Identifying a device and detecting a change in its position is critical for secure devices management in the Internet of Things(IoT).In this paper,a device management system is proposed to track the devices by using a...Identifying a device and detecting a change in its position is critical for secure devices management in the Internet of Things(IoT).In this paper,a device management system is proposed to track the devices by using audio-based location distinction techniques.In the proposed scheme,traditional cryptographic techniques,such as symmetric encryption algorithm,RSA-based signcryption scheme,and audio-based secure transmission,are utilized to provide authentication,non-repudiation,and confidentiality in the information interaction of the management system.Moreover,an audio-based location distinction method is designed to detect the position change of the devices.Specifically,the audio frequency response(AFR)of several frequency points is utilized as a device signature.The device signature has the features as follows.(1)Hardware Signature:different pairs of speaker and microphone have different signatures;(2)Distance Signature:in the same direction,the signatures are different at different distances;and(3)Direction Signature:at the same distance,the signatures are different in different directions.Based on the features above,amovement detection algorithmfor device identification and location distinction is designed.Moreover,a secure communication protocol is also proposed by using traditional cryptographic techniques to provide integrity,authentication,and non-repudiation in the process of information interaction between devices,Access Points(APs),and Severs.Extensive experiments are conducted to evaluate the performance of the proposed method.The experimental results show that the proposedmethod has a good performance in accuracy and energy consumption.展开更多
The lattice doping has been widely used to improve the electrochemical performances of Li-rich cathode materials but the roles of the introduced foreign atoms are still not very clear.Herein,a series of Li2Ru1-xTixO3 ...The lattice doping has been widely used to improve the electrochemical performances of Li-rich cathode materials but the roles of the introduced foreign atoms are still not very clear.Herein,a series of Li2Ru1-xTixO3 solid solutions have been synthesized and the roles of Ti doping on the structural and electrochemical properties of Li2RuO3 have been comprehensively investigated.The Rietveld refinement exhibits that the interlayer spacing gradually shortens with increasing Ti content.This shrinkage is favorable to the layered structure stability but increases the lithium diffusion barrier.Galvanostatic measurements show that Li2Ru0.8Ti0.2O3 possesses the best cyclability with 196.9 and 196.1 m Ah g-1for charge and discharge capacity retaining after 90 cycles,respectively.Cyclic voltammetry scanning indicates that Ti dopant promotes the formation of more peroxo-or superoxo-like species but reduces the initial coulumbic efficiency.Results of electrochemical impedance spectroscopy display that Ti doping reduces the charge transfer impedance,which facilitates the lithium-ion diffusion across the electrolyteelectrode interface and improves the electronic conductivity.Li2Ru0.8Ti0.2O3exhibits the best electrochemical performance owing to the balance among all the factors discussed above.This study also offers some new insights into optimizing the electrochemical performances of Li-rich cathode materials through the lattice doping.展开更多
1.Introduction The rock mass engineering system(RMES)basically consists of rock mass engineering(RME),water system and surrounding ecological environments.etc.The RMES is characterized by nonlinearity,occurrence of ch...1.Introduction The rock mass engineering system(RMES)basically consists of rock mass engineering(RME),water system and surrounding ecological environments.etc.The RMES is characterized by nonlinearity,occurrence of chaos and self-organization(Tazaka,1998;Tsuda,1998;Kishida,2000).From construction to abandonment of RME,the RMES will experience four stages,i.e.initial phase,development phase,declining phase and failure phase.In展开更多
It is a difficult task to root the cause of the failure of a gas face seal because different causes may result in similar observations.In the work being presented,the discrimination of multiple types of abnormities in...It is a difficult task to root the cause of the failure of a gas face seal because different causes may result in similar observations.In the work being presented,the discrimination of multiple types of abnormities in a spiral groove gas face seal is studied.A dynamic model is employed to analyze groups of cases in order to uncover the dynamic behaviors when the face contact is induced by different mixtures of abnormities,whose discriminative features when motion and contact are monitored are studied and uncovered.A circumferential-pattern-related oscillation phenomenon is discovered,which is extracted from contact information and implies the relative magnitude of the moment on stator and the rotor tilt.The experimental observation shows consistent results.It means that the grooves(or other circumferential patterns)generate useful informative features for monitoring.These results provide guidance for designing a monitored gas face seal system.展开更多
Oxygen anion redox chemistry in layered oxide cathodes for sodium-ion batteries has attracted great interest.However,the release of lattice oxygen caused by the irreversible anionic redox and Jahn–Teller effect accel...Oxygen anion redox chemistry in layered oxide cathodes for sodium-ion batteries has attracted great interest.However,the release of lattice oxygen caused by the irreversible anionic redox and Jahn–Teller effect accelerates the structural distortion and electrochemical degradation.Herein,we rationally construct a stable crystal lattice to enhance the reactivity and reversibility of oxygen redox and inhibit the Jahn–Teller effect by Sn doping.The stronger binding energy of Sn–O enhances the structural stability of the cathode,which is favorable to suppress the oxygen release and Jahn–Teller effect.Thus,the reversibility of oxygen redox and the stability of the layered structure are enhanced.The expansion of the interlayer spacing decreases the energy barriers for Na+ion intercalation,improving the rate performance of the electrode.Benefitting from the rational design,the electrode delivers an enhanced rate performance and cycling stability.This work offers some insights into tuning the oxygen anion redox chemistry as well as suppressing the Jahn–Teller effect by lattice modulation.展开更多
The friction behavior of resin-impregnated and non-impregnated graphite sliding against a cemented carbide in dry, oil, and water environments using a ring–ring configuration was investigated. Friction coefficients w...The friction behavior of resin-impregnated and non-impregnated graphite sliding against a cemented carbide in dry, oil, and water environments using a ring–ring configuration was investigated. Friction coefficients were recorded at various speeds. The results showed that the impregnated graphite exhibited much better friction properties under water or oil lubrication than non-impregnated graphite, and the impregnated graphite could remain in the stable friction regime under high pressure × velocity(pv).Based on scanning electron microscopy and Raman spectroscopy analyses, the different characteristics between impregnated and non-impregnated graphite were able to be attributed to the structure of the graphite and wettability of the lubricants.展开更多
Wear of hard materials in contact with softer materials is a neglected area of research. However, we observed considerable wear phenomenon at a hard WC-Ni surface sliding over soft graphite under water lubrication. Th...Wear of hard materials in contact with softer materials is a neglected area of research. However, we observed considerable wear phenomenon at a hard WC-Ni surface sliding over soft graphite under water lubrication. The influences of applied load and the application history on the wear of surface were addressed in our experimental design. Wear of both graphite and WC-Ni surfaces increased with a greater applied load and repeated sliding. The topographies of the worn surfaces showed clear micro-scratches on the hard WC-Ni surface. Scanning electron microscopy and X-ray photoelectron spectroscopy analyses revealed that the abrasive wear of the WC-Ni surface could be attributed to hard WC particles embedded in the graphite surface. These hard particles were formed by shearing of sharp WC-Ni asperities under certain conditions and intrinsic defects of the WC-Ni surface could accelerate this wear process.展开更多
Two types of commercial WC-Ni samples were irradiated with the High-intensity pulsed ion beam(HIPIB).Both the surface characteristics and tribo-characteristics of the non-irradiated and irradiated WC-Ni samples,slidin...Two types of commercial WC-Ni samples were irradiated with the High-intensity pulsed ion beam(HIPIB).Both the surface characteristics and tribo-characteristics of the non-irradiated and irradiated WC-Ni samples,sliding against graphite under water lubrication,were compared.Quite low steady friction coefficients(approximately of 0.02) of the irradiated WC-Ni were observed.The surface topographies and components were investigated.The quite low friction of the irradiated WC-Ni samples was ascribed to the higher fluid retention capability of the latter and the tribofilm formed during sliding.展开更多
钾离子电池在大规模储能方面具有广阔的前景.然而,缺乏合适的正极材料限制了其实际应用.此外,为钾离子电池合理设计先进的正极材料仍然面临挑战.本工作中,通过密度泛函理论计算,我们发现层状过渡金属氧化物中Fe-O键稳定性高于Co-O键.此...钾离子电池在大规模储能方面具有广阔的前景.然而,缺乏合适的正极材料限制了其实际应用.此外,为钾离子电池合理设计先进的正极材料仍然面临挑战.本工作中,通过密度泛函理论计算,我们发现层状过渡金属氧化物中Fe-O键稳定性高于Co-O键.此外,Fe基层状氧化物中的钾离子迁移具有明显低于Co基氧化物的活化能垒.基于这一理论预测,我们成功合成了一种低成本的K_(0.45)Ni_(0.1)Fe_(0.1)Mn_(0.8)O_(2)正极,该正极显示出优异的结构稳定性和储钾性能,包括较长的循环寿命和高倍率性能.此外,所设计的K_(0.45)Ni_(0.1)Fe_(0.1)Mn_(0.8)O_(2)正极具有良好的全电池性能,放电容量约为75 mA h g^(-1),100次循环后容量保持率约为80%.在层状氧化物正极中,Fe比高成本Co具有更好的结构稳定性和钾离子扩散能力,这一发现为低成本和高性能钾离子电池层状正极的设计提供了新的思路.这项工作突出了以理论为指导的实验在筛选有前景的电池材料方面的可行性.展开更多
Physical models carry quantitative and explainable expert knowledge.However,they have not been introduced into gas face seal diagnosis tasks because of the unacceptable computational cost of inferring the input fault ...Physical models carry quantitative and explainable expert knowledge.However,they have not been introduced into gas face seal diagnosis tasks because of the unacceptable computational cost of inferring the input fault parameters for the observed output or solving the inverse problem of the physical model.The presented work develops a surrogate-model-assisted method for solving the nonlinear inverse problem in limited physical model evaluations.The method prepares a small initial database on sites generated with a Latin hypercube design and then performs an iterative routine that benefits from the rapidity of the surrogate models and the reliability of the physical model.The method is validated on simulated and experimental cases.Results demonstrate that the method can effectively identify the parameters that induce the abnormal signal output with limited physical model evaluations.The presented work provides a quantitative,explainable,and feasible approach for identifying the cause of gas face seal contact.It is also applicable to mechanical devices that face similar difficulties.展开更多
基金This work is supported by Demonstration of Scientific and Technology Achievements Transform in Sichuan Province under Grant 2022ZHCG0036National Natural Science Foundation of China(62002047).
文摘Identifying a device and detecting a change in its position is critical for secure devices management in the Internet of Things(IoT).In this paper,a device management system is proposed to track the devices by using audio-based location distinction techniques.In the proposed scheme,traditional cryptographic techniques,such as symmetric encryption algorithm,RSA-based signcryption scheme,and audio-based secure transmission,are utilized to provide authentication,non-repudiation,and confidentiality in the information interaction of the management system.Moreover,an audio-based location distinction method is designed to detect the position change of the devices.Specifically,the audio frequency response(AFR)of several frequency points is utilized as a device signature.The device signature has the features as follows.(1)Hardware Signature:different pairs of speaker and microphone have different signatures;(2)Distance Signature:in the same direction,the signatures are different at different distances;and(3)Direction Signature:at the same distance,the signatures are different in different directions.Based on the features above,amovement detection algorithmfor device identification and location distinction is designed.Moreover,a secure communication protocol is also proposed by using traditional cryptographic techniques to provide integrity,authentication,and non-repudiation in the process of information interaction between devices,Access Points(APs),and Severs.Extensive experiments are conducted to evaluate the performance of the proposed method.The experimental results show that the proposedmethod has a good performance in accuracy and energy consumption.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11575192 and 21403129)the Scientific Instrument Developing Project (Grant No. ZDKYYQ20170001)+2 种基金the International Partnership Program (Grant No. 211211KYSB20170060)“Hundred Talents Project” of the Chinese Academy of SciencesNatural Science Foundation of Beijing Municipality (Grant No. 2182082)
文摘The lattice doping has been widely used to improve the electrochemical performances of Li-rich cathode materials but the roles of the introduced foreign atoms are still not very clear.Herein,a series of Li2Ru1-xTixO3 solid solutions have been synthesized and the roles of Ti doping on the structural and electrochemical properties of Li2RuO3 have been comprehensively investigated.The Rietveld refinement exhibits that the interlayer spacing gradually shortens with increasing Ti content.This shrinkage is favorable to the layered structure stability but increases the lithium diffusion barrier.Galvanostatic measurements show that Li2Ru0.8Ti0.2O3 possesses the best cyclability with 196.9 and 196.1 m Ah g-1for charge and discharge capacity retaining after 90 cycles,respectively.Cyclic voltammetry scanning indicates that Ti dopant promotes the formation of more peroxo-or superoxo-like species but reduces the initial coulumbic efficiency.Results of electrochemical impedance spectroscopy display that Ti doping reduces the charge transfer impedance,which facilitates the lithium-ion diffusion across the electrolyteelectrode interface and improves the electronic conductivity.Li2Ru0.8Ti0.2O3exhibits the best electrochemical performance owing to the balance among all the factors discussed above.This study also offers some new insights into optimizing the electrochemical performances of Li-rich cathode materials through the lattice doping.
基金funded by the National Natural Science Foundation of China(Grant Nos.51274110,51304108,U1361211)
文摘1.Introduction The rock mass engineering system(RMES)basically consists of rock mass engineering(RME),water system and surrounding ecological environments.etc.The RMES is characterized by nonlinearity,occurrence of chaos and self-organization(Tazaka,1998;Tsuda,1998;Kishida,2000).From construction to abandonment of RME,the RMES will experience four stages,i.e.initial phase,development phase,declining phase and failure phase.In
基金Supported by the National Key R&D Program of China(Grant No.2020YFB2010000)the National Natural Science Foundation of China(Grant No.U1737209).
文摘It is a difficult task to root the cause of the failure of a gas face seal because different causes may result in similar observations.In the work being presented,the discrimination of multiple types of abnormities in a spiral groove gas face seal is studied.A dynamic model is employed to analyze groups of cases in order to uncover the dynamic behaviors when the face contact is induced by different mixtures of abnormities,whose discriminative features when motion and contact are monitored are studied and uncovered.A circumferential-pattern-related oscillation phenomenon is discovered,which is extracted from contact information and implies the relative magnitude of the moment on stator and the rotor tilt.The experimental observation shows consistent results.It means that the grooves(or other circumferential patterns)generate useful informative features for monitoring.These results provide guidance for designing a monitored gas face seal system.
基金the National Natural Science Foundation of China(grant nos.11975238 and 11575192)the Chinese Academy of Sciences(grant nos.ZDKYYQ20170001,211211KYSB20170060,and 211211KYSB20180020)the Natural Science Foundation of Beijing Municipality(grant no.2182082).
文摘Oxygen anion redox chemistry in layered oxide cathodes for sodium-ion batteries has attracted great interest.However,the release of lattice oxygen caused by the irreversible anionic redox and Jahn–Teller effect accelerates the structural distortion and electrochemical degradation.Herein,we rationally construct a stable crystal lattice to enhance the reactivity and reversibility of oxygen redox and inhibit the Jahn–Teller effect by Sn doping.The stronger binding energy of Sn–O enhances the structural stability of the cathode,which is favorable to suppress the oxygen release and Jahn–Teller effect.Thus,the reversibility of oxygen redox and the stability of the layered structure are enhanced.The expansion of the interlayer spacing decreases the energy barriers for Na+ion intercalation,improving the rate performance of the electrode.Benefitting from the rational design,the electrode delivers an enhanced rate performance and cycling stability.This work offers some insights into tuning the oxygen anion redox chemistry as well as suppressing the Jahn–Teller effect by lattice modulation.
基金supported by the National Basic Research Program of China (973) (Grant No. 2015CB057303)the National Natural Science Foundation of China (Grant No. 51275268)
文摘The friction behavior of resin-impregnated and non-impregnated graphite sliding against a cemented carbide in dry, oil, and water environments using a ring–ring configuration was investigated. Friction coefficients were recorded at various speeds. The results showed that the impregnated graphite exhibited much better friction properties under water or oil lubrication than non-impregnated graphite, and the impregnated graphite could remain in the stable friction regime under high pressure × velocity(pv).Based on scanning electron microscopy and Raman spectroscopy analyses, the different characteristics between impregnated and non-impregnated graphite were able to be attributed to the structure of the graphite and wettability of the lubricants.
基金supported by the National Basic Research Program of China (“973 Program”) (Grant No. 2015CB057303)the National Natural Science Foundation of China (Grant No. 51275268)
文摘Wear of hard materials in contact with softer materials is a neglected area of research. However, we observed considerable wear phenomenon at a hard WC-Ni surface sliding over soft graphite under water lubrication. The influences of applied load and the application history on the wear of surface were addressed in our experimental design. Wear of both graphite and WC-Ni surfaces increased with a greater applied load and repeated sliding. The topographies of the worn surfaces showed clear micro-scratches on the hard WC-Ni surface. Scanning electron microscopy and X-ray photoelectron spectroscopy analyses revealed that the abrasive wear of the WC-Ni surface could be attributed to hard WC particles embedded in the graphite surface. These hard particles were formed by shearing of sharp WC-Ni asperities under certain conditions and intrinsic defects of the WC-Ni surface could accelerate this wear process.
基金financially supported by both the National Basic Research Program of China(973)(Grant No.2015CB057303)the National Natural Science Foundation of China(Grant No.51275268)
文摘Two types of commercial WC-Ni samples were irradiated with the High-intensity pulsed ion beam(HIPIB).Both the surface characteristics and tribo-characteristics of the non-irradiated and irradiated WC-Ni samples,sliding against graphite under water lubrication,were compared.Quite low steady friction coefficients(approximately of 0.02) of the irradiated WC-Ni were observed.The surface topographies and components were investigated.The quite low friction of the irradiated WC-Ni samples was ascribed to the higher fluid retention capability of the latter and the tribofilm formed during sliding.
基金supported by the Fundamental Research Funds for the Central Universities and the Scientific Instrument Developing Project of the Chinese Academy of Sciences(ZDKYYQ20170001)。
文摘钾离子电池在大规模储能方面具有广阔的前景.然而,缺乏合适的正极材料限制了其实际应用.此外,为钾离子电池合理设计先进的正极材料仍然面临挑战.本工作中,通过密度泛函理论计算,我们发现层状过渡金属氧化物中Fe-O键稳定性高于Co-O键.此外,Fe基层状氧化物中的钾离子迁移具有明显低于Co基氧化物的活化能垒.基于这一理论预测,我们成功合成了一种低成本的K_(0.45)Ni_(0.1)Fe_(0.1)Mn_(0.8)O_(2)正极,该正极显示出优异的结构稳定性和储钾性能,包括较长的循环寿命和高倍率性能.此外,所设计的K_(0.45)Ni_(0.1)Fe_(0.1)Mn_(0.8)O_(2)正极具有良好的全电池性能,放电容量约为75 mA h g^(-1),100次循环后容量保持率约为80%.在层状氧化物正极中,Fe比高成本Co具有更好的结构稳定性和钾离子扩散能力,这一发现为低成本和高性能钾离子电池层状正极的设计提供了新的思路.这项工作突出了以理论为指导的实验在筛选有前景的电池材料方面的可行性.
基金This work was supported by the National Key R&D Program of China(Grant No.2020YFB2010000)the National Natural Science Foundation of China(Grant No.U1737209).None of the funding bodies influenced the study at any stage.
文摘Physical models carry quantitative and explainable expert knowledge.However,they have not been introduced into gas face seal diagnosis tasks because of the unacceptable computational cost of inferring the input fault parameters for the observed output or solving the inverse problem of the physical model.The presented work develops a surrogate-model-assisted method for solving the nonlinear inverse problem in limited physical model evaluations.The method prepares a small initial database on sites generated with a Latin hypercube design and then performs an iterative routine that benefits from the rapidity of the surrogate models and the reliability of the physical model.The method is validated on simulated and experimental cases.Results demonstrate that the method can effectively identify the parameters that induce the abnormal signal output with limited physical model evaluations.The presented work provides a quantitative,explainable,and feasible approach for identifying the cause of gas face seal contact.It is also applicable to mechanical devices that face similar difficulties.
