameters on system responses are carefully examined. Additionally, we demonstrate that stochastic P-bifurcation can be induced by system parameters, which is further verified by the steady-state density functions of displacement. Lastly,we analyze the impacts of various parameters on the mean square current and the mean output power, which are crucial for selecting suitable parameters to enhance the energy harvesting performance.展开更多
Amid the growing interest in triboelectric nanogenerators(TENGs)as novel energy-harvesting devices,several studies have focused on direct current(DC)TENGs to generate a stable DC output for operating electronic device...Amid the growing interest in triboelectric nanogenerators(TENGs)as novel energy-harvesting devices,several studies have focused on direct current(DC)TENGs to generate a stable DC output for operating electronic devices.However,owing to the working mechanisms of conventional DC TENGs,generating a stable DC output from reciprocating motion remains a challenge.Accordingly,we propose a bidirectional rotating DC TENG(BiR-TENG),which can generate DC outputs,regardless of the direction of rotation,from reciprocating motions.The distinct design of the BiR-TENG enables the mechanical rectification of the alternating current output into a rotational-direction-dependent DC output.Furthermore,it allows the conversion of the rotational-direction-dependent DC output into a unidirectional DC output by adapting the configurations depending on the rotational direction.Owing to these tailored design strategies and subsequent optimizations,the BiR-TENG could generate an effective unidirectional DC output.Applications of the BiR-TENG for the reciprocating motions of swinging doors and waves were demonstrated by harnessing this output.This study demonstrates the potential of the BiR-TENG design strategy as an effective and versatile solution for energy harvesting from reciprocating motions,highlighting the suitability of DC outputs as an energy source for electronic devices.展开更多
基金This work was partly supported by the Funda-mental Research Funds for the Central Universi-ties (2232020D-15,2232020A-08,2232020G-01,2232020D-14,and 2232019D3-11)grants (51773037,51973027,51803023,52003044,and 61771123)from the National Natural Science Foundation of China+3 种基金This work has also been supported by the Chang Jiang Scholars Program and the Innovation Program of Shanghai Munici-pal Education Commission (2019-01-07-00-03-E00023)to Prof.Xiaohong Qinthe Shanghai Sailing Program (19YF1400700)the Opening Project of State Key Laboratory of High-Performance Ceramics and Superfine Microstruc-ture (SKL201906SIC)Young Elite Scientists Sponsorship Program by CAST and DHU Distin-guished Young Professor Program to Prof.Liming Wang.
文摘MIL-101(Cr)is a promising moisture absorbent for solar-driven water harvesting from moisture to tackle the worldwide water shortage issue.However,the MIL-101(Cr)powder suffers from a long ab/desorption cycle due to the crystal aggregation caused by its inherent powder properties.Here,we demonstrate a MIL-101(Cr)nanofibrous composite membrane with a nanofibrous matrix where MIL-101(Cr)is monodisperse in the 3D porous nanofibrous matrix through a simple spray-electrospinning strategy.The continuous porous nanofibrous matrix not only offers sufficient sites for MIL-101(Cr)loading but also provides rapid moisture transport channels,resulting in a super-rapid ab/desorption duration of 50 min(including an absorption process for 40 min and a desorption process for 10 min)and multicycle daily water production of 15.9 L kg^(−1) d^(−1).Besides,the MIL-101(Cr)nanofibrous composite membrane establishes a high solar absorption of 92.8%,and excellent photothermal conversion with the surface temperature of 70.7°C under one-sun irradiation.In addition,the MIL-101(Cr)nanofibrous composite membrane shows excellent potential for practical application due to its flexibility,portability,and use stability.This work provides a new perspective of shortening MOF ab/desorption duration by introducing a porous nanofibrous matrix to improve the specific water production for the solar-driven ab/desorption water harvesting technique.
基金supported by the National Nature Science Foundation of China,the National Key Research and Development Program of China(302001109,2016YFD0300508,2017YFD0301602,2018YFD0301105)the Fujian and Taiwan Cultivation Resources Development and Green Cultivation Coordination Innovation Center,China(Fujian 2011 Project,2015-75)the Natural Science Foundation of Fujian Province,China(2022J01142)。
文摘Agronomic measures are the key to promote the sustainable development of ratoon rice by reducing the damage from mechanical crushing to the residual stubble of the main crop, thereby mitigating the impact on axillary bud sprouting and yield formation in ratoon rice. This study used widely recommended conventional rice Jiafuzhan and hybrid rice Yongyou 2640 as the test materials to conduct a four-factor block design field experiment in a greenhouse of the experimental farm of Fujian Agricultural and Forestry University, China from 2018 to 2019.The treatments included fertilization and no fertilization, alternate wetting and drying irrigation and continuous water flooding irrigation, and plots with and without artificial crushing damage on the rice stubble. At the same time, a 13C stable isotope in-situ detection technology was used to fertilize the pot experiment. The results showed significant interactions among varieties, water management, nitrogen application and stubble status.Relative to the long-term water flooding treatment, the treatment with sequential application of nitrogen fertilizer coupled with moderate field drought for root-vigor and tiller promotion before and after harvesting of the main crop, significantly improved the effective tillers from low position nodes. This in turn increased the effective panicles per plant and grains per panicle by reducing the influence of artificial crushing damage on rice stubble and achieving a high yield of the regenerated rice. Furthermore, the partitioning of 13C assimilates to the residual stubble and its axillary buds were significantly improved at the mature stage of the main crop, while the translocation rate to roots and rhizosphere soil was reduced at the later growth stage of ratooning season rice. This was triggered by the metabolism of hormones and polyamines at the stem base regulated by the interaction of water and fertilizer at this time. We therefore suggest that to achieve a high yield of ratoon rice with low stubble height under mechanized harvesting, the timely application of nitrogen fertilizer is fundamental,coupled with moderate field drying for root-vigor preservation and tiller promotion before and after the mechanical harvesting of the main crop.
基金supported by the National Natural Science Foundation of China(Grant No.62001338)the Open Funds for Sanya Science and Education Park(Grant No.2021KF0018)the Fundamental Research Funds for the Central Universities(Grant No.WUT:2021IVB029)
文摘Herein,we report the design,fabrication,and performance of two wireless energy harvesting devices based on highly flexible graphene macroscopic films(FGMFs).We first demonstrate that benefiting from the high conductivity of up to 1×10^(6)S m^(-1)and good resistive stability of FGMFs even under extensive bending,the FGMFs-based rectifying circuit(GRC)exhibits good flexibility and RF-to-DC efficiency of 53%at 2.1 GHz.Moreover,we further expand the application of FGMFs to a flexible wideband monopole rectenna and a 2.45 GHz wearable rectenna for harvesting wireless energy.The wideband rectenna at various bending conditions produces a maximum conversion efficiency of 52%,46%,and 44%at the 5th Generation(5G)2.1 GHz,Industrial Long-Term Evolution(LTE)2.3 GHz,and Scientific Medical(ISM)2.45 GHz,respectively.A 2.45 GHz GRC is optimized and integrated with an AMC-backed wearable antenna.The proposed 2.45 GHz wearable rectenna shows a maximum conversion efficiency of 55.7%.All the results indicate that the highly flexible graphene-film-based rectennas have great potential as a wireless power supplier for smart Internet of Things(loT)applications.
基金supported by National Natural Science Foundation of China(Grant No.61871209,No.62272182 and No.61901210)Shenzhen Science and Technology Program under Grant JCYJ20220530161004009+2 种基金Natural Science Foundation of Hubei Province(Grant No.2022CF011)Wuhan Business University Doctoral Fundamental Research Funds(Grant No.2021KB005)in part by Artificial Intelligence and Intelligent Transportation Joint Technical Center of HUST and Hubei Chutian Intelligent Transportation Co.,LTD under project Intelligent Tunnel Integrated Monitoring and Management System.
文摘Energy limitation of traditional Wireless Sensor Networks(WSNs)greatly confines the network lifetime due to generating and processing massive sensing data with a limited battery.The energy harvesting WSN is a novel network architecture to address the limitation of traditional WSN.However,existing coverage and deployment schemes neglect the environmental correlation of sensor nodes and external energy with respect to physical space.Comprehensively considering the spatial correlation of the environment and the uneven distribution of energy in energy harvesting WSN,we investigate how to deploy a collection of sensor nodes to save the deployment cost while ensuring the target perpetual coverage.The Confident Information Coverage(CIC)model is adopted to formulate the CIC Minimum Deployment Cost Target Perpetual Coverage(CICMTP)problem to minimize the deployed sensor nodes.As the CICMTP is NP-hard,we devise two approximation algorithms named Local Greedy Threshold Algorithm based on CIC(LGTA-CIC)and Overall Greedy Search Algorithm based on CIC(OGSA-CIC).The LGTA-CIC has a low time complexity and the OGSA-CIC has a better approximation rate.Extensive simulation results demonstrate that the OGSA-CIC is able to achieve lower deployment cost and the performance of the proposed algorithms outperforms GRNP,TPNP and EENP algorithms.
基金the financial support provided by the National Natural Science Foundation of China (31671908)the National Key Research and Development Program of China (2016YFD0400901)
文摘The kiwifruit trees(Actinidia deliciosa cv.Bruno)were sprayed with 5 mmol L-1 oxalic acid(OA)or water(as control)at 130,137 or 144 d after full-blossom,and then the fruit were harvested at commercial maturity and stored at room temperature(20±1)℃ for 13 d.The effect of pre-harvest spraying of OA on postharvest quality of kiwifruit was evaluated during storage.The OA spraying slowed the increase in soluble solids content(SSC)and decrease in titratable acid(TA),as well as increased contents of ascorbic acid(AsA)and total-AsA accompanied with higher AsA/DHA ratio in kiwifruit during storage.Moreover,the OA spraying significantly reduced the contents of acetaldehyde and ethanol in kiwifruit,along with significant decrease in activities of enzymes involved in ethanol fermentation metabolism during the later period of storage,which was beneficial to control off-flavor associated with over accumulation of ethanol during postharvest.It was suggested that pre-harvest spraying of OA might maintain the postharvest quality of kiwifruit in relation to delay in fruit ripening,AsA maintenance and regulation of ethanol fermentation.
基金supported by the Politecnico di Torino and the CleanWaterCenter@PoliTo(58_DIM20TIRALB,58_DIM22TIRALB,and 01_TRIN_CI_CWC).
文摘In the microalgae harvesting process,which includes a step for dewatering the algal suspension,directly reusing extracted water in situ would decrease the freshwater footprint of cultivation systems.Among various algae harvesting techniques,membrane-based filtration has shown numerous advantages.This study evaluated the reuse of permeate streams derived from Scenedesmus obliquus(S.obliquus)biomass filtration under bench-scale and pilot-scale conditions.In particular,this study identified a series of challenges and mechanisms that influence the water reuse potential and the robustness of the membrane harvesting system.In a preliminary phase of this investigation,the health status of the initial biomass was found to have important implications for the harvesting performance and quality of the permeate stream to be reused;healthy biomass ensured better dewatering performance(i.e.,higher water fluxes)and higher quality of the permeate water streams.A series of bench-scale filtration experiments with different combinations of cross-flow velocity and pressure values were performed to identify the operative conditions that would maximize water productivity.The selected conditions,2.4 m·s^(-1)and 1.4 bar(1 bar=105 Pa),respectively,were then applied to drive pilot-scale microfiltration tests to reuse the collected permeate as a new cultivation medium for S.obliquus growth in a pilot-scale photobioreactor.The investigation revealed key differences between the behavior of the membrane systems at the two scales(bench and pilot).It indicated the potential for beneficial reuse of the permeate stream as the pilot-scale experiments ensured high harvesting performance and growth rates of biomass in permeate water that were highly similar to those recorded in the ideal cultivation medium.Finally,different nutrient reintegration protocols were investigated,revealing that both macro-and micro-nutrient levels are critical for the success of the reuse approach.
文摘Agricultural mechanization plays a pivotal role in the transition from subsistence to commercial agriculture, with a particular focus on labour-intensive activities like harvesting. This study assesses the operational characteristics of the BRRI Whole Feed Combine Harvester (Model BRRI WCH2021) at the field level. Developed under the SFMRA project, the harvester’s technical performance and loss assessment were conducted during the Boro 2022 and Aman 2022 seasons in farmer fields in Bangladesh’s Rangpur region. The field efficiency of the harvester was determined to be 62.5% and 57.9% in the Boro and Aman seasons, respectively. Fuel consumption rates were recorded at 2.77 l/ha and 2.31 l/ha for the Boro and Aman seasons. The total harvesting losses, encompassing cutter bar, shatter, cylinder, and separation loss, averaged 0.56% and 0.48% in the Boro and Aman seasons, respectively. Mechanized harvesting with the BRRI Whole Feed Combine Harvester significantly reduced paddy losses by 5.81% compared to manual methods. The field evaluation results indicate the combine harvester’s satisfactory performance, highlighting its potential to alleviate labour demands during peak harvesting. The development of the BRRI WCH offers a sustainable solution for rice harvesting mechanization among progressive farmers. It paves the way for the broader adoption of advanced agricultural technology in Bangladesh.
基金sponsored by Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.CX2024037)。
文摘Dynamic soaring,which harvests energy from the wind,can enhance Unmanned Aerial Vehicles'(UAVs')range and endurance.However,energy harvesting efficiency issues hinder UAV applications,which can be addressed by wing morphing.Therefore,this study investigates the influence of albatross wing morphing during dynamic soaring.By constructing a parametric model,the shape of the albatross wing can be modeled and achieve morphing based on joints.From the video data,this paper summarizes the typical wing morphing patterns of the albatross and notices that changes primarily occur during the leeward descent phase.This paper first analyzes the aerodynamic performance of different wing morphing patterns and finds that the drag coefficient can be reduced by 7.75%with a suitable morphing pattern.This paper also explores the drag coefficient reduction mechanism and finds that downwash airflow decreases by 30.32%after wingtip anhedral.Interestingly,the lift-to-drag ratio shows minimal variation under different morphing patterns,within 2%.From the stability perspective,this study finds that the neutral point position changes after morphing.The maximum longitudinal static margin change is 4.9%,enhancing longitudinal stability by increasing the restorative moment arm.The lateral neutral point is 4.87%closer to the center of gravity,decreasing the roll and yaw moments.It can be observed that wingtip anhedral significantly increases the stability of the albatross.Moreover,a flight simulation is carried out to study the morphing influence on trajectory and energy harvesting.The results show that maximum energy gained is improved by 47.99%,and endurance is increased by 13.05%.The results also indicate that the effects of wing morphing are global rather than limited to the phase of morphing occurrence.Finally,based on the results,this paper proposes wing morphing regularity about the wingtip for UAVs.Wingtip bends downward can significantly increase the UAVs'stability and reduce drag,but the overall trajectory needs to be reconsidered after introducing wing morphing.
基金Project supported by Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2022A1515010967 and 2023A1515012821)the National Natural Science Foundation of China(Grant Nos.12002272 and 12272293)Opening Project of Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province(Grant No.SZDKF-202101)。
文摘Due to technical limitations,existing vibration isolation and energy harvesting(VIEH)devices have poor performance at low frequency.This paper proposes a new multilink-spring mechanism(MLSM)that can be used to solve this problem.The VIEH performance of the MLSM under harmonic excitation and Gaussian white noise was analyzed.It was found that the MLSM has good vibration isolation performance for low-frequency isolation and the frequency band can be widened by adjusting parameters to achieve a higher energy harvesting power.By comparison with two special cases,the results show that the MLSM is basically the same as the other two oscillators in terms of vibration isolation but has better energy harvesting performance under multistable characteristics.The MLSM is expected to reduce the impact of vibration on high-precision sensitive equipment in some special sites such as subways and mines,and at the same time supply power to structural health monitoring devices.
基金funded by the Anhui Provincial Natural Science Foundation(Grant No.2008085QE245)the Natural Science Research Project of Higher Education Institutions in Anhui Province(Grant No.2022AH040045)+1 种基金the Project of Science and Technology Plan of Department of Housing and Urban-Rural Development of Anhui Province(Grant No.2021-YF22)the National College Student Innovation and Entrepreneurship Training Program Project(Grant No.202210878005).
文摘Tuned mass damper inerter(TMDI)is a device that couples traditional tuned mass dampers(TMD)with an inertial device.The inertial device produces resistance proportional to the relative acceleration at its two ends through its“inertial”constant.Due to its unique mechanical properties,TMDI has received widespread attention and application in the past twenty years.As different configurations are required in different practical situations,TMDI is still active in the research on vibration control and energy harvesting in structures.This paper provides a comprehensive review of the research status of TMDI.This work first examines the generation and important vibration control characteristics of TMDI.Then,the energy harvesting performance of electromagnetic tuned mass damper inerter(EM-TMDI)is discussed.This work emphasizes the formation of a passive dynamic vibration absorber by coupling traditional TMD with inertial devices.This paper also summarizes the design and implementation of optimal vibration control and energy harvesting for TMDI.Furthermore,this paper details the applications of TMDI in the fields of bridges and building engineering.Finally,this paper summarizes the necessity of research on tuned mass-damper-inertia,the challenges faced currently,and future research directions,such as control of parameters in electromagnetic energy harvesting TMDI systems and low-cost TMDI.
基金financially supported by the National Natural Science Foundation of China (Nos.22371230,22022107,22001213,and 22071197)the Postdoctoral Science Foundation of China (Nos.2023M732855,2022TQ0258)the Shaanxi Fundamental Science Research Project for Chemistry & Biology (No.22JHQ020)。
文摘The supramolecular F?rster resonance energy transfer(FRET)is seen as a promising approach for organic photocatalysis using dyes as catalysts,because it combines the high efficiency of energy transfer with the dynamic responsiveness based on non-covalent interactions.Here we propose a supramolecular FRET photocatalysis strategy forα-oxyamination reaction based on supramolecular confinement effect.The well-designed benzothiadiazole-based cationic monomer as energy donor and the dyes of Nile Red as acceptor are doped into the amphiphilic surfactants of sodium dodecyl sulfate(SDS).Benefitting from the supramolecular confinement space provided by SDS in aqueous environment,the FRET process between the monomer and Nile Red is effectively achieved(exciton migration rate:3.99×10^(14)L mol^(-1)s^(-1)).On this basis,the supramolecular FRET system is used as an efficient energy source to catalyzeα-oxyamination reactions between a series of 1,3-dicarbonyl compounds and 2,2,6,6-tetramethylpiperidine-1-oxyl under white LED light,showing a yield as high as 94%and a turnover frequency value of 3.92 h^(-1).This photocatalytic result shows a great enhancement compared to that of Nile Red alone.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51977196,52277227,and52305135)Open Project of Henan Key Laboratory of Intelligent Manufacturing of Mechanical Equipment,Zhengzhou University of Light Industry(Grant No.IM202302)+3 种基金the Natural Science Foundation of Excellent Youth of Henan Province(Grant No.222300420076)the Science and Technology Research&Development Joint Foundation of Henan Province-Young Scientists(Grant No.225200810099)the Program for Science&Technology Innovation Talents in Universities of Henan Province(Grant No.23HASTIT010)the National Center for International Research of Subsea Engineering Technology and Equipment(Grant No.3132023366).
文摘This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff bodies.An inverted C-shaped bluff body is stationary installed at the upstream position to generate an interference wake street,and a cylinder bluff body equipped with a transducer is elastically suspended at the downstream position to harness WIV energy.The hydrodynamics and energy harvesting(EH)performance of the proposed system are investigated via experimental studies.The reduced velocity(U*)ranging from 2 to 14(the corresponding Reynolds number ranging from 15100 to 106200)is considered in the present study.It is found that the wake generated by the inverted C-shaped bluff body significantly affects the EH performance.Enlarging the opening angle(α)of the C-shaped bluff body increases the vibration amplitude of the downstream cylinder,thereby increasing the harvested power.When the spacing(L)between two bluff bodies is two times the cylinder diameter(D),the wake-induced vibration(WIV)mode is observed,while the combined WIV and wake galloping(WG)mode occurs whenαis 150°,and L equals 3D or 4D.The average drag coefficient becomes negative when L is 2D,3D,or 4D.By carefully configuring a C-shaped bluff body,the wake generated by it can bring an augmenting effect on the vibration of the downstream EH cylinder.For example,the RMS power output of the proposed EH system reaches a maximum of 0.31 W at U*=8 and L=4D,which is 300%greater than that of its traditional counterpart.Furthermore,after a number of case stud-ies,it is identified that the proposed EH system can achieve the best performance whenαis 150°and L=2D.
基金supported by the National Natural Science Foundation of China(Nos.12272210,11872037,11872159)the Innovation Program of Shanghai Municipal Education Commission of China(No.2017-01-07-00-09-E00019)。
文摘Locally resonant metamaterials have low-frequency band gaps and the capability of converging vibratory energy in the band gaps at resonant cells.It has been demonstrated by several researchers that the dissipatioin of vibratory energy within the band gap can be improved by using viscoelastic materials.This paper designs an integrated viscoelastic metamaterial for energy harvesting and vibration isolation.The viscoelastic metamaterial is achieved by a viscoelastic beam periodically arrayed with spatial ball-pendulum nonlinear energy harvesters.The nonlinear resonator with an energy harvesting function is achieved by placing a free-rolling magnetic ball in a spherical cavity with an additional induction coil.The dynamic equations of viscoelastic metamaterials under transverse excitation are established,and the energy harvesting and vibration isolation characteristics within the dispersion relation of viscoelastic metamaterials are analyzed.The results show that the vibrations of the main body of the viscoelastic metamaterial beam are significantly suppressed in the frequency range of the local resonance band gap.At the same time,the elastic waves are limited in the nonlinear resonator with an energy harvesting function,which improves the energy output.Finally,an experimental platform of viscoelastic metamaterial vibration is established for validation purposes.
基金Project supported by the National Natural Science Foundation of China (Nos. 12372024 and 12002300)the Natural Science Foundation of Hebei Province of China (No. A2021203013)。
文摘This work aims to develop an experimental investigation into the effectiveness of the sliding-mode approach for hybrid vibration-based energy harvesting.A proposed sliding-mode triboelectric-electromagnetic-piezoelectric energy harvesting model involves a cantilever beam with a tip mass exposed to magnetic and frictional forces.The experimental findings indicate that the system can achieve its peak inter-well oscillation output within a low-frequency range of 4 Hz–6 Hz.Friction has a lesser impact on the open-circuit voltage output at an excitation acceleration of 1.5g compared with 1g.The distribution of tri-stability changes with the presence of friction.This model provides a deeper understanding of the influence of the dry friction coefficient(0.2–0.5) on the interactive behaviors of different generator units.
基金supported by JSPS Kakenhi program(program number 16H06364)and JST CRESTThe authors extend their appreciation to the Deputyship for Research and Innovation,“Ministry of Education”in Saudi Arabia for funding this research(IFKSUOR3-615-5)O.M.also thank the support of Tomsk State University Development Programme(priority-2030)for this work.
文摘Due to the push for carbon neutrality in various human activities,the development of methods for producing electricity without relying on chemical reaction processes or heat sources has become highly significant.Also,the challenge lies in achieving microwatt-scale outputs due to the inherent conductivity of the materials and diverting electric currents.To address this challenge,our research has concentrated on utilizing nonconductive mediums for water-based low-cost microfibrous ceramic wools in conjunction with a NaCl aqueous solution for power generation.The main source of electricity originates from the directed movement of water molecules and surface ions through densely packed microfibrous ceramic wools due to the effect of dynamic electric double layer.This occurrence bears resemblance to the natural water transpiration in plants,thereby presenting a fresh and straightforward approach for producing electricity in an ecofriendly manner.The generator module demonstrated in this study,measuring 12×6 cm^(2),exhibited a noteworthy open-circuit voltage of 0.35 V,coupled with a short-circuit current of 0.51 mA.Such low-cost ceramic wools are suitable for ubiquitous,permanent energy sources and hold potential for use as self-powered sensors and systems,eliminating the requirement for external energy sources such as sunlight or heat.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11902081)the Science and Technology Projects of Guangzhou (Grant No. 202201010326)the Guangdong Provincial Basic and Applied Basic Research Foundation (Grant No. 2023A1515010833)。
文摘This paper focuses on the stochastic analysis of a viscoelastic bistable energy harvesting system under colored noise and harmonic excitation, and adopts the time-delayed feedback control to improve its harvesting efficiency. Firstly, to obtain the dimensionless governing equation of the system, the original bistable system is approximated as a system without viscoelastic term by using the stochastic averaging method of energy envelope, and then is further decoupled to derive an equivalent system. The credibility of the proposed method is validated by contrasting the consistency between the numerical and the analytical results of the equivalent system under different noise conditions. The influence of system parameters on average output power is analyzed, and the control effect of the time-delayed feedback control on system performance is compared. The output performance of the system is improved with the occurrence of stochastic resonance(SR). Therefore, the signal-to-noise ratio expression for measuring SR is derived, and the dependence of its SR behavior on different parameters is explored.
基金supported by the National Natural Science Foundation of China(Grant Nos.12302022,12172248,12021002,and 12132010)Tianjin Research Program of Application Foundation and Advanced Technology(Grant No.22JCQNJC00780)+1 种基金the State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures(Grant No.KF2024-09)the IoT Standards and Application Key Laboratory of the Ministry of Industry and Information Technology(Grant No.202306).
文摘Real-time onboard health monitoring systems are critical for the railway industry to maintain high service quality and operational safety.However,the issue with power supplies for monitoring sensors persists,especially for freight trains that lack onboard power.Here,we propose a hybrid piezoelectric-triboelectric rotary generator(HPT-RG)for energy harvesting and vehicle speed sensing.The HPT-RG incorporates a rotational self-adaptive technique that softens the equivalent stiffness,enabling the piezoelectric non-resonant beam to surpass resonance limitations in a low-frequency region.The experiments demonstrate the feasibility of using the HPT-RG as an energy harvesting module to collect the rotational energy of the freight rail transport and power the wireless temperature sensors.To allow multiple monitoring in confined spaces on trains,a triboelectric sensing module is added to the HPT-RG to sense the operation speed and mileage of vehicles.Furthermore,the generator exhibits favorable mechanical durability under more than 600 h of official testing on the train bogie axle.The proposed HPT-RG is essential for creating a truly self-powered,maintenance-free,and zero-carbon onboard wireless monitoring system on freight railways.
基金the National Key Research and Development Project from the Minister of Science and Technology(2021YFA1201601 and 2021YFA1201604)the Innovation Project of Ocean Science and Technology(22-3-3-hygg-18-hy)+2 种基金the project supported by the Fundamental Research Funds for the Central Universities(E2E46805)the China National Postdoctoral Program for Innovative Talents(BX20220292)the China Postdoctoral Science Foundation(2022M723100)。
文摘Blue energy,which includes rainfall,tidal current,wave,and water-flow energy,is a promising renewable resource,although its exploitation is limited by current technologies and thus remains low.This form of energy is mainly harvested by electromagnetic generators(EMGs),which generate electricity via Lorenz force-driven electron flows.Triboelectric nano genera tors(TENGs)and TENG networks exhibit superiority over EMGs in low-frequency and high-entropy energy harvesting as a new approach for blue energy harvesting.A TENG produces electrical outputs by adopting the mechanism of Maxwell’s displacement current.To date,a series of research efforts have been made to optimize the structure and performance of TENGs for effective blue energy harvesting and marine environmental applications.Despite the great progress that has been achieved in the use of TENGs in this context so far,continuous exploration is required in energy conversion,device durability,power management,and environmental applications.This review reports on advances in TENGs for blue energy harvesting and marine environmental monitoring.It introduces the theoretical foundations of TENGs and discusses advanced TENG prototypes for blue energy harvesting,including TENG structures that function in freestanding and contact-separation modes.Performance enhancement strategies for TENGs intended for blue energy harvesting are also summarized.Finally,marine environmental applications of TENGs based on blue energy harvesting are discussed.
基金Project supported by the National Natural Science Foundation of China(Grant No.12002089)the Science and Technology Projects in Guangzhou(Grant No.2023A04J1323)UKRI Horizon Europe Guarantee(Grant No.EP/Y016130/1)。
文摘Nonlinear energy sink is a passive energy absorption device that surpasses linear dampers, and has gained significant attention in various fields of vibration suppression. This is owing to its capacity to offer high vibration attenuation and robustness across a wide frequency spectrum. Energy harvester is a device employed to convert kinetic energy into usable electric energy. In this paper, we propose an electromagnetic energy harvester enhanced viscoelastic nonlinear energy sink(VNES) to achieve passive vibration suppression and energy harvesting simultaneously. A critical departure from prior studies is the investigation of the stochastic P-bifurcation of the electromechanically coupled VNES system under narrowband random excitation. Initially, approximate analytical solutions are derived using a combination of a multiple-scale method and a perturbation approach. The substantial agreement between theoretical analysis solutions and numerical solutions obtained from Monte Carlo simulation underscores the method's high degree of validity. Furthermore, the effects of system parameters on system responses are carefully examined. Additionally, we demonstrate that stochastic P-bifurcation can be induced by system parameters, which is further verified by the steady-state density functions of displacement. Lastly,we analyze the impacts of various parameters on the mean square current and the mean output power, which are crucial for selecting suitable parameters to enhance the energy harvesting performance.
基金This work was supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.2022R1C1C1008831).This work was also supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Ministry of Trade,Industry and Energy of Korea(No.RS-2023-00244330).S J P was supported by Basic Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2018R1A6A1A03025526).
文摘Amid the growing interest in triboelectric nanogenerators(TENGs)as novel energy-harvesting devices,several studies have focused on direct current(DC)TENGs to generate a stable DC output for operating electronic devices.However,owing to the working mechanisms of conventional DC TENGs,generating a stable DC output from reciprocating motion remains a challenge.Accordingly,we propose a bidirectional rotating DC TENG(BiR-TENG),which can generate DC outputs,regardless of the direction of rotation,from reciprocating motions.The distinct design of the BiR-TENG enables the mechanical rectification of the alternating current output into a rotational-direction-dependent DC output.Furthermore,it allows the conversion of the rotational-direction-dependent DC output into a unidirectional DC output by adapting the configurations depending on the rotational direction.Owing to these tailored design strategies and subsequent optimizations,the BiR-TENG could generate an effective unidirectional DC output.Applications of the BiR-TENG for the reciprocating motions of swinging doors and waves were demonstrated by harnessing this output.This study demonstrates the potential of the BiR-TENG design strategy as an effective and versatile solution for energy harvesting from reciprocating motions,highlighting the suitability of DC outputs as an energy source for electronic devices.