Repair and Strengthening Assessment of Existing Bridges Based on Time-Dependent Reliability Analysis

The strategy on repair and strengthening of existing bridges based on time-dependent reliability was analyzed with the maximum expected benefit as the objective function. A sample of risk-ranking decision was illustrated based on updated inspection information with 35 survival age. The effect of improvement of live loads and difference of repair methods on time-dependent reliability of existing bridges are considered. The results show that the decision method can be used in real project, with the cost of failure consequence and the risk of failure considered.

A reliable acoustic path:Physical properties and a source localization method

The physical properties of a reliable acoustic path （RAP） are analysed and subsequently a weighted-subspace~ fitting matched field （WSF-MF） method for passive localization is presented by exploiting the properties of the RAP environment. The RAP is an important acoustic duct in the deep ocean, which occurs when the receiver is placed near the bottom where the sound velocity exceeds the maximum sound velocity in the vicinity of the surface. It is found that in the RAP environment the transmission loss is rather low and no blind zone of surveillance exists in a medium range. The ray theory is used to explain these phenomena. Furthermore, the analysis of the arrival structures shows that the source localization method based on arrival angle is feasible in this environment. However, the conventional methods suffer from the complicated and inaccurate estimation of the arrival angle. In this paper, a straightforward WSF-MF method is derived to exploit the information about the arrival angles indirectly. The method is to minimize the distance between the signal subspace and the spanned space by the array manifold in a finite range-depth space rather than the arrival-angle space. Simulations are performed to demonstrate the features of the method, and the results are explained by the arrival structures in the RAP environment.

Time-Dependent Density-Functional Calculations for Optical Spectra of Na2 and Na4 Clusters

With the frame of the time-dependent local density approximation, an efficient description of the optical response of clusters has been used to study the photo-absorption cross section of Na2 and Na4 clusters. It is shown that our calculated results are in good agreement with the experiment. In addition, our calculated spectrum for the Na4 cluster is in better agreement with experiment than the GW absorption spectrum.

Structural Reliability Assessment by a Modified Spectral Stochastic Meshless Local Petrov-Galerkin Method

This study presents a new tool for solving stochastic boundary-value problems. This tool is created by modify the previous spectral stochastic meshless local Petrov-Galerkin method using the MLPG5 scheme. This modified spectral stochastic meshless local Petrov-Galerkin method is selectively applied to predict the structural failure probability with the uncertainty in the spatial variability of mechanical properties. Except for the MLPG5 scheme, deriving the proposed spectral stochastic meshless local Petrov-Galerkin formulation adopts generalized polynomial chaos expansions of random mechanical properties. Predicting the structural failure probability is based on the first-order reliability method. Further comparing the spectral stochastic finite element-based and meshless local Petrov-Galerkin-based predicted structural failure probabilities indicates that the proposed spectral stochastic meshless local Petrov-Galerkin method predicts the more accurate structural failure probability than the spectral stochastic finite element method does. In addition, generating spectral stochastic meshless local Petrov-Galerkin results are considerably time-saving than generating Monte-Carlo simulation results does. In conclusion, the spectral stochastic meshless local Petrov-Galerkin method serves as a time-saving tool for solving stochastic boundary-value problems sufficiently accurately.

Operation safety risk analysis method of hydropower project considering time-dependent effect

In order to consider the time-dependent characteristic of risk factors of hydropower project,the method of stochastic process simulating structure resistance and load effect is adopted.On the basis of analyzing the structure characteristics and mode of operation,the operation safety risk rate assessment model of hydropower project is established on the comprehensive application of the improved analytic hierarchy process,the time-dependent reliability theory and the risk rate threshold.A scheme to demonstrate the time-dependent risk rate assessment method for an example of the earth-rock dam is particularly implemented by the proposed approach.The example shows that operation safety risk rate is closely related to both the service period and design standard;considering the effect of time-dependent,the risk rate increases with time and the intersection of them reflects the technical service life of structures.It could provide scientific basis for the operation safety and risk decision of the hydropower project by predicting the trend of risk rate via this model.

Time-dependent reliability and resilience of aging structures exposed to multiple hazards in a changing environment

Engineering structures are often subjected to the influences of performance deterioration and multiple hazards during their service lives,and consequently may suffer from damage/failure as a result of external loads.Structural reliability and resilience assessment is a powerful tool for quantifying the structural ability to withstand these environmental or operational attacks.This paper proposes new formulas for structural time-dependent reliability and resilience analyses in the presence of multiple hazards,which are functions of the duration of the reference period of interest.The joint impacts of nonstationarities in multiple hazards due to a changing environment,as well as the deterioration of structural performance,are explicitly incorporated.The correlation between the structural resistances/capacities associated with different hazard types is modeled by employing a copula function.It is observed that,under the context of multiple hazards and aging effects,the time-dependent resilience takes a generalized form of time-dependent reliability.The proposed formulas can be used to guide the adaptive design of structures,where adaptive strategies are identified across a range of possible future service conditions.An example is presented to demonstrate the applicability of the proposed method for structural reliability and resilience analyses.

FNM method for estimating reliability of existing bridges

Combined with current specifications and stress characteristics of concrete filled steel tubular （CFST） arch bridges, the determination principle of safe-middle-failure threestage mode is given. Accordingly, damage probability and failure probability and the corresponding reliability indices are calculated; a direct relationship between reliability indices and three-stage working status is made. Based on the three-stage working mode, a combined FNM （finite element-neural network- Monte-Carlo simulation） method is put forward to estimate the reliability of existing bridges. According to time-dependent reliability theory, subsequent service time is divided into several stages; minimum samples required by the Monte-Carlo method are generated by random sampling; training samples are calculated by the finite element method, and the training samples are extended by the neural network; failure probability and damage probability are calculated by the Monte-Carlo method. Thus, time dependent reliability indices are obtained, and the working status is judged. A case study is investigated to estimate the reliability of an actual bridge by the FNM method. The bridge is a CFST arch bridge with an 83.6 m span and it has been in operation for 10 years. According to analysis results, in the tenth year, the example bridge is still in safe status. This conclusion is consistent with the facts, which proves the feasibility of the FNM method for estimating the reliability of existing bridges.

癌症患者家庭沟通量表的汉化及信效度检验

目的 汉化癌症患者家庭沟通量表(CCAT-PF),并检验其信效度。方法 采用Brislin模型将英文版CCAT-PF进行翻译、回译、文化调适与预测试;使用汉化后的CCAT-PF于2022年1-8月分别在391例癌症患者及391名家庭照顾者中进行调查,检验其信效度。结果 中文版CCAT-PF包括癌症患者(CCAT-P)及其家庭照顾者(CCAT-F)2个分量表,每个分量表各17个条目,各提取出4个公因子,CCAT-P和CCAT-F的Cronbach′s α系数分别为0.902、0.900,重测信度分别为0.956、0.927,累计方差贡献率分别为68.565%、67.750%,内容效度均为1。结论 中文版CCAT-PF信效度良好,可用于评估我国癌症患者及其家庭照顾者家庭沟通水平。

高海拔配电线路故障精准定位研究

为了维护高海拔地区输配电及用电工程线路的正常运行、提升供电的稳定性与质量,提出了高海拔配电线路故障精准定位方法。分析线路故障行波精准定位原理,实现故障点位的确认。通过计算故障电流波速和线路长度,实现行波双端定位。通过分析波速误差、线路长度误差和波头误差,提升高海拔输电线路行波定位精度。创新性地基于双端行波故障定位算法,以及小波变换、Hilbert-Huang变换方法,提出行波型故障预警与精准定位的优化措施。仿真模拟分析结果表明:所提方法能够迅速识别故障区间和故障准确位置,实现输配电线路故障的快速查找和故障点的精确定位。该方法的应用可以缩短电力线路运维人员的巡视时间、提升供电可靠性。

风电机组控制器国产化研制及应用

为摆脱技术壁垒,保障工业控制安全,实现信息安全的可控性,需对风电机组控制器进行国产化开发及替换应用。文章从实用性、完整性、实时性、可靠性、稳定性、安全性和先进性等方面考虑,采用国产龙芯2K1500芯片及国产嵌入式实时操作系统进行国产化控制器的设计开发,以达到安全可控、效能提高的目的;同时,基于所开发的国产化控制器,根据风电机组控制功能需求,完成风电机组控制系统的硬件组态和I/O点表配置,分析了控制器与接口设备的通信方式,并设计相应软件控制逻辑。现场应用结果显示,采用所设计控制器的风电机组成功投入运行后,完成了240 h试运行验收测试,验收测试阶段系统运行稳定可靠,各项性能指标满足相关标准规定,这证明了基于自主可控国产控制器的兆瓦级风电机组控制系统自主可控、安全可靠。

基于CANDU型核电站的高精度线性电源分析设计

40 V仪用直流电源国产化势在必行。在对电源应用场景和性能指标深入分析的基础上,设计出一款具有高可靠性、高性能、符合人机交互工学界面等特点的电源,第三方核级抗震试验、型式试验、老化试验、EMC试验结果表明该款40 V仪用直流电源的各项指标可完全比拟原用国外产品,并在电源安全防护和人机交互方面具有更好的性能。

医疗建筑手术室和ICU重点区域供配电设计探讨

结合参与设计的某三级甲等医院项目,总结医疗建筑中手术室和重症监护病房(ICU)供配电系统设计要点,包括UPS设置方案的选择、局部IT系统设计、手术室专用配电箱容量确定、手术部工艺设备的供配电、ICU床位设备带容量确定、净化空调供配电系统设计等。

Reliability and sensitivity of bogie frame of high-speed train with strength degradation

High-speed bogie frame is a key mechanical component in a train system. The reliability analysis of the bogie is necessary to the safety of high-speed train. Reliability analysis of a bogie frame was considered. The equivalent load method was employed to account for random repeated loads in structural reliability analysis. Degradation of material strength was regarded as a Gamma process. The probabilistic perturbation method was, then, employed for response moment computation. Example of a high-speed train bogie structure under time-variant load was employed for reliability and sensitivity analyses. Monte-Carlo simulation verifies the accuracy and efficiency of the proposed method in time-variant reliability analysis. The analysis results show that the reliability calculation considering the strength degradation and repeated load is closer to the practicality than the method of considering reliability calculation only. Its decreasing velocity is faster than the traditional reliability. The reliability sensitivity value changes over time. The analysis results provide a variation trend of reliability and sensitivity to design and usage of bogie frame.

Kriging-based reliability analysis of the long-term stability of a deep driftconstructed in the Callovo-Oxfordian claystone

Callovo-Oxfordian(COx)claystone has been considered as a potential host rock for geological radioactive waste disposal in France(Cigéo project).During the exploitation phase(100 years),the stability of drifts(e.g.galleries/alveoli)within the disposal is assured by the liner,which includes two layers:concrete arch segment and compressible material.The latter exhibits a significant deformation capacity(about 50%)under low stress(<3 MPa).Although the response of these underground structures can be governed by complex thermo-hydro-mechanical coupling,the creep behavior of COx claystone has been considered as the main factor controlling the increase of stress state in the concrete liner and hence the long-term stability of drifts.Therefore,by focusing only on the purely mechanical behavior,this study aims at investigating the uncertainty effect of the COx claystone time-dependent properties on the stability of an alveolus of Cigéo during the exploitation period.To describe the creep behavior of COx claystone,we use Lemaitre’s viscoplastic model with three parameters whose uncertainties are identified from laboratory creep tests.For the reliability analysis,an extension of a well-known Kriging metamodeling technique is proposed to assess the exceedance probability of acceptable stress in the concrete liner of the alveolus.The open-source code Code_Aster is chosen for the direct numerical evaluations of the performance function.The Kriging-based reliability analysis elucidates the effect of the uncertainty of COx claystone on the long-term stability of the concrete liner.Moreover,the role of the compressible material layer between the concrete liner and the host rock is also highlighted.

STRESS RELAXATION AND RELIABILITY EVALUATION OF SODA-LIME GLASS

Stress relaxation of glass is a dualism effect, it often lead to strength degradation in strengthened glass, but on the other hand, it improves the reliability and stress-uniformity of glasses. In this work, stress relaxation of soda-lime glass was investigated using three-point bending tests at 400-560℃ which is near the brittle to ductile transition temperature, for enhancing the safety of glass productions and exploring the most economic anneal process. The experimental results show that the speed of stress relaxation increases but the ultimate stress decreases with increasing temperature. The stress uniformity of the glass samples before and after anneal was examined using spherical indentation at arranged testing points. It indicates that the scatter of the local strength measured by the Hertzian indentation is smaller in the anneal glass than in initial specimen, so that the estimated Weibull modulus for the anneal specimen is higher. Furthermore, the strength evaluation by Hertzian indentation and statistical analysis was presented.

Electron localization of linear symmetric molecular ion H3-(2＋)

Electron localization in the dissociation of the symmetric linear molecular ion H3-（2＋） is investigated. The numerical simulation shows that the electron localization distribution is dependent on the central frequency and peak electric field amplitude of the external ultrashort ultraviolet laser pulse. When the electrons of the ground state are excited onto the 2pσ-2Σu-＋ by a one-photon process, most electrons of the dissociation states are localized at the protons on both sides symmetrically. Almost no electron is stabilized at the middle proton due to the odd symmetry of the wave function. With the increase of the frequency of the external ultraviolet laser pulse, the electron localization ratio of the middle proton increases, for more electrons of the ground state are excited onto the higher 3pσ-2Σu-＋ ustate. 50.9% electrons of all the dissociation events can be captured by the middle Coulomb potential well through optimizing the central frequency and peak electric field amplitude of the ultraviolet laser pulse. Besides, a direct current（DC） electric field can be utilized to control the electron motions of the dissociation states after the excitation of an ultraviolet laser pulse, and 68.8% electrons of the dissociation states can be controlled into the middle proton.

Charge Localization Induced by Reorientation of FA Cations Greatly Suppresses Nonradiative Electron-Hole Recombination in FAPbI3 Perovskites:a Time-Domain Ab Initio Study

Recent experiments report the rotation of FA(FA=HC[NH2]2+)cations significantly influence the excited-state lifetime of FAPbI3.However,the underlying mechanism remains unclear.Using ab initio nonadiabatic(NA)molecular dynamics combined with time-domain density functional simulations,we have demonstrated that reorientation of partial FA cations significantly inhibits nonradiative electron-hole recombination with respect to the pristine FAPbI3 due to the decreased NA coupling by localizing electron and hole in different positions and the suppressed atomic motions.Slow nuclear motions simultaneously increase the decoherence time,which is overcome by the reduced NA coupling,extending electron-hole recombination time scales to several nanoseconds and being about 3.9 times longer than that in pristine FAPbI3,which occurs within sub-nanosecond and agrees with experiment.Our study established the mechanism for the experimentally reported prolonged excited-state lifetime,providing a rational strategy for design of high performance of perovskite solar cells and optoelectronic devices.

System reliability evaluation of long railway subgrade slopes considering discrete instability

This paper develops a dual-indicator discrete method(DDM)for evaluating the system reliability performance of long soil subgrade slopes.First,they are segmented into many slope sections using the random finite element method,to ensure each section statistically contains one potential local instability.Then,the k-out-of-n system model is used to describe the relationship between the total number of sections n,the acceptable number of failure sections m,the reliability of sections R_(sec),and the system reliability R_(sys).Finally,m and R_(sys)are jointly used to assess the system reliability performance.For cases lacking spatial data of soil properties,a simplified DDM is provided in which long subgrade slopes are segmented by the empirical value of section length and R_(sec)is substituted by that of crosssections taken from them.The results show that(1)DDM can provide the probability that the actual number of local instabilities does not exceed a desired threshold.(2)R_(sys)decreases with increasing n or decreasing R_(sec);that is,it is likely to encounter more local instabilities for longer or weaker subgrade slopes.n is negatively related to the horizontal scale of fluctuation of soil properties and positively related to the total length of subgrade slopes L.(3)When L is sufficiently large,there is a considerable opportunity to meet local instabilities even if R_(sec)is large enough.

基于局部自适应代理模型的复合材料结构可靠性评估

为了评估复合材料复杂结构的可靠性,开展基于局部自适应代理模型的可靠性评估方法研究.针对复合材料翼盒结构,建立基于局部自适应算法的应力响应面代理模型和基于Weibull分布的强度分布模型,并基于蒙特卡洛法与Hashin准则计算翼盒结构的可靠性;同时开展复合材料翼盒结构的准静态拉伸试验,获得失效位置、失效形式及力-位移曲线,并以二项分布估计试验结果的置信度.结果表明:翼盒结构的失效位置位于上端拐角处,失效形式为基体剪切断裂与纤维拔出,材料参数中剪切模量对失效位置应力响应影响最大,结构需要优化设计减小拐角处剪切应力;基于局部自适应代理模型的可靠性评估数值分析结果与试验结果相对误差为5.295%,准确地评估了结构的可靠性.

国产化元器件替代可靠性评价与验证技术研究

国产化元器件在设计、工艺、原料等方面同进口元器件存在差异性,国产化元器件直接引入与应用会对终端产品可靠性产生影响,因此,需要制定相应评价与验证的质量保障体系,以确保终端应用产品的安全可靠。本文通过对国产化元器件选型标准与供应商管理,国内外元器件性能与结构比对分析,板级应用层面的可靠性验证与评价等相关技术内容的研究,构建了一套系统的国产化元器件替代可靠性评价与验证体系,为国产化元器件的导入与应用评价提供指导。