Ellagic acid(EA)is a natural antioxidant,widely present in a lot of forms’soft fruits,nuts,and other plant tissues,and helpful for promoting human health;however,its protective effect on postharvest fruit and improvi...Ellagic acid(EA)is a natural antioxidant,widely present in a lot of forms’soft fruits,nuts,and other plant tissues,and helpful for promoting human health;however,its protective effect on postharvest fruit and improving the quality index of postharvest fruit have rarely been studied.In this experiment,the strawberries were soaked in 0,100,200,300,400,and 500 mg L^(−1) EA,respectively,and the influential EA on fruit quality and the antioxidant system of strawberries were studied.Compared with the control,EA treatment can reduce the browning degree and rotting rate of strawberry fruit during storage and augment the soluble solid content(SSC).EA treatment can also increase the content of related stuff and enzyme activity in antioxidant systems;the gene expression level of polyphenol oxidase(PPO)in strawberries treated with EA was always down-regulated,correspondingly,the expression of other antioxidant enzyme genes was enhanced.Among the strawberry fruits treated with EA of different concentrations,300 mg L^(−1) EA had the best effect in the process of strawberry preservation.The results suggested that the proper concentration of exogenous EA at 300 mg L−1 could maintain strawberries’quality and enhance the antioxidant system by improving the activities of antioxidative enzymes and the ascorbateglutathione(AsA-GSH)cycle during storage.展开更多
Underground pumped storage power plant(UPSP)is an innovative concept for space recycling of abandoned mines.Its realization requires better understanding of the dynamic performance and durability of reservoir rock.Thi...Underground pumped storage power plant(UPSP)is an innovative concept for space recycling of abandoned mines.Its realization requires better understanding of the dynamic performance and durability of reservoir rock.This paper conducted ultrasonic detection,split Hopkinson pressure bar(SHPB)impact,mercury intrusion porosimetry(MIP),and backscatter electron observation(BSE)tests to investigate the dynamical behaviour and microstructure of sandstone with cyclical dry-wet damage.A coupling FEM-DEM model was constructed for reappearing mesoscopic structure damage.The results show that dry-wet cycles decrease the dynamic compressive strength(DCS)with a maximum reduction of 39.40%,the elastic limit strength is reduced from 41.75 to 25.62 MPa.The sieved fragments obtain the highest crack growth rate during the 23rd dry-wet cycle with a predictable life of 25 cycles for each rock particle.The pore fractal features of the macropores and micro-meso pores show great differences between the early and late cycles,which verifies the computational statistics analysis of particle deterioration.The numerical results show that the failure patterns are governed by the strain in pre-peak stage and the shear cracks are dominant.The dry-wet cycles reduce the energy transfer efficiency and lead to the discretization of force chain and crack fields.展开更多
The concept of the carbon cycle in the old goaf of a coal mine based on CO_(2)utilization and storage was put forward adhering to the principle of low-carbon development,utilization of space resources in old goafs,and...The concept of the carbon cycle in the old goaf of a coal mine based on CO_(2)utilization and storage was put forward adhering to the principle of low-carbon development,utilization of space resources in old goafs,and associated gas resources development.Firstly,the evolution characteristics of overburden fissures in the goaf of the case was studied using a two-dimensional physical similarity simulation test,the sealing performance of the caprocks after stabilization was analyzed,and the fissures were counted and classi-fied.Then,the process of gaseous CO_(2)injection in the connected fissure was simulated by Ansys Fluent software,and the migration law and distribution characteristics of CO_(2)under the condition of gaseous CO_(2)injection were analyzed.Finally,the estimation models of free CO_(2)storage capacity in the old goaf were constructed considering the proportion of connected fissure and the effectiveness of CO_(2)injection.The CO_(2)storage capacity in the old goaf of the case coal mine was estimated.The results showed that a caprock group of“hard-thickness low-permeability hard-thickness”was formed after the caprock-fissures system in the goaf of the case tended to be stable vertically.The connected fissure,occlude cracks,and micro-fractures in the goaf accounted for 85.5%,8.5%,and 6%of the total fissures,respectively.Gaseous CO_(2)first migrated to the bottom of the connected fissure after CO_(2)was injected into the goaf,then spread horizontally along the bottom of the connected fissure after reaching the bottom,and finally spread longitudinally after filling the bottom of the entire connected fissure.The theoretical and effective storage capacities of free CO_(2)at normal temperature and pressure in the old goaf of the case were 9757 and 7477 t,respectively.The effective storage capacity of free CO_(2)at normal temperature and pressure in the old goaf after all minefield mined was 193404 t.The research can provide some reference for the coal mining industry to help the goal of“carbon peaking and carbon neutrality”.展开更多
In order to improve the cycle stability of La-Mg-Ni-Co type alloy electrode, rapid quenching technology was employed. The effects of rapid quenching on the microstructure and cycle stability of the alloy were investig...In order to improve the cycle stability of La-Mg-Ni-Co type alloy electrode, rapid quenching technology was employed. The effects of rapid quenching on the microstructure and cycle stability of the alloy were investigated. The obtained results show that the La2Mg(Ni0.85Co0.15)9M0.1 (M=B, Cr) alloy electrodes are composed of (La, Mg)Ni3 phase, LaNi5 phase and a small amount of the LaNi2 phase. A trace of the Ni2B phase exists in the as-cast MB alloy, and the Ni2B phase in the alloy nearly disappears after rapid quenching. Rapid quenching technology can slightly improve the cycling life of the alloy. When the quenching rate increases from 0 m·s-1 (As-cast is defined as quenching rate of 0 m·s-1) to 30 m·s-1, the cycle lives of the MB, MCr alloys enhance from 86 and 87 cycles to 106 and 119 cycles, respectively. On the other hand, the average capacity decay rates of the MB, MCr alloys decrease from 1.7172 and 1.7178 mAh·g-1·cycle-1 to 1.5751 and 1.3060 mAh·g-1·cycle-1 after 86 charge-discharges cycling, respectively.展开更多
Mm0.3Ml0.7Ni3.55Co0.75Mn0.4-Al0.3 alloy has high chemical activity and favorable plateaus pressure. Mg2Ni is in favor of high hydrogen storage capacity and low weight, but it is difficult to be activated. In order to ...Mm0.3Ml0.7Ni3.55Co0.75Mn0.4-Al0.3 alloy has high chemical activity and favorable plateaus pressure. Mg2Ni is in favor of high hydrogen storage capacity and low weight, but it is difficult to be activated. In order to improve the capacity and cycle performances of hydrogen-storage alloy electrodes, Mm0.3Ml0.7Ni3.55Co0.75Mn0.4-Al0.3-x%Mg2Ni(x=0, 5, 10, 30) composite hydrogen storage alloys prepared by two-step re-melting were investigated in this work. The influences of Mg2Ni content on the cycle stabilities were analyzed by electrochemical methods. It was observed by XRD that the main phase of all the alloys is LaNi5 and the crystal lattice parameters of LaNi5 are changed with the increasing of x value, i.e, a-axis and unit cell volume decrease and c-axis decreases nonlinearly. The c-axis of alloy with x=5 is larger than the others. With the increasing of x value, capacity retentions of the composite hydrogen storage alloys rise from 66.21% while x=0 to 82.04% while x=10, but the capacity retention of the composite alloy with 30% Mg2Ni declines because of its decreasing axial ratio. More over, the composite alloy with 5% Mg2Ni shows the best cycle stability and higher discharge capacity, and it is an appropriate candidate for battery materials.展开更多
To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) metho...To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) method based on thermal energy storage to eliminate frost off the outdoor coil surface was developed. Comparative experiments using both the stand reverse cycle defrosting (SRCD) method and the NRCD method were carried out on an experimental ASHP unit with a nominal 2.5 kW heating capacity. The results indicate that during defrosting operation, using the NRCD method improves discharge and suction pressures by 0.24 MPa and 0.19 MPa, respectively, shortens defrosting duration by 60%, and reduces the defrosting energy consumption by 48.1% in the experimental environment, compared with those by the use of SRCD method. Therefore, using the NRCD method can shorten the defrosting duration, improve the indoor thermal comfort, and reduce the defrosting energy consumption in defrosting.展开更多
In this paper, any two of the three anticorrosion agents, that is emulsifier (OP-10), soluble glass (Na2O·nSiO2) and glycerin (C3H8O3), were treated simultaneously on the surface of amorphous (a- ) MgNi + 5% Ml2M...In this paper, any two of the three anticorrosion agents, that is emulsifier (OP-10), soluble glass (Na2O·nSiO2) and glycerin (C3H8O3), were treated simultaneously on the surface of amorphous (a- ) MgNi + 5% Ml2Mg17(MI denotes the lanthanum-rich mish metal) electrode and the electrolyte. Effect of the synergistic anticorrosion treatment on charging/discharging cycle stability of the electrode was investigated. Contrasted with single treatment method, the cycling stability of the electrodes was further improved. The desirable synergistic anticorrosion method was that the electrode was treated by the soluble glass, and that OP-10 was added into the electrolyte. The cyclic voltammogram (CV) results of the electrode show clearly that the anticorrosion agent can change the electrochemical activity and mechanism of the electrode. The concentration of the anticorrosion agent in the electrolyte treated by the synergistic anticorrosion method was also investigated. The appropriate concentration of the anticorrosion agents in the electrolyte is 0.143% .展开更多
The paper presents the change in grain-size composition of lignite under cyclic freezing-thawing (FTC) and wetting-drying (WDC). The article shows that in the spring and autumn periods the lignites can be subjected to...The paper presents the change in grain-size composition of lignite under cyclic freezing-thawing (FTC) and wetting-drying (WDC). The article shows that in the spring and autumn periods the lignites can be subjected to repeated freezing-thawing and wetting-drying, which determines the possibility of changing their grain-size composition and structure. Experimental studies in laboratory conditions on the influence of cyclic freezing-thawing (FTC) and wetting-drying (WDC) on the quality indicators of lignites have been carried out, their granulometric (fractional) composition has been studied. Freezing-thawing cycle conditions are as follows (FTC): minimum exposure temperature: -20°C;maximum: +5°C;relative humidity: 30%;number of processing cycles: 3. Wetting-drying cycles are as follows (WDC): drying temperatures are +20, +40, +60, +80°C, drying time 90 minutes, the coals are further subjected to rain (soaking) for a period of water saturation to humidity of 30% - 40% and dry again. The number of wetting-drying cycles is 3 times. The tests have revealed the destructive effects of FTC and WDC on the samples of lower metamorphic grade coal, and the cycles of wet-dry lead to the much higher yield of fine sizes (-6+0;-13+0 mm) than the cycles of freeze-thaw. Furthermore, it is found that the increase in the yield of fines depends on the heating temperature: coal disintegration proceeds more intensively at a higher temperature of drying.展开更多
Objective:The relationship between serum beta human chorionic gonadotropin(β-hCG)levels of patients(7 days after the transplantation of frozen-thawed embryos)and the pregnancy outcomes was investigated.Methods:This s...Objective:The relationship between serum beta human chorionic gonadotropin(β-hCG)levels of patients(7 days after the transplantation of frozen-thawed embryos)and the pregnancy outcomes was investigated.Methods:This study was designed as a retrospective clinical trial of 366 women who underwent frozen-thawed embryo transfers(FETs)in artificial cycles.Patients were divided into three groups:clinical pregnancy group,biochemical pregnancy group,and non-pregnant group according to their pregnancy outcomes.Serumβ-hCG levels were tested on day 4,7,9,11 and 14 after FET.Results:In the clinical pregnancy group,the serumβ-hCG levels after 7-day post-transplantation were significantly elevated(16.20 IU/L vs.3.07 vs.0.1 IU/L;P<0.05)compared with the other two groups.Furthermore,it was found that Area Under Curve(AUC=0.96)was significant with cut-off value higher than 4.26 IU/L(sensitivity=92.3%,specificity=90.2%)to predict the clinical pregnancy outcomes in the receiver operating characteristic(ROC)analysis ofβ-hCG concentrations on day 7 of post-transplantation.Conclusion:Our results suggested that the elevated serumβ-hCG levels on day 7 of post-transplantation could predict the positive clinical pregnancy outcomes in artificial FET cycles.展开更多
The structure and electrochemical properties of a new low cobalt hydrogen storage electrode alloys La1-xLixNi3.2Co0.3Al0.3 (0≤x≤0.2) were investigated with a different additions of Li in replacement of La. With the ...The structure and electrochemical properties of a new low cobalt hydrogen storage electrode alloys La1-xLixNi3.2Co0.3Al0.3 (0≤x≤0.2) were investigated with a different additions of Li in replacement of La. With the increase of Li contents the maximum discharge capacity increases from 240 mAh·g-1(x=0) to 328.4 mAh·g-1(x=0.1) and the cycle stability is improved correspondingly. The capacity decay can remain 28.6% (x=0.2) after 230 charge/discharge cycles. The high rate discharge(HRD) ability of the alloys(x≤0.1) is improved and the best HRD is 34.1%(x=0.1) under the discharge current density 1200 mA·g-1. It is found that the prepared alloys are basically composed of LaNi5 as matrix phase and LaNi3 as second phase(x≤0.1). But the abundance of LaNi3 phase dramatically decreases with increasing x. When x=0.2, a new phase Al(NiCo)3 is formed.展开更多
The high-energy consumption and high construction density of 5G base stations have greatly increased the demand for backup energy storage batteries.To maximize overall benefits for the investors and operators of base ...The high-energy consumption and high construction density of 5G base stations have greatly increased the demand for backup energy storage batteries.To maximize overall benefits for the investors and operators of base station energy storage,we proposed a bi-level optimization model for the operation of the energy storage,and the planning of 5G base stations considering the sleep mechanism.A multi-base station cooperative system composed of 5G acer stations was considered as the research object,and the outer goal was to maximize the net profit over the complete life cycle of the energy storage.Furthermore,the power and capacity of the energy storage configuration were optimized.The inner goal included the sleep mechanism of the base station,and the optimization of the energy storage charging and discharging strategy,for minimizing the daily electricity expenditure of the 5G base station system.Additionally,genetic algorithm and mixed integer programming were used to solve the bi-level optimization model,analyze the numerical example test comparison of the three types of batteries and the net income of the configuration,and finally verify the validity of the model.Furthermore,the sleep mechanism,the charging and discharging strategy for energy consumption,and the economic benefits for the operators were investigated to provide reference for the 5G base station energy storage configuration.展开更多
Sodium-ion capacitors(SICs)are extremely promising due to the combined merits of high energy-power characteristics and considerable price advantage.However,it is still difficult to achieve high energypower outputs and...Sodium-ion capacitors(SICs)are extremely promising due to the combined merits of high energy-power characteristics and considerable price advantage.However,it is still difficult to achieve high energypower outputs and cycle stability in a typical configuration of the metal-based battery-type anode and activated carbon capacitor-type cathode due to the kinetic mismatching.In this work,a carbon nanosheet(PSCS-600)with large interlayer spacing of 0.41 nm derived from the bio-waste pine cone shell was prepared.Besides,the covalent triazine framework derived carbon(OPDN-CTF-A)was obtained through ionothermal synthesis strategy,exhibiting beneficial hierarchical pores(0.5-6 nm)and high heteroatoms(5.6 at%N,6.6 at%O).On this basis,the all-carbon SICs were fabricated by the integration of PSCS-600 anode and OPDN-CTF-A cathode.The device delivered high energy density 111 Wh kg^(-1),high power output of 14,200 W kg^(-1) and ultra-stable cycling life(~90.7%capacitance retention after 10,000 cycles).This work provides new ideas in fabricating carbon-carbon architectural SICs with high energy storage for practical application.展开更多
The rare earth based hydrogen storage alloys MmxM1 1 - x ( Ni3.55 Co0.75 Mn0.4 A10.3 ) ( x = 0 ~ 0.5 ) were investigated in this work.Adjusted Ml: Mm ratio to change the content of La,Ce,Pr and Nd in the alloys and t...The rare earth based hydrogen storage alloys MmxM1 1 - x ( Ni3.55 Co0.75 Mn0.4 A10.3 ) ( x = 0 ~ 0.5 ) were investigated in this work.Adjusted Ml: Mm ratio to change the content of La,Ce,Pr and Nd in the alloys and then to change the phase structure, the influences of phase structure on the electrochemical properties were analyzed.The results indicate that the main phase of all alloys is LaNi5 with CaCu5 type structure and the crystal lattices constants of LaNi5 are changed with increasing x value, i.e, decreased a-axis, increased c-axis and axis ratio and nonlinear decreased crystal volume.The crystal volume of the alloy with x = 0.3 is larger than others.There is second phase A1LaNi4 in alloys when x≥0.3, which decrease the discharge capacity, but increase the cycling stability and high rate discharge ability.Compared comprehensively, the alloy with x = 0.3 shows the higher discharge capacity and the better cycling stability.展开更多
By means of the pore-level simulation, the characteristics of gas-water flow and gas-water distribution during the alternative displacement of gas and water were observed directly from etched-glass micromodel. The res...By means of the pore-level simulation, the characteristics of gas-water flow and gas-water distribution during the alternative displacement of gas and water were observed directly from etched-glass micromodel. The results show that gas-water distribution styles are divided into continuous phase type and separate phase type. The water lock exists in pore and throat during the process of gas-water displacement, and it reduces the gas flow-rate and has some effects on the recovery efficiency during the operation of gas storage. According to the experimental results of aquifer gas storage in X area, the differences in available extent among reservoirs are significant, and the availability of pore space is 33% 45%.展开更多
Aiming to elucidate the hydrogen absorption/desorption cycling properties of Mg-based alloys with in-situ formed Mg_(2)Ni and LaH_(x)(x=2,3)nanocrystallines,the hydrogen storage cycle stability,hydriding/dehydriding c...Aiming to elucidate the hydrogen absorption/desorption cycling properties of Mg-based alloys with in-situ formed Mg_(2)Ni and LaH_(x)(x=2,3)nanocrystallines,the hydrogen storage cycle stability,hydriding/dehydriding cycling kinetics and thermodynamic stability of the experimental alloys have been investigated in detail.The results show that the Mg-Ni-La alloys exhibit improved hydrogen storage cycling properties and can remain storage hydrogen above 5.5 wt%after 200 cycles.With the increase of cycling numbers,the dehydrogenation rates of the experimental samples increase firstly and then gradually decrease,and eventually maintain relative stable state.Microstructure observation reveals that powders sintering and hydrogen decrepitation both exist during hydrogen absorption/desorption cycles due to repeated volume expansion and contraction.Meanwhile,the in-situ formed LaH_(x)(x=2,3)and Mg_(2)Ni nanocrystallines stabilize the microstructures of the particles and hinder the powders sintering.After 200 cycles,the average particle size of the experimental samples decreases and the specific surface area apparently increases,which leads to the decomposition temperatures of MgH_(2)and Mg_(2)NiH_(4)slightly shift to lower temperatures.Moreover,Mg_(2)Ni and LaH_(x)(x=2,3)have been proven to be stable catalysts during long-term cycling,which can still uniformly distribute within the powders after 200 cycles.展开更多
A hydrogen storage electrode alloy La_ 0.7Mg_ 0.3Ni_ 2.98Co_ 0.52 was obtained by electromagnetism inductive melting of alloys such as La, Mg, Ni and Co. XRD analyses indicate that the microstructure of the prepared a...A hydrogen storage electrode alloy La_ 0.7Mg_ 0.3Ni_ 2.98Co_ 0.52 was obtained by electromagnetism inductive melting of alloys such as La, Mg, Ni and Co. XRD analyses indicate that the microstructure of the prepared alloy was composed of LaNi_5 phase as matrix and another unknown phase as secondary phase. In this experiment, the highest discharge capacity of alloy is 378 mAh·g -1 at 293 K, which is 20% higher than the discharge capacity of LaNi_5-type alloys. The alloy was activated after two cycles and the discharge potential is high and stable, and more than 90% of the discharge time is in a voltage higher than 1.2 V. However, the cycle stability is poor as practical application, to improve the cycle life of the alloy becomes the key factor. Moreover, the loose structure of the alloy is maybe one reason that makes the cycle stability capacity of the alloy decrease by SEM.展开更多
Quasicrystals have long-range quasi-periodic translational ordering and non-crystallographic rotational symmetry.Al-Cu-Fe quasicrystals have great potential for lithium storage because of their high Al content and a l...Quasicrystals have long-range quasi-periodic translational ordering and non-crystallographic rotational symmetry.Al-Cu-Fe quasicrystals have great potential for lithium storage because of their high Al content and a large number of defects in the structure.In our previous study(J.Alloys Compd.805(2019)942)we showed that Al-Cu-Fe quasicrystals have good initial capacity whereas its cycle stability is poor.In the present study,graphite/AlCuFe is prepared by the mechanical alloying method.The results show that graphite/AlCuFe quasicrystal composites are successfully synthesized by planetary ball milling at 550 rpm for 80 h.The quasicrystal particle size decreases and the amorphous graphite forms onion-like carbon(OLC)when the two phases mix evenly.OLC forms on the surface of the Al-Cu-Fe quasicrystalline powder.Charge and discharge tests show that graphite/AlCuFe quasicrystal composites have high-stability capacity of 480 mAh/g after 20 cycles,which is larger than the sum of capacities of graphite and Al-Cu-Fe quasicrystals.展开更多
Thermochemical energy storage based on CaO/CaCO_(3)cycles has obtained significant attention as an alternative energy storage solution for concentrated solar power plants.In view of the applicability of fluidized bed ...Thermochemical energy storage based on CaO/CaCO_(3)cycles has obtained significant attention as an alternative energy storage solution for concentrated solar power plants.In view of the applicability of fluidized bed reactors for CaO/CaCO_(3)heat storage,it is imperative to study the factors related to the heat release performance of CaO.This work presents an exothermic experiment on calcined limestone under fluidization,exploring the impact of initial temperature,CO_(2)concentration,particle size,superficial gas velocity,and number of cycles on the exothermic performance of CaO.The result indicates that CaO with high initial temperature leads to higher exothermic temperature,with better exothermic stability under cycles.An optimal initial temperature range of 600℃-650℃exists with an actual CaO conversion rate deviating merely 2%from theoretical conversion.Higher CO_(2)concentration augments the exothermic temperature and rate of CaO,while also improves the effective conversion of CaO.Nevertheless,high CO_(2)concentrations exacerbate the sintering and deactivation of CaO.High superficial gas velocity and small particle size shorten the exothermic time by increasing heat dissipation,but has minimal effect on the exothermic properties.Finally,the exothermic properties of CaO under fluidized and static conditions are studied.The result shows that exothermic temperature and exothermic rate of CaO under fluidization are enhanced,displaying higher heat storage performance than that under static state.This study provides valuable insights for optimizing the exothermic performance of CaO in fluidized bed reactors,contributing to advanced thermochemical energy storage for concentrated solar power plants.展开更多
基金the National Natural Science Foundation of China,Grant Number 31800581.
文摘Ellagic acid(EA)is a natural antioxidant,widely present in a lot of forms’soft fruits,nuts,and other plant tissues,and helpful for promoting human health;however,its protective effect on postharvest fruit and improving the quality index of postharvest fruit have rarely been studied.In this experiment,the strawberries were soaked in 0,100,200,300,400,and 500 mg L^(−1) EA,respectively,and the influential EA on fruit quality and the antioxidant system of strawberries were studied.Compared with the control,EA treatment can reduce the browning degree and rotting rate of strawberry fruit during storage and augment the soluble solid content(SSC).EA treatment can also increase the content of related stuff and enzyme activity in antioxidant systems;the gene expression level of polyphenol oxidase(PPO)in strawberries treated with EA was always down-regulated,correspondingly,the expression of other antioxidant enzyme genes was enhanced.Among the strawberry fruits treated with EA of different concentrations,300 mg L^(−1) EA had the best effect in the process of strawberry preservation.The results suggested that the proper concentration of exogenous EA at 300 mg L−1 could maintain strawberries’quality and enhance the antioxidant system by improving the activities of antioxidative enzymes and the ascorbateglutathione(AsA-GSH)cycle during storage.
基金the National Natural Science Foundation of China(Nos.52374147,42372328,and U23B2091)National Key Research and Development Program of China(No.2023YFC3804200)Xinjiang Uygur Autonomous Region Science and Technology Major Program(No.2023A01002).
文摘Underground pumped storage power plant(UPSP)is an innovative concept for space recycling of abandoned mines.Its realization requires better understanding of the dynamic performance and durability of reservoir rock.This paper conducted ultrasonic detection,split Hopkinson pressure bar(SHPB)impact,mercury intrusion porosimetry(MIP),and backscatter electron observation(BSE)tests to investigate the dynamical behaviour and microstructure of sandstone with cyclical dry-wet damage.A coupling FEM-DEM model was constructed for reappearing mesoscopic structure damage.The results show that dry-wet cycles decrease the dynamic compressive strength(DCS)with a maximum reduction of 39.40%,the elastic limit strength is reduced from 41.75 to 25.62 MPa.The sieved fragments obtain the highest crack growth rate during the 23rd dry-wet cycle with a predictable life of 25 cycles for each rock particle.The pore fractal features of the macropores and micro-meso pores show great differences between the early and late cycles,which verifies the computational statistics analysis of particle deterioration.The numerical results show that the failure patterns are governed by the strain in pre-peak stage and the shear cracks are dominant.The dry-wet cycles reduce the energy transfer efficiency and lead to the discretization of force chain and crack fields.
基金the financial support from the National Natural Science Foundation of China(No.52074217)the Natural Science Basic Research Program of Shaanxi Province(No.2021JLM-26).
文摘The concept of the carbon cycle in the old goaf of a coal mine based on CO_(2)utilization and storage was put forward adhering to the principle of low-carbon development,utilization of space resources in old goafs,and associated gas resources development.Firstly,the evolution characteristics of overburden fissures in the goaf of the case was studied using a two-dimensional physical similarity simulation test,the sealing performance of the caprocks after stabilization was analyzed,and the fissures were counted and classi-fied.Then,the process of gaseous CO_(2)injection in the connected fissure was simulated by Ansys Fluent software,and the migration law and distribution characteristics of CO_(2)under the condition of gaseous CO_(2)injection were analyzed.Finally,the estimation models of free CO_(2)storage capacity in the old goaf were constructed considering the proportion of connected fissure and the effectiveness of CO_(2)injection.The CO_(2)storage capacity in the old goaf of the case coal mine was estimated.The results showed that a caprock group of“hard-thickness low-permeability hard-thickness”was formed after the caprock-fissures system in the goaf of the case tended to be stable vertically.The connected fissure,occlude cracks,and micro-fractures in the goaf accounted for 85.5%,8.5%,and 6%of the total fissures,respectively.Gaseous CO_(2)first migrated to the bottom of the connected fissure after CO_(2)was injected into the goaf,then spread horizontally along the bottom of the connected fissure after reaching the bottom,and finally spread longitudinally after filling the bottom of the entire connected fissure.The theoretical and effective storage capacities of free CO_(2)at normal temperature and pressure in the old goaf of the case were 9757 and 7477 t,respectively.The effective storage capacity of free CO_(2)at normal temperature and pressure in the old goaf after all minefield mined was 193404 t.The research can provide some reference for the coal mining industry to help the goal of“carbon peaking and carbon neutrality”.
基金This work was financially supported by National Natural Science Foundations of China (No.50131040)Key Technologies R & D Program of Inner Mongolia (No.20050205)College Scientific Research Project of Inner Mongolia (No.NJ05064).
文摘In order to improve the cycle stability of La-Mg-Ni-Co type alloy electrode, rapid quenching technology was employed. The effects of rapid quenching on the microstructure and cycle stability of the alloy were investigated. The obtained results show that the La2Mg(Ni0.85Co0.15)9M0.1 (M=B, Cr) alloy electrodes are composed of (La, Mg)Ni3 phase, LaNi5 phase and a small amount of the LaNi2 phase. A trace of the Ni2B phase exists in the as-cast MB alloy, and the Ni2B phase in the alloy nearly disappears after rapid quenching. Rapid quenching technology can slightly improve the cycling life of the alloy. When the quenching rate increases from 0 m·s-1 (As-cast is defined as quenching rate of 0 m·s-1) to 30 m·s-1, the cycle lives of the MB, MCr alloys enhance from 86 and 87 cycles to 106 and 119 cycles, respectively. On the other hand, the average capacity decay rates of the MB, MCr alloys decrease from 1.7172 and 1.7178 mAh·g-1·cycle-1 to 1.5751 and 1.3060 mAh·g-1·cycle-1 after 86 charge-discharges cycling, respectively.
基金Project Supported bythe Talents Development Foundation of Inner Mongolia Autonomous Region (200608)
文摘Mm0.3Ml0.7Ni3.55Co0.75Mn0.4-Al0.3 alloy has high chemical activity and favorable plateaus pressure. Mg2Ni is in favor of high hydrogen storage capacity and low weight, but it is difficult to be activated. In order to improve the capacity and cycle performances of hydrogen-storage alloy electrodes, Mm0.3Ml0.7Ni3.55Co0.75Mn0.4-Al0.3-x%Mg2Ni(x=0, 5, 10, 30) composite hydrogen storage alloys prepared by two-step re-melting were investigated in this work. The influences of Mg2Ni content on the cycle stabilities were analyzed by electrochemical methods. It was observed by XRD that the main phase of all the alloys is LaNi5 and the crystal lattice parameters of LaNi5 are changed with the increasing of x value, i.e, a-axis and unit cell volume decrease and c-axis decreases nonlinearly. The c-axis of alloy with x=5 is larger than the others. With the increasing of x value, capacity retentions of the composite hydrogen storage alloys rise from 66.21% while x=0 to 82.04% while x=10, but the capacity retention of the composite alloy with 30% Mg2Ni declines because of its decreasing axial ratio. More over, the composite alloy with 5% Mg2Ni shows the best cycle stability and higher discharge capacity, and it is an appropriate candidate for battery materials.
基金Project(50606007) supported by the National Natural Science Foundation of China
文摘To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) method based on thermal energy storage to eliminate frost off the outdoor coil surface was developed. Comparative experiments using both the stand reverse cycle defrosting (SRCD) method and the NRCD method were carried out on an experimental ASHP unit with a nominal 2.5 kW heating capacity. The results indicate that during defrosting operation, using the NRCD method improves discharge and suction pressures by 0.24 MPa and 0.19 MPa, respectively, shortens defrosting duration by 60%, and reduces the defrosting energy consumption by 48.1% in the experimental environment, compared with those by the use of SRCD method. Therefore, using the NRCD method can shorten the defrosting duration, improve the indoor thermal comfort, and reduce the defrosting energy consumption in defrosting.
基金Project supported by the National Natural Science Foundation of China (20363001) the Project in Specific Technological R & D Fund Program for Research Institutes from Ministry of Science and Technology of the PRC (2004EG113030)the Key Project in International Science and Technology Cooperation from Ministry of Science and Technology of the PRC (2005DFA50250)
文摘In this paper, any two of the three anticorrosion agents, that is emulsifier (OP-10), soluble glass (Na2O·nSiO2) and glycerin (C3H8O3), were treated simultaneously on the surface of amorphous (a- ) MgNi + 5% Ml2Mg17(MI denotes the lanthanum-rich mish metal) electrode and the electrolyte. Effect of the synergistic anticorrosion treatment on charging/discharging cycle stability of the electrode was investigated. Contrasted with single treatment method, the cycling stability of the electrodes was further improved. The desirable synergistic anticorrosion method was that the electrode was treated by the soluble glass, and that OP-10 was added into the electrolyte. The cyclic voltammogram (CV) results of the electrode show clearly that the anticorrosion agent can change the electrochemical activity and mechanism of the electrode. The concentration of the anticorrosion agent in the electrolyte treated by the synergistic anticorrosion method was also investigated. The appropriate concentration of the anticorrosion agents in the electrolyte is 0.143% .
文摘The paper presents the change in grain-size composition of lignite under cyclic freezing-thawing (FTC) and wetting-drying (WDC). The article shows that in the spring and autumn periods the lignites can be subjected to repeated freezing-thawing and wetting-drying, which determines the possibility of changing their grain-size composition and structure. Experimental studies in laboratory conditions on the influence of cyclic freezing-thawing (FTC) and wetting-drying (WDC) on the quality indicators of lignites have been carried out, their granulometric (fractional) composition has been studied. Freezing-thawing cycle conditions are as follows (FTC): minimum exposure temperature: -20°C;maximum: +5°C;relative humidity: 30%;number of processing cycles: 3. Wetting-drying cycles are as follows (WDC): drying temperatures are +20, +40, +60, +80°C, drying time 90 minutes, the coals are further subjected to rain (soaking) for a period of water saturation to humidity of 30% - 40% and dry again. The number of wetting-drying cycles is 3 times. The tests have revealed the destructive effects of FTC and WDC on the samples of lower metamorphic grade coal, and the cycles of wet-dry lead to the much higher yield of fine sizes (-6+0;-13+0 mm) than the cycles of freeze-thaw. Furthermore, it is found that the increase in the yield of fines depends on the heating temperature: coal disintegration proceeds more intensively at a higher temperature of drying.
文摘Objective:The relationship between serum beta human chorionic gonadotropin(β-hCG)levels of patients(7 days after the transplantation of frozen-thawed embryos)and the pregnancy outcomes was investigated.Methods:This study was designed as a retrospective clinical trial of 366 women who underwent frozen-thawed embryo transfers(FETs)in artificial cycles.Patients were divided into three groups:clinical pregnancy group,biochemical pregnancy group,and non-pregnant group according to their pregnancy outcomes.Serumβ-hCG levels were tested on day 4,7,9,11 and 14 after FET.Results:In the clinical pregnancy group,the serumβ-hCG levels after 7-day post-transplantation were significantly elevated(16.20 IU/L vs.3.07 vs.0.1 IU/L;P<0.05)compared with the other two groups.Furthermore,it was found that Area Under Curve(AUC=0.96)was significant with cut-off value higher than 4.26 IU/L(sensitivity=92.3%,specificity=90.2%)to predict the clinical pregnancy outcomes in the receiver operating characteristic(ROC)analysis ofβ-hCG concentrations on day 7 of post-transplantation.Conclusion:Our results suggested that the elevated serumβ-hCG levels on day 7 of post-transplantation could predict the positive clinical pregnancy outcomes in artificial FET cycles.
基金This work was financially supported by the Industrial Project of Science and Technology Office of Shannxi Prov-ince (2003K07G11)State Key Project of Education Ministry(104266)
文摘The structure and electrochemical properties of a new low cobalt hydrogen storage electrode alloys La1-xLixNi3.2Co0.3Al0.3 (0≤x≤0.2) were investigated with a different additions of Li in replacement of La. With the increase of Li contents the maximum discharge capacity increases from 240 mAh·g-1(x=0) to 328.4 mAh·g-1(x=0.1) and the cycle stability is improved correspondingly. The capacity decay can remain 28.6% (x=0.2) after 230 charge/discharge cycles. The high rate discharge(HRD) ability of the alloys(x≤0.1) is improved and the best HRD is 34.1%(x=0.1) under the discharge current density 1200 mA·g-1. It is found that the prepared alloys are basically composed of LaNi5 as matrix phase and LaNi3 as second phase(x≤0.1). But the abundance of LaNi3 phase dramatically decreases with increasing x. When x=0.2, a new phase Al(NiCo)3 is formed.
基金supported by the State Grid Science and Technology Project(KJ21-1-56).
文摘The high-energy consumption and high construction density of 5G base stations have greatly increased the demand for backup energy storage batteries.To maximize overall benefits for the investors and operators of base station energy storage,we proposed a bi-level optimization model for the operation of the energy storage,and the planning of 5G base stations considering the sleep mechanism.A multi-base station cooperative system composed of 5G acer stations was considered as the research object,and the outer goal was to maximize the net profit over the complete life cycle of the energy storage.Furthermore,the power and capacity of the energy storage configuration were optimized.The inner goal included the sleep mechanism of the base station,and the optimization of the energy storage charging and discharging strategy,for minimizing the daily electricity expenditure of the 5G base station system.Additionally,genetic algorithm and mixed integer programming were used to solve the bi-level optimization model,analyze the numerical example test comparison of the three types of batteries and the net income of the configuration,and finally verify the validity of the model.Furthermore,the sleep mechanism,the charging and discharging strategy for energy consumption,and the economic benefits for the operators were investigated to provide reference for the 5G base station energy storage configuration.
基金the support from the National Key Research and Development Program(No.2018YFB1107500)the National Natural Science Foundation of China(No.51503024)+3 种基金the Fundamental Research Funds for the Central Universities(No.DUT17RC(3)003)the National Natural Science Foundation of the Joint Fund Key Projects(No.U1663226)the Dalian Youth Science and Technology Star Project Support Program(No.2017RQ104)the Scientific Research Foundation for Doctor,Liaoning Province of China(No.20170520083)。
文摘Sodium-ion capacitors(SICs)are extremely promising due to the combined merits of high energy-power characteristics and considerable price advantage.However,it is still difficult to achieve high energypower outputs and cycle stability in a typical configuration of the metal-based battery-type anode and activated carbon capacitor-type cathode due to the kinetic mismatching.In this work,a carbon nanosheet(PSCS-600)with large interlayer spacing of 0.41 nm derived from the bio-waste pine cone shell was prepared.Besides,the covalent triazine framework derived carbon(OPDN-CTF-A)was obtained through ionothermal synthesis strategy,exhibiting beneficial hierarchical pores(0.5-6 nm)and high heteroatoms(5.6 at%N,6.6 at%O).On this basis,the all-carbon SICs were fabricated by the integration of PSCS-600 anode and OPDN-CTF-A cathode.The device delivered high energy density 111 Wh kg^(-1),high power output of 14,200 W kg^(-1) and ultra-stable cycling life(~90.7%capacitance retention after 10,000 cycles).This work provides new ideas in fabricating carbon-carbon architectural SICs with high energy storage for practical application.
文摘The rare earth based hydrogen storage alloys MmxM1 1 - x ( Ni3.55 Co0.75 Mn0.4 A10.3 ) ( x = 0 ~ 0.5 ) were investigated in this work.Adjusted Ml: Mm ratio to change the content of La,Ce,Pr and Nd in the alloys and then to change the phase structure, the influences of phase structure on the electrochemical properties were analyzed.The results indicate that the main phase of all alloys is LaNi5 with CaCu5 type structure and the crystal lattices constants of LaNi5 are changed with increasing x value, i.e, decreased a-axis, increased c-axis and axis ratio and nonlinear decreased crystal volume.The crystal volume of the alloy with x = 0.3 is larger than others.There is second phase A1LaNi4 in alloys when x≥0.3, which decrease the discharge capacity, but increase the cycling stability and high rate discharge ability.Compared comprehensively, the alloy with x = 0.3 shows the higher discharge capacity and the better cycling stability.
基金Project(2011ZX05013-002)supported by National Science and Technology Major Projects of China
文摘By means of the pore-level simulation, the characteristics of gas-water flow and gas-water distribution during the alternative displacement of gas and water were observed directly from etched-glass micromodel. The results show that gas-water distribution styles are divided into continuous phase type and separate phase type. The water lock exists in pore and throat during the process of gas-water displacement, and it reduces the gas flow-rate and has some effects on the recovery efficiency during the operation of gas storage. According to the experimental results of aquifer gas storage in X area, the differences in available extent among reservoirs are significant, and the availability of pore space is 33% 45%.
基金supported by Natural Science Foundation of Shaanxi Province,China(2017JM5079)The 111 project(No.B08040)is also acknowledged.
文摘Aiming to elucidate the hydrogen absorption/desorption cycling properties of Mg-based alloys with in-situ formed Mg_(2)Ni and LaH_(x)(x=2,3)nanocrystallines,the hydrogen storage cycle stability,hydriding/dehydriding cycling kinetics and thermodynamic stability of the experimental alloys have been investigated in detail.The results show that the Mg-Ni-La alloys exhibit improved hydrogen storage cycling properties and can remain storage hydrogen above 5.5 wt%after 200 cycles.With the increase of cycling numbers,the dehydrogenation rates of the experimental samples increase firstly and then gradually decrease,and eventually maintain relative stable state.Microstructure observation reveals that powders sintering and hydrogen decrepitation both exist during hydrogen absorption/desorption cycles due to repeated volume expansion and contraction.Meanwhile,the in-situ formed LaH_(x)(x=2,3)and Mg_(2)Ni nanocrystallines stabilize the microstructures of the particles and hinder the powders sintering.After 200 cycles,the average particle size of the experimental samples decreases and the specific surface area apparently increases,which leads to the decomposition temperatures of MgH_(2)and Mg_(2)NiH_(4)slightly shift to lower temperatures.Moreover,Mg_(2)Ni and LaH_(x)(x=2,3)have been proven to be stable catalysts during long-term cycling,which can still uniformly distribute within the powders after 200 cycles.
文摘A hydrogen storage electrode alloy La_ 0.7Mg_ 0.3Ni_ 2.98Co_ 0.52 was obtained by electromagnetism inductive melting of alloys such as La, Mg, Ni and Co. XRD analyses indicate that the microstructure of the prepared alloy was composed of LaNi_5 phase as matrix and another unknown phase as secondary phase. In this experiment, the highest discharge capacity of alloy is 378 mAh·g -1 at 293 K, which is 20% higher than the discharge capacity of LaNi_5-type alloys. The alloy was activated after two cycles and the discharge potential is high and stable, and more than 90% of the discharge time is in a voltage higher than 1.2 V. However, the cycle stability is poor as practical application, to improve the cycle life of the alloy becomes the key factor. Moreover, the loose structure of the alloy is maybe one reason that makes the cycle stability capacity of the alloy decrease by SEM.
文摘Quasicrystals have long-range quasi-periodic translational ordering and non-crystallographic rotational symmetry.Al-Cu-Fe quasicrystals have great potential for lithium storage because of their high Al content and a large number of defects in the structure.In our previous study(J.Alloys Compd.805(2019)942)we showed that Al-Cu-Fe quasicrystals have good initial capacity whereas its cycle stability is poor.In the present study,graphite/AlCuFe is prepared by the mechanical alloying method.The results show that graphite/AlCuFe quasicrystal composites are successfully synthesized by planetary ball milling at 550 rpm for 80 h.The quasicrystal particle size decreases and the amorphous graphite forms onion-like carbon(OLC)when the two phases mix evenly.OLC forms on the surface of the Al-Cu-Fe quasicrystalline powder.Charge and discharge tests show that graphite/AlCuFe quasicrystal composites have high-stability capacity of 480 mAh/g after 20 cycles,which is larger than the sum of capacities of graphite and Al-Cu-Fe quasicrystals.
基金Financial supports from the National Natural Science Foundation of China(52276204)the Shandong Provincial Natural Science Foundation(ZR2020ME188)。
文摘Thermochemical energy storage based on CaO/CaCO_(3)cycles has obtained significant attention as an alternative energy storage solution for concentrated solar power plants.In view of the applicability of fluidized bed reactors for CaO/CaCO_(3)heat storage,it is imperative to study the factors related to the heat release performance of CaO.This work presents an exothermic experiment on calcined limestone under fluidization,exploring the impact of initial temperature,CO_(2)concentration,particle size,superficial gas velocity,and number of cycles on the exothermic performance of CaO.The result indicates that CaO with high initial temperature leads to higher exothermic temperature,with better exothermic stability under cycles.An optimal initial temperature range of 600℃-650℃exists with an actual CaO conversion rate deviating merely 2%from theoretical conversion.Higher CO_(2)concentration augments the exothermic temperature and rate of CaO,while also improves the effective conversion of CaO.Nevertheless,high CO_(2)concentrations exacerbate the sintering and deactivation of CaO.High superficial gas velocity and small particle size shorten the exothermic time by increasing heat dissipation,but has minimal effect on the exothermic properties.Finally,the exothermic properties of CaO under fluidized and static conditions are studied.The result shows that exothermic temperature and exothermic rate of CaO under fluidization are enhanced,displaying higher heat storage performance than that under static state.This study provides valuable insights for optimizing the exothermic performance of CaO in fluidized bed reactors,contributing to advanced thermochemical energy storage for concentrated solar power plants.