With a transition towards clean and low-carbon renewable energy,against the backdrop of the fossil-energy crisis and rising pollution,ocean energy has been proposed as a significant possibility for mitigating climate ...With a transition towards clean and low-carbon renewable energy,against the backdrop of the fossil-energy crisis and rising pollution,ocean energy has been proposed as a significant possibility for mitigating climate change and energy shortages for its characteristics of clean,renewable,and abundant.The rapid development of energy harvesting technology has led to extensive applications of ocean wave energy,which,however,has faced certain challenges due to the low-frequency and unstable nature of ocean waves.This paper overviews the debut and development of ocean wave energy harvesting technology,and discusses the potential and application paradigm for energy harvesting in the“intelligent ocean.”We first describe for readers the mechanisms and applications of traditional wave energy converters,and then discuss current challenges in energy harvesting performance connected to the characteristics of ocean waves.Next,we summarize the progress in wave energy harvesting with a focus on advanced technologies(e.g.,data-driven design and optimization)and multifunctional energy materials(e.g.,triboelectric metamaterials),and finally propose recommendations for future development.展开更多
Lower temperature waste heats less than 373 K have strong potentials to supply additional energies because of their enormous quantities and ubiquity. Accordingly, reinforcement of power generations harvesting low temp...Lower temperature waste heats less than 373 K have strong potentials to supply additional energies because of their enormous quantities and ubiquity. Accordingly, reinforcement of power generations harvesting low temperature heats is one of the urgent tasks for the current generation in order to accomplish energy sustainability in the coming decades. In this study, a liquid turbine power generator driven by lower temperature heats below 373 K was proposed in the aim of expanding selectable options for harvesting low temperature waste heats less than 373 K. The proposing system was so simply that it was mainly composed of a liquid turbine, a liquid container with a biphasic medium of water and an underlying water-insoluble low-boiling-point medium in a liquid phase, a heating section for vaporization of the liquid and a cooling section for entropy discharge outside the system. Assumed power generating steps via the proposing liquid turbine power generator were as follows: step 1: the underlying low-boiling-point medium in a liquid phase was vaporized, step 2: the surfacing vapor bubbles of low-boiling-point medium accompanied the biphasic medium in their wakes, step 3: such high momentum flux by step 2 rotated the liquid turbine (i.e. power generation), step 4: the surfacing low-boiling-point medium vapor was gradually condensed into droplets, step 5: the low-boiling-point medium droplets were submerged to the underlying medium in a liquid phase. Experiments with a prototype liquid turbine power generator proved power generations in accordance with the assumed steps at a little higher than ordinary temperature. Increasing output voltage could be obtained with an increase in the cooling temperature among tested ranging from 294 to 296 K in contrast to normal thermal engines. Further improvements of the direct current voltage from the proposing liquid turbine power generator can be expected by means of far more vigorous multiphase flow induced by adding solid powders and theoretical optimizations of heat and mass transfers.展开更多
Energy harvesting(EH)technology in wireless communication is a promising approach to extend the lifetime of future wireless networks.A cross-layer optimal adaptation policy for a point-to-point energy harvesting(EH)wi...Energy harvesting(EH)technology in wireless communication is a promising approach to extend the lifetime of future wireless networks.A cross-layer optimal adaptation policy for a point-to-point energy harvesting(EH)wireless communication system with finite buffer constraints over a Rayleigh fading channel based on a Semi-Markov Decision Process(SMDP)is investigated.Most adaptation strategies in the literature are based on channeldependent adaptation.However,besides considering the channel,the state of the energy capacitor and the data buffer are also involved when proposing a dynamic modulation policy for EH wireless networks.Unlike the channeldependent policy,which is a physical layer-based optimization,the proposed cross-layer dynamic modulation policy is a guarantee to meet the overflow requirements of the upper layer by maximizing the throughput while optimizing the transmission power and minimizing the dropping packets.Based on the states of the channel conditions,data buffer,and energy capacitor,the scheduler selects a particular action corresponding to the selected modulation constellation.Moreover,the packets are modulated into symbols according to the selected modulation type to be ready for transmission over the Rayleigh fading channel.Simulations are used to test the performance of the proposed cross-layer policy scheme,which shows that it significantly outperforms the physical layer channel-dependent policy scheme in terms of throughput only.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52022092,51979247,and 52211530092)the Talent Program of Zhejiang Province(No.2021R52050)+2 种基金the Key Research and Development Plan of Zhejiang Province,China(Nos.2021C03181 and 2023C03122)the Key-Area Research and Development Program of Guangdong Province(No.2021B0707030002),Chinathe Startup Fund of the Hundred Talent Program at Zhejiang University,China。
文摘With a transition towards clean and low-carbon renewable energy,against the backdrop of the fossil-energy crisis and rising pollution,ocean energy has been proposed as a significant possibility for mitigating climate change and energy shortages for its characteristics of clean,renewable,and abundant.The rapid development of energy harvesting technology has led to extensive applications of ocean wave energy,which,however,has faced certain challenges due to the low-frequency and unstable nature of ocean waves.This paper overviews the debut and development of ocean wave energy harvesting technology,and discusses the potential and application paradigm for energy harvesting in the“intelligent ocean.”We first describe for readers the mechanisms and applications of traditional wave energy converters,and then discuss current challenges in energy harvesting performance connected to the characteristics of ocean waves.Next,we summarize the progress in wave energy harvesting with a focus on advanced technologies(e.g.,data-driven design and optimization)and multifunctional energy materials(e.g.,triboelectric metamaterials),and finally propose recommendations for future development.
文摘Lower temperature waste heats less than 373 K have strong potentials to supply additional energies because of their enormous quantities and ubiquity. Accordingly, reinforcement of power generations harvesting low temperature heats is one of the urgent tasks for the current generation in order to accomplish energy sustainability in the coming decades. In this study, a liquid turbine power generator driven by lower temperature heats below 373 K was proposed in the aim of expanding selectable options for harvesting low temperature waste heats less than 373 K. The proposing system was so simply that it was mainly composed of a liquid turbine, a liquid container with a biphasic medium of water and an underlying water-insoluble low-boiling-point medium in a liquid phase, a heating section for vaporization of the liquid and a cooling section for entropy discharge outside the system. Assumed power generating steps via the proposing liquid turbine power generator were as follows: step 1: the underlying low-boiling-point medium in a liquid phase was vaporized, step 2: the surfacing vapor bubbles of low-boiling-point medium accompanied the biphasic medium in their wakes, step 3: such high momentum flux by step 2 rotated the liquid turbine (i.e. power generation), step 4: the surfacing low-boiling-point medium vapor was gradually condensed into droplets, step 5: the low-boiling-point medium droplets were submerged to the underlying medium in a liquid phase. Experiments with a prototype liquid turbine power generator proved power generations in accordance with the assumed steps at a little higher than ordinary temperature. Increasing output voltage could be obtained with an increase in the cooling temperature among tested ranging from 294 to 296 K in contrast to normal thermal engines. Further improvements of the direct current voltage from the proposing liquid turbine power generator can be expected by means of far more vigorous multiphase flow induced by adding solid powders and theoretical optimizations of heat and mass transfers.
基金The authors would like to thank the Deanship of Scientific Research at Majmaah University for supporting this work under Project Number No-R-2021-60.
文摘Energy harvesting(EH)technology in wireless communication is a promising approach to extend the lifetime of future wireless networks.A cross-layer optimal adaptation policy for a point-to-point energy harvesting(EH)wireless communication system with finite buffer constraints over a Rayleigh fading channel based on a Semi-Markov Decision Process(SMDP)is investigated.Most adaptation strategies in the literature are based on channeldependent adaptation.However,besides considering the channel,the state of the energy capacitor and the data buffer are also involved when proposing a dynamic modulation policy for EH wireless networks.Unlike the channeldependent policy,which is a physical layer-based optimization,the proposed cross-layer dynamic modulation policy is a guarantee to meet the overflow requirements of the upper layer by maximizing the throughput while optimizing the transmission power and minimizing the dropping packets.Based on the states of the channel conditions,data buffer,and energy capacitor,the scheduler selects a particular action corresponding to the selected modulation constellation.Moreover,the packets are modulated into symbols according to the selected modulation type to be ready for transmission over the Rayleigh fading channel.Simulations are used to test the performance of the proposed cross-layer policy scheme,which shows that it significantly outperforms the physical layer channel-dependent policy scheme in terms of throughput only.
