The identification and understanding of cryptic intraspecific evolutionary units(lineages) are crucial for planning effective conservation strategies aimed at preserving genetic diversity in endangered species.However...The identification and understanding of cryptic intraspecific evolutionary units(lineages) are crucial for planning effective conservation strategies aimed at preserving genetic diversity in endangered species.However, the factors driving the evolution and maintenance of these intraspecific lineages in most endangered species remain poorly understood. In this study, we conducted resequencing of 77 individuals from 22 natural populations of Davidia involucrata, a “living fossil” dove tree endemic to central and southwest China. Our analysis revealed the presence of three distinct local lineages within this endangered species, which emerged approximately 3.09 and 0.32 million years ago. These divergence events align well with the geographic and climatic oscillations that occurred across the distributional range.Additionally, we observed frequent hybridization events between the three lineages, resulting in the formation of hybrid populations in their adjacent as well as disjunct regions. These hybridizations likely arose from climate-driven population expansion and/or long-distance gene flow. Furthermore, we identified numerous environment-correlated gene variants across the total and many other genes that exhibited signals of positive evolution during the maintenance of two major local lineages. Our findings shed light on the highly dynamic evolution underlying the remarkably similar phenotype of this endangered species. Importantly, these results not only provide guidance for the development of conservation plans but also enhance our understanding of evolutionary past for this and other endangered species with similar histories.展开更多
As maternal parents, diploid （L202-2x） and autotetraploid （L202-4x） of Oryza sativa cv. L2O2 were crossed with O. officinalis. Embryo development and fertilization in these two crosses were comparatively studied. ...As maternal parents, diploid （L202-2x） and autotetraploid （L202-4x） of Oryza sativa cv. L2O2 were crossed with O. officinalis. Embryo development and fertilization in these two crosses were comparatively studied. There were no mature hybrid seeds obtained because all the hybridized spikelets died 30 days after pollination. The main reasons for no seed set were abnormal fertilization and development of the embryos and endosperms in the interspecific hybrids. There were doublefertilization, egg cell single-fertilization and non-fertilization in these crosses. Although 59.45% and 54.87% of hybrid embryos produced in the crosses of L202-2x/O. officinalis and L202-4x/O. officinalis, respectively, hybrid embryos ceased to develop or degenerated and plenty of free endosperm nuclei were in disaggregating state without developing cellular endosperms three days after pollination. Besides, some embryological differences in these two crosses were found, that is, the rate of double-fertilization and total rate of doubleand single-fertilization in L202-2x/O. officinalis were higher than those in L202-4x/O. officinalis. The embryo and endosperm of hybrids developed more slowly, and embryos and free endosperm nuclei were more severely degenerated in L202-4x/O. officinalis than in L202-2x/O. officinalis. Five days after pollination, a few of embryos in L202-2x/O. officinalis developed into pear-shaped ones, however, embryos in L202-4x/O. officinalis were all degenerated. Therefore, it is more difficult to obtain interspecific hybrids by wide crosses between autotetraploid of O. sativa and O. officinalis.展开更多
Single-atom catalysts(SACs)are rapidly standing at the forefront of catalytic development due to their unique structures with significantly different catalytic activity,selectivity,and stability from conventional nano...Single-atom catalysts(SACs)are rapidly standing at the forefront of catalytic development due to their unique structures with significantly different catalytic activity,selectivity,and stability from conventional nanocatalysts.The electronic properties and catalytic performances of SACs hinge on the results of orbital hybridization of isolated central atoms with ligand atoms as well as of central atoms with bonding atoms provided by intermediates.Therefore,we conduct multifaceted explorations around orbital hybridizations in single-atom catalysis to elucidate the structure-activity relationships.Firstly,we introduce the basic theoretical knowledge related to orbital hybridizations,and summarize the main descriptors of orbital hybridizations,focusing on the discussion of the types of orbital hybridizations in singleatom catalysis.Then,we briefly sum up the application of orbital hybridizations in single-atom electrocatalysis and put forward important strategies for regulating orbital hybridizations in SACs to improve the catalytic performances.Finally,we present a personal perspective on the future challenges and opportunities of orbital hybridizations in single-atom catalysis.展开更多
为探究混合Ⅲ(HybridⅢ)假人与人体乘员约束测试装置(test device for human occupant restraint,THOR)在小偏置碰撞试验中的生物逼真度差异,对比分析了HybridⅢ假人、THOR和人体安全模型(total human model for safety,THUMS)3种乘员...为探究混合Ⅲ(HybridⅢ)假人与人体乘员约束测试装置(test device for human occupant restraint,THOR)在小偏置碰撞试验中的生物逼真度差异,对比分析了HybridⅢ假人、THOR和人体安全模型(total human model for safety,THUMS)3种乘员模型在不同小偏置碰撞模式下的碰撞响应情况.采用有限元数值模拟方法,以吸能与侧滑两种典型小偏置碰撞模式的整车模型在碰撞过程中的脉冲曲线作为边界条件;结合包含完整内饰结构的某中型轿车驾驶舱模型和HybridⅢ假人、THOR以及THUMS,构建驾驶员侧约束系统仿真模型,分析小偏置碰撞过程中乘员模型的运动学响应与损伤风险差异.与HybridⅢ假人相比,THOR躯干的整体运动趋势与THUMS近似.在损伤方面,THOR头部、脑部和下肢部位的损伤风险与THUMS更接近.THOR胸部整体压缩量要高于HybridⅢ假人和THUMS 10 mm左右;颈部损伤风险大体介于HybridⅢ假人和THUMS中间,更接近THUMS.结果表明,THOR在小偏置碰撞过程中表现出的运动趋势与预测损伤风险的能力与THUMS更接近,与HybridⅢ假人相比,在小偏置碰撞过程中展现出了更高的生物逼真度.展开更多
Supercapacitors are gaining popularity due to their high cycling stability,power density,and fast charge and discharge rates.Researchers are ex-ploring electrode materials,electrolytes,and separat-ors for cost-effecti...Supercapacitors are gaining popularity due to their high cycling stability,power density,and fast charge and discharge rates.Researchers are ex-ploring electrode materials,electrolytes,and separat-ors for cost-effective energy storage systems.Ad-vances in materials science have led to the develop-ment of hybrid nanomaterials,such as combining fil-amentous carbon forms with inorganic nanoparticles,to create new charge and energy transfer processes.Notable materials for electrochemical energy-stor-age applications include MXenes,2D transition met-al carbides,and nitrides,carbon black,carbon aerogels,activated carbon,carbon nanotubes,conducting polymers,carbon fibers,and nanofibers,and graphene,because of their thermal,electrical,and mechanical properties.Carbon materials mixed with conducting polymers,ceramics,metal oxides,transition metal oxides,metal hydroxides,transition metal sulfides,trans-ition metal dichalcogenide,metal sulfides,carbides,nitrides,and biomass materials have received widespread attention due to their remarkable performance,eco-friendliness,cost-effectiveness,and renewability.This article explores the development of carbon-based hybrid materials for future supercapacitors,including electric double-layer capacitors,pseudocapacitors,and hy-brid supercapacitors.It investigates the difficulties that influence structural design,manufacturing(electrospinning,hydro-thermal/solvothermal,template-assisted synthesis,electrodeposition,electrospray,3D printing)techniques and the latest car-bon-based hybrid materials research offer practical solutions for producing high-performance,next-generation supercapacitors.展开更多
Present of wind power is sporadically and cannot be utilized as the only fundamental load of energy sources.This paper proposes a wind-solar hybrid energy storage system(HESS)to ensure a stable supply grid for a longe...Present of wind power is sporadically and cannot be utilized as the only fundamental load of energy sources.This paper proposes a wind-solar hybrid energy storage system(HESS)to ensure a stable supply grid for a longer period.A multi-objective genetic algorithm(MOGA)and state of charge(SOC)region division for the batteries are introduced to solve the objective function and configuration of the system capacity,respectively.MATLAB/Simulink was used for simulation test.The optimization results show that for a 0.5 MW wind power and 0.5 MW photovoltaic system,with a combination of a 300 Ah lithium battery,a 200 Ah lead-acid battery,and a water storage tank,the proposed strategy reduces the system construction cost by approximately 18,000 yuan.Additionally,the cycle count of the electrochemical energy storage systemincreases from4515 to 4660,while the depth of discharge decreases from 55.37%to 53.65%,achieving shallow charging and discharging,thereby extending battery life and reducing grid voltage fluctuations significantly.The proposed strategy is a guide for stabilizing the grid connection of wind and solar power generation,capability allocation,and energy management of energy conservation systems.展开更多
The new energy power generation is becoming increasingly important in the power system.Such as photovoltaic power generation has become a research hotspot,however,due to the characteristics of light radiation changes,...The new energy power generation is becoming increasingly important in the power system.Such as photovoltaic power generation has become a research hotspot,however,due to the characteristics of light radiation changes,photovoltaic power generation is unstable and random,resulting in a low utilization rate and directly affecting the stability of the power grid.To solve this problem,this paper proposes a coordinated control strategy for a newenergy power generation system with a hybrid energy storage unit based on the lithium iron phosphate-supercapacitor hybrid energy storage unit.Firstly,the variational mode decomposition algorithm is used to separate the high and low frequencies of the power signal,which is conducive to the rapid and accurate suppression of the power fluctuation of the energy storage system.Secondly,the fuzzy control algorithm is introduced to balance the power between energy storage.In this paper,the actual data is used for simulation,and the simulation results show that the strategy realizes the effective suppression of the bus voltage fluctuation and the accurate control of the internal state of the energy storage unit,effectively avoiding problems such as overshoot and over-discharge,and can significantly improve the stability of the photovoltaic power generation systemand the stability of the Direct Current bus.It is of great significance to promote the development of collaborative control technology for photovoltaic hybrid energy storage units.展开更多
Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other...Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other fields.In recent years,with the continuous increase in demand for medium-thick plate titanium alloys,corresponding welding technologies have also continued to develop.Therefore,this article reviews the research progress of deep penetration welding technology for medium-thick plate titanium alloys,mainly covering traditional arc welding,high-energy beam welding,and other welding technologies.Among many methods,narrow gap welding,hybrid welding,and external energy field assistance welding all contribute to improving the welding efficiency and quality of medium-thick plate titanium alloys.Finally,the development trend of deep penetration welding technology for mediumthick plate titanium alloys is prospected.展开更多
Power quality is a crucial area of research in contemporary power systems,particularly given the rapid proliferation of intermittent renewable energy sources such as wind power.This study investigated the relationship...Power quality is a crucial area of research in contemporary power systems,particularly given the rapid proliferation of intermittent renewable energy sources such as wind power.This study investigated the relationships between power quality indices of system output and PSD by utilizing theories related to spectra,PSD,and random signal power spectra.The relationship was derived,validated through experiments and simulations,and subsequently applied to multi-objective optimization.Various optimization algorithms were compared to achieve optimal system power quality.The findings revealed that the relationships between power quality indices and PSD were influenced by variations in the order of the power spectral estimation model.An increase in the order of the AR model resulted in a 36%improvement in the number of optimal solutions.Regarding optimal solution distribution,NSGA-II demonstrated superior diversity,while MOEA/D exhibited better convergence.However,practical applications showed that while MOEA/D had higher convergence,NSGA-II produced superior optimal solutions,achieving the best power quality indices(THDi at 4.62%,d%at 3.51%,and cosφat 96%).These results suggest that the proposed method holds significant potential for optimizing power quality in practical applications.展开更多
Capacitive pressure sensors have a promising application in the field of wearable electronic devices due to their excellent electrical properties.Owing to the complexity of the environment,capacitive sensors are susce...Capacitive pressure sensors have a promising application in the field of wearable electronic devices due to their excellent electrical properties.Owing to the complexity of the environment,capacitive sensors are susceptible to electromagnetic interference and changes in the surrounding medium,resulting in unstable signal acquisition.Capacitive sensor with excellent immunity to interference while maintaining flexibility is an urgent challenge.This study proposes an all-fiber anti-jamming capacitive pressure sensor that integrates liquid metal(LM)into a fiber-based dielectric layer.The combination of the LM and the fiber not only improves the dielectric properties of the dielectric layer but also reduces the Young's modulus of the fiber.The sensor has high interference immunity in various noise environments.Its all-fiber structure ensures lightweight,great air permeability and stretchability,whichmakes it a promising application in wearable electronic devices fields.展开更多
3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have...3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have been limited. This study explores the impact of poly(vinylidene fluoride) and polydopamine-coated aluminum particles on the thermal and combustion properties of 3D printed hybrid rocket fuels. Physical self-assembly and anti-solvent methods were employed for constructing composite μAl particles. Characterization using SEM, XRD, XPS, FTIR, and μCT revealed a core-shell structure and homogeneous elemental distribution. Thermal analysis showed that PVDF coatings significantly increased the heat of combustion for aluminum particles, with maximum enhancement observed in μAl@PDA@PVDF(denoted as μAl@PF) at 6.20 k J/g. Subsequently, 3D printed fuels with varying pure and composite μAl particle contents were prepared using 3D printing. Combustion tests indicated higher regression rates for Al@PF/Resin composites compared to pure resin, positively correlating with particle content. The fluorocarbon-alumina reaction during the combustion stage intensified Al particle combustion, reducing residue size. A comprehensive model based on experiments provides insights into the combustion process of PDA and PVDF-coated droplets. This study advances the design of 3D-printed hybrid rocket fuels, offering strategies to improve regression rates and energy release, crucial for enhancing solid fuel performance for hybrid propulsion.展开更多
Graphite-silicon species(Gr-Si)hybrid anodes have merged as potential candidates for high-energy lithium-ion batteries(LIBs),yet long been plagued by rapid capacity fading due to their unstable mechano-electrochemistr...Graphite-silicon species(Gr-Si)hybrid anodes have merged as potential candidates for high-energy lithium-ion batteries(LIBs),yet long been plagued by rapid capacity fading due to their unstable mechano-electrochemistry.The dominant approach to enhance electrochemical stability of the Gr-Si hybrid anodes typically involves the optimization of the electrode material structures and the employment of low active Si species content in electrode(<10 wt%in most instances).However,the electrode structure design,a factor of equal importance in determining the electrochemical performance of Gr-Si hybrid anodes,has received scant attention.In this study,three Gr-Si hybrid anodes with the identical material composition but distinct electrode structures are designed to investigate the mechanoelectrochemistry of the electrodes.It is revealed that the substantial volume change of Si species particles in Gr-Si hybrid anodes led to the local lattice stress of Gr at their contact interface during the charge/discharge processes,thereby increasing thermodynamic and kinetic barrier of Li-ion migration.Furthermore,the huge disparity in volume change of Si species and Gr particles trigger the separate agglomeration of these two materials,resulting in a considerable electrode volume change and increased electrochemical resistance.An advanced Gr/Si hybrid anode with upper Gr and lower Si species layer structure design addresses the above challenges using photovoltaic waste silicon sources under high Si species content(17 wt%)and areal capacity(2.0 mA h cm^(-2))in Ah-level full pouch cells with a low negative/positive(N/P)ratio of 1.09.The cell shows stable cycling for 100 cycles at 0.3 C with an impressively low capacity decay rate of 0.0546%per cycle,outperforming most reported Gr-Si hybrid anodes.展开更多
Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is a highly successful conductive polymer utilized as an electrode material in energy storage units for portable and wearable electronic de-vices.Neve...Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is a highly successful conductive polymer utilized as an electrode material in energy storage units for portable and wearable electronic de-vices.Nevertheless,employing PEDOT:PSS in supercapacitors(SC)in its pristine state presents challenges due to its suboptimal electrochemical performance and operational instability.To surmount these limita-tions,PEDOT:PSS has been integrated with carbon-based materials to form flexible electrodes,which ex-hibit physical and chemical stability during SC operation.We developed a streamlined fabrication process for high-performance SC electrodes composed of PEDOT:PSS and carbon quantum dots(CQDs).The CQDs were synthesized under microwave irradiation,yielding green-and red-light emissions.Through optimiz-ing the ratios of CQDs to PEDOT:PSS,the SC electrodes were prepared using a spray-coating technique,marking a significant improvement in device performance with a high volumetric capacitance(104.10 F cm-3),impressive energy density(19.68 Wh cm^(-3)),and excellent cyclic stability,retaining~85% of its original volumetric capacitance after 15,000 repeated GCD cycles.Moreover,the SCs,when utilized as a flexible substrate,demonstrated the ability to maintain up to~85% of their electrochemical performance even after 3,000 bending cycles(at a bending angle of 60°).These attributes render this hybrid composite an ideal candidate for a lightweight smart energy storage component in portable and wearable electronic technologies.展开更多
基金supported by the Second Tibetan Plateau Scientific Expedition and Research program (No. 2019QZKK0502)Strategic Priority Research Program of Chinese Academy of Sciences (No. XDB31010300)+1 种基金Fundamental Research Funds for the Central UniversitiesInternational Collaboration 111 Program (BP0719040)。
文摘The identification and understanding of cryptic intraspecific evolutionary units(lineages) are crucial for planning effective conservation strategies aimed at preserving genetic diversity in endangered species.However, the factors driving the evolution and maintenance of these intraspecific lineages in most endangered species remain poorly understood. In this study, we conducted resequencing of 77 individuals from 22 natural populations of Davidia involucrata, a “living fossil” dove tree endemic to central and southwest China. Our analysis revealed the presence of three distinct local lineages within this endangered species, which emerged approximately 3.09 and 0.32 million years ago. These divergence events align well with the geographic and climatic oscillations that occurred across the distributional range.Additionally, we observed frequent hybridization events between the three lineages, resulting in the formation of hybrid populations in their adjacent as well as disjunct regions. These hybridizations likely arose from climate-driven population expansion and/or long-distance gene flow. Furthermore, we identified numerous environment-correlated gene variants across the total and many other genes that exhibited signals of positive evolution during the maintenance of two major local lineages. Our findings shed light on the highly dynamic evolution underlying the remarkably similar phenotype of this endangered species. Importantly, these results not only provide guidance for the development of conservation plans but also enhance our understanding of evolutionary past for this and other endangered species with similar histories.
基金supported by the Guangdong Provincial Key Project of Natural Science Foundation, China (Grant No. 021037)Guangdong Province Natural Science Foundation, China (Grant No. 7301008)+1 种基金South China Agricultural University President Foundation, China (Grant No. 2007K036)The Confocal Laser Scanning Microscope was provided by the Testing Center of South China Agricultural University, Guangzhou, China
文摘As maternal parents, diploid （L202-2x） and autotetraploid （L202-4x） of Oryza sativa cv. L2O2 were crossed with O. officinalis. Embryo development and fertilization in these two crosses were comparatively studied. There were no mature hybrid seeds obtained because all the hybridized spikelets died 30 days after pollination. The main reasons for no seed set were abnormal fertilization and development of the embryos and endosperms in the interspecific hybrids. There were doublefertilization, egg cell single-fertilization and non-fertilization in these crosses. Although 59.45% and 54.87% of hybrid embryos produced in the crosses of L202-2x/O. officinalis and L202-4x/O. officinalis, respectively, hybrid embryos ceased to develop or degenerated and plenty of free endosperm nuclei were in disaggregating state without developing cellular endosperms three days after pollination. Besides, some embryological differences in these two crosses were found, that is, the rate of double-fertilization and total rate of doubleand single-fertilization in L202-2x/O. officinalis were higher than those in L202-4x/O. officinalis. The embryo and endosperm of hybrids developed more slowly, and embryos and free endosperm nuclei were more severely degenerated in L202-4x/O. officinalis than in L202-2x/O. officinalis. Five days after pollination, a few of embryos in L202-2x/O. officinalis developed into pear-shaped ones, however, embryos in L202-4x/O. officinalis were all degenerated. Therefore, it is more difficult to obtain interspecific hybrids by wide crosses between autotetraploid of O. sativa and O. officinalis.
基金supported by the Natural Science Foundation of Jilin Province(20220101051JC)the National Natural Science Foundation of China(22075099)。
文摘Single-atom catalysts(SACs)are rapidly standing at the forefront of catalytic development due to their unique structures with significantly different catalytic activity,selectivity,and stability from conventional nanocatalysts.The electronic properties and catalytic performances of SACs hinge on the results of orbital hybridization of isolated central atoms with ligand atoms as well as of central atoms with bonding atoms provided by intermediates.Therefore,we conduct multifaceted explorations around orbital hybridizations in single-atom catalysis to elucidate the structure-activity relationships.Firstly,we introduce the basic theoretical knowledge related to orbital hybridizations,and summarize the main descriptors of orbital hybridizations,focusing on the discussion of the types of orbital hybridizations in singleatom catalysis.Then,we briefly sum up the application of orbital hybridizations in single-atom electrocatalysis and put forward important strategies for regulating orbital hybridizations in SACs to improve the catalytic performances.Finally,we present a personal perspective on the future challenges and opportunities of orbital hybridizations in single-atom catalysis.
文摘为探究混合Ⅲ(HybridⅢ)假人与人体乘员约束测试装置(test device for human occupant restraint,THOR)在小偏置碰撞试验中的生物逼真度差异,对比分析了HybridⅢ假人、THOR和人体安全模型(total human model for safety,THUMS)3种乘员模型在不同小偏置碰撞模式下的碰撞响应情况.采用有限元数值模拟方法,以吸能与侧滑两种典型小偏置碰撞模式的整车模型在碰撞过程中的脉冲曲线作为边界条件;结合包含完整内饰结构的某中型轿车驾驶舱模型和HybridⅢ假人、THOR以及THUMS,构建驾驶员侧约束系统仿真模型,分析小偏置碰撞过程中乘员模型的运动学响应与损伤风险差异.与HybridⅢ假人相比,THOR躯干的整体运动趋势与THUMS近似.在损伤方面,THOR头部、脑部和下肢部位的损伤风险与THUMS更接近.THOR胸部整体压缩量要高于HybridⅢ假人和THUMS 10 mm左右;颈部损伤风险大体介于HybridⅢ假人和THUMS中间,更接近THUMS.结果表明,THOR在小偏置碰撞过程中表现出的运动趋势与预测损伤风险的能力与THUMS更接近,与HybridⅢ假人相比,在小偏置碰撞过程中展现出了更高的生物逼真度.
文摘Supercapacitors are gaining popularity due to their high cycling stability,power density,and fast charge and discharge rates.Researchers are ex-ploring electrode materials,electrolytes,and separat-ors for cost-effective energy storage systems.Ad-vances in materials science have led to the develop-ment of hybrid nanomaterials,such as combining fil-amentous carbon forms with inorganic nanoparticles,to create new charge and energy transfer processes.Notable materials for electrochemical energy-stor-age applications include MXenes,2D transition met-al carbides,and nitrides,carbon black,carbon aerogels,activated carbon,carbon nanotubes,conducting polymers,carbon fibers,and nanofibers,and graphene,because of their thermal,electrical,and mechanical properties.Carbon materials mixed with conducting polymers,ceramics,metal oxides,transition metal oxides,metal hydroxides,transition metal sulfides,trans-ition metal dichalcogenide,metal sulfides,carbides,nitrides,and biomass materials have received widespread attention due to their remarkable performance,eco-friendliness,cost-effectiveness,and renewability.This article explores the development of carbon-based hybrid materials for future supercapacitors,including electric double-layer capacitors,pseudocapacitors,and hy-brid supercapacitors.It investigates the difficulties that influence structural design,manufacturing(electrospinning,hydro-thermal/solvothermal,template-assisted synthesis,electrodeposition,electrospray,3D printing)techniques and the latest car-bon-based hybrid materials research offer practical solutions for producing high-performance,next-generation supercapacitors.
基金supported by a Horizontal Project on the Development of a Hybrid Energy Storage Simulation Model for Wind Power Based on an RT-LAB Simulation System(PH2023000190)the Inner Mongolia Natural Science Foundation Project and the Optimization of Exergy Efficiency of a Hybrid Energy Storage System with Crossover Control for Wind Power(2023JQ04).
文摘Present of wind power is sporadically and cannot be utilized as the only fundamental load of energy sources.This paper proposes a wind-solar hybrid energy storage system(HESS)to ensure a stable supply grid for a longer period.A multi-objective genetic algorithm(MOGA)and state of charge(SOC)region division for the batteries are introduced to solve the objective function and configuration of the system capacity,respectively.MATLAB/Simulink was used for simulation test.The optimization results show that for a 0.5 MW wind power and 0.5 MW photovoltaic system,with a combination of a 300 Ah lithium battery,a 200 Ah lead-acid battery,and a water storage tank,the proposed strategy reduces the system construction cost by approximately 18,000 yuan.Additionally,the cycle count of the electrochemical energy storage systemincreases from4515 to 4660,while the depth of discharge decreases from 55.37%to 53.65%,achieving shallow charging and discharging,thereby extending battery life and reducing grid voltage fluctuations significantly.The proposed strategy is a guide for stabilizing the grid connection of wind and solar power generation,capability allocation,and energy management of energy conservation systems.
基金supported by the State Grid Corporation of China Science and Technology Project,grant number 52270723000900K.
文摘The new energy power generation is becoming increasingly important in the power system.Such as photovoltaic power generation has become a research hotspot,however,due to the characteristics of light radiation changes,photovoltaic power generation is unstable and random,resulting in a low utilization rate and directly affecting the stability of the power grid.To solve this problem,this paper proposes a coordinated control strategy for a newenergy power generation system with a hybrid energy storage unit based on the lithium iron phosphate-supercapacitor hybrid energy storage unit.Firstly,the variational mode decomposition algorithm is used to separate the high and low frequencies of the power signal,which is conducive to the rapid and accurate suppression of the power fluctuation of the energy storage system.Secondly,the fuzzy control algorithm is introduced to balance the power between energy storage.In this paper,the actual data is used for simulation,and the simulation results show that the strategy realizes the effective suppression of the bus voltage fluctuation and the accurate control of the internal state of the energy storage unit,effectively avoiding problems such as overshoot and over-discharge,and can significantly improve the stability of the photovoltaic power generation systemand the stability of the Direct Current bus.It is of great significance to promote the development of collaborative control technology for photovoltaic hybrid energy storage units.
基金financially supported by the Key Research and Development Program of Ningbo(Grant No.2023Z098)Natural Science Foundation of Inner Mongolia(Grant No.2023MS05040)+1 种基金Shenyang Collaborative Innovation Center Project for Multiple Energy Fields Composite Processing of Special Materials(Grant No.JG210027)Shenyang Key Technology Special Project of The Open Competition Mechanism to Select the Best Solution(Grant Nos.2022210101000827,2022-0-43-048).
文摘Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other fields.In recent years,with the continuous increase in demand for medium-thick plate titanium alloys,corresponding welding technologies have also continued to develop.Therefore,this article reviews the research progress of deep penetration welding technology for medium-thick plate titanium alloys,mainly covering traditional arc welding,high-energy beam welding,and other welding technologies.Among many methods,narrow gap welding,hybrid welding,and external energy field assistance welding all contribute to improving the welding efficiency and quality of medium-thick plate titanium alloys.Finally,the development trend of deep penetration welding technology for mediumthick plate titanium alloys is prospected.
基金funded by the Inner Mongolia Nature Foundation Project,Project number:2023JQ04.
文摘Power quality is a crucial area of research in contemporary power systems,particularly given the rapid proliferation of intermittent renewable energy sources such as wind power.This study investigated the relationships between power quality indices of system output and PSD by utilizing theories related to spectra,PSD,and random signal power spectra.The relationship was derived,validated through experiments and simulations,and subsequently applied to multi-objective optimization.Various optimization algorithms were compared to achieve optimal system power quality.The findings revealed that the relationships between power quality indices and PSD were influenced by variations in the order of the power spectral estimation model.An increase in the order of the AR model resulted in a 36%improvement in the number of optimal solutions.Regarding optimal solution distribution,NSGA-II demonstrated superior diversity,while MOEA/D exhibited better convergence.However,practical applications showed that while MOEA/D had higher convergence,NSGA-II produced superior optimal solutions,achieving the best power quality indices(THDi at 4.62%,d%at 3.51%,and cosφat 96%).These results suggest that the proposed method holds significant potential for optimizing power quality in practical applications.
基金financially supported by the National Natural Science Foundation of China(Nos.U20A20166,52371202,52125205,52250398,52192614 and 52003101)the National Key R&D Program of China(No.2021YFB3200300)+2 种基金the Natural Science Foundation of Beijing Municipality(No.2222088)Shenzhen Science and Technology Program(No.KQTD20170810105439418)the Fundamental Research Funds for the Central Universities
文摘Capacitive pressure sensors have a promising application in the field of wearable electronic devices due to their excellent electrical properties.Owing to the complexity of the environment,capacitive sensors are susceptible to electromagnetic interference and changes in the surrounding medium,resulting in unstable signal acquisition.Capacitive sensor with excellent immunity to interference while maintaining flexibility is an urgent challenge.This study proposes an all-fiber anti-jamming capacitive pressure sensor that integrates liquid metal(LM)into a fiber-based dielectric layer.The combination of the LM and the fiber not only improves the dielectric properties of the dielectric layer but also reduces the Young's modulus of the fiber.The sensor has high interference immunity in various noise environments.Its all-fiber structure ensures lightweight,great air permeability and stretchability,whichmakes it a promising application in wearable electronic devices fields.
基金funded by the National Natural Science Foundation of China(Grant No.06101213)the National Natural Science Foundation of China(Grant No.22105160).
文摘3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have been limited. This study explores the impact of poly(vinylidene fluoride) and polydopamine-coated aluminum particles on the thermal and combustion properties of 3D printed hybrid rocket fuels. Physical self-assembly and anti-solvent methods were employed for constructing composite μAl particles. Characterization using SEM, XRD, XPS, FTIR, and μCT revealed a core-shell structure and homogeneous elemental distribution. Thermal analysis showed that PVDF coatings significantly increased the heat of combustion for aluminum particles, with maximum enhancement observed in μAl@PDA@PVDF(denoted as μAl@PF) at 6.20 k J/g. Subsequently, 3D printed fuels with varying pure and composite μAl particle contents were prepared using 3D printing. Combustion tests indicated higher regression rates for Al@PF/Resin composites compared to pure resin, positively correlating with particle content. The fluorocarbon-alumina reaction during the combustion stage intensified Al particle combustion, reducing residue size. A comprehensive model based on experiments provides insights into the combustion process of PDA and PVDF-coated droplets. This study advances the design of 3D-printed hybrid rocket fuels, offering strategies to improve regression rates and energy release, crucial for enhancing solid fuel performance for hybrid propulsion.
基金the financial support by the National Natural Science Foundation of China(52072137)the National Natural Science Foundation of China(22205068)the"CUG Scholar"Scientific Research Funds at China University of Geosciences(Wuhan)(2022118)。
文摘Graphite-silicon species(Gr-Si)hybrid anodes have merged as potential candidates for high-energy lithium-ion batteries(LIBs),yet long been plagued by rapid capacity fading due to their unstable mechano-electrochemistry.The dominant approach to enhance electrochemical stability of the Gr-Si hybrid anodes typically involves the optimization of the electrode material structures and the employment of low active Si species content in electrode(<10 wt%in most instances).However,the electrode structure design,a factor of equal importance in determining the electrochemical performance of Gr-Si hybrid anodes,has received scant attention.In this study,three Gr-Si hybrid anodes with the identical material composition but distinct electrode structures are designed to investigate the mechanoelectrochemistry of the electrodes.It is revealed that the substantial volume change of Si species particles in Gr-Si hybrid anodes led to the local lattice stress of Gr at their contact interface during the charge/discharge processes,thereby increasing thermodynamic and kinetic barrier of Li-ion migration.Furthermore,the huge disparity in volume change of Si species and Gr particles trigger the separate agglomeration of these two materials,resulting in a considerable electrode volume change and increased electrochemical resistance.An advanced Gr/Si hybrid anode with upper Gr and lower Si species layer structure design addresses the above challenges using photovoltaic waste silicon sources under high Si species content(17 wt%)and areal capacity(2.0 mA h cm^(-2))in Ah-level full pouch cells with a low negative/positive(N/P)ratio of 1.09.The cell shows stable cycling for 100 cycles at 0.3 C with an impressively low capacity decay rate of 0.0546%per cycle,outperforming most reported Gr-Si hybrid anodes.
基金supported by the National Research Foundation of Korea(NRF)through a grant provided by the Korean government(No.NRF-2021R1F1A1063451).
文摘Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is a highly successful conductive polymer utilized as an electrode material in energy storage units for portable and wearable electronic de-vices.Nevertheless,employing PEDOT:PSS in supercapacitors(SC)in its pristine state presents challenges due to its suboptimal electrochemical performance and operational instability.To surmount these limita-tions,PEDOT:PSS has been integrated with carbon-based materials to form flexible electrodes,which ex-hibit physical and chemical stability during SC operation.We developed a streamlined fabrication process for high-performance SC electrodes composed of PEDOT:PSS and carbon quantum dots(CQDs).The CQDs were synthesized under microwave irradiation,yielding green-and red-light emissions.Through optimiz-ing the ratios of CQDs to PEDOT:PSS,the SC electrodes were prepared using a spray-coating technique,marking a significant improvement in device performance with a high volumetric capacitance(104.10 F cm-3),impressive energy density(19.68 Wh cm^(-3)),and excellent cyclic stability,retaining~85% of its original volumetric capacitance after 15,000 repeated GCD cycles.Moreover,the SCs,when utilized as a flexible substrate,demonstrated the ability to maintain up to~85% of their electrochemical performance even after 3,000 bending cycles(at a bending angle of 60°).These attributes render this hybrid composite an ideal candidate for a lightweight smart energy storage component in portable and wearable electronic technologies.
