Alginate-based magnetic micro/millirobots have demonstrated significant potential for biomedical applications due to their flexible structures and capacity to carry various types of cargo,such as cells,enabling target...Alginate-based magnetic micro/millirobots have demonstrated significant potential for biomedical applications due to their flexible structures and capacity to carry various types of cargo,such as cells,enabling targeted therapy to specific diseased regions within the body.Their active therapy is typically achieved through magnetic actuation and magnetic heating,while monitored by medical imaging methods like CT which pose additional risks due to radiation exposure.In the last decades,a novel imaging method for superparamagnetic materials,known as magnetic particle imaging(MPI),has been under active development,offering not only positional tracking but also the ability to measure concentration and temperature.Here,we report the world's first MPI-traceable magnetic hydrogel robots,which employ a combination of iron oxide nanoflowers,NdFeB powder,and calcium alginate.Unlike previous magnetic alginate robots composed of a single magnetic material,the synergistic combination of NdFeB and nanoflowers enables these robots to exhibit triple magnetic functionalities:magnetic heating,locomotion at low magnetic fields,and tracking,all of which can be controlled using a single all-in-one electromagnetic coil system.The effects of various magnetization fields,as well as different concentrations of NdFeB and nanoflowers on the robots'magnetic properties were analyzed.This led to the development of three types of triple-function robots(spiral,droplet,and hybrid),with experimental results demonstrating biocompatibility,a magnetic heating temperature increase of over 10℃in plasma fluid under a magnetic field of 13 kA·m^(-1)at 200 kHz,locomotion speeds of up to 25 mm·s^(-1)in fields below 2 mT,and an MPI tracking error of 2.8 mm with a selection field of 0.4 mT·mm^(-1).Additionally,the robots'capacity for localized thermal therapy and selectively targeted cell delivery,as well as their locomotion within a medical phantom against a maximum flow of 50 mm·s^(-1)were demonstrated.展开更多
As the 6th-Generation(6G)wireless communication networks evolve,privacy concerns are expected due to the transmission of vast amounts of security-sensitive private information.In this context,a Reconfigurable Intellig...As the 6th-Generation(6G)wireless communication networks evolve,privacy concerns are expected due to the transmission of vast amounts of security-sensitive private information.In this context,a Reconfigurable Intelligent Surface(RIS)emerges as a promising technology capable of enhancing transmission efficiency and strengthening information security.This study demonstrates how RISs can play a crucial role in making 6G networks more secure against eavesdropping attacks.We discuss the fundamentals and standardization aspects of RISs,along with an in-depth analysis of Physical-Layer Security(PLS).Our discussion centers on PLS design using RIS,highlighting aspects including beamforming,resource allocation,artificial noise,and cooperative communications.We also identify the research issues,propose potential solutions,and explore future perspectives.Finally,numerical results are provided to support our discussions and demonstrate the enhanced security enabled by RIS.展开更多
Recently,wireless security has been highlighted as one of the most important techniques for 6G mobile communication systems.Many researchers have tried to improve the Physical-Layer Security(PLS)performance such as Se...Recently,wireless security has been highlighted as one of the most important techniques for 6G mobile communication systems.Many researchers have tried to improve the Physical-Layer Security(PLS)performance such as Secrecy Outage Probability(SOP)and Secrecy Energy-Efficiency(SEE).The SOP indicates the outage probability that the data transmission between legitimate devices does not guarantee a certain reliability level,and the SEE is defined as the ratio between the achievable secrecy-rate and the consumed transmit power.In this paper,we consider a Multi-User Multi-Input Single-Output(MU-MISO)downlink cellular network where a legitimate Base Station(BS)equipped with multiple transmit antennas sends secure information to multiple legitimate Mobile Stations(MSs),and multiple potential eavesdroppers(EVEs)equipped with a single receive antenna try to eavesdrop on this information.Each potential EVE tries to intercept the secure information,i.e.,the private message,from the legitimate BS to legitimate MSs with a certain eavesdropping probability.To securely receive the private information,each legitimate MS feeds back its effective channel gain to the legitimate BS only when the effective channel gain is higher than a certain threshold,i.e.,the legitimate MSs adopt an Opportunistic Feedback(OF)strategy.In such eavesdropping channels,both SOP and SEE are analyzed as performance measures of PLS and their closed-form expressions are derived mathematically.Based on the analytical results,it is shown that the SOP of the OF strategy approaches that of a Full Feedback(FF)strategy as the number of legitimate MSs or the number of antennas at the BS increases.Furthermore,the trade-off between SOP and SEE as a function of the channel feedback threshold in the OF strategy is investigated.The analytical results and related observations are verified by numerical simulations.展开更多
Neural architecture search(NAS)optimizes neural network architectures to align with specific data and objectives,thereby enabling the design of high-performance models without specialized expertise.However,a significa...Neural architecture search(NAS)optimizes neural network architectures to align with specific data and objectives,thereby enabling the design of high-performance models without specialized expertise.However,a significant limitation of NAS is that it requires extensive computational resources and time.Consequently,performing a comprehensive architectural search for each new dataset is inefficient.Given the continuous expansion of available datasets,there is an urgent need to predict the optimal architecture for the previously unknown datasets.This study proposes a novel framework that generates architectures tailored to unknown datasets by mapping architectures that have demonstrated effectiveness on the existing dataset into a latent feature space.As NAS is inherently represented as graph structures,we employed an encoder-decoder transformation model based on variational graph auto-encoders to perform this latent feature mapping.The encoder-decoder transformation model demonstrates strong capability in extracting features from graph structures,making it particularly well-suited for mapping NAS architectures.By training variational graph auto-encoders on existing high-quality architectures,the proposed method constructs a latent space and facilitates the design of optimal architectures for diverse datasets.Furthermore,to effectively define similarity amongarchitectures,wepropose constructing the latent spaceby incorporatingbothdataset andtaskfeatures.Experimental results indicate that our approach significantly enhances search efficiency and outperforms conventional methods in terms of model performance.展开更多
C-axis oriented ZnO films are deposited on polished diamond substrates in various O2/(O2+Ar) ratios using the radio frequency(RF) magnetron sputtering technique and are subsequently annealed in oxygen ambience under t...C-axis oriented ZnO films are deposited on polished diamond substrates in various O2/(O2+Ar) ratios using the radio frequency(RF) magnetron sputtering technique and are subsequently annealed in oxygen ambience under the same conditions.Structural,morphologic and electrical properties of ZnO films are characterized by X-ray diffraction(XRD),high-resistance instrument,energy dispersive X-ray spectroscopy(EDS) and scanning electronic microscopy(SEM).As the O2/(O2+Ar) ratio increasing from 1/12 to 5/12,the crystallinity of the as grown ZnO films becomes better and the electrical resistivity increases slowly.After annealing,the ZnO films deposited in O2/(O2+Ar) =1/12 and 3/12 are improved greatly in crystallinity,and their electrical resistivity is enhanced by two orders of magnitude,while those deposited in O2/(O2+Ar) =5/12 are scarcely changed in crystallinity,and their resistivity is only increased by one order.In addition,the ZnO films deposited in O2/(O2+Ar) =3/12 and annealed in oxygen are with the best crystal quality and the highest resistivity.展开更多
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 quantitative effects of chromium content on continuous cooling transformation （CCT） diagrams of novel air-cooled bainite steels were analyzed using artificial neural network models. The results showed that the c...The quantitative effects of chromium content on continuous cooling transformation （CCT） diagrams of novel air-cooled bainite steels were analyzed using artificial neural network models. The results showed that the chromium may retard the high and medium-temperature martensite transformation.展开更多
RBF model,a new type of artificial neural network model was developed to design the content of carbon in low-alloy engineering steels.The errors of the ANN model are：MSE 0.052 1,MSRE 17.85%,and VOF 1.932 9.The result...RBF model,a new type of artificial neural network model was developed to design the content of carbon in low-alloy engineering steels.The errors of the ANN model are：MSE 0.052 1,MSRE 17.85%,and VOF 1.932 9.The results obtained are satisfactory.The method is a powerful aid for designing new steels.展开更多
In this paper,an ultraviolet C-band laser diode lasing at 277 nm composed of B0.313Ga0.687N/B0.40Ga0.60N QW/QB heterostructure on Mg and Si-doped AlxGa1-xN layers was designed,as well as a lowest reported substitution...In this paper,an ultraviolet C-band laser diode lasing at 277 nm composed of B0.313Ga0.687N/B0.40Ga0.60N QW/QB heterostructure on Mg and Si-doped AlxGa1-xN layers was designed,as well as a lowest reported substitutional accepter and donor concentration up to NA=5.0×10^17 cm^-3 and ND=9.0×10^16 cm^-3 for deep ultraviolet lasing was achieved.The structure was assumed to be grown over bulk AIN substrate and operate under a continuous wave at room temperature.Although there is an emphasizing of the suitability for using boron nitride wide band gap in the deep ultraviolet region,there is still a shortage of investigation about the ternary BGaN in aluminum-rich AIGaN alloys.Based on the simulation,an average local gain in quantum wells of 1946 cm^-1,the maximum emitted power of 2.4 W,the threshold current of 500 mA,a slope efficiency of 1.91 W/A as well as an average DC resistance for the V-I curve of(0.336Ω)had been observed.Along with an investigation regarding different EBL,designs were included with tapered and inverse tapered structure.Therefore,it had been found a good agreement with the published results for tapered EBL design,with an overweighting for a proposed inverse tapered EBL design.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
A rotational parameter Rθ has been introduced to complex wavelet transform （CWT）. The rotational CWT （RCWT） corresponds to a matrix element 〈φ｜U2（θ;μ;κ）[F〉 in the context of quantum mechanics, where U2（...A rotational parameter Rθ has been introduced to complex wavelet transform （CWT）. The rotational CWT （RCWT） corresponds to a matrix element 〈φ｜U2（θ;μ;κ）[F〉 in the context of quantum mechanics, where U2（θ;μ;κ） is a two-mode rotational displacing-squeezing operator in the 〈η｜ representation. Based on this, the Parseval theorem and the inversion formula of RCWT have been proved. The concise proof not only manifestly shows the merit of Dirac＇s representation theory but also leads to a new orthogonal property of complex mother wavelets in parameter space.展开更多
A wear-resistant material reinforced with VCp was manufactured by the in-mold melting process, in which the high-vanadium alloy-rods were melted by high temperature liquid steel and elements diffused into the liquid. ...A wear-resistant material reinforced with VCp was manufactured by the in-mold melting process, in which the high-vanadium alloy-rods were melted by high temperature liquid steel and elements diffused into the liquid. Microstructure of the material was examined by OM, SEM, and XRD, and alloy elements in the diffusion layer were studied by EDS, and the hardness of the material was tested by HRS. The experimental results show that the material gradually changes hardness, which is due to the uniformly existents of carbide particles on martensite matrix and the gradient distribution of vanadium and carbide.展开更多
A class of nonlinear differential-integral singular perturbation problem for the disturbed evolution equations is studied. Using the singular perturbation method, the structure of solution to problem is discussed in t...A class of nonlinear differential-integral singular perturbation problem for the disturbed evolution equations is studied. Using the singular perturbation method, the structure of solution to problem is discussed in the cases of two small parameters and under the suitable conditions. Firstly, the outer solution to boundary value problem is given. Secondly, constructing the non-singular coordinate system near the boundary, the variables of multiple scales is introduced to obtain the boundary layer corrective term for the solution. Then the stretched variable is applied to get the initial layer correction term. Finally, using the fix point theorem, the uniformly valid asymptotic expansion of the solution to problem is proved. The proposed method possesses the advantages of convenient use and high accuracy.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.
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 introduces an effective software-based FEC redundant packets generating algorithm. The algorithm is based on Reed-Solomon coding over Galois Field. By operating on words of packets and performing polynomial...This paper introduces an effective software-based FEC redundant packets generating algorithm. The algorithm is based on Reed-Solomon coding over Galois Field. By operating on words of packets and performing polynomial multiplication via lookup tables, software coding efficiency is achieved to satisfy the needs of most of computer network applications. The approach to generate lookup tables is detailed.展开更多
Catalyst-free graphene films has been synthesized by microwave (MW) surface wave plasma (SWP) chemical vapor deposition (CVD) using hydrogenated carbon source on silicon substrates at low temperature (500℃). The synt...Catalyst-free graphene films has been synthesized by microwave (MW) surface wave plasma (SWP) chemical vapor deposition (CVD) using hydrogenated carbon source on silicon substrates at low temperature (500℃). The synthesized process is simple, low-cost and possible for application on transparent electrodes, gas sensors and thin film resistors. Analytical methods such as Raman spectroscopy, transmission electron microscopy (TEM) and four points prove resistivity measurement and UV-VIS-NIR spectroscopy were employed to characterize properties of the graphene films. The formation of multilayer of graphene on silicon substrate was confirmed by Raman spectroscopy and TEM. It is possible to grow graphene directly on silicon substrate (without using catalyst) due to high radical density of MW SWP CVD. In addition, we also observed that the hydrogen had significant role for quality of graphene.展开更多
Amorphous carbon (a-C) thin films have been synthesized by microwave (MW) surface wave plasma (SWP) chemical vapor deposition (CVD) on n-type silicon and quartz substrates, aiming at the application of the films for p...Amorphous carbon (a-C) thin films have been synthesized by microwave (MW) surface wave plasma (SWP) chemical vapor deposition (CVD) on n-type silicon and quartz substrates, aiming at the application of the films for photovoltaic solar cells. Argon, acetylene and trimethylboron were used as a carrier, source and dopant gases. Analytical methods such as X-ray photoelectron spectroscopy (XPS), Hall Effect measurement, JASCO V-570 UV/VIS/NIR spectroscopy, Raman spectroscopy, Transmission electron microscopy (TEM) and Solar simulator were employed to investigate chemical, optical, structural and electrical properties of the a-C films. Two types of solar cells of configuration p-C/n-Si and p-C/i-C/n-Si have been fabricated and their current-voltage characteristics under dark and illumination (AM 1.5, 100 mW/cm2) have been studied. The two solar cells showed rectifying curves under the dark condition confirming the heterojunction carbon based solar cell between p-C and n-Si. When illuminated by the solar simulator light the devices showed photovoltaic behavior. The heterojunction device (p-C/i-C/n-Si) having inserted intrinsic carbon film between p-C and n-Si exhibited significant enhancement of the conversation efficiency (0.167% to 2.349%) over the device (p-C/n-Si).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
基金supported by a Korea University Grantby the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)with Grant Number 2022R1A2C1003381。
文摘Alginate-based magnetic micro/millirobots have demonstrated significant potential for biomedical applications due to their flexible structures and capacity to carry various types of cargo,such as cells,enabling targeted therapy to specific diseased regions within the body.Their active therapy is typically achieved through magnetic actuation and magnetic heating,while monitored by medical imaging methods like CT which pose additional risks due to radiation exposure.In the last decades,a novel imaging method for superparamagnetic materials,known as magnetic particle imaging(MPI),has been under active development,offering not only positional tracking but also the ability to measure concentration and temperature.Here,we report the world's first MPI-traceable magnetic hydrogel robots,which employ a combination of iron oxide nanoflowers,NdFeB powder,and calcium alginate.Unlike previous magnetic alginate robots composed of a single magnetic material,the synergistic combination of NdFeB and nanoflowers enables these robots to exhibit triple magnetic functionalities:magnetic heating,locomotion at low magnetic fields,and tracking,all of which can be controlled using a single all-in-one electromagnetic coil system.The effects of various magnetization fields,as well as different concentrations of NdFeB and nanoflowers on the robots'magnetic properties were analyzed.This led to the development of three types of triple-function robots(spiral,droplet,and hybrid),with experimental results demonstrating biocompatibility,a magnetic heating temperature increase of over 10℃in plasma fluid under a magnetic field of 13 kA·m^(-1)at 200 kHz,locomotion speeds of up to 25 mm·s^(-1)in fields below 2 mT,and an MPI tracking error of 2.8 mm with a selection field of 0.4 mT·mm^(-1).Additionally,the robots'capacity for localized thermal therapy and selectively targeted cell delivery,as well as their locomotion within a medical phantom against a maximum flow of 50 mm·s^(-1)were demonstrated.
基金supported by Institute of Information&communications Technology Planning&Evaluation(IITP)grant funded by the Korea government(MSIT)(No.2020-0-00045,Development of movable high-capacity mobile communication infrastructure for telecommunication disaster and rescue)IITP grant funded by the Korea government(MSIT)(No.2021-0-00972,Development of intelligent wireless access technology)。
文摘As the 6th-Generation(6G)wireless communication networks evolve,privacy concerns are expected due to the transmission of vast amounts of security-sensitive private information.In this context,a Reconfigurable Intelligent Surface(RIS)emerges as a promising technology capable of enhancing transmission efficiency and strengthening information security.This study demonstrates how RISs can play a crucial role in making 6G networks more secure against eavesdropping attacks.We discuss the fundamentals and standardization aspects of RISs,along with an in-depth analysis of Physical-Layer Security(PLS).Our discussion centers on PLS design using RIS,highlighting aspects including beamforming,resource allocation,artificial noise,and cooperative communications.We also identify the research issues,propose potential solutions,and explore future perspectives.Finally,numerical results are provided to support our discussions and demonstrate the enhanced security enabled by RIS.
基金supported in part by the National Research Foundation of Korea(NRF)funded by the Korea government(MSIT)under Grant NRF-2022R1I1A3073740in part by the Institute for Information and Communications Technology Promotion(IITP)Grant funded by the Korea Government(MSIP,Development of Cube Satellites Based on Core Technologies in Low Earth Orbit Satellite Communications)under Grant RS-2024-00396992in part by Institute of Information&communications Technology Planning&Evaluation(IITP)grant funded by the Korea government(MSIT)(2022-0-00704,Development of 3D-NET Core Technology for High-Mobility Vehicular Service)。
文摘Recently,wireless security has been highlighted as one of the most important techniques for 6G mobile communication systems.Many researchers have tried to improve the Physical-Layer Security(PLS)performance such as Secrecy Outage Probability(SOP)and Secrecy Energy-Efficiency(SEE).The SOP indicates the outage probability that the data transmission between legitimate devices does not guarantee a certain reliability level,and the SEE is defined as the ratio between the achievable secrecy-rate and the consumed transmit power.In this paper,we consider a Multi-User Multi-Input Single-Output(MU-MISO)downlink cellular network where a legitimate Base Station(BS)equipped with multiple transmit antennas sends secure information to multiple legitimate Mobile Stations(MSs),and multiple potential eavesdroppers(EVEs)equipped with a single receive antenna try to eavesdrop on this information.Each potential EVE tries to intercept the secure information,i.e.,the private message,from the legitimate BS to legitimate MSs with a certain eavesdropping probability.To securely receive the private information,each legitimate MS feeds back its effective channel gain to the legitimate BS only when the effective channel gain is higher than a certain threshold,i.e.,the legitimate MSs adopt an Opportunistic Feedback(OF)strategy.In such eavesdropping channels,both SOP and SEE are analyzed as performance measures of PLS and their closed-form expressions are derived mathematically.Based on the analytical results,it is shown that the SOP of the OF strategy approaches that of a Full Feedback(FF)strategy as the number of legitimate MSs or the number of antennas at the BS increases.Furthermore,the trade-off between SOP and SEE as a function of the channel feedback threshold in the OF strategy is investigated.The analytical results and related observations are verified by numerical simulations.
基金funded by the New Energy and Industrial Technology Development Organization(NEDO),grant number JPNP18002.
文摘Neural architecture search(NAS)optimizes neural network architectures to align with specific data and objectives,thereby enabling the design of high-performance models without specialized expertise.However,a significant limitation of NAS is that it requires extensive computational resources and time.Consequently,performing a comprehensive architectural search for each new dataset is inefficient.Given the continuous expansion of available datasets,there is an urgent need to predict the optimal architecture for the previously unknown datasets.This study proposes a novel framework that generates architectures tailored to unknown datasets by mapping architectures that have demonstrated effectiveness on the existing dataset into a latent feature space.As NAS is inherently represented as graph structures,we employed an encoder-decoder transformation model based on variational graph auto-encoders to perform this latent feature mapping.The encoder-decoder transformation model demonstrates strong capability in extracting features from graph structures,making it particularly well-suited for mapping NAS architectures.By training variational graph auto-encoders on existing high-quality architectures,the proposed method constructs a latent space and facilitates the design of optimal architectures for diverse datasets.Furthermore,to effectively define similarity amongarchitectures,wepropose constructing the latent spaceby incorporatingbothdataset andtaskfeatures.Experimental results indicate that our approach significantly enhances search efficiency and outperforms conventional methods in terms of model performance.
基金supported by the National Natural Science Foundation of China (No. 50972105)Tianjin Natural Science Foundation (No.09JCZDJC16500)
文摘C-axis oriented ZnO films are deposited on polished diamond substrates in various O2/(O2+Ar) ratios using the radio frequency(RF) magnetron sputtering technique and are subsequently annealed in oxygen ambience under the same conditions.Structural,morphologic and electrical properties of ZnO films are characterized by X-ray diffraction(XRD),high-resistance instrument,energy dispersive X-ray spectroscopy(EDS) and scanning electronic microscopy(SEM).As the O2/(O2+Ar) ratio increasing from 1/12 to 5/12,the crystallinity of the as grown ZnO films becomes better and the electrical resistivity increases slowly.After annealing,the ZnO films deposited in O2/(O2+Ar) =1/12 and 3/12 are improved greatly in crystallinity,and their electrical resistivity is enhanced by two orders of magnitude,while those deposited in O2/(O2+Ar) =5/12 are scarcely changed in crystallinity,and their resistivity is only increased by one order.In addition,the ZnO films deposited in O2/(O2+Ar) =3/12 and annealed in oxygen are with the best crystal quality and the highest resistivity.
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 quantitative effects of chromium content on continuous cooling transformation （CCT） diagrams of novel air-cooled bainite steels were analyzed using artificial neural network models. The results showed that the chromium may retard the high and medium-temperature martensite transformation.
文摘RBF model,a new type of artificial neural network model was developed to design the content of carbon in low-alloy engineering steels.The errors of the ANN model are：MSE 0.052 1,MSRE 17.85%,and VOF 1.932 9.The results obtained are satisfactory.The method is a powerful aid for designing new steels.
基金National Key Research and Development Program (Nos. NKRDP 2016YFE0118400)the Key project of Science and Technology of Henan Province (No. 172102410062)+1 种基金National Natural Science Foundation of China (No. 61176008)National Natural Science Foundation of China Henan Provincial Joint Fund Key Project (No. U1604263)
文摘In this paper,an ultraviolet C-band laser diode lasing at 277 nm composed of B0.313Ga0.687N/B0.40Ga0.60N QW/QB heterostructure on Mg and Si-doped AlxGa1-xN layers was designed,as well as a lowest reported substitutional accepter and donor concentration up to NA=5.0×10^17 cm^-3 and ND=9.0×10^16 cm^-3 for deep ultraviolet lasing was achieved.The structure was assumed to be grown over bulk AIN substrate and operate under a continuous wave at room temperature.Although there is an emphasizing of the suitability for using boron nitride wide band gap in the deep ultraviolet region,there is still a shortage of investigation about the ternary BGaN in aluminum-rich AIGaN alloys.Based on the simulation,an average local gain in quantum wells of 1946 cm^-1,the maximum emitted power of 2.4 W,the threshold current of 500 mA,a slope efficiency of 1.91 W/A as well as an average DC resistance for the V-I curve of(0.336Ω)had been observed.Along with an investigation regarding different EBL,designs were included with tapered and inverse tapered structure.Therefore,it had been found a good agreement with the published results for tapered EBL design,with an overweighting for a proposed inverse tapered EBL design.
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National Natural Science Foundation of China under Grant No.10647133the Research Foundation of the Education Department of Jiangxi Province under Grant No.[2007]22
文摘A rotational parameter Rθ has been introduced to complex wavelet transform （CWT）. The rotational CWT （RCWT） corresponds to a matrix element 〈φ｜U2（θ;μ;κ）[F〉 in the context of quantum mechanics, where U2（θ;μ;κ） is a two-mode rotational displacing-squeezing operator in the 〈η｜ representation. Based on this, the Parseval theorem and the inversion formula of RCWT have been proved. The concise proof not only manifestly shows the merit of Dirac＇s representation theory but also leads to a new orthogonal property of complex mother wavelets in parameter space.
基金Funded by the Natural Science Foundation of Guangdong Province (9151064201000052)the Innovation Research Foundation of Wuhan University of Technology(2010-ZY-CL-065)
文摘A wear-resistant material reinforced with VCp was manufactured by the in-mold melting process, in which the high-vanadium alloy-rods were melted by high temperature liquid steel and elements diffused into the liquid. Microstructure of the material was examined by OM, SEM, and XRD, and alloy elements in the diffusion layer were studied by EDS, and the hardness of the material was tested by HRS. The experimental results show that the material gradually changes hardness, which is due to the uniformly existents of carbide particles on martensite matrix and the gradient distribution of vanadium and carbide.
基金Supported by the National Natural Science Foundation of China(11202106)the Natural Science Foundation of the Education Department of Anhui Province(KJ2017A702)the Key Projects of Outstanding Young Talents of Universities in Anhui Province(gxyqZD2016520)
文摘A class of nonlinear differential-integral singular perturbation problem for the disturbed evolution equations is studied. Using the singular perturbation method, the structure of solution to problem is discussed in the cases of two small parameters and under the suitable conditions. Firstly, the outer solution to boundary value problem is given. Secondly, constructing the non-singular coordinate system near the boundary, the variables of multiple scales is introduced to obtain the boundary layer corrective term for the solution. Then the stretched variable is applied to get the initial layer correction term. Finally, using the fix point theorem, the uniformly valid asymptotic expansion of the solution to problem is proved. The proposed method possesses the advantages of convenient use and high accuracy.
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 introduces an effective software-based FEC redundant packets generating algorithm. The algorithm is based on Reed-Solomon coding over Galois Field. By operating on words of packets and performing polynomial multiplication via lookup tables, software coding efficiency is achieved to satisfy the needs of most of computer network applications. The approach to generate lookup tables is detailed.
文摘Catalyst-free graphene films has been synthesized by microwave (MW) surface wave plasma (SWP) chemical vapor deposition (CVD) using hydrogenated carbon source on silicon substrates at low temperature (500℃). The synthesized process is simple, low-cost and possible for application on transparent electrodes, gas sensors and thin film resistors. Analytical methods such as Raman spectroscopy, transmission electron microscopy (TEM) and four points prove resistivity measurement and UV-VIS-NIR spectroscopy were employed to characterize properties of the graphene films. The formation of multilayer of graphene on silicon substrate was confirmed by Raman spectroscopy and TEM. It is possible to grow graphene directly on silicon substrate (without using catalyst) due to high radical density of MW SWP CVD. In addition, we also observed that the hydrogen had significant role for quality of graphene.
文摘Amorphous carbon (a-C) thin films have been synthesized by microwave (MW) surface wave plasma (SWP) chemical vapor deposition (CVD) on n-type silicon and quartz substrates, aiming at the application of the films for photovoltaic solar cells. Argon, acetylene and trimethylboron were used as a carrier, source and dopant gases. Analytical methods such as X-ray photoelectron spectroscopy (XPS), Hall Effect measurement, JASCO V-570 UV/VIS/NIR spectroscopy, Raman spectroscopy, Transmission electron microscopy (TEM) and Solar simulator were employed to investigate chemical, optical, structural and electrical properties of the a-C films. Two types of solar cells of configuration p-C/n-Si and p-C/i-C/n-Si have been fabricated and their current-voltage characteristics under dark and illumination (AM 1.5, 100 mW/cm2) have been studied. The two solar cells showed rectifying curves under the dark condition confirming the heterojunction carbon based solar cell between p-C and n-Si. When illuminated by the solar simulator light the devices showed photovoltaic behavior. The heterojunction device (p-C/i-C/n-Si) having inserted intrinsic carbon film between p-C and n-Si exhibited significant enhancement of the conversation efficiency (0.167% to 2.349%) over the device (p-C/n-Si).
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.
