Robust Space-Time Adaptive Track-Before-Detect Algorithm Based on Persymmetry and Symmetric Spectrum

Underwater monopulse space-time adaptive track-before-detect method,which combines space-time adaptive detector(STAD)and the track-before-detect algorithm based on dynamic programming(DP-TBD),denoted as STAD-DP-TBD,can effectively detect low-speed weak targets.However,due to the complexity and variability of the underwater environment,it is difficult to obtain sufficient secondary data,resulting in a serious decline in the detection and tracking performance,and leading to poor robustness of the algorithm.In this paper,based on the adaptive matched filter(AMF)test and the RAO test,underwater monopulse AMF-DP-TBD algorithm and RAO-DP-TBD algorithm which incorporate persymmetry and symmetric spectrum,denoted as PSAMF-DP-TBD and PS-RAO-DP-TBD,are proposed and compared with the AMF-DP-TBD algorithm and RAO-DP-TBD algorithm based on persymmetry array,denoted as P-AMF-DP-TBD and P-RAO-DP-TBD.The simulation results show that the four methods can work normally with sufficient secondary data and slightly insufficient secondary data,but when the secondary data is severely insufficient,the P-AMF-DP-TBD and P-RAO-DP-TBD algorithms has failed while the PSAMF-DP-TBD and PS-RAO-DP-TBD algorithms still have good detection and tracking capabilities.

Adaptive detection of range-spread targets in homogeneous and partially homogeneous clutter plus subspace interference

Adaptive detection of range-spread targets is considered in the presence of subspace interference plus Gaussian clutter with unknown covariance matrix.The target signal and interference are supposed to lie in two linearly independent subspaces with deterministic but unknown coordinates.Relying on the two-step criteria,two adaptive detectors based on Gradient tests are proposed,in homogeneous and partially homogeneous clutter plus subspace interference,respectively.Both of the proposed detectors exhibit theoretically constant false alarm rate property against unknown clutter covariance matrix as well as the power level.Numerical results show that,the proposed detectors have better performance than their existing counterparts,especially for mismatches in the signal steering vectors.

Designing Adaptive Multiple Dependent State Sampling Plan for Accelerated Life Tests

A novel adaptive multiple dependent state sampling plan(AMDSSP)was designed to inspect products from a continuous manufacturing process under the accelerated life test(ALT)using both double sampling plan(DSP)and multiple dependent state sampling plan(MDSSP)concepts.Under accelerated conditions,the lifetime of a product follows the Weibull distribution with a known shape parameter,while the scale parameter can be determined using the acceleration factor(AF).The Arrhenius model is used to estimate AF when the damaging process is temperature-sensitive.An economic design of the proposed sampling plan was also considered for the ALT.A genetic algorithm with nonlinear optimization was used to estimate optimal plan parameters to minimize the average sample number(ASN)and total cost of inspection(TC)under both producer’s and consumer’s risks.Numerical results are presented to support the AMDSSP for the ALT,while performance comparisons between the AMDSSP,the MDSSP and a single sampling plan(SSP)for the ALT are discussed.Results indicated that the AMDSSP was more flexible and efficient for ASN and TC than the MDSSP and SSP plans under accelerated conditions.The AMDSSP also had a higher operating characteristic(OC)curve than both the existing sampling plans.Two real datasets of electronic devices for the ALT at high temperatures demonstrated the practicality and usefulness of the proposed sampling plan.

SYSTEM IDENTIFICATION OF ADAPTIVE TRUSS STRUCTURES USING PIEZOELECTRIC ACTIVE MEMBERS

Adaptive truss structures are a new kind of structures with integrated active members,whose dynamic characteristies can be beneficially modified to meet mission requirements.Active members containing actuating and sensing units are the major components of adaptive truss structures.Modeling of adaptive truss structures is a key step to analyze the structural dynamic characteristics.A new experimental modal analysis approach,in which active members are used as excitatiDn sources for modal test,has been proposed in this paper.The excitation forces generated by the active members, which are different from the excitation forces exerted on structures in the conventional modal test,are internal forces for the truss structures.The relation between internal excitation forces and external forces is revealed such that the traditional identification method can be adopted to obtain modal parameters of adaptive structures.Placement problem of the active member in adaptive truss structures is also discussed in this work. Modal test and analysis are conducted with a planar adaptive truss structure by using piezoelectric active members in order to verify the feasibility and effectiveness of the proposed method.

Five modified boundary scan adaptive test generation algorithms

To study the diagnostic problem of Wire-OR （W-O） interconnect fault of PCB （Printed Circuit Board）, five modified boundary scan adaptive algorithms for interconnect test are put forward. These algorithms apply Global-diagnosis sequence algorithm to replace the equal weight algorithm of primary test, and the test time is shortened without changing the fault diagnostic capability. The descriptions of five modified adaptive test algorithms are presented, and the capability comparison between the modified algorithm and the original algorithm is made to prove the validity of these algorithms.

Web-Based Adaptive Testing System

Due to the maturing of Internet technology, the adaptive testing can be utilized in the web-based environment and the examinee can take the test anywhere and any time. The purpose of the research is to apply item response theory （IRT）, adaptive testing theory and web-service technique to construct an XML format itembank and a system of web- based adaptive testing （WAT） by the framework of threetiered client server distance testing.

CD-CAT中基于SCAD惩罚和EM视角的在线标定方法开发——G-DINA模型

G-DINA(the generalizeddeterministic input,noisy and gate)模型限制条件少,应用范围广,满足大量心理与教育评估测验数据的要求。研究提出一种适用于G-DINA等模型的同时标定新题Q矩阵与项目参数的认知诊断计算机化自适应测验(CD-CAT)在线标定新方法SCADOCM,以期促进CD-CAT在实践中的推广与应用。本研究分别基于模拟题库以及真实题库进行研究,结果表明:相比传统的SIE方法,SCADOCM在各实验条件下均具有较为理想的标定精度与标定效率,应用前景较好;SIE方法不适用于饱和的G-DINA等模型,其各实验条件下的Q矩阵标定精度均较低。

Reducing Item Exposure in Computerized Adaptive Testing Systems Using Automatic Item Generation

This paper studies the technics of reducing item exposure by utilizing automatic item generation methods. Known test item calibration method uses item parameter estimation with the statistical data, collected during examinees prior testing. Disadvantage of the mentioned item calibration method is the item exposure; when test items become familiar to the examinees. To reduce the item exposure, automatic item generation method is used, where item models are being constructed based on already calibrated test items without losing already estimated item parameters. A technic of item model extraction method from the already calibrated and therefore exposed test items described, which can be used by the test item development specialists to integrate automatic item generation principles with the existing testing applications.

非参数CD-CAT题库Q矩阵优化设计

开展非参数CD-CAT题库Q矩阵的优化设计,并将它用于指导题库题目编制或选择,且它无需模型参数估计,这对于促进非参数CD-CAT进入课堂评价至关重要.受p-优化的启发,该文提出比例法生成优化Q矩阵,同时将已有的参数化模型题库设计方法推广到非参数化题库Q矩阵的优化设计.模拟研究结果显示:比例法和推广的融合法都有较好表现,而且当题库量较少时比例法更有优势.

CAT分层类曝光控制策略研究新进展

计算机化自适应测验(computerized adaptive testing,CAT)可以根据每一名考生的不同作答进行自适应选题,提高了测验精度.但高精度也伴随着高曝光风险,分层类项目曝光控制策略作为项目曝光控制的方法之一,是近年来曝光控制研究领域的热点.同时,反应时(RT)的收集是CAT的一大优势,RT对于测验的实施具有重要价值.该文综合介绍了传统的分层策略,并结合RT的分层策略探讨当前分层策略应用于CAT项目曝光控制中存在的问题及其未来研究方向.

Designing of A Computerized Cognitive Adaptive Testing Model

Therecouldbenoscienceasweknowitwithoutmeasurement.Testing,includingallformsoflanguagetestingandpsychometricsitself,isoneformofmeasurement.Alanguagetestmaybedefinedasaprocedureforelicitinglanguageperformanceandaprocedureforassessingthatperformance.How...

Adaptive Signal Conditioning Technology in Fighter Weapon System Test

In order to realize the real-time and precise test for a weapon system of a certain type of fighter,a signal classification method according to attributes is proposed,common input channels for multiple signals are configured optimally,and a test adapter and an adaptive signal conditioning module is designed. The hardware of conditioning module can be configured flexibly and the programmable test range can be adjusted owing to programmable multiplexer. An FPGA adaptive filter is designed by the calculated filter coefficient vectors with LMS method to solve the problem of parallel test of fighter weapon system in electromagnetic interference environment. The adaptive signal conditioning technology is characterized by high efficiency,precision and integration. Its application makes the test system successful to conduct real-time and parallel test for a weapon system,which is developed based on VXI bus and virtual-instrument technology.

Fuzzy Model Free Adaptive Control for Rotor Blade Full-Scale Static Testing

To eliminate the node traction coupling during wind turbine blade full-scale static testing,a model free adaptive control algorithm is presented based on fuzzy control performance function compensation. Based on the universal model theory,the fuzzy model free adaptive control( FMFAC) algorithm is designed by configuring the spot static testing experiences as compensation function F( ·). Then the algorithm implementation process is provided and its quick convergence is proved. Using software to establish static load coupling model of multi-nodes,simulate and verify the validity of FMFAC algorithm,which is applied to wind turbines blade full-scale static testing. The results show that the adaptive decoupling ability of FMFAC is better. The traction of four load points can stay steady and change coordinately. Process error is not over ± 6 k N. The error rate is lower than 1% in special phase.This algorithm effectively eliminates the traction coupling of the static testing process,and makes wind turbine blade testing steadily.

Study on rate ripple and its adaptive suppression method in inertia guidance test equipment

This paper discusses causes of the rate ripple in inertia guidance test equipment IGET, systematically analyses their effects an the rate ripple in IGTE. The analysis result shows： The rate ripple caused by the periodic errors of inductosyn and angular encoder is higher at high speed than that caused by magnetic ripple torque and friction torque, and it cannot be eliminated by adjusting control parameters of the system. And based on the nonlinear adaptive control system theory, the paper puts forward a new control system scheme to eliminate the rate ripple caused by the periodic errors of inductosyn and angular encoder, develops the adaptive control rules and makes simulation and test. Experimental result shows a significant improvement on those tables for the period disturbs under the system scheme designed. By this plan, with the input of rate 200°/s, the rate ripple falls from 5°/s to 0. 4°/s within about 6s adaptive adjustment time, being a twelfth of before adaptation, which can not be reached by common classical controls. The experimental results conform with the simulation, which proves the validity and practicability of the plan.

Harmonic amplitude-phase adaptive control and its application in three-axis simulators

This paper proposes a compensation method for using the Harmonic Amplitude-Phase Adaptive Control(HAPAC)to increase the precision of sinusoidal motion simulators. It also expounds on the HAPAC principle and structural disposition, develops the HAPAC control laws and analyzes the system stability in the HAPAC. A method for further improving the precision using online identification of the system’s frequency-response models is presented. The tested data and tracking errors of the simulator demonstrate that the HAPAC makes the sinusoidal motions achieve higher precision than the common classical controls. The HAPAC can also be used in other tracking systems of precision sinusoidal motions.

A Test Items Knowledge Library System for Adaptive Learning

A test items knowledge library system of for adaptive learning is proposed in this paper. The first step is to carry out the quantity and quality analysis of the test items by using the Bloom＇s revised taxonomy and scale anchoring respectively to produce the characteristics for test items. A smoothing method of arbitrary anchoring revised from scale anchoring is first proposed to make tests more accurate in distinguishing test levels. In addition, raised three dimensional indicators based on the Bloom＇s revised taxonomy are adopted to validate test contents and therefore it concretely describes the examining function of items. The items obtained have the precise and concrete properties; an item knowledge library is therefore constructed combining teaching materials and items using the technologies of ontology and knowledge management. Finally, a knowledge library system of test items is established to achieve the purpose of adaptive learning for learners.

CAT-1超导磁悬浮系统的平衡分析与永磁实验装置设计

天环一号(CAT-1)是国内首个采用磁悬浮偶极场磁体设计的磁约束等离子体装置。本文根据CAT-1装置总体目标和参数设计要求,采用线电流简化模型,基于矢量磁场、力学平衡及动力学等方法,完成了超导磁悬浮系统的平衡稳定分析,给出了参数设计结果;初步设计出简化的永磁悬浮实验装置,用于检验超导磁悬浮系统稳定性及参数可靠性。结果表明:对于CAT-1装置的悬浮磁体1200 kg、电流5 MA、悬浮距离2.0 m设计目标,托举线圈半径最优值为1.7 m,相应的电流为3.49 kA,为实现对悬浮磁体偏移运动的有效阻减及控制,平衡点附近工作区域应限制在垂直位移Δz<0.1 m、水平位移Δer<0.05 m、倾斜角位移Δα<π/24;分析了TSR线圈对悬浮线圈的影响,计算显示TSR与悬浮线圈产生对向漂移,漂移幅度与径向位置有关,同时TSR线圈侧原本闭合磁力线被破坏,造成输运粒子损失;采用1.5 kg永磁完成了悬浮实验装置概念设计,分析表明永磁体与托举线圈间距0.1 m,铜导托举线圈电流895 A,满足控制对响应速度的要求。

Design of a large-scale model for wind tunnel test of a multiadaptive flap concept

The design and application of morphing systems are ongoing issues compelling the aviation industry.The Clean Sky-program represents the most significant aeronautical research ever launched in Europe on advanced technologies for greening next-generation aircraft.The primary purpose of the program is to develop new concepts aimed at decreasing the effects of aviation on the environment,increasing reliability,and promoting eco-friendly mobility.These ambitions are pursued through research on enabling technologies fostering noise and gas emissions reduction,mainly by improving aircraft aerodynamic performances.Within the Clean Sky framework,a multimodal morphing flap device was designed based on tight industrial requirements and tailored for large civil aircraft applications.The flap is deployed in one unique setting,and its cross section is morphed differently in take-off and landing to get the necessary extra lift for the specific flight phase.Moreover,during the cruise,the tip of the flap is deflected for load control and induced drag reduction.Before manufacturing the first flap prototype,a high-speed(Ma=0.3),large-scale test campaign(geometric scale factor 1:3)was deemed necessary to validate the performance improvements brought by this novel system at the aircraft level.On the other hand,the geometrical scaling of the flap prototype was considered impracticable due to the unscalability of the embedded mechanisms and actuators for shape transition.Therefore,a new architecture was conceived for the flap model to comply with the scaled dimensions requirements,withstand the relevant loads expected during the wind tunnel tests and emulate the shape transition capabilities of the true-scale flap.Simplified strategies were developed to effectively morph the model during wind tunnel tests while ensuring the robustness of each morphed configuration and maintaining adequate stiffness levels to prevent undesirable deviations from the intended aerodynamic shapes.Additionally,a simplified design was conceived for the flap-wing interface,allowing for quick adjustments of the flap setting and enabling load transmission paths like those arising between the full-scale flap and the wing.The design process followed for the definition of this challenging wind tunnel model has been addressed in this work,covering the definition of the conceptual layout,the numerical evaluation of the most severe loads expected during the test,and the verification of the structural layout by means of advanced finite element analyses.

Adaptive detector design of MIMO radar with unknown covariance matrix

The problem of detecting signal with multiple input mul-tiple output （MIMO） radar in correlated Gaussian clutter dominated scenario with unknown covariance matrix is dealt with. The gen-eral MIMO model, with widely separated sub-arrays and co-located antennas at each sub-array, is adopted. Firstly, the generalized likelihood ratio test （GLRT） with known covariance matrix is ob-tained, and then the Rao and Wald detectors are devised, which have proved that the Rao and Wald test coincide with GLRT detec-tor. To make the detectors fully adaptive, the secondary data with signal-free will be collected to estimate the covariance. The per-formance of the proposed detector is analyzed, however, it is just ancillary. A thorough performance assessment by several numer-ical examples is also given, which has considered the sense with co-located antennas configure of transmitters and receivers array. The results show that the performance the proposed adaptive de-tector is better than LJ-GLRT, and the loss can be acceptable in comparison to their non-adaptive counterparts.

Adaptive detection in the presence of signal mismatch

The problem of adaptive detection in the situation of signal mismatch is considered; that is, the actual signal steering vector is not aligned with the nominal one. Two novel tunable detectors are proposed. They can control the degree to which the mismatched signals are rejected. Remarkably, it is found that they both cover existing famous detectors as their special cases. More importantly, they possess the constant false alarm rate（CFAR）property and achieve enhanced mismatched signal rejection or improved robustness than their natural competitors. Besides, they can provide slightly better matched signals detection performance than the existing detectors.