The shuttle effect is among the most characteristic and formidable challenges in the pursuit of high-performance lithium-sulfur(Li-S)batteries.Herein,phosphorylated cellulose nanofibers(pCNF)are intentionally engineer...The shuttle effect is among the most characteristic and formidable challenges in the pursuit of high-performance lithium-sulfur(Li-S)batteries.Herein,phosphorylated cellulose nanofibers(pCNF)are intentionally engineered to establish an ion-sieving barrier against polysulfide shuttling and thereby improve battery performance.The phosphorylation,involving the grafting of phosphate groups onto the cellulose backbone,imparts an exceptional electronegativity that repels the polysulfide anions from penetrating through the separator.Moreover,the electrolyte wettability and Li^(+)transfer can be significantly promoted by the polar nature of pCNF and the facile Li^(+)disassociation.As such,rational ion management is realized,contributing to enhanced reversibility in both sulfur and lithium electrochemistry.As a result,Li-S cells equipped with the self-standing pCNF separator demonstrate outstanding long-term cyclability with a minimum fading rate of 0.013%per cycle over 1000 cycles at 1 C,and a decent areal capacity of 5.37 mA h cm^(-2) even under elevated sulfur loading of 5.0 mg cm^(-2) and limited electrolyte of 6.0 mL g^(-1).This work provides a facile and effective pathway toward the well-tamed shuttle effect and highly durable Li-S batteries.展开更多
Recovery of the coal buried under buildings,railways and water bodies and the residual coal in irregularly arranged fully mechanized mining faces is a common engineering problem facing underground coal mining.In this ...Recovery of the coal buried under buildings,railways and water bodies and the residual coal in irregularly arranged fully mechanized mining faces is a common engineering problem facing underground coal mining.In this study,a mining technology of continuous driving and gangue backfilling(CDGB)was proposed.The technology,which can not only alleviate ground subsidence and gangue discharge,but also release the above-mentioned coals,contributes to green and efficient sustainable development of mining.The stability of the system of the solidified body-reserved coal pillar combination(S-C combination)is crucial to the CDGB technology.Therefore,it is of great significance to explore the mechanical and damage characteristics of S-C combination in the synergistic bearing process.First,four sets of differentshaped S-C combination specimens were fabricated and a S-C combination bearing structure in CDGB was constructed to explore the differences in mechanical characteristics and damage modes of different-shaped S-C combination specimens during CDGB.Subsequently,their surface strain field evolutions and acoustic emission(AE)response characteristics in the load-bearing process were obtained with the aid of the digital image correlation technique and the AE signal monitoring system.Furthermore,a damage evolution model based on AE parameters and mechanical parameters was established to clarify the damage evolution law.The following results were obtained:(1)The free area of S-C combination can serve as a quantitative index to evaluate the stability of the overburden control system;(2)The concept of critical value k of the free area was first proposed.When the free area exceeds the critical value k(free area ratio greater than 1.13),the deformation resistance and the free area changes becomes negatively correlated;(3)As the free area expands,the failure of the S-C combination specimen evolves from tensile failure to shear failure.The distribution characteristics of the axial strain field also verified such a change in the failure mode;(4)When the free area expands,the peak AE count gradually changes from“double peaks”to“a single peak”.In this process,the expansion of free area shortens the time for accumulating and releasing energy during loading.Micro cracks generated in the specimen change from a phased steep growth to a continuous increase,and the process in which micro cracks develop,converge,intersect and connect to form macro cracks accelerates.The damage evolution law concluded based on AE parameters and mechanical parameters can well characterize the damage evolution process of S-C combination,providing certain reference for the study on the synergistic bearing of S-C combination during CDGB.展开更多
The pollution of microplastics(MPs)in the ocean has become a serious matter of concern.The farmed seaweeds(Caulerpa lentillifera and Gracilaria tenuistipitata)were selected to study their ability of adsorption with tw...The pollution of microplastics(MPs)in the ocean has become a serious matter of concern.The farmed seaweeds(Caulerpa lentillifera and Gracilaria tenuistipitata)were selected to study their ability of adsorption with two typical classes of MPs(polyamides and polystyrene),thereby revealing the interaction between MPs and macroalgae and exploring novel methods of removing MPs from macroalgae.The results demonstrate that polyamides(PA)fibers had no effect on the various physiological parameters of both seaweeds(e.g.,relative growth rate,photosynthetic oxygen evolution rate,the contents of malondialdehyde and extracellular polymeric substances)after 7 days of exposure,except for the chlorophyll-a concentration.However,the effects of polystyrene(PS)particles on the algae were strongly associated with the concentration of MPs exposure.Exposed to the high concentration(100 mg/L)of PS particles,the relative growth rate of C.lentillifera and G.tenuistipitata decreased by 54.56% and 30.62%,respectively,compared to the control,while no significant(P>0.05)harmful effect of PS particles on seaweeds was observed in an environment with a low content of PS particles(25 mg/L).The PS particles in concentration of 100 mg/L significantly(P<0.05)inhibited photosynthetic oxygen evolution rate and extracellular polymeric substances(EPS)contents in both seaweeds,but increased malondialdehyde(MDA)contents.When exposed for 72 h,the MPs adhesion rate of G.tenuistipitata is higher than that of C.lentillifera,which might be due to the higher EPS content of G.tenuistipitata.The MPs desorption experiment indicated that the combination of dewatering and washing had the highest desorption rate of MPs which could reach to 91.45%and 87.23%for C.lentillifera and G.tenuistipitata,respectively.This research demonstrates the potential of macroalgae as a vector for MPs in aquatic environment and provides methodological insights into decontamination procedures for removing the MPs from macroalgae.展开更多
Lithium(Li)metal anodes have attracted extensive attention due to their ultrahigh theoretical capacity and low potential.However,the uneven deposition of Li near the unstable electrode/electrolyte interfaces leads to ...Lithium(Li)metal anodes have attracted extensive attention due to their ultrahigh theoretical capacity and low potential.However,the uneven deposition of Li near the unstable electrode/electrolyte interfaces leads to the growth of Li dendrites and the degradation of active electrodes.Herein,we directly fluorinate alkyne-containing conjugated microporous polymers(ACMPs)microspheres with fluorine gas(F_(2))to introduce a novel fluorinated interlayer as an interfacial stabilizer in lithium metal batteries.Using density functional theory methods,it is found that as-prepared fluorinated ACMP(FACMP)has abundant partially ionic C–F bonds.The C–F bonds with electrochemical lability yield remarkable lithiophilicity during cycling.The in situ reactions between the active C–F bonds and Li ions enable transfer of lithium fluoride microcrystals to the solid electrolyte interphase(SEI)layers,guaranteeing effective ionic distribution and smooth Li deposition.Consequently,Li metal electrodes with the fluorinated interlayers demonstrate excellent cycling performances in both half-batteries and full cells with a lithium bis(trifluoromethanesulfonyl)imide electrolyte as well as a nonfluorinated lithium bis(oxalate)borate electrolyte system.This strategy is highly significant in customizable SEI layers to stabilize electrode interfaces and ensure high utilization of Li metal anodes,especially in a nonfluorinated electrolyte.展开更多
The development of tellurium(Te)-based semiconductor nanomaterials for efficient light-to-heat conversion may offer an effective means of harvesting sunlight to address global energy concerns.However,the nanosized Te(...The development of tellurium(Te)-based semiconductor nanomaterials for efficient light-to-heat conversion may offer an effective means of harvesting sunlight to address global energy concerns.However,the nanosized Te(nano-Te)materials reported to date suffer from a series of drawbacks,including limited light absorption and a lack of surface structures.Herein,we report the preparation of nano-Te by electrochemical exfoliation using an electrolyzable room-temperature ionic liquid.Anions,cations,and their corresponding electrolytic products acting as chemical scissors can precisely intercalate and functionalize bulk Te.The resulting nano-Te has high morphological entropy,rich surface functional groups,and broad light absorption.We also constructed foam hydrogels based on poly(vinyl alcohol)/nano-Te,which achieved an evaporation rate and energy efficiency of 4.11 kg m^(−2)h^(−1)and 128%,respectively,under 1 sun irradiation.Furthermore,the evaporation rate was maintained in the range 2.5-3.0 kg m^(−2)h^(−1)outdoors under 0.5-1.0 sun,providing highly efficient evaporation under low light conditions.展开更多
Automation advancements prompts the extensive integration of collaborative robot(cobot)across a range of industries.Compared to the commonly used design approach of increasing the payload-to-weight ratio of cobot to e...Automation advancements prompts the extensive integration of collaborative robot(cobot)across a range of industries.Compared to the commonly used design approach of increasing the payload-to-weight ratio of cobot to enhance load capacity,equal attention should be paid to the dynamic response characteristics of cobot during the design process to make the cobot more flexible.In this paper,a new method for designing the drive train parameters of cobot is proposed.Firstly,based on the analysis of factors influencing the load capacity and dynamic response characteristics,design criteria for both aspects are established for cobot with all optimization design criteria normalized within the design domain.Secondly,with the cobot in the horizontal pose,the motor design scheme is discretized and it takes the joint motor diameter and gearbox speed ratio as optimization design variables.Finally,all the discrete values of the optimization objectives are obtained through the enumeration method and the Pareto front is used to select the optimal solution through multi-objective optimization.Base on the cobot design method proposed in this paper,a six-axis cobot is designed and compared with the commercial cobot.The result shows that the load capacity of the designed cobot in this paper reaches 8.4 kg,surpassing the 5 kg load capacity commercial cobot which is used as a benchmark.The minimum resonance frequency of the joints is 42.70 Hz.展开更多
Real-time interaction with uncertain and dynamic environments is essential for robotic systems to achieve functions such as visual perception,force interaction,spatial obstacle avoidance,and motion planning.To ensure ...Real-time interaction with uncertain and dynamic environments is essential for robotic systems to achieve functions such as visual perception,force interaction,spatial obstacle avoidance,and motion planning.To ensure the reliability and determinism of system execution,a flexible real-time control system architecture and interaction algorithm are required.The ROS framework was designed to improve the reusability of robotic software development by providing a distributed structure,hardware abstraction,message-passing mechanism,and application prototypes.Rich ecosystems for robotic development have been built around ROS1 and ROS2 architectures based on the Linux system.However,because of the fairness scheduling principle of the default Linux system design and the complexity of the kernel,the system does not have real-time computing.To achieve a balance between real-time and non-real-time computing,this paper uses the transmission mechanism of ROS2,combines it with the scheduling mechanism of the Linux operating system,and uses Preempt_RT to enhance the real-time computing of ROS1 and ROS2.The real-time performance evaluation of ROS1 and ROS2 is conducted from multiple perspectives,including throughput,transmission mode,QoS service quality,frequency,number of subscription nodes and EtherCAT master.This paper makes two significant contributions:firstly,it employs Preempt_RT to optimize the native ROS2 system,effectively enhancing the real-time performance of native ROS2 message transmission;secondly,it conducts a comprehensive evaluation of the real-time performance of both native and optimized ROS2 systems.This comparison elucidates the benefits of the optimized ROS2 architecture regarding real-time performance,with results vividly demonstrated through illustrative figures.展开更多
Perovskite nanocrystal(PNC)solids are promising materials for optoelectronic applications.Recent studies have shown that exciton diffusion in PNC solids occurs via alternate exciton hopping(EH)and photon recycling(PR)...Perovskite nanocrystal(PNC)solids are promising materials for optoelectronic applications.Recent studies have shown that exciton diffusion in PNC solids occurs via alternate exciton hopping(EH)and photon recycling(PR).The energy disorder induced by the size distribution is a common factor in PNC solids,and the impact of this energy disorder on the exciton diffusion remains unclear.Here,we investigated the exciton diffusion in CsPbBr3 NC solids with a Gaussian size distribution of 11.2±6.8 nm via steady and time-resolved photoluminescence(PL)spectroscopy with multiple detection bands in transmission mode.Our results indicated that exciton diffusion was controlled by a downhill transfer among the different energy sites through the disordered energy landscape,as confirmed by the accompanying low-temperature PL analysis.A detailed examination revealed that the acceptor distribution in tandem with the reabsorption coefficient determined the contribution of EH and PR to exciton transfer between different energy sites.Consequently,the exciton diffusion mechanism varied in PNC solids of different thicknesses:in a thin solid with a thickness of several hundred nanometers,the exciton transfer was dominated by efficient EH and PR from the high-energy sites to the lower-energy sites;in a few-micrometer-thick solid,transfer from the medium-energy sites toward the lower-energy sites also became prominent and occurred mainly through PR.These findings enhance the understanding of the vital role that the acceptor distribution plays in the exciton diffusion process in PNC solids,providing important insights for optoelectronic applications based on PNC solids.Our work also exploits the use of commonly available tools for in-depth exciton diffusion studies,which reveals the interior diffusion information that is usually hidden in surface sensitive PL imaging methods.展开更多
Clinical application of bare metal stents is constrained by the occurrence of instent restenosis,mainly due to the complex biomechanical environment in the body.Numerical simulation method was used to evaluate the eff...Clinical application of bare metal stents is constrained by the occurrence of instent restenosis,mainly due to the complex biomechanical environment in the body.Numerical simulation method was used to evaluate the effect of plaque composition on stent performance in a carotid artery.CT angiography(CTA)data were used as a reference,and zero-load state of the carotid artery was used to establish a 3D stenotic artery model.Different plaque compositions,calcified and hypo-cellular were defined in Model 1 and Model 2,respectively.Interactions between the stents and arterial tissues within the stent crimping-expansion process were analyzed to explore the effects of plaque composition on the mechanical parameters of carotid stents.Goodman diagram and fatigue safety factor(FSF)were analyzed to explore the effects of plaque composition on fatigue performance of a carotid stent in the stent service process.In the stent crimping-expansion process,the von Mises stress in the stent and the dog-boning ratio in Model 1 were higher than that in Model 2.The calcified plaque prevented the stent from expanding the stenotic vessel to a pre-set diameter.Thus,the risk of rupture in the calcified plaque was higher than that in the hypo-cellular plaque.Plaque also affected the stress/strain in the vessel wall,which was observed to be lower in Model 1 than in Model 2.This indicated that calcified plaque could decrease the stress-induced injury of arterial tissues.Within the stent service process,the stents used in these two models were predicted to not fail under fatigue rupture as calculated by the Goodman diagram.Additionally,the points closer to the fatigue limit were generally observed at the inner bend of the stent crowns.The FSF of the stent in Model 1 was lower than that in Model 2.The stent operating in the presence of calcified plaques suffered high risk of fractures.Reliability and fatigue performance of the stent were found to be associated with plaque composition.Hence,this study may provide stent designers an approach toward enhancing the mechanical reliability of a stent.展开更多
Lithium-sulfur batteries(LSBs)are promising candidates for next-generation high-efficiency energy storage,yet their practical implementation is seriously impeded by the parasitic shuttle effect and sluggish reaction k...Lithium-sulfur batteries(LSBs)are promising candidates for next-generation high-efficiency energy storage,yet their practical implementation is seriously impeded by the parasitic shuttle effect and sluggish reaction kinetics.Herein,we develop a unique Cu,Co layered double hydroxide(CuCo-LDH)with a hollow and hierarchical structure as an advanced electrocatalyst to tackle these challenges.Combining the compositional,architectural,and chemical advantages,the as-developed CuCo-LDH enables facile charge transfer,fully exposed active interfaces,and strong interactions with polysulfides via metal-sulfur bonding.When employed in the functional separator,a reliable polysulfide barrier can be established against the shuttling behavior,while the excellent catalytic activity realizes fast and efficient sulfur electrochemistry.As a result,the CuCo-LDH-based LSBs achieve a well-restrained capacity decay of 0.049%per cycle over 500 cycles together with a good rate capability up to 5 C.Moreover,a favorable areal capacity of 4.39 mAh cm^(-2) and decent cyclability are still attainable even under a high sulfur loading of 4.2 mg cm^(-2) and a low E/S ratio of 6 ml g^(−1).This work affords a feasible and instructive pathway toward advanced sulfur electrocatalysts as well as high-performance LSBs.展开更多
The teleoperation of a 6 degrees-of-freedom(DOF)manipulator is one of the basic methods to extend people’s capabilities in the wide variety of applications.The master interface based on the force/torque(FT)sensor cou...The teleoperation of a 6 degrees-of-freedom(DOF)manipulator is one of the basic methods to extend people’s capabilities in the wide variety of applications.The master interface based on the force/torque(FT)sensor could provide the full-dimension intuitive teleoperation of a 6-DOF robot since it has the ability to trigger 6-DOF command input.However,due to the force coupling,noise disturbance and unlimited input signals of the FT sensor,this force-sensed interface could not be widely used in practice.In this paper,we present an intuitive teleoperation method based on the FT sensor to overcome these challenges.In this method,the input signals from the force-sensed joystick were filtered and then processed to the force commands by force limit algorithm,with the merits of anti-interference,output limitation,and online velocity adjustment.Furthermore,based on the admittance control and position controller,the manipulator could be teleoperated by the force commands.Three experiments were conducted on our self-designed robotic system.The result of the first experiment shows that the interfered force from the force coupling could be effectively suppressed with the limitation of the input force through force limit algorithm.Then,a parameter was introduced in the other two experiments to adjust the velocity online practically with force limit algorithm.The proposed method could give a practical solution to the intuitive teleoperation based on the FT sensor.展开更多
Due to a higher operating temperature(≥800 ℃),Solar Particle Receiver(SPR)which uses particles as the working medium is considered as one of best candidates to improve the thermoelectric conversion efficiency of con...Due to a higher operating temperature(≥800 ℃),Solar Particle Receiver(SPR)which uses particles as the working medium is considered as one of best candidates to improve the thermoelectric conversion efficiency of concentrating solar power plants.In this paper,a quartz tube solid particle receiver model is fully developed by using the discretized lumped parameter method,in which the calculation process of particle temperature and thermal loss is clearly given.In order to improve the manipulation level of particle receiver during the operation,the dynamic characteristics of the quartz tube particle receiver are comprehensively studied by the disturbance test of selected input parameters.Besides,in order to grasp the influence rule of key parameters on the thermal performance of particle receiver,the key parameters'sensitivity analysis is also deeply studied.The results show that the particle outlet temperature can reach as high as 810 ℃ under a relatively small value of solar flux 600 kW/m^(2),but the receiver efficiency is only about 75%;Besides,the receiver efficiency shows a variation tendency that it rises first falls afterwards with the increase of incident solar flux.The validity of proposed model is verified by a heating experi-mental system with a single quartz tube,and the relative error is not more than 7.9%.The research results are beneficial for understanding the dynamic characteristics and designing the particle receiver.展开更多
Expansion of renewable energy could help realize the goals of peaking carbon dioxide emissions and carbon neutralization.Some existing grid dispatching methods integrating short-term renewable energy prediction and re...Expansion of renewable energy could help realize the goals of peaking carbon dioxide emissions and carbon neutralization.Some existing grid dispatching methods integrating short-term renewable energy prediction and reinforcement learning(RL)have been proven to alleviate the adverse impact of energy fluctuations risk.However,these methods omit long-term output prediction,which leads to stability and security problems on optimal power flow.This paper proposes a confidence estimation Transformer for long-term renewable energy forecasting in reinforcement learning-based power grid dispatching(Conformer-RLpatching).Conformer-RLpatching predicts long-term active output of each renewable energy generator with an enhanced Transformer to ensure stable operation of the hybrid energy grid and improve the utilization rate of renewable energy,thus boosting dispatching performance.Furthermore,a confidence estimation method is proposed to reduce the prediction error of renewable energy.Meanwhile,a dispatching necessity evaluation mechanism is put forward to decide whether the active output of a generator needs to be adjusted.Experiments carried out on the SG-126 power grid simulator show that Conformer-RLpatching achieves great improvement over the second best algorithm DDPG in security score by 25.8%and achieves a better total reward compared with the golden medal team in the power grid dispatching competition sponsored by State Grid Corporation of China under the same simulation environment.Codes are outsourced in https://github.com/BUPT-ANTlab/Conformer-RLpatching.展开更多
We report a high-stability ultrafast ultraviolet(UV)laser source at 352 nm by exploring an all-fiber,all-polarizationmaintaining(all-PM),Yb-doped femtosecond fiber laser at 1060 nm.The output power,pulse width,and opt...We report a high-stability ultrafast ultraviolet(UV)laser source at 352 nm by exploring an all-fiber,all-polarizationmaintaining(all-PM),Yb-doped femtosecond fiber laser at 1060 nm.The output power,pulse width,and optical spectrum width of the fiber laser are 6 W,244 fs,and 17.5 nm,respectively.The UV ultrashort pulses at a repetition rate of 28.9 MHz are generated by leveraging single-pass second-harmonic generation in a 1.3-mm-long BiB_(3)O_(6)(BIBO)and sum frequency generation in a 5.1-mm-long BIBO.The maximum UV output power is 596 mW.The root mean square error of the output power of UV pulses is 0.54%.This laser,with promising stability,is expected to be a nice source for frontier applications in the UV wavelength window.展开更多
Lithium(Li)metal is the most promising anode for improving the energy density of currently commercialized Li-ion batteries.However,its practical application is limited due to its high reactivity to electrolytes,which ...Lithium(Li)metal is the most promising anode for improving the energy density of currently commercialized Li-ion batteries.However,its practical application is limited due to its high reactivity to electrolytes,which induces severe electrolyte decomposition and Li-dendrite growth.Interphases are usually constructed on Li anode to address the above issue.Meanwhile,it is a big challenge to balance the stability and plating/stripping overpotential of Li anode.In this work,we report a novel strategy for constructing a highly stable and lowly polarized surface film on Li anode.A chemically and structurally unique film is formed by simply dropping a zinc trifluoromethanesulfonate[Zn(OTF)_(2)]and fluoroethylene carbonate(FEC)-containing solution onto Li anode.This unique film consists of inner nucleation sites and outer protection textures,mainly containing Li–Zn alloy and LiF/polymer,respectively.The former results from the preferential reduction of Zn(OTF)_(2),providing nucleation sites with low polarization for Li plating/stripping.In contrast,the latter arises from the subsequent reduction of FEC,providing protection for the underneath Li–Zn alloy and Li metal and ensuring the stability of Li anode.The Li anode with such a unique surface film exhibits excellent cycling stability and low plating/stripping overpotentials,which have been demonstrated using Li//Li symmetric and Li//LiFePO_(4)full cells.展开更多
Promoted by CuI/2-hydroxybenzohydrazide catalytic system,a variety of pyrrole-and imidazole-fused quinoxalines have been efficiently one-pot synthesized from pyrrole-/imidazole-2-carboxaldehyde and 2-haloanilines in m...Promoted by CuI/2-hydroxybenzohydrazide catalytic system,a variety of pyrrole-and imidazole-fused quinoxalines have been efficiently one-pot synthesized from pyrrole-/imidazole-2-carboxaldehyde and 2-haloanilines in moderate to excellent yields.展开更多
The kinetics oflignocellulose hydrolysis under the conditions of high temperature and dilute acid （mass fraction 0.05%） was investigated in this paper. By studying the reducing sugar concentration versus reaction te...The kinetics oflignocellulose hydrolysis under the conditions of high temperature and dilute acid （mass fraction 0.05%） was investigated in this paper. By studying the reducing sugar concentration versus reaction tempera ture （170℃-220℃） and reaction time （150-1800 s） during the hydrolysis process of five kinds of crop straw （rice, wheat, cotton, rape and corn）, the shrinking core model was established, and the differential equation of the model and its analytical solution were obtained. With a numerical calculation method, the kinetic equation was estimated, and the degradation of reducing sugar obeyed firstorder kinetics was obtained. The calculated results from the equations agreed well with the original experimental data. The calculation by the model showed that the reducing sugar concentration increases as the size of the particles decrease, and the uniform particles increase.展开更多
基金the financial support from the National Natural Science Foundation of China(22109072)the Natural Science Foundation of Jiangsu Province(BK20210349)+1 种基金the Fundamental Research Funds for the Central Universities(30922010304)the Open Fund of National Forestry and Grassland Administration Key Laboratory of Plant Fiber Functional Materials(2022KFJJ06)。
文摘The shuttle effect is among the most characteristic and formidable challenges in the pursuit of high-performance lithium-sulfur(Li-S)batteries.Herein,phosphorylated cellulose nanofibers(pCNF)are intentionally engineered to establish an ion-sieving barrier against polysulfide shuttling and thereby improve battery performance.The phosphorylation,involving the grafting of phosphate groups onto the cellulose backbone,imparts an exceptional electronegativity that repels the polysulfide anions from penetrating through the separator.Moreover,the electrolyte wettability and Li^(+)transfer can be significantly promoted by the polar nature of pCNF and the facile Li^(+)disassociation.As such,rational ion management is realized,contributing to enhanced reversibility in both sulfur and lithium electrochemistry.As a result,Li-S cells equipped with the self-standing pCNF separator demonstrate outstanding long-term cyclability with a minimum fading rate of 0.013%per cycle over 1000 cycles at 1 C,and a decent areal capacity of 5.37 mA h cm^(-2) even under elevated sulfur loading of 5.0 mg cm^(-2) and limited electrolyte of 6.0 mL g^(-1).This work provides a facile and effective pathway toward the well-tamed shuttle effect and highly durable Li-S batteries.
基金the National Natural Science Foundation of China(Nos.U21A20108,52322403,52174108,and 51974105)the Support Plan for Science&Technology Innovation Talents in Universities of Henan Province(No.21HASTIT024)+1 种基金the Scientific and technological innovation research team of Henan Polytechnic University(No.T2021-5)the Henan Excellent Youth Science Foundation(No.222300420045).
文摘Recovery of the coal buried under buildings,railways and water bodies and the residual coal in irregularly arranged fully mechanized mining faces is a common engineering problem facing underground coal mining.In this study,a mining technology of continuous driving and gangue backfilling(CDGB)was proposed.The technology,which can not only alleviate ground subsidence and gangue discharge,but also release the above-mentioned coals,contributes to green and efficient sustainable development of mining.The stability of the system of the solidified body-reserved coal pillar combination(S-C combination)is crucial to the CDGB technology.Therefore,it is of great significance to explore the mechanical and damage characteristics of S-C combination in the synergistic bearing process.First,four sets of differentshaped S-C combination specimens were fabricated and a S-C combination bearing structure in CDGB was constructed to explore the differences in mechanical characteristics and damage modes of different-shaped S-C combination specimens during CDGB.Subsequently,their surface strain field evolutions and acoustic emission(AE)response characteristics in the load-bearing process were obtained with the aid of the digital image correlation technique and the AE signal monitoring system.Furthermore,a damage evolution model based on AE parameters and mechanical parameters was established to clarify the damage evolution law.The following results were obtained:(1)The free area of S-C combination can serve as a quantitative index to evaluate the stability of the overburden control system;(2)The concept of critical value k of the free area was first proposed.When the free area exceeds the critical value k(free area ratio greater than 1.13),the deformation resistance and the free area changes becomes negatively correlated;(3)As the free area expands,the failure of the S-C combination specimen evolves from tensile failure to shear failure.The distribution characteristics of the axial strain field also verified such a change in the failure mode;(4)When the free area expands,the peak AE count gradually changes from“double peaks”to“a single peak”.In this process,the expansion of free area shortens the time for accumulating and releasing energy during loading.Micro cracks generated in the specimen change from a phased steep growth to a continuous increase,and the process in which micro cracks develop,converge,intersect and connect to form macro cracks accelerates.The damage evolution law concluded based on AE parameters and mechanical parameters can well characterize the damage evolution process of S-C combination,providing certain reference for the study on the synergistic bearing of S-C combination during CDGB.
基金Supported by the Key R&D Program of Hainan Province(No.ZDYF2020178)the Construction of Public Scientific Research Platform for Hydrobiology and Biotechnology,a Central-GovernmentLed Local Science and Technology Development Foundation(No.ZY2021HN04)。
文摘The pollution of microplastics(MPs)in the ocean has become a serious matter of concern.The farmed seaweeds(Caulerpa lentillifera and Gracilaria tenuistipitata)were selected to study their ability of adsorption with two typical classes of MPs(polyamides and polystyrene),thereby revealing the interaction between MPs and macroalgae and exploring novel methods of removing MPs from macroalgae.The results demonstrate that polyamides(PA)fibers had no effect on the various physiological parameters of both seaweeds(e.g.,relative growth rate,photosynthetic oxygen evolution rate,the contents of malondialdehyde and extracellular polymeric substances)after 7 days of exposure,except for the chlorophyll-a concentration.However,the effects of polystyrene(PS)particles on the algae were strongly associated with the concentration of MPs exposure.Exposed to the high concentration(100 mg/L)of PS particles,the relative growth rate of C.lentillifera and G.tenuistipitata decreased by 54.56% and 30.62%,respectively,compared to the control,while no significant(P>0.05)harmful effect of PS particles on seaweeds was observed in an environment with a low content of PS particles(25 mg/L).The PS particles in concentration of 100 mg/L significantly(P<0.05)inhibited photosynthetic oxygen evolution rate and extracellular polymeric substances(EPS)contents in both seaweeds,but increased malondialdehyde(MDA)contents.When exposed for 72 h,the MPs adhesion rate of G.tenuistipitata is higher than that of C.lentillifera,which might be due to the higher EPS content of G.tenuistipitata.The MPs desorption experiment indicated that the combination of dewatering and washing had the highest desorption rate of MPs which could reach to 91.45%and 87.23%for C.lentillifera and G.tenuistipitata,respectively.This research demonstrates the potential of macroalgae as a vector for MPs in aquatic environment and provides methodological insights into decontamination procedures for removing the MPs from macroalgae.
基金Science Foundation for Distinguished Young Scholars in Tianjin,Grant/Award Number:19JCJQJC61700National Natural Science Foundation of China,Grant/Award Numbers:51773147,51973151,52130303National Key R&D Program of China,Grant/Award Number:2022YFB3805702。
文摘Lithium(Li)metal anodes have attracted extensive attention due to their ultrahigh theoretical capacity and low potential.However,the uneven deposition of Li near the unstable electrode/electrolyte interfaces leads to the growth of Li dendrites and the degradation of active electrodes.Herein,we directly fluorinate alkyne-containing conjugated microporous polymers(ACMPs)microspheres with fluorine gas(F_(2))to introduce a novel fluorinated interlayer as an interfacial stabilizer in lithium metal batteries.Using density functional theory methods,it is found that as-prepared fluorinated ACMP(FACMP)has abundant partially ionic C–F bonds.The C–F bonds with electrochemical lability yield remarkable lithiophilicity during cycling.The in situ reactions between the active C–F bonds and Li ions enable transfer of lithium fluoride microcrystals to the solid electrolyte interphase(SEI)layers,guaranteeing effective ionic distribution and smooth Li deposition.Consequently,Li metal electrodes with the fluorinated interlayers demonstrate excellent cycling performances in both half-batteries and full cells with a lithium bis(trifluoromethanesulfonyl)imide electrolyte as well as a nonfluorinated lithium bis(oxalate)borate electrolyte system.This strategy is highly significant in customizable SEI layers to stabilize electrode interfaces and ensure high utilization of Li metal anodes,especially in a nonfluorinated electrolyte.
基金the Science and Technology Innovation Council of Shenzhen(Grant Nos.JCYJ20200109105212568,KQTD20170810105439418,JCYJ20200109114237902,20200812203318002,and 20200810103814002)the National Natural Science Foundation of China(Grant No.12274197)the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2023A1515030240,2019A1515010790,2021A0505110015).
文摘The development of tellurium(Te)-based semiconductor nanomaterials for efficient light-to-heat conversion may offer an effective means of harvesting sunlight to address global energy concerns.However,the nanosized Te(nano-Te)materials reported to date suffer from a series of drawbacks,including limited light absorption and a lack of surface structures.Herein,we report the preparation of nano-Te by electrochemical exfoliation using an electrolyzable room-temperature ionic liquid.Anions,cations,and their corresponding electrolytic products acting as chemical scissors can precisely intercalate and functionalize bulk Te.The resulting nano-Te has high morphological entropy,rich surface functional groups,and broad light absorption.We also constructed foam hydrogels based on poly(vinyl alcohol)/nano-Te,which achieved an evaporation rate and energy efficiency of 4.11 kg m^(−2)h^(−1)and 128%,respectively,under 1 sun irradiation.Furthermore,the evaporation rate was maintained in the range 2.5-3.0 kg m^(−2)h^(−1)outdoors under 0.5-1.0 sun,providing highly efficient evaporation under low light conditions.
基金Supported by National Key Research and Development Program of China (Grant Nos.2022YFB4703000,2019YFB1309900)。
文摘Automation advancements prompts the extensive integration of collaborative robot(cobot)across a range of industries.Compared to the commonly used design approach of increasing the payload-to-weight ratio of cobot to enhance load capacity,equal attention should be paid to the dynamic response characteristics of cobot during the design process to make the cobot more flexible.In this paper,a new method for designing the drive train parameters of cobot is proposed.Firstly,based on the analysis of factors influencing the load capacity and dynamic response characteristics,design criteria for both aspects are established for cobot with all optimization design criteria normalized within the design domain.Secondly,with the cobot in the horizontal pose,the motor design scheme is discretized and it takes the joint motor diameter and gearbox speed ratio as optimization design variables.Finally,all the discrete values of the optimization objectives are obtained through the enumeration method and the Pareto front is used to select the optimal solution through multi-objective optimization.Base on the cobot design method proposed in this paper,a six-axis cobot is designed and compared with the commercial cobot.The result shows that the load capacity of the designed cobot in this paper reaches 8.4 kg,surpassing the 5 kg load capacity commercial cobot which is used as a benchmark.The minimum resonance frequency of the joints is 42.70 Hz.
基金Supported by National Key Research and Development Program of China(Grant No.2019YFB1309900)Institute for Guo Qiang,Tsinghua University of China(Grant No.2019GQG0007).
文摘Real-time interaction with uncertain and dynamic environments is essential for robotic systems to achieve functions such as visual perception,force interaction,spatial obstacle avoidance,and motion planning.To ensure the reliability and determinism of system execution,a flexible real-time control system architecture and interaction algorithm are required.The ROS framework was designed to improve the reusability of robotic software development by providing a distributed structure,hardware abstraction,message-passing mechanism,and application prototypes.Rich ecosystems for robotic development have been built around ROS1 and ROS2 architectures based on the Linux system.However,because of the fairness scheduling principle of the default Linux system design and the complexity of the kernel,the system does not have real-time computing.To achieve a balance between real-time and non-real-time computing,this paper uses the transmission mechanism of ROS2,combines it with the scheduling mechanism of the Linux operating system,and uses Preempt_RT to enhance the real-time computing of ROS1 and ROS2.The real-time performance evaluation of ROS1 and ROS2 is conducted from multiple perspectives,including throughput,transmission mode,QoS service quality,frequency,number of subscription nodes and EtherCAT master.This paper makes two significant contributions:firstly,it employs Preempt_RT to optimize the native ROS2 system,effectively enhancing the real-time performance of native ROS2 message transmission;secondly,it conducts a comprehensive evaluation of the real-time performance of both native and optimized ROS2 systems.This comparison elucidates the benefits of the optimized ROS2 architecture regarding real-time performance,with results vividly demonstrated through illustrative figures.
基金financially supported by Shenzhen Fundamental Research Program(JCYJ20200109142425294)the National Natural Science Foundation of China(62034009 and 62104266)the Shenzhen Science and Technology Innovation Program(2022A006)。
文摘Perovskite nanocrystal(PNC)solids are promising materials for optoelectronic applications.Recent studies have shown that exciton diffusion in PNC solids occurs via alternate exciton hopping(EH)and photon recycling(PR).The energy disorder induced by the size distribution is a common factor in PNC solids,and the impact of this energy disorder on the exciton diffusion remains unclear.Here,we investigated the exciton diffusion in CsPbBr3 NC solids with a Gaussian size distribution of 11.2±6.8 nm via steady and time-resolved photoluminescence(PL)spectroscopy with multiple detection bands in transmission mode.Our results indicated that exciton diffusion was controlled by a downhill transfer among the different energy sites through the disordered energy landscape,as confirmed by the accompanying low-temperature PL analysis.A detailed examination revealed that the acceptor distribution in tandem with the reabsorption coefficient determined the contribution of EH and PR to exciton transfer between different energy sites.Consequently,the exciton diffusion mechanism varied in PNC solids of different thicknesses:in a thin solid with a thickness of several hundred nanometers,the exciton transfer was dominated by efficient EH and PR from the high-energy sites to the lower-energy sites;in a few-micrometer-thick solid,transfer from the medium-energy sites toward the lower-energy sites also became prominent and occurred mainly through PR.These findings enhance the understanding of the vital role that the acceptor distribution plays in the exciton diffusion process in PNC solids,providing important insights for optoelectronic applications based on PNC solids.Our work also exploits the use of commonly available tools for in-depth exciton diffusion studies,which reveals the interior diffusion information that is usually hidden in surface sensitive PL imaging methods.
基金supported by Major Project of Science and Technology of Beijing Municipal Education Commission and Type B Project of Beijing Natural Science Foundation(KZ201710005007).
文摘Clinical application of bare metal stents is constrained by the occurrence of instent restenosis,mainly due to the complex biomechanical environment in the body.Numerical simulation method was used to evaluate the effect of plaque composition on stent performance in a carotid artery.CT angiography(CTA)data were used as a reference,and zero-load state of the carotid artery was used to establish a 3D stenotic artery model.Different plaque compositions,calcified and hypo-cellular were defined in Model 1 and Model 2,respectively.Interactions between the stents and arterial tissues within the stent crimping-expansion process were analyzed to explore the effects of plaque composition on the mechanical parameters of carotid stents.Goodman diagram and fatigue safety factor(FSF)were analyzed to explore the effects of plaque composition on fatigue performance of a carotid stent in the stent service process.In the stent crimping-expansion process,the von Mises stress in the stent and the dog-boning ratio in Model 1 were higher than that in Model 2.The calcified plaque prevented the stent from expanding the stenotic vessel to a pre-set diameter.Thus,the risk of rupture in the calcified plaque was higher than that in the hypo-cellular plaque.Plaque also affected the stress/strain in the vessel wall,which was observed to be lower in Model 1 than in Model 2.This indicated that calcified plaque could decrease the stress-induced injury of arterial tissues.Within the stent service process,the stents used in these two models were predicted to not fail under fatigue rupture as calculated by the Goodman diagram.Additionally,the points closer to the fatigue limit were generally observed at the inner bend of the stent crowns.The FSF of the stent in Model 1 was lower than that in Model 2.The stent operating in the presence of calcified plaques suffered high risk of fractures.Reliability and fatigue performance of the stent were found to be associated with plaque composition.Hence,this study may provide stent designers an approach toward enhancing the mechanical reliability of a stent.
基金Outstanding Youth Project of Guangdong Natural Science Foundation(Grant No.2021B1515020051)Yunnan Expert Workstation(202005AF150028)+2 种基金National Natural Science Foundation of China(22109072)Natural Science Foundation of Jiangsu Province(BK20210349)Fundamental Research Funds for the Central Universities(No.30922010304).
文摘Lithium-sulfur batteries(LSBs)are promising candidates for next-generation high-efficiency energy storage,yet their practical implementation is seriously impeded by the parasitic shuttle effect and sluggish reaction kinetics.Herein,we develop a unique Cu,Co layered double hydroxide(CuCo-LDH)with a hollow and hierarchical structure as an advanced electrocatalyst to tackle these challenges.Combining the compositional,architectural,and chemical advantages,the as-developed CuCo-LDH enables facile charge transfer,fully exposed active interfaces,and strong interactions with polysulfides via metal-sulfur bonding.When employed in the functional separator,a reliable polysulfide barrier can be established against the shuttling behavior,while the excellent catalytic activity realizes fast and efficient sulfur electrochemistry.As a result,the CuCo-LDH-based LSBs achieve a well-restrained capacity decay of 0.049%per cycle over 500 cycles together with a good rate capability up to 5 C.Moreover,a favorable areal capacity of 4.39 mAh cm^(-2) and decent cyclability are still attainable even under a high sulfur loading of 4.2 mg cm^(-2) and a low E/S ratio of 6 ml g^(−1).This work affords a feasible and instructive pathway toward advanced sulfur electrocatalysts as well as high-performance LSBs.
基金National Key Research and Development Program of China(Grant No.2019YFB1309900)Shandong Provincial Key Research and Development Program of China(Grant No.2019JZZY010432)Institute for Guo Qiang,Tsinghua University,China(Grant No.2019GQG0007).
文摘The teleoperation of a 6 degrees-of-freedom(DOF)manipulator is one of the basic methods to extend people’s capabilities in the wide variety of applications.The master interface based on the force/torque(FT)sensor could provide the full-dimension intuitive teleoperation of a 6-DOF robot since it has the ability to trigger 6-DOF command input.However,due to the force coupling,noise disturbance and unlimited input signals of the FT sensor,this force-sensed interface could not be widely used in practice.In this paper,we present an intuitive teleoperation method based on the FT sensor to overcome these challenges.In this method,the input signals from the force-sensed joystick were filtered and then processed to the force commands by force limit algorithm,with the merits of anti-interference,output limitation,and online velocity adjustment.Furthermore,based on the admittance control and position controller,the manipulator could be teleoperated by the force commands.Three experiments were conducted on our self-designed robotic system.The result of the first experiment shows that the interfered force from the force coupling could be effectively suppressed with the limitation of the input force through force limit algorithm.Then,a parameter was introduced in the other two experiments to adjust the velocity online practically with force limit algorithm.The proposed method could give a practical solution to the intuitive teleoperation based on the FT sensor.
基金financial support provided by Beijing Municipal Natural Science Foundation“Study on the gas-solid heat transfer characteristics and enhancement mechanism of fluidized bed solid particle/sCO_(2) heat exchanger in solar thermal power plant”(No.3222033)by Chinese Universities Scientific Fund(No.15052003).
文摘Due to a higher operating temperature(≥800 ℃),Solar Particle Receiver(SPR)which uses particles as the working medium is considered as one of best candidates to improve the thermoelectric conversion efficiency of concentrating solar power plants.In this paper,a quartz tube solid particle receiver model is fully developed by using the discretized lumped parameter method,in which the calculation process of particle temperature and thermal loss is clearly given.In order to improve the manipulation level of particle receiver during the operation,the dynamic characteristics of the quartz tube particle receiver are comprehensively studied by the disturbance test of selected input parameters.Besides,in order to grasp the influence rule of key parameters on the thermal performance of particle receiver,the key parameters'sensitivity analysis is also deeply studied.The results show that the particle outlet temperature can reach as high as 810 ℃ under a relatively small value of solar flux 600 kW/m^(2),but the receiver efficiency is only about 75%;Besides,the receiver efficiency shows a variation tendency that it rises first falls afterwards with the increase of incident solar flux.The validity of proposed model is verified by a heating experi-mental system with a single quartz tube,and the relative error is not more than 7.9%.The research results are beneficial for understanding the dynamic characteristics and designing the particle receiver.
基金supported by the Basic Science (Natural science)Research Project of Higher Education of Jiangsu Province (Grant No.23KJB460019)the National Natural Science Foundation of China (Grant Nos.12302355 and 52075548)+2 种基金the Taishan Scholar Program of Shandong Province (Grant No.tsqn201909068)the Excellent Young Scientists Fund of Shandong Province (Grant No.2022HWYQ-071)the Fundamental Research Funds for the Central Universities (Grant No.20CX06074A)。
基金supported by the State Key Program of National Natural Science Foundation of China(Grant No.U1866210)supported by the National Natural Science Foundation of China(No.62176024)Open Fund of Beijing Key Laboratory of Research and System Evaluation of Power Dispatching Automation Technology(China Electric Power Research Institute)(No.DZB51202101268).
文摘Expansion of renewable energy could help realize the goals of peaking carbon dioxide emissions and carbon neutralization.Some existing grid dispatching methods integrating short-term renewable energy prediction and reinforcement learning(RL)have been proven to alleviate the adverse impact of energy fluctuations risk.However,these methods omit long-term output prediction,which leads to stability and security problems on optimal power flow.This paper proposes a confidence estimation Transformer for long-term renewable energy forecasting in reinforcement learning-based power grid dispatching(Conformer-RLpatching).Conformer-RLpatching predicts long-term active output of each renewable energy generator with an enhanced Transformer to ensure stable operation of the hybrid energy grid and improve the utilization rate of renewable energy,thus boosting dispatching performance.Furthermore,a confidence estimation method is proposed to reduce the prediction error of renewable energy.Meanwhile,a dispatching necessity evaluation mechanism is put forward to decide whether the active output of a generator needs to be adjusted.Experiments carried out on the SG-126 power grid simulator show that Conformer-RLpatching achieves great improvement over the second best algorithm DDPG in security score by 25.8%and achieves a better total reward compared with the golden medal team in the power grid dispatching competition sponsored by State Grid Corporation of China under the same simulation environment.Codes are outsourced in https://github.com/BUPT-ANTlab/Conformer-RLpatching.
基金partially supported by the National Natural Science Foundation of China(NSFC)(Nos.62375087,12374304,U1609219,and 62235014)the NSFC Development of National Major Scientific Research Instrument(No.61927816)+3 种基金the Mobility Programme of the Sino-German(No.M-0296)the Introduced Innovative Team Project of Guangdong Pearl River Talents Program(No.2021ZT09Z109)the Natural Science Foundation of Guangdong Province(No.2021B1515020074)the Science and Technology Project of Guangdong(No.2020B1212060002)。
文摘We report a high-stability ultrafast ultraviolet(UV)laser source at 352 nm by exploring an all-fiber,all-polarizationmaintaining(all-PM),Yb-doped femtosecond fiber laser at 1060 nm.The output power,pulse width,and optical spectrum width of the fiber laser are 6 W,244 fs,and 17.5 nm,respectively.The UV ultrashort pulses at a repetition rate of 28.9 MHz are generated by leveraging single-pass second-harmonic generation in a 1.3-mm-long BiB_(3)O_(6)(BIBO)and sum frequency generation in a 5.1-mm-long BIBO.The maximum UV output power is 596 mW.The root mean square error of the output power of UV pulses is 0.54%.This laser,with promising stability,is expected to be a nice source for frontier applications in the UV wavelength window.
基金supported by the National Key Research and Development Project of China(2018YFE0124800)。
文摘Lithium(Li)metal is the most promising anode for improving the energy density of currently commercialized Li-ion batteries.However,its practical application is limited due to its high reactivity to electrolytes,which induces severe electrolyte decomposition and Li-dendrite growth.Interphases are usually constructed on Li anode to address the above issue.Meanwhile,it is a big challenge to balance the stability and plating/stripping overpotential of Li anode.In this work,we report a novel strategy for constructing a highly stable and lowly polarized surface film on Li anode.A chemically and structurally unique film is formed by simply dropping a zinc trifluoromethanesulfonate[Zn(OTF)_(2)]and fluoroethylene carbonate(FEC)-containing solution onto Li anode.This unique film consists of inner nucleation sites and outer protection textures,mainly containing Li–Zn alloy and LiF/polymer,respectively.The former results from the preferential reduction of Zn(OTF)_(2),providing nucleation sites with low polarization for Li plating/stripping.In contrast,the latter arises from the subsequent reduction of FEC,providing protection for the underneath Li–Zn alloy and Li metal and ensuring the stability of Li anode.The Li anode with such a unique surface film exhibits excellent cycling stability and low plating/stripping overpotentials,which have been demonstrated using Li//Li symmetric and Li//LiFePO_(4)full cells.
基金the National Basic Research Program of China(973 Program,No.2012CB722603)the NSFC(Nos.21103114,21463022)and Training Program for Distinguished Youth Scholars of Shihezi University(No.2014ZRKXJQ05)for their financial support.
文摘Promoted by CuI/2-hydroxybenzohydrazide catalytic system,a variety of pyrrole-and imidazole-fused quinoxalines have been efficiently one-pot synthesized from pyrrole-/imidazole-2-carboxaldehyde and 2-haloanilines in moderate to excellent yields.
文摘The kinetics oflignocellulose hydrolysis under the conditions of high temperature and dilute acid （mass fraction 0.05%） was investigated in this paper. By studying the reducing sugar concentration versus reaction tempera ture （170℃-220℃） and reaction time （150-1800 s） during the hydrolysis process of five kinds of crop straw （rice, wheat, cotton, rape and corn）, the shrinking core model was established, and the differential equation of the model and its analytical solution were obtained. With a numerical calculation method, the kinetic equation was estimated, and the degradation of reducing sugar obeyed firstorder kinetics was obtained. The calculated results from the equations agreed well with the original experimental data. The calculation by the model showed that the reducing sugar concentration increases as the size of the particles decrease, and the uniform particles increase.
