Nanocomposites composed of one-dimensional（1D） CdS nanowires（NWs） and 1 T-MoS2 nanosheets have been fabricated through a two-step solvothermal process. 5 mol% of MoS2 loading results in the best optical properties...Nanocomposites composed of one-dimensional（1D） CdS nanowires（NWs） and 1 T-MoS2 nanosheets have been fabricated through a two-step solvothermal process. 5 mol% of MoS2 loading results in the best optical properties,photoelectrochemical（PEC） as well as photocatalytic activities for hydrogen evolution reaction（HER）. Compared with pure CdS NWs, the optimized nanocomposite shows 5.5 times enhancement in photocurrent and 86.3 times increase for HER in the presence of glucose and lactic acid as hole scavengers.The enhanced PEC and HER activities are attributed to the intimate contact between MoS2 and CdS that efficiently enhances charge carrier separation. In addition, ultrafast transient absorption（TA） measurements have been used to probe the charge carrier dynamics and gain deeper insight into the mechanism behind the enhanced PEC and photocatalytic performance.展开更多
Cutting MXene to a minimum size and forming the derived two-dimensional MXene quantum dots(MQDs),which possess a unique intrinsic layered geometry structure,restricts exciton due to their novel spatial dimension.This ...Cutting MXene to a minimum size and forming the derived two-dimensional MXene quantum dots(MQDs),which possess a unique intrinsic layered geometry structure,restricts exciton due to their novel spatial dimension.This gives rise to a broad spectrum of fascinating properties,rendering them for various applications.Herewith,the correlation between composition,structure,and processing control of MQDs is investigated systematically,giving further insight into the intrinsic and extrinsic properties.This review also provides an opportunity to explore new compositions,modify the properties,and tailor MQDs into the guided architectural design before any prospective applications.展开更多
Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a ...Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a sealant,coupled with an air seepage evaluation model that incorporates Knudsen diffusion.Moreover,the initial coating application methods were outlined,and the advantages of using NOSP compared to other sealing materials,particularly regarding cost and construction techniques,were also examined and discussed.Experimental results indicated a significant reduction in permeability of rock specimens coated with a 7–10μm thick NOSP layer.Specifically,under a 0.5 MPa pulse pressure,the permeability decreased to less than 1 n D,and under a 4 MPa pulse pressure,it ranged between4.5×10^(-6)–5.5×10^(-6)m D,marking a 75%–80%decrease in granite permeability.The sealing efficacy of NOSP surpasses concrete and is comparable to rubber materials.The optimal viscosity for application lies between 95 and 105 KU,and the coating thickness should ideally range from 7 to 10μm,applied to substrates with less than 3%porosity.This study provides new insights into air transport and sealing mechanisms at the pore level,proposing NOSP as a cost-effective and simplified solution for CAES applications.展开更多
Karst fracture-cavity carbonate reservoirs,in which natural cavities are connected by natural fractures to form cavity clusters in many circumstances,have become significant fields of oil and gas exploration and explo...Karst fracture-cavity carbonate reservoirs,in which natural cavities are connected by natural fractures to form cavity clusters in many circumstances,have become significant fields of oil and gas exploration and exploitation.Proppant fracturing is considered as the best method for exploiting carbonate reservoirs;however,previous studies primarily focused on the effects of individual types of geological formations,such as natural fractures or cavities,on fracture propagation.In this study,true-triaxial physical simulation experiments were systematically performed under four types of stress difference conditions after the accurate prefabrication of four types of different fracture-cavity distributions in artificial samples.Subsequently,the interaction mechanism between the hydraulic fractures and fracture-cavity structures was systematically analyzed in combination with the stress distribution,cross-sectional morphology of the main propagation path,and three-dimensional visualization of the overall fracture network.It was found that the propagation of hydraulic fractures near the cavity was inhibited by the stress concentration surrounding the cavity.In contrast,a natural fracture with a smaller approach angle(0°and 30°)around the cavity can alleviate the stress concentration and significantly facilitate the connection with the cavity.In addition,the hydraulic fracture crossed the natural fracture at the 45°approach angle and bypassed the cavity under higher stress difference conditions.A new stimulation effectiveness evaluation index was established based on the stimulated reservoir area(SRA),tortuosity of the hydraulic fractures(T),and connectivity index(CI)of the cavities.These findings provide new insights into the fracturing design of carbonate reservoirs.展开更多
Ag-TiO2/ITO film electrode was used as photoanode to investigate the feasibility of a hybrid technology of Ag nanoparticles combined with the application of anodic bias. The results showed that the deposited Ag and a...Ag-TiO2/ITO film electrode was used as photoanode to investigate the feasibility of a hybrid technology of Ag nanoparticles combined with the application of anodic bias. The results showed that the deposited Ag and applied anodic bias have an apparent additive effect.展开更多
1.Introduction Promoting the green and low-carbon transition of energy systems and constructing a new renewable-dominated power system is essential to achieving carbon neutrality in China[1,2].Furthermore,implementing...1.Introduction Promoting the green and low-carbon transition of energy systems and constructing a new renewable-dominated power system is essential to achieving carbon neutrality in China[1,2].Furthermore,implementing electrification and hydrogenation strategies to address energy consumption is necessary for a successful energy transition.China’s share of electricity in its total energy consumption is estimated to increase from 26%in 2021 to more than 70%by 2060.展开更多
Increasing the allowable gas pressure of underground gas storage(UGS) is one of the most effective methods to increase its working gas capacity. In this context, hydraulic fracturing tests are implemented on the targe...Increasing the allowable gas pressure of underground gas storage(UGS) is one of the most effective methods to increase its working gas capacity. In this context, hydraulic fracturing tests are implemented on the target formation for the UGS construction of Jintan salt caverns, China, in order to obtain the minimum principal in situ stress and the fracture breakdown pressure. Based on the test results, the maximum allowable gas pressure of the Jintan UGS salt cavern is calibrated. To determine the maximum allowable gas pressure, KING-1 and KING-2 caverns are used as examples. A three-dimensional(3D)geomechanical model is established based on the sonar data of the two caverns with respect to the features of the target formation. New criteria for evaluating gas penetration failure and gas seepage are proposed. Results show that the maximum allowable gas pressure of the Jintan UGS salt cavern can be increased from 17 MPa to 18 MPa(i.e. a gradient of about 18 k Pa/m at the casing shoe depth). Based on numerical results, a field test with increasing maximum gas pressure to 18 MPa has been carried out in KING-1 cavern. Microseismic monitoring has been conducted during the test to evaluate the safety of the rock mass around the cavern. Field monitoring data show that KING-1 cavern is safe globally when the maximum gas pressure is increased from 17 MPa to 18 MPa. This shows that the geomechanical model and criteria proposed in this context for evaluating the maximum allowable gas pressure are reliable.展开更多
Network intrusion poses a severe threat to the Internet.However,existing intrusion detection models cannot effectively distinguish different intrusions with high-degree feature overlap.In addition,efficient real-time ...Network intrusion poses a severe threat to the Internet.However,existing intrusion detection models cannot effectively distinguish different intrusions with high-degree feature overlap.In addition,efficient real-time detection is an urgent problem.To address the two above problems,we propose a Latent Dirichlet Allocation topic model-based framework for real-time network Intrusion Detection(LDA-ID),consisting of static and online LDA-ID.The problem of feature overlap is transformed into static LDA-ID topic number optimization and topic selection.Thus,the detection is based on the latent topic features.To achieve efficient real-time detection,we design an online computing mode for static LDA-ID,in which a parameter iteration method based on momentum is proposed to balance the contribution of prior knowledge and new information.Furthermore,we design two matching mechanisms to accommodate the static and online LDA-ID,respectively.Experimental results on the public NSL-KDD and UNSW-NB15 datasets show that our framework gets higher accuracy than the others.展开更多
PHOTOSYSTEM Ⅱ（PS Ⅱ） particles capable of O<sub>2</sub> evolution contain D1, D2 transmembrane pro-teins, and three extrinsic polypeptides which are exposed to the outer aqueous phase with ap-parent mol...PHOTOSYSTEM Ⅱ（PS Ⅱ） particles capable of O<sub>2</sub> evolution contain D1, D2 transmembrane pro-teins, and three extrinsic polypeptides which are exposed to the outer aqueous phase with ap-parent molecular masses of 33, 23, 18 kD. The three proteins can be partially or totally re-moved by treating the PS Ⅱ membranes with high concentrations of salt or other methods,展开更多
1.Definition of deep underground energy storage Deep underground energy storage(DUES)is an important strategic practice for ensuring China’s energy supply,its national defense,and the realization of China’s strategi...1.Definition of deep underground energy storage Deep underground energy storage(DUES)is an important strategic practice for ensuring China’s energy supply,its national defense,and the realization of China’s strategic goals of achieving a carbon peak and carbon neutrality(CPCN).In 2021,China’s oil and natural gas consumption reached 712 million tonnes and 372.6 billion cubic meters,respectively,while its external dependence reached about 72%and 45%.China’s reserves only met about 30%of the requirements for a safe supply and peak shaving.展开更多
As typical quarternary copper-based chalcogenides,Cu–Zn–Sn–S nanocrystals(CZTS NCs)have emerged as a newfashioned electrocatalyst in hydrogen evolution reactions(HERs).Oleylamine(OM),a reducing surfactant and solve...As typical quarternary copper-based chalcogenides,Cu–Zn–Sn–S nanocrystals(CZTS NCs)have emerged as a newfashioned electrocatalyst in hydrogen evolution reactions(HERs).Oleylamine(OM),a reducing surfactant and solvent,plays a significant role in the assisting synthesis of CZTS NCs due to the ligand effect.Herein,we adopted a facile one-pot colloidal method for achieving the structure evolution of CZTS NCs from 2D nanosheets to 1D nanorods assisted through the continuous addition of OM.During the process,the mechanism of OM-induced morphology evolution was further discussed.When merely adding pure 1-dodecanethiol(DDT)as the solvent,the CZTS nanosheets were obtained.As OM was gradually added to the reaction,the CZTS NCs began to grow along the sides of the nanosheets and gradually shrink at the top,followed by the formation of stable nanorods.In acidic electrolytic conditions,the CZTS NCs with 1.0 OM addition display the optimal HER activity with a low overpotential of 561 m V at 10 m A/cm^(2) and a small Tafel slope of 157.6 m V/dec compared with other CZTS samples.The enhancement of HER activity could be attributed to the contribution of the synergistic effect of the diverse crystal facets to the reaction.展开更多
Based on the analysis of the deformation in an infinite isotropic elastic matrix with an embedded elliptic crack under far field coupled tensile and shear stresses, the energy release rate and a mixed fracture criteri...Based on the analysis of the deformation in an infinite isotropic elastic matrix with an embedded elliptic crack under far field coupled tensile and shear stresses, the energy release rate and a mixed fracture criterion are obtained using an energy balance approach. The additional compliance tensor induced by a single opening elliptic microcrack in a representative volume element is derived, and the effect of microcracks with random orientations is analyzed with the Taylor＇s scheme by introducing an appropriate probability density function. A micromechanical damage model for rocks and concretes is obtained and is verified with experimental results.展开更多
Effects of Photosystem Ⅱ (PS Ⅱ) extrinsic polypeptides of oxygen-evolving complex and manganese clusters on PS Ⅱ carbonic anhydrase (CA) were studied with spinach PS Ⅱ membranes. The result supported that membrane...Effects of Photosystem Ⅱ (PS Ⅱ) extrinsic polypeptides of oxygen-evolving complex and manganese clusters on PS Ⅱ carbonic anhydrase (CA) were studied with spinach PS Ⅱ membranes. The result supported that membrane-bound CA is located in the donor side of PS Ⅱ. The extrinsic polypeptides played an important role of maintaining CA activity. After removing manganese clusters, oxygen evolution activity was inhibited, but PSⅡ-CA activity was unchanged. It was concluded that CA activity is independent of the presence of manganese clusters, and was not directly correlated with oxygen evolution activity.展开更多
Existing almost deep learning methods rely on a large amount of annotated data, so they are inappropriate for forest fire smoke detection with limited data. In this paper, a novel hybrid attention-based few-shot learn...Existing almost deep learning methods rely on a large amount of annotated data, so they are inappropriate for forest fire smoke detection with limited data. In this paper, a novel hybrid attention-based few-shot learning method, named Attention-Based Prototypical Network, is proposed for forest fire smoke detection. Specifically, feature extraction network, which consists of convolutional block attention module, could extract high-level and discriminative features and further decrease the false alarm rate resulting from suspected smoke areas. Moreover, we design a metalearning module to alleviate the overfitting issue caused by limited smoke images, and the meta-learning network enables achieving effective detection via comparing the distance between the class prototype of support images and the features of query images. A series of experiments on forest fire smoke datasets and miniImageNet dataset testify that the proposed method is superior to state-of-the-art few-shot learning approaches.展开更多
The evolution of coronaviruses,such as SARS-CoV-2,makes broad-spectrum coronavirus preventional or therapeutical strategies highly sought after.Here we report a human angiotensin-converting enzyme 2(ACE2)-targeting mo...The evolution of coronaviruses,such as SARS-CoV-2,makes broad-spectrum coronavirus preventional or therapeutical strategies highly sought after.Here we report a human angiotensin-converting enzyme 2(ACE2)-targeting monoclonal antibody,3E8,blocked the S1-subunits and pseudo-typed virus constructs from multiple coronaviruses including SARS-CoV-2,SARS-CoV-2 mutant variants(SARS-CoV-2-D614G,B.1.1.7,B.1.351,B.1.617.1,and P.1).展开更多
Satisfiability problem of authorization require- ments in business process asks whether there exists an as- signment of users to tasks that satisfies all the requirements, and methods were proposed to solve this probl...Satisfiability problem of authorization require- ments in business process asks whether there exists an as- signment of users to tasks that satisfies all the requirements, and methods were proposed to solve this problem. However, the proposed methods are inefficient in the sense that a step of the methods is searching all the possible assignments, which is time-consuming. This work proposes a method to solve the satisfiability problem of authorization requirements with- out browsing the assignments space. Our method uses im- proved separation of duty algebra （ISoDA） to describe a sat- isfiability problem of qualification requirements and quan- tification requirements （Separation of Duty and Binding of Duty requirements）. Thereafter, ISoDA expressions are re- duced into multi-mutual-exclusive expressions. The satisfia- bilities of multi-mutual-exclusive expressions are determined by an efficient algorithm proposed in this study. The experiment shows that our method is faster than the state-of-the-art methods.展开更多
In the present paper,the analyticity of solutions to a class of degenerate elliptic equations is obtained.A kind of weighted norms are introduced and under such norms some degenerate elliptic operators are of weak coe...In the present paper,the analyticity of solutions to a class of degenerate elliptic equations is obtained.A kind of weighted norms are introduced and under such norms some degenerate elliptic operators are of weak coerciveness.展开更多
In the system of Computer Network Collaborative Defense(CNCD),it is difficult to evaluate the trustworthiness of defense agents which are newly added to the system,since they lack historical interaction for trust eval...In the system of Computer Network Collaborative Defense(CNCD),it is difficult to evaluate the trustworthiness of defense agents which are newly added to the system,since they lack historical interaction for trust evaluation.This will lead that the newly added agents could not get reasonable initial trustworthiness,and affect the whole process of trust evaluation.To solve this problem in CNCD,a trust type based trust bootstrapping model was introduced in this research.First,the division of trust type,trust utility and defense cost were discussed.Then the constraints of defense tasks were analyzed based on game theory.According to the constraints obtained,the trust type of defense agents was identified and the initial trustworthiness was assigned to defense agents.The simulated experiment shows that the methods proposed have lower failure rate of defense tasks and better adaptability in the respect of defense task execution.展开更多
A green mutant was obtained among the chemically induced mutants of Rhodobacter sphaeroides 601 (RS601) and named GM309. A blue shift of 20 nm of the carotenoid absorption spectrum was found in the light-harvesting co...A green mutant was obtained among the chemically induced mutants of Rhodobacter sphaeroides 601 (RS601) and named GM309. A blue shift of 20 nm of the carotenoid absorption spectrum was found in the light-harvesting complex II (LH2) of GM309. Different from LH2 of RS601, it was found that the carotenoids in GM309-LH2 changed to be neurosporene by mutation. Neurosporene lacks a conjugate double bond, compared with the spheroidene in RS601-LH2 which has ten conjugate double bonds. As shown by absorption and circular dichroism spectroscopy, the overall structure of GM309-LH2 is little affected by this change. From fluorescence emission spectra, it is found that GM309-LH2 can transfer energy from carotenoids to Bchl-B850 without any change in efficiency. But the efficiency of energy transfer from B800 to B850 in GM309-LH2 is decreased to be 42% of that of the native. This work would provide a novel method to investigate the mechanism of excitation energy transfer in LH2.展开更多
The solvability of a linear equation and the regularity of the solution are discussed. The equation is arising in a geometric problem which is concerned with the realization of Alexandroff's positive annul in R3.
基金financially supported by the National Natural Science Foundation of China (51402126)support from Delta Dental Health Associates, NASA through MACES (NNX15AQ01A)UCSC Committee on Research Special Research Grant
文摘Nanocomposites composed of one-dimensional（1D） CdS nanowires（NWs） and 1 T-MoS2 nanosheets have been fabricated through a two-step solvothermal process. 5 mol% of MoS2 loading results in the best optical properties,photoelectrochemical（PEC） as well as photocatalytic activities for hydrogen evolution reaction（HER）. Compared with pure CdS NWs, the optimized nanocomposite shows 5.5 times enhancement in photocurrent and 86.3 times increase for HER in the presence of glucose and lactic acid as hole scavengers.The enhanced PEC and HER activities are attributed to the intimate contact between MoS2 and CdS that efficiently enhances charge carrier separation. In addition, ultrafast transient absorption（TA） measurements have been used to probe the charge carrier dynamics and gain deeper insight into the mechanism behind the enhanced PEC and photocatalytic performance.
基金support by the Development Plan of Science and Technology of Jilin Province,China(grant No.YDZJ202301ZYTS28).
文摘Cutting MXene to a minimum size and forming the derived two-dimensional MXene quantum dots(MQDs),which possess a unique intrinsic layered geometry structure,restricts exciton due to their novel spatial dimension.This gives rise to a broad spectrum of fascinating properties,rendering them for various applications.Herewith,the correlation between composition,structure,and processing control of MQDs is investigated systematically,giving further insight into the intrinsic and extrinsic properties.This review also provides an opportunity to explore new compositions,modify the properties,and tailor MQDs into the guided architectural design before any prospective applications.
基金supported by the National Natural Science Foundation of China(No.42272321)Hubei Provincial Key Research Projects(Nos.2022BAA093 and 2022BAD163)+1 种基金Major Scientific and Technological Special Project of Jiangxi Province(No.2023ACG01004)WSGRI Engineering&Surveying Incorporation Limited(No.6120230256)。
文摘Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a sealant,coupled with an air seepage evaluation model that incorporates Knudsen diffusion.Moreover,the initial coating application methods were outlined,and the advantages of using NOSP compared to other sealing materials,particularly regarding cost and construction techniques,were also examined and discussed.Experimental results indicated a significant reduction in permeability of rock specimens coated with a 7–10μm thick NOSP layer.Specifically,under a 0.5 MPa pulse pressure,the permeability decreased to less than 1 n D,and under a 4 MPa pulse pressure,it ranged between4.5×10^(-6)–5.5×10^(-6)m D,marking a 75%–80%decrease in granite permeability.The sealing efficacy of NOSP surpasses concrete and is comparable to rubber materials.The optimal viscosity for application lies between 95 and 105 KU,and the coating thickness should ideally range from 7 to 10μm,applied to substrates with less than 3%porosity.This study provides new insights into air transport and sealing mechanisms at the pore level,proposing NOSP as a cost-effective and simplified solution for CAES applications.
基金sponsored by the National Natural Science Foundation of China(Grants Nos.52104046 and 52104010).
文摘Karst fracture-cavity carbonate reservoirs,in which natural cavities are connected by natural fractures to form cavity clusters in many circumstances,have become significant fields of oil and gas exploration and exploitation.Proppant fracturing is considered as the best method for exploiting carbonate reservoirs;however,previous studies primarily focused on the effects of individual types of geological formations,such as natural fractures or cavities,on fracture propagation.In this study,true-triaxial physical simulation experiments were systematically performed under four types of stress difference conditions after the accurate prefabrication of four types of different fracture-cavity distributions in artificial samples.Subsequently,the interaction mechanism between the hydraulic fractures and fracture-cavity structures was systematically analyzed in combination with the stress distribution,cross-sectional morphology of the main propagation path,and three-dimensional visualization of the overall fracture network.It was found that the propagation of hydraulic fractures near the cavity was inhibited by the stress concentration surrounding the cavity.In contrast,a natural fracture with a smaller approach angle(0°and 30°)around the cavity can alleviate the stress concentration and significantly facilitate the connection with the cavity.In addition,the hydraulic fracture crossed the natural fracture at the 45°approach angle and bypassed the cavity under higher stress difference conditions.A new stimulation effectiveness evaluation index was established based on the stimulated reservoir area(SRA),tortuosity of the hydraulic fractures(T),and connectivity index(CI)of the cavities.These findings provide new insights into the fracturing design of carbonate reservoirs.
基金Financial support by NNSF(20277046)NSF(990274)+1 种基金EPA(1999-14)Sci.and Technol.Proj.(A3030502)of Guangdong and The Key Lab.of Environ.Sci.Technol.of Hennan.
文摘Ag-TiO2/ITO film electrode was used as photoanode to investigate the feasibility of a hybrid technology of Ag nanoparticles combined with the application of anodic bias. The results showed that the deposited Ag and applied anodic bias have an apparent additive effect.
基金funded by the Henan Institute for Chinese Development Strategy of Engineering and Technology(2022HENZDA02)the Science and Technology Department of Sichuan Province(2021YFH0010)the High-End Foreign Experts Program of the Yunnan Revitalization Talents Support Plan of Yunnan Province。
文摘1.Introduction Promoting the green and low-carbon transition of energy systems and constructing a new renewable-dominated power system is essential to achieving carbon neutrality in China[1,2].Furthermore,implementing electrification and hydrogenation strategies to address energy consumption is necessary for a successful energy transition.China’s share of electricity in its total energy consumption is estimated to increase from 26%in 2021 to more than 70%by 2060.
基金financial supports of National Natural Science Foundation of China (Grant No. 41502296)Youth Innovation Promotion Association, Chinese Academy of Sciences (CAS) (Grant No. 2016296)+1 种基金National Natural Science Foundation of China Innovative Research Team (Grant No. 51621006)Natural Science Foundation for Innovation Group of Hubei Province, China (Grant No. 2016CFA014)
文摘Increasing the allowable gas pressure of underground gas storage(UGS) is one of the most effective methods to increase its working gas capacity. In this context, hydraulic fracturing tests are implemented on the target formation for the UGS construction of Jintan salt caverns, China, in order to obtain the minimum principal in situ stress and the fracture breakdown pressure. Based on the test results, the maximum allowable gas pressure of the Jintan UGS salt cavern is calibrated. To determine the maximum allowable gas pressure, KING-1 and KING-2 caverns are used as examples. A three-dimensional(3D)geomechanical model is established based on the sonar data of the two caverns with respect to the features of the target formation. New criteria for evaluating gas penetration failure and gas seepage are proposed. Results show that the maximum allowable gas pressure of the Jintan UGS salt cavern can be increased from 17 MPa to 18 MPa(i.e. a gradient of about 18 k Pa/m at the casing shoe depth). Based on numerical results, a field test with increasing maximum gas pressure to 18 MPa has been carried out in KING-1 cavern. Microseismic monitoring has been conducted during the test to evaluate the safety of the rock mass around the cavern. Field monitoring data show that KING-1 cavern is safe globally when the maximum gas pressure is increased from 17 MPa to 18 MPa. This shows that the geomechanical model and criteria proposed in this context for evaluating the maximum allowable gas pressure are reliable.
基金supported by the National Natural Science Foundation of China(Grant No.U1636208,No.61862008,No.61902013)the Beihang Youth Top Talent Support Program(Grant No.YWF-21-BJJ-1039)。
文摘Network intrusion poses a severe threat to the Internet.However,existing intrusion detection models cannot effectively distinguish different intrusions with high-degree feature overlap.In addition,efficient real-time detection is an urgent problem.To address the two above problems,we propose a Latent Dirichlet Allocation topic model-based framework for real-time network Intrusion Detection(LDA-ID),consisting of static and online LDA-ID.The problem of feature overlap is transformed into static LDA-ID topic number optimization and topic selection.Thus,the detection is based on the latent topic features.To achieve efficient real-time detection,we design an online computing mode for static LDA-ID,in which a parameter iteration method based on momentum is proposed to balance the contribution of prior knowledge and new information.Furthermore,we design two matching mechanisms to accommodate the static and online LDA-ID,respectively.Experimental results on the public NSL-KDD and UNSW-NB15 datasets show that our framework gets higher accuracy than the others.
文摘PHOTOSYSTEM Ⅱ（PS Ⅱ） particles capable of O<sub>2</sub> evolution contain D1, D2 transmembrane pro-teins, and three extrinsic polypeptides which are exposed to the outer aqueous phase with ap-parent molecular masses of 33, 23, 18 kD. The three proteins can be partially or totally re-moved by treating the PS Ⅱ membranes with high concentrations of salt or other methods,
基金financial support from the National Natural Science Foundation of China(42072307)Hubei Province Outstanding Youth Fund(2021CFA095)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDC10020300)。
文摘1.Definition of deep underground energy storage Deep underground energy storage(DUES)is an important strategic practice for ensuring China’s energy supply,its national defense,and the realization of China’s strategic goals of achieving a carbon peak and carbon neutrality(CPCN).In 2021,China’s oil and natural gas consumption reached 712 million tonnes and 372.6 billion cubic meters,respectively,while its external dependence reached about 72%and 45%.China’s reserves only met about 30%of the requirements for a safe supply and peak shaving.
基金partially supported by National Natural Science Foundation of China (12274021 and 62075005)。
文摘As typical quarternary copper-based chalcogenides,Cu–Zn–Sn–S nanocrystals(CZTS NCs)have emerged as a newfashioned electrocatalyst in hydrogen evolution reactions(HERs).Oleylamine(OM),a reducing surfactant and solvent,plays a significant role in the assisting synthesis of CZTS NCs due to the ligand effect.Herein,we adopted a facile one-pot colloidal method for achieving the structure evolution of CZTS NCs from 2D nanosheets to 1D nanorods assisted through the continuous addition of OM.During the process,the mechanism of OM-induced morphology evolution was further discussed.When merely adding pure 1-dodecanethiol(DDT)as the solvent,the CZTS nanosheets were obtained.As OM was gradually added to the reaction,the CZTS NCs began to grow along the sides of the nanosheets and gradually shrink at the top,followed by the formation of stable nanorods.In acidic electrolytic conditions,the CZTS NCs with 1.0 OM addition display the optimal HER activity with a low overpotential of 561 m V at 10 m A/cm^(2) and a small Tafel slope of 157.6 m V/dec compared with other CZTS samples.The enhancement of HER activity could be attributed to the contribution of the synergistic effect of the diverse crystal facets to the reaction.
基金the National Natural Science Foundation of China (Nos.E50725414 and E50621403).
文摘Based on the analysis of the deformation in an infinite isotropic elastic matrix with an embedded elliptic crack under far field coupled tensile and shear stresses, the energy release rate and a mixed fracture criterion are obtained using an energy balance approach. The additional compliance tensor induced by a single opening elliptic microcrack in a representative volume element is derived, and the effect of microcracks with random orientations is analyzed with the Taylor＇s scheme by introducing an appropriate probability density function. A micromechanical damage model for rocks and concretes is obtained and is verified with experimental results.
基金State Key Basic Research Development Plan (Grant No. G1998010100) and the National Natural Science Foundation of China (Grant No. 39770156).
文摘Effects of Photosystem Ⅱ (PS Ⅱ) extrinsic polypeptides of oxygen-evolving complex and manganese clusters on PS Ⅱ carbonic anhydrase (CA) were studied with spinach PS Ⅱ membranes. The result supported that membrane-bound CA is located in the donor side of PS Ⅱ. The extrinsic polypeptides played an important role of maintaining CA activity. After removing manganese clusters, oxygen evolution activity was inhibited, but PSⅡ-CA activity was unchanged. It was concluded that CA activity is independent of the presence of manganese clusters, and was not directly correlated with oxygen evolution activity.
基金The work was supported by the National Key R&D Program of China(Grant No.2020YFC1511601)Fundamental Research Funds for the Central Universities(Grant No.2019SHFWLC01).
文摘Existing almost deep learning methods rely on a large amount of annotated data, so they are inappropriate for forest fire smoke detection with limited data. In this paper, a novel hybrid attention-based few-shot learning method, named Attention-Based Prototypical Network, is proposed for forest fire smoke detection. Specifically, feature extraction network, which consists of convolutional block attention module, could extract high-level and discriminative features and further decrease the false alarm rate resulting from suspected smoke areas. Moreover, we design a metalearning module to alleviate the overfitting issue caused by limited smoke images, and the meta-learning network enables achieving effective detection via comparing the distance between the class prototype of support images and the features of query images. A series of experiments on forest fire smoke datasets and miniImageNet dataset testify that the proposed method is superior to state-of-the-art few-shot learning approaches.
基金This work was supported by the China National Major Scientific and Technological Special Project for"Significant New Drugs Innovation and Development"(2019ZX09732002-006)the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(XDA12020223 and XDA12020330)+7 种基金the National Natural Science Foundation of China(81872785,81673347,31971123,32022037,81920108015,and 31930059)Shanghai Municipal Commission of Science and Technology of China(17431904400 and 19YF1457400)Institutes for Drug Discovery and Development,Chinese Academy of Sciences(CASIMM0120202008 and CASIMM0120202007)the National Key R&D Program(2020YFA0509303)Major Scientific and Technological Special Project of Zhongshan City(191022172638719 and 210205143867019)the Key R&D Program of Zhejiang Province(2020C04001)the SARS-CoV-2 emergency project of the Science and Technology Department of Zhejiang Province(2020C03129)the Leading Innovative and Entrepreneur Team Introduction Program of Hangzhou,Westlake Education Foundation and Tencent Foundation.
文摘The evolution of coronaviruses,such as SARS-CoV-2,makes broad-spectrum coronavirus preventional or therapeutical strategies highly sought after.Here we report a human angiotensin-converting enzyme 2(ACE2)-targeting monoclonal antibody,3E8,blocked the S1-subunits and pseudo-typed virus constructs from multiple coronaviruses including SARS-CoV-2,SARS-CoV-2 mutant variants(SARS-CoV-2-D614G,B.1.1.7,B.1.351,B.1.617.1,and P.1).
文摘Satisfiability problem of authorization require- ments in business process asks whether there exists an as- signment of users to tasks that satisfies all the requirements, and methods were proposed to solve this problem. However, the proposed methods are inefficient in the sense that a step of the methods is searching all the possible assignments, which is time-consuming. This work proposes a method to solve the satisfiability problem of authorization requirements with- out browsing the assignments space. Our method uses im- proved separation of duty algebra （ISoDA） to describe a sat- isfiability problem of qualification requirements and quan- tification requirements （Separation of Duty and Binding of Duty requirements）. Thereafter, ISoDA expressions are re- duced into multi-mutual-exclusive expressions. The satisfia- bilities of multi-mutual-exclusive expressions are determined by an efficient algorithm proposed in this study. The experiment shows that our method is faster than the state-of-the-art methods.
文摘In the present paper,the analyticity of solutions to a class of degenerate elliptic equations is obtained.A kind of weighted norms are introduced and under such norms some degenerate elliptic operators are of weak coerciveness.
基金supported by the National Natural Science Foundation of China under Grant No.61170295
文摘In the system of Computer Network Collaborative Defense(CNCD),it is difficult to evaluate the trustworthiness of defense agents which are newly added to the system,since they lack historical interaction for trust evaluation.This will lead that the newly added agents could not get reasonable initial trustworthiness,and affect the whole process of trust evaluation.To solve this problem in CNCD,a trust type based trust bootstrapping model was introduced in this research.First,the division of trust type,trust utility and defense cost were discussed.Then the constraints of defense tasks were analyzed based on game theory.According to the constraints obtained,the trust type of defense agents was identified and the initial trustworthiness was assigned to defense agents.The simulated experiment shows that the methods proposed have lower failure rate of defense tasks and better adaptability in the respect of defense task execution.
文摘A green mutant was obtained among the chemically induced mutants of Rhodobacter sphaeroides 601 (RS601) and named GM309. A blue shift of 20 nm of the carotenoid absorption spectrum was found in the light-harvesting complex II (LH2) of GM309. Different from LH2 of RS601, it was found that the carotenoids in GM309-LH2 changed to be neurosporene by mutation. Neurosporene lacks a conjugate double bond, compared with the spheroidene in RS601-LH2 which has ten conjugate double bonds. As shown by absorption and circular dichroism spectroscopy, the overall structure of GM309-LH2 is little affected by this change. From fluorescence emission spectra, it is found that GM309-LH2 can transfer energy from carotenoids to Bchl-B850 without any change in efficiency. But the efficiency of energy transfer from B800 to B850 in GM309-LH2 is decreased to be 42% of that of the native. This work would provide a novel method to investigate the mechanism of excitation energy transfer in LH2.
文摘The solvability of a linear equation and the regularity of the solution are discussed. The equation is arising in a geometric problem which is concerned with the realization of Alexandroff's positive annul in R3.
