To improve the efficiency of backwashing in upflow biological aerated filter （BAF）, a novel backwashing process named air-water siphon backwashing （AWSB） was proposed and applied on laboratory scale. The effects o...To improve the efficiency of backwashing in upflow biological aerated filter （BAF）, a novel backwashing process named air-water siphon backwashing （AWSB） was proposed and applied on laboratory scale. The effects of backwashing on turbidity and suspended solid （SS） in backwashing efluent using this new backwashing process were compared with those of traditional backwashing process, namely air-water backwashing （AWB）. In AWB, the turbidity of backwashing efluent maintained 100 NUT when consumed 60 min and 10.5 L water. However, in AWSB, it declined to 44 NUT, consumed 40 min, and 7 L water. The COD removal of BAF after backwashing was also analyzed. The average removal rate of COD in the reactor backwashed by AWB and AWSB was 89.34% and 90.91%, respectively. Compared with AWB, the backwashing interval had been prolonged 35%. The volume of backwashing water in that AWSB was only 66.7% of that in AWB. The results demonstrated that AWSB required less water and took shorter backwashing timerelative to AWB to achieve the same turbidity of backwashing efluent, and AWSB was more effective in removing fouling than that of AWB. More significant advantage of AWSB was that the backwashing interval was effectively prolonged展开更多
With the rapid deployment of Next-Generation Networks(NGN),the research community has initiated discussions on an entirely new suite of optical enabling techniques.To pave the way for the development of future wireles...With the rapid deployment of Next-Generation Networks(NGN),the research community has initiated discussions on an entirely new suite of optical enabling techniques.To pave the way for the development of future wireless networks,this article aims to unify the existing infrared,visible light,and ultraviolet subbands while also exploring the potential of the Petahertz(PHz)band to support extremely bandwidth-thirsfy telepresence style applications.Our focus is on the emerging Petahertz Communication(PetaCom)framework,scenario-dependent propagation channels,modulation schemes,system performance,multiple access techniques,and networking.We conclude with a range of PetaCom challenges and open research issues.展开更多
APT attacks are prolonged and have multiple stages, and they usually utilize zero-day or one-day exploits to be penetrating and stealthy. Among all kinds of security tech- niques, provenance tracing is regarded as an ...APT attacks are prolonged and have multiple stages, and they usually utilize zero-day or one-day exploits to be penetrating and stealthy. Among all kinds of security tech- niques, provenance tracing is regarded as an important approach to attack investigation, as it discloses the root cause, the attacking path, and the results of attacks. However, existing techniques either suffer from the limitation of only focusing on the log type, or are high- ly susceptible to attacks, which hinder their applications in investigating APT attacks. We present CAPT, a context-aware provenance tracing system that leverages the advantages of virtualization technologies to transparently collect system events and network events out of the target machine, and processes them in the specific host which introduces no space cost to the target. CAPT utilizes the contexts of collected events to bridge the gap between them, and provides a panoramic view to the attack investigation. Our evaluation results show that CAPT achieves the efi＇ective prov- enance tracing to the attack cases, and it only produces 0.21 MB overhead in 8 hours. With our newly-developed technology, we keep the run-time overhead averages less than 4%.展开更多
Nucleotide second messengers are highly versatile signaling molecules that regulate a variety of key biological processes in bacteria.The best-studied examples are cyclic AMP(cAMP)and bis-(3'-5')-cyclic dimeri...Nucleotide second messengers are highly versatile signaling molecules that regulate a variety of key biological processes in bacteria.The best-studied examples are cyclic AMP(cAMP)and bis-(3'-5')-cyclic dimeric guanosine monophosphate(c-di-GMP),which both act as global regulators.Global regulatory frameworks of c-di-GMP and cAMP in bacteria show several parallels but also significant variances.In this review,we llustrate the global regulatory models of the two nucleotide second messengers,compare the different regulatory frameworks between c-di-GMP and cAMP,and discuss the mechanisms and physiological significance of cross-regulation between c-di-GMP and cAMP.c-di-GMP responds to numerous signals de-pendent on a great number of metabolic enzymes,and it regulates various signal transduction pathways through its huge number of effectors with varying activities.In contrast,due to the limited quantity,the cAMP metabolic enzymes and its major effector are regulated at different levels by diverse signals.cAMP performs its global regulatory function primarily by controlling the transcription of a large number of genes via cAMP receptor protein(CRP)in most bacteria.This review can help us understand how bacteria use the two typical nucleotide second messengers to effectively coordinate and integrate various physiological processes,providing theoretical guidelines for future research.展开更多
Underwater optical wireless communication (UOWC) technology facilitates high-speed data transmission among multiple nodes in underwater networks. Nevertheless, the absence of a common clock poses a challenge to achiev...Underwater optical wireless communication (UOWC) technology facilitates high-speed data transmission among multiple nodes in underwater networks. Nevertheless, the absence of a common clock poses a challenge to achieving systematic and reliable access for multiple nodes within these networks. This paper presents a time synchronization method for UOWC networks to ensure the successful execution of the media access control (MAC) protocol. In this method, the node obtains timestamps by exchanging messages with the optical access point (OAP). Subsequently, the node calculates the clock drift relative to the OAP and the propagation time,ensuring that transmitted data packets can arrive approximately at the time specified by the OAP. To validate the effect of the proposed method, an experimental UOWC prototype, including the OAP and nodes, is implemented using field programmable gate array (FPGA). The experimental results demonstrate that the maximum difference between the actual arrival times of two data packets that are expected to reach the OAP simultaneously according to the MAC protocol meets the requirements of the quasi-synchronous code division multiple access (QS-CDMA) system, thereby substantiating the effectiveness of this synchronization method.展开更多
The 2-meter High-speed Free-jet Wind Tunnel(2 m HFWT)is China’s first large-scale open-jet trisonic wind tunnel.Compared to traditional closed high-speed wind tunnels,this wind tunnel is endowed with remarkable advan...The 2-meter High-speed Free-jet Wind Tunnel(2 m HFWT)is China’s first large-scale open-jet trisonic wind tunnel.Compared to traditional closed high-speed wind tunnels,this wind tunnel is endowed with remarkable advantages of ample test chamber space,less interference from the tunnel wall,flexible model support mode,and adjustable continuous variation of the Mach number.Nevertheless,its unique structure makes traditional wind tunnel control methods difficult to apply and brings significant challenges to wind tunnel flow field control.In this paper,a flow field control system is designed for the 2 m HFWT by comprehensively using advanced control technologies such as neural network,gain scheduling,feedforward control,and adaptive control.Through practical application tests,it is proved that the proposed control system successfully solves the problem of high-precision flow field control under continual depletion of storage tank pressure,and realizes distinctive functions of adaptive static pressure matching and continuously varying Mach number at supersonic speed.In addition,due to the application of workflow technology,the flow field control system can flexibly adapt to the implementation of tests of different types and operation conditions,thus fully satisfying the needs of conducting various conventional and special tests in the 2 m HFWT.展开更多
In the last decade,two-dimensional layered materials(2DLMs)have been drawing extensive attentions due to their unique properties,such as absence of surface dangling bonds,thickness-dependent bandgap,high absorption co...In the last decade,two-dimensional layered materials(2DLMs)have been drawing extensive attentions due to their unique properties,such as absence of surface dangling bonds,thickness-dependent bandgap,high absorption coeffi-cient,large specific surface area,and so on.But the high-quality growth and transfer of wafer-scale 2DLMs films is still a great challenge for the commerciali-zation of pure 2DLMs-based photodetectors.Conversely,the material growth and device fabrication technologies of three-dimensional(3D)semiconductors photodetectors tend to be gradually matured.However,the further improvement of the photodetection performance is limited by the difficult heterogeneous inte-gration or the inferior crystal quality via heteroepitaxy.Fortunately,2D/3D van der Waals heterostructures(vdWH)combine the advantages of the two types of materials simultaneously,which may provide a new platform for developing high-performance optoelectronic devices.Here,we first discuss the unique advantages of 2D/3D vdWH for the future development of photodetection field and simply introduce the structure categories,working mechanisms,and the typical fabrication methods of 2D/3D vdWH photodetector.Then,we outline the recent progress on 2D/3D vdWH-based photodetection devices integrating 2DLMs with the traditional 3D semiconductor materials,including Si,Ge,GaAs,AlGaN,SiC,and so on.Finally,we highlight the current challenges and pros-pects of heterointegrating 2DLMs with traditional 3D semiconductors toward photodetection applications.展开更多
本文报道了一种快速、可控合成单层MoS_(2)纳米-微米带的方法:通过在蓝宝石衬底上旋涂Na_(2)MoO_(4)和NaOH的混合溶液后一步化学气相沉积硫化的方式进行生长.其中,通过改变NaOH的浓度,对气-液-固生长过程中的反应物液滴流动性进行调控,...本文报道了一种快速、可控合成单层MoS_(2)纳米-微米带的方法:通过在蓝宝石衬底上旋涂Na_(2)MoO_(4)和NaOH的混合溶液后一步化学气相沉积硫化的方式进行生长.其中,通过改变NaOH的浓度,对气-液-固生长过程中的反应物液滴流动性进行调控,我们实现了对所获得的MoS_(2)的形貌和取向的调控;同时,通过改变生长时间,可以实现对MoS_(2)层数的调控.利用这种方法,我们获得了最窄宽度仅为200 nm,纵横比超过100的单层MoS_(2)纳米-微米带,且表征证明其具有很高的晶体质量.同时,我们还用该MoS_(2)纳米带作为沟道材料,制备了光电晶体管,测试表明其具有高达9×10^(5)的电流开/关比、超过10^(5)的光暗电流比以及高达8.6 A W^(-1)的响应度,展现了其在电子和光电子器件中的应用潜力.展开更多
Variations of levels,possible source and air mass transmission were investigated for 16 USEPA priority-controlled PAHs in PM2.5 during 2018 Chinese Spring Festival(CSF)in Xiangyang City,central China which is the Nort...Variations of levels,possible source and air mass transmission were investigated for 16 USEPA priority-controlled PAHs in PM2.5 during 2018 Chinese Spring Festival(CSF)in Xiangyang City,central China which is the North-South pollutant airmass transport channel of China.Totally 37 samples were collected.Mass concentrations of 16 PAHs for the Pre–CSF day(Pre–CSFD),during the CSF day(CSFD)and after the CSF day(Af–CSFD)are 33.78±17.68 ng/m3,22.98±6.49 ng/m3,and 8.99±4.44 ng/m3,respectively.High resolution samples showed that 16 PAHs are higher in the morning(06:00–11:00)or afternoon(11:30–16:30),than those in the evening(17:00–22:00)and at night(22:30–05:30),whereas the result is reversed during the CSFD.Fireworks burning can obviously increase the mass concentration of PAHs.Air mass trajectory indicated that Xiangyang is a sink area of pollutants for northwest and southeast,and the sources of the northeast and southwest.The air mass only can be transmitted out through northeast and southwest.It is effective for improvement of air quality in Wuhan and Hunan to control fireworks emission in Henan and local areas.Fireworks burning was an important source for PAHs during CSFD,biomass,coal combustion,and traffic emission were the main sources of PAHs for Pre–CSFD and Af–CSFD periods.The health risk on the CSFD was higher than the acceptable levels,especially during the intensive fireworks burning,the risk value far exceed 1.0×10^-4,controlling burning fireworks is required.展开更多
To study the pesticide effect, action mode, structure-activity relationships (SARs) of anthranilic diamide insecticide and screen highly active pesticides, novel anthranilic diamide derivatives were synthesized.Bioass...To study the pesticide effect, action mode, structure-activity relationships (SARs) of anthranilic diamide insecticide and screen highly active pesticides, novel anthranilic diamide derivatives were synthesized.Bioassays indicated that all of the title compounds displayed 100% mortality against diamondback moth and oriental armyworm at 100 mg/L, among which 12 v and 12 w showed 100% insecticidal acitvity at 5 mg/L. Surprisingly compound 12 w exhibited better insecticidal acitvity than commercialized chlorantraniliprole against Pyrausta nubilalis (0.1 mg/L) and Cnaphalocrocis Medinalis (2 mg/L). 3 D-QSAR and SARs statistical analysis revealed that title compounds with R^2 fixed as methoxy had the highest probability possessing high activity. The calcium fluorescence measurements on neurons revealed that E series compounds containing pyrazinyl may have a molecular target different from caffeine on ryanodine receptors rather than the voltage-gated calcium channel present on cytomembran.展开更多
The Rowhammer bug is a novel micro-architectural security threat, enabling powerful privilege-escalation attacks on various mainstream platforms. It works by actively flipping bits in Dynamic Random Access Memory(DRAM...The Rowhammer bug is a novel micro-architectural security threat, enabling powerful privilege-escalation attacks on various mainstream platforms. It works by actively flipping bits in Dynamic Random Access Memory(DRAM) cells with unprivileged instructions. In order to set up Rowhammer against binaries in the Linux page cache, the Waylaying algorithm has previously been proposed. The Waylaying method stealthily relocates binaries onto exploitable physical addresses without exhausting system memory. However, the proof-of-concept Waylaying algorithm can be easily detected during page cache eviction because of its high disk I/O overhead and long running time. This paper proposes the more advanced Memway algorithm, which improves on Waylaying in terms of both I/O overhead and speed. Running time and disk I/O overhead are reduced by 90% by utilizing Linux tmpfs and inmemory swapping to manage eviction files. Furthermore, by combining Memway with the unprivileged posix fadvise API, the binary relocation step is made 100 times faster. Equipped with our Memway+fadvise relocation scheme,we demonstrate practical Rowhammer attacks that take only 15–200 minutes to covertly relocate a victim binary,and less than 3 seconds to flip the target instruction bit.展开更多
Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode material doped with Ti and La co-doping were synthesized through a solid-state method.The bi-functions of the Ti and La co-doping is realized.On the one hand,the stability o...Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode material doped with Ti and La co-doping were synthesized through a solid-state method.The bi-functions of the Ti and La co-doping is realized.On the one hand,the stability of the LiNi_(0.5)Mn_(1.5)O_(4)crystal structure is enhanced and the Mn3t interference inside the material is reduced by the Ti doping.On the other hand,the co-doped La contributes to the formation of Li_(0.5)La_(0.5)TiO_(3)(LLTO)superionic conductor incorporated in the bulk LiNi_(0.5)Mn_(1.5)O_(4)phase,thereby enhancing the Li diffusion.With the help of XRD,FTIR,SEM and STEM techniques,La and Ti in the crystallographic structure and the dispersion of the LLTO superionic conductor in the bulk LNMO spinel are discussed.At the optimized molar ratio of 20:1 between LNMO and LLTO,the composite exhibits the best electrochemical performances in terms of the reversible capacity,rate capability and cycling stability.The lithium ion diffusion coefficient in the bulk LNMO phase is tripled by the LLTO superionic conductor incorporation.展开更多
Fourteen avermectin B2 a aglycon derivatives were designed and synthesized after removing the oleandrose disaccharide of avermectin B2 a.Their structures were characterized by’H NMR,13 C NMR,HMRS.Preliminary bioassay...Fourteen avermectin B2 a aglycon derivatives were designed and synthesized after removing the oleandrose disaccharide of avermectin B2 a.Their structures were characterized by’H NMR,13 C NMR,HMRS.Preliminary bioassays indicated that these compounds exhibited good insecticidal activity against diamondback moth at 200 mg/L,with mortality no less than 90%.Compounds 10 b,12 a,12 c,17 demonstrated good acaricidal activity against the adult mites,larvae,and good inhibition rate of hatching to mite eggs of Tetranychus cinnabarinus.Compounds 5,10 b,10 c exhibited excellent fungicidal activity against fourteen fungal pathogens in vitro.3 D-QSAR analysis showed that the fungicidal activity of avermectin B2 a aglycon derivatives would be increased when a negatively charged and bulky group was introduced at 13-position,which will be instructive for the further modification of avermectin B2 aaglycon.展开更多
In this study,the numerical simulations of sheet metal forming processes are performed based on a fully coupled elastoplastic damage model.The effects of stress triaxiality and Lode angle are introduced into the damag...In this study,the numerical simulations of sheet metal forming processes are performed based on a fully coupled elastoplastic damage model.The effects of stress triaxiality and Lode angle are introduced into the damage evolution law to capture the loading-path-dependent failure.The proposed constitutive model is implemented into the finite element(FE)code ABAQUS/Explicit via the user-defined subroutine(VUMAT).Next,the identification procedure for DP780 based on the hybrid experimental-numerical method is presented in detail.The numerical results of simple tests are compared with the experiments,and obvious improvement is observed for the proposed model under various loading paths.Finally,the model is applied to predict the edge fracture during sheet blanking process.The predicted global load–displacement responses and crack paths have a good agreement with the experimental results,indicating that the model holds great potentials in simulation of metal forming processes.展开更多
One of the major challenges to build a task-oriented dialogue system is that dialogue state transition frequently happens between multiple domains such as booking hotels or restaurants.Recently,the encoder-decoder mod...One of the major challenges to build a task-oriented dialogue system is that dialogue state transition frequently happens between multiple domains such as booking hotels or restaurants.Recently,the encoder-decoder model based on the end-to-end neural network has become an attractive approach to meet this challenge.However,it usually requires a sufficiently large amount of training data and it is not flexible to handle dialogue state transition.This paper addresses these problems by proposing a simple but practical framework called Multi-Domain KB-BOT(MDKB-BOT),which leverages both neural networks and rule-based strategy in natural language understanding(NLU)and dialogue management(DM).Experiments on the data set of the Chinese Human-Computer Dialogue Technology Evaluation Campaign show that MDKB-BOT achieves competitive performance on several evaluation metrics,including task completion rate and user satisfaction.展开更多
基金supported by the National Natural Science Foundation of China (No. 30700010)the Eleventh Five-Year Plan National Key Technology R&D Program of China (No. 2006BAD07A01)+1 种基金the National Gongyixing Hangye Kejizhuanxiang (No. 200803033)the Special Program for Water Pollution Control of Taihu Lake in Jiangsu Province (No. BK2007741)
文摘To improve the efficiency of backwashing in upflow biological aerated filter （BAF）, a novel backwashing process named air-water siphon backwashing （AWSB） was proposed and applied on laboratory scale. The effects of backwashing on turbidity and suspended solid （SS） in backwashing efluent using this new backwashing process were compared with those of traditional backwashing process, namely air-water backwashing （AWB）. In AWB, the turbidity of backwashing efluent maintained 100 NUT when consumed 60 min and 10.5 L water. However, in AWSB, it declined to 44 NUT, consumed 40 min, and 7 L water. The COD removal of BAF after backwashing was also analyzed. The average removal rate of COD in the reactor backwashed by AWB and AWSB was 89.34% and 90.91%, respectively. Compared with AWB, the backwashing interval had been prolonged 35%. The volume of backwashing water in that AWSB was only 66.7% of that in AWB. The results demonstrated that AWSB required less water and took shorter backwashing timerelative to AWB to achieve the same turbidity of backwashing efluent, and AWSB was more effective in removing fouling than that of AWB. More significant advantage of AWSB was that the backwashing interval was effectively prolonged
基金supported by the Key Program of the National Natural Science Foundation of China(No.61631018),Key Research Program of Frontier Sciences of CAS(No.QYZDY-SSW-JSC003)Strategic Priority Research Program of CAS(No.XDA22000000).L.Hanzo would like to acknowledge the financial support of the Engineering and Physical Sciences Research Council projects EP/P034284/1 and EP/P003990/1(COALESCE)as well as of the European Research Council’s Advanced Fellow Grant QuantCom(Grant No.789028).
文摘With the rapid deployment of Next-Generation Networks(NGN),the research community has initiated discussions on an entirely new suite of optical enabling techniques.To pave the way for the development of future wireless networks,this article aims to unify the existing infrared,visible light,and ultraviolet subbands while also exploring the potential of the Petahertz(PHz)band to support extremely bandwidth-thirsfy telepresence style applications.Our focus is on the emerging Petahertz Communication(PetaCom)framework,scenario-dependent propagation channels,modulation schemes,system performance,multiple access techniques,and networking.We conclude with a range of PetaCom challenges and open research issues.
基金partially supported by the NSFC-General Technology Basic Research Joint Fund (U1536204)the National Key Technologies R&D Program (2014BAH41B00)+3 种基金the National Nature Science Foundation of China (61672394 61373168 61373169)the National High-tech R&D Program of China (863 Program) (2015AA016004)
文摘APT attacks are prolonged and have multiple stages, and they usually utilize zero-day or one-day exploits to be penetrating and stealthy. Among all kinds of security tech- niques, provenance tracing is regarded as an important approach to attack investigation, as it discloses the root cause, the attacking path, and the results of attacks. However, existing techniques either suffer from the limitation of only focusing on the log type, or are high- ly susceptible to attacks, which hinder their applications in investigating APT attacks. We present CAPT, a context-aware provenance tracing system that leverages the advantages of virtualization technologies to transparently collect system events and network events out of the target machine, and processes them in the specific host which introduces no space cost to the target. CAPT utilizes the contexts of collected events to bridge the gap between them, and provides a panoramic view to the attack investigation. Our evaluation results show that CAPT achieves the efi＇ective prov- enance tracing to the attack cases, and it only produces 0.21 MB overhead in 8 hours. With our newly-developed technology, we keep the run-time overhead averages less than 4%.
基金funded by the National Natural Science Foundation of China(Nos.32370023,32370583,31970036,and 31900401)Natural Science Foundation of the Jiangsu Higher Education Institutions of China(20KJB180001 and 20KJA180007)+2 种基金Natural Science Foundation of Jiangsu Province(BK20210920 and BK20231350)Jiangsu Agricultural Science and Technology Innovation Fund(Cx223125)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Nucleotide second messengers are highly versatile signaling molecules that regulate a variety of key biological processes in bacteria.The best-studied examples are cyclic AMP(cAMP)and bis-(3'-5')-cyclic dimeric guanosine monophosphate(c-di-GMP),which both act as global regulators.Global regulatory frameworks of c-di-GMP and cAMP in bacteria show several parallels but also significant variances.In this review,we llustrate the global regulatory models of the two nucleotide second messengers,compare the different regulatory frameworks between c-di-GMP and cAMP,and discuss the mechanisms and physiological significance of cross-regulation between c-di-GMP and cAMP.c-di-GMP responds to numerous signals de-pendent on a great number of metabolic enzymes,and it regulates various signal transduction pathways through its huge number of effectors with varying activities.In contrast,due to the limited quantity,the cAMP metabolic enzymes and its major effector are regulated at different levels by diverse signals.cAMP performs its global regulatory function primarily by controlling the transcription of a large number of genes via cAMP receptor protein(CRP)in most bacteria.This review can help us understand how bacteria use the two typical nucleotide second messengers to effectively coordinate and integrate various physiological processes,providing theoretical guidelines for future research.
基金supported in part by the National Key Research and Development Program of China under Grant 2022YFB2903400in part by the Strategic Priority Research Program of CAS under Grant XDA22000000in part by the National Natural Science Foundation of China under Grants 62301525 and 62101526.
文摘Underwater optical wireless communication (UOWC) technology facilitates high-speed data transmission among multiple nodes in underwater networks. Nevertheless, the absence of a common clock poses a challenge to achieving systematic and reliable access for multiple nodes within these networks. This paper presents a time synchronization method for UOWC networks to ensure the successful execution of the media access control (MAC) protocol. In this method, the node obtains timestamps by exchanging messages with the optical access point (OAP). Subsequently, the node calculates the clock drift relative to the OAP and the propagation time,ensuring that transmitted data packets can arrive approximately at the time specified by the OAP. To validate the effect of the proposed method, an experimental UOWC prototype, including the OAP and nodes, is implemented using field programmable gate array (FPGA). The experimental results demonstrate that the maximum difference between the actual arrival times of two data packets that are expected to reach the OAP simultaneously according to the MAC protocol meets the requirements of the quasi-synchronous code division multiple access (QS-CDMA) system, thereby substantiating the effectiveness of this synchronization method.
文摘The 2-meter High-speed Free-jet Wind Tunnel(2 m HFWT)is China’s first large-scale open-jet trisonic wind tunnel.Compared to traditional closed high-speed wind tunnels,this wind tunnel is endowed with remarkable advantages of ample test chamber space,less interference from the tunnel wall,flexible model support mode,and adjustable continuous variation of the Mach number.Nevertheless,its unique structure makes traditional wind tunnel control methods difficult to apply and brings significant challenges to wind tunnel flow field control.In this paper,a flow field control system is designed for the 2 m HFWT by comprehensively using advanced control technologies such as neural network,gain scheduling,feedforward control,and adaptive control.Through practical application tests,it is proved that the proposed control system successfully solves the problem of high-precision flow field control under continual depletion of storage tank pressure,and realizes distinctive functions of adaptive static pressure matching and continuously varying Mach number at supersonic speed.In addition,due to the application of workflow technology,the flow field control system can flexibly adapt to the implementation of tests of different types and operation conditions,thus fully satisfying the needs of conducting various conventional and special tests in the 2 m HFWT.
基金Funding information National Natural Science Foundation of China,Grant/Award Numbers:61974174,61904184,62174061,62174063National Key Research and Development Program of China,Grant/Award Number:2022YFB3605104+3 种基金Key Research and Development Program of Hubei Province,Grant/Award Number:2021BAA071Key Laboratory of Infrared Imaging Materials and Detectors,the Shanghai Institute of Technical Physics,the Chinese Academy of Sciences,Grant/Award Number:IIMDKFJJ-21-07Fundamental Research Funds for the Central Universities,Grant/Award Number.2020kfyXJJS124Director Fund of WNLO。
文摘In the last decade,two-dimensional layered materials(2DLMs)have been drawing extensive attentions due to their unique properties,such as absence of surface dangling bonds,thickness-dependent bandgap,high absorption coeffi-cient,large specific surface area,and so on.But the high-quality growth and transfer of wafer-scale 2DLMs films is still a great challenge for the commerciali-zation of pure 2DLMs-based photodetectors.Conversely,the material growth and device fabrication technologies of three-dimensional(3D)semiconductors photodetectors tend to be gradually matured.However,the further improvement of the photodetection performance is limited by the difficult heterogeneous inte-gration or the inferior crystal quality via heteroepitaxy.Fortunately,2D/3D van der Waals heterostructures(vdWH)combine the advantages of the two types of materials simultaneously,which may provide a new platform for developing high-performance optoelectronic devices.Here,we first discuss the unique advantages of 2D/3D vdWH for the future development of photodetection field and simply introduce the structure categories,working mechanisms,and the typical fabrication methods of 2D/3D vdWH photodetector.Then,we outline the recent progress on 2D/3D vdWH-based photodetection devices integrating 2DLMs with the traditional 3D semiconductor materials,including Si,Ge,GaAs,AlGaN,SiC,and so on.Finally,we highlight the current challenges and pros-pects of heterointegrating 2DLMs with traditional 3D semiconductors toward photodetection applications.
基金supported by the National Natural Science Foundation of China(62174063,62174061,and 61974174)the National Key Research and Development Program of China(2022YFB3605104)+3 种基金the Key Research and Development Program of Hubei Province(2021BAA071)the Natural Science Foundation of Hubei Province(2022CFB011)the Key Laboratory of Infrared Imaging Materials and Detectors,Shanghai Institute of Technical Physics,Chinese Academy of Sciences(IIMDKFJJ-21-07)the Fundamental Research Funds for the Central Universities(2020kfyXJJS124)。
文摘本文报道了一种快速、可控合成单层MoS_(2)纳米-微米带的方法:通过在蓝宝石衬底上旋涂Na_(2)MoO_(4)和NaOH的混合溶液后一步化学气相沉积硫化的方式进行生长.其中,通过改变NaOH的浓度,对气-液-固生长过程中的反应物液滴流动性进行调控,我们实现了对所获得的MoS_(2)的形貌和取向的调控;同时,通过改变生长时间,可以实现对MoS_(2)层数的调控.利用这种方法,我们获得了最窄宽度仅为200 nm,纵横比超过100的单层MoS_(2)纳米-微米带,且表征证明其具有很高的晶体质量.同时,我们还用该MoS_(2)纳米带作为沟道材料,制备了光电晶体管,测试表明其具有高达9×10^(5)的电流开/关比、超过10^(5)的光暗电流比以及高达8.6 A W^(-1)的响应度,展现了其在电子和光电子器件中的应用潜力.
基金supported by the National Key Research and Development Program of China(No.2017YFC0212603)the National Natural Science Foundation of China(No.41773124)+2 种基金the Open Research Program of Laboratory of Basin Hydrology and Wetland Eco-restoration,China University of Geosciences(Wuhan)(No.BHWER201503(A))the Open Research Fund of Hubei Key Laboratory of Mine Environmental Pollution Con-trol&Remediation,Hubei Polytechnic University(No.201702)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(No.CUGL170208)。
文摘Variations of levels,possible source and air mass transmission were investigated for 16 USEPA priority-controlled PAHs in PM2.5 during 2018 Chinese Spring Festival(CSF)in Xiangyang City,central China which is the North-South pollutant airmass transport channel of China.Totally 37 samples were collected.Mass concentrations of 16 PAHs for the Pre–CSF day(Pre–CSFD),during the CSF day(CSFD)and after the CSF day(Af–CSFD)are 33.78±17.68 ng/m3,22.98±6.49 ng/m3,and 8.99±4.44 ng/m3,respectively.High resolution samples showed that 16 PAHs are higher in the morning(06:00–11:00)or afternoon(11:30–16:30),than those in the evening(17:00–22:00)and at night(22:30–05:30),whereas the result is reversed during the CSFD.Fireworks burning can obviously increase the mass concentration of PAHs.Air mass trajectory indicated that Xiangyang is a sink area of pollutants for northwest and southeast,and the sources of the northeast and southwest.The air mass only can be transmitted out through northeast and southwest.It is effective for improvement of air quality in Wuhan and Hunan to control fireworks emission in Henan and local areas.Fireworks burning was an important source for PAHs during CSFD,biomass,coal combustion,and traffic emission were the main sources of PAHs for Pre–CSFD and Af–CSFD periods.The health risk on the CSFD was higher than the acceptable levels,especially during the intensive fireworks burning,the risk value far exceed 1.0×10^-4,controlling burning fireworks is required.
基金supported by the National Natural Science Foundation of China(Nos. 20772060 and 21172114)
文摘To study the pesticide effect, action mode, structure-activity relationships (SARs) of anthranilic diamide insecticide and screen highly active pesticides, novel anthranilic diamide derivatives were synthesized.Bioassays indicated that all of the title compounds displayed 100% mortality against diamondback moth and oriental armyworm at 100 mg/L, among which 12 v and 12 w showed 100% insecticidal acitvity at 5 mg/L. Surprisingly compound 12 w exhibited better insecticidal acitvity than commercialized chlorantraniliprole against Pyrausta nubilalis (0.1 mg/L) and Cnaphalocrocis Medinalis (2 mg/L). 3 D-QSAR and SARs statistical analysis revealed that title compounds with R^2 fixed as methoxy had the highest probability possessing high activity. The calcium fluorescence measurements on neurons revealed that E series compounds containing pyrazinyl may have a molecular target different from caffeine on ryanodine receptors rather than the voltage-gated calcium channel present on cytomembran.
基金supported by the National Natural Science Foundation of China(Nos.U1836112,U1536204,and 61876134)the Fundamental Research Funds for the Central Universities(No.2042018kf10281)+1 种基金Foundation of Key Lab of Information Assurance and Technology(No.KJ-17-101)China Scholarship Council
文摘The Rowhammer bug is a novel micro-architectural security threat, enabling powerful privilege-escalation attacks on various mainstream platforms. It works by actively flipping bits in Dynamic Random Access Memory(DRAM) cells with unprivileged instructions. In order to set up Rowhammer against binaries in the Linux page cache, the Waylaying algorithm has previously been proposed. The Waylaying method stealthily relocates binaries onto exploitable physical addresses without exhausting system memory. However, the proof-of-concept Waylaying algorithm can be easily detected during page cache eviction because of its high disk I/O overhead and long running time. This paper proposes the more advanced Memway algorithm, which improves on Waylaying in terms of both I/O overhead and speed. Running time and disk I/O overhead are reduced by 90% by utilizing Linux tmpfs and inmemory swapping to manage eviction files. Furthermore, by combining Memway with the unprivileged posix fadvise API, the binary relocation step is made 100 times faster. Equipped with our Memway+fadvise relocation scheme,we demonstrate practical Rowhammer attacks that take only 15–200 minutes to covertly relocate a victim binary,and less than 3 seconds to flip the target instruction bit.
基金This work is financially supported by the National Natural Science Foundation of China(NSFC,contract no.21875154 and 21473120)The authors also thank the Ministry of Science and Technology of the People's Republic of China,China(Contract No.2015AA034601).
文摘Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode material doped with Ti and La co-doping were synthesized through a solid-state method.The bi-functions of the Ti and La co-doping is realized.On the one hand,the stability of the LiNi_(0.5)Mn_(1.5)O_(4)crystal structure is enhanced and the Mn3t interference inside the material is reduced by the Ti doping.On the other hand,the co-doped La contributes to the formation of Li_(0.5)La_(0.5)TiO_(3)(LLTO)superionic conductor incorporated in the bulk LiNi_(0.5)Mn_(1.5)O_(4)phase,thereby enhancing the Li diffusion.With the help of XRD,FTIR,SEM and STEM techniques,La and Ti in the crystallographic structure and the dispersion of the LLTO superionic conductor in the bulk LNMO spinel are discussed.At the optimized molar ratio of 20:1 between LNMO and LLTO,the composite exhibits the best electrochemical performances in terms of the reversible capacity,rate capability and cycling stability.The lithium ion diffusion coefficient in the bulk LNMO phase is tripled by the LLTO superionic conductor incorporation.
基金supported by the National Key R&D Program of China (No.2018YFD0200100)
文摘Fourteen avermectin B2 a aglycon derivatives were designed and synthesized after removing the oleandrose disaccharide of avermectin B2 a.Their structures were characterized by’H NMR,13 C NMR,HMRS.Preliminary bioassays indicated that these compounds exhibited good insecticidal activity against diamondback moth at 200 mg/L,with mortality no less than 90%.Compounds 10 b,12 a,12 c,17 demonstrated good acaricidal activity against the adult mites,larvae,and good inhibition rate of hatching to mite eggs of Tetranychus cinnabarinus.Compounds 5,10 b,10 c exhibited excellent fungicidal activity against fourteen fungal pathogens in vitro.3 D-QSAR analysis showed that the fungicidal activity of avermectin B2 a aglycon derivatives would be increased when a negatively charged and bulky group was introduced at 13-position,which will be instructive for the further modification of avermectin B2 aaglycon.
基金supported by the Fundamental Research Funds for the Central Universities(20CX06023A)Qingdao Postdoctoral Applied Research Program(QD20190014)+1 种基金National Natural Science Foundation of China(No.11802131)Key R&D Program in Shandong Province(2019GHZ001).
文摘In this study,the numerical simulations of sheet metal forming processes are performed based on a fully coupled elastoplastic damage model.The effects of stress triaxiality and Lode angle are introduced into the damage evolution law to capture the loading-path-dependent failure.The proposed constitutive model is implemented into the finite element(FE)code ABAQUS/Explicit via the user-defined subroutine(VUMAT).Next,the identification procedure for DP780 based on the hybrid experimental-numerical method is presented in detail.The numerical results of simple tests are compared with the experiments,and obvious improvement is observed for the proposed model under various loading paths.Finally,the model is applied to predict the edge fracture during sheet blanking process.The predicted global load–displacement responses and crack paths have a good agreement with the experimental results,indicating that the model holds great potentials in simulation of metal forming processes.
基金This work was supported by Beijing Natural Science Foundation(No.4174098)National Natural Science Foundation of China(No.61702047)the Fundamental Research Funds for the Central Universities(No.2017RC02).
文摘One of the major challenges to build a task-oriented dialogue system is that dialogue state transition frequently happens between multiple domains such as booking hotels or restaurants.Recently,the encoder-decoder model based on the end-to-end neural network has become an attractive approach to meet this challenge.However,it usually requires a sufficiently large amount of training data and it is not flexible to handle dialogue state transition.This paper addresses these problems by proposing a simple but practical framework called Multi-Domain KB-BOT(MDKB-BOT),which leverages both neural networks and rule-based strategy in natural language understanding(NLU)and dialogue management(DM).Experiments on the data set of the Chinese Human-Computer Dialogue Technology Evaluation Campaign show that MDKB-BOT achieves competitive performance on several evaluation metrics,including task completion rate and user satisfaction.
