The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with ...The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.展开更多
Roll coating is a vital industrial process used in printing,packaging,and polymer film production,where maintaining a uniform coating is critical for product quality and efficiency.This work models non-isothermal Carr...Roll coating is a vital industrial process used in printing,packaging,and polymer film production,where maintaining a uniform coating is critical for product quality and efficiency.This work models non-isothermal Carreau fluid flow between a rotating roll and a stationary wall under fixed boundary constraints to evaluate how non-Newtonian and thermal effects influence coating performance.The governing equations are transformed into non-dimensional form and simplified using lubrication approximation theory.Approximate analytical solutions are obtained via the perturbation technique,while numerical results are computed using both the finite difference method and the BVPMidrich technique.Furthermore,Response surface methodology(RSM)is employed for optimization and sensitivity analysis.Analytical and numerical results show strong agreement(<1%deviation).The model predicts coating thickness 0.55≤λ≤0.64,power input 1.05≤P_(w)≤1.99,and separation force 0.91≤S_(f)≤1.82 for 0.1≤We≤0.9 and 0.01≤F≤0.09.Increasing We enhances the coating thickness and power input but reduces velocity and separation force.The findings provide physical insight into elastic and viscous effects in roll coating,providing insight for optimizing coating uniformity,minimizing wear,improving industrial coating processes,and extending substrate lifespan.展开更多
本文基于系统理论过程分析(STPA,system theoretic process analysis)方法,识别确定了飞机起落架收放系统的系统级危险,构建了系统的人机控制、系统功能动作和反馈等运行全过程的行为原理框图模型,识别系统运行过程中的不安全控制行为(U...本文基于系统理论过程分析(STPA,system theoretic process analysis)方法,识别确定了飞机起落架收放系统的系统级危险,构建了系统的人机控制、系统功能动作和反馈等运行全过程的行为原理框图模型,识别系统运行过程中的不安全控制行为(UCA,unsafe control action)并分析导致UCA发生的风险因素。研究表明,该方法不仅能够分析出传统安全分析方法识别到的所有组件物理故障因素,还能识别出位置作动控制组件(PACU,position and actuate on control unit)核心处理器算法延迟、机组成员误操作等由人机交互导致UCA发生的风险因素。本文研究结果可为民用飞机研发和使用全过程的安全性分析提供理论依据和方法支持。展开更多
A quantum time-dependent spectrum analysis, or simply, quantum spectral analysis (QSA) is presented in this work, and it’s based on Schrödinger’s equation. In the classical world, it is named frequency in t...A quantum time-dependent spectrum analysis, or simply, quantum spectral analysis (QSA) is presented in this work, and it’s based on Schrödinger’s equation. In the classical world, it is named frequency in time (FIT), which is used here as a complement of the traditional frequency-dependent spectral analysis based on Fourier theory. Besides, FIT is a metric which assesses the impact of the flanks of a signal on its frequency spectrum, not taken into account by Fourier theory and lets alone in real time. Even more, and unlike all derived tools from Fourier Theory (i.e., continuous, discrete, fast, short-time, fractional and quantum Fourier Transform, as well as, Gabor) FIT has the following advantages, among others: 1) compact support with excellent energy output treatment, 2) low computational cost, O(N) for signals and O(N2) for images, 3) it does not have phase uncertainties (i.e., indeterminate phase for a magnitude = 0) as in the case of Discrete and Fast Fourier Transform (DFT, FFT, respectively). Finally, we can apply QSA to a quantum signal, that is, to a qubit stream in order to analyze it spectrally.展开更多
通过系统理论过程分析(system-theoretic process analysis,STPA)方法识别航空事故危险因素,属于定性分析过程,无法定量地评估各因素对事故的影响程度。针对上述问题,提出STPA与贝叶斯网络(Bayesian network,BN)结合的定性与定量分析方...通过系统理论过程分析(system-theoretic process analysis,STPA)方法识别航空事故危险因素,属于定性分析过程,无法定量地评估各因素对事故的影响程度。针对上述问题,提出STPA与贝叶斯网络(Bayesian network,BN)结合的定性与定量分析方法。以捷蓝航空A320飞机襟翼事故为例,通过STPA方法构建了襟翼控制系统的控制结构模型并全面地分析了潜在的不安全控制行为及相关致因场景。随后将STPA定性分析结果转化为可定量分析的贝叶斯网络模型,从而识别出事故中的内部交互逻辑以及影响度较高的致因因素,提出全面的安全性建议。分析结果表明:导致事故的主要因素为液压源故障,而动力传输组件(power transmission unit,PTU)故障和液压管路泄漏是导致液压源失效的主要原因,关键重要度分别为0.688和0.299。展开更多
平视显示(Head-up Display,HUD)系统属于航电安全关键系统,可以提高低能见度下的飞机运行安全,需要在系统研制过程中开展完善的风险识别与分析。随着系统复杂性的增加,传统方法很难捕获系统组件交互带来的危险。为此,采用系统理论过程分...平视显示(Head-up Display,HUD)系统属于航电安全关键系统,可以提高低能见度下的飞机运行安全,需要在系统研制过程中开展完善的风险识别与分析。随着系统复杂性的增加,传统方法很难捕获系统组件交互带来的危险。为此,采用系统理论过程分析(Systematic Theory Process Analysis,STPA)对HUD进行分析,充分考虑系统的多方交互,识别系统潜在的不安全控制行为,同时利用时间自动机理论及其工具UPPAAL对系统进行建模,验证STPA识别的不安全控制行为;最后设计了一个路径算法,对导致其发生的危险路径进行检索。结果表明,该方法能够识别出系统潜在的危险及其原因,减少了人为因素对分析的影响。展开更多
文摘The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.
基金supported by the Talent Project of Tianchi Young-Doctoral Program in Xinjiang Uygur Autonomous Region of China(No.51052401510)Natural Science Foundation General Project(Grant Number 2025D01C36)of the Xinjiang Uyghur Autonomous Region of China+1 种基金This study received financial support from the National Natural Science Foundation of Xinjiang Province(Grant Nos.2022TSYCTD0019 and 2022D01D32)the China Scholarship Council(CSC)(Grant No.2021SLJ009915).
文摘Roll coating is a vital industrial process used in printing,packaging,and polymer film production,where maintaining a uniform coating is critical for product quality and efficiency.This work models non-isothermal Carreau fluid flow between a rotating roll and a stationary wall under fixed boundary constraints to evaluate how non-Newtonian and thermal effects influence coating performance.The governing equations are transformed into non-dimensional form and simplified using lubrication approximation theory.Approximate analytical solutions are obtained via the perturbation technique,while numerical results are computed using both the finite difference method and the BVPMidrich technique.Furthermore,Response surface methodology(RSM)is employed for optimization and sensitivity analysis.Analytical and numerical results show strong agreement(<1%deviation).The model predicts coating thickness 0.55≤λ≤0.64,power input 1.05≤P_(w)≤1.99,and separation force 0.91≤S_(f)≤1.82 for 0.1≤We≤0.9 and 0.01≤F≤0.09.Increasing We enhances the coating thickness and power input but reduces velocity and separation force.The findings provide physical insight into elastic and viscous effects in roll coating,providing insight for optimizing coating uniformity,minimizing wear,improving industrial coating processes,and extending substrate lifespan.
文摘本文基于系统理论过程分析(STPA,system theoretic process analysis)方法,识别确定了飞机起落架收放系统的系统级危险,构建了系统的人机控制、系统功能动作和反馈等运行全过程的行为原理框图模型,识别系统运行过程中的不安全控制行为(UCA,unsafe control action)并分析导致UCA发生的风险因素。研究表明,该方法不仅能够分析出传统安全分析方法识别到的所有组件物理故障因素,还能识别出位置作动控制组件(PACU,position and actuate on control unit)核心处理器算法延迟、机组成员误操作等由人机交互导致UCA发生的风险因素。本文研究结果可为民用飞机研发和使用全过程的安全性分析提供理论依据和方法支持。
文摘A quantum time-dependent spectrum analysis, or simply, quantum spectral analysis (QSA) is presented in this work, and it’s based on Schrödinger’s equation. In the classical world, it is named frequency in time (FIT), which is used here as a complement of the traditional frequency-dependent spectral analysis based on Fourier theory. Besides, FIT is a metric which assesses the impact of the flanks of a signal on its frequency spectrum, not taken into account by Fourier theory and lets alone in real time. Even more, and unlike all derived tools from Fourier Theory (i.e., continuous, discrete, fast, short-time, fractional and quantum Fourier Transform, as well as, Gabor) FIT has the following advantages, among others: 1) compact support with excellent energy output treatment, 2) low computational cost, O(N) for signals and O(N2) for images, 3) it does not have phase uncertainties (i.e., indeterminate phase for a magnitude = 0) as in the case of Discrete and Fast Fourier Transform (DFT, FFT, respectively). Finally, we can apply QSA to a quantum signal, that is, to a qubit stream in order to analyze it spectrally.
文摘平视显示(Head-up Display,HUD)系统属于航电安全关键系统,可以提高低能见度下的飞机运行安全,需要在系统研制过程中开展完善的风险识别与分析。随着系统复杂性的增加,传统方法很难捕获系统组件交互带来的危险。为此,采用系统理论过程分析(Systematic Theory Process Analysis,STPA)对HUD进行分析,充分考虑系统的多方交互,识别系统潜在的不安全控制行为,同时利用时间自动机理论及其工具UPPAAL对系统进行建模,验证STPA识别的不安全控制行为;最后设计了一个路径算法,对导致其发生的危险路径进行检索。结果表明,该方法能够识别出系统潜在的危险及其原因,减少了人为因素对分析的影响。
