Inversion-based attenuation compensation with dip constraint

Instability is an inherent problem with the attenuation compensation methods and has been partially relieved by using the inverse scheme.However,the conventional inversion-based attenuation compensation approaches ignore the important prior information of the seismic dip.Thus,the compensated result appears to be distorted spatial continuity and has a low signal-to-noise ratio(S/N).To alleviate this issue,we have incorporated the seismic dip information into the inversion framework and have developed a dip-constrained attenuation compensation(DCAC)algorithm.The seismic dip information,calculated from the poststack seismic data,is the key to construct a dip constraint term.Benefiting from the introduction of the seismic dip constraint,the DCAC approach maintains the numerical stability and preserves the spatial continuity of the compensated result.Synthetic and field data examples demonstrate that the proposed method can not only improve seismic resolution,but also protect the continuity of seismic data.

An approach of motion compensation and ISAR imaging for micro-motion targets

Inverse synthetic aperture radar(ISAR)imaging of the target with the non-rigid body is very important in the field of radar signal processing.In this paper,a motion compensation method combined with the preprocessing and global technique is proposed to reduce the influence of micro-motion components in the fast time domain,and the micro-Doppler(m-D)signal in the slow time domain is separated by the improved complex-valued empirical-mode decomposition(CEMD)algorithm,which makes the m-D signal more effectively distinguishable from the signal for the main body by translating the target to the Doppler center.Then,a better focused ISAR image of the target with the non-rigid body can be obtained consequently.Results of the simulated and raw data demonstrate the effectiveness of the algorithm.

Near-surface absorption compensation technology and its application in the Daqing Oilfields

高周波的地震数据部件能严重在 unconsolidated 在震波繁殖期间被稀释(低速度) 层，导致减少的地震分辨率和 signal-to-noise (S/N ) 比率。在这篇论文，基于维纳过滤器理论，首先，为近表面的吸收变细赔偿的反的过滤器计算被直接波浪的分析完成光谱从不同距离的部件接近表面。直接波浪被雷管产生在在洞射击上面并且被接收装置在表面上获得。空间地变化的反的过滤器被设计补偿因为 3D 的频率变细预先叠 CRG (普通接收装置集合) 数据。在把过滤器用于 CRG 数据以后，高频率部件被补偿，低频率维持了。地震决定和 S/N 比率与合成震动图更好被提高并且匹配并且更好满足地质的解释的需要。

ROBUST SMITH PREDICTIVE CONTROLLER FOR PROCESS WITH INVERSE RESPONSE

Smith predictor known as the time delay compensator was extended to control the process with inverse response.Modern robust control theory was employed to design the robust controller,which has only one parameter to be determined with compromise among the rise time,undershoot,robustness and capability to reject disturbance of the closed loop system.The former two specifications can be assessed quantitatively and the latter two qualitatively.Examples show that the proposed method has significant improvements and wide applicable ranges for inverse response process.

THE SYSTEM COMPENSATION OF ISAR

A method for compensating the amplitude-phase distortion of ISAR system is de-scribed.This system compensation can be separated into two parts:the compensation of thesystem before the mixer and the compensation of the system after the mixer.The experimentalresults of the compensation in microwave dark room are given.It is shown that the methodpresented is effective.

Dynamic Velocity Feed-Forward Compensation Control with RBF-NN System Identification for Industrial Robots

A dynamic velocity feed-forward compensation control (DVFCC) approach with RBF neural network (RBF-NN) dynamic model identification was presented for the adaptive trajectory tracking of industrial robots.The proposed control approach combined the advantages of traditional feedback closed-loop position control and computed torque control based on inverse dynamic model.The feed-forward compensator used a nominal robot dynamics as accurate dynamic model and on-line identification with RBF-NN as uncertain part to improve dynamic modeling accuracy.The proposed compensation was applied as velocity feed-forward by an inverse velocity controller that can convert torque signal into velocity in the standard industrial controller.Then,the need for a torque control interface was avoided in the real-time dynamic control of industrial robot.The simulations and experiments were carried out on a gas cutting manipulator.The results show that the proposed control approach can reduce steady-state error,suppress overshoot and enhance tracking accuracy and efficiency in joint space and Cartesian space,especially under highspeed condition.

X-band inverse class-F GaN internally-matched power amplifier

An X-band inverse class-F power amplifier is realized by a 1-mm Al Ga N/Ga N high electron mobility transistor（HEMT）.The intrinsic and parasitic components inside the transistor,especially output capacitor Cds,influence the harmonic impedance heavily at the X-band,so compensation design is used for meeting the harmonic condition of inverse class-F on the current source plane.Experiment results show that,in the continuous-wave mode,the power amplifier achieves 61.7% power added efficiency（PAE）,which is 16.3% higher than the class-AB power amplifier realized by the same kind of HEMT.To the best of our knowledge,this is the first inverse class-F Ga N internally-matched power amplifier,and the PAE is quite high at the X-band.

A New CMOS Current Reference with High Order Temperature Compensation

A new high order CMOS temperature compensated current reference is proposed in this paper, which is accomplished by two first order temperature compensation current references. The novel circuit exploits the temperature characteristics of integrated-circuit resistors and gate-source voltage of MOS transistors working in weak inversion. The proposed circuit, designed with a 0.6 Izm standard CMOS technology, gives a good temperature coefficient of 31ppm/℃ [-50-100℃] at a 1.8V supply, and also achieves line regulation of 0.01%/V and-120dB PSR at 1 MHz. Comparing with other presented work, the proposed circuit shows better temperature coefficient and Line regulation.

聚合物三腔微管挤出口模结构对胀大变形的影响

聚合物熔体的模内流动状态与模外胀大变形直接影响微挤出制品的成型质量。文中基于Carreau模型,采用数值模拟方法,研究了聚合物三腔微管挤出过程中口模壁厚差与空心度结构特征对胀大变形行为的影响。结果表明,影响挤出胀大变形程度的关键因素是口模出口附近的轴向速度分布;内外壁厚差会导致较大壁厚位置处对应的型坯厚度增大,而较小壁厚位置处的型坯厚度减小,壁厚差变化对薄壁区域壁厚变形影响较大,达到91.4%;空心度减小能提升口模出口附近轴向速度分布均匀性,减小了70.1%的变形程度;基于胀大变形规律逆向补偿设计了口模形状与尺寸,明显改善了制品成型质量。研究结果对聚合物多腔微管的口模结构优化设计具有理论意义与工程应用价值。

一种联合TDCM和PFA的空间目标大转角ISAR成像方法

空间目标态势感知是当前航天技术领域的研究热点,逆合成孔径雷达(Inverse Synthetic Aperture Radar, ISAR)是空间目标感知的一种有效手段。为了得到利于目标鉴别的高分辨二维ISAR图像,需要通过增大积累转角来提高方位向分辨率。但是,随着转角的增大,平动与转动之间的耦合增大,使得传统的先平动补偿、后利用转动成像的两步式成像方法不再适用。本文提出了一种结合时域信号共轭相乘(Time Domain Conjugate Multiplication, TDCM)处理与极坐标格式算法(Polar Format Algorithm, PFA)的成像算法,首先利用雷达回波的二维相干性,通过TDCM处理进行平动粗补偿,然后借助PFA的插值操作校正大转角引起的散射点越分辨单元走动(Motion Through Resolution Cell, MTRC)并估计目标相对转动参数。通过迭代处理,持续对平动和转动参数进行优化,提升运动补偿效果。仿真验证了所提成像算法的有效性,与传统算法相比,成像聚焦性更好。

分布式移动水声传感网络地声参数反演

提出使用分布式移动水声传感网络以实现大面积海域地声参数的快速反演。将分布式网络节点投影合成不同阵元间距的水平线阵,采用频域相干目标函数,进行匹配场地声参数反演。同时,将定位误差视为一个参量进行反演,结合对水平波数修正的多普勒补偿,提高移动网络反演的鲁棒性。数值仿真和海试数据处理结果验证了分布式移动水声传感网络地声参数反演方法的有效性。

δ相时效态GH4169合金Zerilli-Armstrong本构模型及其参数反求方法

在Gleeble-1500D型热模拟试验机上进行了δ相时效态GH4169合金的高温压缩试验。试验温度为950~1040℃、应变速率为0.005~1 s^(-1)。为了能建立准确描述该合金流动行为的本构模型,考虑应变对Zerilli-Armstrong本构模型材料参数的影响,提出并采用了一种基于多岛遗传算法的参数反求方法建立了该材料考虑应变补偿的Zerilli-Armstrong本构模型。借助相关系数、平均绝对相对误差等标准统计参数定量评估了该本构模型预测的准确性。结果表明:考虑应变补偿的Zerilli-Armstrong本构模型具有较高的预测准确性,其相关系数和平均绝对相对误差分别为0.996和3.189%。

天基逆合成孔径雷达脉内脉间运动补偿及高分辨成像

近年来,太空态势感知在军用和民用领域都得到了越来越多的关注。天基逆合成孔径雷达(SBISAR)能够实现对空间目标的高分辨成像,支撑部件提取、姿态估计、类型识别等后续任务,是太空态势感知的重要工具。然而,在SBISAR成像场景下,平台与空间机动目标间存在复杂的相对高速运动,传统距离-多普勒成像方法不再适用,必须进行运动补偿。本文针对高速径向速度下传统“停—走—停”模型失效、长相干积累时间内目标转速不一致的两个典型误差来源,分别设计了脉内运动及脉间运动补偿算法。首先,建立SBISAR成像的信号模型。然后,基于最小熵准则构建参数估计代价函数,通过估计目标对应回波信号的调频率,构造补偿项进而实现脉内补偿。同时,建立图像熵代价函数,在估计转动参数后,完成对目标转动的空变相位补偿。所提算法有效解决了天基高速机动背景下传统距离-多普勒成像方法的距离像展宽、方位散焦问题,实现了SBISAR对空间目标的高分辨成像。通过基于仿真数据的实验分析,验证了所提算法的有效性。

先进高强度双相钢弯扭复合回弹补偿控制研究

针对先进高强度双相钢弯扭复合回弹的预测与补偿问题,在弯扭复合回弹试验的基础上建立了有限元模型并进行了仿真模拟。首先,利用DP600材料在弯扭复合回弹试验中回弹量较大的特点,进行了单向拉伸试验和加载-卸载-反向加载的拉压试验以测定DP600的力学特性。其次,分别采用Ls-dyna提供的4种弹塑性材料模型建立了单向拉伸和拉压试验有限元模型,通过Ls-opt迭代求解筛选出合适的材料模型及参数,结果表明,采用MAT125材料模型预测的数值更接近弯扭复合回弹试验数据。最后,通过反向截面补偿法推导出底部支撑距离移动公式,通过反向位移补偿法和偏置曲面得到模具面,对弯扭复合回弹结果分别进行补偿。发现利用反向位移补偿法,并通过偏置曲面的方式,能够对在上压杆偏转角度增加时诱发的弯扭复合回弹进行有效补偿控制。

An Inverse Compensation Formulation Principle of Long Effective Fidelity Scheme of the Evolution Problems

Following the instant square conservative scheme, implicit, explicit and semiimplicit schemes have also been formulated. Based on the theory of perfect square conservative scheme, which has assimilated the reasonable part of the idea of formulating the explicit scheme by adjustable dissipation, and the idea of actualizing the implicit scheme via 'instant linearization', a general compensation formulation

A Time－space Domain Backprojection Method for Ray Inversion in Layered Medium

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基于FxRLS自适应逆补偿的振动控制策略研究

为满足航天器中搭载的高精度设备对振动环境要求的不断提高,提出将滤波-x最小递归二乘(filtered-x recursive least square, FxRLS)自适应算法与逆补偿法结合应用于隔振系统中。首先从系统动力学模型和自适应逆补偿算法两方面展开理论分析,通过FxRLS自适应控制对系统响应进行精确跟踪,利用逆补偿控制对系统振动主动消除。为验证控制策略的有效性,在Simulink和实验环境中,搭建验证系统。结果表明:对不同激励信号下的跟踪性能及振动消除效果进行仿真分析,自适应逆补偿输出的控制信号能有效跟踪负载端振动信号,跟踪率最高可达99.97%。相比滤波-x最小均方(filtered-x least mean square, FxLMS),FxRLS在跟踪速度和跟踪精度两方面的综合性能更优。应用FxRLS自适应逆补偿控制后,试验显示随机扰动隔振率达到66.7%。试验与仿真结果都证明控制策略的有效性。

全球导航卫星系统-声呐组合观测模型分类体系

本文回顾了海底大地测量全球导航卫星系统-声呐观测模型近二十年来的发展,以声速误差处理为主线给出了全球导航卫星系统-声呐观测模型的分类体系,按函数模型、随机模型和约束条件进行了归纳,探讨了未来发展方向。研究表明:测距定位模型无需现场声速剖面测量,但需解决声速垂向梯度影响的有效参数化估计或改正问题;海底大地测量更为关注声速时空变化对观测值影响,为此推荐采用声速场误差加性补偿模型及其导出的声速场参数间接估计模型;海底局域网阵列存在类似共模环境误差,具有提升海洋环境参数估计及海底定位精度的能力。

基于最小二乘法的逆运动学优化补偿算法

为解决全参数补偿导致逆运动学求解算法失效的问题,提出基于最小二乘法的逆运动学优化补偿算法。首先,该算法使用全参数补偿正运动学减小机器人末端位置误差;然后,使用不改变逆运动学求解算法的十参数直接补偿逆运动学求解关节角度;最后,建立微分方程组,并使用最小二乘法求解关节角度误差,对逆运动学求解算法进行优化补偿。在MATLAB中使用该算法对3组关节角度进行逆运动学解算,计算误差在0.000 1°左右;使用自主研发控制系统在6R型工业机器人进行实验,测得全参数补偿后的位置误差比转换十参数补偿后减小40.66%。实验结果证明逆运动学优化补偿算法的有效性。