A Stroke-Limitation AMD Control System with Variable Gain and Limited Area for High-Rise Buildings

Collisions between a moving mass and an anti-collision device increase structural responses and threaten structural safety.An active mass damper(AMD)with stroke limitations is often used to avoid collisions.However,a strokelimited AMD control system with a fixed limited area shortens the available AMD stroke and leads to significant control power.To solve this problem,the design approach with variable gain and limited area(VGLA)is proposed in this study.First,the boundary of variable-limited areas is calculated based on the real-time status of the moving mass.The variable gain(VG)expression at the variable limited area is deduced by considering the saturation of AMD stroke.Then,numerical simulations of a stroke-limited AMD control system with VGLA are conducted on a high-rise building structure.These numerical simulations show that the proposed approach has superior strokelimitation performance compared with a stroke-limited AMD control system with a fixed limited area.Finally,the proposed approach is validated through experiments on a four-story steel frame.

A 1.45GHz LNA with Low Power,Wide Variable Gain Range and Ultra Low Noise Degradation

A LNA with a novel variable gain solution is presented.Compared with the conventional variable gain solutions of LNA,which have more noise degradations when in low gain mode,this solution gives about 25dB variable gain range in 3dB steps,which would cause ultra low noise figure degradation by 0 3～0 5dB.In addition,extra power consumption is not needed by this solution compared with other solutions.

Compensation for secondary uncertainty in electro-hydraulic servo system by gain adaptive sliding mode variable structure control

Based on consideration of the differential relations between the immeasurable variables and measurable variables in electro-hydraulic servo system,adaptive dynamic recurrent fuzzy neural networks(ADRFNNs) were employed to identify the primary uncertainty and the mathematic model of the system was turned into an equivalent linear model with terms of secondary uncertainty.At the same time,gain adaptive sliding mode variable structure control(GASMVSC) was employed to synthesize the control effort.The results show that the unrealization problem caused by some system's immeasurable state variables in traditional fuzzy neural networks(TFNN) taking all state variables as its inputs is overcome.On the other hand,the identification by the ADRFNNs online with high accuracy and the adaptive function of the correction term's gain in the GASMVSC make the system possess strong robustness and improved steady accuracy,and the chattering phenomenon of the control effort is also suppressed effectively.

Sliding-mode control of path following for underactuated ships based on high gain observer

A nonlinear robust control strategy is proposed to force an underactuated surface ship to follow a predefined path with uncertain environmental disturbance and parameters.In the controller design,a high-gain observer is used to estimate velocities,thus only position and yaw angle measurements are required.The control problem of underactuated system is transformed into a control of fully actuated system through adopting an improved line-of-sight(LOS) guidance law.A sliding-mode controller is designed to eliminate the yaw angle error,and provide the control system robustness.The control law is proved semi-globally exponentially stable(SGES) by applying Lyapunov stability theory,and numerical simulation using real data of a monohull ship illustrates the effectiveness and robustness of the proposed methodology.

Variable Structure Model Reference Adaptive Control with Unknown High Frequency Gain Sign

可变结构模型引用为有比一个和未知高频率获得符号大的相对的度的工厂的适应控制被建议。一个切换的计划基于为靠近的环系统的第一个辅助错误设计的监视功能被介绍。在至多切换和追踪的错误的一个有限数字收敛到能被适当地选择一些设计参数使任意地小的一个剩余集合以后，在监视函数的管理下面，切换停止，这被显示出在至多切换和追踪的错误的一个有限数字收敛到能被适当地选择一些设计参数使任意地小的一个剩余集合以后。

A photoacoustic imaging system with variable gain at different depths

We established a photoacoustic imaging(PAI)system that can provide variable gain at different depths.The PAI system consists of a pulsed laser with an optical parametric oscillator working at a 728 nmwavelength and an imaging-acquisition-and-processing unit with an ultrasound transducer.Avoltage-controlled attenuator was used to realize variable gain at different depths when acquiring PAI signals.The proof-of-concept imaging results for variable gain at different depths were achieved using specic phantoms.Both resolution and optical contrast obtained through the results of variable gain for a targeted depth range are better than those of constant gain for all depths.To further testify the function,we imaged the sagittal section of the body of in vivo nude mice.In addition,we imaged an absorption sample embedded in a chicken breast tissue,reaching a maximum imaging depth of
4.6 cm.The results obtained using the proposed method showed better resolution and contrast than when using 50 dB gain for all depths.The depth range resolution was
1 mm,and the maximum imaging depth of our system reached
4.6 cm.Furthermore,blood vessels can be revealed and targeted depth range can be selected in nude mice imaging.

Gain-Scheduling H_∞ Autopilot Design for Tactical Missiles with Variable-Swept Wings

A new approach to gain-scheduling of H∞controllers is proposed for a cruise missile with variableswept wings( VSW) in bank-to-turn( BTT) mode. A nonlinear dynamic model is established and anticipant performance criterions are given at first. For the selected operating points,feedback robust controllers of threechannels are designed independently to restrain cross-channel couple disturbances and aerodynamic perturbations. Then,the sweepback and Ma number are selected to schedule controller gains iteratively to ensure all closed-loop poles locating inside the desired region. The proposed method here attempts to extend the performance of initial design obtained for a single arbitrary point to the whole linearized domain while maintaining the expected stability over the entire range of sweepback and full flight envelope. Some time-domain analysis procedures based on the proposed method are carried out and assessed,while the performance of tracking and robustness to aerodynamic perturbations in different situations are contrasted by some nonlinear simulations. Finally,the numerical simulations demonstrate that the proposed autopilot design method has better tracking performance and is robust,effective and feasible.

Motion stability and control of supercavitating vehicle with variable cavitation number

Cavitation number and speed are capable of variation during the motion of supercavitating vehicle underwater, for example, under the condition of accelerated motion stage and external disturbance. The dynamic model and control challenge associated with the longitudinal motion of supereavitating vehicle with variable cavitation number and speed have been explored. Based on the principle of cavity expansion independence the properties of cavity and the influence on planning force of body were researched. Calculation formula of efficiency of the fin was presented. Nonlinear dynamics model of variable cavitation number and speed supercavitating vehicle was established. Stabilities of the open-loop systems of different situations were analyzed. The simulations results of open-loop systems show that it is necessary to design a control method to control a supereavitating vehicle. A gain schedule controller with guaranteed H∞ performance was designed to stabilize the dive-plane dynamics of supercavitating vehicle under changing conditions.

A signal-summing programmable gain amplifier employing binary-weighted switching and constant-g--_m bias

A novel programmable gain amplifier（ PGA） based on a signal-summing topology is proposed. Different from conventional signal-summing variable gain amplifiers（ VGA）,a binary-weighted switching technique is employed to vary the current-steering transistors＇ aspect ratio to change their transconductance, and hence, an accurate gain step size of 6dB is achieved. The constant-g_m biasing technique and the matching of the transistors and resistors ensures that the gain of the proposed topology is independent of the variation of process, voltage and temperature（ PVT）. P-well NMOS（ Nmetal oxide semiconductor） transistors are utilized to eliminate the influence of back-gate effect which will induce gain error.The source-degeneration technique ensures good linearity performance at a low gain. The proposed PGA is fabricated in a0.18 μm CMOS（ complementary metal oxide semiconductor）process. The measurement results show a variable gain ranging from 0 to24 dB with a step size of 6 dB and a maximum gain error of 0. 3dB. A constant 3dB bandwidth of 210 MHz is achieved at different gain settings. The measured output 3rd intercept point（OIP3） and minimum noise figure（ NF） are20. 9 dBm and 11.1 dB, respectively. The whole PGA has a compact layout of 0.068 mm^2. The total power consumption is4. 8 mW under a 1. 8 V supply voltage.

Adaptive Processing Gain Data Services in Cellular CDMA in Presence of Soft Handoff with Truncated ARQ

An adaptive data transmission scheme based on variable spreading gain (VSG) is studied in cellular CDMA network in presence of soft handoff (HO). The processing gain is varied according to traffic intensity meet-ing a requirement on data bit error rate (BER). The overall performance improvement due to processing gain adaptation and soft HO is evaluated and compared with a fixed rate system. The influence of soft HO pa-rameters on rate adaptation and throughput and delay performance of data is indicated. Further truncated automatic repeat request (T-ARQ) is used in link layer to improve the performance of delay sensitive ser-vices. The joint impact of VSG based transmission in presence of soft handoff at physical layer and T-ARQ at link layer is evaluated. A variable packet size scheme is also studied to meet a constraint on packet loss.

CMOS Automatic Gain Control Circuit with DC Offset Cancellation for FM/cw Ladar

This paper presented an automatic gain control （AGC） circuit suitable for FM/cw ladar. The proposed architecture was based on two-stage variable gain amplifier （VGA） chain with a novel DC offset canceller circuit, which contained an improved Gilbert cell and a Gm-C feedback loop. To keep the VGA with a linearity in dB characteristic, an improved exponential gain control circuit was introduced. The AGC was implemented in 0.18 gm standard CMOS process. Simulation and measurement results verified that its gain ranged from -20 dB to 30 dB, and band- width ranged from 100 kHz to 10 MHz. Its power consumption was 19.8 mW under a voltage supply of 3.3 V.

Optical Gain Coefficient Measurements for 1-(4’-(Diphenylamino)-[1,1’-biphenyl]-4-yl)ethanone

In this study, the optical gain coefficient due to spontaneous emission for the conjugated compound 1-(4’-(diphenylamino)-[1,1’-biphenyl]-4-yl)ethanone (DBE) in two solvents, Tetrahydrofuran (THF) and Dichloromethane (DCM) was investigated using the variable stripe length method. The solutions were placed in 10 mm cuvettes and pumped optically with N2 laser (337 nm) with pulse duration of 1.2 ns and repetition rate of 10 Hz. A maximum net gain of 12 cm−1 for the compound in THF, and 7 cm−1 for the compound in DCM were recorded at the input energy of 162 μJ. The fluorescence quantum yields (∅f) of the compound were determined at the excitation wavelength of 337 nm using coumarin as a standard. The values of (∅f) for the samples in DCM and THF solvents were found to be 0.68 and 0.61, respectively. The high values of quantum yields suggest the possibility of using this material as an active media for lasing and for LED.

宽范围输入三电平半桥LLC变换器混合控制

针对传统变频(PFM)控制的LLC谐振变换器在宽电压输入条件下效率低的问题,提出一种三电平半桥LLC谐振变换器的变频-移相(PFM-PS)混合控制策略。首先,分析三电平半桥LLC谐振变换器的工作模态,建立其等效模型,获得了移相控制和变频控制下的电压增益曲线。其次,分析了变频控制的工作区间与软开关特性,推导得到了移相控制下实现软开关的最小占空比。通过混合控制策略,在升压时采用变频控制和在降压时采用移相控制,相较于全变频控制和全移相控制,混合控制可在较小频率变化范围内对电压进行升降压,在全增益范围内实现软开关,获得较宽的电压增益范围,提升了变换器的效率。最后,通过仿真和输入500~800 V/4.5 kW实验样机验证了所提出混合控制策略的有效性。

基于改进灰色预测单神经元PI的全超导托卡马克核聚变发电装置快控电源电流控制

全超导托卡马克核聚变发电装置(EAST)快控电源负载电感的电流受多种不确定环境因素的影响而难以预测,灰色预测无需精确对象模型,只需少量已知信息即可实现输出电流短期预测,已在EAST快控电源中有了一定研究应用。为解决灰色预测在EAST快控电源中对突变信号边沿预测精度低和预测延时时间长的问题,提出一种改进灰色预测算法实现输出电流预测。在一个开关周期内对输出电流进行等时长间隔采样4次作为原始序列,将滚动式采样预测改为逐周期采样预测,在实现灰色预测的过程中不必依赖过去几个周期的历史采样信息,只需本周期的4个原始采样值即可实现输出电流的预测。根据预测电流与参考电流误差自适应调整单神经元比例-积分(PI)控制的输出增益,实现输出电流的快速准确控制。仿真和实验结果表明,在EAST快控电源电流预测过程中所提出的改进灰色预测,对比传统灰色预测具有更高的预测精度和更小的预测延时,改进灰色预测变增益单神经元PI控制能够在减小电流超调的同时加快输出电流响应速度。

汽车线控转向系统自适应变增益传动比设计

转向传动比是影响车辆主动安全性及操纵稳定性的重要因素。为改善线控转向车辆在低附着系数路面下的转向特性,设计了随路面附着系数和车速变化而自适应调整的变增益传动比。建立汽车二自由度模型,分析影响横摆角速度增益的因素,并通过仿真得到影响因素与增益之间的数据关系。采用Min-Max归一化方法,将影响因素与横摆角速度增益之间的数据进行预处理,构建神经网络数据集;设计蛇算法优化的BP神经网络(SO-BP),利用预处理后的数据集对SO-BP神经网络进行训练,由此动态获取变横摆角速度增益。采用变横摆角速度增益与侧向加速度增益按比例综合的策略,设计线控转向变增益传动比。利用Simulink-CarSim搭建线控转向整车模型,分别在高附着系数路面双移线工况和低附着系数路面角阶跃工况下,将所设计的变增益传动比与传统定增益传动比进行对比分析。结果表明:高附着系数路面条件下,两种传动比车辆的行驶轨迹误差保持在3%以内,而变增益传动比车辆的转向盘转角峰值降低了9.1%;低附着系数路面条件下,变增益传动比车辆在中低车速下的横摆角速度稳态值降低了22.3%、峰值降低了24.6%,中高车速下的横摆角速度稳态值降低了6.6%、峰值降低了10.8%。变增益传动比不仅可以提高车辆在高附着系数路面上的转向灵敏度,也改善了在低附着系数路面上行驶的安全性与操纵性。

基于新型滑模观测器的PMSM无传感器控制

针对永磁同步电机无传感器控制中传统滑模观测器产生的抖振现象,提出新型滑模观测器。通过引入新型饱和函数代替符号函数,采用积分滑模面和可变增益,以抑制抖振,通过Lyapunov定理对其进行稳定性分析,并结合锁相环技术提取转速和转子位置信息。仿真结果表明:新型滑模观测器能够减小抖振,提升系统对转速和转子位置的估计精度。

基于非奇异负载转矩观测器的永磁同步电机抗扰动控制

针对永磁同步电机负载转矩波动及惯性负载的变化对控制性能的影响,采用一种非奇异负载滑模观测器实时辨识负载转矩,并将观测的负载转矩按比例转化为补偿电流值对控制系统进行前馈补偿,以降低负载扰动的影响;采用模型参考自适应算法辨识系统的转动惯量,并将观测出的惯量输入到负载转矩观测器中,减少惯性负载扰动的影响。实验结果表明,在不同工况下负载转矩和系统惯量变化时,设计的非奇异负载转矩滑模观测器补偿效果比一阶滑模负载转矩观测器补偿效果好,能够快速恢复到给定速度,系统的抗扰性能有很好改善。

振动筒传感器自动增益谐振电路仿真设计和测试

基于结型场效应管(JFET)可变电阻区和夹断区的特性,对振动筒传感器自动增益谐振电路进行仿真设计和测试。重点论述了激励信号占空比与振动筒电气特性的关系,自动增益控制谐振电路的实现方式和谐振电路激励端输出信号的波形、幅值和占空比设计思路。通过对振动筒的激励信号波形、幅值和占空比的设计,有效提高了传感器性能稳定和输出信号质量。

基于变增益NDOB的异步电机分段积分滑模控制

为改进异步电机的动态性和鲁棒性,设计了一种新型的滑模控制方法。首先,滑模面引入平滑的分段饱和函数,改进传统的积分滑模控制,在传统积分滑模控制的跟踪精度下,获得更好的暂态性能;其次,采用了一种超扭曲类算法的新型趋近律,削弱了系统的抖振,提高系统的稳态性能;最后,设计变增益非线性扰动观测器,可消除初始时刻观测器峰值,准确估计因模型不确定性、负载扰动等集总扰动。通过与传统积分滑模控制器对比,实验结果证明该方法具有更好的快速性与稳定性。

实际风况下萨沃纽斯风力机集群性能及布局规律研究

为探究风况条件对萨沃纽斯风力机集群功率输出和安装方向的影响,基于变转速控制策略和计算流体力学仿真结果,获得了集群在我国8个典型站点不同安装方向下的输出功率,分析了集群在实际风况下的最佳布局规律,并验证了规律的普适性。仿真结果表明:在沈阳、厦门、昆明、呼和浩特、青岛、喀什、大连以及郑州8个站点合理安装集群,可使单台机组的输出功率分别提升至原来的1.14、1.23、1.31、1.20、1.21、1.24、1.12、1.11倍;对于有明显单一主风能风向的地区,集群应正对此方向摆放;对于两个主风能风向相位差较大的地区,需选择两者中周围风能更丰富的方向排布集群;对于有3个主风能风向、主风能风向不明显或风能分布比较均匀的地区,应先使机组相互格挡的方位避开风能相对集中区,再选择风能资源较丰富的方向排布集群。该研究可使实际风况下萨沃纽斯风力机集群耦合增益最大化,并为复杂风场条件下集群安装方向的选择提供参考。