利用Greenseeker法诊断甜菜氮素营养状况

利用Green Seeker法对不同氮素运筹下甜菜冠层归一化植被指数(normalized difference vegetation index,简称NDVI)进行测定,并分析甜菜叶面积指数(leaf area index,简称LAI)、比叶重(specific leaf weight,简称SLW)、叶片叶绿素含量以及全氮含量的变化。结果表明,甜菜冠层NDVI与叶片全氮含量呈极显著正相关,与叶片其他指标相关性不显著,NDVI与叶片全氮含量的拟合度在叶丛快速增长期最高。因此可见,利用Green Seeker法获取的NDVI能够反映甜菜叶片的氮素营养状况,Green Seeker法可以作为甜菜氮素营养快速无损检测的手段。

Seeker optimization algorithm:a novel stochastic search algorithm for global numerical optimization

A novel heuristic search algorithm called seeker op- timization algorithm （SOA） is proposed for the real-parameter optimization. The proposed SOA is based on simulating the act of human searching. In the SOA, search direction is based on empir- ical gradients by evaluating the response to the position changes, while step length is based on uncertainty reasoning by using a simple fuzzy rule. The effectiveness of the SOA is evaluated by using a challenging set of typically complex functions in compari- son to differential evolution （DE） and three modified particle swarm optimization （PSO） algorithms. The simulation results show that the performance of the SOA is superior or comparable to that of the other algorithms.

Photoelectric detection technology of laser seeker signals

The measurement of the rolling angle of the projectile is one of the key technologies for the terminal correction projectile.To improve the resolution accuracy of the rolling angle in the laser seeker weapon system, the imaging model of the detector, calculation model of the position and the signal-to-noise ratio(SNR) model of the circuit are built to derive both the correlation between the resolution error of the rolling angle and the spot position, and the relation between the position resolution error and the SNR. Then the influence of each parameter on the SNR is analyzed at large,and the parameters of the circuit are determined. Meanwhile, the SNR and noise voltage of the circuit are calculated according to the SNR model and the decay model of the laser energy. Finally,the actual photoelectric detection circuit is built, whose SNR is measured to be up to 53 d B. It can fully meet the requirement of0.5° for the resolution error of the rolling angle, thereby realizing the analysis of critical technology for photoelectric detection of laser seeker signals.

基于Green Seeker对小麦植被指数与产量形成模型的研究

小麦的产量受品种、光照、昼夜温差、降水、病虫害等自然灾害和耕地面积等综合因素的影响。通过小麦不同品种、不同灌溉方式、不同播种方式在小麦整个生育期的监测,研究小麦在不同的生长环境下建立与小麦的产量关系尤为重要。小麦冠层归一化植被指数(NDVI)以及比值植被指数(RVI)的变化情况,可利用主动遥感仪器——Green Seeker进行检测。对测量数据进行筛选,建立回归模型,解析小麦冠层植被指数与产量的变化规律,寻找基于NDVI和RVI与小麦产量的最佳估算模型,并验证小麦产量预测模型的有效性,对小麦产量预测的公式进行分析。

Signal processing method of a novel polarized array radar seeker

This paper proposes a novel polarized radar seeker based on the polarized antenna array. A fully polarized signal processing method for the proposed radar seeker is studied under the environments with electromagnetic interferences. A dual polarized antenna array is employed to transmit and receive the radar signals. The instantaneous polarization signal processing technique is used to detect and recognize the targets. The direction of arrival （DOA） of the target is measured through the spatial spectrum with high resolution for the polarized array radar seeker system. The fully polarized signal model of the polarized array radar seeker is formulated and a specific signal processing algorithm is expounded. The theoretical research and numerical simulation results demonstrate that the proposed radar seeker has good performances in target detection and electronic warfare. The research results can provide an effective technical approach to develop and research the new generation radar seeker.

The Echo Modelling and Simulation of the Semi-Active Radar Seeker against a Sea Skimming Target

This paper has proposed a new modelling and simulating technique for the echo of the semi-active radar seeker against the sea skimming target. The echo modelling is based on the electromagnetic scattering mechanisms. A modified Four-path model based on the radar detection scene is used to describe the multipath scattering between the target and rough sea surface. A Facet-based Small Slope Approximation (FBSSA) method is employed to calculate the scattering from the sea surface. The Physical Optics (PO) and the Equivalent Edge Current (EEC) Method is used to calculate the target scattering. In the echo simulations. The results present the original echo and the echo processed by the signal processing procedures, where the clutter and multipath effect can be observed.

New method for passive radar seeker to antagonize non-coherent radar decoy

Using super resolution direction of arrival（DOA） estimation algorithm to reduce the resolution angle is an effective method for passive radar seeker（PRS） to antagonize non-coherent radar decoy.Considering the power and correlation property between radar and non-coherent decoy,an improved subspace DOA estimation method based on traditional subspace algorithm is proposed.Because this new method uses the invariance property of noise subspace,compared with traditional MUSIC algorithm,it shows not only better resolution in condition of closely spaced sources,but also superior performance in case of different power or partially correlated sources.Using this new method,PRS can distinguish radar and non-coherent decoy with good performance.Both the simulation result and the experimental data confirm the performance of the method.

Influence of roll-pitch seeker DRR and parasitic loop on Lyapunov stability of guidance system

This paper focuses on the influence of the disturbance rejection rate(DRR)and parasitic loop parameters on the stability domain of the roll-pitch seeker's guidance system.The DRR models of the roll-pitch seeker caused by different types of disturbance torques and the scale deviation of different sensors are established.The optimal DRR model of the roll-pitch seeker,which contains the scale deviation model,is proposed by formula derivation.The model of the roll-pitch seeker's guidance system is established and equivalently simplified by the dimensionless method.The Lyapunov stability criterion for stability analysis of the guidance system is given by means of the passivity theorem and related definitions and lemmas.A simplified model of the roll-pitch seeker's guidance system,which is suitable for the Lyapunov stability criterion,is established by formula derivation and equivalent transformation.Three conditions that satisfy the Lyapunov stability criterion are obtained.Mathematical simulation with Nyquist plots is used to analyze the influence of different DRR parameters on the stability domain of the roll-pitch seeker's guidance system.Simulation results of this paper can provide reference for the stability analysis of systems related to the roll-pitch seeker.

Modified attitude pursuit guidance law for low-cost missiles using strap-down seekers

Attitude pursuit guidance law is suitable for low cost missiles.A strap-down seeker is used to achieve this guidance law.The additional angles of attack or sideslip caused by wind and by control system are considered as two disturbing factors which make attitude pursuit law impossible.Therefore,general attitude pursuit guidance law did not account for this two disturbing factors,because with those disturbing factors,it is difficult to apply.To solve the problem,the principle of strap-down seeker detecting target is investigated,the mathematical control model is established,then a modified attitude pursuit guidance law which employs the angular correction for those two disturbing factors is presented.It is proved that the modified attitude pursuit guidance law is appropriated to both in the presence of the additional angle of attack or sideslip via the simulations with the mathematical control model and Monte-Carlo method.

Brillouin scattering spectrum character extraction based on genetic algorithm and seeker optimization algorithm

A new hybrid optimization method based on genetic algorithm(GA)and seeker optimization algorithm(SOA)is presented in this paper.The hybrid algorithm optimizes SOA by using crossover and mutation operations in GA in order to improve the global search ability of SOA.Four algorithms,i.e.particle swarm optimization(PSO),SOA,GA and quantum-behaved particle swarm optimization(GA-QPSO)and GA-SOA are used to process the simulation and experimental data of Brillouin scattering spectrum(BSS)at different temperatures.The results show that GA-SOA improves the accuracy of extracting the center frequency shift and the minimum center frequency of Brillouin scattering spectrum compared with other three algorithms.The shift error is 0.203 MHz.Therefore,GA-SOA can be applied to the accurate extraction of BSS characteristics.

Seeker Optimization with Deep Learning Enabled Sentiment Analysis on Social Media;

World Wide Web enables its users to connect among themselves through social networks,forums,review sites,and blogs and these interactions produce huge volumes of data in various forms such as emotions,sentiments,views,etc.Sentiment Analysis(SA)is a text organization approach that is applied to categorize the sentiments under distinct classes such as positive,negative,and neutral.However,Sentiment Analysis is challenging to perform due to inadequate volume of labeled data in the domain of Natural Language Processing(NLP).Social networks produce interconnected and huge data which brings complexity in terms of expanding SA to an extensive array of applications.So,there is a need exists to develop a proper technique for both identification and classification of sentiments in social media.To get rid of these problems,Deep Learning methods and sentiment analysis are consolidated since the former is highly efficient owing to its automatic learning capability.The current study introduces a Seeker Optimization Algorithm with Deep Learning enabled SA and Classification(SOADL-SAC)for social media.The presented SOADL-SAC model involves the proper identification and classification of sentiments in social media.In order to attain this,SOADL-SAC model carries out data preprocessing to clean the input data.In addition,Glove technique is applied to generate the feature vectors.Moreover,Self-Head Multi-Attention based Gated Recurrent Unit(SHMA-GRU)model is exploited to recognize and classify the sentiments.Finally,Seeker Optimization Algorithm(SOA)is applied to fine-tune the hyperparameters involved in SHMA-GRU model which in turn enhances the classifier results.In order to validate the enhanced outcomes of the proposed SOADL-SAC model,various experiments were conducted on benchmark datasets.The experimental results inferred the better performance of SOADLSAC model over recent state-of-the-art approaches.

Line-of-sight rates extraction of roll-pitch seeker under anti-infrared decoy state

In this paper,the method of extracting guidance information such as the line-of-sight(LOS)rates under the anti-infrared decoy state for the roll-pitch seeker is researched.Coordinate systems which are used to describe the angles transform are defined.The LOS angles reconstruction model of the roll-pitch seeker in inertial space is established.A Kalman filter model for extracting LOS rates of the roll-pitch seeker is proposed.In this model,the target performs constant acceleration(CA)model maneuvers.The error model of LOS rates extraction under infrared decoy state is established.Several existing methods of extracting LOS rates under anti-infrared decoy state are listed in this paper.Different from the existing methods,a novel method that uses extrapolated values of target accelerations as filter measurements is proposed to solve the guidance information extraction problem under the anti-infrared decoy state.Numerical simulations are conducted to verify the effectiveness of the proposed method under different target maneuvering models such as the CA model,the CA extended model and the singer model.The simulation results show that the proposed method of extracting guidance information such as LOS rates for the rollpitch seeker under the anti-infrared decoy state is effective.

Proton Exchange Membrane Fuel Cell Modeling Based on Seeker Optimization Algorithm

Seeker optimization algorithm （SOA） has applications in continuous space of swarm intelligence. In the fields of proton exchange membrane fuel cell （PEMFC） modeling, SOA was proposed to research a set of optimized parameters in PEMFC polarization curve model. Experimental result showed that the mean square error of the optimization modeling strategy was only 6.9 × 10^-23. Hence, the optimization model could fit the experiment data with high precision.

Penetration Capability Comparison of the Same Anti-ship Missiles Between Millimeter and Centimeter Wave Seekers

This paper compares the penetration capabilities of the same type anti-ship missiles with millimeter wave(MMW)seeker and centimeter wave seeker,and constructs mathematical models of penetration probability and saturation attack number for all anti-ship missiles used in the countermeasure system,according to the rule which makes the ship-borne air defence system oppase as far as possible and equally,and combining the actual combat situation.It can be seen,from analysis of the countermeasure process between anti-ship missile and surface naval ship,that for the same type of anti-ship missile with different seekers,the main influence on the penetration capability is from electronic jamming system.Based on the built model,the penetration capabilities of the same type anti-ship missiles with MMW and centimeter wave seekers are simulated.The simulated results show that the penetration capability of MMW seeker is slightly better than that of the centimeter wave seeker and its saturation attack number is also influenced by the discovering probability greatly.Finally,some suggestions to get superior penetration effect are given for a commander to choose seeker type suitably.

Improving the target position detection in the crossed array trackers seeker using the pulses number distribution in the FOV

Seeking in a field of view(FOV) is influenced by the existence of jammers,noise,shine background or flying perturbations.All these factors may push the target out of the FOV and cause missing the target.In all the seekers the FOV is not fully exploited which means the target can be missed before becoming out of the FOV,this results of the nonlinearity of the reticle structure.In this paper,a novel method of the target position detection a crossed four slits or crossed array trackers(CAT) seeker will be designed,simulated and evaluated.The idea of this method depends on dividing the FOV into main regions up to a certain parameter,which is the pulses number;then,each main region will be divided into sub-regions up to a second parameter which will be the pulses distribution a spin period.The errors sources will be discussed and evaluated.Other new idea will be applied which is exploiting some area of the FOV where a part of the position data is missed in the information signal by pushing the target to the region where the information signal carries the total position data.

导引头稳定平台离散时间预设性能控制

针对现有离散时间预设性能控制方法对滑模趋近律依赖度高、抖振缺陷明显的难题,通过创建一种摆脱了滑模控制的设计新框架,为拦截弹导引头稳定平台提出了一种离散时间预设性能控制新方法。首先,设计一种离散时间性能函数对跟踪误差的收敛轨迹进行包络约束;然后,定义一种离散时间转换误差并将其用于构造一种新颖的反馈函数;设计离散时间控制律对新开发的反馈函数而不是转换误差进行镇定,不仅保证了所有跟踪误差均具有期望的预设性能,还摆脱了控制算法对滑模趋近律的依赖性,从根本上解决了控制抖振难题;最后,通过数值对比仿真验证了所提方法的有效性与优势。

反装甲导弹导引头抗干扰能力与关键技术发展

针对反装甲导弹面临的复杂战场环境、多样化作战目标和复杂干扰环境,分析其抗干扰能力和关键技术需求。分析反装甲导弹导引头面临的干扰威胁、抗干扰特点和不足,以科学高效提升反装甲导弹导引头抗干扰能力为目标,给出相关措施与建议。结果表明,该分析可为提升反装甲导引头抗干扰能力提供参考。

类THAAD导引头气动光学效应计算研究

针对类美国末段高空域防御(Terminal High Altitude Area Defense,THAAD)系统的红外导引头外形,开展了气动光学效应计算分析,并将其用于飞行器设计。利用国家数值风洞工程高速流场计算软件NNW-HyFLOW,考虑热化学非平衡效应和材料传热耦合效应,对导引头典型状态的流场进行了模拟,获得了流场的密度、温度、压力等参数和窗口的温度场参数。基于流场参数,利用HyFLOW气动光学传输效应计算功能,开展了红外光学传输成像计算;利用HyFLOW气动光学辐射效应计算模块,开展了流场和光学窗口的热辐射计算。计算结果表明,类THAAD导引头在30 km以上飞行时,流场和光学窗口基本不会影响目标信号的光学传输成像,但流场和窗口的热辐射效应会对导引头识别目标造成影响。不过随着飞行高度的升高,这种影响会减小。