A comparative study of model predictive control(MPC)schemes and robust Hstate feedback control(RSC)method for trajectory tracking is proposed in this paper.The main objective of this paper is to compare MPC and RSC co...A comparative study of model predictive control(MPC)schemes and robust Hstate feedback control(RSC)method for trajectory tracking is proposed in this paper.The main objective of this paper is to compare MPC and RSC controllers’performance in tracking predefined trajectory under different scenarios.MPC controller is designed based on the simple longitudinal-yaw-lateral motions of a single-track vehicle with a linear tire,which is an approximation of the more realistic model of a vehicle with double-track motion with a non-linear tire mode.RSC is designed on the basis of the same method as adopted for the MPC controller to achieve a fair comparison.Then,three test cases are built in CarSim-Simulink joint platform.Specifically,the verification test is used to test the tracking accuracy of MPC and RSC controller under well road conditions.Besides,the double lane change test with low road adhesion is designed to find the maximum velocity that both controllers can carry out while guaranteeing stability.Furthermore,an extreme curve test is built where the road adhesion changes suddenly,in order to test the performance of both controllers under extreme conditions.Finally,the advantages and disadvantages of MPC and RSC under different scenarios are also discussed.展开更多
Road intersection is one of the most complex and accident-prone traffic scenarios,so it’s challenging for autonomous vehicles(AVs)to make safe and efficient decisions at the intersections.Most of the related studies ...Road intersection is one of the most complex and accident-prone traffic scenarios,so it’s challenging for autonomous vehicles(AVs)to make safe and efficient decisions at the intersections.Most of the related studies focus on the solution to a single scenario or only guarantee safety without considering driving efficiency.To address these problems,this study proposed a deep reinforcement learning enabled decision-making framework for AVs to drive through intersections automatically,safely and efficiently.The mapping relationship between traffic images and vehicle operations was obtained by an end-to-end decision-making framework established by convolutional neural networks.Traffic images collected at two timesteps were used to calculate the relative velocity between vehicles.Markov decision process was employed to model the interaction between AVs and other vehicles,and the deep Q-network algorithm was utilized to obtain the optimal driving policy regarding safety and efficiency.To verify the effectiveness of the proposed decision-making framework,the top three accident-prone crossing path crash scenarios at intersections were simulated,when different initial vehicle states were adopted for better generalization capability.The results showed that the developed method could make AVs drive safely and efficiently through intersections in all of the tested scenarios.展开更多
The late Quaternary ice rafted detritus (IRD) events in the Chukchi Basin, western Arctic Ocean are indications of the provenance of the coarser detritus and ice export events, and also document the evolutionary histo...The late Quaternary ice rafted detritus (IRD) events in the Chukchi Basin, western Arctic Ocean are indications of the provenance of the coarser detritus and ice export events, and also document the evolutionary histories of Beaufort Gyre and the North American Ice Sheet (NAIS). The sediment of core M03 from the Chukchi Basin was selected to study the regional response to the ice export events and the NAIS variability. The stratigraphic framework of M03 was established by a combination of lithological features and downcore color change cycles, AMS14C dating with foraminifera abundance and IRD events. The core was also compared with the adjacent core NWR 5 from the Northwind Ridge area. The core extends back to Marine Isotope Stage (MIS) 7. A sedimentary hiatus of 10―20 ka might occur between 16 to 20 cm core depth. Seven IRD events are distinguished from the studied core and are presented during the early MIS 1, MIS 3, MIS 5 and late MIS 7. These IRD are transported by sea ice and icebergs, which were exported to the Beaufort Sea from the M'Clure Strait Ice Stream, Canadian Arctic Archipelago, and brought to the Chukchi Basin by the Beaufort Gyre.展开更多
The new energy vehicle plays a crucial role in green transportation,and the energy management strategy of hybrid power systems is essential for ensuring energy-efficient driving.This paper presents a state-of-the-art ...The new energy vehicle plays a crucial role in green transportation,and the energy management strategy of hybrid power systems is essential for ensuring energy-efficient driving.This paper presents a state-of-the-art survey and review of reinforcement learning-based energy management strategies for hybrid power systems.Additionally,it envisions the outlook for autonomous intelligent hybrid electric vehicles,with reinforcement learning as the foundational technology.First of all,to provide a macro view of historical development,the brief history of deep learning,reinforcement learning,and deep reinforcement learning is presented in the form of a timeline.Then,the comprehensive survey and review are conducted by collecting papers from mainstream academic databases.Enumerating most of the contributions based on three main directions—algorithm innovation,powertrain innovation,and environment innovation—provides an objective review of the research status.Finally,to advance the application of reinforcement learning in autonomous intelligent hybrid electric vehicles,future research plans positioned as“Alpha HEV”are envisioned,integrating Autopilot and energy-saving control.展开更多
Suppression of uncontrollable dendrite growth and water-induced side reactions of Zn metal anodes is crucial for achieving long-lasting cycling stability and facilitating the practical implementations of aqueous Zn-me...Suppression of uncontrollable dendrite growth and water-induced side reactions of Zn metal anodes is crucial for achieving long-lasting cycling stability and facilitating the practical implementations of aqueous Zn-metal batteries.To address these challenges,we report in this study a functional nitro-cellulose interfacial layer(NCIL)on the surface of Zn anodes enlightened by a nitro-coordination chemistry strategy.The NCIL exhibits strong zincophilicity and superior coordination capability with Zn^(2+)due to the highly electronegative and highly nucleophilic nature of the nitro functional group.This characteristic facilitates a rapid Zn-ion desolvation process and homogeneous Zn plating,effectively preventing H_(2) evolution and dendrite formation.Additionally,the negatively charged surface of NCIL acts as a shield,repelling SO_(4)^(2-)anions and inhibiting corrosive reactions on the Zn surface.Remarkably,reversible and stable Zn plating/stripping is achieved for over 5100 h at a current density of 1 mA cm^(-2),which is nearly 30 times longer than that of bare Zn anodes.Furthermore,the Zn/V_(2)O_(5) full cells with the functional interface layer deliver a high-capacity retention of 80.3%for over 10,000 cycles at 5 A g^(-1).This research offers valuable insights for the rational development of advanced protective interface layers in order to achieve ultra-long-lifeZnmetal batteries.展开更多
Effective monitoring and management of microbial risk factors in wastewater treatment plants(WWTPs)effluents require a comprehensive investigation of these risks.A global survey on microbial risk factors in WWTP efflu...Effective monitoring and management of microbial risk factors in wastewater treatment plants(WWTPs)effluents require a comprehensive investigation of these risks.A global survey on microbial risk factors in WWTP effluents could reveal important insights into their risk features.This study aims to explore the abundance and types of antibiotic resistance genes(ARGs),virulence factor genes(VFGs),the vector of ARG/VFG,and dominant pathogens in global WWTP effluents.We collected 113 metagenomes of WWTP effluents from the Sequence Read Archive of the National Center for Biotechnology Information and characterized the microbial risk factors.Our results showed that multidrug resistance was the dominant ARG type,while offensive virulence factors were the most abundant type of VFGs.The most dominant types of ARGs in the vector of plasmid and phage were both aminoglycoside resistance,which is concerning as aminoglycosides are often a last resort for treating multi-resistant infections.Acinetobacter baumannii was the most dominant pathogen,rather than Escherichia coli,and a weak negative correlation between Escherichia coli and two other dominant pathogens(Acinetobacter baumannii and Bacteroides uniformis)suggests that using Escherichia coli as a biological indicator for all pathogens in WWTP effluents may not be appropriate.The Getah virus was the most dominant virus found in global WWTP effluents.Our study presents a comprehensive global-scale investigation of microbial risk factors in WWTP effluents,providing valuable insights into the potential risks associated with WWTP effluents and contributing to the monitoring and control of these risks.展开更多
The in-wheel motor(IWM)-driven electric vehicles(EVs)attract increasing attention due to their advantages in dimensions and controllability.The majority of the current studies on IWM are carried out with the assumptio...The in-wheel motor(IWM)-driven electric vehicles(EVs)attract increasing attention due to their advantages in dimensions and controllability.The majority of the current studies on IWM are carried out with the assumption of an ideal actuator,in which the coupling effects between the non-ideal IWM and vehicle are ignored.This paper uses the braking process as an example to investigate the longitudinal-vertical dynamics of IWM-driven EVs while considering the mechanical-electrical coupling effect.First,a nonlinear switched reluctance motor model is developed,and the unbalanced electric magnetic force(UEMF)induced by static and dynamic mixed eccentricity is analyzed.Then,the UEMF is decomposed into longitudinal and vertical directions and included in the longitudinal-vertical vehicle dynamics.The coupling dynamics are demonstrated under different vehicle braking scenarios;numerical simulations are carried out for various road grades,road friction,and vehicle velocities.A novel dynamics vibration absorbing system is adopted to improve the vehicle dynamics.Finally,the simulation results show that vehicle vertical dynamic performance is enhanced.展开更多
Driver distraction has been deemed a major cause of traffic accidents.However,drivers’brain response activities to different distraction types have not been well investigated.The purpose of this study is to investiga...Driver distraction has been deemed a major cause of traffic accidents.However,drivers’brain response activities to different distraction types have not been well investigated.The purpose of this study is to investigate the response of electroencephalography(EEG)activities to different distraction tasks.In the conducted simulation tests,three secondary tasks(i.e.,a clock task,a 2-back task,and a navigation task)are designed to induce different types of driver distractions.Twenty-four participants are recruited for the designed tests,and differences in drivers’brain response activities concerning distraction types are investigated.The results show that the differences in comprehensive distraction are more significant than that in single cognitive distraction.Friedman test and post hoc two-tailed Nemenyi test are conducted to further identify the differences in band activities among brain regions.The results show that the theta energy in the frontal lobe is significantly higher than that in other brain regions in distracted driving,whereas the alpha energy in the temporal lobe significantly decreases compared to other brain regions.These results provide theoretical references for the development of distraction detection systems based on EEG signals.展开更多
AIM: To construct a recombinant strain which expresses BabA of Helicobacter pylori(H pylori) and to study the immunogenicity of BabA.METHODS: BabA2 DNA was amplified by PCR and inserted into the prokaryotie expression...AIM: To construct a recombinant strain which expresses BabA of Helicobacter pylori(H pylori) and to study the immunogenicity of BabA.METHODS: BabA2 DNA was amplified by PCR and inserted into the prokaryotie expression vector pET-22b (+) and expressed in the BL21 (DE3) E.coli strain. Furthermore,BabA immunogenicity was studied by animal test.RESULTS: DNA sequence analysis showed the sequence of BabA2 DNA was the same as the one published by GenBank.The BabA recombinant protein accounted for 34.8% of the total bacterial protein. The serum from H pylori infected patients and Balb/c miced immunized with BabA itself could recognize rBabA.CONCLUSION: BabA recombinant protein may be an potential vaccine for control and treatment of Hpyloriinfection.展开更多
Large-head variable-amplitude pump turbines(PTs) encounter serious transient hydraulic instability issues. To explore the evolution mechanisms of pressure fluctuations(PFs) and flow patterns inside large-head variable...Large-head variable-amplitude pump turbines(PTs) encounter serious transient hydraulic instability issues. To explore the evolution mechanisms of pressure fluctuations(PFs) and flow patterns inside large-head variable-amplitude PTs, the load rejection process(LRP) was investigated using a one-and three-dimensional coupled flow simulation approach. The temporal,spatial, and frequency characteristics of the fluctuating pressures were analyzed for four monitoring points using a combined time-frequency analysis approach. The results indicated that PFs during the LRP of large-head variable-amplitude PTs had a new fluctuation frequency component related to Dean vortices(DVs) in the volute, in addition to the common fluctuation frequency components related to rotor-stator interaction phenomena and local backflow vortices near the impeller inlet. The PF frequency component existed throughout the LRP and had a significant influence on the transient maximum pressure at the volute end. This study provides a useful theoretical guide for the design and optimization of large-head variable-amplitude PTs.展开更多
AIM: To express Hsp60 protein of H pylori by a constructed vector and to evaluate its immunogenicity.METHODS: Hsp60 DNA was amplified by PCR and inserted into the prokaryotie expression vector pET-22b (+), which was t...AIM: To express Hsp60 protein of H pylori by a constructed vector and to evaluate its immunogenicity.METHODS: Hsp60 DNA was amplified by PCR and inserted into the prokaryotie expression vector pET-22b (+), which was transformed into BL21 (DE3) E. coli strain to express recombinant protein. Immunogenicity of expressed Hsp60 protein was evaluated with animal experiments.RESULTS: DNA sequence analysis showed Hsp60 DNA was the same as GenBank's research. Hsp60 recombinant protein accounted for 27.2 % of the total bacterial protein,and could be recognized by the serum from H pylori infected patients and Balb/c mice immunized with Hsp60 itself.CONCLUSION: Hsp60 recombinant protein might become a potential vaccine for controlling and treating H pylori infection.展开更多
Background:Bitcoin,the most innovate digital currency as of now,created since 2008,even through experienced its ups and downs,still keeps drawing attentions to all parts of society.It relies on peer-to-peer network,ac...Background:Bitcoin,the most innovate digital currency as of now,created since 2008,even through experienced its ups and downs,still keeps drawing attentions to all parts of society.It relies on peer-to-peer network,achieved decentralization,anonymous and transparent.As the most representative digital currency,people curious to study how Bitcoin’price changes in the past.Methods:In this paper,we use monthly data from 2011 to 2016 to build a VEC model to exam how economic factors such as Custom price index,US dollar index,Dow jones industry average,Federal Funds Rate and gold price influence Bitcoin price.Result:From empirical analysis we find that all these variables do have a long-term influence.US dollar index is the biggest influence on Bitcoin price while gold price influence the least.Conclusion:From our result,we conclude that for now Bitcoin can be treated as a speculative asset,however,it is far from being a proper credit currency.展开更多
In the research for the safe and efficiently antibacterial cotton fabrics to minimize risk for human health,an organic–inorganic hybrid material of ZnO nanoparticles(NPs)and quaternary ammonium salt(QAS)was employed ...In the research for the safe and efficiently antibacterial cotton fabrics to minimize risk for human health,an organic–inorganic hybrid material of ZnO nanoparticles(NPs)and quaternary ammonium salt(QAS)was employed to modify cotton fabrics by a dipping–padding–drying method.The synergistic effects of ZnO NPs and QAS on the structure and antibacterial properties of cotton fabrics were studied in detail.Results displayed that the QAS and ZnO NPs were immobilized firmly in cotton fabric by the formation of chemical covalent bonds and silica gel structure.ZnO/QAS/cotton had a good inhibitory effect on the growth of E.coli and S.aureus,with superior antibacterial efficiency of>99.99%.ZnO/QAS/cotton preserved good mechanical property,water absorbability,and limpness.We also provided a detailed analysis of antibacterial mechanism for the hybrid materials.The contact mechanism and the Zn2+release were considered as the main mechanisms for the ZnO/QAS/cotton,while the reactive oxygen species(ROS)generation only had a little contribution to the antibacterial activity.In short,the excellent integrated properties endowed the hybrid cotton fabrics as potential application in many fields,like healthcare,food packaging.展开更多
The catalytic conversion of biomass platform chemicals using abundant non-noble metal nanocatalysts is a challenging topic.Here,high-density cobalt oxide nanoparticles loaded on biomass-derived porous N-doped carbon(N...The catalytic conversion of biomass platform chemicals using abundant non-noble metal nanocatalysts is a challenging topic.Here,high-density cobalt oxide nanoparticles loaded on biomass-derived porous N-doped carbon(NC)was fabricated by a tandem hydrothermal pyrolysis and mild nitrate decomposition process,which is a green and cheap preparation method.The Co_(3)O_(4) nanoparticles with the average size of 12 nm were uniformly distributed on the porous NC.The nanocomposites also possessed large surface area,high N content,good dispersibility in isopropanol,and furfural absorbability.Due to these characteristics,the novel cobalt nanocatalyst exhibited high catalytic activity for producing furfuryl alcohol,yielding 98.7%of the conversion and 97.1%of the selectivity at 160℃ for 6 h under 1 bar H2.The control experiments implied that both direct hydrogenation and transfer hydrogenation pathways co-existed in the hydrogenation reaction.The excellent catalytic activity of Co_(3)O_(4)@NC was attributed to the cooperative effects of porous NC and Co_(3)O_(4) nanoparticles.This approach provides a new idea to design effective high-density nonnoble metal oxide nanocatalysts for hydrogenation reactions,which can make full use of sustainable natural biomass.展开更多
Nickel (hydr)oxide (NiOH) is known to be good co-catalyst for the photoelectrochemical oxidation of water,and for the photocatalytic oxidation of organics on different semiconductors.Herein we report a greatly improve...Nickel (hydr)oxide (NiOH) is known to be good co-catalyst for the photoelectrochemical oxidation of water,and for the photocatalytic oxidation of organics on different semiconductors.Herein we report a greatly improved activity of Bi_(2)MoO_(6)(BMO) by nickel hexammine perchlorate (NiNH).Under visible light,phenol oxidation on BMO was slow.After NiNH,NiOH,and Ni^(2+)loading,a maximum rate of phenol oxidation increased by factors of approximately 16,8.8,and 4.7,respectively.With a BMO electrode,all catalysts inhibited O_(2)reduction,enhanced water (photo-)oxidation,and facilitated the charge transfer at solidliquid interface,respectively,the degree of which was always NiNH>NiOH>Ni^(2+).Solid emission spectra indicated that all catalysts improved the charge separation of BMO,the degree of which also varied as NiNH>NiOH>Ni^(2+).Furthermore,after a phenol-free aqueous suspension of NiNH/BMO was irradiated,there was a considerable Ni(Ⅲ) species,but a negligible NH_(2)radical.Accordingly,a plausible mechanism is proposed,involving the hole oxidation of Ni(Ⅱ) into Ni(Ⅳ),which is reactive to phenol oxidation,and hence promotes O_(2)reduction.Because NH_(3)is a stronger ligand than H_(2)O,the Ni(Ⅱ) oxidation is easier for Ni(NH_(3))6+than for Ni(H_(2)O)6+.This work shows a simple route how to improve BMO photocatalysis through a co-catalyst.展开更多
Distributed-drive electric vehicles(EVs)replace internal combustion engine with multiple motors,and the novel configura-tion results in new dynamic-related issues.This paper studies the coupling effects between the pa...Distributed-drive electric vehicles(EVs)replace internal combustion engine with multiple motors,and the novel configura-tion results in new dynamic-related issues.This paper studies the coupling effects between the parameters and responses of dynamic vibration-absorbing structures(DVAS)for EVs driven by in-wheel motors(IWM).Firstly,a DVAS-based quarter suspension model is developed for distributed-drive EVs,from which nine parameters and five responses are selected for the coupling effect analysis.A two-stage global sensitivity analysis is then utilized to investigate the effect of each parameter on the responses.The control of the system is then converted into a multiobjective optimization problem with the defined system parameters being the optimization variables,and three dynamic limitations regarding both motor and suspension subsystems are taken as the constraints.A particle swarm optimization approach is then used to either improve ride comfort or mitigate IWM vibration,and two optimized parameter sets for these two objects are provided at last.Simulation results provide in-depth conclusions for the coupling effects between parameters and responses,as well as a guideline on how to design system parameters for contradictory objectives.It can be concluded that either passenger comfort or motor lifespan can be reduced up to 36%and 15%by properly changing the IWM suspension system parameters.展开更多
Erratum After publication of the original article(Zhu et al.2017),the author has noticed some error with the figure citation in Results and Discussion section,under the title‘VEC model’and‘Impulse response function...Erratum After publication of the original article(Zhu et al.2017),the author has noticed some error with the figure citation in Results and Discussion section,under the title‘VEC model’and‘Impulse response function’.Details are as follows:(1)“Finally we test VEC stability condition,Fig.1 is the AR roots graph,and all the spots are in the unit circle so the model is stable.”展开更多
Static cache partitioning can reduce inter- application cache interference and improve the composite performance of a cache-polluted application and a cache- sensitive application when they run on cores that share the...Static cache partitioning can reduce inter- application cache interference and improve the composite performance of a cache-polluted application and a cache- sensitive application when they run on cores that share the last level cache in the same multi-core processor. In a virtu- alized system, since different applications might run on dif- ferent virtual machines （VMs） in different time, it is inappli- cable to partition the cache statically in advance. This paper proposes a dynamic cache partitioning scheme that makes use of hot page detection and page migration to improve the com- posite performance of co-hosted virtual machines dynami- cally according to prior knowledge of cache-sensitive appli- cations. Experimental results show that the overhead of our page migration scheme is low, while in most cases, the com- posite performance is an improvement over free composition.展开更多
ZnTixFe2-xO4 and ZnTi0.6Fe1.4O4/Carbon nanotubes （ZT0.6F1.4/CNTs） composites were prepared by chemical co-precipitation method. The composition, microstructure, magnetic property, adsorption and photocatalytic activ...ZnTixFe2-xO4 and ZnTi0.6Fe1.4O4/Carbon nanotubes （ZT0.6F1.4/CNTs） composites were prepared by chemical co-precipitation method. The composition, microstructure, magnetic property, adsorption and photocatalytic activity of the prepared samples were characterized by means of modem analytical techniques. The results indicated that ZT0.6F1.4CNTs composites not only held the original special structure and excellent adsorption properties of CNTs, but also had suitable magnetic property and excellent photocatalytic activity. The removal rate of the samples on Rhodamine B （RhB） depended on the adsorption of CNTs and the photocatalytic degradation of ZTo.6F1.4 in the composites. The maximum adsorption amount （qm） of ZT0.6F1.4/CNTs with the mass ratios of ZT0.6F1.4 to CNTs （mz/c）=l was up to 17.153 mg g-t for RhB, its adsorption behavior was in accord with Langmuir model, and its photocatalytic degradation activity on RhB had a positive correlation with the content of ZT0.6F1.4 in the sample. The experimental results indicate that the total removal rate of composite with rnz/c=l on RhB was more than 95% and the composite had good decontamination capability on industrial dye wastewater. In addition, the samples can be recovered conveniently, activated easily and had good performance for recycling.展开更多
基金Supported by Natural Science Foundation of China(Grant Nos.52072051,51705044)Chongqing Municipal Natural Science Foundation of China(Grant No.cstc2020jcyj-msxmX0956)+1 种基金State Key Laboratory of Mechanical System and Vibration(Grant No.MSV202016)State Key Laboratory of Mechanical Transmissions(Grant No.SKLMT-KFKT-201806).
文摘A comparative study of model predictive control(MPC)schemes and robust Hstate feedback control(RSC)method for trajectory tracking is proposed in this paper.The main objective of this paper is to compare MPC and RSC controllers’performance in tracking predefined trajectory under different scenarios.MPC controller is designed based on the simple longitudinal-yaw-lateral motions of a single-track vehicle with a linear tire,which is an approximation of the more realistic model of a vehicle with double-track motion with a non-linear tire mode.RSC is designed on the basis of the same method as adopted for the MPC controller to achieve a fair comparison.Then,three test cases are built in CarSim-Simulink joint platform.Specifically,the verification test is used to test the tracking accuracy of MPC and RSC controller under well road conditions.Besides,the double lane change test with low road adhesion is designed to find the maximum velocity that both controllers can carry out while guaranteeing stability.Furthermore,an extreme curve test is built where the road adhesion changes suddenly,in order to test the performance of both controllers under extreme conditions.Finally,the advantages and disadvantages of MPC and RSC under different scenarios are also discussed.
基金This work is supported by the National Natural Science Foundation of China(Grant No.51805332)the Young Elite Scientists Sponsorship Program funded by the China Society of Automotive Engineers,the Natural Science Foundation of Guangdong Province(Grant No.2018A030310532)the Shenzhen Fundamental Research Fund(Grant No.JCYJ20190808142613246).
文摘Road intersection is one of the most complex and accident-prone traffic scenarios,so it’s challenging for autonomous vehicles(AVs)to make safe and efficient decisions at the intersections.Most of the related studies focus on the solution to a single scenario or only guarantee safety without considering driving efficiency.To address these problems,this study proposed a deep reinforcement learning enabled decision-making framework for AVs to drive through intersections automatically,safely and efficiently.The mapping relationship between traffic images and vehicle operations was obtained by an end-to-end decision-making framework established by convolutional neural networks.Traffic images collected at two timesteps were used to calculate the relative velocity between vehicles.Markov decision process was employed to model the interaction between AVs and other vehicles,and the deep Q-network algorithm was utilized to obtain the optimal driving policy regarding safety and efficiency.To verify the effectiveness of the proposed decision-making framework,the top three accident-prone crossing path crash scenarios at intersections were simulated,when different initial vehicle states were adopted for better generalization capability.The results showed that the developed method could make AVs drive safely and efficiently through intersections in all of the tested scenarios.
基金part of the project "Second Chinese National Arctic Research Expedition" (or CHINARE-2003) supported by the Ministry of Finance of China and organized by the Chinese Arctic and supported by the National Basic Research Program of China (Grant No. G2007CB815903)National Natural Science Foundation of China (Grant Nos. 40321603 and 40676030)Chinese IPY Program (Grant No. 2007―2009)
文摘The late Quaternary ice rafted detritus (IRD) events in the Chukchi Basin, western Arctic Ocean are indications of the provenance of the coarser detritus and ice export events, and also document the evolutionary histories of Beaufort Gyre and the North American Ice Sheet (NAIS). The sediment of core M03 from the Chukchi Basin was selected to study the regional response to the ice export events and the NAIS variability. The stratigraphic framework of M03 was established by a combination of lithological features and downcore color change cycles, AMS14C dating with foraminifera abundance and IRD events. The core was also compared with the adjacent core NWR 5 from the Northwind Ridge area. The core extends back to Marine Isotope Stage (MIS) 7. A sedimentary hiatus of 10―20 ka might occur between 16 to 20 cm core depth. Seven IRD events are distinguished from the studied core and are presented during the early MIS 1, MIS 3, MIS 5 and late MIS 7. These IRD are transported by sea ice and icebergs, which were exported to the Beaufort Sea from the M'Clure Strait Ice Stream, Canadian Arctic Archipelago, and brought to the Chukchi Basin by the Beaufort Gyre.
基金Supported by National Natural Science Foundation of China (Grant Nos.52222215,52072051)Fundamental Research Funds for the Central Universities in China (Grant No.2023CDJXY-025)Chongqing Municipal Natural Science Foundation of China (Grant No.CSTB2023NSCQ-JQX0003)。
文摘The new energy vehicle plays a crucial role in green transportation,and the energy management strategy of hybrid power systems is essential for ensuring energy-efficient driving.This paper presents a state-of-the-art survey and review of reinforcement learning-based energy management strategies for hybrid power systems.Additionally,it envisions the outlook for autonomous intelligent hybrid electric vehicles,with reinforcement learning as the foundational technology.First of all,to provide a macro view of historical development,the brief history of deep learning,reinforcement learning,and deep reinforcement learning is presented in the form of a timeline.Then,the comprehensive survey and review are conducted by collecting papers from mainstream academic databases.Enumerating most of the contributions based on three main directions—algorithm innovation,powertrain innovation,and environment innovation—provides an objective review of the research status.Finally,to advance the application of reinforcement learning in autonomous intelligent hybrid electric vehicles,future research plans positioned as“Alpha HEV”are envisioned,integrating Autopilot and energy-saving control.
基金supported by the National Natural Science Foundation of China (No. 22005216 and 52172241)the General Research Fund of Hong Kong (No. CityU 11308321)Tianjin Research Innovation Project for Postgraduate Students (No.2022BKY130)
文摘Suppression of uncontrollable dendrite growth and water-induced side reactions of Zn metal anodes is crucial for achieving long-lasting cycling stability and facilitating the practical implementations of aqueous Zn-metal batteries.To address these challenges,we report in this study a functional nitro-cellulose interfacial layer(NCIL)on the surface of Zn anodes enlightened by a nitro-coordination chemistry strategy.The NCIL exhibits strong zincophilicity and superior coordination capability with Zn^(2+)due to the highly electronegative and highly nucleophilic nature of the nitro functional group.This characteristic facilitates a rapid Zn-ion desolvation process and homogeneous Zn plating,effectively preventing H_(2) evolution and dendrite formation.Additionally,the negatively charged surface of NCIL acts as a shield,repelling SO_(4)^(2-)anions and inhibiting corrosive reactions on the Zn surface.Remarkably,reversible and stable Zn plating/stripping is achieved for over 5100 h at a current density of 1 mA cm^(-2),which is nearly 30 times longer than that of bare Zn anodes.Furthermore,the Zn/V_(2)O_(5) full cells with the functional interface layer deliver a high-capacity retention of 80.3%for over 10,000 cycles at 5 A g^(-1).This research offers valuable insights for the rational development of advanced protective interface layers in order to achieve ultra-long-lifeZnmetal batteries.
基金supported by the National Natural Science Foundation of China(Nos.52170156,52250056,and 52293442)the Shenzhen Science and Technology Program(No.KQTD20190929172630447)。
文摘Effective monitoring and management of microbial risk factors in wastewater treatment plants(WWTPs)effluents require a comprehensive investigation of these risks.A global survey on microbial risk factors in WWTP effluents could reveal important insights into their risk features.This study aims to explore the abundance and types of antibiotic resistance genes(ARGs),virulence factor genes(VFGs),the vector of ARG/VFG,and dominant pathogens in global WWTP effluents.We collected 113 metagenomes of WWTP effluents from the Sequence Read Archive of the National Center for Biotechnology Information and characterized the microbial risk factors.Our results showed that multidrug resistance was the dominant ARG type,while offensive virulence factors were the most abundant type of VFGs.The most dominant types of ARGs in the vector of plasmid and phage were both aminoglycoside resistance,which is concerning as aminoglycosides are often a last resort for treating multi-resistant infections.Acinetobacter baumannii was the most dominant pathogen,rather than Escherichia coli,and a weak negative correlation between Escherichia coli and two other dominant pathogens(Acinetobacter baumannii and Bacteroides uniformis)suggests that using Escherichia coli as a biological indicator for all pathogens in WWTP effluents may not be appropriate.The Getah virus was the most dominant virus found in global WWTP effluents.Our study presents a comprehensive global-scale investigation of microbial risk factors in WWTP effluents,providing valuable insights into the potential risks associated with WWTP effluents and contributing to the monitoring and control of these risks.
基金This study is supported by the National Natural Science Foundation of China under Grant 51805028,in part by the Young Elite Scientists Sponsorship Program funded by the China Society of Automotive Engineers,and in part by the Beijing Institute of Technology Research Fund Program for Young Scholars.
文摘The in-wheel motor(IWM)-driven electric vehicles(EVs)attract increasing attention due to their advantages in dimensions and controllability.The majority of the current studies on IWM are carried out with the assumption of an ideal actuator,in which the coupling effects between the non-ideal IWM and vehicle are ignored.This paper uses the braking process as an example to investigate the longitudinal-vertical dynamics of IWM-driven EVs while considering the mechanical-electrical coupling effect.First,a nonlinear switched reluctance motor model is developed,and the unbalanced electric magnetic force(UEMF)induced by static and dynamic mixed eccentricity is analyzed.Then,the UEMF is decomposed into longitudinal and vertical directions and included in the longitudinal-vertical vehicle dynamics.The coupling dynamics are demonstrated under different vehicle braking scenarios;numerical simulations are carried out for various road grades,road friction,and vehicle velocities.A novel dynamics vibration absorbing system is adopted to improve the vehicle dynamics.Finally,the simulation results show that vehicle vertical dynamic performance is enhanced.
基金supported by the National Natural Science Foundation of China(Grant No.52272421).
文摘Driver distraction has been deemed a major cause of traffic accidents.However,drivers’brain response activities to different distraction types have not been well investigated.The purpose of this study is to investigate the response of electroencephalography(EEG)activities to different distraction tasks.In the conducted simulation tests,three secondary tasks(i.e.,a clock task,a 2-back task,and a navigation task)are designed to induce different types of driver distractions.Twenty-four participants are recruited for the designed tests,and differences in drivers’brain response activities concerning distraction types are investigated.The results show that the differences in comprehensive distraction are more significant than that in single cognitive distraction.Friedman test and post hoc two-tailed Nemenyi test are conducted to further identify the differences in band activities among brain regions.The results show that the theta energy in the frontal lobe is significantly higher than that in other brain regions in distracted driving,whereas the alpha energy in the temporal lobe significantly decreases compared to other brain regions.These results provide theoretical references for the development of distraction detection systems based on EEG signals.
基金Supported by the National Natural Science Foundation of China,No.30270078
文摘AIM: To construct a recombinant strain which expresses BabA of Helicobacter pylori(H pylori) and to study the immunogenicity of BabA.METHODS: BabA2 DNA was amplified by PCR and inserted into the prokaryotie expression vector pET-22b (+) and expressed in the BL21 (DE3) E.coli strain. Furthermore,BabA immunogenicity was studied by animal test.RESULTS: DNA sequence analysis showed the sequence of BabA2 DNA was the same as the one published by GenBank.The BabA recombinant protein accounted for 34.8% of the total bacterial protein. The serum from H pylori infected patients and Balb/c miced immunized with BabA itself could recognize rBabA.CONCLUSION: BabA recombinant protein may be an potential vaccine for control and treatment of Hpyloriinfection.
基金supported by the National Natural Science Foundation of China(Grant Nos.52209108 and 52079034)Sichuan Science and Technology Program(Grant No.2023YFQ0021)+1 种基金the Natural Science Foundation of Heilongjiang Province,China(Grant No.LH2023E058)China Postdoctoral Science Foundation(Grant No.2022M720948)。
文摘Large-head variable-amplitude pump turbines(PTs) encounter serious transient hydraulic instability issues. To explore the evolution mechanisms of pressure fluctuations(PFs) and flow patterns inside large-head variable-amplitude PTs, the load rejection process(LRP) was investigated using a one-and three-dimensional coupled flow simulation approach. The temporal,spatial, and frequency characteristics of the fluctuating pressures were analyzed for four monitoring points using a combined time-frequency analysis approach. The results indicated that PFs during the LRP of large-head variable-amplitude PTs had a new fluctuation frequency component related to Dean vortices(DVs) in the volute, in addition to the common fluctuation frequency components related to rotor-stator interaction phenomena and local backflow vortices near the impeller inlet. The PF frequency component existed throughout the LRP and had a significant influence on the transient maximum pressure at the volute end. This study provides a useful theoretical guide for the design and optimization of large-head variable-amplitude PTs.
基金the National Natural Science Foundation of China,No.30270078
文摘AIM: To express Hsp60 protein of H pylori by a constructed vector and to evaluate its immunogenicity.METHODS: Hsp60 DNA was amplified by PCR and inserted into the prokaryotie expression vector pET-22b (+), which was transformed into BL21 (DE3) E. coli strain to express recombinant protein. Immunogenicity of expressed Hsp60 protein was evaluated with animal experiments.RESULTS: DNA sequence analysis showed Hsp60 DNA was the same as GenBank's research. Hsp60 recombinant protein accounted for 27.2 % of the total bacterial protein,and could be recognized by the serum from H pylori infected patients and Balb/c mice immunized with Hsp60 itself.CONCLUSION: Hsp60 recombinant protein might become a potential vaccine for controlling and treating H pylori infection.
基金This work was supported by the Key Plan of National Social Science Foundation of China under the Grant 14ZDA044.
文摘Background:Bitcoin,the most innovate digital currency as of now,created since 2008,even through experienced its ups and downs,still keeps drawing attentions to all parts of society.It relies on peer-to-peer network,achieved decentralization,anonymous and transparent.As the most representative digital currency,people curious to study how Bitcoin’price changes in the past.Methods:In this paper,we use monthly data from 2011 to 2016 to build a VEC model to exam how economic factors such as Custom price index,US dollar index,Dow jones industry average,Federal Funds Rate and gold price influence Bitcoin price.Result:From empirical analysis we find that all these variables do have a long-term influence.US dollar index is the biggest influence on Bitcoin price while gold price influence the least.Conclusion:From our result,we conclude that for now Bitcoin can be treated as a speculative asset,however,it is far from being a proper credit currency.
基金This work was supported by the Scientific Research Foundation of Zhejiang Sci-Tech University(19212450-Y).
文摘In the research for the safe and efficiently antibacterial cotton fabrics to minimize risk for human health,an organic–inorganic hybrid material of ZnO nanoparticles(NPs)and quaternary ammonium salt(QAS)was employed to modify cotton fabrics by a dipping–padding–drying method.The synergistic effects of ZnO NPs and QAS on the structure and antibacterial properties of cotton fabrics were studied in detail.Results displayed that the QAS and ZnO NPs were immobilized firmly in cotton fabric by the formation of chemical covalent bonds and silica gel structure.ZnO/QAS/cotton had a good inhibitory effect on the growth of E.coli and S.aureus,with superior antibacterial efficiency of>99.99%.ZnO/QAS/cotton preserved good mechanical property,water absorbability,and limpness.We also provided a detailed analysis of antibacterial mechanism for the hybrid materials.The contact mechanism and the Zn2+release were considered as the main mechanisms for the ZnO/QAS/cotton,while the reactive oxygen species(ROS)generation only had a little contribution to the antibacterial activity.In short,the excellent integrated properties endowed the hybrid cotton fabrics as potential application in many fields,like healthcare,food packaging.
基金The work was supported by the Scientific Research Foundation of Zhejiang Sci-Tech University(19212450-Y).
文摘The catalytic conversion of biomass platform chemicals using abundant non-noble metal nanocatalysts is a challenging topic.Here,high-density cobalt oxide nanoparticles loaded on biomass-derived porous N-doped carbon(NC)was fabricated by a tandem hydrothermal pyrolysis and mild nitrate decomposition process,which is a green and cheap preparation method.The Co_(3)O_(4) nanoparticles with the average size of 12 nm were uniformly distributed on the porous NC.The nanocomposites also possessed large surface area,high N content,good dispersibility in isopropanol,and furfural absorbability.Due to these characteristics,the novel cobalt nanocatalyst exhibited high catalytic activity for producing furfuryl alcohol,yielding 98.7%of the conversion and 97.1%of the selectivity at 160℃ for 6 h under 1 bar H2.The control experiments implied that both direct hydrogenation and transfer hydrogenation pathways co-existed in the hydrogenation reaction.The excellent catalytic activity of Co_(3)O_(4)@NC was attributed to the cooperative effects of porous NC and Co_(3)O_(4) nanoparticles.This approach provides a new idea to design effective high-density nonnoble metal oxide nanocatalysts for hydrogenation reactions,which can make full use of sustainable natural biomass.
基金supported by the Funds for Creative Research Group of NSFC (No.21621005)。
文摘Nickel (hydr)oxide (NiOH) is known to be good co-catalyst for the photoelectrochemical oxidation of water,and for the photocatalytic oxidation of organics on different semiconductors.Herein we report a greatly improved activity of Bi_(2)MoO_(6)(BMO) by nickel hexammine perchlorate (NiNH).Under visible light,phenol oxidation on BMO was slow.After NiNH,NiOH,and Ni^(2+)loading,a maximum rate of phenol oxidation increased by factors of approximately 16,8.8,and 4.7,respectively.With a BMO electrode,all catalysts inhibited O_(2)reduction,enhanced water (photo-)oxidation,and facilitated the charge transfer at solidliquid interface,respectively,the degree of which was always NiNH>NiOH>Ni^(2+).Solid emission spectra indicated that all catalysts improved the charge separation of BMO,the degree of which also varied as NiNH>NiOH>Ni^(2+).Furthermore,after a phenol-free aqueous suspension of NiNH/BMO was irradiated,there was a considerable Ni(Ⅲ) species,but a negligible NH_(2)radical.Accordingly,a plausible mechanism is proposed,involving the hole oxidation of Ni(Ⅱ) into Ni(Ⅳ),which is reactive to phenol oxidation,and hence promotes O_(2)reduction.Because NH_(3)is a stronger ligand than H_(2)O,the Ni(Ⅱ) oxidation is easier for Ni(NH_(3))6+than for Ni(H_(2)O)6+.This work shows a simple route how to improve BMO photocatalysis through a co-catalyst.
基金This study was supported by Young Scientists Fund(Grant No.51805028)Postdoctoral Research Foundation of China(Grant No.BX201600017).
文摘Distributed-drive electric vehicles(EVs)replace internal combustion engine with multiple motors,and the novel configura-tion results in new dynamic-related issues.This paper studies the coupling effects between the parameters and responses of dynamic vibration-absorbing structures(DVAS)for EVs driven by in-wheel motors(IWM).Firstly,a DVAS-based quarter suspension model is developed for distributed-drive EVs,from which nine parameters and five responses are selected for the coupling effect analysis.A two-stage global sensitivity analysis is then utilized to investigate the effect of each parameter on the responses.The control of the system is then converted into a multiobjective optimization problem with the defined system parameters being the optimization variables,and three dynamic limitations regarding both motor and suspension subsystems are taken as the constraints.A particle swarm optimization approach is then used to either improve ride comfort or mitigate IWM vibration,and two optimized parameter sets for these two objects are provided at last.Simulation results provide in-depth conclusions for the coupling effects between parameters and responses,as well as a guideline on how to design system parameters for contradictory objectives.It can be concluded that either passenger comfort or motor lifespan can be reduced up to 36%and 15%by properly changing the IWM suspension system parameters.
文摘Erratum After publication of the original article(Zhu et al.2017),the author has noticed some error with the figure citation in Results and Discussion section,under the title‘VEC model’and‘Impulse response function’.Details are as follows:(1)“Finally we test VEC stability condition,Fig.1 is the AR roots graph,and all the spots are in the unit circle so the model is stable.”
文摘Static cache partitioning can reduce inter- application cache interference and improve the composite performance of a cache-polluted application and a cache- sensitive application when they run on cores that share the last level cache in the same multi-core processor. In a virtu- alized system, since different applications might run on dif- ferent virtual machines （VMs） in different time, it is inappli- cable to partition the cache statically in advance. This paper proposes a dynamic cache partitioning scheme that makes use of hot page detection and page migration to improve the com- posite performance of co-hosted virtual machines dynami- cally according to prior knowledge of cache-sensitive appli- cations. Experimental results show that the overhead of our page migration scheme is low, while in most cases, the com- posite performance is an improvement over free composition.
基金the National Nature Science Foundation of China (21071125) for financial support
文摘ZnTixFe2-xO4 and ZnTi0.6Fe1.4O4/Carbon nanotubes （ZT0.6F1.4/CNTs） composites were prepared by chemical co-precipitation method. The composition, microstructure, magnetic property, adsorption and photocatalytic activity of the prepared samples were characterized by means of modem analytical techniques. The results indicated that ZT0.6F1.4CNTs composites not only held the original special structure and excellent adsorption properties of CNTs, but also had suitable magnetic property and excellent photocatalytic activity. The removal rate of the samples on Rhodamine B （RhB） depended on the adsorption of CNTs and the photocatalytic degradation of ZTo.6F1.4 in the composites. The maximum adsorption amount （qm） of ZT0.6F1.4/CNTs with the mass ratios of ZT0.6F1.4 to CNTs （mz/c）=l was up to 17.153 mg g-t for RhB, its adsorption behavior was in accord with Langmuir model, and its photocatalytic degradation activity on RhB had a positive correlation with the content of ZT0.6F1.4 in the sample. The experimental results indicate that the total removal rate of composite with rnz/c=l on RhB was more than 95% and the composite had good decontamination capability on industrial dye wastewater. In addition, the samples can be recovered conveniently, activated easily and had good performance for recycling.
