It is regretful that the Acknowledgments part was lost in the final process of publication.The Acknowledgments part should be added as follow.The work described in this paper was supported by the grants from the Resea...It is regretful that the Acknowledgments part was lost in the final process of publication.The Acknowledgments part should be added as follow.The work described in this paper was supported by the grants from the Research Grants Council of the Hong Kong Special Administrative Region,China(Project No.16205721).展开更多
Chemical leaching of coals would be required to produce cleaner coals for some special applications where physical benefi-ciation may not be effective enough.This would also help in recovering Li and rare earth metals...Chemical leaching of coals would be required to produce cleaner coals for some special applications where physical benefi-ciation may not be effective enough.This would also help in recovering Li and rare earth metals besides in the sequestration of CO_(2).About 20 Indian coals having complexly distributed moderate to high ash contents were sequentially treated with various alkali–acid such as NaOH-HCl,HF,HCl,HCl-HF,and NaOH-HCl-HF leaching.This aimed to establish and design the best stepwise sequential process for the highest degree of demineralisation through a chemical leaching process.Kinetics and process intensification studies were carried out.More than 80%demineralisation of Madhaipur and Neemcha coals was observed using the best sequential treatment designed presently.The repeated stepwise treatment of the alkali and the acid was also studied,which was found to significantly enhance the degree of demineralisation of coals.The integrated process of alkali–acid leaching followed by solvent extraction(Organo-refining)and vice versa of the treated coal was also studied for producing cleaner coals.展开更多
For efficient colloidal quantum dot(CQD)solar cells(CQD-SCs),thiol-passivated p-type CQDs are generally used as a hole-transporting material(HTM);however,there are issues with the control of optoelectrical properties,...For efficient colloidal quantum dot(CQD)solar cells(CQD-SCs),thiol-passivated p-type CQDs are generally used as a hole-transporting material(HTM);however,there are issues with the control of optoelectrical properties,low thiol passivation rate,and poor morphology with a power conversion efficiency(PCE)of approximately 11%.Although polymeric HTMs have been introduced to address these issues,maximizing efficiency and achieving green-solvent processability and thermal stability for commercialization is necessary.Here,we synthesize a novel benzodifuran(BDF)-based HTM(asy-ranPBTBDF)showing an electron-deficient state,low steric hindrance,and low planarity compared to those of a typical benzodithiophene(BDT)-based HTM(asy-ranPBTBDT).BDF properties lead to deep high occupied molecular orbital(HOMO)levels,closeπ-πstacking,excellent solubility,and amorphous properties related to efficiency,green-solvent processability,and thermal stability.With these benefits,the asy-ranPBTBDF-based CQD-SC showed enhanced open-circuit voltage(Voc)(0.65 V)and PCE(13.29%)compared to those of the asy-ranPBTBDT-based device(0.63 V and 12.22%)in toxic processes with chlorobenzene.The asy-ranPBTBDF-based CQD-SC showed a PCE of 12.51%in a green-solvent process with 2-methylanisole and improved thermal stability at 80℃(83.8%retaining after 24 h)owing to less lateral crystallization than the asy-ranPBTBDT-based device(60.8%retaining after 24 h).展开更多
Passive daytime radiative cooling(PDRC) is environment-friendly without energy input by enhancing the coating's solar reflectance(R_(solar)) and thermal emittance(ε_(LWIR)) in the atmosphere's long-wave infra...Passive daytime radiative cooling(PDRC) is environment-friendly without energy input by enhancing the coating's solar reflectance(R_(solar)) and thermal emittance(ε_(LWIR)) in the atmosphere's long-wave infrared transmission window.However,high R_(solar) is usually achieved by increasing the coating's thickness,which not only increases materials' cost but also impairs heat transfer.Additionally,the desired high R_(solar) is vulnerable to dust pollution in the outdoors.In this work,a thin paint was designed by mixing hBN plates,PFOTS,and IPA. R_(solar)=0.963 and ε_(LWIR)=0.927 was achieved at a thickness of 150 μm due to the high backscattering ability of scatters.A high through-plane thermal conductivity(~1.82 W m^(-1) K^(-1)) also can be obtained.In addition,the porous structure coupled with the binder PFOTS resulted in a contact angle of 154°,demonstrating excellent durability under dust contamination.Outdoor experiments showed that the thin paint can obtain a 2.3℃ lower temperature for sub-ambient cooling than the reference PDRC coating in the daytime.Furtherly,the above-ambient heat dissipation performance can be enhanced by spraying the thin paint on a 3D heat sink,which was 15.7℃ lower than the reference 1D structure,demonstrating excellent performance for durable and scalable PDRC applications.展开更多
Featuring low cost, high abundance, low electrochemical potential, and large specific capacity, zinc(Zn)metal holds great potential as an anode material for next-generation rechargeable aqueous batteries.However, the ...Featuring low cost, high abundance, low electrochemical potential, and large specific capacity, zinc(Zn)metal holds great potential as an anode material for next-generation rechargeable aqueous batteries.However, the poor reversibility resulting from dendrite formation and side reactions poses a major obstacle for its practical application. Electrolyte, which is regarded as the “blood” of batteries, has a direct impact on reaction kinetics, mass transport, and side reactions and thus plays a key role in determining the electrochemical performance of Zn electrodes. Therefore, considerable efforts have been devoted to modulating the electrolytes to improve the performance of Zn electrodes. Although significant progress has been made, achieving stable and highly reversible Zn electrodes remains a critical challenge. This review aims to provide a systematic summary and discussion on electrolyte strategies for highperformance aqueous Zn batteries. The(electro)-chemical behavior and fundamental challenges of Zn electrodes in aqueous electrolytes are first discussed. Electrolyte modulation strategies developed to address these issues are then classified and elaborated according to the underlying mechanisms.Finally, remaining challenges and promising future research directions on aqueous electrolyte engineering are highlighted. This review offers insights into the design of highly efficient electrolytes for new generation of rechargeable Zn batteries.展开更多
The geometry of joints has a significant influence on the mechanical properties of rocks.To simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory e...The geometry of joints has a significant influence on the mechanical properties of rocks.To simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory experiments and numerical simulations.In this study,the computerized tomography (CT) scanning and photogrammetry were employed to obtain the internal and surface joint structures of a limestone sample,respectively.To describe the joint geometry,the edge detection algorithms and a three-dimensional (3D) matrix mapping method were applied to reconstruct CT-based and photogrammetry-based jointed rock models.For comparison tests,the numerical uniaxial compression tests were conducted on an intact rock sample and a sample with a joint simplified to a plane using the parallel computing method.The results indicate that the mechanical characteristics and failure process of jointed rocks are significantly affected by the geometry of joints.The presence of joints reduces the uniaxial compressive strength (UCS),elastic modulus,and released acoustic emission (AE) energy of rocks by 37%–67%,21%–24%,and 52%–90%,respectively.Compared to the simplified joint sample,the proposed photogrammetry-based numerical model makes the most of the limited geometry information of joints.The UCS,accumulative released AE energy,and elastic modulus of the photogrammetry-based sample were found to be very close to those of the CT-based sample.The UCS value of the simplified joint sample (i.e.38.5 MPa) is much lower than that of the CT-based sample (i.e.72.3 MPa).Additionally,the accumulative released AE energy observed in the simplified joint sample is 3.899 times lower than that observed in the CT-based sample.CT scanning provides a reliable means to visualize the joints in rocks,which can be used to verify the reliability of photogrammetry techniques.The application of the photogrammetry-based sample enables detailed analysis for estimating the mechanical properties of jointed rocks.展开更多
An unstably stratified flow entering into a stably stratified flow is referred to as penetrative convection,which is crucial to many physical processes and has been thought of as a key factor for extreme weather condi...An unstably stratified flow entering into a stably stratified flow is referred to as penetrative convection,which is crucial to many physical processes and has been thought of as a key factor for extreme weather conditions.Past theoretical,numerical,and experimental studies on penetrative convection are reviewed,along with field studies providing insights into turbulence modeling.The physical factors that initiate penetrative convection,including internal heat sources,nonlinear constitutive relationships,centrifugal forces and other complicated factors are summarized.Cutting-edge methods for understanding transport mechanisms and statistical properties of penetrative turbulence are also documented,e.g.,the variational approach and quasilinear approach,which derive scaling laws embedded in penetrative turbulence.Exploring these scaling laws in penetrative convection can improve our understanding of large-scale geophysical and astrophysical motions.To better the model of penetrative turbulence towards a practical situation,new directions,e.g.,penetrative convection in spheres,and radiation-forced convection,are proposed.展开更多
Solid-state supercapacitors(SSCs)are emerging as one of the promising energy storage devices due to their high safety,superior power density,and excellent cycling life.However,performance degradation and safety issues...Solid-state supercapacitors(SSCs)are emerging as one of the promising energy storage devices due to their high safety,superior power density,and excellent cycling life.However,performance degradation and safety issues under extreme conditions are the main challenges for the practical application.With the expansion of human activities,such as space missions,polar exploration,and so on,the investigation of SSC with wide temperature tolerance,high energy density,power density,and sustainability is highly desired.In this review,the effects of temperature on SSC are systematically illustrated and clarified,including the properties of the electrolyte,ion diffusion,and reaction dynamics of the supercapacitor.Subsequently,we summarize the recent advances in wide-temperature-range SSCs from the aspect of electrolyte modification,electrode design,and interface adjustment between electrode and electrolyte,especially with critical concerns on ionic conductivity and cycling stability.In the end,a perspective is presented,expecting to promote the practical application of the SSC in harsh conditions.展开更多
Compared with conventional solid-state electrolytes, halide solid-state electrolytes have several advantages such as a wider electrochemical window, better compatibility with oxide cathode materials, improved air stab...Compared with conventional solid-state electrolytes, halide solid-state electrolytes have several advantages such as a wider electrochemical window, better compatibility with oxide cathode materials, improved air stability,and easier preparation conditions making them conductive to industrial production. We concentrate on a typical halide solid-state electrolyte, Li_(3)InCl_(6), predict the most stable structure after doping with Br, F, and Ga by using the Alloy Theoretic Automated Toolkit based on first-principles calculations, and verify the accuracy of the prediction model. To investigate the potential of three equivalently doped ground state configurations of Li_(3)InCl_(6) as solid-state electrolytes for all-solid-state lithium-ion batteries, their specific properties such as crystal structure,band gap, convex packing energy, electrochemical stability window, and lithium-ion conductivity are computationally analyzed using first-principles calculations. After a comprehensive evaluation, it is determined that the F-doped ground state configuration Li_(3)InCl_(2.5)F_(3.5) exhibits better thermal stability, wider electrochemical stability window, and better lithium ion conductivity(1.80 m S·cm^(-1) at room temperature). Therefore, Li_(3)InCl_(2.5)F_(3.5) has the potential to be used in the field of all-solid-state lithium-ion batteries as a new type of halide electrolyte.展开更多
We study the nonlinear coupling of kinetic Alfvén waves with ion acoustic waves applicable to the Earth’s radiation belt and near-Sun streamer belt solar wind using dynamical equations in the form of modified Za...We study the nonlinear coupling of kinetic Alfvén waves with ion acoustic waves applicable to the Earth’s radiation belt and near-Sun streamer belt solar wind using dynamical equations in the form of modified Zakharov systems.Numerical simulations show the formation of magnetic field filamentary structures associated with density humps and dips which become turbulent at later times,redistributing the energy to higher wavenumbers.The magnetic power spectra exhibit an inertial range Kolmogorov-like spectral index value of-5/3 for k_(⊥)ρ_(i)<1 followed by a steeper dissipation range spectra with indices~-3 for the radiation belt case and~-4 for the nearSun streamer belt solar wind case,here k_(⊥)andρ_(i)represent the wavevector component perpendicular to the background magnetic field and the ion thermal gyroradius,respectively.Applying quasilinear theory in terms of the Fokker-Planck equation in the region of wavenumber turbulent spectra,we find the particle distribution function flattening in the superthermal tail population which is the signature of particle energization and plasma heating.展开更多
Coal mining-induced surface subsidence poses significant ecological and infrastructural challenges, necessitating a comprehensive study to ensure safe mining practices, particularly in underwater conditions. This proj...Coal mining-induced surface subsidence poses significant ecological and infrastructural challenges, necessitating a comprehensive study to ensure safe mining practices, particularly in underwater conditions. This project aims to address the extensive impact of coal mining on the environment, infrastructure, and overall safety, focusing on the Shigong River area above the working face. The study employs qualitative and quantitative analyses, along with on-site engineering measurements, to gather data on crucial parameters such as coal seam characteristics, roof rock lithology, thickness, water resistance, and structural damage degree. The research encompasses a multidisciplinary approach, involving mining, geology, hydrogeology, geophysical exploration, rock mechanics, mine surveying, and computational mathematics. The importance of effective safety measures and prevention techniques is emphasized, laying the foundation for research focused on the Xingyun coal mine. The brief concludes by highlighting the potential economic and social benefits of this project and its contribution to valuable experience for future subsea coal mining.展开更多
Biogasification of coal is important for clean utilization of coal. Experiments on the fermentation of single lignite, single straw and their mixture were performed to explore the variation characteristics of gas prod...Biogasification of coal is important for clean utilization of coal. Experiments on the fermentation of single lignite, single straw and their mixture were performed to explore the variation characteristics of gas production potential, microbial community and methanogenic metabolic pathways of mixture. Research has shown that mixed fermentation of lignite and straw significantly promoted biomethane production. The abundance of hydrolytic acidifying functional bacteria genera (Sphaerochaeta, Lentimicrobium) in mixed fermentation was higher than that in the fermentation of single lignite and single straw. The abundance of some key CAZy metabolic enzyme gene sequences in mixed fermentation group was increased, which was favorable to improve methane production. Aceticlastic methanogenesis was the most critical methanogenic pathway and acetic acid pathway was more competitive in methanogenic mode during peak fermentation. Macrogenomics provided theoretical support for the claim that mixed fermentation of coal and straw promoted biomethane metabolism, which was potentially valuable in expanding methanogenesis from mixed fermentation of lignite with different biomasses.展开更多
Taking the return air roadway of Tashan 8204 isolated island working face as the background, the evolution law of the stress field in the surrounding rock of the widened coal pillar area roadway during the mining peri...Taking the return air roadway of Tashan 8204 isolated island working face as the background, the evolution law of the stress field in the surrounding rock of the widened coal pillar area roadway during the mining period of the isolated island working face is obtained through numerical simulation. The hazardous area of strong mine pressure under different coal pillar widths is determined. Through simulation, it is known that when the width of the coal pillar is less than 20 m, there is large bearing capacity on the coal side of the roadway entity. The force on the side of the coal pillar is relatively small. When the width of the coal pillar ranges from 25 m to 45 m, the vertical stress on the roadway and surrounding areas is relatively high. Pressure relief measures need to be taken during mining to reduce surrounding rock stress. When the width of the coal pillar is greater than 45 m, the peak stress of the coal pillar is located in the deep part of the surrounding rock, but it still has a certain impact on the roadway. It is necessary to take pressure relief measures to transfer the stress to a deeper depth to ensure the stability of the triangular coal pillar during the safe mining period of the working face. This provides guidance for ensuring the stability of the triangular coal pillar during the safe mining period of the working face.展开更多
For the carbon-neutral,a multi-carrier renewable energy system(MRES),driven by the wind,solar and geothermal,was considered as an effective solution to mitigate CO2emissions and reduce energy usage in the building sec...For the carbon-neutral,a multi-carrier renewable energy system(MRES),driven by the wind,solar and geothermal,was considered as an effective solution to mitigate CO2emissions and reduce energy usage in the building sector.A proper sizing method was essential for achieving the desired 100%renewable energy system of resources.This paper presented a bi-objective optimization formulation for sizing the MRES using a constrained genetic algorithm(GA)coupled with the loss of power supply probability(LPSP)method to achieve the minimal cost of the system and the reliability of the system to the load real time requirement.An optimization App has been developed in MATLAB environment to offer a user-friendly interface and output the optimized design parameters when given the load demand.A case study of a swimming pool building was used to demonstrate the process of the proposed design method.Compared to the conventional distributed energy system,the MRES is feasible with a lower annual total cost(ATC).Additionally,the ATC decreases as the power supply reliability of the renewable system decreases.There is a decrease of 24%of the annual total cost when the power supply probability is equal to 8%compared to the baseline case with 0%power supply probability.展开更多
The effects of saturation on post-peak mechanical properties and energy features are main focal points for sandstones. To obtain these important attributes, post-peak cyclic loading and unloading tests were conducted ...The effects of saturation on post-peak mechanical properties and energy features are main focal points for sandstones. To obtain these important attributes, post-peak cyclic loading and unloading tests were conducted on sandstone rock samples under natural and saturated states using the RMT-150B rock mechanics testing system. After successful processing of these tests, comparisons of stress-strain, strength, deformation, damage, and degradation of mechanical properties, wave velocity, and energy features of sandstone were conducted between natural and saturated states. The results show that saturation has evident weakening effects on uniaxial cyclic loading and unloading strength and elastic modulus of post-peak fracture sandstone. With the increase of post-peak loading and unloading period, the increases in amplitude of peak axial, lateral, and volumetric strains are all enhanced at approximately constant speed under the natural state. The increase in amplitude of axial peak strain is also enhanced at approximately constant speed, while the amplitudes of lateral and volumetric peak strains increase significantly under the saturated state. Compared with the natural state, the increase in amplitude of saturated samples' peak lateral and volumetric strains, and the post-peak cyclic loading and unloading period all conform to the linearly increasing relationship. Under natural and saturated states, the damage factor (the plastic shear strain) of each rock sample gradually increases with the increase of post-peak cyclic loading and unloading period, and the crack damage stress of each rock sample declines rapidly at first and tends to reach a constant value later with the increase in plastic shear strain. Under natural and saturated states, the wave velocities of rock samples all decrease in the process of post-peak cyclic loading and unloading with the increase in plastic shear strain. The wave velocities of rock samples and plastic shear strain conform to the exponential relationship with a constant. Saturation reduces the total absorption energy, dissipated energy, and elastic strain energy of rock samples.展开更多
An accurate long-term energy demand forecasting is essential for energy planning and policy making. However, due to the immature energy data collecting and statistical methods, the available data are usually limited i...An accurate long-term energy demand forecasting is essential for energy planning and policy making. However, due to the immature energy data collecting and statistical methods, the available data are usually limited in many regions. In this paper, on the basis of comprehensive literature review, we proposed a hybrid model based on the long-range alternative energy planning (LEAP) model to improve the accuracy of energy demand forecasting in these regions. By taking Hunan province, China as a typical case, the proposed hybrid model was applied to estimating the possible future energy demand and energy-saving potentials in different sectors. The structure of LEAP model was estimated by Sankey energy flow, and Leslie matrix and autoregressive integrated moving average (ARIMA) models were used to predict the population, industrial structure and transportation turnover, respectively. Monte-Carlo method was employed to evaluate the uncertainty of forecasted results. The results showed that the hybrid model combined with scenario analysis provided a relatively accurate forecast for the long-term energy demand in regions with limited statistical data, and the average standard error of probabilistic distribution in 2030 energy demand was as low as 0.15. The prediction results could provide supportive references to identify energy-saving potentials and energy development pathways.展开更多
For acquiring the details in aluminum holding furnace with bottom porous brick purging system,efforts were performed to try to find out the potential optimal operation schemes.By adopting transient analysis scheme and...For acquiring the details in aluminum holding furnace with bottom porous brick purging system,efforts were performed to try to find out the potential optimal operation schemes.By adopting transient analysis scheme and constant boundary temperature,combustion in the furnace was investigated numerically using computational fluid dynamics(CFD).The predicted gas temperature shows good agreement with the measured results,and the predicted energy distribution of the furnace is consistent with that obtained from energy balance experiment,which confirms the reliability of the numerical solution.The results show that as the fuel-air mixture temperature rises up from 300 K to 500 K,the energy utilization of the furnace could increase from 34.55% to 37.14%.However,as the excess air coefficient increases from 1.0 to 1.4,energy utilization drops from 34.55% to 29.56%.Increasing the combustion temperature is the most effective way to improve the energy efficiency of the furnace.High reactant temperature and medium excess air coefficient are recommended for high operation performance,and keeping the furnace jamb sealed well for avoiding leakage has to be emphasized.展开更多
High-energy–density lithium-ion batteries(LIBs)that can be safely fast-charged are desirable for electric vehicles.However,sub-optimal lithiation potential and low capacity of commonly used LIBs anode cause safety is...High-energy–density lithium-ion batteries(LIBs)that can be safely fast-charged are desirable for electric vehicles.However,sub-optimal lithiation potential and low capacity of commonly used LIBs anode cause safety issues and low energy density.Here we hypothesize that a cobalt vanadate oxide,Co_(2)VO_(4),can be attractive anode material for fast-charging LIBs due to its high capacity(~1000 mAh g^(−1))and safe lithiation potential(~0.65 V vs.Li^(+)/Li).The Li+diffusion coefficient of Co2VO4 is evaluated by theoretical calculation to be as high as 3.15×10^(-10) cm^(2) s^(−1),proving Co_(2)VO_(4) a promising anode in fast-charging LIBs.A hexagonal porous Co2VO4 nanodisk(PCVO ND)structure is designed accordingly,featuring a high specific surface area of 74.57 m^(2) g^(−1) and numerous pores with a pore size of 14 nm.This unique structure succeeds in enhancing Li^(+) and electron transfer,leading to superior fast-charging performance than current commercial anodes.As a result,the PCVO ND shows a high initial reversible capacity of 911.0 mAh g^(−1) at 0.4 C,excellent fast-charging capacity(344.3 mAh g^(−1) at 10 C for 1000 cycles),outstanding long-term cycling stability(only 0.024% capacity loss per cycle at 10 C for 1000 cycles),confirming the commercial feasibility of PCVO ND in fast-charging LIBs.展开更多
Borehole leakage not only affects the gas drainage effect but also presents considerable risk to human security. For the research on the leakage mechanism of gas drainage borehole, the rheological and visco-elastic-pl...Borehole leakage not only affects the gas drainage effect but also presents considerable risk to human security. For the research on the leakage mechanism of gas drainage borehole, the rheological and visco-elastic-plastic characteristics were considered to establish the mechanical model of coal mass around borehole, which is used to analyze the leakage mechanism and deduce the dynamic leakage model. On the basis of the real coal seam conditions, the variation rules of the stress, leakage ring, and air leakage amount were analyzed through numerical simulation, and the influence factors of air leakage amount were also investigated to provide the theoretical basis for the sealing technology. Results show that the air leakage amount of borehole is inversely proportional to the increase in supporting stress and sealing length, and directly correlated with the increase in borehole radius and softening modulus. Using theoretical analysis, we design a novel active supporting sealing technology that can use grouting material to seal the fractures to reduce the leakage channels and also provide supporting stress to prevent borehole deformation. The engineering test results indicate that the average gas concentration with the novel active supporting sealing technology is increased by 162.12% than that of traditional polyurethane sealing method. Therefore, this technology not only effectively resolves borehole leakage but also significantly improves the gas drainage effect.展开更多
As the biggest agricultural country, China has an abundant rice straw energy resource. The characteristics of typical china rice straws are presented as high moisture contents, high volatile contents, high ash content...As the biggest agricultural country, China has an abundant rice straw energy resource. The characteristics of typical china rice straws are presented as high moisture contents, high volatile contents, high ash contents and low bulk density. At present, rice straw is mainly used as fuel, feedstuff, fertilizer and industrial raw material. With improved living conditions in rural areas, farmers tend to rely more on commercial fuel, which leads to even more open field burning of rice straw, and brings air pollutions and potential energy waste as well. The Chinese government is studying relevant policies on acceleration of comprehensive utilization of rice straw with the goal of utilization rate exceeding 80% in 2015. In this paper, focus is on the combustion of rice straw to extract energy, and related challenges face to china is put forward in this paper also.展开更多
文摘It is regretful that the Acknowledgments part was lost in the final process of publication.The Acknowledgments part should be added as follow.The work described in this paper was supported by the grants from the Research Grants Council of the Hong Kong Special Administrative Region,China(Project No.16205721).
文摘Chemical leaching of coals would be required to produce cleaner coals for some special applications where physical benefi-ciation may not be effective enough.This would also help in recovering Li and rare earth metals besides in the sequestration of CO_(2).About 20 Indian coals having complexly distributed moderate to high ash contents were sequentially treated with various alkali–acid such as NaOH-HCl,HF,HCl,HCl-HF,and NaOH-HCl-HF leaching.This aimed to establish and design the best stepwise sequential process for the highest degree of demineralisation through a chemical leaching process.Kinetics and process intensification studies were carried out.More than 80%demineralisation of Madhaipur and Neemcha coals was observed using the best sequential treatment designed presently.The repeated stepwise treatment of the alkali and the acid was also studied,which was found to significantly enhance the degree of demineralisation of coals.The integrated process of alkali–acid leaching followed by solvent extraction(Organo-refining)and vice versa of the treated coal was also studied for producing cleaner coals.
基金supported by National Research Foundation of Korea(NRF)grant funded by Ministry of Science and ICT(MSIT)(2021R1A2C3004420,2021M3H4A1A02055684,and 2020R1C1C1012256)the DGIST R&D Program of the Ministry of Science and ICT(21-CoE-ET-01)Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(2021R1A6A3A14038599).
文摘For efficient colloidal quantum dot(CQD)solar cells(CQD-SCs),thiol-passivated p-type CQDs are generally used as a hole-transporting material(HTM);however,there are issues with the control of optoelectrical properties,low thiol passivation rate,and poor morphology with a power conversion efficiency(PCE)of approximately 11%.Although polymeric HTMs have been introduced to address these issues,maximizing efficiency and achieving green-solvent processability and thermal stability for commercialization is necessary.Here,we synthesize a novel benzodifuran(BDF)-based HTM(asy-ranPBTBDF)showing an electron-deficient state,low steric hindrance,and low planarity compared to those of a typical benzodithiophene(BDT)-based HTM(asy-ranPBTBDT).BDF properties lead to deep high occupied molecular orbital(HOMO)levels,closeπ-πstacking,excellent solubility,and amorphous properties related to efficiency,green-solvent processability,and thermal stability.With these benefits,the asy-ranPBTBDF-based CQD-SC showed enhanced open-circuit voltage(Voc)(0.65 V)and PCE(13.29%)compared to those of the asy-ranPBTBDT-based device(0.63 V and 12.22%)in toxic processes with chlorobenzene.The asy-ranPBTBDF-based CQD-SC showed a PCE of 12.51%in a green-solvent process with 2-methylanisole and improved thermal stability at 80℃(83.8%retaining after 24 h)owing to less lateral crystallization than the asy-ranPBTBDT-based device(60.8%retaining after 24 h).
基金financially supported by the Natural Science Foundation of Hunan Province(Grant No.2021JJ40732)the Central South University Innovation-Driven Research Programme(Grant No.2023CXQD012)。
文摘Passive daytime radiative cooling(PDRC) is environment-friendly without energy input by enhancing the coating's solar reflectance(R_(solar)) and thermal emittance(ε_(LWIR)) in the atmosphere's long-wave infrared transmission window.However,high R_(solar) is usually achieved by increasing the coating's thickness,which not only increases materials' cost but also impairs heat transfer.Additionally,the desired high R_(solar) is vulnerable to dust pollution in the outdoors.In this work,a thin paint was designed by mixing hBN plates,PFOTS,and IPA. R_(solar)=0.963 and ε_(LWIR)=0.927 was achieved at a thickness of 150 μm due to the high backscattering ability of scatters.A high through-plane thermal conductivity(~1.82 W m^(-1) K^(-1)) also can be obtained.In addition,the porous structure coupled with the binder PFOTS resulted in a contact angle of 154°,demonstrating excellent durability under dust contamination.Outdoor experiments showed that the thin paint can obtain a 2.3℃ lower temperature for sub-ambient cooling than the reference PDRC coating in the daytime.Furtherly,the above-ambient heat dissipation performance can be enhanced by spraying the thin paint on a 3D heat sink,which was 15.7℃ lower than the reference 1D structure,demonstrating excellent performance for durable and scalable PDRC applications.
文摘Featuring low cost, high abundance, low electrochemical potential, and large specific capacity, zinc(Zn)metal holds great potential as an anode material for next-generation rechargeable aqueous batteries.However, the poor reversibility resulting from dendrite formation and side reactions poses a major obstacle for its practical application. Electrolyte, which is regarded as the “blood” of batteries, has a direct impact on reaction kinetics, mass transport, and side reactions and thus plays a key role in determining the electrochemical performance of Zn electrodes. Therefore, considerable efforts have been devoted to modulating the electrolytes to improve the performance of Zn electrodes. Although significant progress has been made, achieving stable and highly reversible Zn electrodes remains a critical challenge. This review aims to provide a systematic summary and discussion on electrolyte strategies for highperformance aqueous Zn batteries. The(electro)-chemical behavior and fundamental challenges of Zn electrodes in aqueous electrolytes are first discussed. Electrolyte modulation strategies developed to address these issues are then classified and elaborated according to the underlying mechanisms.Finally, remaining challenges and promising future research directions on aqueous electrolyte engineering are highlighted. This review offers insights into the design of highly efficient electrolytes for new generation of rechargeable Zn batteries.
基金supported by the National Natural Science Foundation of China(Grant Nos.42277150,41977219)Henan Provincial Science and Technology Research Project(Grant No.222102320271).
文摘The geometry of joints has a significant influence on the mechanical properties of rocks.To simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory experiments and numerical simulations.In this study,the computerized tomography (CT) scanning and photogrammetry were employed to obtain the internal and surface joint structures of a limestone sample,respectively.To describe the joint geometry,the edge detection algorithms and a three-dimensional (3D) matrix mapping method were applied to reconstruct CT-based and photogrammetry-based jointed rock models.For comparison tests,the numerical uniaxial compression tests were conducted on an intact rock sample and a sample with a joint simplified to a plane using the parallel computing method.The results indicate that the mechanical characteristics and failure process of jointed rocks are significantly affected by the geometry of joints.The presence of joints reduces the uniaxial compressive strength (UCS),elastic modulus,and released acoustic emission (AE) energy of rocks by 37%–67%,21%–24%,and 52%–90%,respectively.Compared to the simplified joint sample,the proposed photogrammetry-based numerical model makes the most of the limited geometry information of joints.The UCS,accumulative released AE energy,and elastic modulus of the photogrammetry-based sample were found to be very close to those of the CT-based sample.The UCS value of the simplified joint sample (i.e.38.5 MPa) is much lower than that of the CT-based sample (i.e.72.3 MPa).Additionally,the accumulative released AE energy observed in the simplified joint sample is 3.899 times lower than that observed in the CT-based sample.CT scanning provides a reliable means to visualize the joints in rocks,which can be used to verify the reliability of photogrammetry techniques.The application of the photogrammetry-based sample enables detailed analysis for estimating the mechanical properties of jointed rocks.
基金supported by the Heilongjiang Touyan Innovative Program Teammade possible through the generous support of the NSFC (Grant No. 52176065)the Fundamental Research Funds for the Central Universities(Grant No. 2022FRFK060022)
文摘An unstably stratified flow entering into a stably stratified flow is referred to as penetrative convection,which is crucial to many physical processes and has been thought of as a key factor for extreme weather conditions.Past theoretical,numerical,and experimental studies on penetrative convection are reviewed,along with field studies providing insights into turbulence modeling.The physical factors that initiate penetrative convection,including internal heat sources,nonlinear constitutive relationships,centrifugal forces and other complicated factors are summarized.Cutting-edge methods for understanding transport mechanisms and statistical properties of penetrative turbulence are also documented,e.g.,the variational approach and quasilinear approach,which derive scaling laws embedded in penetrative turbulence.Exploring these scaling laws in penetrative convection can improve our understanding of large-scale geophysical and astrophysical motions.To better the model of penetrative turbulence towards a practical situation,new directions,e.g.,penetrative convection in spheres,and radiation-forced convection,are proposed.
基金Special Fund for Carbon Peak and Carbon Neutralization Scientific and Technological Innovation Project of Jiangsu Province,Grant/Award Number:BE2022042National Natural Science Foundation of China,Grant/Award Numbers:22201275,51873086,51673096,51873086,51673096+2 种基金the Project on the Enterprises-Universities-Research Cooperation of Kucap Smart Technology(Nanjing)Co.,Ltd.,Grant/Award Number:202240607Postgraduate Research&Practice Innovation Program of Jiangsu Province,Grant/Award Number:KYCX23-1407Anhui Provincial Natural Science Foundation,Grant/Award Number:2208085QB32。
文摘Solid-state supercapacitors(SSCs)are emerging as one of the promising energy storage devices due to their high safety,superior power density,and excellent cycling life.However,performance degradation and safety issues under extreme conditions are the main challenges for the practical application.With the expansion of human activities,such as space missions,polar exploration,and so on,the investigation of SSC with wide temperature tolerance,high energy density,power density,and sustainability is highly desired.In this review,the effects of temperature on SSC are systematically illustrated and clarified,including the properties of the electrolyte,ion diffusion,and reaction dynamics of the supercapacitor.Subsequently,we summarize the recent advances in wide-temperature-range SSCs from the aspect of electrolyte modification,electrode design,and interface adjustment between electrode and electrolyte,especially with critical concerns on ionic conductivity and cycling stability.In the end,a perspective is presented,expecting to promote the practical application of the SSC in harsh conditions.
基金supported by the National Key Research and Development Program of China (Grant No. 2021YFF0500600)。
文摘Compared with conventional solid-state electrolytes, halide solid-state electrolytes have several advantages such as a wider electrochemical window, better compatibility with oxide cathode materials, improved air stability,and easier preparation conditions making them conductive to industrial production. We concentrate on a typical halide solid-state electrolyte, Li_(3)InCl_(6), predict the most stable structure after doping with Br, F, and Ga by using the Alloy Theoretic Automated Toolkit based on first-principles calculations, and verify the accuracy of the prediction model. To investigate the potential of three equivalently doped ground state configurations of Li_(3)InCl_(6) as solid-state electrolytes for all-solid-state lithium-ion batteries, their specific properties such as crystal structure,band gap, convex packing energy, electrochemical stability window, and lithium-ion conductivity are computationally analyzed using first-principles calculations. After a comprehensive evaluation, it is determined that the F-doped ground state configuration Li_(3)InCl_(2.5)F_(3.5) exhibits better thermal stability, wider electrochemical stability window, and better lithium ion conductivity(1.80 m S·cm^(-1) at room temperature). Therefore, Li_(3)InCl_(2.5)F_(3.5) has the potential to be used in the field of all-solid-state lithium-ion batteries as a new type of halide electrolyte.
基金the University Grants Commission,India for providing a Non-NET fellowship。
文摘We study the nonlinear coupling of kinetic Alfvén waves with ion acoustic waves applicable to the Earth’s radiation belt and near-Sun streamer belt solar wind using dynamical equations in the form of modified Zakharov systems.Numerical simulations show the formation of magnetic field filamentary structures associated with density humps and dips which become turbulent at later times,redistributing the energy to higher wavenumbers.The magnetic power spectra exhibit an inertial range Kolmogorov-like spectral index value of-5/3 for k_(⊥)ρ_(i)<1 followed by a steeper dissipation range spectra with indices~-3 for the radiation belt case and~-4 for the nearSun streamer belt solar wind case,here k_(⊥)andρ_(i)represent the wavevector component perpendicular to the background magnetic field and the ion thermal gyroradius,respectively.Applying quasilinear theory in terms of the Fokker-Planck equation in the region of wavenumber turbulent spectra,we find the particle distribution function flattening in the superthermal tail population which is the signature of particle energization and plasma heating.
文摘Coal mining-induced surface subsidence poses significant ecological and infrastructural challenges, necessitating a comprehensive study to ensure safe mining practices, particularly in underwater conditions. This project aims to address the extensive impact of coal mining on the environment, infrastructure, and overall safety, focusing on the Shigong River area above the working face. The study employs qualitative and quantitative analyses, along with on-site engineering measurements, to gather data on crucial parameters such as coal seam characteristics, roof rock lithology, thickness, water resistance, and structural damage degree. The research encompasses a multidisciplinary approach, involving mining, geology, hydrogeology, geophysical exploration, rock mechanics, mine surveying, and computational mathematics. The importance of effective safety measures and prevention techniques is emphasized, laying the foundation for research focused on the Xingyun coal mine. The brief concludes by highlighting the potential economic and social benefits of this project and its contribution to valuable experience for future subsea coal mining.
文摘Biogasification of coal is important for clean utilization of coal. Experiments on the fermentation of single lignite, single straw and their mixture were performed to explore the variation characteristics of gas production potential, microbial community and methanogenic metabolic pathways of mixture. Research has shown that mixed fermentation of lignite and straw significantly promoted biomethane production. The abundance of hydrolytic acidifying functional bacteria genera (Sphaerochaeta, Lentimicrobium) in mixed fermentation was higher than that in the fermentation of single lignite and single straw. The abundance of some key CAZy metabolic enzyme gene sequences in mixed fermentation group was increased, which was favorable to improve methane production. Aceticlastic methanogenesis was the most critical methanogenic pathway and acetic acid pathway was more competitive in methanogenic mode during peak fermentation. Macrogenomics provided theoretical support for the claim that mixed fermentation of coal and straw promoted biomethane metabolism, which was potentially valuable in expanding methanogenesis from mixed fermentation of lignite with different biomasses.
文摘Taking the return air roadway of Tashan 8204 isolated island working face as the background, the evolution law of the stress field in the surrounding rock of the widened coal pillar area roadway during the mining period of the isolated island working face is obtained through numerical simulation. The hazardous area of strong mine pressure under different coal pillar widths is determined. Through simulation, it is known that when the width of the coal pillar is less than 20 m, there is large bearing capacity on the coal side of the roadway entity. The force on the side of the coal pillar is relatively small. When the width of the coal pillar ranges from 25 m to 45 m, the vertical stress on the roadway and surrounding areas is relatively high. Pressure relief measures need to be taken during mining to reduce surrounding rock stress. When the width of the coal pillar is greater than 45 m, the peak stress of the coal pillar is located in the deep part of the surrounding rock, but it still has a certain impact on the roadway. It is necessary to take pressure relief measures to transfer the stress to a deeper depth to ensure the stability of the triangular coal pillar during the safe mining period of the working face. This provides guidance for ensuring the stability of the triangular coal pillar during the safe mining period of the working face.
基金Project(52108101)supported by the National Natural Science Foundation of ChinaProjects(2020GK4057,2021JJ40759)supported by the Hunan Provincial Science and Technology Department,China。
文摘For the carbon-neutral,a multi-carrier renewable energy system(MRES),driven by the wind,solar and geothermal,was considered as an effective solution to mitigate CO2emissions and reduce energy usage in the building sector.A proper sizing method was essential for achieving the desired 100%renewable energy system of resources.This paper presented a bi-objective optimization formulation for sizing the MRES using a constrained genetic algorithm(GA)coupled with the loss of power supply probability(LPSP)method to achieve the minimal cost of the system and the reliability of the system to the load real time requirement.An optimization App has been developed in MATLAB environment to offer a user-friendly interface and output the optimized design parameters when given the load demand.A case study of a swimming pool building was used to demonstrate the process of the proposed design method.Compared to the conventional distributed energy system,the MRES is feasible with a lower annual total cost(ATC).Additionally,the ATC decreases as the power supply reliability of the renewable system decreases.There is a decrease of 24%of the annual total cost when the power supply probability is equal to 8%compared to the baseline case with 0%power supply probability.
基金Projects(51304068, 51674101, 51374112) supported by the National Natural Science Foundation of China Project(17FTUE03) supported by the Fujian Research Center for Tunneling and Urban Underground Space Engineering (Huaqiao University), China Project(2018M632574) supported by the Postdoctoral Science Foundation of China
文摘The effects of saturation on post-peak mechanical properties and energy features are main focal points for sandstones. To obtain these important attributes, post-peak cyclic loading and unloading tests were conducted on sandstone rock samples under natural and saturated states using the RMT-150B rock mechanics testing system. After successful processing of these tests, comparisons of stress-strain, strength, deformation, damage, and degradation of mechanical properties, wave velocity, and energy features of sandstone were conducted between natural and saturated states. The results show that saturation has evident weakening effects on uniaxial cyclic loading and unloading strength and elastic modulus of post-peak fracture sandstone. With the increase of post-peak loading and unloading period, the increases in amplitude of peak axial, lateral, and volumetric strains are all enhanced at approximately constant speed under the natural state. The increase in amplitude of axial peak strain is also enhanced at approximately constant speed, while the amplitudes of lateral and volumetric peak strains increase significantly under the saturated state. Compared with the natural state, the increase in amplitude of saturated samples' peak lateral and volumetric strains, and the post-peak cyclic loading and unloading period all conform to the linearly increasing relationship. Under natural and saturated states, the damage factor (the plastic shear strain) of each rock sample gradually increases with the increase of post-peak cyclic loading and unloading period, and the crack damage stress of each rock sample declines rapidly at first and tends to reach a constant value later with the increase in plastic shear strain. Under natural and saturated states, the wave velocities of rock samples all decrease in the process of post-peak cyclic loading and unloading with the increase in plastic shear strain. The wave velocities of rock samples and plastic shear strain conform to the exponential relationship with a constant. Saturation reduces the total absorption energy, dissipated energy, and elastic strain energy of rock samples.
基金Project(51606225) supported by the National Natural Science Foundation of ChinaProject(2016JJ2144) supported by Hunan Provincial Natural Science Foundation of ChinaProject(502221703) supported by Graduate Independent Explorative Innovation Foundation of Central South University,China
文摘An accurate long-term energy demand forecasting is essential for energy planning and policy making. However, due to the immature energy data collecting and statistical methods, the available data are usually limited in many regions. In this paper, on the basis of comprehensive literature review, we proposed a hybrid model based on the long-range alternative energy planning (LEAP) model to improve the accuracy of energy demand forecasting in these regions. By taking Hunan province, China as a typical case, the proposed hybrid model was applied to estimating the possible future energy demand and energy-saving potentials in different sectors. The structure of LEAP model was estimated by Sankey energy flow, and Leslie matrix and autoregressive integrated moving average (ARIMA) models were used to predict the population, industrial structure and transportation turnover, respectively. Monte-Carlo method was employed to evaluate the uncertainty of forecasted results. The results showed that the hybrid model combined with scenario analysis provided a relatively accurate forecast for the long-term energy demand in regions with limited statistical data, and the average standard error of probabilistic distribution in 2030 energy demand was as low as 0.15. The prediction results could provide supportive references to identify energy-saving potentials and energy development pathways.
基金Project(2009GK2009) supported by the Science and Technology Program of Hunan Province,China
文摘For acquiring the details in aluminum holding furnace with bottom porous brick purging system,efforts were performed to try to find out the potential optimal operation schemes.By adopting transient analysis scheme and constant boundary temperature,combustion in the furnace was investigated numerically using computational fluid dynamics(CFD).The predicted gas temperature shows good agreement with the measured results,and the predicted energy distribution of the furnace is consistent with that obtained from energy balance experiment,which confirms the reliability of the numerical solution.The results show that as the fuel-air mixture temperature rises up from 300 K to 500 K,the energy utilization of the furnace could increase from 34.55% to 37.14%.However,as the excess air coefficient increases from 1.0 to 1.4,energy utilization drops from 34.55% to 29.56%.Increasing the combustion temperature is the most effective way to improve the energy efficiency of the furnace.High reactant temperature and medium excess air coefficient are recommended for high operation performance,and keeping the furnace jamb sealed well for avoiding leakage has to be emphasized.
基金supported by the National Key Research and Development Project(2018YFE0124800)the National Nature Science Foundation of China(51702157,51873086,51673096).
文摘High-energy–density lithium-ion batteries(LIBs)that can be safely fast-charged are desirable for electric vehicles.However,sub-optimal lithiation potential and low capacity of commonly used LIBs anode cause safety issues and low energy density.Here we hypothesize that a cobalt vanadate oxide,Co_(2)VO_(4),can be attractive anode material for fast-charging LIBs due to its high capacity(~1000 mAh g^(−1))and safe lithiation potential(~0.65 V vs.Li^(+)/Li).The Li+diffusion coefficient of Co2VO4 is evaluated by theoretical calculation to be as high as 3.15×10^(-10) cm^(2) s^(−1),proving Co_(2)VO_(4) a promising anode in fast-charging LIBs.A hexagonal porous Co2VO4 nanodisk(PCVO ND)structure is designed accordingly,featuring a high specific surface area of 74.57 m^(2) g^(−1) and numerous pores with a pore size of 14 nm.This unique structure succeeds in enhancing Li^(+) and electron transfer,leading to superior fast-charging performance than current commercial anodes.As a result,the PCVO ND shows a high initial reversible capacity of 911.0 mAh g^(−1) at 0.4 C,excellent fast-charging capacity(344.3 mAh g^(−1) at 10 C for 1000 cycles),outstanding long-term cycling stability(only 0.024% capacity loss per cycle at 10 C for 1000 cycles),confirming the commercial feasibility of PCVO ND in fast-charging LIBs.
基金supported by the National Natural Science Foundation of Youth Science Fund Project of China (No. 51604096)Funded by Hebei State Key Laboratory of Mine Disaster Prevention of China (No. KJZH2017K08)+1 种基金Funded by the Research Fund of State and Local Joint Engineering Laboratory for Gas Drainage & Ground Control of Deep Mines (Henan Polytechnic University) of China (No. G201609)He Nan Research Program of Application Foundation and Advanced Technology of China (No. 162300410031)
文摘Borehole leakage not only affects the gas drainage effect but also presents considerable risk to human security. For the research on the leakage mechanism of gas drainage borehole, the rheological and visco-elastic-plastic characteristics were considered to establish the mechanical model of coal mass around borehole, which is used to analyze the leakage mechanism and deduce the dynamic leakage model. On the basis of the real coal seam conditions, the variation rules of the stress, leakage ring, and air leakage amount were analyzed through numerical simulation, and the influence factors of air leakage amount were also investigated to provide the theoretical basis for the sealing technology. Results show that the air leakage amount of borehole is inversely proportional to the increase in supporting stress and sealing length, and directly correlated with the increase in borehole radius and softening modulus. Using theoretical analysis, we design a novel active supporting sealing technology that can use grouting material to seal the fractures to reduce the leakage channels and also provide supporting stress to prevent borehole deformation. The engineering test results indicate that the average gas concentration with the novel active supporting sealing technology is increased by 162.12% than that of traditional polyurethane sealing method. Therefore, this technology not only effectively resolves borehole leakage but also significantly improves the gas drainage effect.
文摘As the biggest agricultural country, China has an abundant rice straw energy resource. The characteristics of typical china rice straws are presented as high moisture contents, high volatile contents, high ash contents and low bulk density. At present, rice straw is mainly used as fuel, feedstuff, fertilizer and industrial raw material. With improved living conditions in rural areas, farmers tend to rely more on commercial fuel, which leads to even more open field burning of rice straw, and brings air pollutions and potential energy waste as well. The Chinese government is studying relevant policies on acceleration of comprehensive utilization of rice straw with the goal of utilization rate exceeding 80% in 2015. In this paper, focus is on the combustion of rice straw to extract energy, and related challenges face to china is put forward in this paper also.