Serving as a promising alternative to liquid electrolyte in the application of portable and wearable devices,gel polymer electrolytes(GPEs)are expected to obtain more preferable properties rather than just be satisfie...Serving as a promising alternative to liquid electrolyte in the application of portable and wearable devices,gel polymer electrolytes(GPEs)are expected to obtain more preferable properties rather than just be satisfied with the merits of high safety and deformability.Here,an easy-operated method is employed to fabricate cross-linked composite polymer membranes used for GPEs assisted by UV irradiation,in which N-doped carbon quantum dots(N-CQDs)and TiO2are introduced as photocatalysts and additives to improve the performances of GPEs.Specifically,N-CQDs participate as a cross-linker to construct the inner porous structure,and TiO2nanoparticles serve as a stabilizer to improve the electrochemical stability of GPEs under high voltage(3.5 V).The excellent thermal and mechanical stability of the membrane fabricated in this work guarantee the safety of the supercapacitors(SCs).This GPE based SC not only exhibits prominent rate performance(105%capacitance retention at the current density of 40A g^(-1))and cyclic stability(85%at 1 A g^(-1)under 3.5 V after 20,000 cycles),but also displays remarkable energy density(42.88 Wh kg^(-1))with high power density(19.3 k W kg^(-1)).Moreover,the superior rate and cycling performances of the as-prepared GPE based flexible SCs under flat and bending state confirm the feasibility of its application in flexible energy storage devices.展开更多
Lithium(Li)metal batteries(LMBs)are widely regarded as the ultimate choice for the next generation of high-energy–density batteries.However,the uncontrollable growth of Li dendrites formed by inhomogeneous deposition...Lithium(Li)metal batteries(LMBs)are widely regarded as the ultimate choice for the next generation of high-energy–density batteries.However,the uncontrollable growth of Li dendrites formed by inhomogeneous deposition seriously hinders its commercialization.Although many studies have achieved significant results in inhibiting the formation of Li dendrites,it is still impossible to eradicate them completely.Therefore,regulating the deposition behavior,such as the growth direction of unevenly deposited Li,is preferable to unilaterally suppressing them in some cases.Here we report a structured anode that can confine the deposited Li within holes and tune it to become vertical-up/horizontal-centripetal mixed growth mode by optimizing the electric field/Li^(+)concentration gradient.The Li^(+) adsorbed by the poly(amic acid)(PAA)insulating layer coated on the anode surface can form the Li^(+)concentration gradient pointing to the center of the hole.Combined with the special electric field formed by the hole structure,it is favorable for the Li^(+)to move into the vertically arrayed holes and simultaneously deposit on the bottom and walls.Furthermore,both in-situ and ex-situ observations confirm that the growth mode is changed and the Li deposition morphology is denser,which can greatly delay capacity fading and prolong cycle life in both liquid and quasi-solid-state LMBs.All the results show that the novel anode provides a new perspective for deep research into solid-state LMBs.展开更多
In this paper,a trusted multi-task distribution mechanism for Internet of Vehicles based on smart contract is proposed to improve the security and efficiency for the task distribution in Internet of Vehicles.Firstly,a...In this paper,a trusted multi-task distribution mechanism for Internet of Vehicles based on smart contract is proposed to improve the security and efficiency for the task distribution in Internet of Vehicles.Firstly,a three-tier trusted multi-task distribution framework is presented based on smart contract.The smart contract will be triggered by the task request.As the important part of the smart contract,the task distribution algorithm is stored on the blockchain and run automatically.In the process of the task distribution,the cost of the task distribution and the system stability play a critical role.Therefore,the task distribution problem is formulated to minimize the cost of the task distribution whilst maintaining the stability of the system based on Lyapunov theorem.Unfortunately,this problem is a mixed integer nonlinear programming problem with NP-hard characteristics.To tackle this,the optimization problem is decomposed into two sub problems of computing resource allocation and task distribution decision,and an effective task distribution algorithm is proposed.Simulation results show that the proposed algorithm can effectively improves system performance.展开更多
Most gear fault diagnosis(GFD)approaches su er from ine ciency when facing with multiple varying working conditions at the same time.In this paper,a non-negative matrix factorization(NMF)-theoretic co-clustering strat...Most gear fault diagnosis(GFD)approaches su er from ine ciency when facing with multiple varying working conditions at the same time.In this paper,a non-negative matrix factorization(NMF)-theoretic co-clustering strategy is proposed specially to classify more than one task at the same time using the high dimension matrix,aiming to o er a fast multi-tasking solution.The short-time Fourier transform(STFT)is first used to obtain the time-frequency features from the gear vibration signal.Then,the optimal clustering numbers are estimated using the Bayesian information criterion(BIC)theory,which possesses the simultaneous assessment capability,compared with traditional validity indexes.Subsequently,the classical/modified NMF-based co-clustering methods are carried out to obtain the classification results in both row and column tasks.Finally,the parameters involved in BIC and NMF algorithms are determined using the gradient ascent(GA)strategy in order to achieve reliable diagnostic results.The Spectra Quest’s Drivetrain Dynamics Simulator gear data sets were analyzed to verify the e ectiveness of the proposed approach.展开更多
A new continuum damage mechanics model for fretting fatigue life prediction is established. In this model, the damage evolution rate is described by two kinds of quantities. One is associated with the cyclic stress ch...A new continuum damage mechanics model for fretting fatigue life prediction is established. In this model, the damage evolution rate is described by two kinds of quantities. One is associated with the cyclic stress characteristics obtained by the finite element （FE） analysis, and the other is associated with the material fatigue property identified from the fatigue test data of standard specimens. The wear is modeled by the energy wear law to simulate the contact geometry evolution. A two-dimensional （2D） plane strain FE implementation of the damage mechanics model and the energy wear model is presented in the platform of ABAQUS to simulate the evolutions of the fatigue damage and the wear scar. The effect of the specimen thickness is also investigated. The predicted results of the crack initiation site and the fretting fatigue life agree well with available experimental data. Comparisons are made with the critical plane Smith- Watson-Topper （SWT） method.展开更多
A superamphiphobic(SAP)surface was fabricated by electrodepositing Cu-Ni micro-nano particles on aluminum substrate and modifying via 1 H,1 H,2 H,2 Hperfluorodecyltrimethoxysilane.Scanning electron microscopy,X-ray di...A superamphiphobic(SAP)surface was fabricated by electrodepositing Cu-Ni micro-nano particles on aluminum substrate and modifying via 1 H,1 H,2 H,2 Hperfluorodecyltrimethoxysilane.Scanning electron microscopy,X-ray diffraction,energydispersive X-ray spectroscopy,and Fourier-transform infrared spectroscopy were employed to investigate the morphology and chemical composition.The results showed that the SAP surface had three-dimensional micro-nano structures and exhibited a maximum water contact angle of 160.0°,oil contact angle of 151.6°,a minimum water slide angle of 0°and oil slide angle of 9°.The mechanical strength and chemical stability of the SAP surface were tested further.The experimental results showed that the SAP surface presented excellent resistance to wear,prominent acid-resistance and alkali-resistance,self-cleaning and anti-fouling properties.展开更多
Gear fault diagnosis technologies have received rapid development and been effectively implemented in many engineering applications.However,the various working conditions would degrade the diagnostic performance and m...Gear fault diagnosis technologies have received rapid development and been effectively implemented in many engineering applications.However,the various working conditions would degrade the diagnostic performance and make gear fault diagnosis(GFD)more and more challenging.In this paper,a novel model parameter transfer(NMPT)is proposed to boost the performance of GFD under varying working conditions.Based on the previous transfer strategy that controls empirical risk of source domain,this method further integrates the superiorities of multi-task learning with the idea of transfer learning(TL)to acquire transferable knowledge by minimizing the discrepancies of separating hyperplanes between one specific working condition(target domain)and another(source domain),and then transferring both commonality and specialty parameters over tasks to make use of source domain samples to assist target GFD task when sufficient labeled samples from target domain are unavailable.For NMPT implementation,insufficient target domain features and abundant source domain features with supervised information are fed into NMPT model to train a robust classifier for target GFD task.Related experiments prove that NMPT is expected to be a valuable technology to boost practical GFD performance under various working conditions.The proposed methods provides a transfer learning-based framework to handle the problem of insufficient training samples in target task caused by variable operation conditions.展开更多
Vaccine is a principal and highly cost-effective medical method on controlling infectious diseases and improving population health.Various vaccines are eagerly needed in the low-income countries along the Belt&Roa...Vaccine is a principal and highly cost-effective medical method on controlling infectious diseases and improving population health.Various vaccines are eagerly needed in the low-income countries along the Belt&Road.With the good quality to reach WHO prequalification standard,and the abundant capacity to fulfill the demand from market abroad,upon the platform of China-proposed"the Belt&Road Initiative",the vaccines manufactured in China are exporting to countries worldwide.The independent innovative vaccines'R&D system,which fruited a series of innovative infectious diseases vaccines(EV71 vaccine,sIPV,HEV,Ebola vaccine,etc.)to be launched in Chinese market,indicates that China has developed rapidly from"a great vaccine-production country"to"a powerful vaccine-innovation country".The implementation of National Innovation-driven Development Strategy would further push forward the developm ent and internationalization process of Chinese innovative vaccines.Therefore,the China-invented vaccines will make an important role in the prevention and control of infectious disease in various countries and become one of the most powerful weapons in fighting the global epidemic event in the future.展开更多
This work reported a facile approach to surface oxygen vacancy(O_(v))-enriched urchin-like TiO_(2) microparticles(U-TiO_(2)),which were highly effective and durable in catalyzing selective nitrate reduction to ammonia...This work reported a facile approach to surface oxygen vacancy(O_(v))-enriched urchin-like TiO_(2) microparticles(U-TiO_(2)),which were highly effective and durable in catalyzing selective nitrate reduction to ammonia(NOgRR),Specifically,the U-TiO_(2)delivered a mass activity of 1.15 min^(-1)mg^(-1)calyst.a low yield of toxic NO_(2)^(-)-N intermediate(≤0.4mg/L)and an exceptional high NH_(3)^(-)-N selectivity of 98.1%in treating 22.5 mg/L of NO_(3)^(-)-N under a potential of-0.60V vs.RHE,outperforming most of the reported oxidebased catalysts.When comparing the performance of U-TiO_(2)with that of the solid amorphous TiO_(2) counterpart(A-TiO_(2))that had close particle size but more O_(v) on surfaces,we identified that the O_(v) was the reactive sites,but rather than its content,the NO_(3)RR kinetics were primarily limited by the electron and mass transfer at U-TiO_(2)/water interfaces.Accordingly,the superior performance of U-TiO_(2)to A-TiO_(2)could be ascribed to the hierarchical urchin-like structure in U-TiO_(2).The in-situ DEMS test revealed that the NO_(3)RR on U-TiO_(2)followed a pathway of ^(*)NO_(3)^(-)→^(*)NO_(2)^(-)→^(*)NO→^(*)N→^(*)NH^(-)→^(*)NH_(2)→^(*)NH_(3).We also demonstrated that the U-TiO_(2) could keep its robust performance under a wide NO_(3)^(-)-N concentration range and in the presence of some co-existing ions(such as Ca^(2+),Cl^(-),Mg^(2+)).However,the presence of humic acid and CO_(3)^(2-) in water slowed down the NO_(3)RR on U-TiO_(2).This work provides a more fundamental insight into the O_(v)-driven NO_(3)RR process on TiO_(2),which should benefit for the development of eficient TiO_(2)-based catalvsts.展开更多
Safety issues induced by infinite anode volume change and uncontrolled lithium(Li)dendrite growth have become the biggest obstacle to the practical application of Li metal batteries.In addition,the tra-ditional rollin...Safety issues induced by infinite anode volume change and uncontrolled lithium(Li)dendrite growth have become the biggest obstacle to the practical application of Li metal batteries.In addition,the tra-ditional rolling method makes it difficult to manufacture thin Li foil with high mechanical strength and low Li content.Herein,a three-dimensional(3D)lithophilic carbon paper/copper(Cu)current collector hybrid anode with ultra-low Li metal content is prepared by a hot-pressing method.The highly re-versible and stable lithiophilic layer LiC_(x) formed in situ by heating/pressing treatment provides abun-dant nucleation sites and reduces the Li nucleation overpotential,thereby effectively suppressing Li den-drite growth.Moreover,the volume change and pulverization problems of Li metal anode during depo-sition/stripping also can be accommodated by the 3D skeleton.The optimization effect has been directly confirmed by in-situ optical and ex-situ scanning electron microscope observation.Therefore,highly sta-ble performance(158.4 mA h g^(-1) at 2 C after 200 cycles with a capacity retention of 95.24%)in Li@LCP-Cu||NCM811 coin cell can be achieved.Furthermore,the solid-state battery assembled with the hybrid anode,poly(vinylidene fluoride)(PVDF)-based polymer electrolyte and polyethylene oxide(PEO)interface functional layer also exhibits the best electrochemical and safety performance,which also proves that the Li@LCP-Cu anode has great potential for application in solid-state batteries.展开更多
A new Precise Point Positioning(PPP)service,called the PPP-B2b service,has been implemented in the BeiDou-3 Navigation Satellite System(BDS-3),which brings new opportunities for time transfer.However,the solution usin...A new Precise Point Positioning(PPP)service,called the PPP-B2b service,has been implemented in the BeiDou-3 Navigation Satellite System(BDS-3),which brings new opportunities for time transfer.However,the solution using the traditional PPP method with the PPP-B2b correction still absorbs some unknown errors and needs reconverging when there exist abnormal data.We developed a new receiver clock model to improve PPP time transfer using the PPP-B2b correction.The traditional PPP time transfers using PPP-B2b with BDS-3,Global Positioning System(GPS),and BDS-3/GPS(Scheme1)are compared with the corresponding time transfer with the proposed clock model(Scheme2).The results show that GPS-only PPP is not recommended because of low accuracy of 2 ns.BDS-3 or BDS-3/GPS PPP time transfers in Scheme1 can realize about 0.2 ns accuracy.When the new clock model is applied,the accuracy can be improved by up to 45%and 39.8%for BDS-3 and BDS-3/GPS PPP,respectively.The proposed clock model can signifcantly improve the short-term frequency stability by 57.4%,but less for the long-term stability.展开更多
As a globally popular leafy vegetable and a representative plant of the Asteraceae family,lettuce has great economic and academic significance.In the last decade,high-throughput sequencing,phenotyping,and other multi-...As a globally popular leafy vegetable and a representative plant of the Asteraceae family,lettuce has great economic and academic significance.In the last decade,high-throughput sequencing,phenotyping,and other multi-omics data in lettuce have accumulated on a large scale,thus increasing the demand for an integrative lettuce database.Here,we report the establishment of a comprehensive lettuce database,LettuceGDB(https://www.lettucegdb.com/).As an omics data hub,the current LettuceGDB includes two reference genomes with detailed annotations;re-sequencing data from over 1000 lettuce varieties;a collection of more than 1300 worldwide germplasms and millions of accompanying phenotypic records obtained with manual and cutting-edge phenomics technologies;re-analyses of 256 RNA sequencing datasets;a complete miRNAome;extensive metabolite information for representative varieties and wild relatives;epigenetic data on the genome-wide chromatin accessibility landscape;and various lettuce research papers published in the last decade.Five hierarchically accessible functions(Genome,Genotype,Germplasm,Phenotype,and O-Omics)have been developed with a user-friendly interface to enable convenient data access.Eight built-in tools(Assembly Converter,Search Gene,BLAST,JBrowse,Primer Design,Gene Annotation,Tissue Expression,Literature,and Data)are available for data downloading and browsing,functional gene exploration,and experimental practice.A community forum is also available for information sharing,and a summary of current research progress on different aspects of lettuce is included.We believe that LettuceGDB can be a comprehensive functional database amenable to data mining and database-driven exploration,useful for both scientific research and lettuce breeding.展开更多
Object contour plays an important role in fields such as semantic segmentation and image classification. However, the extraction of contour is a difficult task, especially when the contour is incomplete or unclosed. I...Object contour plays an important role in fields such as semantic segmentation and image classification. However, the extraction of contour is a difficult task, especially when the contour is incomplete or unclosed. In this paper, the existing contour detection approaches are reviewed and roughly divided into three categories： pixel-based, edge-based, and region-based. In addition, since the traditional contour detection approaches have achieved a high degree of sophistication, the deep convolutional neural networks （DCNNs） have good performance in image recognition, therefore, the DCNNs based contour detection approaches are also covered in this paper. Moreover, the future development of contour detection is analyzed and predicted.展开更多
Lithium （Li） metal has been considered as the most attractive anode materials for Li-ion batteries （LIBs） due to its high theoretic specific capacity. The formation of unstable solid electrolyte interphase （SEI）...Lithium （Li） metal has been considered as the most attractive anode materials for Li-ion batteries （LIBs） due to its high theoretic specific capacity. The formation of unstable solid electrolyte interphase （SEI） and dendritic Li on the metal anode, however, hindered its practical application. Herein, to address the issues, a Li-free electrode with ultrathin Al2O3 coated on reduced graphene oxide （rGO） membrane that covers a Cu foil current collector was developed. The composite electrode exhibits excellent interfacial protection of lithium metal deposited between Cu foil and rGO electrochemically. Firstly, it affords good Li^＋ permeability from the electrolyte. Secondly, the ultrathin Al2O3 has sufficient mechanical strength to inhibit the penetration of Li dendrite. Li metal was observed uniformly deposited between rGO membrane and Cu collector, and stable cycle performance of Li plating/stripping with Coulombic efficiency of ~ 91.75% at the lOOth cycle is achieved in organic carbonate electrolyte without any additives.展开更多
Sub-100 nm hollow carbon nanospheres with thin shells are highly desirable anode materials for energy storage applications. However, their synthesis remains a great challenge with conventional strategies. In this work...Sub-100 nm hollow carbon nanospheres with thin shells are highly desirable anode materials for energy storage applications. However, their synthesis remains a great challenge with conventional strategies. In this work, we demonstrate that hollow carbon nanospheres of unprecedentedly small sizes （down to - 32.5 nm and with thickness of - 3.9 nm） can be produced on a large scale by a templating process in a unique reverse micelle system. Reverse micelles enable a spatially confined Stober process that produces uniform silica nanospheres with significantly reduced sizes compared with those from a conventional Stober process, and a subsequent well-controlled sol-gel coating process with a resorcinol-formaldehyde resin on these silica nanospheres as a precursor of the hollow carbon nanospheres. Owing to the short diffusion length resulting from their hollow structure, as well as their small size and microporosity, these hollow carbon nanospheres show excellent capacity and cycling stability when used as anode materials for lithium/sodium-ion batteries.展开更多
An approach based on continuum damage mechanics to fatigue life prediction for structures is proposed. A new fatigue damage evolution equation is developed, in which the pa- rameters are obtained in a simple way with ...An approach based on continuum damage mechanics to fatigue life prediction for structures is proposed. A new fatigue damage evolution equation is developed, in which the pa- rameters are obtained in a simple way with reference to the experimental results of fatigue tests on standard specimens. With the utilization of APDL language on the ANSYS platform, a finite element implementation is presented to perform coupling operation on damage evolution of mate- rial and stress redistribution. The fatigue lives of some notched specimens and a Pitch-change-link are predicted by using the above approach. The calculated results are validated with experimental data.展开更多
A large number of pharmaceuticals and personal care products(PPCPs)persist in wastewater,and the consumption of PPCPs for COVID-19 control and prevention has sharply increased during the pandemic.This study investigat...A large number of pharmaceuticals and personal care products(PPCPs)persist in wastewater,and the consumption of PPCPs for COVID-19 control and prevention has sharply increased during the pandemic.This study investigated the occurrence,removal efficiency,and risk assessment of six typical PPCPs commonly used in China in two wastewater treatment plants(WWTPs).Ribavirin(RBV)is an effective pharmaceutical for severely ill patients with COVID-19,and the possible biodegradation pathway of RBV by activated sludge was discovered.The experimental results showed that PPCPs were detected in two WWTPs with a detection rate of 100%and concentrations ranging between 612 and 2323 ng L^(-1).The detection frequency and concentrations of RBV were substantially higher,with a maximum concentration of 314 ng L^(-1).Relatively high pollution loads were found for the following PPCPs from influent:ibuprofen>ranitidine hydrochloride>RBV>ampicillin sodium>clozapine>sulfamethoxazole.The removal efficiency of PPCPs was closely related to adsorption and biodegradation in activated sludge,and the moving bed biofilm reactor(MBBR)had a higher removal capacity than the anoxic-anaerobic-anoxicoxic(AAAO)process.The removal efficiencies of sulfamethoxazole,ampicillin sodium,ibuprofen,and clozapine ranged from 92.21%to 97.86%in MBBR process and were relatively low,from 61.82%to 97.62%in AAAO process,and the removal of RBV and ranitidine hydrochloride were lower than 42.96%in both MBBR and AAAO processes.The discrepancy in removal efficiency is caused by temperature,hydrophilicity,and hydrophobicity of the compound,and acidity and alkalinity.The transformation products of RBV in activated sludge were detected and identified,and the biodegradation process of RBV could be speculated as follows:first breaks into TCONH_(2) and an oxygen-containing five-membered heterocyclic ring under the nucleosidase reaction,and then TCONH_(2) is finally formed into TCOOH through amide hydrolysis.Aquatic ecological risks based on risk quotient(RQ)assessment showed that PPCPs had high and medium risks in the influent,and the RQ values were all reduced after MBBR and AAAO treatment.Ranitidine hydrochloride and clozapine still showed high and medium risks in the effluent,respectively,and thus presented potential risks to the aquatic ecosystem.展开更多
基金funding supports from the Natural Science Basis Research Plan in Shaanxi Province of China(2019JLZ-10)the Independent Research Project of National Key Laboratory of Electrical Insulation and Power Equipment(EIPE19111)。
文摘Serving as a promising alternative to liquid electrolyte in the application of portable and wearable devices,gel polymer electrolytes(GPEs)are expected to obtain more preferable properties rather than just be satisfied with the merits of high safety and deformability.Here,an easy-operated method is employed to fabricate cross-linked composite polymer membranes used for GPEs assisted by UV irradiation,in which N-doped carbon quantum dots(N-CQDs)and TiO2are introduced as photocatalysts and additives to improve the performances of GPEs.Specifically,N-CQDs participate as a cross-linker to construct the inner porous structure,and TiO2nanoparticles serve as a stabilizer to improve the electrochemical stability of GPEs under high voltage(3.5 V).The excellent thermal and mechanical stability of the membrane fabricated in this work guarantee the safety of the supercapacitors(SCs).This GPE based SC not only exhibits prominent rate performance(105%capacitance retention at the current density of 40A g^(-1))and cyclic stability(85%at 1 A g^(-1)under 3.5 V after 20,000 cycles),but also displays remarkable energy density(42.88 Wh kg^(-1))with high power density(19.3 k W kg^(-1)).Moreover,the superior rate and cycling performances of the as-prepared GPE based flexible SCs under flat and bending state confirm the feasibility of its application in flexible energy storage devices.
基金supported by the National Key R&D Program of China(Grant No.2020YFA0710500)the basic scientific research business expenses Program of Xi’an Jiaotong University(Grant No.xzy022022053)the Independent Research Project of the State Key Laboratory of Electrical Insulation and Power Equipment(Grant No.EIPE23303)for financial support。
文摘Lithium(Li)metal batteries(LMBs)are widely regarded as the ultimate choice for the next generation of high-energy–density batteries.However,the uncontrollable growth of Li dendrites formed by inhomogeneous deposition seriously hinders its commercialization.Although many studies have achieved significant results in inhibiting the formation of Li dendrites,it is still impossible to eradicate them completely.Therefore,regulating the deposition behavior,such as the growth direction of unevenly deposited Li,is preferable to unilaterally suppressing them in some cases.Here we report a structured anode that can confine the deposited Li within holes and tune it to become vertical-up/horizontal-centripetal mixed growth mode by optimizing the electric field/Li^(+)concentration gradient.The Li^(+) adsorbed by the poly(amic acid)(PAA)insulating layer coated on the anode surface can form the Li^(+)concentration gradient pointing to the center of the hole.Combined with the special electric field formed by the hole structure,it is favorable for the Li^(+)to move into the vertically arrayed holes and simultaneously deposit on the bottom and walls.Furthermore,both in-situ and ex-situ observations confirm that the growth mode is changed and the Li deposition morphology is denser,which can greatly delay capacity fading and prolong cycle life in both liquid and quasi-solid-state LMBs.All the results show that the novel anode provides a new perspective for deep research into solid-state LMBs.
基金supported in part by Open Foundation of State key Laboratory of Networking and Switching Technology(Beijing University of Posts and Telecommunications)(SKLNST-2022-1-15)in part by the Future Network Scientific Research Fund Project under Grant FNSRFP-2021-YB-7+5 种基金in part by the Provincial Water Science and Technology Program of Jiangsu under Grant 2020028in part by Social and People's Livelihood Technology in Nantong City under Grant MS22021042in part by the Fundamental Research Funds for the Central Universities under Grant B200205007in part by the Provincial Key Research and Development Program of Jiangsu under Grant BE2019017in part by the Open Research Fund Key Laboratory of Wireless Sensor Network and Communication,Chinese Academy of Sciences,under Grant 20190914in part by the Project of National Natural Science Foundation of China 62271190。
文摘In this paper,a trusted multi-task distribution mechanism for Internet of Vehicles based on smart contract is proposed to improve the security and efficiency for the task distribution in Internet of Vehicles.Firstly,a three-tier trusted multi-task distribution framework is presented based on smart contract.The smart contract will be triggered by the task request.As the important part of the smart contract,the task distribution algorithm is stored on the blockchain and run automatically.In the process of the task distribution,the cost of the task distribution and the system stability play a critical role.Therefore,the task distribution problem is formulated to minimize the cost of the task distribution whilst maintaining the stability of the system based on Lyapunov theorem.Unfortunately,this problem is a mixed integer nonlinear programming problem with NP-hard characteristics.To tackle this,the optimization problem is decomposed into two sub problems of computing resource allocation and task distribution decision,and an effective task distribution algorithm is proposed.Simulation results show that the proposed algorithm can effectively improves system performance.
基金Supported by National Natural Science Foundation of China(Grant No.51575102)Jiangsu Postgraduate Research Innovation Program(Grant No.KYCX18_0075).
文摘Most gear fault diagnosis(GFD)approaches su er from ine ciency when facing with multiple varying working conditions at the same time.In this paper,a non-negative matrix factorization(NMF)-theoretic co-clustering strategy is proposed specially to classify more than one task at the same time using the high dimension matrix,aiming to o er a fast multi-tasking solution.The short-time Fourier transform(STFT)is first used to obtain the time-frequency features from the gear vibration signal.Then,the optimal clustering numbers are estimated using the Bayesian information criterion(BIC)theory,which possesses the simultaneous assessment capability,compared with traditional validity indexes.Subsequently,the classical/modified NMF-based co-clustering methods are carried out to obtain the classification results in both row and column tasks.Finally,the parameters involved in BIC and NMF algorithms are determined using the gradient ascent(GA)strategy in order to achieve reliable diagnostic results.The Spectra Quest’s Drivetrain Dynamics Simulator gear data sets were analyzed to verify the e ectiveness of the proposed approach.
基金supported by the National Natural Science Foundation of China(No.11002010)
文摘A new continuum damage mechanics model for fretting fatigue life prediction is established. In this model, the damage evolution rate is described by two kinds of quantities. One is associated with the cyclic stress characteristics obtained by the finite element （FE） analysis, and the other is associated with the material fatigue property identified from the fatigue test data of standard specimens. The wear is modeled by the energy wear law to simulate the contact geometry evolution. A two-dimensional （2D） plane strain FE implementation of the damage mechanics model and the energy wear model is presented in the platform of ABAQUS to simulate the evolutions of the fatigue damage and the wear scar. The effect of the specimen thickness is also investigated. The predicted results of the crack initiation site and the fretting fatigue life agree well with available experimental data. Comparisons are made with the critical plane Smith- Watson-Topper （SWT） method.
基金supported by Science and Technology Department of Sichuan Province(2017JZ0021,2017SZ0039)Education Department of Sichuan Province(17ZA0298)Innovative Training Program for College Students of Sichuan Province(No.201810626118)。
文摘A superamphiphobic(SAP)surface was fabricated by electrodepositing Cu-Ni micro-nano particles on aluminum substrate and modifying via 1 H,1 H,2 H,2 Hperfluorodecyltrimethoxysilane.Scanning electron microscopy,X-ray diffraction,energydispersive X-ray spectroscopy,and Fourier-transform infrared spectroscopy were employed to investigate the morphology and chemical composition.The results showed that the SAP surface had three-dimensional micro-nano structures and exhibited a maximum water contact angle of 160.0°,oil contact angle of 151.6°,a minimum water slide angle of 0°and oil slide angle of 9°.The mechanical strength and chemical stability of the SAP surface were tested further.The experimental results showed that the SAP surface presented excellent resistance to wear,prominent acid-resistance and alkali-resistance,self-cleaning and anti-fouling properties.
基金Supported by National Natural Science Foundation of China(Grant No.51835009).
文摘Gear fault diagnosis technologies have received rapid development and been effectively implemented in many engineering applications.However,the various working conditions would degrade the diagnostic performance and make gear fault diagnosis(GFD)more and more challenging.In this paper,a novel model parameter transfer(NMPT)is proposed to boost the performance of GFD under varying working conditions.Based on the previous transfer strategy that controls empirical risk of source domain,this method further integrates the superiorities of multi-task learning with the idea of transfer learning(TL)to acquire transferable knowledge by minimizing the discrepancies of separating hyperplanes between one specific working condition(target domain)and another(source domain),and then transferring both commonality and specialty parameters over tasks to make use of source domain samples to assist target GFD task when sufficient labeled samples from target domain are unavailable.For NMPT implementation,insufficient target domain features and abundant source domain features with supervised information are fed into NMPT model to train a robust classifier for target GFD task.Related experiments prove that NMPT is expected to be a valuable technology to boost practical GFD performance under various working conditions.The proposed methods provides a transfer learning-based framework to handle the problem of insufficient training samples in target task caused by variable operation conditions.
文摘Vaccine is a principal and highly cost-effective medical method on controlling infectious diseases and improving population health.Various vaccines are eagerly needed in the low-income countries along the Belt&Road.With the good quality to reach WHO prequalification standard,and the abundant capacity to fulfill the demand from market abroad,upon the platform of China-proposed"the Belt&Road Initiative",the vaccines manufactured in China are exporting to countries worldwide.The independent innovative vaccines'R&D system,which fruited a series of innovative infectious diseases vaccines(EV71 vaccine,sIPV,HEV,Ebola vaccine,etc.)to be launched in Chinese market,indicates that China has developed rapidly from"a great vaccine-production country"to"a powerful vaccine-innovation country".The implementation of National Innovation-driven Development Strategy would further push forward the developm ent and internationalization process of Chinese innovative vaccines.Therefore,the China-invented vaccines will make an important role in the prevention and control of infectious disease in various countries and become one of the most powerful weapons in fighting the global epidemic event in the future.
基金financial support by National Natural Science Foundation of China(Nos.22176019,51978110)the Science and Technology Research Program of Chongqing Municipal Education Commission(Nos.KJQN201800829,KJQN201900837,KJZD-K202000802,KJQN201901527)+1 种基金Chongqing Research Student Science and Technology Innovation Project(No.CYS22724)Innovation and Entrepreneurship Training Plan for College Students(No.202111799007).
文摘This work reported a facile approach to surface oxygen vacancy(O_(v))-enriched urchin-like TiO_(2) microparticles(U-TiO_(2)),which were highly effective and durable in catalyzing selective nitrate reduction to ammonia(NOgRR),Specifically,the U-TiO_(2)delivered a mass activity of 1.15 min^(-1)mg^(-1)calyst.a low yield of toxic NO_(2)^(-)-N intermediate(≤0.4mg/L)and an exceptional high NH_(3)^(-)-N selectivity of 98.1%in treating 22.5 mg/L of NO_(3)^(-)-N under a potential of-0.60V vs.RHE,outperforming most of the reported oxidebased catalysts.When comparing the performance of U-TiO_(2)with that of the solid amorphous TiO_(2) counterpart(A-TiO_(2))that had close particle size but more O_(v) on surfaces,we identified that the O_(v) was the reactive sites,but rather than its content,the NO_(3)RR kinetics were primarily limited by the electron and mass transfer at U-TiO_(2)/water interfaces.Accordingly,the superior performance of U-TiO_(2)to A-TiO_(2)could be ascribed to the hierarchical urchin-like structure in U-TiO_(2).The in-situ DEMS test revealed that the NO_(3)RR on U-TiO_(2)followed a pathway of ^(*)NO_(3)^(-)→^(*)NO_(2)^(-)→^(*)NO→^(*)N→^(*)NH^(-)→^(*)NH_(2)→^(*)NH_(3).We also demonstrated that the U-TiO_(2) could keep its robust performance under a wide NO_(3)^(-)-N concentration range and in the presence of some co-existing ions(such as Ca^(2+),Cl^(-),Mg^(2+)).However,the presence of humic acid and CO_(3)^(2-) in water slowed down the NO_(3)RR on U-TiO_(2).This work provides a more fundamental insight into the O_(v)-driven NO_(3)RR process on TiO_(2),which should benefit for the development of eficient TiO_(2)-based catalvsts.
基金supported by the National Key R&D Program of China (Grant No.2020YFA0710500)The authors acknowledge the basic scientific research business expenses Program of Xi’an Jiaotong University (Grant No.xzy022022053)the Independent Research Project of the State Key Laboratory of Electrical Insulation and Power Equipment (Grant No.EIPE23303)for financial support.
文摘Safety issues induced by infinite anode volume change and uncontrolled lithium(Li)dendrite growth have become the biggest obstacle to the practical application of Li metal batteries.In addition,the tra-ditional rolling method makes it difficult to manufacture thin Li foil with high mechanical strength and low Li content.Herein,a three-dimensional(3D)lithophilic carbon paper/copper(Cu)current collector hybrid anode with ultra-low Li metal content is prepared by a hot-pressing method.The highly re-versible and stable lithiophilic layer LiC_(x) formed in situ by heating/pressing treatment provides abun-dant nucleation sites and reduces the Li nucleation overpotential,thereby effectively suppressing Li den-drite growth.Moreover,the volume change and pulverization problems of Li metal anode during depo-sition/stripping also can be accommodated by the 3D skeleton.The optimization effect has been directly confirmed by in-situ optical and ex-situ scanning electron microscope observation.Therefore,highly sta-ble performance(158.4 mA h g^(-1) at 2 C after 200 cycles with a capacity retention of 95.24%)in Li@LCP-Cu||NCM811 coin cell can be achieved.Furthermore,the solid-state battery assembled with the hybrid anode,poly(vinylidene fluoride)(PVDF)-based polymer electrolyte and polyethylene oxide(PEO)interface functional layer also exhibits the best electrochemical and safety performance,which also proves that the Li@LCP-Cu anode has great potential for application in solid-state batteries.
基金the National Natural Science Foundation of China(Nos.42104014,42077003,41904018)Natural Science Foundation of the Higher Education Institutions of Jiangsu Province,China(21KJB420005)State Key Laboratory of Geodesy and Earth’s Dynamics(SKLGED2022-3-6)and Highlevel innovation and entrepreneurship talent plan of Jiangsu Province.
文摘A new Precise Point Positioning(PPP)service,called the PPP-B2b service,has been implemented in the BeiDou-3 Navigation Satellite System(BDS-3),which brings new opportunities for time transfer.However,the solution using the traditional PPP method with the PPP-B2b correction still absorbs some unknown errors and needs reconverging when there exist abnormal data.We developed a new receiver clock model to improve PPP time transfer using the PPP-B2b correction.The traditional PPP time transfers using PPP-B2b with BDS-3,Global Positioning System(GPS),and BDS-3/GPS(Scheme1)are compared with the corresponding time transfer with the proposed clock model(Scheme2).The results show that GPS-only PPP is not recommended because of low accuracy of 2 ns.BDS-3 or BDS-3/GPS PPP time transfers in Scheme1 can realize about 0.2 ns accuracy.When the new clock model is applied,the accuracy can be improved by up to 45%and 39.8%for BDS-3 and BDS-3/GPS PPP,respectively.The proposed clock model can signifcantly improve the short-term frequency stability by 57.4%,but less for the long-term stability.
基金supported by the Beijing Academy of Agriculture and Forestry Sciences(KJCX201907-2 to J.W.,KJCX201917 to C.Z.,and KJCX20200204 and KJCX20220105 to X.Y.)the Beijing Postdoctoral Research Foundation(2021-ZZ-133 to B.L.)the National Natural Science Foundation of China(31621001 to X.Y.).
文摘As a globally popular leafy vegetable and a representative plant of the Asteraceae family,lettuce has great economic and academic significance.In the last decade,high-throughput sequencing,phenotyping,and other multi-omics data in lettuce have accumulated on a large scale,thus increasing the demand for an integrative lettuce database.Here,we report the establishment of a comprehensive lettuce database,LettuceGDB(https://www.lettucegdb.com/).As an omics data hub,the current LettuceGDB includes two reference genomes with detailed annotations;re-sequencing data from over 1000 lettuce varieties;a collection of more than 1300 worldwide germplasms and millions of accompanying phenotypic records obtained with manual and cutting-edge phenomics technologies;re-analyses of 256 RNA sequencing datasets;a complete miRNAome;extensive metabolite information for representative varieties and wild relatives;epigenetic data on the genome-wide chromatin accessibility landscape;and various lettuce research papers published in the last decade.Five hierarchically accessible functions(Genome,Genotype,Germplasm,Phenotype,and O-Omics)have been developed with a user-friendly interface to enable convenient data access.Eight built-in tools(Assembly Converter,Search Gene,BLAST,JBrowse,Primer Design,Gene Annotation,Tissue Expression,Literature,and Data)are available for data downloading and browsing,functional gene exploration,and experimental practice.A community forum is also available for information sharing,and a summary of current research progress on different aspects of lettuce is included.We believe that LettuceGDB can be a comprehensive functional database amenable to data mining and database-driven exploration,useful for both scientific research and lettuce breeding.
基金supported by National Natural Science Foundation of China (Nos. 61503378, 61473293, 51405485 and 61403378)the Project of Development in Tianjin for Scientific Research Institutes, and Tianjin Government (No. 16PTYJGX00050)
文摘Object contour plays an important role in fields such as semantic segmentation and image classification. However, the extraction of contour is a difficult task, especially when the contour is incomplete or unclosed. In this paper, the existing contour detection approaches are reviewed and roughly divided into three categories： pixel-based, edge-based, and region-based. In addition, since the traditional contour detection approaches have achieved a high degree of sophistication, the deep convolutional neural networks （DCNNs） have good performance in image recognition, therefore, the DCNNs based contour detection approaches are also covered in this paper. Moreover, the future development of contour detection is analyzed and predicted.
基金financially supported by the National Natural Science Foundation of China(No.51772241)the Key Research Program of Shaanxi Province(No.2017ZDXM-GY-035)+2 种基金the Young Talent Support Plan of Xi’an Jiaotong University(No.DQ1J006)the Project from State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University(No.EIPE17306)the Fundamental Research Funds for the Central Universities(Nos.zrzd2017004,xjj2017076)for financial support
文摘Lithium （Li） metal has been considered as the most attractive anode materials for Li-ion batteries （LIBs） due to its high theoretic specific capacity. The formation of unstable solid electrolyte interphase （SEI） and dendritic Li on the metal anode, however, hindered its practical application. Herein, to address the issues, a Li-free electrode with ultrathin Al2O3 coated on reduced graphene oxide （rGO） membrane that covers a Cu foil current collector was developed. The composite electrode exhibits excellent interfacial protection of lithium metal deposited between Cu foil and rGO electrochemically. Firstly, it affords good Li^＋ permeability from the electrolyte. Secondly, the ultrathin Al2O3 has sufficient mechanical strength to inhibit the penetration of Li dendrite. Li metal was observed uniformly deposited between rGO membrane and Cu collector, and stable cycle performance of Li plating/stripping with Coulombic efficiency of ~ 91.75% at the lOOth cycle is achieved in organic carbonate electrolyte without any additives.
基金C. B. G. acknowledges the support from the National Natural Science Foundation of China （Nos. 21671156 and 21301138）, the Tang Scholar Program from the Cyrus Tang Foundation, and the start-up fund from Xi＇an Jiaotong University. X. G. H acknowledges the programs supported by State Key Laboratory of Electrical Insulation and Power Equipment （No. EIPE17306） and Young Talent Support Plan of Xi＇an Jiaotong University. Y. D. Y. acknowledges the support from U.S. Department of Energy （No. DE-SC0002247）.
文摘Sub-100 nm hollow carbon nanospheres with thin shells are highly desirable anode materials for energy storage applications. However, their synthesis remains a great challenge with conventional strategies. In this work, we demonstrate that hollow carbon nanospheres of unprecedentedly small sizes （down to - 32.5 nm and with thickness of - 3.9 nm） can be produced on a large scale by a templating process in a unique reverse micelle system. Reverse micelles enable a spatially confined Stober process that produces uniform silica nanospheres with significantly reduced sizes compared with those from a conventional Stober process, and a subsequent well-controlled sol-gel coating process with a resorcinol-formaldehyde resin on these silica nanospheres as a precursor of the hollow carbon nanospheres. Owing to the short diffusion length resulting from their hollow structure, as well as their small size and microporosity, these hollow carbon nanospheres show excellent capacity and cycling stability when used as anode materials for lithium/sodium-ion batteries.
基金supported by the National Natural Science Foundation of China(No.11002010)
文摘An approach based on continuum damage mechanics to fatigue life prediction for structures is proposed. A new fatigue damage evolution equation is developed, in which the pa- rameters are obtained in a simple way with reference to the experimental results of fatigue tests on standard specimens. With the utilization of APDL language on the ANSYS platform, a finite element implementation is presented to perform coupling operation on damage evolution of mate- rial and stress redistribution. The fatigue lives of some notched specimens and a Pitch-change-link are predicted by using the above approach. The calculated results are validated with experimental data.
基金The authors gratefully acknowledge the financial support provided by Jiangsu Policy Guidance Program(International Science and Technology Collaboration)(BZ2021030)Wuxi Innovation and Entrepreneurship Program for Science and Technology(M20211003)+1 种基金the Pre-research Fund of Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment(XTCXSZ2020-2)Jiangsu Special Funding of Science and Technology Innovation for Carbon Emission Peaking and Carbon Neutrality(BE2021409).
文摘A large number of pharmaceuticals and personal care products(PPCPs)persist in wastewater,and the consumption of PPCPs for COVID-19 control and prevention has sharply increased during the pandemic.This study investigated the occurrence,removal efficiency,and risk assessment of six typical PPCPs commonly used in China in two wastewater treatment plants(WWTPs).Ribavirin(RBV)is an effective pharmaceutical for severely ill patients with COVID-19,and the possible biodegradation pathway of RBV by activated sludge was discovered.The experimental results showed that PPCPs were detected in two WWTPs with a detection rate of 100%and concentrations ranging between 612 and 2323 ng L^(-1).The detection frequency and concentrations of RBV were substantially higher,with a maximum concentration of 314 ng L^(-1).Relatively high pollution loads were found for the following PPCPs from influent:ibuprofen>ranitidine hydrochloride>RBV>ampicillin sodium>clozapine>sulfamethoxazole.The removal efficiency of PPCPs was closely related to adsorption and biodegradation in activated sludge,and the moving bed biofilm reactor(MBBR)had a higher removal capacity than the anoxic-anaerobic-anoxicoxic(AAAO)process.The removal efficiencies of sulfamethoxazole,ampicillin sodium,ibuprofen,and clozapine ranged from 92.21%to 97.86%in MBBR process and were relatively low,from 61.82%to 97.62%in AAAO process,and the removal of RBV and ranitidine hydrochloride were lower than 42.96%in both MBBR and AAAO processes.The discrepancy in removal efficiency is caused by temperature,hydrophilicity,and hydrophobicity of the compound,and acidity and alkalinity.The transformation products of RBV in activated sludge were detected and identified,and the biodegradation process of RBV could be speculated as follows:first breaks into TCONH_(2) and an oxygen-containing five-membered heterocyclic ring under the nucleosidase reaction,and then TCONH_(2) is finally formed into TCOOH through amide hydrolysis.Aquatic ecological risks based on risk quotient(RQ)assessment showed that PPCPs had high and medium risks in the influent,and the RQ values were all reduced after MBBR and AAAO treatment.Ranitidine hydrochloride and clozapine still showed high and medium risks in the effluent,respectively,and thus presented potential risks to the aquatic ecosystem.
