Robust control with compensation of adaptive model for dual-stage inertially stabilized platform

To achieve excellent tracking accuracy,a coarse-fine dual-stage control system is chosen for inertially stabilized platform.The coarse stage is a conventional inertially stabilized platform,and the fine stage is a secondary servo mechanism to control lens motion in the imaging optical path.Firstly,the dual-stage dynamics is mathematically modeled as a coupling multi-input multi-output(MIMO)control system.Then,by incorporating compensation of adaptive model to deal with parameter variations and nonlinearity,a systematic robust H∞control scheme is designed,which can achieve good tracking performance,as well as improve system robustness against model uncertainties.Lyapunov stability analysis confirmed the stability of the overall control system.Finally,simulation and experiment results are provided to demonstrate the feasibility and effectiveness of the proposed control design method.

Robust lag synchronization between two different chaotic systems via dual-stage impulsive control

In this paper, an improved impulsive lag synchronization scheme for different chaotic systems with parametric uncertainties is proposed. Based on the new definition of synchronization with error bound and a novel impulsive control scheme （the so-called dual-stage impulsive control）, some new and less conservative sufficient conditions are established to guarantee that the error dynamics can converge to a predetermined level, which is more reasonable and rigorous than the existing results. In particular, some simpler and more convenient conditions are derived by taking the same impulsive distances and control gains. Finally, some numerical simulations for the Lorenz system and the Chen system are given to demonstrate the effectiveness and feasibility of the proposed method.

Design and Experiment of Vertical Motion Dual-stage with Piezo-actuated Nanopositioning Stage

Nanopositioning stage based on piezoelectric(PZT)actuators and flexure mechanisms has been widely used in dual-stage.Its favorable positioning accuracy and dynamic response can guarantee the high performance of the dual-stage.Here the vertical axis motion dual-stage is designed with piezoelectric actuator for the fine-stage and ball-screw drive integrated with wedge sliding mechanisms for the coarse-stage.The aim of the dual-stage is to meet the stringent requirement of scanning over a relative large range with high accuracy.The design results of the piezo-actuated nanopositioning stage show good static and dynamic performance,validated by the simulation of finite element analysis(FEA).Hysteresis nonlinearity due to the use of piezoelectric stacks for actuation is studied and compensated by aproportional-integral(PI)feedback controller.To qualify the design of the motion ranges and resolutions,an experiment platform is established.The experimental results show that the proposed dual-stage has a full range of 12 mm with the resolution of 40 nm.Guideline is provided for the design methodology of the vertical motion dual-range stages.

Implementation of Mooring Automatic Positioning System for Deepwater Semi-Submersible Platform Based on Dual-Stage Actuator

The automatic positioning control of mooring system for deepwater semi-submersible platform has become a key issue in the research and development field of deep-sea resources. The Dual- Stage Actuator (DSA) proposed in this paper can replace the single actuator to achieve the high speed and high precision positioning by cooperative control. The relative model and control algorithm of motion trajectory (CAMT) are designed and validated, which proves that the method proposed in this paper is effective.

Dual-stage Optimal Iterative Learning Control for Nonlinear Non-affine Discrete-time Systems

根据沿着重复轴的一种新动态 linearization 技术，双阶段的最佳的反复的学习控制为非线性、非仿射的分离时间的系统被介绍。双阶段显示二个最佳的学习阶段分别地被设计反复地改进控制输入顺序和学习获得。主要特征是控制器设计和集中分析仅仅取决于动态系统的 I/O 数据。换句话说，没有知道系统的任何另外的知识，我们能容易选择控制参数。模拟学习沿着重复轴说明介绍方法的几何集中，在哪个马路的一个例子控制为它的内在的工程重要性是引人注目的交通反复的学习。

Tomographic particle image velocimetry measurement on three-dimensional swirling flow in dual-stage counter-rotating swirler

Three-Dimensional(3D)swirling flow structures,generated by a counter-rotating dualstage swirler in a confined chamber with a confinement ratio of 1.53,were experimentally investigated at Re=2.3×10^(5)using Tomographic Particle Image Velocimetry(Tomo-PIV)and planar Particle Image Velocimetry(PIV).Based on the analysis of the 3D time-averaged swirling flow structures and 3D Proper Orthogonal Decomposition(POD)of the Tomo-PIV data,typical coherent flow structures,including the Corner Recirculation Zone(CRZ),Central Recirculation Zone(CTRZ),and Lip Recirculation Zone(LRZ),were extracted.The counter-rotating dual-stage swirler with a Venturi flare generates the independence process of vortex breakdown from the main stage and pilot stage,leading to the formation of an LRZ and a smaller CTRZ near the nozzle outlet.The confinement squeezes the CRZ to the corner and causes a reverse rotation flow to limit the shape of the CTRZ.A large-scale flow structure caused by the main stage features an explosive breakup,flapping,and Precessing Vortex Core(PVC).The explosive breakup mode dominates the swirling flow structures owing to the expansion and construction of the main jet,whereas the flapping mode is related to the wake perturbation.Confinement limits the expansion of PVC and causes it to contract after the impacting area.

Plasma transport simulation under different conditions and optimization analysis of dual-stage grid ion thruster

In order to study the extraction and acceleration mechanism of the dual-stage grid,a three-dimensional model based on the Particle-In-Cell/Monte Carlo Collision(PIC/MCC)method is performed.Dual-stage grid ion thruster is a new type of electrostatic ion thruster,which can break through the limitations of traditional gridded ion thrusters,and greatly improve the specific impulse.The high performance also makes the grid sensitive to operating parameters.In this paper,the influence of grid parameters on xenon ion thruster’s performance in a wide range is systematically simulated,and the optimal operating condition is given.Both the over-focusing of the plume,and the transparency of the screen grid are improved,and the grid corrosion is reduced through simulation optimization.The specific impulse under the given working conditions is 9877.24 s and the thrust is 7.28 mN.Based on the simulation optimization,the limitation of the dual-stage grid is discussed.The grid performs well under high voltage conditions(>3000 V)but not well under low voltage conditions(<2000 V).Finally,since argon is cheaper and more advantageous in future engineering applications,the plasma distribution and grid extraction ability under xenon and argon are analyzed and compared to study the flexibility of the dual-stage grid ion thruster.The simulation results show that a set of optimal parameters is only applicable to the corresponding propellant,which needs to be optimized for different propellant types.

Dual-Stage Hybrid Learning Particle Swarm Optimization Algorithm for Global Optimization Problems

Particle swarm optimization(PSO)is a type of swarm intelligence algorithm that is frequently used to resolve specific global optimization problems due to its rapid convergence and ease of operation.However,PSO still has certain deficiencies,such as a poor trade-off between exploration and exploitation and premature convergence.Hence,this paper proposes a dual-stage hybrid learning particle swarm optimization(DHLPSO).In the algorithm,the iterative process is partitioned into two stages.The learning strategy used at each stage emphasizes exploration and exploitation,respectively.In the first stage,to increase population variety,a Manhattan distance based learning strategy is proposed.In this strategy,each particle chooses the furthest Manhattan distance particle and a better particle for learning.In the second stage,an excellent example learning strategy is adopted to perform local optimization operations on the population,in which each particle learns from the global optimal particle and a better particle.Utilizing the Gaussian mutation strategy,the algorithm’s searchability in particular multimodal functions is significantly enhanced.On benchmark functions from CEC 2013,DHLPSO is evaluated alongside other PSO variants already in existence.The comparison results clearly demonstrate that,compared to other cutting-edge PSO variations,DHLPSO implements highly competitive performance in handling global optimization problems.

An adjustable anti-resonance frequency controller for a dual-stage actuation semi-active vibration isolation system

In the semiconductor manufacturing industry,the dynamic model of a controlled object is usually obtained from a frequency sweeping method before motion control.However,the existing isolators cannot properly isolate the disturbance of the inertial force on the platform base during frequency sweeping(the frequency is between 0 Hz and the natural frequency).In this paper,an adjustable anti-resonance frequency controller for a dual-stage actuation semi-active vibration isolation system(DSASAVIS)is proposed.This system has a significant anti-resonance characteristic;that is,the vibration amplitude can drop to nearly zero at a particular frequency,which is called the anti-resonance frequency.The proposed controller is designed to add an adjustable anti-resonance frequency to fully use this unique anti-resonance characteristic.Experimental results show that the closed-loop transmissibility is less than−15 dB from 0 Hz to the initial anti-resonance frequency.Furthermore,it is less than−30 dB around an added anti-resonance frequency which can be adjusted from 0 Hz to the initial anti-resonance frequency by changing the parameters of the proposed controller.With the proposed controller,the disturbance amplitude of the payload decays from 4 to 0.5 mm/s with a reduction of 87.5%for the impulse disturbance applied to the platform base.Simultaneously,the system can adjust the anti-resonance frequency point in real time by tracking the frequency sweeping disturbances,and a good vibration isolation performance is achieved.This indicates that the DSA-SAVIS and the proposed controller can be applied in the guarantee of an ultra-low vibration environment,especially at frequency sweeping in the semiconductor manufacturing industry.

Dual-stage constructed random graph algorithm to generate random graphs featuring the same topological characteristics with power grids

It is a common practice to simulate some historical or test systems to validate the efficiency of new methods or concepts. However, there are only a small number of existing power system test cases, and validation and evaluation results, obtained using such a limited number of test cases, may not be deemed sufficient or convincing. In order to provide more available test cases, a new random graph generation algorithm, named ‘‘dualstage constructed random graph’’ algorithm, is proposed to effectively model the power grid topology. The algorithm generates a spanning tree to guarantee the connectivity of random graphs and is capable of controlling the number of lines precisely. No matter how much the average degree is,whether sparse or not, random graphs can be quickly formed to satisfy the requirements. An approach is developed to generate random graphs with prescribed numbers of connected components, in order to simulate the power grid topology under fault conditions. Our experimental study on several realistic power grid topologies proves that the proposed algorithm can quickly generate a large number of random graphs with the topology characteristics of real-world power grid.

双源双能量CT碘值测定在胃癌术前T分期诊断中的价值

目的探讨双源双能量CT碘值测定在胃癌术前T分期诊断中的应用价值。方法选取2022年4—5月在福建省立医院放射科接受双源双能量CT,后经手术病理诊断确诊为T分期的138例胃癌患者。患者均采用双源双能量CT检查。比较T_(1)期、T_(2~3)期患者动脉期、静脉期正常胃壁、胃壁内层、胃壁外层碘含量,比较40、60、120 keV时影像学图像质量主观指标与客观指标。结果T_(1)期、T_(2~3)期患者动脉期、静脉期胃壁内层与胃壁外层碘含量比较,差异有统计学意义(P<0.001);胃壁内层与正常胃壁碘含量比较,差异有统计学意义(P<0.001);胃壁外层与正常胃壁碘含量比较,差异无统计学意义(P=0.130、0.262、0.231、0.022)。60 keV[(3.28±0.38)分]时总体图像质量评分高于40、120 keV[(3.01±0.43)、(3.14±0.41)分],差异有统计学意义(P<0.001,P=0.004);40 keV与60 keV、40 keV与120 keV、60 keV与120 keV病灶显著性评分比较,差异均无统计学意义(P=0.129、0.054、0.713)。40keV时CT值、图像噪声、信噪比(signal-noise ratio,SNR)、对比度噪声比(clinical nursing research,CNR)高于60、120keV时,60 keV时CT值、图像噪声、SNR、CNR高于120keV时,差异有统计学意义(P<0.001)。结论采用双源双能量CT碘值测定方式,对于鉴别诊断T_(1)期、T_(2~3)期胃癌具有一定价值,且能够提高图像的质量,对于提高胃癌术前T分期的准确率有重要意义。

面向高维多目标优化的双阶段双种群进化算法

随着目标维度的上升,高维多目标优化问题的帕累托前沿越来越复杂,传统的基于分解的高维多目标进化算法难以挑选出多样性和收敛性良好的种群。针对以上问题提出了一种面向高维多目标优化的双阶段双种群进化算法。该算法将进化过程划分为两个阶段,在第一阶段判断帕累托前沿的形状是否规则,而在第二阶段则根据帕累前沿的形状选择是否对权重向量进行调整,以保证种群在规则及不规则帕累托前沿上都能获得良好的多样性。为了对权重向量进行调整且不影响算法的收敛性,该算法使用了两个种群进行进化,一个主种群正常进化,另一个辅种群作为权重向量。为了在不规则的帕累托前沿上获得一组适应种群分布的权重向量,引入了自然界中能量平衡的概念收集了多样性良好的辅种群作为权重向量。将提出的算法与其他算法在3-10目标的测试问题上进行比较。实验结果表明,提出的算法在大多数测试问题上性能优于比较的算法。

平均载荷系数0.5一级的双模式压气机设计研究与验证

为全面提升压气机的研制能力,本文对平均载荷系数0.5一级的带单双外涵两种模式(双模式)核心驱动风扇的四级压气机开展了设计技术研究与验证。针对其平均级载荷系数高、两个模式性能变化大等特点,开展了双模式高负荷压气机设计、低损失大流量范围导叶设计以及低损失大攻角范围可调静子设计等技术研究工作,并在此基础上完成双模式核心驱动风扇与四级压气机的设计,开展0.8~1.0相对转速的三维特性分析,全面研究单双外涵两种模式下各级的匹配情况。试验结果表明:单双外涵两种模式下,压气机流量、压比、效率达到设计指标。单外涵模式1.0相对转速,最高效率0.874,双外涵模式0.924相对转速,最高效率0.87,两种模式下压气机流量调节范围达到31.4%。各级匹配良好,突破了双模式核心驱动风扇与压气机一体化匹配设计和平均载荷系数0.5一级的高负荷压缩部件设计等关键技术,为下一代发动机的核心压缩部件设计奠定了基础。

基于深度学习的木材缺陷智能检测的研究进展与展望

木材作为天然生物材料很容易受到内外界影响从而产生不符合人们生产需求的缺陷,人们为了准确高效的识别木材缺陷进行了大量的研究。本文对近年来基于深度学习的木材缺陷检测技术进行梳理,根据使用方法的侧重点不同将其分类,并针对典型方法加以细分归类和对比分析,总结了每种方法的优缺点及其应用面。此外,提出了基于深度学习的木材缺陷检测技术目前所存在的难点与所陷困境。

双涡控径向分级燃烧室流场特性

针对新设计的一种双涡控径向分级燃烧室流场特性,采用粒子图像测速仪试验的方式,获得不同压降(1.5%~5.5%)下该型燃烧室不同展向截面和流向截面上流场结构、流线、流速分布和回流区特性。试验结果表明,燃烧室在凹腔内形成了耦合展向涡与流向涡的三维涡系;主燃级旋流器后外旋螺旋流场与中心回流区共同构成三维涡球结构;凹腔与主燃级流场在主燃孔进气作用下相互耦合。随着压降变化,燃烧室冷态流场存在2种流态,压降小于3.5%时,旋流器旋转气流明显强于凹腔气流,凹腔气流被压至外壁流出,与主流掺混较为困难,在火焰筒下游与主流相互作用;压降大于3.5%时,旋流器旋转气流减弱,凹腔气流一同与旋转气流流出并相互作用,凹腔气流往主流掺混相对较为容易。

基于双级主动式拓扑的锂电池寿命优化

随着储能充电站的应用需求逐渐上升,锂电池作为主要储能载体应用广泛.但在大功率且频繁充放电工况下,锂电池循环寿命会显著降低,导致储能成本升高.鉴于超级电容具有长寿命优势,构造由超级电容与锂电池组成的混合储能系统,通过优化控制策略提高锂电池寿命并降低储能充电站的投运成本.提出双级主动式拓扑的混合储能系统,由锂电池为两个超级电容模组交替充电,再通过超级电容模组高倍率放电.基于此,根据充电桩工况提出多阶段功率状态估计协同规划策略,通过优化功率分配方案来平缓锂电池功率波动,从而保护锂电池.仿真结果表明:相较于纯锂电池储能和传统全主动式拓扑储能,双级主动式拓扑储能方案显著提高了锂电池循环寿命.

双级深床过滤方式对铝液排杂净化能力的影响

针对大深床单级过滤铝液的净化效果不佳因而无法满足罐料、箔材、电子产品用材的质量要求的问题,采用小深床过滤结合大深床过滤的双级过滤方式,应用光学显微镜和扫描电镜等分析测试技术研究其过滤净化效果。结果表明:采用小深床过滤与大深床过滤相结合的双级过滤方式,过滤后小深床出口处夹杂含量均小于0.03 mm^(2)/kg,小深床有效起到粗过滤的作用,有效减轻大深床过滤夹杂的累积释放现象;经小深床过滤结合大深床过滤的双级过滤的铝液夹杂含量明显降低,过滤精度提高,有利于产品质量的稳定及提升;小深床的添加不会因铝液静态时间的延长影响细化剂的活性,对钛的衰减仅是0.00079%,铸锭的晶粒度稳定,显微疏松在铸锭中的分布长度幅度小、质量稳定。

两阶段轧制变形与时效下超细铁素体/马氏体双相钢的微观组织演变

对含铜低合金高强钢进行了两阶段轧制变形及时效处理,形成了超细晶铁素体/马氏体双相组织。利用扫描电子显微镜与电子背散射衍射技术分析了不同工艺下双相钢的微观组织演变规律,结合力学性能测试讨论了细晶强化与纳米相析出的协同强化增韧机理。结果表明,经过上述变形和时效处理,得到具有良好的强塑性结合的超细晶铁素体/马氏体双相钢,其晶粒平均尺寸为1.23μm。随着时效时间延长,细小的第二相弥散析出并均匀分布,使得实验钢的屈服强度提高。

双旋流燃烧室冷态流场2维湍流特性试验

为研究燃烧室流场湍流结构特性,采用粒子图像测速仪(PIV)对双级旋流器燃烧室流场进行测量,得到了不同进气速度下的速度场分布、雷诺应力分布和湍流度分布。结果表明:随着进气速度的提高,旋流器出口射流速度提高,中心回流区轴向速度变化较小;在2维平面上,燃烧室轴向测量截面出现5个高雷诺应力区域,分别为中心回流区外、中心回流区与高速旋转射流交汇区(剪切层)2处以及高速旋转射流与燃烧室头部模拟壁面接触区2处;回流区与高速旋转射流交汇区较高的雷诺应力分布有利于燃料与空气充分混合;湍流度分布与速度波动幅值和平均流速有关,中心回流区与高速旋转射流交汇区处湍流度较高。

宽温域工况下热泵技术应用的研究进展

为了研究实际运行中环境温度过低或目标供热温度较高工况下,热泵系统的性能系数及压缩机的可靠性,单级压缩循环已经不能满足供热需求。本文梳理了宽温域工况下热泵系统的应用现状,从补气增焓、双级压缩、复叠系统等技术分析了影响其系统能效的因素,相应热泵系统制热量较单级压缩系统可相对提高12%~15%。展望了宽温域工况下热泵技术的发展趋势与研究重点,对热泵技术进一步推广应用具有一定实际意义。