Dynamic characterization of tailing dam using fully coupled dynamic analysis with different boundary conditions-a case study

The seismic response analysis of a tailing dam is studied using a fully coupled effective stress approach in conjunction with an advanced multi yield surface plastic constitutive model for tailing material.Strain controlled static and cyclic triaxial tests were carried out to obtain the constitutive model for the tailing material.The tailing materials were collected from the Rampura Agucha tailing dam(Rajasthan State,India).A 2D nonlinear finite element(FE)model was then developed using different boundary conditions from the tailing embankment constructed using the downstream and upstream method of rising using OpenSees software.In first case,the model boundary was fixed in both the X and Y directions,and in the second case,viscous dashpots were introduced for both side and horizontal boundaries.The model was validated with experimental results on tailing material.Analyses were carried out considering five different earthquake motions,which were applied at the base.Comparisons of the different boundary conditions in terms of displacement flow vectors,pore pressure and stress-strain curves during shaking are presented.From the analysis,it was observed that the viscous boundary condition replicates the actual field conditions more accurately than the fixed boundary condition.In addition,it was found that the tailing embankment constructed by the downstream and upstream method of rising is not susceptible to liquefaction and lateral spreading for earthquake motions,even for a magnitude>5.5.

Hydraulic Fracture Parameter Inversion Method for Shale GasWells Based on Transient Pressure-Drop Analysis during Hydraulic Fracturing Shut-in Period

Horizontal well drilling and multi-stage hydraulic fracturing are key technologies for the development of shale gas reservoirs.Instantaneous acquisition of hydraulic fracture parameters is crucial for evaluating fracturing effectiveness,optimizing processes,and predicting gas productivity.This paper establishes a transient flow model for shale gas wells based on the boundary element method,achieving the characterization of stimulated reservoir volume for a single stage.By integrating pressure monitoring data following the pumping shut-in period of hydraulic fracturing for well testing interpretation,a workflow for inverting fracture parameters of shale gas wells is established.This new method eliminates the need for prolonged production testing and can interpret parameters of individual hydraulic fracture segments,offering significant advantages over the conventional pressure transient analysismethod.The practical application of thismethodology was conducted on 10 shale gaswellswithin the Changning shale gas block of Sichuan,China.The results show a high correlation between the interpreted single-stage total length and surface area of hydraulic fractures and the outcomes of gas production profile tests.Additionally,significant correlations are observed between these parameters and cluster number,horizontal stress difference,and natural fracture density.This demonstrates the effectiveness of the proposed fracture parameter inversion method and the feasibility of field application.The findings of this study aim to provide solutions and references for the inversion of fracture parameters in shale gas wells.

Reliability Analysis of Repairable Systems Using Stochastic Point Processes

In order to analyze the failure data from repairable systems, the homogeneous Poisson process (HPP) is usually used. In general, HPP cannot be applied to analyze the entire life cycle of a complex, re-pairable system because the rate of occurrence of failures (ROCOF) of the system changes over time rather than remains stable. However, from a practical point of view, it is always preferred to apply the simplest method to address problems and to obtain useful practical results. Therefore, we attempted to use the HPP model to analyze the failure data from real repairable systems. A graphic method and the Laplace test were also used in the analysis. Results of numerical applications show that the HPP model may be a useful tool for the entire life cycle of repairable systems.

Meta-Test软件在诊断准确性试验Meta分析中运用

Meta-Test是一款专门用于诊断准确性试验(diagnostic test accuracy,DTA)Meta分析的常用软件。Meta-Test软件运行基于DOS系统,能以一种简单而直接地方式进行准确的数据处理和绘制精美而信息丰富的图形,并能进行亚组分析。其方便且有提示的操作、准确可靠数据处理及强大可用的绘图功能,使得其目前在DTA Meta分析中仍使用较为频繁,但其缺陷在于无法实现十字交叉图、散点图与边缘密度图的绘制。本文以一组DTA Meta分析的数据为例,系统展示本软件对数据的准备与分析、结果汇总及图形绘制等功能的相关操作过程。

Prototype Engineering Test Platform of ITER Magnet Gravity Support

ITER magnet gravity support （GS） has been redesigned as a structure of pre- assembled nmlti-flexible plates instead of the original welded structure. In the past several years, engineering tests of the new structure have been proposed. A prototype engineering test plat- form is being developed. In order to apply the loads/load combinations onto the test mock-up, seven hydraulic bolt tensioners in three directions have been applied to simulate various loads （forces and moments）, through which the deformation of bolts, flexible plates and clamp blocks, the stress distribution in the flexible plates, the friction between the contact surface, etc. can be monitored/tested. The measurement and control system includes seven sets of synchronization controller, a 16-channel strain gauge, 25 sets of displacement sensors, etc. Principles of EDC220 digital controller and development of multi-channel control software are also demonstrated.

DETERMINATION OF CREEP PROPERTIES OF THERMAL BARRIER COATING(TBC)SYSTEMS FROM THE INDENTATION CREEP TESTING WITH ROUND FLAT INDENTERS

Indentation creep behavior with cylindrical flat indenters on the thermal barrier coating (TBC) was studied by finite element method (FEM). On ike constant applied indentation creep stress, there is a steady creep rate for each case studied for different creep properties of the TBC system. The steady creep depth rate depends on the applied indentation creep stress and size of the indenters as well as the creep properties of the bond coat of the TBC and the substrate. The possibilities to determine the creep properties of a thermal barrier system from indention creep testing were discussed. As an example, with two different size indenters, the creep properties of bond coat of the TBC system can be derived by an inverse FEM method. This study not only provides a numerical method to obtain the creep properties of the TBC system, but also extends the application of indentation creep method with cylindrical flat indenters.

Mitigation of Low Frequency Oscillations by Optimal Allocation of Power System Stabilizers: Case Study on MEPE Test System

The increases in power network and weak tie-line have led power system oscillation problems. To improve the oscillatory stability, installing the power system stabilizer (PSS) with optimal allocation is considered due to excessive cost. This paper recommends the suitable PSS locations by using eigenvalue analysis and participation factor to enhance the system oscillation damping. The effects of installed PSSs in damping local and inter-area modes of oscillations are confirmed through time domain simulation results. The effectiveness of proposed approach is tested and validated on MEPE test system. Robustness of stabilizers against dynamic response of generator speed deviation, rotor angle deviation, and response of mechanical power are observed to access the performances of PSSs.

Predicting stability of integrated circuit test equipment using upper side boundary values of normal distribution

In response to the growing complexity and performance of integrated circuit(IC),there is an urgent need to enhance the testing and stability of IC test equipment.A method was proposed to predict equipment stability using the upper side boundary value of normal distribution.Initially,the K-means clustering algorithm classifies and analyzes sample data.The accuracy of this boundary value is compared under two common confidence levels to select the optimal threshold.A range is then defined to categorize unqualified test data.Through experimental verification,the method achieves the purpose of measuring the stability of qualitative IC equipment through a deterministic threshold value and judging the stability of the equipment by comparing the number of unqualified data with the threshold value,which realizes the goal of long-term operation monitoring and stability analysis of IC test equipment.

Analysis of State Homicide Rates Using Statistical Ranking and Selection Procedures

Nonparametric and parametric subset selection procedures are used in the analysis of state homicide rates (SHRs), for the year 2005 and years 2014-2020, to identify subsets of states that contain the “best” (lowest SHR) and “worst” (highest SHR) rates with a prescribed probability. A new Bayesian model is developed and applied to the SHR data and the results are contrasted with those obtained with the subset selection procedures. All analyses are applied within the context of a two-way block design.

中深层地埋管热泵供热系统运行特性实测研究

通过大量工程实测研究,总结了中深层地埋管热泵供热技术的运行特性。中深层地埋管具有出水温度高、取热功率大、长期运行稳定的特点,为热泵系统提供了高品位的低温热源,以提升其运行性能;同时中深层地埋管自身存在间歇蓄热特性,能很好地满足建筑供热需求变化与柔性用能;无级变频热泵机组更适合与中深层地埋管匹配运行,节能减排效果显著;热源侧水系统具有小流量、大扬程,且阻力随着流量变化而大幅度变化的特性。研究结果可为提升该技术的供热性能提供关键指导。

HFACS-MI改进模型在危险化学品仓储事故人因分析中的应用

为了研究危险化学品仓储事故的关键人因,通过人因分析与分类系统-煤矿(Human Factors Analysis and Classification System-Mine,HFACS-MI)改进模型从员工的不安全行为、影响不安全行为的前提条件、监督行为、组织影响和企业外部因素5个层次系统地分析65起危险化学品仓储事故,并运用卡方检验和让步比分析了产生不安全行为的原因和各层次间的内在关系。结果表明,外部管理、组织过程、监督不充分、个人因素、技能差错和违规是导致危险化学品仓储事故发生的重要因素。HFACS-MI改进模型上下层级的人为因素间存在显著的因果关系,且主要的危险化学品仓储事故致因路径共有5条,其中“外部管理因素—组织过程漏洞—监督不充分—个人因素—违规”是最关键的致因路径。改进的HFACS-MI模型可以有效分析危险化学品仓储事故人因因素。

非通航孔桥梁防船撞系统恒阻力装置研究

为给非通航孔桥梁防船撞系统拦截过程提供稳定持续的阻力,提出了一种利用耗能索持续协同大变形和连续破断输出稳定阻力的恒阻力装置。恒阻力装置由主绳、耗能索、破断环及其它连接件组成,与自适应浮筒、拦截网、系泊浮体等装置共同组成非通航孔桥梁自适应恒阻力船舶拦阻系统,有效拦截偏航船舶,保护非通航孔桥梁和来撞船舶的安全。通过理论分析研究该装置的阻力输出特性,建立该装置的阻力输出力学模型与计算方法,并通过拉伸破坏试验验证计算方法的准确性,进一步对影响装置阻力输出的耗能索的初始间距、长度及伸长率进行分析。结果表明:恒阻力装置能够有效地输出稳定且持续的阻力;耗能索初始间距越小,恒阻力装置阻力输出越大,阻力输出越稳定;耗能索长度或伸长率越大,恒阻力装置阻力输出越大,阻力输出越稳定。该装置已应用于力洋港大桥非通航孔区桥梁防撞中,有效地保护了大桥的安全。

基于FAST和Sobol指数法的雷达系统效能敏感性分析

为了以较小的代价快速提升对空探测雷达系统的综合效能,首先搭建了对空探测雷达系统综合效能的评估指标体系,在此基础上完成了综合效能评估模型的建立。选择两种基于方差原理的全局敏感性分析方法,即傅里叶幅度敏感性测试(Fourier amplitudes sensitivity test,FAST)和Sobol指数法,分别从频域和时域对建立的评估模型进行敏感性分析。在基于FAST进行敏感性分析时,提出了21维输入指标所对应的特征频率集的选取方法;在基于Sobol指数法进行敏感性分析时,考虑了二阶及高阶敏感性指数的影响。对比FAST和Sobol指数法的分析结果,两种方法获得的敏感性分析结果具有较好的一致性。其中,功率和频率为对空探测雷达系统的主要影响指标,为雷达系统的研发和升级提供了可靠性依据。

单点系泊液滑环驱动臂设计与验证

驱动臂是驱动液滑环与浮式生产储油轮(floating production storage and offloading,FPSO)之间发生相对转动的重要连接组件,避免连接传递偏心荷载引发密封失效是该装置的设计关键。依托南海奋进号FPSO液滑环的国产化项目,本文设计了一种多点铰接形式的柔性连接驱动臂,通过有限元分析校核了驱动臂设计结构的静态强度和疲劳强度。通过开展驱动臂的动态摇摆与旋转试验,验证了往复摆动工况下驱动臂的驱动功能与载荷传递性能,为FPSO单点系泊液滑环的国产化提供了重要参考。

高校分析测试中心实验室安全管理体系的构建

高校分析测试中心是实验教学、科研和社会服务的重要场所,是大型仪器共享平台的重要基地,因此,学校对分析测试中心实验室的安全管理提出了更高的要求。文章针对分析测试中心实验室的特点及安全管理现状进行分析,从管理制度的建立、安全教育培训的强化、定期监督巡查以及应急响应体系的建立等方面去探讨分析测试中心实验室安全管理体系的构建,并提出实验室安全管理持续改进的措施,为其他高校分析测试中心实验室安全管理提供参考。

激光选区熔化熔池监测系统设计与测试分析

熔池温度会影响制件的微观组织、残余应力,使之产生变形,而激光功率、扫描速度等工艺参数以及气流抖动、部件振动等不良因素会影响熔池形貌。对熔池温度和形貌进行监测与分析,对提升制件质量具有积极意义。结合热成像传感器设计了熔池温度监测系统,获取了熔池温度分布图像,建立了熔池温度场预测模型,并进行了不同激光功率作用下熔池温度测量实验。实验结果显示,理论熔池峰值温度与实际熔池峰值温度误差在-7%~-10%之间。结合高速工业相机设计了熔池形貌监测系统,获取了熔池形貌图像,通过图像滤波、图像分割、边缘检测、几何特征识别等处理,获得了熔池几何参数。该项目研究成果为激光选区熔化在线实时调节提供技术支撑。

基于符合性证据链的航电系统工程试验方法

为形成逻辑严密、可追溯的适航符合性验证资料,提出一种基于符合性证据链的航电系统工程试验方法,并对实现中的关键问题进行分析研究。以自动飞行控制系统的工程试验为例,设计与实现了基于自动飞行控制系统适航验证需求的验证平台。在验证方案设计中,针对复杂验证环境中部分参数不确定性描述问题,提出一种基于分类概率多场景分析的验证方案设计方法,基于适航验证需求,对飞行数据进行筛选,通过对筛选后的飞行数据进行统计特性分析、随机抽样与合并缩减,生成包含发生概率的确定性场景,描述验证环境中部分参数的不确定性。在验证数据分析中,针对多场景多参数条件下的适航符合性判断问题,提出基于加权Dempster-Shafer证据理论的适航符合性评估方法,以确定性场景发生概率为权重,进行证据融合,避免部分小概率场景对融合结果的干扰。基于实际飞行数据,自动飞行控制系统的自动飞行模式工程试验结果表明,所提方法有效可行。

组织视角下的核电厂班组决策失误致因分析

为了系统研究班组决策失误规律,识别核电厂班组决策失误的关键路径,从组织视角出发,结合核电厂所处环境与班组决策失误特征对人因分析与分类系统(Human Factor Analysis and Classification System,HFACS)模型进行改进,建立了核电厂班组决策失误致因模型。利用改进后的模型对137份核电厂事件报告进行统计分析,并运用卡方检验与让步比分析班组决策失误的原因及各层次之间的内在关系。结果表明,组织文化缺失、规程不明晰、知识与能力不足、制定备选方案失误是导致班组决策失误的重要因素。改进HFACS模型中上下层级的因素之间存在显著的因果关系,且容易引发班组决策失误的路径有32条,其中发生概率最大的路径为组织设计不当→任务不明晰→压力过大→确定目标失误。由此可见,核电事故的发生是各致因因素相互作用的结果,降低班组决策失误概率需要阻断关键致因路径,加强对关键因素的管控。

太阳能光热+市电耦合相变蓄能供暖系统测试分析

在环境污染和能源危机的双重背景下,太阳能是建筑供暖的首选能源。以太阳能光热+市电耦合相变蓄能(源侧及负荷侧)供暖系统为例,研究入口参数对相变蓄热装置蓄热过程的影响及有无相变蓄热地板对室温的影响。结果表明:提高入口温度和入口流量有利于缩短相变蓄热所需的时间;有相变蓄热地板的房间温度波动更平稳,舒适度更高。

高速铁路CTC系统试验方案探讨

CTC系统是高速铁路调度指挥的中枢,具有规模庞大及功能复杂等特点。因此,为其制定一套严谨且系统的开通试验方案至关重要。文章对比分析了CTC系统试验与微机联锁试验在步骤、内容、方法及原则上的差异,深入剖析了高速铁路CTC系统试验方案的6大要素。此外,文章结合具体案例进一步探讨了如何设计出更具实操性的试验表格,旨在为现场各级技术管理人员提供详尽、有益的参考。