Active disturbance rejection control to MIMO nonlinear systems with stochastic uncertainties: approximate decoupling and output-feedback stabilisation

ABSTRACT

In this paper, we apply the active disturbance rejection control, an emerging control technology, to output-feedback stabilisation for a class of uncertain multi-input multi-output nonlinear systems with vast stochastic uncertainties. Two types of extended state observers (ESO) are designed to estimate both unmeasured states and stochastic total disturbance which includes unknown system dynamics, unknown stochastic inverse dynamics, external stochastic disturbance without requiring the statistical characteristics, uncertain nonlinear interactions between subsystems, and uncertainties caused by the deviation of control parameters from their nominal values. The estimations decouple approximately the system after cancelling stochastic total disturbance in the feedback loop. As a result, we are able to design an ESO-based stabilising output-feedback and prove the practical mean square stability for the closed-loop system with constant gain ESO and the asymptotic mean square stability with time-varying gain ESO, respectively. Some numerical simulations are presented to demonstrate the effectiveness of the proposed output-feedback control scheme.     

变分布的量子行为粒子群优化算法求解工程约束优化问题

针对工程形状设计领域中带有多个约束条件的非线性设计优化问题,提出了一种自适应的基于高斯分布的量子行为粒子群优化(AG-QPSO)算法。通过自适应地调整高斯分布,AG-QPSO算法能够在搜索的初始阶段有很强的全局搜索能力,随着搜索过程的进行,算法的局部搜索能力逐渐增强,从而满足了算法在搜索过程不同阶段的需要。为了验证算法的有效性,在压力容器和张弦设计问题这两个工程约束优化问题上进行50轮独立实验。实验结果表明,在满足所有约束条件的情况下,AG-QPSO算法在压力容器设计问题上取得了5890.9315的平均解和5885.3328的最优解,在张弦设计问题上取得了0.01096的平均解和0.01096的最优解,远优于标准粒子群优化(PSO)算法、具有量子行为的粒子群优化(QPSO)算法和高斯量子行为粒子群(G-QPSO)算法等现有的算法的结果,同时AG-QPSO算法取得的结果的方差较小,说明该算法具有很好的鲁棒性。     

Nb5+掺杂对(Ca0.97Ba0.03)Cu3Ti4O12陶瓷结构与电性能的影响

该文利用固相反应法制备了(Ca0.97Ba0.03)Cu3Ti4-xNbxO12 (x=0,0.01,0.03,0.05,0.07,0.10,0.15,0.20， 摩尔分数)陶瓷。借助X线衍射仪及扫描电子显微镜研究了Nb5+的摩尔分数对(Ca0.97Ba0.03)Cu3Ti4O12陶瓷的相结构及表面微观形貌的影响，借助高低温介电测试系统和阻抗测试仪获得了(Ca0.97Ba0.03)Cu3Ti4-xNbxO12陶瓷电性能变化规律。结果表明，各组分(Ca0.97Ba0.03)Cu3Ti4-xNbxO12陶瓷均为单相立方钙钛矿结构；Nb5+摩尔分数的增加可抑制(Ca0.97Ba0.03)Cu3Ti4-xNbxO12陶瓷晶粒的生长并消除其晶粒异常长大；适量掺杂 Nb+能够有效提高(Ca0.97Ba0.03)Cu3Ti4-xNbxO12陶瓷的晶界电阻，从而降低其介电损耗，且可提高(Ca0.97Ba0.03)Cu3Ti4-xNbxO12陶瓷相对介电常数的温度稳定性。     

压水堆堆芯损伤评价系统研究与开发

堆芯损伤评价是反应堆事故后应急评价的重要组成部分。本文在国外文献基础上,结合国内的运行经验,对压水堆堆芯损伤评价进行研究,并开发了相应的软件程序。堆芯损伤评价包括基于堆芯裸露时间、在线监测仪表读数和取样分析数据三种方法。考虑应急实时要求、电厂实际情况与国际经验,本文采用了基于在线监测仪表读数的评价方法,该方法主要是基于堆芯热电偶读数与安全壳辐射监测仪表读数进行评价,其他监测仪表读数进行辅助合理性证实。     

Quantitative relationship between time margin and human reliability

Operator reliability in complex systems is influenced by various performance shaping factors (PSFs). Time is a particularly important PSF; however, empirical studies of human reliability analysis (HRA) are rarely focused on modeling the effect of time PSF on human error probability (HEP). This study contributes to HRA literature by investigating the empirical relationship between time margin and HEP. Time margin is defined as the difference between the time available to complete a task and the time required to successfully complete the task, divided by the required time. We investigate and compare two models (logistic and linear) to explain HEP based on time margin. The empirical HEP data for model testing were extracted from a microworld simulator (Study 1) and a full-scope simulator (Study 2) in two existing studies relevant to procedural tasks in nuclear power plants. For Study 1, both models exhibited an acceptable, equivalent explanatory power; for Study 2, although both models exhibited an acceptable explanatory ability, the logistic model explained more variance in HEP. Our findings indicate the potential of the logistic model in explaining and predicting HEP based on time margin in time-critical tasks.     

Analyzing dissipation effects on the non-classicality witnessing by a qubit via the entangled state representation

ABSTRACT

In this paper, we study detection of the state non-classicality for a quantum harmonic oscillator by a qubit in the presence of dissipation effects. We show that dissipation can enhance the effectiveness of the method in case of using the corrected form of the related nonclassicality witness. Such an improvement is attributed to the fact that dissipation leads to probing a surface, instead of a curve, of the complex plane for non-classicality condition on normally-ordered characteristic function.     

PEO对固态锂电池正极/电解质界面的改性

在固态锂电池正极/氧化物电解质界面处引入聚氧化乙烯(PEO)缓冲层以改善固体接触。首先,用热压烧结法制备了密度为5.25 g·cm-3、锂离子电导率为8.33×10-4S·cm-4的Li6.4La3Zr1.4Ta0.6O12(LLZTO)固体电解质。其次,配制了PEO-LiTFSI-LLZTO缓冲层和LiFePO4复合正极浆料,用匀胶机旋涂法将PEO缓冲层和复合正极浆料依次涂覆在电解质表面,加热加压后显著改善界面接触,测得60℃下正极界面电阻值为509Ω·cm2。测试对称电池充/放电曲线证明界面稳定性良好,电池首次循环放电容量145.8 mAh·g-1,库伦效率大于97%。     

Entropic Contributions to Protein Stability

Thermodynamic stability is an important property of proteins that is linked to many of the trade-offs that characterize a protein molecule and therefore its function. Designing a protein with a desired stability is a complicated task given the intrinsic trade-off between enthalpy and entropy which applies for both the folded and unfolded states. Traditionally, protein stability is manipulated by point mutations which regulate the folded state enthalpy. In some cases, the entropy of the unfolded state has also been manipulated by means that drastically restrict its conformational dynamics such as engineering disulfide bonds. In this mini-review, we survey various approaches to modify protein stability by manipulating the entropy of either the unfolded or the folded states. We show that point mutations that involve elimination of long-range contacts may have a greater destabilization effect than mutations that eliminate shorter-range contacts. Protein conjugation can also affect the entropy of the unfolded state and thus the overall stability. In addition, we show that entropy can contribute to shape the folded state and yield greater protein stabilization. Hence, we argue that the entropy component can be practically manipulated both in the folded and unfolded state to modify protein stability.     

几种多态含能材料构型转变的DFT研究

为了从分子层面上对含能材料不同分子构型间的转变情况有一个直观认识,借助Gaussian 09软件,运用密度泛函理论(DFT),采用TS算法搜寻β-RDX→α-RDX、γ-HMX→β-HMX、ε-CL-20→β-CL-20及β-FOX-7→α-FOX-7在分子构型转变过程中的过渡态结构,确定了它们的构型转变过程;并通过计算吉布斯自由能随构型转变路径的变化,比较多态含能材料分子构型转变的难易程度。结果表明,由亚稳晶型到稳定晶型的转变首先会越过过渡态,克服自由能能垒转变为亚稳态结构,实现β-RDX→α-RDX、γ-HMX→β-HMX、ε-CL-20→β-CL-20及β-FOX-7→α-FOX-7分子构型转变分别需要克服的自由能能垒分别为5.25、22.21、9.69和10.24kJ/mol。因此,常温常压下β-RDX→α-RDX、γ-HMX→β-HMX、ε-CL-20→β-CL-20及β-FOX-7→α-FOX-7构型转变的难度大小排序为:HMX>>FOX-7>CL-20>RDX。     

Multi-task learning for video anomaly detection

We propose a multi-task learning framework for video anomaly detection based on a novel pipeline. Our model contains two crossing streams, one stream employs the backbone of Attention-R2U-net for future frame prediction, while the other is designed based on an encoder–decoder network to reconstruct the input optical flow maps. In addition, the latent layers of the two streams are merged together and assigned with a Deep SVDD-based loss at each location individually. Through the combination of these three tasks, the two-stream-crossing pipeline can be trained end-to-end to provide a comprehensive evaluation for the anomaly targets. Experimental results on several popular benchmark datasets show that our model outperforms the state-of-the-art competing models, which can be applied to different types of anomalous targets and meanwhile achieves remarkable precision.