查看更多>>摘要：Multiple recursive generators with constant,as the high-order extension of linear congruence generators,form an important class of pseudorandom number generators that are widely used in cryptography.The predictabili-ty of truncated sequences output by multiple recursive generators with constant that predicts the whole sequences by the truncated high-order bits of the sequences,is a crucial problem in cryptography.This paper studies the predict-ability of truncated multiple recursive generators with constant.Given a few truncated digits of high-order bits output by a multiple recursive generator with constant,we first convert the multiple recursive generator with constant to multiple recursive generator and then adopt the method we proposed recently to recover the modulus,the coefficients,and the differences of initial state.In particular,we give an estimation of the number of truncated digits required for recovering the differences of initial state by using the expected norm of target vector.We prove by exponential sums that the number of truncated digits required for uniquely determining both the initial state and the constant is finite and give an upper bound.Extensive experiments confirm the correctness of our method.
查看更多>>摘要：A wideband circularly polarized(CP)aperture-coupled metasurface antenna operating at millimeter-wave frequency spectrum in substrate-integrated waveguide(SIW)technology is proposed.The proposed metasurface antenna is composed of two substrates.The first substrate contains an end-shorted SIW section with a slot etched.The introduced metasurface is printed on the top of the second substrate.The metasurface is comprised of 3 x 3 unit cells,each of which contains two interconnected patches and two parasitic patches.The working mechanism of the proposed metasurface antenna is illustrated in details.The proposed metasurface antenna has wide impedance band-width and axial ratio(AR)bandwidth,which are 66.7％and 40％,respectively.Using the proposed metasurface an-tenna,a 4 × 4 CP metasurface antenna array with an impedance bandwidth of 24％,an AR bandwidth of 30％,and a peak gain of 18.7 dBic in simulation is developed in this paper for millimeter-wave applications.
查看更多>>摘要：A novel design approach to wideband,dual-mode resonant monopole antenna with stable,enhanced backfire gain is advanced.The sectorial monopole evolves from a linear,0.75-wavelength electric prototype monopole under wideband dual-mode resonant operation.As theoretically predicted by the two resonant modes TE3/5,1 and TE9/5,1 within a 150° radiator,the operation principle is revealed at first.As have been numerically demonstrated and experimentally validated at 2.4-GHz band,the designed antenna exhibits a wide impedance bandwidth over 90.1％(i.e.,2.06-5.44 GHz),in which the stable gain bandwidth in the backfire,-x-direction(θ=90°,φ=180°)with peak value of 3.2 dBi and fluctuation less than 3 dB is up to 45.3％(i.e.,3.74-5.44 GHz).It is concluded that the stable wideband backfire gain frequency response should be owing to the high-order resonant mode in the unique sectorial monopole antennas.
查看更多>>摘要：A traveling-wave,extended interaction amplifier is herein investigated for use in millimeter-wave and terahertz amplification sources.By placing engineered extended interaction cavities between the traveling wave struc-tures,higher gain is obtained with a shorter high frequency circuit,compared with conventional traveling wave tubes architectures.The bandwidth of the device is significantly increased relative to extended interaction klystrons.A D-band beam wave interaction circuit of 26 mm long has been designed.Particle-in-cell simulations at 21.5-kV operating voltage,0.3-A beam current,and 5-mW input power show that the maximum output power reaches 351 W,with a gain of 48.4 dB and 3-dB bandwidth of 1.42 GHz.
查看更多>>摘要：In this paper,by introducing the spatial modulation(SM)scheme into the unmanned aerial vehicle(UAV)relaying system,an SM-aided UAV(SM-UAV)cooperative relay network is presented.The performance of the SM-UAV relay network is investigated over Nakagami-m fading channels,where the UAV remains stationary over a given area.According to the performance analysis,using the amplify-and-forward(AF)protocol,the effective signal-to-noise ratio(SNR)and the corresponding probability density function and moment generating function are,respectively,derived.With these results,the average bit error rate(BER)is further deduced,and resultant approxi-mate closed-form expression is achieved.Based on the approximate BER,we derive the asymptotic BER to charac-terize the error performance of the system at high SNR.With this asymptotic BER,the diversity gain of the system is derived,and the resulting diversity order is attained.Simulation results illustrate the effectiveness of the perform-ance analysis.Namely,approximate BER has the value close to the simulated one,and asymptotic BER can match the corresponding simulation well at high SNR.Thus,the BER performance of the system can be effectively assessed in theory,and conventional simulation will be avoided.Besides,the impacts of the antenna number,modulation order,fading parameter,and UAV position on the system performance are also analyzed.The results indicate that the BER performance is increased with the increases of Nakagami parameter m and/or receive antenna and/or the decrease of modulation order.
查看更多>>摘要：Unmanned aerial vehicle(UAV)-assisted mobile edge computing(MEC),as a way of coping with delay-sensitive and computing-intensive tasks,is considered to be a key technology to solving the challenges of terrestrial MEC networks.In this work,we study the problem of collaborative service provisioning(CSP)for UAV-assisted MEC.Specifically,taking into account the task latency and other resource constraints,this paper investigates how to minimize the total energy consumption of all terrestrial user equipments,by jointly optimizing computing resource al-location,task offloading,UAV trajectory,and service placement.The CSP problem is a non-convex mixed integer nonlinear programming problem,owing to the complex coupling of mixed integral variables and non-convexity of CSP.To address the CSP problem,this paper proposes an alternating optimization-based solution with the conver-gence guarantee as follows.We iteratively deal with the joint service placement and task offloading subproblem,and UAV movement trajectory subproblem,by branch and bound and successive convex approximation,respectively,while the closed form of the optimal computation resource allocation can be efficiently obtained.Extensive simula-tions validate the effectiveness of the proposed algorithm compared to three baselines.
查看更多>>摘要：This paper proposes a Markov decision process based service migration algorithm to satisfy quality of service(QoS)requirements when the terminals leave the original server.Services were divided into real-time services and non-real-time services,each type of them has different requirements on transmission bandwidth and latency,which were considered in the revenue function.Different values were assigned to the weight coefficients of QoS par-ameters for different service types in the revenue and cost functions so as to distinguish the differences between the two service types.The overall revenue was used for migration decisions,rather than fixed threshold or instant revenue.The Markov decision process was used to maximize the overall revenue of the system.Simulation results show that the proposed algorithm obtained more revenue compared with the existing works.
查看更多>>摘要：CircRNA-disease association(CDA)can provide a new direction for the treatment of diseases.However,traditional biological experiment is time-consuming and expensive,this urges us to propose the reliable computational model to predict the associations between circRNAs and diseases.And there is existing more and more evidence indi-cates that the combination of multi-biomolecular information can improve the prediction accuracy.We propose a novel computational model for CDA prediction named MBCDA,we collect the multi-biomolecular information in-cluding circRNA,disease,miRNA and lncRNA based on 6 databases,and construct three heterogeneous network among them,then the multi-heads graph attention networks are applied to these three networks to extract the fea-tures of circRNAs and diseases from different views,the obtained features are put into variational graph auto-encoder(VGAE)network to learn the latent distributions of the nodes,a fully connected neural network is adopted to further process the output of VGAE and uses sigmoid function to obtain the predicted probabilities of circRNA-disease pairs.As a result,MBCDA achieved the values of AUC and AUPR under 5-fold cross-validation of 0.893 and 0.887.MBCDA was applied to the analysis of the top-25 predicted associations between circRNAs and diseases,these experimental results show that our proposed MBCDA is a powerful computational model for CDA prediction.
查看更多>>摘要：The slow development of traditional computing has prompted the search for new materials to replace silicon-based computers.Bio-computers,which use molecules as the basis of computation,are highly parallel and in-formation capable,attracting a lot of attention.In this study,we designed a NAND logic gate based on the DNA strand displacement mechanism.We assembled a molecular calculation model,a 4-wire-2-wire priority encoder logic circuit,by cascading the proposed NAND gates.Different concentrations of input DNA chains were added into the system,resulting in corresponding output,through DNA hybridization and strand displacement.Therefore,it achieved the function of a priority encoder.Simulation results verify the effectiveness and accuracy of the molecular NAND logic gate and the priority coding system presented in this study.The unique point of this proposed circuit is that we cascaded only one kind of logic gate,which provides a beneficial exploration for the subsequent development of complex DNA cascade circuits and the realization of the logical coding function of information.
查看更多>>摘要：With the rapid development of railway transportation,virtual coupling(VC)has become a popular research topic.VC can greatly reduce tracking distance and increase the line capacity.Under VC control,the train formation control not only considers the behavior and speed adjustment strategy of the leader train but also the com-munication delays between trains.The quality of data communication between trains is an important aspect of train tracking control.We consider a virtually coupled train set(VCTS)as a multi-agent system.The Luenberger observ-er is introduced to estimate the real-time state of the train,based on the estimation,the train control consistency protocol is designed to account for communication delays.The stability of the error system is proven by constructing a Lyapunov function.The consistency of the coordinated train control is verified through simulation.
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