The undesirable dendrite growth induced by non-planar zinc(Zn)deposition and low Coulombic efficiency resulting from severe side reactions have been long-standing challenges for metallic Zn anodes and substantially im...The undesirable dendrite growth induced by non-planar zinc(Zn)deposition and low Coulombic efficiency resulting from severe side reactions have been long-standing challenges for metallic Zn anodes and substantially impede the practical application of rechargeable aqueous Zn metal batteries(ZMBs).Herein,we present a strategy for achieving a high-rate and long-cycle-life Zn metal anode by patterning Zn foil surfaces and endowing a Zn-Indium(Zn-In)interface in the microchannels.The accumulation of electrons in the microchannel and the zincophilicity of the Zn-In interface promote preferential heteroepitaxial Zn deposition in the microchannel region and enhance the tolerance of the electrode at high current densities.Meanwhile,electron aggregation accelerates the dissolution of non-(002)plane Zn atoms on the array surface,thereby directing the subsequent homoepitaxial Zn deposition on the array surface.Consequently,the planar dendrite-free Zn deposition and long-term cycling stability are achieved(5,050 h at 10.0 mA cm^(−2) and 27,000 cycles at 20.0 mA cm^(−2)).Furthermore,a Zn/I_(2) full cell assembled by pairing with such an anode can maintain good stability for 3,500 cycles at 5.0 C,demonstrating the application potential of the as-prepared ZnIn anode for high-performance aqueous ZMBs.展开更多
Correction to:Nano-Micro Letters(2024)16:112 https://doi.org/10.1007/s40820-024-01327-2 In the supplementary information the following corrections have been carried out:1.Institute of Energy and Climate Research,Mater...Correction to:Nano-Micro Letters(2024)16:112 https://doi.org/10.1007/s40820-024-01327-2 In the supplementary information the following corrections have been carried out:1.Institute of Energy and Climate Research,Materials Synthesis and Processing,Forschungszentrum Jülich GmbH,52425 Jülich,Germany.Corrected:Institute of Energy and Climate Research:Materials Synthesis and Processing(IEK-1),Forschungszentrum Jülich GmbH,52425 Jülich,Germany.展开更多
In this paper, the existence and uniqueness of almost periodic solutions for some infinite delay integral equations are discussed. By using Krasnoselskii fixed point theorem,some new results are obtained.
Decoupling the complicated vibrational-vibrational （V-V） coupling of a multimode vibrational relaxation remains a challenge for analyzing the sound relaxational absorption in multi-component gas mixtures. In our pre...Decoupling the complicated vibrational-vibrational （V-V） coupling of a multimode vibrational relaxation remains a challenge for analyzing the sound relaxational absorption in multi-component gas mixtures. In our previous work [Acta Phys. Sin. 61 174301 （2012）], an analytical model to predict the sound absorption from vibrational relaxation in a gas medium is proposed. In this paper, we develop the model to decouple the V-V coupled energy to each vibrationaltranslational deexcitation path, and analyze how the multimode relaxations form the peaks of sound absorption spectra in gas mixtures. We prove that a multimode relaxation is the sum of its decoupled single-relaxation processes, and only the decoupled process with a significant isochoric-molar-heat can be observed as an absorption peak. The decoupling model clarifies the essential processes behind the peaks in spectra arising from the multimode relaxations in multi-component gas mixtures. The simulation validates the proposed decoupling model.展开更多
Data sharing in Internet of Vehicles(IoV)makes it possible to provide personalized services for users by service providers in Intelligent Transportation Systems(ITS).As IoV is a multi-user mobile scenario,the reliabil...Data sharing in Internet of Vehicles(IoV)makes it possible to provide personalized services for users by service providers in Intelligent Transportation Systems(ITS).As IoV is a multi-user mobile scenario,the reliability and efficiency of data sharing need to be further enhanced.Federated learning allows the server to exchange parameters without obtaining private data from clients so that the privacy is protected.Broad learning system is a novel artificial intelligence technology that can improve training efficiency of data set.Thus,we propose a federated bidirectional connection broad learning scheme(FeBBLS)to solve the data sharing issues.Firstly,we adopt the bidirectional connection broad learning system(BiBLS)model to train data set in vehicular nodes.The server aggregates the collected parameters of BiBLS from vehicular nodes through the federated broad learning system(FedBLS)algorithm.Moreover,we propose a clustering FedBLS algorithm to offload the data sharing into clusters for improving the aggregation capability of the model.Some simulation results show our scheme can improve the efficiency and prediction accuracy of data sharing and protect the privacy of data sharing.展开更多
The backscattering signal, which arises from the pulsed laser traveling through water, has limited the lidar system sensitivity and underwater target contrast. The transmitted optical carrier is modulated to be ultras...The backscattering signal, which arises from the pulsed laser traveling through water, has limited the lidar system sensitivity and underwater target contrast. The transmitted optical carrier is modulated to be ultrashort pulsed laser and it is effective to suppress the backscattering to adopt the coherent detection technology by identifying the modulation envelope. A nonstationary light field is formed in seawater by the ultrashort pulsed laser. The inherent relationship between the nonstationary light field formed by modulated lidar and the stationary light field formed by conventional lidar was discussed and the backscattering light model of the stationary light field for the ultrashort pulsed laser was proposed. The backscattering signal in modulated lidar system was processed and analyzed in the frequency domain on the basis of the model.展开更多
This letter investigates a delay optimization problem in device-to-device(D2D)networks where users have pre-downloaded subfiles following a coded caching rule.Due to acquiring rest subfiles,users may suffer both recei...This letter investigates a delay optimization problem in device-to-device(D2D)networks where users have pre-downloaded subfiles following a coded caching rule.Due to acquiring rest subfiles,users may suffer both receiving and transmitting delays.To achieve the delay minimization,we first propose a delay-aware mode-selection strategy to adaptively choose multicast or D2D communications mode to reduce the receiving-caused delay.By matching these transmit modes with distinct subfile sizes,we further formulate a min-max optimization problem to minimize the delivery delay.Finally,numerical results prove that the proposed scheme outperforms existing ones in terms of both receiving and transmitting delays.展开更多
This paper presents techniques and approaches capable of achieving a real-time JPEG2000 compressing system using DSP chips. We propose a three-DSP real-time parallel processing system using efficient memory management...This paper presents techniques and approaches capable of achieving a real-time JPEG2000 compressing system using DSP chips. We propose a three-DSP real-time parallel processing system using efficient memory management for discrete wavelet transform (DWT) and parallel-pass architecture for embedded block coding with optimized truncation (EBCOT). This system performs compression of 1392×1040 pixels monochrome images with the speed of 10 fps/camera of 2 digital still cameras and is proven to be a practical and efficient DSP solution.展开更多
In this paper, we consider the optimal problem of channels sharing with het-erogeneous traffic （real-time service and non-real-time service） to reduce the data conflict probability of users. Moreover, a multi-dimens...In this paper, we consider the optimal problem of channels sharing with het-erogeneous traffic （real-time service and non-real-time service） to reduce the data conflict probability of users. Moreover, a multi-dimensional Markov chain model is developed to analyze the performance of the proposed scheme. Meanwhile, performance metrics are derived. Numerical results show that the proposed scheme can effectively reduce the forced termination probability, blocking probability and spectrum utilization.展开更多
This paper studies the cognitive broadcast channel in which the primary user communicates to the primary receiver, while the secondary user has noncausal knowledge of the primary radio's codeword and expects to co...This paper studies the cognitive broadcast channel in which the primary user communicates to the primary receiver, while the secondary user has noncausal knowledge of the primary radio's codeword and expects to communicate to two secondary receivers. Comparing with the existing cognitive radio channel which considers only one secondary receiver, cognitive broadcast channel studies the case that there are multiple secondary receivers.To this end, we investigate the fundamental limits of the performance of the Gaussian cognitive broadcast channel from the information theoretic perspective. Specifically, we derive the capacity region of the Gaussian cognitive degraded broadcast channel with weak interference.展开更多
Based on the theory of Duffing oscillator weak signal detection and the technology of extended binary phase shift keying （EBPSK） modulation, the chaotic demodulator using the Duffing oscillator for EBPSK signals was...Based on the theory of Duffing oscillator weak signal detection and the technology of extended binary phase shift keying （EBPSK） modulation, the chaotic demodulator using the Duffing oscillator for EBPSK signals was proposed. The proposed demodulator could avoid the problem of demodulation filters design, and shows the excellent anti-noise capability of chaotic oscillator detection. Numerical and experimental tests were taken to investigate the impact of modulation parameters T and 0 on bit error performance of the proposed method, and the performance limits were gotten. The results show that the proposed chaotic demodulator works well under a very low signal-to-noise ratio （SNR） conditions, and gets SNR gains about 20 dB to 30 dB from the impulse filter.展开更多
The multi-resolution adaptive grids method is proposed to solve the problems of inefficiency in the previous grid-based methods,and it can be used in clouds simulation as well as the interactive simulation between obj...The multi-resolution adaptive grids method is proposed to solve the problems of inefficiency in the previous grid-based methods,and it can be used in clouds simulation as well as the interactive simulation between objects and clouds.Oriented bounding box(OBB)hierarchical trees of objects are established,and the resolutions of global and local grids can be selected automatically.The motion equations of fluid dynamics are simplified.Upwind difference is applied to ensure the stability of the simulation process during the discrete process of partial differential equations.To solve the speed problem of existed phase functions,the improved phase function is applied to the illumination calculation of clouds.Experimental results show that the proposed methods can promote the simulation efficiency and meet the need for the simulation of large-scale clouds scene.Real-time rendering of clouds and the interaction between clouds and objects have been realized without preprocessing stage.展开更多
We report ab initio calculations of the transport behavior of a phenyl substituted molecular motor. The calculated results show that the transport behavior of the device is sensitive to the rotation degree of the roto...We report ab initio calculations of the transport behavior of a phenyl substituted molecular motor. The calculated results show that the transport behavior of the device is sensitive to the rotation degree of the rotor part. When the rotor part is parallel with the stator part, a better rectifying performance can be found in the current-voltage curve. However, when the rotor part revolves to vertical with the stator part, the currents in the positive bias region decrease slightly. More importantly, the rectifying performance disappears. Thus this offers us a new method to modulate the rectifying behavior in molecular devices.展开更多
Direct growth of redox-active noble metals and rational design of multifunctional electrochemical active materials play crucial roles in developing novel electrode materials for energy storage devices.In this regard,s...Direct growth of redox-active noble metals and rational design of multifunctional electrochemical active materials play crucial roles in developing novel electrode materials for energy storage devices.In this regard,silver(Ag)has attracted great attention in the design of efficient electrodes.Inspired by the house/building process,which means electing the right land,it lays a strong foundation and building essential columns for a complex structure.Herein,we report the construction of multifaceted heterostructure cobalt-iron hydroxide(CFOH)nanowires(NWs)@nickel cobalt manganese hydroxides and/or hydrate(NCMOH)nanosheets(NSs)on the Ag-deposited nickel foam and carbon cloth(i.e.,Ag/NF and Ag/CC)substrates.Moreover,the formation and charge storage mechanism of Ag are described,and these contribute to good conductive and redox chemistry features.The switching architectural integrity of metal and redox materials on metallic frames may significantly boost charge storage and rate performance with noticeable drop in resistance.The as-fabricated Ag@CFOH@NCMOH/NF electrode delivered superior areal capacity value of 2081.9μA h cm^(-2)at 5 mA cm^(-2).Moreover,as-assembled hybrid cell based on NF(HC/NF)device exhibited remarkable areal capacity value of 1.82 mA h cm^(-2)at 5 mA cm^(-2)with excellent rate capability of 74.77%even at 70 mA cm^(-2)Furthermore,HC/NF device achieved maximum energy and power densities of 1.39 mW h cm^(-2)and 42.35 mW cm^(-2),respectively.To verify practical applicability,both devices were also tested to serve as a self-charging station for various portable electronic devices.展开更多
A new quantum secure direct communication （QSDC） protocol is proposed by using decoherence free subspace （DFS） to avoid insecurity of the present QSDC protocols in a quantum noise channel. This protocol makes it e...A new quantum secure direct communication （QSDC） protocol is proposed by using decoherence free subspace （DFS） to avoid insecurity of the present QSDC protocols in a quantum noise channel. This protocol makes it easily for Bob and Alice to find eavesdropping in channel because the collective dephasing noise disappears in DFS. The probability of successful attack by Eve in this protocol is smaller than in BB84 protocol. Thus this protocol realizes secure QSDC and is feasible with present-day technology.展开更多
The pristine CeVO_(4) and CeVO_(4)/CNT hybrid composite nanostructured samples were facilely synthesized using a simple silicone oil-bath method.From the X-ray diffraction results,the formation of tetragonal CeVO_(4) ...The pristine CeVO_(4) and CeVO_(4)/CNT hybrid composite nanostructured samples were facilely synthesized using a simple silicone oil-bath method.From the X-ray diffraction results,the formation of tetragonal CeVO_(4) with an additional minor phase of V_(2)O_(5) was identified.When investigated as an anode material for lithium(Li)-ion batteries,the CeVO_(4)/CNT hybrid composite nanostructure(HCNS) electrode demonstrated improved Li storage performance over the pristine CeVO_(4).The Li insertion/de-insertion electrochemical reaction with the CeVO_(4) was analyzed on the basis of cyclic voltammetry study.The cyclic voltammetry analysis revealed that the three-step reduction of V^(5+) to V^(3+), V^(3+) to V^(2+), and V^(2+) to V+ processes is involved and among them,only V^(5+) to V^(3+) is reversible during the Li-ion insertion into CeVO_(4).The CeVO_(4)/CNT HCNS electrode exhibited a discharge capacity as high as 443 mA h g^(-1)(capacity retention of 96.3%) over 200 cycles at 100 mA g^(-1), whereas the pristine CeVO_(4) is limited to 138 mA h g^(-1)(capacity retention of 48%).Even at a high current density of 500 mA g^(-1), the CeVO_(4)/CNT HCNS electrode delivered an excellent reversible capacity of 586.82 mA h g^(-1) after 1200 cycles.展开更多
In this paper, we propose a classical secret broadcasting and splitting joint protocol in a quantum scenario. With those genuinely entangled states, the boss can always broadcast some of his secrets and split some oth...In this paper, we propose a classical secret broadcasting and splitting joint protocol in a quantum scenario. With those genuinely entangled states, the boss can always broadcast some of his secrets and split some others to multi- receivers at the same time. The efficiency of the joint protocol is also compared with that of two separate ones which realise classical secret broadcasting and classical secret splitting respectively, and based on the comparison we can see the promising advantage of our joint protocol is that it can realise the two tasks more efficiently and more conveniently.展开更多
In order to compensate the primary performance degradation,which is caused by the co-existing secondary communications or the heavy fading of primary link,a cooperative relay scheme is proposed in cognitive radio syst...In order to compensate the primary performance degradation,which is caused by the co-existing secondary communications or the heavy fading of primary link,a cooperative relay scheme is proposed in cognitive radio systems by taking advantage of the opportunities that are arisen by the primary ARQ(Automatic Repeat-reQuest)retransmission.With the help of this scheme,nontrivial relay assistances for the primary retransmission are achieved without initialization phase.The cooperation among secondary users provides additional spatial diversity to facilitate the primary transmission.This can be accomplished with an oblivious primary system and without assuming any non-causal information about the primary data.The scheme are further extended to the scenarios where multiple cognitive pairs exist.Performance analyses of the schemes are devised and the effectiveness is verified via simulations.展开更多
Identifying influential nodes in complex networks is of both theoretical and practical importance. Existing methods identify influential nodes based on their positions in the network and assume that the nodes are homo...Identifying influential nodes in complex networks is of both theoretical and practical importance. Existing methods identify influential nodes based on their positions in the network and assume that the nodes are homogeneous. However, node heterogeneity （i.e., different attributes such as interest, energy, age, and so on ） ubiquitously exists and needs to be taken into consideration. In this paper, we conduct an investigation into node attributes and propose a graph signal pro- cessing based centrality （GSPC） method to identify influential nodes considering both the node attributes and the network topology. We first evaluate our GSPC method using two real-world datasets. The results show that our GSPC method effectively identifies influential nodes, which correspond well with the underlying ground truth. This is compatible to the previous eigenvector centrality and principal component centrality methods under circumstances where the nodes are homogeneous. In addition, spreading analysis shows that the GSPC method has a positive effect on the spreading dynamics.展开更多
This paper investigates the content placement problem to maximize the cache hit ratio in device-to-device(D2D)communications overlaying cellular networks.We consider offloading contents by users themselves,D2D communi...This paper investigates the content placement problem to maximize the cache hit ratio in device-to-device(D2D)communications overlaying cellular networks.We consider offloading contents by users themselves,D2D communications and multicast,and we analyze the relationship between these offloading methods and the cache hit ratio.Based on this relationship,we formulate the content placement optimization as a cache hit ratio maximization problem,and propose a heuristic algorithm to solve it.Numerical results demonstrate that the proposed scheme can outperform existing schemes in terms of the cache hit ratio.展开更多
基金supported by the National Research Foundation of Korea Grant funded by the Korean government(MSIP)(No.2018R1A6A1A03025708).
文摘The undesirable dendrite growth induced by non-planar zinc(Zn)deposition and low Coulombic efficiency resulting from severe side reactions have been long-standing challenges for metallic Zn anodes and substantially impede the practical application of rechargeable aqueous Zn metal batteries(ZMBs).Herein,we present a strategy for achieving a high-rate and long-cycle-life Zn metal anode by patterning Zn foil surfaces and endowing a Zn-Indium(Zn-In)interface in the microchannels.The accumulation of electrons in the microchannel and the zincophilicity of the Zn-In interface promote preferential heteroepitaxial Zn deposition in the microchannel region and enhance the tolerance of the electrode at high current densities.Meanwhile,electron aggregation accelerates the dissolution of non-(002)plane Zn atoms on the array surface,thereby directing the subsequent homoepitaxial Zn deposition on the array surface.Consequently,the planar dendrite-free Zn deposition and long-term cycling stability are achieved(5,050 h at 10.0 mA cm^(−2) and 27,000 cycles at 20.0 mA cm^(−2)).Furthermore,a Zn/I_(2) full cell assembled by pairing with such an anode can maintain good stability for 3,500 cycles at 5.0 C,demonstrating the application potential of the as-prepared ZnIn anode for high-performance aqueous ZMBs.
文摘Correction to:Nano-Micro Letters(2024)16:112 https://doi.org/10.1007/s40820-024-01327-2 In the supplementary information the following corrections have been carried out:1.Institute of Energy and Climate Research,Materials Synthesis and Processing,Forschungszentrum Jülich GmbH,52425 Jülich,Germany.Corrected:Institute of Energy and Climate Research:Materials Synthesis and Processing(IEK-1),Forschungszentrum Jülich GmbH,52425 Jülich,Germany.
基金supported by the National Natural Science Foundation of China（11371027） the Projects of Outstanding Young Talents of Universities in Anhui Province（gxyq2018116）+2 种基金 the Teaching Groups in Anhui Province（2016jxtd080,2015jxtd048） the NSF of Educational Bureau of Anhui Province（KJ2017A702,KJ2017A704） the NSF of Bozhou University（BZSZKYXM201302,BSKY201539）
文摘In this paper, the existence and uniqueness of almost periodic solutions for some infinite delay integral equations are discussed. By using Krasnoselskii fixed point theorem,some new results are obtained.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60971009 and 61001011)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090142110019)+1 种基金the Natural Science Foundation of Hubei Province, China (Grant No. 2010CDB02701)the Fundamental Research Funds for the Central Universities, China (Grant No. 2012QN083)
文摘Decoupling the complicated vibrational-vibrational （V-V） coupling of a multimode vibrational relaxation remains a challenge for analyzing the sound relaxational absorption in multi-component gas mixtures. In our previous work [Acta Phys. Sin. 61 174301 （2012）], an analytical model to predict the sound absorption from vibrational relaxation in a gas medium is proposed. In this paper, we develop the model to decouple the V-V coupled energy to each vibrationaltranslational deexcitation path, and analyze how the multimode relaxations form the peaks of sound absorption spectra in gas mixtures. We prove that a multimode relaxation is the sum of its decoupled single-relaxation processes, and only the decoupled process with a significant isochoric-molar-heat can be observed as an absorption peak. The decoupling model clarifies the essential processes behind the peaks in spectra arising from the multimode relaxations in multi-component gas mixtures. The simulation validates the proposed decoupling model.
基金supported by the National Natural Science Foundation of China under Grant No.61901099, 61972076, 61973069 and 62061006the Natural Science Foundation of Hebei Province under Grant No.F2020501037the Natural Science Foundation of Guangxi under Grant No.2018JJA170167
文摘Data sharing in Internet of Vehicles(IoV)makes it possible to provide personalized services for users by service providers in Intelligent Transportation Systems(ITS).As IoV is a multi-user mobile scenario,the reliability and efficiency of data sharing need to be further enhanced.Federated learning allows the server to exchange parameters without obtaining private data from clients so that the privacy is protected.Broad learning system is a novel artificial intelligence technology that can improve training efficiency of data set.Thus,we propose a federated bidirectional connection broad learning scheme(FeBBLS)to solve the data sharing issues.Firstly,we adopt the bidirectional connection broad learning system(BiBLS)model to train data set in vehicular nodes.The server aggregates the collected parameters of BiBLS from vehicular nodes through the federated broad learning system(FedBLS)algorithm.Moreover,we propose a clustering FedBLS algorithm to offload the data sharing into clusters for improving the aggregation capability of the model.Some simulation results show our scheme can improve the efficiency and prediction accuracy of data sharing and protect the privacy of data sharing.
文摘The backscattering signal, which arises from the pulsed laser traveling through water, has limited the lidar system sensitivity and underwater target contrast. The transmitted optical carrier is modulated to be ultrashort pulsed laser and it is effective to suppress the backscattering to adopt the coherent detection technology by identifying the modulation envelope. A nonstationary light field is formed in seawater by the ultrashort pulsed laser. The inherent relationship between the nonstationary light field formed by modulated lidar and the stationary light field formed by conventional lidar was discussed and the backscattering light model of the stationary light field for the ultrashort pulsed laser was proposed. The backscattering signal in modulated lidar system was processed and analyzed in the frequency domain on the basis of the model.
基金partly supported by the National Natural Science Foundation of China (No.61601334,61601509)
文摘This letter investigates a delay optimization problem in device-to-device(D2D)networks where users have pre-downloaded subfiles following a coded caching rule.Due to acquiring rest subfiles,users may suffer both receiving and transmitting delays.To achieve the delay minimization,we first propose a delay-aware mode-selection strategy to adaptively choose multicast or D2D communications mode to reduce the receiving-caused delay.By matching these transmit modes with distinct subfile sizes,we further formulate a min-max optimization problem to minimize the delivery delay.Finally,numerical results prove that the proposed scheme outperforms existing ones in terms of both receiving and transmitting delays.
文摘This paper presents techniques and approaches capable of achieving a real-time JPEG2000 compressing system using DSP chips. We propose a three-DSP real-time parallel processing system using efficient memory management for discrete wavelet transform (DWT) and parallel-pass architecture for embedded block coding with optimized truncation (EBCOT). This system performs compression of 1392×1040 pixels monochrome images with the speed of 10 fps/camera of 2 digital still cameras and is proven to be a practical and efficient DSP solution.
基金supported in part by the National Natural Science Foundation of China(60972016,61231010)the Funds of Distinguished Young Scientists(2009CDA150)+1 种基金China-Finnish Cooperation Project(2010DFB10570)Specialized Research Fund for the Doctoral Program of Higher Education(20120142110015)
文摘In this paper, we consider the optimal problem of channels sharing with het-erogeneous traffic （real-time service and non-real-time service） to reduce the data conflict probability of users. Moreover, a multi-dimensional Markov chain model is developed to analyze the performance of the proposed scheme. Meanwhile, performance metrics are derived. Numerical results show that the proposed scheme can effectively reduce the forced termination probability, blocking probability and spectrum utilization.
基金supported by the Project-Sponsored by SRF for ROCS,SEMthe National Science and Technology Major Project of the Ministry of Science and Technologyof China under Grants No.2012ZX03003004,No.2010ZX03006002+2 种基金the National Natural Science Foundation of China under Grants No.61172052,No.61261046the Scientific Research Foundation of the Higher Education Institutions of Guangxi under Grant No.201203YB159Wuzhou University Foundation under Grant No.2012B001
文摘This paper studies the cognitive broadcast channel in which the primary user communicates to the primary receiver, while the secondary user has noncausal knowledge of the primary radio's codeword and expects to communicate to two secondary receivers. Comparing with the existing cognitive radio channel which considers only one secondary receiver, cognitive broadcast channel studies the case that there are multiple secondary receivers.To this end, we investigate the fundamental limits of the performance of the Gaussian cognitive broadcast channel from the information theoretic perspective. Specifically, we derive the capacity region of the Gaussian cognitive degraded broadcast channel with weak interference.
基金supported by the National Natural Science Foundation of China under Grant No.41476089
文摘Based on the theory of Duffing oscillator weak signal detection and the technology of extended binary phase shift keying （EBPSK） modulation, the chaotic demodulator using the Duffing oscillator for EBPSK signals was proposed. The proposed demodulator could avoid the problem of demodulation filters design, and shows the excellent anti-noise capability of chaotic oscillator detection. Numerical and experimental tests were taken to investigate the impact of modulation parameters T and 0 on bit error performance of the proposed method, and the performance limits were gotten. The results show that the proposed chaotic demodulator works well under a very low signal-to-noise ratio （SNR） conditions, and gets SNR gains about 20 dB to 30 dB from the impulse filter.
基金supported by the National Natural Science Foundation of China(No.61102167)
文摘The multi-resolution adaptive grids method is proposed to solve the problems of inefficiency in the previous grid-based methods,and it can be used in clouds simulation as well as the interactive simulation between objects and clouds.Oriented bounding box(OBB)hierarchical trees of objects are established,and the resolutions of global and local grids can be selected automatically.The motion equations of fluid dynamics are simplified.Upwind difference is applied to ensure the stability of the simulation process during the discrete process of partial differential equations.To solve the speed problem of existed phase functions,the improved phase function is applied to the illumination calculation of clouds.Experimental results show that the proposed methods can promote the simulation efficiency and meet the need for the simulation of large-scale clouds scene.Real-time rendering of clouds and the interaction between clouds and objects have been realized without preprocessing stage.
基金Supported by the Science and Technology Plan of Hunan Province under Grant No 2014SK3274
文摘We report ab initio calculations of the transport behavior of a phenyl substituted molecular motor. The calculated results show that the transport behavior of the device is sensitive to the rotation degree of the rotor part. When the rotor part is parallel with the stator part, a better rectifying performance can be found in the current-voltage curve. However, when the rotor part revolves to vertical with the stator part, the currents in the positive bias region decrease slightly. More importantly, the rectifying performance disappears. Thus this offers us a new method to modulate the rectifying behavior in molecular devices.
基金supported by the National Research Foundation of Korea (NRF)grant funded by the Korean government (MSIP) (2018R1A6A1A03025708)。
文摘Direct growth of redox-active noble metals and rational design of multifunctional electrochemical active materials play crucial roles in developing novel electrode materials for energy storage devices.In this regard,silver(Ag)has attracted great attention in the design of efficient electrodes.Inspired by the house/building process,which means electing the right land,it lays a strong foundation and building essential columns for a complex structure.Herein,we report the construction of multifaceted heterostructure cobalt-iron hydroxide(CFOH)nanowires(NWs)@nickel cobalt manganese hydroxides and/or hydrate(NCMOH)nanosheets(NSs)on the Ag-deposited nickel foam and carbon cloth(i.e.,Ag/NF and Ag/CC)substrates.Moreover,the formation and charge storage mechanism of Ag are described,and these contribute to good conductive and redox chemistry features.The switching architectural integrity of metal and redox materials on metallic frames may significantly boost charge storage and rate performance with noticeable drop in resistance.The as-fabricated Ag@CFOH@NCMOH/NF electrode delivered superior areal capacity value of 2081.9μA h cm^(-2)at 5 mA cm^(-2).Moreover,as-assembled hybrid cell based on NF(HC/NF)device exhibited remarkable areal capacity value of 1.82 mA h cm^(-2)at 5 mA cm^(-2)with excellent rate capability of 74.77%even at 70 mA cm^(-2)Furthermore,HC/NF device achieved maximum energy and power densities of 1.39 mW h cm^(-2)and 42.35 mW cm^(-2),respectively.To verify practical applicability,both devices were also tested to serve as a self-charging station for various portable electronic devices.
文摘A new quantum secure direct communication （QSDC） protocol is proposed by using decoherence free subspace （DFS） to avoid insecurity of the present QSDC protocols in a quantum noise channel. This protocol makes it easily for Bob and Alice to find eavesdropping in channel because the collective dephasing noise disappears in DFS. The probability of successful attack by Eve in this protocol is smaller than in BB84 protocol. Thus this protocol realizes secure QSDC and is feasible with present-day technology.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIP)(No.2018R1A6A1A03025708 and No.2020R1A2B5B01002318)。
文摘The pristine CeVO_(4) and CeVO_(4)/CNT hybrid composite nanostructured samples were facilely synthesized using a simple silicone oil-bath method.From the X-ray diffraction results,the formation of tetragonal CeVO_(4) with an additional minor phase of V_(2)O_(5) was identified.When investigated as an anode material for lithium(Li)-ion batteries,the CeVO_(4)/CNT hybrid composite nanostructure(HCNS) electrode demonstrated improved Li storage performance over the pristine CeVO_(4).The Li insertion/de-insertion electrochemical reaction with the CeVO_(4) was analyzed on the basis of cyclic voltammetry study.The cyclic voltammetry analysis revealed that the three-step reduction of V^(5+) to V^(3+), V^(3+) to V^(2+), and V^(2+) to V+ processes is involved and among them,only V^(5+) to V^(3+) is reversible during the Li-ion insertion into CeVO_(4).The CeVO_(4)/CNT HCNS electrode exhibited a discharge capacity as high as 443 mA h g^(-1)(capacity retention of 96.3%) over 200 cycles at 100 mA g^(-1), whereas the pristine CeVO_(4) is limited to 138 mA h g^(-1)(capacity retention of 48%).Even at a high current density of 500 mA g^(-1), the CeVO_(4)/CNT HCNS electrode delivered an excellent reversible capacity of 586.82 mA h g^(-1) after 1200 cycles.
文摘In this paper, we propose a classical secret broadcasting and splitting joint protocol in a quantum scenario. With those genuinely entangled states, the boss can always broadcast some of his secrets and split some others to multi- receivers at the same time. The efficiency of the joint protocol is also compared with that of two separate ones which realise classical secret broadcasting and classical secret splitting respectively, and based on the comparison we can see the promising advantage of our joint protocol is that it can realise the two tasks more efficiently and more conveniently.
基金supported by the National Natural Science Foundation of China (No.61601334,61601509)
文摘In order to compensate the primary performance degradation,which is caused by the co-existing secondary communications or the heavy fading of primary link,a cooperative relay scheme is proposed in cognitive radio systems by taking advantage of the opportunities that are arisen by the primary ARQ(Automatic Repeat-reQuest)retransmission.With the help of this scheme,nontrivial relay assistances for the primary retransmission are achieved without initialization phase.The cooperation among secondary users provides additional spatial diversity to facilitate the primary transmission.This can be accomplished with an oblivious primary system and without assuming any non-causal information about the primary data.The scheme are further extended to the scenarios where multiple cognitive pairs exist.Performance analyses of the schemes are devised and the effectiveness is verified via simulations.
基金supported by the National Natural Science Foundation of China(Grant No.61231010)the Fundamental Research Funds for the Central Universities,China(Grant No.HUST No.2012QN076)
文摘Identifying influential nodes in complex networks is of both theoretical and practical importance. Existing methods identify influential nodes based on their positions in the network and assume that the nodes are homogeneous. However, node heterogeneity （i.e., different attributes such as interest, energy, age, and so on ） ubiquitously exists and needs to be taken into consideration. In this paper, we conduct an investigation into node attributes and propose a graph signal pro- cessing based centrality （GSPC） method to identify influential nodes considering both the node attributes and the network topology. We first evaluate our GSPC method using two real-world datasets. The results show that our GSPC method effectively identifies influential nodes, which correspond well with the underlying ground truth. This is compatible to the previous eigenvector centrality and principal component centrality methods under circumstances where the nodes are homogeneous. In addition, spreading analysis shows that the GSPC method has a positive effect on the spreading dynamics.
基金partly supported by the Na-tional Natural Science Foundation of China (No.61601334,61601509)
文摘This paper investigates the content placement problem to maximize the cache hit ratio in device-to-device(D2D)communications overlaying cellular networks.We consider offloading contents by users themselves,D2D communications and multicast,and we analyze the relationship between these offloading methods and the cache hit ratio.Based on this relationship,we formulate the content placement optimization as a cache hit ratio maximization problem,and propose a heuristic algorithm to solve it.Numerical results demonstrate that the proposed scheme can outperform existing schemes in terms of the cache hit ratio.
