In this study,the current situation of pluriactivity in mountainous and hilly rural areas of Sichuan province was analyzed using representative sample survey data and natural factor data calculated based on 30 m-resol...In this study,the current situation of pluriactivity in mountainous and hilly rural areas of Sichuan province was analyzed using representative sample survey data and natural factor data calculated based on 30 m-resolution DEM and GIS.Moreover,using logistic regression model,a quantitative analysis was conducted on factors influencing pluriactivity in terms of individuals,households,communities and natural environmental conditions.The results showed that,(1) only 17.77% of rural laborers in mountainous and hilly areas of Sichuan province were engaged in pluriactivity.Geographically,pluriactivity was mainly chosen according to the "proximity principle",and was concentrated in construction and service industries;(2) the following factors have a significant influence on whether rural laborers in hilly areas engage in pluriactivity:gender,number of years of education,marriage,number of laborers and time to towns.Those with little influence include:age,health,family size,arable land per capita and per capita income,whether there are elderly people over 75 years and children less than 3 years.According to the main factors affecting pluriactivity,the government should enhance vocational skills training for rural laborers in mountainous and hilly areas,especially for female laborers,further improve transport accessibility and encourage rural laborers,especially female laborers to move into pluriactivity to increase the income of farm households.展开更多
The power grid operation process is complex,and many operation process data involve national security,business secrets,and user privacy.Meanwhile,labeled datasets may exist in many different operation platforms,but th...The power grid operation process is complex,and many operation process data involve national security,business secrets,and user privacy.Meanwhile,labeled datasets may exist in many different operation platforms,but they cannot be directly shared since power grid data is highly privacysensitive.How to use these multi-source heterogeneous data as much as possible to build a power grid knowledge map under the premise of protecting privacy security has become an urgent problem in developing smart grid.Therefore,this paper proposes federated learning named entity recognition method for the power grid field,aiming to solve the problem of building a named entity recognition model covering the entire power grid process training by data with different security requirements.We decompose the named entity recognition(NER)model FLAT(Chinese NER Using Flat-Lattice Transformer)in each platform into a global part and a local part.The local part is used to capture the characteristics of the local data in each platform and is updated using locally labeled data.The global part is learned across different operation platforms to capture the shared NER knowledge.Its local gradients fromdifferent platforms are aggregated to update the global model,which is further delivered to each platform to update their global part.Experiments on two publicly available Chinese datasets and one power grid dataset validate the effectiveness of our method.展开更多
By using site observation data and establishing 3D model using ANSYS software, this paper has discussed the strain change of stratum stress during process of jacking-in and the impact of machine head on ground surface...By using site observation data and establishing 3D model using ANSYS software, this paper has discussed the strain change of stratum stress during process of jacking-in and the impact of machine head on ground surface under different frontal resistances. Analysis of the two cases shows that soil pressure reaches its maximum point when the soil is right above machine head, and soil stress will gradually decline when machine head passes over it. It also shows that impact brought by pipe-jacking construction on stress change of the surrounding soil is limited. The thesis suggest that road surface should be consolidated and soil condition be improved before construction to prevent loss and disaster caused by road surface deformation, jacking force can be increased so that jacking efficiency can be enhanced when ground stratum is well filled with soil, but the frontal resistance facing machine head should be equal to surrounding soil pressure in order to avoid rise of ground surface.展开更多
Collapsing gully erosion is a specific form of soil erosion types in the hilly granitic region of tropical and subtropical South China, and can result in extremely rapid water and soil loss. Knowledge of the soil phys...Collapsing gully erosion is a specific form of soil erosion types in the hilly granitic region of tropical and subtropical South China, and can result in extremely rapid water and soil loss. Knowledge of the soil physical and chemical properties of farmland influenced by collapsing gully erosion is important in understanding the development of soil quality. This study was conducted at the Wuli Watershed of the Tongcheng County, south of Hubei Province, China. The aim is to investigate soil physical and chemical properties of three soil layers (0-20, 20-40 and 40-60 cm) for two farmland types (paddy field and upland field) in three regions influenced by collapsing gully erosion. The three regions are described as follows: strongly influenced region (SIR), weakly influenced region (WIR) and non-influenced region (NIR). The results show that collapsing gully erosion significantly increased the soil gravel and sand content in paddy and upland fields, especially the surface soil in the SIR and WIR. In the 0-20 cm layer of the paddy field, the highest gravel content (250.94 g kg-1) was in the SIR and the lowest (78.67 g kg-1) was in the NIR, but in the upland filed, the surface soil (0-20 cm) of the SIR and the 40-60 cm soil layer for the NIR had the highest (177.13 g kg-1) and the lowest (59.96 g kg-1) values of gravel content, respectively. The distribution of gravel and sand decreased with depth in the three influenced regions, but silt and clay showed the inverse change. In the paddy field, the average of sand content decreased from 58.6 (in the SIR) to 49.0% (in the NIR), but the silt content was in a reverse order, increasing from 27.9 to 36.9%, and the average of the clay content of three regions showed no significant variation (P〈0.05). But in the upland filed, the sand, silt and clay fluctuated in the NIR and the WIR. Soils in the paddy and upland field were highly acidic (pH〈5.2) in the SIR and WIR; moreover lower nutrient contents (soil organic matter (SOM), total N and available N, P, K) existed in the SIR. In the 0-20 cm soil layer of the paddy field, compared with the NIR and the WIR, collapsing gully erosion caused a very sharp decrease in the SOM and total N of the SIR (5.23 and 0.56 g kg-1, respectively). But in the surface soil (0-20 cm) of the upland field, the highest SOM, total N, available N, available P and available K occurred in the NIR, and the lowest ones were in the SIR. Compared with the NIR, the cation exchange capacity (CEC) in the SIR and WIR was found to be relatively lower. These results suggest that collapsing gully erosion seriously affect the soil physical and chemical properties of farmland, lead to coarse particles accumulation in the field and decrease pH and nutrient levels.展开更多
In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–...In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–1(24.2 ton·day),and Run 11–2(37.1 ton·day).The mistake is due to an incorrect application of a small energy non-linearity(known as the BLS non-linearity)in making plots,but has no impact to the final results.Figures 2 and 3 are now updated in this note.展开更多
P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this m...P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversible lattice oxygen release. Here we systematically investigated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hindered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.展开更多
Global opinion on and perception of Tibetan attitudes and affairs have been heavily shaped by one group of Tibetans,namely the Dalai Lama and his fellow exiles.They have done so on the claim that they speak for all si...Global opinion on and perception of Tibetan attitudes and affairs have been heavily shaped by one group of Tibetans,namely the Dalai Lama and his fellow exiles.They have done so on the claim that they speak for all sixplus million Tibetans,overseas as well as in China.On this claim they also seek autonomy of a so-called Greater Tibet from Beijing,which is the展开更多
We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total ex...We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total exposure of 100.7 ton·day with liquid xenon.With robust estimates of the dominant background spectra,we perform sensitive searches on solar axions and neutrinos with enhanced magnetic moment.It is found that the axionelectron coupling gAe<4.6×10^(-12) for an axion mass less than 0.1 keV/c^(2) and the neutrino magnetic moment μv<4.9×10^(-11)μB at 90%confidence level.The observed excess from XENON1 T is within our experimental constraints.展开更多
Because of its large capacity,high efficiency and energy savings,the subway has gradually become the primary mode of transportation for citizens.A high density of passengers exists within a large-passenger-flow subway...Because of its large capacity,high efficiency and energy savings,the subway has gradually become the primary mode of transportation for citizens.A high density of passengers exists within a large-passenger-flow subway station,and the number of casualties and injuries during a fire emergency is substantial.In this paper,Pathfinder software and on-site measured data of Pingzhou station in Shenzhen(China)were utilized to simulate a fire emergency evacuation in a large-passenger-flow subway station.The Required Safe Egress Time(RSET),number of passengers and flow rates of stairs and escalators were analysed for three fire evacuation scenarios:train fire,platform fire and hall fire.The evacuation time of the train fire,which was 1173 s,was the longest,and 3621 occupants needed to evacuate when the train was fully loaded.Occupants could not complete the evacuation within 6 mins in all three fire evacuation scenarios,which does not meet the current standard requirements and codes.By changing the number of passengers and the number of stairs for evacuation,the flow rate capacity and evacuation time were explored,which have reference values for safety management and emergency evacuation plan optimization during peak hours of subway operation.展开更多
It is expected that multiple virtual power plants(multi-VPPs)will join and participate in the future local energy market(LEM).The trading behaviors of these VPPs needs to be carefully studied in order to maximize the ...It is expected that multiple virtual power plants(multi-VPPs)will join and participate in the future local energy market(LEM).The trading behaviors of these VPPs needs to be carefully studied in order to maximize the benefits brought to the local energy market operator(LEMO)and each VPP.We propose a bounded rationality-based trading model of multiVPPs in the local energy market by using a dynamic game approach with different trading targets.Three types of power bidding models for VPPs are first set up with different trading targets.In the dynamic game process,VPPs can also improve the degree of rationality and then find the most suitable target for different requirements by evolutionary learning after considering the opponents’bidding strategies and its own clustered resources.LEMO would decide the electricity buying/selling price in the LEM.Furthermore,the proposed dynamic game model is solved by a hybrid method consisting of an improved particle swarm optimization(IPSO)algorithm and conventional largescale optimization.Finally,case studies are conducted to show the performance of the proposed model and solution approach,which may provide some insights for VPPs to participate in the LEM in real-world complex scenarios.展开更多
CO_(2)electroreduction has been regarded as an appealing strategy for renewable energy storage.Recently,bismuth(Bi)electrocatalysts have attracted much attention due to their excellent formate selectivity.However,many...CO_(2)electroreduction has been regarded as an appealing strategy for renewable energy storage.Recently,bismuth(Bi)electrocatalysts have attracted much attention due to their excellent formate selectivity.However,many reported Bi electrocatalysts suffer from low current densities,which are insufficient for industrial applications.To reach the goal of high current CO_(2)reduction to formate,we fabricate Bi nanosheets(NS)with high activity through edge/terrace control and defect engineering strategy.Bi NS with preferential exposure sites are obtained by topotactic transformation,and the processes are clearly monitored by in-situ Raman and ex-situ X-ray diffraction(XRD).Bi NS-1 with a high fraction of edge sites and defect sites exhibits excellent performance,and the current density is up to ca.870 mA·cm^(−2)in the flow cell,far above the industrially applicable level(100 mA·cm^(−2)),with a formate Faradaic efficiency greater than 90%.In-situ Fourier transform infrared(FT-IR)spectra detect*OCHO,and theoretical calculations reveal that the formation energy of*OCHO on edges is lower than that on terraces,while the defects on edges further reduce the free energy changes(ΔG).The differential charge density spatial distributions reveal that the presence of defects on edges causes charge enrichment around the C–H bond,benefiting the stabilization of the*OCHO intermediate,thus remarkably lowering theΔG.展开更多
As an integrated carrier of energy production,transmission,distribution,conversion,storage,and utilization,multiple energy systems(MESs)have significant low-carbon potential.This paper proposes a hierarchical distribu...As an integrated carrier of energy production,transmission,distribution,conversion,storage,and utilization,multiple energy systems(MESs)have significant low-carbon potential.This paper proposes a hierarchical distributed dispatch model of MESs considering carbon trading,which is composed of the lower autonomous operation level of each MES and the upper coordinated control level.Different carbon emission sources are considered,including combined heat and power(CHP)units,gas boilers,and power to gas(P2G)devices.The transactive control(TC)mechanism is used to solve the model by introducing a virtual price signal.In the case study based on a 3-MES system,the effectiveness of the proposed distributed method is proved by comparison with a centralized algorithm.Meanwhile,the impacts of different carbon prices on MESs with different resource endowments are analyzed from the aspects of scheduling results,carbon emissions,clean energy consumption rate,and comprehensive operating costs.展开更多
The squelch problem of ultra-short wave communication under non-stationary noise and low Signal-to-Noise Ratio(SNR)in a complex electromagnetic environment is still challenging.To alleviate the problem,we proposed a s...The squelch problem of ultra-short wave communication under non-stationary noise and low Signal-to-Noise Ratio(SNR)in a complex electromagnetic environment is still challenging.To alleviate the problem,we proposed a squelch algorithm for ultra-short wave communication based on a deep neural network and the traditional energy decision method.The proposed algorithm first predicts the speech existence probability using a three-layer Gated Recurrent Unit(GRU)with the speech banding spectrum as the feature.Then it gets the final squelch result by combining the strength of the signal energy and the speech existence probability.Multiple simulations and experiments are done to verify the robustness and effectiveness of the proposed algorithm.We simulate the algorithm in three situations:the typical Amplitude Modulation(AM)and Frequency Modulation(FM)in the ultra-short wave communication under different SNR environments,the non-stationary burst-like noise environments,and the real received signal of the ultra-short wave radio.The experimental results show that the proposed algorithm performs better than the traditional squelch methods in all the simulations and experiments.In particular,the false alarm rate of the proposed squelch algorithm for non-stationary burst-like noise is significantly lower than that of traditional squelch methods.展开更多
Precise measurement of two-neutrino double beta decay(DBD)half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay.We report the measurement of DBD half-life of 136xe u...Precise measurement of two-neutrino double beta decay(DBD)half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay.We report the measurement of DBD half-life of 136xe using the Pandax-4T dual-phase Time Projection Chamber(TPC)with 3.7-tonne natural xenon and the first 94.9-day physics data release.展开更多
This paper investigated the fire-retardant mechanism of the nano-LDHs in the intumescent system by the temperature programmed oxidation (TPO). Researches were also conducted to explore the function of the nano-LDHs in...This paper investigated the fire-retardant mechanism of the nano-LDHs in the intumescent system by the temperature programmed oxidation (TPO). Researches were also conducted to explore the function of the nano-LDHs in the composite fire-retardant agents in air and nitrogen atmosphere, respectively. The results indicated that the nano-LDHs species were responsible for the catalytic oxidation of the rich-carbon compound in oxygen atmosphere. In addition, the nano-LDHs species and their calcinated products at high temperature could increase the carbonaceous residue-shield of the carbon-rich materials, improve the quality and the graphitization degree of the formed char-layer, and accelerate the intumescence and expansion of the melting carbon-rich materials to a certain degree under the oxygen-free condition, leading to the carbonization and expansion of the intumescent layer.展开更多
The change of customer behaviors and the fluctuation of spot prices can affect the benefits of electricity retailers.To address this issue,an incentive-based demand response(DR)model involving the utility and elastici...The change of customer behaviors and the fluctuation of spot prices can affect the benefits of electricity retailers.To address this issue,an incentive-based demand response(DR)model involving the utility and elasticity of customers is proposed for maximizing the benefits of retailers.The benefits will increase by triggering an incentive price to influence customer behaviors to change their demand consumptions.The optimal reduction of customers is obtained by their own profit optimization model with a certain incentive price.Then,the sensitivity of incentive price on retailers’benefits is analyzed and the optimal incentive price is obtained according to the DR model.The case study verifies the effectiveness of the proposed model.展开更多
In this paper,the influence of different opening ratios and different opening directions of the windows on the natural smoke exhaust was studied through a series of real fire experiments and simulation analysis.Increa...In this paper,the influence of different opening ratios and different opening directions of the windows on the natural smoke exhaust was studied through a series of real fire experiments and simulation analysis.Increasing the open area of the window could effectively improve the overall smoke exhaust effect.When the top windows were open and the opening ratio increased from 19.2%to 24.3%,the optical density was decreased by 12.4%.The average smoke exhaust rate per unit area of the window did not change significantly.Increasing the area of the natural smoke exhaust window could effectively increase the smoke exhaust rate and improve the overall effect of smoke extraction.When the top windows were open,the temperature rise on the top floor was 30.8%-47.5%lower while the visibility was 16.8%-21.9%higher than that when the side windows were open.展开更多
This paper proposes an impact-increment-based hybrid(IIHybrid)reliability assessment approach for power transmission systems.The proposed approach integrates the advantages of the impact-increment-based state enumerat...This paper proposes an impact-increment-based hybrid(IIHybrid)reliability assessment approach for power transmission systems.The proposed approach integrates the advantages of the impact-increment-based state enumeration method(IISE)and impact-increment-based Monte Carlo simulation(IIMC)to improve computational efficiency and accuracy.The IISE can efficiently assess the impacts of low-order contingencies.The accuracy is,however,sacrificed as highorder contingencies are usually neglected.The IIMC is more suitable for large-scale contingency spaces compared with IISE,although the calculation process is time-consuming.In this paper,the proposed IIHybrid takes advantage of its strengths while avoiding its shortcomings.The IISE and the IIMC are applied to lower and higher contingency spaces respectively.The high-order contingencies elimination technique proposed in our previous studies is still applicable to the IIHybrid.In addition,efficiency can be controlled by modifying the preset parameters to adapt to various scenarios.Case studies are performed on the IEEE 118-bus test system and PEGASE System.The results show that the proposed approach is more efficient and practicable than traditional methods.展开更多
基金supported and funded by the National Natural Science Foundation of China(General Program) (Grant NO. 41071350)the Chinese Academy of Sciences Important Directional Knowledge Innovation Project (Grant NO. KZCX2-EW-317)the Chinese Academy of Sciences Western Light Project (Grant NO.09R2340340)
文摘In this study,the current situation of pluriactivity in mountainous and hilly rural areas of Sichuan province was analyzed using representative sample survey data and natural factor data calculated based on 30 m-resolution DEM and GIS.Moreover,using logistic regression model,a quantitative analysis was conducted on factors influencing pluriactivity in terms of individuals,households,communities and natural environmental conditions.The results showed that,(1) only 17.77% of rural laborers in mountainous and hilly areas of Sichuan province were engaged in pluriactivity.Geographically,pluriactivity was mainly chosen according to the "proximity principle",and was concentrated in construction and service industries;(2) the following factors have a significant influence on whether rural laborers in hilly areas engage in pluriactivity:gender,number of years of education,marriage,number of laborers and time to towns.Those with little influence include:age,health,family size,arable land per capita and per capita income,whether there are elderly people over 75 years and children less than 3 years.According to the main factors affecting pluriactivity,the government should enhance vocational skills training for rural laborers in mountainous and hilly areas,especially for female laborers,further improve transport accessibility and encourage rural laborers,especially female laborers to move into pluriactivity to increase the income of farm households.
基金Thisworkwas supported by State Grid Science and TechnologyResearch Program(SGSCJY00NYJS2200026).
文摘The power grid operation process is complex,and many operation process data involve national security,business secrets,and user privacy.Meanwhile,labeled datasets may exist in many different operation platforms,but they cannot be directly shared since power grid data is highly privacysensitive.How to use these multi-source heterogeneous data as much as possible to build a power grid knowledge map under the premise of protecting privacy security has become an urgent problem in developing smart grid.Therefore,this paper proposes federated learning named entity recognition method for the power grid field,aiming to solve the problem of building a named entity recognition model covering the entire power grid process training by data with different security requirements.We decompose the named entity recognition(NER)model FLAT(Chinese NER Using Flat-Lattice Transformer)in each platform into a global part and a local part.The local part is used to capture the characteristics of the local data in each platform and is updated using locally labeled data.The global part is learned across different operation platforms to capture the shared NER knowledge.Its local gradients fromdifferent platforms are aggregated to update the global model,which is further delivered to each platform to update their global part.Experiments on two publicly available Chinese datasets and one power grid dataset validate the effectiveness of our method.
基金the Science and Technology Foundation of Sichuan Department of Land and Resources(SCDLR0609)
文摘By using site observation data and establishing 3D model using ANSYS software, this paper has discussed the strain change of stratum stress during process of jacking-in and the impact of machine head on ground surface under different frontal resistances. Analysis of the two cases shows that soil pressure reaches its maximum point when the soil is right above machine head, and soil stress will gradually decline when machine head passes over it. It also shows that impact brought by pipe-jacking construction on stress change of the surrounding soil is limited. The thesis suggest that road surface should be consolidated and soil condition be improved before construction to prevent loss and disaster caused by road surface deformation, jacking force can be increased so that jacking efficiency can be enhanced when ground stratum is well filled with soil, but the frontal resistance facing machine head should be equal to surrounding soil pressure in order to avoid rise of ground surface.
基金financially supported by the National Natural Science Foundation of China (41630858)
文摘Collapsing gully erosion is a specific form of soil erosion types in the hilly granitic region of tropical and subtropical South China, and can result in extremely rapid water and soil loss. Knowledge of the soil physical and chemical properties of farmland influenced by collapsing gully erosion is important in understanding the development of soil quality. This study was conducted at the Wuli Watershed of the Tongcheng County, south of Hubei Province, China. The aim is to investigate soil physical and chemical properties of three soil layers (0-20, 20-40 and 40-60 cm) for two farmland types (paddy field and upland field) in three regions influenced by collapsing gully erosion. The three regions are described as follows: strongly influenced region (SIR), weakly influenced region (WIR) and non-influenced region (NIR). The results show that collapsing gully erosion significantly increased the soil gravel and sand content in paddy and upland fields, especially the surface soil in the SIR and WIR. In the 0-20 cm layer of the paddy field, the highest gravel content (250.94 g kg-1) was in the SIR and the lowest (78.67 g kg-1) was in the NIR, but in the upland filed, the surface soil (0-20 cm) of the SIR and the 40-60 cm soil layer for the NIR had the highest (177.13 g kg-1) and the lowest (59.96 g kg-1) values of gravel content, respectively. The distribution of gravel and sand decreased with depth in the three influenced regions, but silt and clay showed the inverse change. In the paddy field, the average of sand content decreased from 58.6 (in the SIR) to 49.0% (in the NIR), but the silt content was in a reverse order, increasing from 27.9 to 36.9%, and the average of the clay content of three regions showed no significant variation (P〈0.05). But in the upland filed, the sand, silt and clay fluctuated in the NIR and the WIR. Soils in the paddy and upland field were highly acidic (pH〈5.2) in the SIR and WIR; moreover lower nutrient contents (soil organic matter (SOM), total N and available N, P, K) existed in the SIR. In the 0-20 cm soil layer of the paddy field, compared with the NIR and the WIR, collapsing gully erosion caused a very sharp decrease in the SOM and total N of the SIR (5.23 and 0.56 g kg-1, respectively). But in the surface soil (0-20 cm) of the upland field, the highest SOM, total N, available N, available P and available K occurred in the NIR, and the lowest ones were in the SIR. Compared with the NIR, the cation exchange capacity (CEC) in the SIR and WIR was found to be relatively lower. These results suggest that collapsing gully erosion seriously affect the soil physical and chemical properties of farmland, lead to coarse particles accumulation in the field and decrease pH and nutrient levels.
文摘In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–1(24.2 ton·day),and Run 11–2(37.1 ton·day).The mistake is due to an incorrect application of a small energy non-linearity(known as the BLS non-linearity)in making plots,but has no impact to the final results.Figures 2 and 3 are now updated in this note.
基金financial support from the National Natural Science Foundation of China (21938005, 21573147, 22005190, 22008154, 21872163)the Science & Technology Commission of Shanghai Municipality, the Natural Science Foundation of Shanghai (19DZ1205500, 19ZR1424600, 19ZR1475100)the Sichuan Science and Technology Program (2021JDRC0015 to L.S.L)。
文摘P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversible lattice oxygen release. Here we systematically investigated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hindered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.
文摘Global opinion on and perception of Tibetan attitudes and affairs have been heavily shaped by one group of Tibetans,namely the Dalai Lama and his fellow exiles.They have done so on the claim that they speak for all sixplus million Tibetans,overseas as well as in China.On this claim they also seek autonomy of a so-called Greater Tibet from Beijing,which is the
基金Supported in part by the National Key R&D Program of China(Grant No.2016YFA0400301)the National Natural Science Foundation of China(Grant Nos.11525522,11775141,and 11755001)+5 种基金the Double First Class Plan of the Shanghai Jiao Tong University,the China Postdoctoral Science Foundation(Grant No.2018M640036)the Office of Science and Technology,Shanghai Municipal Government(Grant Nos.11DZ2260700,16DZ2260200,and 18JC1410200)the Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Education,for important supportsponsorship from the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)the Hongwen Foundation in Hong Kongthe Tencent Foundation in China。
文摘We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total exposure of 100.7 ton·day with liquid xenon.With robust estimates of the dominant background spectra,we perform sensitive searches on solar axions and neutrinos with enhanced magnetic moment.It is found that the axionelectron coupling gAe<4.6×10^(-12) for an axion mass less than 0.1 keV/c^(2) and the neutrino magnetic moment μv<4.9×10^(-11)μB at 90%confidence level.The observed excess from XENON1 T is within our experimental constraints.
基金This study has been sponsored by the Fire Bureau of the Ministry of Public Security(Grant No.2016XFGG05)the Sichuan Mineral Resources Research Center(Grant No.SCKCZY2022-YB010)the Key Laboratory of Flight Techniques and Flight Safety,CAAC(Grant No.FZ2021KF05).
文摘Because of its large capacity,high efficiency and energy savings,the subway has gradually become the primary mode of transportation for citizens.A high density of passengers exists within a large-passenger-flow subway station,and the number of casualties and injuries during a fire emergency is substantial.In this paper,Pathfinder software and on-site measured data of Pingzhou station in Shenzhen(China)were utilized to simulate a fire emergency evacuation in a large-passenger-flow subway station.The Required Safe Egress Time(RSET),number of passengers and flow rates of stairs and escalators were analysed for three fire evacuation scenarios:train fire,platform fire and hall fire.The evacuation time of the train fire,which was 1173 s,was the longest,and 3621 occupants needed to evacuate when the train was fully loaded.Occupants could not complete the evacuation within 6 mins in all three fire evacuation scenarios,which does not meet the current standard requirements and codes.By changing the number of passengers and the number of stairs for evacuation,the flow rate capacity and evacuation time were explored,which have reference values for safety management and emergency evacuation plan optimization during peak hours of subway operation.
基金This work was supported by the National Key R&D Program of China(Grant No.2019YFE0123600)National Science Foundation of China(Grant No.52077146)Young Elite Scientists Sponsorship Program by CSEE(Grant No.CESS-YESS-2019027).
文摘It is expected that multiple virtual power plants(multi-VPPs)will join and participate in the future local energy market(LEM).The trading behaviors of these VPPs needs to be carefully studied in order to maximize the benefits brought to the local energy market operator(LEMO)and each VPP.We propose a bounded rationality-based trading model of multiVPPs in the local energy market by using a dynamic game approach with different trading targets.Three types of power bidding models for VPPs are first set up with different trading targets.In the dynamic game process,VPPs can also improve the degree of rationality and then find the most suitable target for different requirements by evolutionary learning after considering the opponents’bidding strategies and its own clustered resources.LEMO would decide the electricity buying/selling price in the LEM.Furthermore,the proposed dynamic game model is solved by a hybrid method consisting of an improved particle swarm optimization(IPSO)algorithm and conventional largescale optimization.Finally,case studies are conducted to show the performance of the proposed model and solution approach,which may provide some insights for VPPs to participate in the LEM in real-world complex scenarios.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.22105133 and 22101191)China Postdoctoral Science Foundation(Nos.BX20190222,2019M663490,and 2021M692261)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.20826041E4211,20826041E4258,20826041E4212,2021SCU12150 and 2021SCU12151)the China Scholarship Council,and Sichuan Science and Technology Program(No.2021YJ0405).
文摘CO_(2)electroreduction has been regarded as an appealing strategy for renewable energy storage.Recently,bismuth(Bi)electrocatalysts have attracted much attention due to their excellent formate selectivity.However,many reported Bi electrocatalysts suffer from low current densities,which are insufficient for industrial applications.To reach the goal of high current CO_(2)reduction to formate,we fabricate Bi nanosheets(NS)with high activity through edge/terrace control and defect engineering strategy.Bi NS with preferential exposure sites are obtained by topotactic transformation,and the processes are clearly monitored by in-situ Raman and ex-situ X-ray diffraction(XRD).Bi NS-1 with a high fraction of edge sites and defect sites exhibits excellent performance,and the current density is up to ca.870 mA·cm^(−2)in the flow cell,far above the industrially applicable level(100 mA·cm^(−2)),with a formate Faradaic efficiency greater than 90%.In-situ Fourier transform infrared(FT-IR)spectra detect*OCHO,and theoretical calculations reveal that the formation energy of*OCHO on edges is lower than that on terraces,while the defects on edges further reduce the free energy changes(ΔG).The differential charge density spatial distributions reveal that the presence of defects on edges causes charge enrichment around the C–H bond,benefiting the stabilization of the*OCHO intermediate,thus remarkably lowering theΔG.
基金supported by the National Natural Science Foundation of China (U2166211).
文摘As an integrated carrier of energy production,transmission,distribution,conversion,storage,and utilization,multiple energy systems(MESs)have significant low-carbon potential.This paper proposes a hierarchical distributed dispatch model of MESs considering carbon trading,which is composed of the lower autonomous operation level of each MES and the upper coordinated control level.Different carbon emission sources are considered,including combined heat and power(CHP)units,gas boilers,and power to gas(P2G)devices.The transactive control(TC)mechanism is used to solve the model by introducing a virtual price signal.In the case study based on a 3-MES system,the effectiveness of the proposed distributed method is proved by comparison with a centralized algorithm.Meanwhile,the impacts of different carbon prices on MESs with different resource endowments are analyzed from the aspects of scheduling results,carbon emissions,clean energy consumption rate,and comprehensive operating costs.
文摘The squelch problem of ultra-short wave communication under non-stationary noise and low Signal-to-Noise Ratio(SNR)in a complex electromagnetic environment is still challenging.To alleviate the problem,we proposed a squelch algorithm for ultra-short wave communication based on a deep neural network and the traditional energy decision method.The proposed algorithm first predicts the speech existence probability using a three-layer Gated Recurrent Unit(GRU)with the speech banding spectrum as the feature.Then it gets the final squelch result by combining the strength of the signal energy and the speech existence probability.Multiple simulations and experiments are done to verify the robustness and effectiveness of the proposed algorithm.We simulate the algorithm in three situations:the typical Amplitude Modulation(AM)and Frequency Modulation(FM)in the ultra-short wave communication under different SNR environments,the non-stationary burst-like noise environments,and the real received signal of the ultra-short wave radio.The experimental results show that the proposed algorithm performs better than the traditional squelch methods in all the simulations and experiments.In particular,the false alarm rate of the proposed squelch algorithm for non-stationary burst-like noise is significantly lower than that of traditional squelch methods.
基金This project is supported in part by grants from the Ministry of Science and Technology of China(No.2016YFA0400301 and 2016YFA0400302)grants from National Science Foundation of China(Nos.12090061,12090062,12005131,11905128,and 11925502)by Office of Science and Technology,Shanghai Municipal Government(grant No.18JC1410200).
文摘Precise measurement of two-neutrino double beta decay(DBD)half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay.We report the measurement of DBD half-life of 136xe using the Pandax-4T dual-phase Time Projection Chamber(TPC)with 3.7-tonne natural xenon and the first 94.9-day physics data release.
基金Supported by the Social Public Benefit Research Special Funds of Scientific Research Institute of China (Grant No. 2005DIA2J007)the Applying Innovation Plan Funds of Ministry of Public Security of China (Grant No. 2005YYCXSCXF008)
文摘This paper investigated the fire-retardant mechanism of the nano-LDHs in the intumescent system by the temperature programmed oxidation (TPO). Researches were also conducted to explore the function of the nano-LDHs in the composite fire-retardant agents in air and nitrogen atmosphere, respectively. The results indicated that the nano-LDHs species were responsible for the catalytic oxidation of the rich-carbon compound in oxygen atmosphere. In addition, the nano-LDHs species and their calcinated products at high temperature could increase the carbonaceous residue-shield of the carbon-rich materials, improve the quality and the graphitization degree of the formed char-layer, and accelerate the intumescence and expansion of the melting carbon-rich materials to a certain degree under the oxygen-free condition, leading to the carbonization and expansion of the intumescent layer.
基金supported in part by the National Natural Science Foundation of China(No.51807127)in part by the Fundamental Research Funds for the Central Universities of China opment Program of China(No.2018YFB0905200).(No.YJ201654)in part by the National Key Research and Development Program of China(No.2018YFB0905200).
文摘The change of customer behaviors and the fluctuation of spot prices can affect the benefits of electricity retailers.To address this issue,an incentive-based demand response(DR)model involving the utility and elasticity of customers is proposed for maximizing the benefits of retailers.The benefits will increase by triggering an incentive price to influence customer behaviors to change their demand consumptions.The optimal reduction of customers is obtained by their own profit optimization model with a certain incentive price.Then,the sensitivity of incentive price on retailers’benefits is analyzed and the optimal incentive price is obtained according to the DR model.The case study verifies the effectiveness of the proposed model.
基金This work was supported by SCFRI research project(No.T2019881101,No.T2019880402).
文摘In this paper,the influence of different opening ratios and different opening directions of the windows on the natural smoke exhaust was studied through a series of real fire experiments and simulation analysis.Increasing the open area of the window could effectively improve the overall smoke exhaust effect.When the top windows were open and the opening ratio increased from 19.2%to 24.3%,the optical density was decreased by 12.4%.The average smoke exhaust rate per unit area of the window did not change significantly.Increasing the area of the natural smoke exhaust window could effectively increase the smoke exhaust rate and improve the overall effect of smoke extraction.When the top windows were open,the temperature rise on the top floor was 30.8%-47.5%lower while the visibility was 16.8%-21.9%higher than that when the side windows were open.
基金This work was supported in part by the Youth Program of National Natural Science Foundation of China(No.52077150)in part by the Ministry of Education of China(No.20XJC630009).
文摘This paper proposes an impact-increment-based hybrid(IIHybrid)reliability assessment approach for power transmission systems.The proposed approach integrates the advantages of the impact-increment-based state enumeration method(IISE)and impact-increment-based Monte Carlo simulation(IIMC)to improve computational efficiency and accuracy.The IISE can efficiently assess the impacts of low-order contingencies.The accuracy is,however,sacrificed as highorder contingencies are usually neglected.The IIMC is more suitable for large-scale contingency spaces compared with IISE,although the calculation process is time-consuming.In this paper,the proposed IIHybrid takes advantage of its strengths while avoiding its shortcomings.The IISE and the IIMC are applied to lower and higher contingency spaces respectively.The high-order contingencies elimination technique proposed in our previous studies is still applicable to the IIHybrid.In addition,efficiency can be controlled by modifying the preset parameters to adapt to various scenarios.Case studies are performed on the IEEE 118-bus test system and PEGASE System.The results show that the proposed approach is more efficient and practicable than traditional methods.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(Grant No.91941301)the Key Research and Development Project of Sichuan Province(Grant No.2019ZYZF0002)。