基于Bow-tie模型的大型水利工程施工临时用电风险分析

为研究大型水利工程施工临时用电风险控制要点,文章基于宁海县清溪水库工程实际,构建施工临时用电Bow-tie模型,选取触电作为顶上事件,针对4项主要原因和2项后果,从消除、预防、控制、削弱4个角度具体分析控制措施的优先级与有效性,从而确定关键控制措施与核心岗位。最后,从验收程序、统一标准、人员素质3个方面提出预防策略,为大型水利工程施工临时用电管理提供参考。

基于Bow-tie模型的民航安检员违规行为影响因素识别

安全是民航业的生命线,也是每一个民航人追求的目标,空防安全是民航安全中非常重要的组成部分,民航安检工作是保卫空防安全的最后一道防线,关系着国家和人民生命财产安全。民航安检员一旦在安检工作中稍有疏忽,就可能会造成影响飞行安全的严重后果。对大部分重大安全事故进行统计,可以发现人因事故所占比例可达70%以上。

基于Bow-Tie-LOPA的煤矿安全风险评估方法应用研究

为解决传统安全评估方法的局限性,有效降低煤矿安全事故、提升煤矿安全管理效能,提出基于Bow-Tie模型的LOPA煤矿安全风险评估方法,通过研究两种方法的概念并分析两种方法相结合的应用,综合应用Bow-Tie-LOPA方法进行煤矿安全风险评估,分析验证Bow-Tie-LOPA方法在煤矿安全风险评估中的可行性和有效性;利用Bow-Tie模型绘制煤矿安全风险事件因果链,找出可供LOPA方法分析的事故场景,并基于LOPA分析风险事件发生率和后果,利用风险矩阵和确定风险等级的方法,进一步评估事故场景,以确定煤矿安全风险后果以及安全保护措施。研究结果表明:LOPA方法的引入有利于Bow-Tie模型分析煤矿复杂事故和危机情境,提高煤矿安全风险管理水平。

基于STPA和Bow-Tie模型的地面无人平台系统安全分析方法

随着地面无人平台(Unmanned Ground Vehicles,UGVs)在复杂作业环境中的潜在应用和战略价值日益凸显,确保其自主行为的安全性变得至关重要。提出一种结合系统理论过程分析(System-Theoretic Process Analysis,STPA)和Bow-Tie模型的地面无人平台系统安全分析方法。围绕遥控操作地面无人平台系统安全,通过STPA方法识别UGV系统中的不安全控制行为及其潜在风险,并利用Bow-Tie模型分析从损失致因场景到可能事故后果的事件链,得到风险传播路径和风险扩散路径。最终,基于Bow-Tie分析结果确定主被动安全分级控制措施,并通过自主安全控制器实现了系统安全管理。

基于Ansys/Bow-Tie燃气泄漏的双向风险分析

燃气泄漏事故伴随着爆炸、中毒等多项风险威胁,造成经济损失和伤亡损失。利用Ansys/Bow-Tie建立扩散模型与分析计算模型,将燃气泄漏定性与定量分析。研究表明:在定性变化中,燃气泄漏后泄漏区域的燃气扩散速度呈指数大模块式上升,扩散速度极快;在定量变化中,燃气泄漏的主要风险来源于巡检不足以及检维修不及时可能发生的概率最大,分别为0.039和0.046,通过加装有毒有害气体仪表报警监测群和对大风险问题加强监控可为风险管控提供帮助。

Bow-tie技术在CCUS项目注入系统的应用

二氧化碳捕集、利用与封存(CCUS)技术是实现化石能源低碳化利用的重要技术手段。但CCUS全流程存在二氧化碳泄漏、冻伤、窒息以及物体打击等风险,特别是注入系统涉及高压、低温及二氧化碳多相态变化等,易造成二氧化碳腐蚀、泄漏。通过Bow-tie技术对某CCUS项目注入系统开展风险识别、分析和控制,重点对设备设施及作业活动危害因素分析并制定有效管控措施,研究结果可为CCUS注入系统长期安全平稳高效运行提供技术支持。

基于4R和屏障理论的煤矿职业健康安全Bow-Tie模型构建

为减少煤矿作业人员健康安全事故,降低安全事故风险,依据4R危机理论和屏障理论,设置了预防性屏障和消减性屏障,增加事故的处置项,构建了煤矿职业健康安全Bow-Tie模型,以邯郸峰峰煤矿员工职业健康为例,构建安全风险分析和评价的Bow-Tie模型。研究表明:基于4R和屏障理论的煤矿职业健康安全的Bow-Tie模型具有处置危机功能,可以系统、直观地呈现事故成因、结果、预防及处置;缩减力和预备力设置的预防性屏障可以将事故的发生率降到最低,消减性屏障可以减缓事故的严重程度,若屏障同时失效,可启动反应力和恢复力的应急预案措施进行处置,进而有效避免事故造成的严重后果,并尽快恢复生产或活动水平;对峰峰煤矿作业人员健康安全事故进行Bow-Tie模型分析,验证了该模型的实用性,有效预防了煤矿职业健康安全事故,促进了煤矿职业健康安全管理水平和面对严重后果的应急管理水平提升。

飞机风挡裂纹/破裂类事件统计及Bow-tie模型分析

为分析航空器风挡裂纹/破裂类事件的安全风险,收集1 629份风挡裂纹/破裂类事件,对样本事件涉及故障状况、飞行阶段、故障原因等特征进行统计分析,确定风挡裂纹/破裂类事件的可能原因、潜在后果及其预防、减缓控制措施并绘制了风挡裂纹/破裂类事件Bow-tie模型图。结果表明:风挡损伤的主要情形包括裂开、裂缝、结冰、烟雾、划伤等;涉及风挡及相关部件故障以加温故障、雨刷故障为主;飞行阶段以巡航、爬升为主;风挡裂纹/破裂事件的主要原因为鸟击、零部件缺失/故障、系统失效/故障、冰击,最终有针对性地提出预防措施:机务、机组等相关人员应做好航前、航后检查;对零部件缺失/损坏/磨损、系统失效、鸟击等高发事件类型进行重点关注,提高机组人员对此类突发事件的应对能力等。

基于改进Bow-tie模型的煤矿瓦斯爆炸事故分析与研究

针对我国伤亡人数较多的采矿行业,对伤亡人数最多的瓦斯爆炸事故进行了分析,提出了改进Bow-tie模型。在原因辨识环节将瓦斯爆炸事故的原因归纳为人因、物因、环境、管理4个方面进行论述,利用屏障思维对主动屏障进行量化分级提出预防措施,通过模型分析事故可能产生的安全、经济、环境、社会后果,提出消减措施作为被动屏障,绘制改进Bow-tie图,并在此基础上运用层次分析进行评价分析。研究表明,管理体系欠缺以及人的不安全行为是导致事故发生的主要因素。

基于Bow-Tie的复杂场景保护层分析方法研究

为解决复杂场景保护层分析中采用最大值法或加和法存在的问题,将Bow-Tie融入LOPA分析中,建立复杂场景的Bow-Tie计算模型。通过采用事故树分析方法,计算Bow-Tie模型中顶上事件发生的概率,确定预防类保护层及减缓类保护层的失效概率,给出了复杂场景事故发生概率合理的计算方法;通过计算Bow-Tie模型中事故树底事件的概率重要度和临界重要度,提出了判断复杂场景保护层重要度的方法。运用上述方法对某LNG储罐超压损坏的复杂场景进行了计算。研究表明,本方法能实现包含多重初始事件的复杂事故场景后果风险更合理的计算及保护层重要度的判定,从而为提高系统安全性及风险决策提供依据。

基于Bow-tie模型的大型水利工程高处坠落事故风险分析

为研究Bow-tie模型在大型水利工程高处坠落事故风险分析中的应用,文章以宁海县清溪水库工程为例,依次识别危险点、顶上事件、原因、后果、控制措施、失效因素和失效控制措施,并从控制措施角度进行分析,结合工程实际,从完善控制措施体系、运用智能化手段、提升一线人员素质3个方面提出应对策略,为类似工程预防高处坠落事故提供参考。

基于Bow-Tie模型和未确知测度理论的煤矿透水风险分析

为了克服煤矿井下透水事故安全性评价相关因子的不确定性,以及权重指标赋值模糊的问题,采用Bow-Tie模型分析法通过对煤矿井下的人、物、环境、管理4个方面的分析研究,建立出煤矿透水事故的Bow-Tie评价模型,把得到的12项透水事故的影响因子作为煤矿透水事故风险评估的评价指标。通过层次分析法对指标进行权重的赋值,最后由未确知测度法确定煤矿透水事故风险评价等级。通过对小回沟煤矿进行实例评估分析,评价结果与该煤矿实际相符合,可见该法的合理性和适用性,可以为煤矿透水事故的风险评价提出一些指导。

基于Bow-tie模型的化工企业污水池作业有害气体风险分析

化工企业污水池有限空间作业的事故时有发生,每年都有化工企业的员工在污水池作业时发生中毒、爆炸等事故。根据对往年事故及相关资料的分析,总结出了化工企业污水池有限空间作业事故发生的共性原因,并以化工企业污水池有限空间作业时工人暴露于高浓度有害气体中为顶上事件,通过设备因素、人为因素等6个中间事件和17个基本事件来构成事故树,使用Bow-tie模型对事故的发生条件和控制措施进行了分析,并提出了化工企业防止该类型事故的对策措施。

Insight Into the Separation-of-Variable Methods for the Closed-Form Solutions of Free Vibration of Rectangular Thin Plates

The separation-of-variable(SOV)methods,such as the improved SOV method,the variational SOV method,and the extended SOV method,have been proposed by the present authors and coworkers to obtain the closed-form analytical solutions for free vibration and eigenbuckling of rectangular plates and circular cylindrical shells.By taking the free vibration of rectangular thin plates as an example,this work presents the theoretical framework of the SOV methods in an instructive way,and the bisection–based solution procedures for a group of nonlinear eigenvalue equations.Besides,the explicit equations of nodal lines of the SOV methods are presented,and the relations of nodal line patterns and frequency orders are investigated.It is concluded that the highly accurate SOV methods have the same accuracy for all frequencies,the mode shapes about repeated frequencies can also be precisely captured,and the SOV methods do not have the problem of missing roots as well.

Estimation of Chloride Diffusivity in Hydrated Tricalcium Silicate Using a Hydration-Diffusion Integrated Method

This study aims to develop a chloride diffusion simulation method that considers the hydration microstructure and pore solution properties during the hydration of tricalcium silicate(C3S).The method combines the hydration simulation,thermodynamic calculation,and finite element analysis to examine the effects of pore solution,including effect of electrochemical potential,effect of chemical activity,and effect of mechanical interactions between ions,on the chloride effective diffusion coefficient of hydrated C3S paste.The results indicate that the effect of electrochemical potential on chloride diffusion becomes stronger with increasing hydration age due to the increase in the content of hydrated calcium silicate;as the hydration age increases,the effect of chemical activity on chloride diffusion weakens when the number of diffusible elements decreases;the effect of mechanical interactions between ions on chloride diffusion decreases with the increase of hydration age.

Structural Modal Parameter Recognition and Related Damage Identification Methods under Environmental Excitations: A Review

Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the structure.Therefore,it is particularly significant to identify the structural modal parameters according to the monitoring data information in the structural health monitoring(SHM)system,so as to provide a scientific basis for structural damage identification and dynamic model modification.In view of this,this paper reviews methods for identifying structural modal parameters under environmental excitation and briefly describes how to identify structural damages based on the derived modal parameters.The paper primarily introduces data-driven modal parameter recognition methods(e.g.,time-domain,frequency-domain,and time-frequency-domain methods,etc.),briefly describes damage identification methods based on the variations of modal parameters(e.g.,natural frequency,modal shapes,and curvature modal shapes,etc.)and modal validation methods(e.g.,Stability Diagram and Modal Assurance Criterion,etc.).The current status of the application of artificial intelligence(AI)methods in the direction of modal parameter recognition and damage identification is further discussed.Based on the pre-vious analysis,the main development trends of structural modal parameter recognition and damage identification methods are given to provide scientific references for the optimized design and functional upgrading of SHM systems.

Effects of spatial heterogeneity on pseudo-static stability of coal mine overburden dump slope,using random limit equilibrium and random finite element methods:A comparative study

Sudden and unforeseen seismic failures of coal mine overburden(OB)dump slopes interrupt mining operations,cause loss of lives and delay the production of coal.Consideration of the spatial heterogeneity of OB dump materials is imperative for an adequate evaluation of the seismic stability of OB dump slopes.In this study,pseudo-static seismic stability analyses are carried out for an OB dump slope by considering the material parameters obtained from an insitu field investigation.Spatial heterogeneity is simulated through use of the random finite element method(RFEM)and the random limit equilibrium method(RLEM)and a comparative study is presented.Combinations of horizontal and vertical spatial correlation lengths were considered for simulating isotropic and anisotropic random fields within the OB dump slope.Seismic performances of the slope have been reported through the probability of failure and reliability index.It was observed that the RLEM approach overestimates failure probability(P_(f))by considering seismic stability with spatial heterogeneity.The P_(f)was observed to increase with an increase in the coefficient of variation of friction angle of the dump materials.Further,it was inferred that the RLEM approach may not be adequately applicable for assessing the seismic stability of an OB dump slope for a horizontal seismic coefficient that is more than or equal to 0.1.

Design of Voltage Equalization Circuit and Control Method for Lithium-ion Battery Packs

The active equalization of lithium-ion batteries involves transferring energy from high-voltage cells to low-voltage cells,ensuring consistent voltage levels across the battery pack and maintaining safety.This paper presents a voltage balancing circuit and control method.First,a single capacitor method is used to design the circuit topology for energy transfer.Next,real-time voltage detection and control are employed to balance energy between cells.Finally,simulation and experimental results demonstrate the effectiveness of the proposed method,achieving balanced voltages of 3.97 V from initial voltages of 4.10,3.97,and 3.90 V.The proposed circuit is simple,reliable,and effectively prevents overcharge and overdischarge.

An Improved Local RBF Collocation Method for 3D Excavation Deformation Based on Direct Method and Mapping Technique

Since the plasticity of soil and the irregular shape of the excavation,the efficiency and stability of the traditional local radial basis function(RBF)collocation method(LRBFCM)are inadequate for analyzing three-dimensional(3D)deformation of deep excavation.In this work,the technique known as the direct method,where the local influence nodes are collocated on a straight line,is introduced to optimize the LRBFCM.The direct method can improve the accuracy of the partial derivative,reduce the size effect caused by the large length-width ratio,and weaken the influence of the shape parameters on the LRBFCM.The mapping technique is adopted to transform the physical coordinates of a quadratic-type block to normalized coordinates,in which the deformation problem can easily be solved using the direct method.The stability of the LRBFCM is further modified by considering the irregular shape of 3D excavation,which is divided into several quadratic-type blocks.The soil’s plasticity is described by the Drucker-Prager(D-P)model.The improved LRBFCM is integrated with the incremental method to analyze the plasticity.Five different examples,including strip excavations and circular excavations,are presented to validate the proposed approach’s efficiency.

Assessment of leachate-contaminated clays using experimental and artificial methods

The investigation of leachate-contaminated clay(LCC)is essential for landfill engineering assessment and achievement of sustainable development goals.Several static and dynamic laboratory tests,including unconfined compressive strength(UCS),California bearing ratio(CBR),and cyclic simple shear,are conducted.Cyclic simple shear experiments on LCCs were performed to evaluate the damping and shear modulus.The investigated factors are vertical load(VL),leachate content(LC),frequency(F),and shear strain(ShS)for LCC.Forensic-based investigation optimization(FBIO)and equilibrium optimizer algorithm(EOA)were utilized in addition to multiple types of ensemble models,including adaptive boosting(ADB),gradient boosting regression tree(GBRT),extreme gradient boosting(XGB) and random forest(RF).The comparison of the methods showed that GBRT-FBIO and XGB-EOA models outperformed other models for shear modulus and damping of LCC.The p-value less than 0.0001 shows the significance of the used models in the response surface methodology(RSM)method.