飞行员人因可靠性定量预测

为有效预测飞行员的人因可靠性,以保障飞行安全,基于认知可靠性与失误分析法(CREAM)的扩展法,建立飞行员人因可靠性定量预测模型。依据飞行员的任务特点,调整认知行为及认知功能。通过优化共同绩效条件(CPC)因子水平等级,并增加新的因子,改进CPC因子依赖规则,用于修正因子的初始评估结果,解决扩展法未考虑因子间关系的问题,从而完成模型的建立。利用回看分析法验证模型的有效性,采用所建立的模型和扩展法分别对已发生的飞行案例进行预测,并与实际发生结果对比分析。结果表明,与扩展法相比,采用飞行员定量预测模型得到的预测结果与案例发生结果所反映的控制模式更为匹配。     

基坑放坡开挖对下方既有地铁隧道影响计算及风险预测

为研究基坑放坡开挖对下方既有地铁隧道的影响以及预测隧道结构的风险,通过改进的计算方法得到放坡开挖基坑引起下方既有地铁隧道的竖向和横向附加荷载、位移、相对变形曲率共6个隧道结构安全的物理表现因子;将位移计算结果与前人理论计算结果、实测数据对比验证,并分析各土层物理力学参数对6个因子的敏感性;最后,基于正态分布概率模型对较敏感的土层物理力学参数随机取值,利用蒙特卡罗方法计算6个因子各级风险发生的概率和竖向、横向2类因子综合影响下隧道结构各级风险发生的总概率。研究结果表明:与原来仅限于矩形开挖基坑的计算方法相比,改进后的计算方法适用范围更广、实用性更强;在算例二分析中,隧道竖向位移和相对变形曲率超过控制值的概率分别为12%和68.7%,其余因子均为0,隧道竖向相对变形曲率是隧道结构处于不安全状态的最主要因子;若不采取预防措施,隧道结构将有高达73.27%的概率处于不安全状态,其中有68.7%的概率处于很不安全状态。     

RBF神经网络可靠度分析方法在边坡稳定性研究中的应用

针对边坡稳定性可靠度分析,当状态函数无法显式表达且传统计算方法求解复杂问题困难时,提出一种基于ABAQUS和粒子群优化径向基函数神经网络的可靠度分析方法。基于ABAQUS的强度折减方法计算所选随机变量对应的安全系数,利用径向基函数神经网络的数据拟合功能,建立模型并映射出安全系数和随机变量之间的关系,构造响应面功能函数;利用蒙特卡罗生成的大量随机样本代入功能函数得到相应的安全系数,进而计算边坡的失稳概率和可靠度指标来反映边坡稳定性。研究结果表明:相对于传统方法,本文方法计算效率更高、误差更小,适合实际工程应用。     

基于模糊评价的VDT系统搜索策略绩效形成机理研究

为优化视觉显示终端（VDT）结构性搜索界面的布局,提高作业绩效和安全,设计了VDT系统搜索实验,构建了搜索目标位置在4个主观偏好指标下的Pythagorean模糊集决策矩阵,运用交互式多准则决策（TODIM）法计算各目标位置偏好的总体优势度并排序;同时对VDT系统搜索实验中各目标位置的绩效进行方差分析并排序,分析系统搜索策略下作业者对目标位置的主观偏好与绩效之间的关系。研究结果表明:基于系统搜索策略的VDT作业绩效在不同目标位置差异显著;导致绩效差异的根本原因是作业者对搜索目标位置的主观偏好度,而不是搜索目标的位置属性;除中心区域外,偏好度高的区域搜索绩效要优于偏好度低的区域。     

基于热湿交换理论的巷道风流温、湿度影响因素研究

为了研究巷道风流参数的影响因素、预测风流温湿度的变化规律,结合热湿交换理论,建立了风流与围岩壁面之间热湿交换的数学模型,以及贴体坐标系下围岩内部温度场的导热微分方程;利用数值方法,将围岩内部的导热问题与影响风流参数变化的热湿交换问题耦合起来,并以大柳塔煤矿52505综采工作面为例进行计算,得到了与实测参数较为一致的模拟结果,验证了该数值方法的有效性。研究结果表明:风流温度受原始岩温、入风流温度、局部热源强度等因素的影响,风流相对湿度与入风流温、湿度以及井下湿源的数量和强度有关;巷道壁温作为将围岩温度场与风流参数之间关联起来的主要因素,对模拟结果影响较大,其数值取决于壁面与风流之间热湿交换以及围岩原始岩温。     

顶板含水层防水试验的钻孔单位涌水量计算方法

为了实现利用井下放水试验获取顶板含水层的钻孔单位涌水量,采用抽水试验中的地下水动力学计算公式,结合观测孔的水位降深,给出了放水孔水位降深的计算方法;利用观测孔水位降深和观测孔与放水孔之间距离的对数曲线图,提出了放水孔水位降深的图解法;对于承压含水层,基于钻孔单位涌水量与含水层渗透系数之间的线性相关关系,可以通过含水层的渗透系数获取钻孔单位涌水量;通过实例分析,解析法和图解法计算得到的放水孔单位涌水量相近,结合现场放水试验情况,分析了放水孔单位涌水量的可靠性,并对3种方法的适用条件进行了讨论。研究结果表明:利用放水试验获取的放水孔单位涌水量符合实际情况,可以作为含水层富水性评价和矿井水文地质条件分析的依据。     

司钻法自动化压井系统试验研究

自动化压井是指计算机能够按照一定的控制原则独立完成压井的1种方法。为了验证自动化压井系统的可行性和平稳性,开展了多种不同程度的试验井气侵模拟,利用自动化压井系统进行司钻法自动化压井操作试验,成功实施了司钻法第1循环周压井。研究结果表明:自动化压井系统能够实时获取和分析溢流参数,迅速准确生成压井施工单,对节流控制箱实施远程控制并完成节流阀开度的调整;在不同气侵程度下,自动化压井系统能够按照压井设计曲线将立压稳定控制在目标值附近;在气侵气体向上运移和排出井口的过程中,井底压力波动远小于人工压井所产生的压力波动。该项研究基本验证了自动化压井系统在钻井井场应用的可行性。     

爆破荷载作用下隧道中隔岩稳定性研究

为研究爆破动力荷载作用下隧道中隔岩稳定性评价标准,以福州地铁2号线为工程背景,结合强度折减动力分析法和数值模拟,同时考虑中隔岩塑性区贯通、位移超过规范值、计算不收敛3种判据,综合对隧道中隔岩进行动力安全系数分析,研究隧道不同净距、不同开挖进尺后行洞隧道爆破开挖对隧道整体安全系数的影响。研究结果表明:中隔岩塑性区贯通时特征点位移和规范中位移限值较为接近,可共同作为评价中隔岩稳定性的最终评价标准;隧道净距越大、进尺越小,隧道整体安全系数越高;对围岩质量较差且净距小于1.6 m的双线隧道进行爆破开挖时,建议将爆破进尺控制在2 m以内。研究结果可为类似工程提供理论参考依据。     

On the latent state estimation of nonlinear population dynamics using Bayesian and non-Bayesian state-space models

Nonlinear state-space models have been increasingly applied to study population dynamics and data assimilation in environmental sciences. State-space models can account for process error and measurement error simultaneously to correct for the bias in the estimates of system state and model parameters. However, few studies have compared the performance of different nonlinear state-space models for reconstructing the state of population dynamics from noisy time series. This study compared the performance of the extended Kalman filter (EKF), unscented Kalman filter (UKF) and Bayesian nonlinear state-space models (BNSSM) through simulations. Synthetic population time series were generated using the theta logistic model with known parameters, and normally distributed process and measurement errors were introduced using the Monte Carlo simulations. At higher levels of nonlinearity, the UKF and BNSSM had lower root mean square error (RMSE) than the EKF. The BNSSM performed reliably across all levels of nonlinearity, whereas increased levels of nonlinearity resulted in higher RMSE of the EKF. The Metropolis–Hastings algorithm within the Gibbs algorithm was used to fit the theta logistic model to synthetic time series to estimate model parameters. The estimated posterior distribution of the parameter θ indicated that the 95% credible intervals included the true values of θ (=0.5 and 1.5), but did not include 1.0 and 0.0. Future studies need to incorporate the adaptive Metropolis algorithm to estimate unknown model parameters for broad applications of Bayesian nonlinear state-space models in ecological studies.     

Concentrations of inorganic elements in bottled waters on the Swedish market

This study presents the concentrations of about 50 metals and ions in 33 different brands of bottled waters on the Swedish market. Ten of the brands showed calcium (Ca) concentrations ≤10 mg L⁻¹ and magnesium (Mg) levels <3 mg L⁻¹, implying very soft waters. Three of these waters had in addition low concentrations of sodium (Na; <7 mg L⁻¹), potassium (K; <3 mg L⁻¹) and bicarbonate (HCO₃ ≤31 mg L⁻¹). These brands were collected from barren districts. Nine of the brands were collected from limestone regions. They showed increased Ca-levels exceeding 50 mg L⁻¹ with a maximum of 289 mg L⁻¹. Corresponding Mg-levels were also raised in two brands exceeding 90 mg L⁻¹. Two soft and carbonated waters were supplemented with Na₂CO₃ and NaCl, resulting in high concentrations of Na (644 and 648 mg L⁻¹) and chloride (Cl; 204 and 219 mg L⁻¹). Such waters may make a substantial contribution to the daily intake of NaCl in high water consumers. The storage of carbonated drinking water in aluminum (Al) cans increased the Al-concentration to about 70 μg L⁻¹. Conclusion As there was a large variation in the material as regards concentrations of macro-elements such as Ca, Mg, Na, K and Cl. Supplementation with salts, e.g., Na₂CO₃, K₂ CO₃ and NaCl, can lead to increased concentrations of Na, K and Cl, as well as decreased ratios of Ca/Na and larger ratios of Na/K. Water with high concentrations of e.g., Ca and Mg, may make a substantial contribution to the daily intake of these elements in high water consumers. Al cans are less suited for storage of carbonated waters, as the lowered pH-values may dissolve Al. The levels of potentially toxic metals in the studied brands were generally low.