Electromagnetic scattering and imaging simulation of extremely large-scale sea-ship scene based on GPU parallel technology

Aiming to solve the bottleneck problem of electromagnetic scattering simulation in the scenes of extremely large-scale seas and ships,a high-frequency method by using graphics processing unit(GPU)parallel acceleration technique is proposed.For the implementation of different electromagnetic methods of physical optics(PO),shooting and bouncing ray(SBR),and physical theory of diffraction(PTD),a parallel computing scheme based on the CPU-GPU parallel computing scheme is realized to balance computing tasks.Finally,a multi-GPU framework is further proposed to solve the computational difficulty caused by the massive number of ray tubes in the ray tracing process.By using the established simulation platform,signals of ships at different seas are simulated and their images are achieved as well.It is shown that the higher sea states degrade the averaged peak signal-to-noise ratio(PSNR)of radar image.

Design of a Metasurface Antenna Based on Characteristic Mode Theory

A novel metasurface antenna consisting of 5×5 rectangular patch elements is presented.Thestructure with and without the central element are both analyzed by the Characteristic Mode Theory(CMT).The developed mutually orthogonal principal modes of the optimized periodic patch structure areexcited by a center-feed dipole.A differential feeding network is employed to realize impedance matching.Prototype with profile height of 0.07λ_(0)(λ_(0)is the wavelength in free space at the lowest operatingfrequency)is fabricated and assembled to verify the simulation results.The measured results show that thereflectance coefficient of proposed matesurface antenna is less than-10 dB in the whole operating bandrange from 4.2 GHz to 5.5 GHz,a relative bandwidth of 26.8%is achieved,and the maximummeasured realized gain is more than 9 dBi with a maximum radiation efficiency of 90%.The designprovides a guideline on the application of characteristic modes(CMs)to radiation problems.

Low profile cavity-embedded ultra-wideband UHF array antenna with end-fire beams

A low-profile,vertically polarized,ultra-wideband array antenna with end-fire beams operating in an ultra-high frequency(UHF)band is developed in this paper.The array antenna consists of 1×16 log-periodic top-hat loaded monopole antenna arrays and is feasible to embed into a shallow cavity to further reduce the array height.Capacitance is introduced in the proposed antenna element to reduce profile height and the rectangular top hats are carefully designed to minimize the transverse dimension.Simulated results show that when the antenna array operates in a frequency range of 300 MHz-900 MHz,the end-fire radiation pattern achieves±45°scanning range in the horizontal plane.Then prototypes of the proposed end-fire antenna element and a uniformly spaced linear array(1×2)are fabricated and validated.The end-fire antenna array should be suitable for airborne applications where low-profile and conformal scanning phased antenna arrays with end-fire radiations are required.This design is attractive for airborne platform applications that are used to search,discover,identify,and scout the aerial target with vertically polarized beams.

Ka-Band CTDRSS Terminal Technology for Meeting the Needs of Launch Vehicle TT&C

To meet the application requirements for a Ka-band space-based TT&C terminal for a launch vehicle,this paper proposes the implementation scheme of a space-based TT&C terminal,analyzes and solves the miniaturized design of equipment and the key technology for high-efficiency heat dissipation.The phased array antenna test shows that without external heat dissipation measures,the phased array antenna can work for a long time to meet the working requirements of launch vehicle,which has been verified in the LM-8 mission,and has wide engineering application prospects.

A Practical Regular LDPC Coded Scheme for Physical-Layer Information Security

In this paper,we aim to design a practical low complexity low-density parity-check(LDPC)coded scheme to build a secure open channel and protect information from eavesdropping.To this end,we first propose a punctured LDPC coded scheme,where the information bits in a codeword are punctured and only the parity check bits are transmitted to the receiver.We further propose a notion of check node type distribution and derive multi-edge type extrinsic information transfer functions to estimate the security performance,instead of the well-known weak metric bit error rate.We optimize the check node type distribution in terms of the signal-to-noise ratio(SNR)gap and modify the progressive edge growth algorithm to design finite-length codes.Numerical results show that our proposed scheme can achieve a lower computational complexity and a smaller security gap,compared to the existing scrambling and puncturing schemes.

Pattern Synthesis and Polarization Optimization of a Conical Array

A feasible method for synthesizing millimeter-wave conical array and optimizing low cross-polarization is proposed.Starting from the far-field superposition principle,an efficient approach including element mutual coupling and mounted platform effects is used to calculate the far-field patterns.A coordinate transform is applied to create polarization quantities,and a general process for the element polarized pattern transformation is performed.Corresponding numerical example is given and the desired sidelobe level and low cross-polarization are optimized.The numerical results indicate the proposed method is valid.

Research of Tile Type Transceiver Module Integrating with Two-Dimensional Sum Difference Network

Transceiver module and two-dimensional sum difference network are important components of phased array antenna. In this paper, multilayer printed board is used to integrate millimeter wave multi-channel transceiver circuit and sum difference network. The interconnection between them is realized through RF coaxial vertical transition. At the same time, the heat dissipation design and inter channel shielding design of the module are carried out. The RF and low frequency required by the module are completed through the wiring between and within the dielectric plate layers. Finally, 128 arrays are fabricated and verified by multi-channel passive test. The results show that the type transceiver module integrating with two-dimensional sum difference network has good performance, and 128 channels have excellent amplitude and phase characteristics. The integration technology has the characteristics of lightweight, miniaturization, high integration and low manufacturing cost. It can be widely used in miniaturized phased array antennas.

Semi-Supervised Clustering Algorithm Based on Deep Feature Mapping

Clustering analysis is one of the main concerns in data mining.A common approach to the clustering process is to bring together points that are close to each other and separate points that are away from each other.Therefore,measuring the distance between sample points is crucial to the effectiveness of clustering.Filtering features by label information and mea-suring the distance between samples by these features is a common supervised learning method to reconstruct distance metric.However,in many application scenarios,it is very expensive to obtain a large number of labeled samples.In this paper,to solve the clustering problem in the few supervised sample and high data dimensionality scenarios,a novel semi-supervised clustering algorithm is proposed by designing an improved prototype network that attempts to reconstruct the distance metric in the sample space with a small amount of pairwise supervised information,such as Must-Link and Cannot-Link,and then cluster the data in the new metric space.The core idea is to make the similar ones closer and the dissimilar ones further away through embedding mapping.Extensive experiments on both real-world and synthetic datasets show the effectiveness of this algorithm.Average clustering metrics on various datasets improved by 8%compared to the comparison algorithm.

A 285 GHz Tripler Using Planar Schottky Diode

In this paper, we present the design of a 285 GHz tripler realized by planar Schottky diode. The complete multiplying circuit and diodes is mounted on 50 um thick quartz substrate. The measured result shows that output power is achieved above 3.1 dBm in the range from 280 GHz to 290 GHz with a constantly 20 dBm driven power across the band. The peak power is 4 dBm in 285.6 GHz. .

A Miniaturized Broadband Wilkinson Power Divider Using Micro-Strip Branch Lines

A miniaturized broadband Wilkinson power divider is proposed. Micro-strip branch lines are introduced to replace multiple resistors used in multi-stage Wilkinson power dividers to increase the bandwidth of single-stage Wilkinson power dividers. To demonstrate its performance, an improved single-stage Wilkinson power divider with four micro-strip branch lines was designed. Simulated results show that the insert loss is better than 3.2 dB, the input return loss, output return loss, and isolation are better than 15 dB respectively, across a 76% bandwidth from 18 to 40 GHz. .

Timeliness optimization of unmanned aerial vehicle lossy communications for internet-of-things

Information freshness is a key factor for Internet-of-Things(IoT)to make appropriate decisions and operations.This paper proposes an analytical framework for evaluating the timeliness performance of the IoT system based on Unmanned Aerial Vehicle(UAV)lossy communications.The performance analysis consists of the outage probability analysis and the Age-of-Information(AoI)analysis with outages.To begin with,we solve a lossy coding problem formulated from the UAV communication system,and derive a closed-form expression of the outage probability based on Shannon's lossy source-channel separation theorem.Then,we characterize the Peak AoI(PAoI)for the considered system,and further minimize the PAoI by deriving the optimal rate for generating information.Moreover,we analyze the system performance through theoretical calculations and simulations.The results indicate that the optimal server utilization ratio is always no larger than 0.5.In practical applications,we can utilize the proposed analytical framework to determine the system parameters which guarantee the timeliness performance of UAV lossy communications.

INJECTION-LOCKED DIVIDER

An injection-Locked divider(ILD)can provide good synchronization at lower inputsignal to noise ratio,which is its advantage over other types of divider.The general expressionof phase equation and equivalent model are presented for the ILD with an input additive noise.In the absence of noise the performance of the phase-modulated signal through the ILD andsynchronous ranges of the ILD are given.The effects of the additive noise on the ILD arediscuued.The injection-locked amplifier(ILA)is only a particular case in which n=1,thereforethe given results arc applicable to the ILA.

Tile Type Multi-Channel Transceiver Module Applied for Phased Array Antenna

In order to reduce the volume and weight of phase array antenna in RF frequency, an integrated technology of multi-channel transceiver circuit and power division network in microwave is proposed for the tile type TR module. The component is integrated in a same dielectric substrate, the mounting interface of chips and power division network are on the same layer. Finally, a 8 × 8 array has been manufactured and tested to validate its function. The results show the integrated technology has good performance. It is very good to satisfy the miniaturization and lightweight of the T/R module in the active phased array antenna.

Blind reconnaissance of the pseudo-random sequence in DS/SS signal with negative SNR

This paper introduces a new theory and algorithm that can be used in blind detection of the carrier wave signal and the pseudo-random sequence of the direct sequence spread spectrum （DS/SS） signal with negative SNR. First, without any a priori knowledge of the DS/SS signal, the carrier wave signal can be detected from DS/SS signal with negative SNR by using stochastic differential equations and energy detection method. Based on this, the pseudo-random sequence can also be blindly detected in DS/SS signal with negative SNR by reducing noise of the nonlinear signal and the algorithm of wavelet multiscale decomposition algorithm. Finally, the computer simulation shows that we can detect the carrier wave signal with SNR=-27 dB and the pseudo-random sequence under error code ratio 10^-4with SNR =-10 dB.

A hybrid deep learning model for robust prediction of the dimensional accuracy in precision milling of thin-walled structural components

The use of artificial intelligence to process sensor data and predict the dimensional accuracy of machined parts is of great interest to the manufacturing community and can facilitate the intelligent production of many key engineering components.In this study,we develop a predictive model of the dimensional accuracy for precision milling of thin-walled structural components.The aim is to classify three typical features of a structural component—squares,slots,and holes—into various categories based on their dimensional errors(i.e.,“high precision,”“pass,”and“unqualified”).Two different types of classification schemes have been considered in this study:those that perform feature extraction by using the convolutional neural networks and those based on an explicit feature extraction procedure.The classification accuracy of the popular machine learning methods has been evaluated in comparison with the proposed deep learning model.Based on the experimental data collected during the milling experiments,the proposed model proved to be capable of predicting dimensional accuracy using cutting parameters(i.e.,“static features”)and cutting-force data(i.e.,“dynamic features”).The average classification accuracy obtained using the proposed deep learning model was 9.55%higher than the best machine learning algorithm considered in this paper.Moreover,the robustness of the hybrid model has been studied by considering the white Gaussian and coherent noises.Hence,the proposed hybrid model provides an efficient way of fusing different sources of process data and can be adopted for prediction of the machining quality in noisy environments.

IDL: Evaluating software quality based on PageRank algorithm

In the traditional method, the software quality is measured by various metrics of the software, such as decoupling level(DL), which can be used to predict software defect. However, DL, which treats all the files equally, has not taken file importance into consideration. Therefore, a novel software quality metric, named as improved decoupling level(IDL), based on the importance of documents was proposed. First, the PageRank algorithm was used to calculate the importance of files to obtain the weights of the dependencies, and then defect prediction models was established by combining the software scale, dependencies, scores and software defects to assess the software quality. Compared to most existing module-based software quality evaluation methods, IDL has similar or even superior performance in the prediction of software quality. The results indicate that IDL measures the importance of each file in the software more accurately by combining the PageRank algorithm in DL, which indirectly reflects the quality of software by predicting the bug information in software and improves the accuracy of prediction result of software bug information.

Waveform Design for Integrated Sensing and Communication Systems Based on Interference Exploitation

Integrated sensing and communication(ISAC)is a spectrum and energy efficient approach to realizing dual functions by a unified hardware platform.In this paper,we consider a multiple-input multiple-output(MIMO)ISAC system,where the transmitted waveform consisting of communication signals and dedicated sensing signal is optimized for dual purposes of estimating targets and serving downlink single-antenna users.Specifically,the sensing interference and multi-user interference are exploited,rather than suppressed,by the waveform design scheme.The joint waveform design problem is formulated by maximizing the constructive interference(CI)while ensuring the power budget and waveform similarity error with the benchmark signal,which limits the sensing estimation accuracy.To obtain the benchmark signal which achieves the optimal estimation performance,we propose a semidefinite relaxation based algorithm to solve the optimization problem.For clarity,we derive the real representation of the complex joint waveform design problem and prove its convexity.Numerical results verify the superiority of the proposed CI-based waveform design when the interference was efficiently exploited as a useful signal source achieving favorable symbol error ratio performance.Moreover,the dedicated sensing signal provides more degree of freedom for waveform design.

Twin-SSB signal reception without optical SSB filters based on self-coherent detection

Dater center interconnection has stimulated the development of short-reach optical communication transmission.To increase the capacity of the single sideband(SSB)system with direct-detection(DD),the twin-SSB system can double the system capacity without an extra optical modulator.Recently,the Stokes vector receiver(SVR)bridges the coherent detection and DD.A carrier can be sent along with the signal so that the SVR can utilize the reference carrier to conduct self-coherent detection and realize a linear complex optical detection,which is similar to the coherent receiver.In this paper,we propose a twin-SSB reception without optical SSB filters based on self-coherent detection.The proposed scheme greatly reduces the implementation complexity and has higher spectral efficiency(SE)compared with the traditional twin-SSB signal detection where two narrow-band optical filters and guard band are used for SSB signal extracting and inter crosstalk suppression.Meanwhile,the proposed twin-SSB signal detection with self-coherent detection also helps to relax the receiver digital signal processing(DSP),since the self-coherent detection reduces the inter crosstalk between the twin-SSB.The twin-SSB reception with self-coherent detection scheme makes it suitable for future high-speed short and medium-reach applications,such as the data center interconnect and metro area network.