STATISTICAL SPACE-TIME ADAPTIVE PROCESSING ALGORITHM

For the slowly changed environment-range-dependent non-homogeneity, a new statistical space-time adaptive processing algorithm is proposed, which uses the statistical methods, such as Bayes or likelihood criterion to estimate the approximative covariance matrix in the non-homogeneous condition. According to the statistical characteristics of the space-time snapshot data, via defining the aggregate snapshot data and corresponding events, the conditional probability of the space-time snapshot data which is the effective training data is given, then the weighting coefficients are obtained for the weighting method. The theory analysis indicates that the statistical methods of the Bayes and likelihood criterion for covariance matrix estimation are more reasonable than other methods that estimate the covariance matrix with the use of training data except the detected outliers. The last simulations attest that the proposed algorithms can estimate the covariance in the non-homogeneous condition exactly and have favorable characteristics.

W ideband interference suppression based on space-time filter

Based upon the diagonal loading technique and the structure of the space-time adaptive processors,a novel anti-jamming method of satellite navigation is proposed. According to matrix inverse theorem,the range of the diagonal loading values for space-time adaptive wideband signal processing structure is deduced,and the optimum equation of diagonal loading beam forming algorithm of space-time structure is obtained. Then,by the analysis of two-dimensional oriented vector in direction of the perturbation interference,the wideband interference covariance matrix obtained in the weights training period is modified. Finally,the optimum weight of multi-linear constrained space-time adaptive beam-forming alogrithm is derived for anti-interference filter processing. The new method effectively widens the null steering beams when discrepancy happens. The computer simulation results prove the robustness of the proposed method.

IMPROVED DOPPLER WARPING METHOD FOR AIRBORNE RADAR WITH NON-SIDELOOKING ARRAY

Traditional range-dependency compensation space time adaptive processing(STAP)methods usually involve aligning the clutter spectrums in a certain point to reduce the clutter non-homogeneity.A novel compensation STAP method is proposed as an improved Doppler warping(DW)method for airborne radar with non-sidelooking radar.This method facilitates DW method to bring clutter spectrum of different range gates together in the mainlobe and subsequently compensation to accomplish space angle of different range gates alignment at multiple Doppler bins.Simulation results show that the proposed method can further reduce the clutter non-homogeneity of non-sidelooking array and significantly outperform traditional algorithms with only a little increase of the computation load.

STAP method based on atomic norm minimization with array amplitude-phase error calibration

In this paper,a space-time adaptive processing(STAP)method is proposed for the airborne radar with the array amplitude-phase error considered,which is based on atomic norm minimization(ANM).In the conventional ANM-based STAP method,the influence of the array amplitude-phase error is not considered and restrained,which inevitably causes performance deterioration.To solve this problem,the array amplitude-phase error is firstly estimated.Then,by pre-estimating the array amplitude-phase error information,a modified ANM model is built,in which the array amplitude-phase error factor is separated from the clutter response and the clutter covariance matrix(CCM)to improve the estimation accuracy of the CCM.To prove that the atomic norm theory is applicable in the presence of the array amplitude-phase error,the clutter sparsity is analyzed in this paper.Meanwhile,simulation results demonstrate that the proposed method is superior to the state-of-the-art STAP method.Moreover,the measured data is used to verify the effectiveness of the proposed method.

A NEW METHOD TO COMPENSATE CLUTTER RANGE DEPENDENCE FOR FORWARD LOOKING AIRBORNE RADARS

The clutter direction-Doppler curves are not aligned on the near range bins for forward looking airborne radar. As a result, the performance of clutter suppression by Space-Time Adaptive Processing (STAP) degrades greatly because of the clutter range dependence. To deal with this problem, a new compensated method is proposed in this paper. The method rebuilds the clutter covariance matrix based on spatial high resolution Minimum Variance Distortionless Response (MVDR) spectrum, and then finds a matrix to transform the covariance matrix of short-range gate to the referred far-range gate. The method can compensate the clutter range dependence well. The simulation results show validity of the method.

AN APPROACH TO SUPPRESS SHORT-RANGE CLUTTER FOR NON-SIDE LOOKING AIRBORNE RADAR

When the Airborne Early Warning(AEW) radar transmits medial or high Pulse Repetitive Frequency(PRF) signal,the range ambiguity occurs.The clutter of short-range clutter has serious range dependence problem for non-Side Looking Airborne Radar(non-SLAR).As a result,the clutter plus noise covariance matrix can not be estimated correctly,and the performance of clutter suppression obtained by Space-Time Adaptive Processing(STAP) degrades greatly.The uniform linear array has not elevation degrees;therefore,the short-range clutter can not be suppressed directly.A short-range clutter suppression method is proposed.The method first estimate the elevation angles of the ambiguous short-range gate,then eliminates short-range clutter by space time interpolation and adds moving target protection in the procedure.This method can suppress the short-range clutter well.Simulation results show the validity of the method.

Analysis of Moving Target Detection in Space-Surface BiSAR

Based on the geometric structure of multi-channel space-surface bistatic aperture radar(SS-BiSAR),the time-frequency and spatial-frequency relationships of clutter and moving target are detailedly analyzed.It is found that the prepositive stationary receiver can improve the spatial separation between moving target and correspondingly competitive clutter,furthermore the processing scheme of space-time adaptive processing(STAP) in SS-BiSAR echo domain is given.Meanwhile,compared to the STAP in monostatic synthetic aperture radar(SAR),it is firstly proved that the minimum detectable velocity in SS-BiSAR system can improve R0/R1(transmitter-to-target distance over receiver-to-target) times.Finally,the computer simulation verifies the effectiveness of the STAP processing scheme.

Micro Evolutionary Processes and Adaptation

It would be well to note that in the absence of clear data about the formation of adaptation systems,or mechanisms of their occurrence,all that is recognized is the realization of the micro evolutionary processes.There is no well-defined connection between information exchange and formation

Fuzzy Stochastic Differential Equations Driven by a Fuzzy Brownian Motion

In our previous work, we study fuzzy Itôintegrals driven by a fuzzy Brownian motion. In this article, we continue this study. The purpose of this paper is to study the weak uniqueness of fuzzy stochastic differential equations taking into account fuzzy Brownian motion. For instance, we construct the fuzzy stochastic differential equation driven by a fuzzy Brownian motion. To define and prove our results, we use the fuzzification, the alpha cut method and the Hausdorff distance between two fuzzy quantities. Some results are to our credit in this article like the instance, we construct the fuzzy stochastic differrential equation driven by fuzzy Brownian motion. Furthermore, we develop fuzzy Itôcalculus driven by a fuzzy Brownian motion. Our result complement existing ones in that the fuzzy version of Brownian motion is taken into account.

Enhanced performance of triboelectric mechanical motion sensor via continuous charge supplement and adaptive signal processing

The development of automation industry is inseparable from the progress of sensing technology.As a promising self-powered sensing technology,the durability and stability of triboelectric sensor(TES)have always been inevitable challenges.Herein,a continuous charge supplement(CCS)strategy and an adaptive signal processing(ASP)method are proposed to improve the lifetime and robustness of TES.The CCS uses low friction brushes to increase the surface charge density of the dielectric,ensuring the reliability of sensing.A triboelectric mechanical motion sensor(TMMS)with CCS is designed,and its electrical signal is hardly attenuated after 1.5 million cycles after reasonable parameter optimization,which is unprecedented in linear TESs.After that,the dynamic characteristics of the CCS-TMMS are analyzed with error rates of less than 1%and 2%for displacement and velocity,respectively,and a signal-to-noise ratio of more than 35 dB.Also,the ASP used a signal conditioning circuit for impedance matching and analog-to-digital conversion to achieve a stable output of digital signals,while the integrated design and manufacture of each hardware module is achieved.Finally,an intelligent logistics transmission system(ILTS)capable of wirelessly monitoring multiple motion parameters is developed.This work is expected to contribute to automation industries such as smart factories and unmanned warehousing.

Machining fixture for adaptive CNC machining process of near-net-shaped jet engine blade

Low stiffness and positioning problems are difficulties and challenges in the precise machining of near-net-shaped blades.This paper aims to achieve high accuracy in manufacturing by fixture-and deformation-control in the adaptive CNC machining process.Adaptive CNC machining technology is first analyzed,and new fixture-evaluation criteria and methods to evaluate the adaptive CNC machining process fixture design are built.Second,a machining fixture is designed and manufactured after analyzing its positioning scheme,clamping scheme,materials(PEEK-GF30),and structure characteristics.Finally,the designed fixture is analyzed by FEA and experimentally verified by a cutting experiment.The results show that the deformation of the blade is an overall rigid-body displacement,the main deformation of the blade-fixture system occurs on the four clamping heads,and this fixture can effectively protect the blade from local deformation.The proposed clamping-sequence method reliably and effectively controls the local maximum deformation of the blade.The system stiffness is increased by 20 Hz,with each clamping force increased by 200 N.Both high-and low-frequency displacement in roughing milling or finishing milling are acceptable relative to the accuracy demand of blade machining.This fixture and an adaptive CNC machining process can achieve high accuracy in blade manufacturing.

Nature of complex number and complex-valued neural networks

We discuss the nature of complex number and its effect on complex-valued neural networks(CVNNs).After we review some examples of CVNN applications,we look back at the mathematical history to elucidate the features of complex number,in particular to confirm the importance of the phaseand-amplitude viewpoint for designing and constructing CVNNs to enhance the features.This viewpoint is essential in general to deal with waves such as electromagnetic wave and lightwave.Then,we point out that,although we represent a complex number as an ordered pair of real numbers for example,we can reduce ineffective degree of freedom in learning or self-organization in CVNNs to achieve better generalization characteristics.This merit is significantly useful not only for waverelated signal processing but also for general processing with frequency-domain treatment through Fourier transform.

POTENTIAL VORTICITY ADAPTATION PROCESS IN BAROCLINIC ATMOSPHERE

Starting from the primary equations and using the method of multiple timescale, theauthor derives three stages of baroclinic atm ospheric motion, i.e. the stage of geostrophicadaptation the stage of quasi-geostrophic potential vorticity adaptation and the balanced state.The potential vorticity adaptation comes into being through the process in which long wavesdisperse unbalanced energy. It is demonstrated by means of energy variation that under non-linear condition, the quasi-geostrophic evolution in which the potential vorticity conserves in-evitably leads to a quasi-balanced state. In this balanced state isolines of energy, stream lines andisohypses run parallel with each other. The first order approximation of this balanced stateis the so-called balance equation. Thus in nonlinear atmosphere this balanced state is moregeneral than the quasi-geostrophic balance. This result is significant for mid-range and long-range weather evolution.