Great photoelectric properties can herald the high potentials of CsPbBr3 nanocrystals(NCs)to function as the fluorescent probes for early tumor diagnosis.However,the intrinsic water vulnerability of CsPbBr3 NCs highly...Great photoelectric properties can herald the high potentials of CsPbBr3 nanocrystals(NCs)to function as the fluorescent probes for early tumor diagnosis.However,the intrinsic water vulnerability of CsPbBr3 NCs highly restricts their biomedical applications.To conquer this challenge,we herein introduce a nature inspired"stress-response"method to tightly encapsulate CsPbBr3 into SiO2 nano-shells that can dramatically improve the water stability of CsPbBr3@SiO2 nanoparticles for over 48 h.We further highlighted the advantageous features of CsPbBr3@SiO2 by using them as the fluorescent probes for CT26 tumor cell imaging with their high water stability,biocompatibility,and low cytotoxicity.Our work for the first time exhibited the potential of lead halide perovskite NCs for tumor diagnosis,and can highly anticipate the further in vivo biomedical applications that light up live cells.展开更多
The application of Non-Orthogonal Multiple Access(NOMA) technology into satelliteaerial-ground integrated networks can meet the requirements of ultra-high rate and massive connectivity for the Sixth-Generation(6G) com...The application of Non-Orthogonal Multiple Access(NOMA) technology into satelliteaerial-ground integrated networks can meet the requirements of ultra-high rate and massive connectivity for the Sixth-Generation(6G) communication systems. We consider an uplink NOMA scenario for such a satellite-aerial-ground integrated network where multiple users communicate with satellite under the help of an Unmanned Aerial Vehicle(UAV) as an aerial relay equipped with a phased array. Supposing that buffer-aided decode-and-forward protocol is adopted at the UAV relay, we first formulate an optimization problem to maximize Ergodic Sum Rate(ESR) of the considered system subject to individual power constraint and quality-of-service constraint of each user.Then, with known imperfect channel state information of each user, we propose a joint power allocation and robust Beam Forming(BF) iterative algorithm to maximize ESR for the user-to-UAV link. Besides, to take the advantages of Free-Space Optical(FSO) and millimeter Wave(mmWave)communications, we present a switch-based hybrid FSO/mmWave scheme and a robust BF algorithm for the UAV-to-satellite link to achieve higher rate. Moreover, a closed-form ESR expression is derived. Finally, the effectiveness and correctness of the proposed solutions are verified by numerical simulations, and the performance evaluation results show that the proposed solutions not only achieve performance enhancement and robustness, but also outperform the orthogonal multiple access significantly.展开更多
The scale and complexity of big data are growing continuously,posing severe challenges to traditional data processing methods,especially in the field of clustering analysis.To address this issue,this paper introduces ...The scale and complexity of big data are growing continuously,posing severe challenges to traditional data processing methods,especially in the field of clustering analysis.To address this issue,this paper introduces a new method named Big Data Tensor Multi-Cluster Distributed Incremental Update(BDTMCDIncreUpdate),which combines distributed computing,storage technology,and incremental update techniques to provide an efficient and effective means for clustering analysis.Firstly,the original dataset is divided into multiple subblocks,and distributed computing resources are utilized to process the sub-blocks in parallel,enhancing efficiency.Then,initial clustering is performed on each sub-block using tensor-based multi-clustering techniques to obtain preliminary results.When new data arrives,incremental update technology is employed to update the core tensor and factor matrix,ensuring that the clustering model can adapt to changes in data.Finally,by combining the updated core tensor and factor matrix with historical computational results,refined clustering results are obtained,achieving real-time adaptation to dynamic data.Through experimental simulation on the Aminer dataset,the BDTMCDIncreUpdate method has demonstrated outstanding performance in terms of accuracy(ACC)and normalized mutual information(NMI)metrics,achieving an accuracy rate of 90%and an NMI score of 0.85,which outperforms existing methods such as TClusInitUpdate and TKLClusUpdate in most scenarios.Therefore,the BDTMCDIncreUpdate method offers an innovative solution to the field of big data analysis,integrating distributed computing,incremental updates,and tensor-based multi-clustering techniques.It not only improves the efficiency and scalability in processing large-scale high-dimensional datasets but also has been validated for its effectiveness and accuracy through experiments.This method shows great potential in real-world applications where dynamic data growth is common,and it is of significant importance for advancing the development of data an展开更多
To investigate the environmental impacts of steel deck pavement through the whole life cycle,the steel deck pavement was divided into five stages:raw materials production,asphalt mixture mixing,pavement construction,o...To investigate the environmental impacts of steel deck pavement through the whole life cycle,the steel deck pavement was divided into five stages:raw materials production,asphalt mixture mixing,pavement construction,operation management,and pavement removing stage.Based on the process-based life cycle assessment(PLCA)method,the calculation methods of energy consumption and gas emissions of two typical steel deck pavement systems(EA+EA pavement and GA+SMA pavement)were determined.The data lists of two pavements were analyzed,and the calculation model was built.Four characteristic indices including primary energy demand(PED),global warming potential(GWP),acidification potential(AP)and respiratory inorganics(RI)were used to quantify the environmental impacts of two pavements.The results show that the environmental impact of the GA+SMA pavement is more than 1.3 times that of the EA+EA pavement.Moreover,the critical stage of energy-saving and emission-reduction of EA+EA pavement and GA+SMA pavement are the raw material production stage and asphalt mixture mixing stage,respectively.展开更多
Short-term prediction of on-street parking occupancy is essential to the ITS system,which can guide drivers in finding vacant parking spaces.And the spatial dependencies and exogenous dependencies need to be considere...Short-term prediction of on-street parking occupancy is essential to the ITS system,which can guide drivers in finding vacant parking spaces.And the spatial dependencies and exogenous dependencies need to be considered simultaneously,which makes short-term prediction of on-street parking occupancy challenging.Therefore,this paper proposes a deep learning model for predicting block-level parking occupancy.First,the importance of multiple points of interest(POI)in different buffers is sorted by Boruta,used for feature selection.The results show that different types of POI data should consider different buffer radii.Then based on the real on-street parking data,long short-term memory(LSTM)that can address the time dependencies is applied to predict the parking occupancy.The results demonstrate that LSTM considering POI data after Boruta selection(LSTM(+BORUTA))outperforms other baseline methods,including LSTM,with an average testing MAPE of 11.78%.The selection process of POI data helps LSTM reduce training time and slightly improve the prediction performance,which indicates that complex correlations among the same type of POI data in different buffer zones will also affect the prediction accuracy of LSTM.When there are more restaurants on both sides of the street,the prediction performance of LSTM(+BORUTA)is significantly better than that of LSTM.展开更多
The global spread of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)requires an urgent need to find effective therapeutics for the treatment of coronavirus disease 2019(COVID-19).In this study,we developed...The global spread of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)requires an urgent need to find effective therapeutics for the treatment of coronavirus disease 2019(COVID-19).In this study,we developed an integrative drug repositioning framework,which fully takes advantage of machine learning and statistical analysis approaches to systematically integrate and mine large-scale knowledge graph,literature and transcriptome data to discover the potential drug candidates against SARS-CoV-2.Our in silico screening followed by wet-lab validation indicated that a poly-ADP-ribose polymerase 1(PARP1)inhibitor,CVL218,currently in Phase I clinical trial,may be repurposed to treat COVID-19.Our in vitro assays revealed that CVL218 can exhibit effective inhibitory activity against SARS-CoV-2 replication without obvious cytopathic effect.In addition,we showed that CVL218 can interact with the nucleocapsid(N)protein of SARS-CoV-2 and is able to suppress the LPS-induced production of several inflammatory cytokines that are highly relevant to the prevention of immunopathology induced by SARS-CoV-2 infection.展开更多
In current wireless communication and electronic systems,digital signals and electromagnetic(EM)radiation are processed by different modules.Here,we propose a mechanism to fuse the modulation of digital signals and th...In current wireless communication and electronic systems,digital signals and electromagnetic(EM)radiation are processed by different modules.Here,we propose a mechanism to fuse the modulation of digital signals and the manipulation of EM radiation on a single programmable metasurface(PM).The PM consists of massive subwavelength-scale digital coding elements.A set of digital states of all elements forms simultaneous digital information roles for modulation and the wave-control sequence code of the PM.By designing digital coding sequences in the spatial and temporal domains,the digital information and farfield patterns of the PM can be programmed simultaneously and instantly in desired ways.For the experimental demonstration of the mechanism,we present a programmable wireless communication system.The same system can realize transmissions of digital information in single-channel modes with beamsteerable capability and multichannel modes with multiple independent information.The measured results show the excellent performance of the programmable system.This work provides excellent prospects for applications in fifth-or sixth-generation wireless communications and modern intelligent platforms for unmanned aircrafts and vehicles.展开更多
In order to take advantage of the asynchronous sensing information, alleviate the sensing overhead of secondary users （SUs） and improve the detection performance, a sensor node-assisted asynchronous cooperative spec...In order to take advantage of the asynchronous sensing information, alleviate the sensing overhead of secondary users （SUs） and improve the detection performance, a sensor node-assisted asynchronous cooperative spectrum sensing （SN-ACSS） scheme for cognitive radio （CR） network （CRN） was proposed. In SN-ACSS, each SU is surrounded by sensor nodes （SNs）, which asynchronously make hard decisions and soft decisions based on the Bayesian fusion rule instead of the SU. The SU combines these soft decisions and makes the local soft decision. Finally, the fusion center （FC） fuses the local soft decisions transmitted from SUs with different weight coefficients to attain the final soft decision. Besides, the impact of the statistics of licensed band occupancy on detection performance and the fact that different SNs have different sensing contributions are also considered in SN-ACSS scheme. Numerical results show that compared with the conventional synchronous cooperative spectrum sensing （SCSS） and the existing ACSS schemes, SN-ACSS algorithm achieves a better detection performance and lower cost with the same number of SNs.展开更多
Flexible energy devices are the building blocks for next-generation wearable electronics.Flexible energy devices are expected to have multiple functions,such as energy conversion from light to electricity and vice ver...Flexible energy devices are the building blocks for next-generation wearable electronics.Flexible energy devices are expected to have multiple functions,such as energy conversion from light to electricity and vice versa,energy generation from triboelectric,energy storage and so on.These functions can be efficiently realized by solar cells,light-emitting diodes(LEDs),triboelectric nanogenerators(TENG),batteries and supercapacitors,etc.The flexible energy devices can be integrated into flexible,wearable,and/or portable platforms to enable wide application prospects in the fields of information,energy,medical care,national defense,etc.However,flexible energy devices face more challenges when compared to their rigid counterparts,which requires more breakthroughs and research efforts on fabrication techniques,materials innovation,novel structure designs,and deep physical understandings.展开更多
Magnesium alloy Mg-3%Al-1%Zn （AZ31） billets prepared from equal channel angular pressing （ECAP） were utilized in low-cycle fatigue tests in order to investigate their fatigue life. Fully reversed strain-controlled...Magnesium alloy Mg-3%Al-1%Zn （AZ31） billets prepared from equal channel angular pressing （ECAP） were utilized in low-cycle fatigue tests in order to investigate their fatigue life. Fully reversed strain-controlled tension-compression fatigue tests were conducted at the frequency of 1 Hz in ambient air. The microstructures were examined by optical microscopy （OM） and scanning electron microscopy （SEM）. The hysteresis loops of the ECAP processed and conventionally extruded samples display obviously different shapes in the total strain amplitude range from 0.2% to 0.6%. Accordingly, the low cycle fatigue lives of ECAP processed samples are found to be longer than those of extruded samples, which can be attributed to the different in the hysteresis energy incorporating tensile strain energy.展开更多
In the era of big data,the conflict between data mining and data privacy protection is increasing day by day.Traditional information security focuses on protecting the security of attribute values without semantic ass...In the era of big data,the conflict between data mining and data privacy protection is increasing day by day.Traditional information security focuses on protecting the security of attribute values without semantic association.The data privacy of big data is mainly reflected in the effective use of data without exposing the user’s sensitive information.Considering the semantic association,reasonable security access for privacy protect is required.Semi-structured and self-descriptive XML(eXtensible Markup Language)has become a common form of data organization for database management in big data environments.Based on the semantic integration nature of XML data,this paper proposes a data access control model for individual users.Through the semantic dependency between data and the integration process from bottom to top,the global visual range of inverted XML structure is realized.Experimental results show that the model effectively protects the privacy and has high access efficiency.展开更多
In 2020,the world has faced unprecedented challenges in human history with the Covid-19 pandemic,but communication systems and technologies have helped tremendously for teleworking and teleconferences.The progress of ...In 2020,the world has faced unprecedented challenges in human history with the Covid-19 pandemic,but communication systems and technologies have helped tremendously for teleworking and teleconferences.The progress of new technologies,particularly for satellite communication systems and applications,is facilitating the global coverage.展开更多
By comparing Love Actually and Pretty Woman,the two representatives of romance comedy,it is not difficult to arrive at the conclusion that UK romance comedy is more realism while the other is more idealism.It more or ...By comparing Love Actually and Pretty Woman,the two representatives of romance comedy,it is not difficult to arrive at the conclusion that UK romance comedy is more realism while the other is more idealism.It more or less has something related to the different cultures and national characters between the US and the UK.展开更多
The Adventure of Huckleberry Finn,one of Mark Twain’s masterpieces,is a story about a little child who pursues freedom together with his friend;however,if readers take it as easy as a fairy tale they will not really ...The Adventure of Huckleberry Finn,one of Mark Twain’s masterpieces,is a story about a little child who pursues freedom together with his friend;however,if readers take it as easy as a fairy tale they will not really understand it.When exploring it deeply it is noticed that the book reveals profound social problems and interpersonal relationships.展开更多
Multimedia teaching managemem system based on SIP ＆ P2P is proposed on account of the existing deficiency on video teaching of distance education. The designed P2P-SIP system applies SIP protocol to realize the under...Multimedia teaching managemem system based on SIP ＆ P2P is proposed on account of the existing deficiency on video teaching of distance education. The designed P2P-SIP system applies SIP protocol to realize the underlying DHT, which guarantees zero-configuration, robustness and adaptability in P2P system. And maximum improvement in performance of the networks for multimedia system can be implemented by rapid networking and information sharing technology of the underlying P2P networks as well as fast call and location technology of SIP system. Experiments indicates that multimedia teaching management system based on SIP ＆ P2P could meet the requirement of system design on data latency and calling location.展开更多
基金supported in part by the National Natural Science Foundation of China (No.71071161)the National Science Fund for Distinguished Young Scholars of China (No.70625005)
基金This work was supported primarily by the National Key Research and Development Program of China(No.2018YFE0208500)the Major Research Plan of the National Natural Science Foundation of China(No.91963206)+3 种基金the National Natural Science Foundation of China(Nos.U1508202 and 51627810)the Natural Science Foundation of Jiangsu Province(No.SBK2018022120),the open fund of Wuhan National Laboratory for Optoelectronics(No.2018WNLOKF020)the open fund of Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies(No.EEST2018-1)the civil aerospace technology preliminary research project of the State Administration of Science,Technology and Industry for National Defense.
文摘Great photoelectric properties can herald the high potentials of CsPbBr3 nanocrystals(NCs)to function as the fluorescent probes for early tumor diagnosis.However,the intrinsic water vulnerability of CsPbBr3 NCs highly restricts their biomedical applications.To conquer this challenge,we herein introduce a nature inspired"stress-response"method to tightly encapsulate CsPbBr3 into SiO2 nano-shells that can dramatically improve the water stability of CsPbBr3@SiO2 nanoparticles for over 48 h.We further highlighted the advantageous features of CsPbBr3@SiO2 by using them as the fluorescent probes for CT26 tumor cell imaging with their high water stability,biocompatibility,and low cytotoxicity.Our work for the first time exhibited the potential of lead halide perovskite NCs for tumor diagnosis,and can highly anticipate the further in vivo biomedical applications that light up live cells.
基金co-supported by the Key International Cooperation Research Project,China(No.61720106003)Jiangsu Province Science and Technology Project,China(No.BE2021031)+4 种基金the Shanghai Aerospace Science and Technology Innovation Foundation,China(No.SAST2019-095)NUPTSF(No.NY220111)the Research Project of Science and Technology on Complex Electronic System Simulation Laboratory,China(No.DXZT-JC-ZZ-2019-009)the National Natural Science Foundation of China(No.61801234)the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(No.KYCX210739)。
文摘The application of Non-Orthogonal Multiple Access(NOMA) technology into satelliteaerial-ground integrated networks can meet the requirements of ultra-high rate and massive connectivity for the Sixth-Generation(6G) communication systems. We consider an uplink NOMA scenario for such a satellite-aerial-ground integrated network where multiple users communicate with satellite under the help of an Unmanned Aerial Vehicle(UAV) as an aerial relay equipped with a phased array. Supposing that buffer-aided decode-and-forward protocol is adopted at the UAV relay, we first formulate an optimization problem to maximize Ergodic Sum Rate(ESR) of the considered system subject to individual power constraint and quality-of-service constraint of each user.Then, with known imperfect channel state information of each user, we propose a joint power allocation and robust Beam Forming(BF) iterative algorithm to maximize ESR for the user-to-UAV link. Besides, to take the advantages of Free-Space Optical(FSO) and millimeter Wave(mmWave)communications, we present a switch-based hybrid FSO/mmWave scheme and a robust BF algorithm for the UAV-to-satellite link to achieve higher rate. Moreover, a closed-form ESR expression is derived. Finally, the effectiveness and correctness of the proposed solutions are verified by numerical simulations, and the performance evaluation results show that the proposed solutions not only achieve performance enhancement and robustness, but also outperform the orthogonal multiple access significantly.
基金sponsored by the National Natural Science Foundation of China(Nos.61972208,62102194 and 62102196)National Natural Science Foundation of China(Youth Project)(No.62302237)+3 种基金Six Talent Peaks Project of Jiangsu Province(No.RJFW-111),China Postdoctoral Science Foundation Project(No.2018M640509)Postgraduate Research and Practice Innovation Program of Jiangsu Province(Nos.KYCX22_1019,KYCX23_1087,KYCX22_1027,KYCX23_1087,SJCX24_0339 and SJCX24_0346)Innovative Training Program for College Students of Nanjing University of Posts and Telecommunications(No.XZD2019116)Nanjing University of Posts and Telecommunications College Students Innovation Training Program(Nos.XZD2019116,XYB2019331).
文摘The scale and complexity of big data are growing continuously,posing severe challenges to traditional data processing methods,especially in the field of clustering analysis.To address this issue,this paper introduces a new method named Big Data Tensor Multi-Cluster Distributed Incremental Update(BDTMCDIncreUpdate),which combines distributed computing,storage technology,and incremental update techniques to provide an efficient and effective means for clustering analysis.Firstly,the original dataset is divided into multiple subblocks,and distributed computing resources are utilized to process the sub-blocks in parallel,enhancing efficiency.Then,initial clustering is performed on each sub-block using tensor-based multi-clustering techniques to obtain preliminary results.When new data arrives,incremental update technology is employed to update the core tensor and factor matrix,ensuring that the clustering model can adapt to changes in data.Finally,by combining the updated core tensor and factor matrix with historical computational results,refined clustering results are obtained,achieving real-time adaptation to dynamic data.Through experimental simulation on the Aminer dataset,the BDTMCDIncreUpdate method has demonstrated outstanding performance in terms of accuracy(ACC)and normalized mutual information(NMI)metrics,achieving an accuracy rate of 90%and an NMI score of 0.85,which outperforms existing methods such as TClusInitUpdate and TKLClusUpdate in most scenarios.Therefore,the BDTMCDIncreUpdate method offers an innovative solution to the field of big data analysis,integrating distributed computing,incremental updates,and tensor-based multi-clustering techniques.It not only improves the efficiency and scalability in processing large-scale high-dimensional datasets but also has been validated for its effectiveness and accuracy through experiments.This method shows great potential in real-world applications where dynamic data growth is common,and it is of significant importance for advancing the development of data an
基金The National Key Research and Development Project of China(No.2018YFB1600304)the National Natural Science Foundation of China(No.51878167,51678146)the National Natural Science Foundation of Xizang,China(No.XZ2018ZRG-10)。
文摘To investigate the environmental impacts of steel deck pavement through the whole life cycle,the steel deck pavement was divided into five stages:raw materials production,asphalt mixture mixing,pavement construction,operation management,and pavement removing stage.Based on the process-based life cycle assessment(PLCA)method,the calculation methods of energy consumption and gas emissions of two typical steel deck pavement systems(EA+EA pavement and GA+SMA pavement)were determined.The data lists of two pavements were analyzed,and the calculation model was built.Four characteristic indices including primary energy demand(PED),global warming potential(GWP),acidification potential(AP)and respiratory inorganics(RI)were used to quantify the environmental impacts of two pavements.The results show that the environmental impact of the GA+SMA pavement is more than 1.3 times that of the EA+EA pavement.Moreover,the critical stage of energy-saving and emission-reduction of EA+EA pavement and GA+SMA pavement are the raw material production stage and asphalt mixture mixing stage,respectively.
基金supported in part by the National Key Research and Development Program of China(Project No.2018YFB1600900)the Jiangsu Province Transportation Key Project of Science(Project No.2019Z01)Zhejiang Provincial Natural Science Foundation of China(No.LTGG23E080005).
文摘Short-term prediction of on-street parking occupancy is essential to the ITS system,which can guide drivers in finding vacant parking spaces.And the spatial dependencies and exogenous dependencies need to be considered simultaneously,which makes short-term prediction of on-street parking occupancy challenging.Therefore,this paper proposes a deep learning model for predicting block-level parking occupancy.First,the importance of multiple points of interest(POI)in different buffers is sorted by Boruta,used for feature selection.The results show that different types of POI data should consider different buffer radii.Then based on the real on-street parking data,long short-term memory(LSTM)that can address the time dependencies is applied to predict the parking occupancy.The results demonstrate that LSTM considering POI data after Boruta selection(LSTM(+BORUTA))outperforms other baseline methods,including LSTM,with an average testing MAPE of 11.78%.The selection process of POI data helps LSTM reduce training time and slightly improve the prediction performance,which indicates that complex correlations among the same type of POI data in different buffer zones will also affect the prediction accuracy of LSTM.When there are more restaurants on both sides of the street,the prediction performance of LSTM(+BORUTA)is significantly better than that of LSTM.
基金This work was supported in part by the National Natural Science Foundation of China(61872216,81630103,31900862,31725014)Jiangsu Provincial Emergency Project on Prevention and Control of COVID-19 Epidemic(BE2020601)+2 种基金the Nation Science and Technology Major Projects for Major New Drugs Innovation and Development(2018ZX09711003-004-002,2019ZX09301010)Pudong New Area Science and Technology Development Foundation(PKX2019-S08)the Turing Al Institute of Nanjing,and the Zhongguancun Haihua Institute for Frontier Information Technology.
文摘The global spread of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)requires an urgent need to find effective therapeutics for the treatment of coronavirus disease 2019(COVID-19).In this study,we developed an integrative drug repositioning framework,which fully takes advantage of machine learning and statistical analysis approaches to systematically integrate and mine large-scale knowledge graph,literature and transcriptome data to discover the potential drug candidates against SARS-CoV-2.Our in silico screening followed by wet-lab validation indicated that a poly-ADP-ribose polymerase 1(PARP1)inhibitor,CVL218,currently in Phase I clinical trial,may be repurposed to treat COVID-19.Our in vitro assays revealed that CVL218 can exhibit effective inhibitory activity against SARS-CoV-2 replication without obvious cytopathic effect.In addition,we showed that CVL218 can interact with the nucleocapsid(N)protein of SARS-CoV-2 and is able to suppress the LPS-induced production of several inflammatory cytokines that are highly relevant to the prevention of immunopathology induced by SARS-CoV-2 infection.
基金supported by the Fund for International Cooperation and Exchange of National Natural Science Foundation of China(61761136007)the National Key Research and Development Program of China(2017YFA0700201,2017YFA0700202,and 2017YFA0700203)+3 种基金the National Natural Science Foundation of China(6217010363,61631007,61571117,61501112,61501117,61871109,61522106,61731010,61735010,61722106,61701107,and 61701108)the Natural Science Foundation of Jiangsu Province(BK20211161)the 111 Project(111-2-05)ZhiShan Young Scholar Program of Southeast University.
文摘In current wireless communication and electronic systems,digital signals and electromagnetic(EM)radiation are processed by different modules.Here,we propose a mechanism to fuse the modulation of digital signals and the manipulation of EM radiation on a single programmable metasurface(PM).The PM consists of massive subwavelength-scale digital coding elements.A set of digital states of all elements forms simultaneous digital information roles for modulation and the wave-control sequence code of the PM.By designing digital coding sequences in the spatial and temporal domains,the digital information and farfield patterns of the PM can be programmed simultaneously and instantly in desired ways.For the experimental demonstration of the mechanism,we present a programmable wireless communication system.The same system can realize transmissions of digital information in single-channel modes with beamsteerable capability and multichannel modes with multiple independent information.The measured results show the excellent performance of the programmable system.This work provides excellent prospects for applications in fifth-or sixth-generation wireless communications and modern intelligent platforms for unmanned aircrafts and vehicles.
基金supported by the National Basic Research Program of China (2011CB302903)the National Natural Science Foundation of China (61201161, 61271335)the Postdoctoral Science Foundation of Jiangsu Province (1301002B)
文摘In order to take advantage of the asynchronous sensing information, alleviate the sensing overhead of secondary users （SUs） and improve the detection performance, a sensor node-assisted asynchronous cooperative spectrum sensing （SN-ACSS） scheme for cognitive radio （CR） network （CRN） was proposed. In SN-ACSS, each SU is surrounded by sensor nodes （SNs）, which asynchronously make hard decisions and soft decisions based on the Bayesian fusion rule instead of the SU. The SU combines these soft decisions and makes the local soft decision. Finally, the fusion center （FC） fuses the local soft decisions transmitted from SUs with different weight coefficients to attain the final soft decision. Besides, the impact of the statistics of licensed band occupancy on detection performance and the fact that different SNs have different sensing contributions are also considered in SN-ACSS scheme. Numerical results show that compared with the conventional synchronous cooperative spectrum sensing （SCSS） and the existing ACSS schemes, SN-ACSS algorithm achieves a better detection performance and lower cost with the same number of SNs.
文摘Flexible energy devices are the building blocks for next-generation wearable electronics.Flexible energy devices are expected to have multiple functions,such as energy conversion from light to electricity and vice versa,energy generation from triboelectric,energy storage and so on.These functions can be efficiently realized by solar cells,light-emitting diodes(LEDs),triboelectric nanogenerators(TENG),batteries and supercapacitors,etc.The flexible energy devices can be integrated into flexible,wearable,and/or portable platforms to enable wide application prospects in the fields of information,energy,medical care,national defense,etc.However,flexible energy devices face more challenges when compared to their rigid counterparts,which requires more breakthroughs and research efforts on fabrication techniques,materials innovation,novel structure designs,and deep physical understandings.
基金Funded by the National Natural Science Foundation of China (No 50901042)the NUST Research Funding(No.2011YBXM156)
文摘Magnesium alloy Mg-3%Al-1%Zn （AZ31） billets prepared from equal channel angular pressing （ECAP） were utilized in low-cycle fatigue tests in order to investigate their fatigue life. Fully reversed strain-controlled tension-compression fatigue tests were conducted at the frequency of 1 Hz in ambient air. The microstructures were examined by optical microscopy （OM） and scanning electron microscopy （SEM）. The hysteresis loops of the ECAP processed and conventionally extruded samples display obviously different shapes in the total strain amplitude range from 0.2% to 0.6%. Accordingly, the low cycle fatigue lives of ECAP processed samples are found to be longer than those of extruded samples, which can be attributed to the different in the hysteresis energy incorporating tensile strain energy.
基金This work was supported by Funding of Jiangsu Innovation Program for Graduate Education KYLX_0285,the National Natural Science Foundation of China(No.61602241)the Natural Science Foundation of Jiangsu Province(No.BK20150758)the pre-study fund of PLA University of Science and Technology.
文摘In the era of big data,the conflict between data mining and data privacy protection is increasing day by day.Traditional information security focuses on protecting the security of attribute values without semantic association.The data privacy of big data is mainly reflected in the effective use of data without exposing the user’s sensitive information.Considering the semantic association,reasonable security access for privacy protect is required.Semi-structured and self-descriptive XML(eXtensible Markup Language)has become a common form of data organization for database management in big data environments.Based on the semantic integration nature of XML data,this paper proposes a data access control model for individual users.Through the semantic dependency between data and the integration process from bottom to top,the global visual range of inverted XML structure is realized.Experimental results show that the model effectively protects the privacy and has high access efficiency.
文摘In 2020,the world has faced unprecedented challenges in human history with the Covid-19 pandemic,but communication systems and technologies have helped tremendously for teleworking and teleconferences.The progress of new technologies,particularly for satellite communication systems and applications,is facilitating the global coverage.
文摘By comparing Love Actually and Pretty Woman,the two representatives of romance comedy,it is not difficult to arrive at the conclusion that UK romance comedy is more realism while the other is more idealism.It more or less has something related to the different cultures and national characters between the US and the UK.
文摘The Adventure of Huckleberry Finn,one of Mark Twain’s masterpieces,is a story about a little child who pursues freedom together with his friend;however,if readers take it as easy as a fairy tale they will not really understand it.When exploring it deeply it is noticed that the book reveals profound social problems and interpersonal relationships.
文摘Multimedia teaching managemem system based on SIP ＆ P2P is proposed on account of the existing deficiency on video teaching of distance education. The designed P2P-SIP system applies SIP protocol to realize the underlying DHT, which guarantees zero-configuration, robustness and adaptability in P2P system. And maximum improvement in performance of the networks for multimedia system can be implemented by rapid networking and information sharing technology of the underlying P2P networks as well as fast call and location technology of SIP system. Experiments indicates that multimedia teaching management system based on SIP ＆ P2P could meet the requirement of system design on data latency and calling location.
