Sensitivity analysis and probability modelling of the structural response of a single-layer reticulated dome subjected to an external blast loading

The structural response of a single-layer reticulated dome to external explosions is shaped by many variables,and the associated uncertainties imply non-deterministic results.Existing deterministic methods for predicting the consequences of specific explosions do not account for these uncertainties.Therefore,the impact of the uncertainties associated with these input variables on the structures’response needs to be studied and quantified.In this study,a parametric uncertainty analysis was conducted first.Then,local and global sensitivity analyses were carried out to identify the drivers of the structural dynamic response.A probabilistic structural response model was established based on sensitive variables and a reasonable sample size.Furthermore,some deterministic empirical methods for explosion-resistance design,including the plane blast load model of CONWEP,the curved blast load model under the 50%assurance level,and the 20%mass-increased method,were used for evaluating their reliability.The results of the analyses revealed that the structural response of a single-layer reticulated dome to an external blast loading is lognormally distributed.Evidently,the MB0.5 method based on the curved reflector load model yielded results with a relatively stable assurance rate and reliability,but CONWEP did not;thus,the 1.2MB0.5 method can be used for making high-confidence simple predictions.In addition,the results indicated that the structural response is very sensitive to the explosion parameters.Based on these results,it is suggested that for explosion proofing,setting up a defensive barrier is more effective than structural strengthening.

Finite Element Simulation Analysis of a Novel 3D-FRSPA for Crawling Locomotion

A novel three-dimensional-fiber reinforced soft pneumatic actuator(3D-FRSPA)inspired by crab claw and human hand structure that can bend and deform independently in each segment is proposed.It has an omni-directional bending configuration,and the fibers twined symmetrically on both sides to improve the bending performance of FRSPA.In this paper,the static and kinematic analysis of 3D-FRSPA are carried out in detail.The effects of fiber,pneumatic chamber and segment length,and circular air chamber radius of 3D-FRSPA on the mechanical performance of the actuator are discussed,respectively.The soft mobile robot composed of 3D-FRSPA has the ability to crawl.Finally,the crawling processes of the soft mobile robot on different road conditions are studied,respectively,and the motion mechanism of the mobile actuator is shown.The numerical results show that the soft mobile robots have a good comprehensive performance,which verifies the correctness of the proposedmodel.This work shows that the proposed structures have great potential in complex road conditions,unknown space detection and other operations.

Dynamic Interaction Analysis of Coupled Axial-Torsional-Lateral Mechanical Vibrations in Rotary Drilling Systems

Maintaining the integrity and longevity of structures is essential in many industries,such as aerospace,nuclear,and petroleum.To achieve the cost-effectiveness of large-scale systems in petroleum drilling,a strong emphasis on structural durability and monitoring is required.This study focuses on the mechanical vibrations that occur in rotary drilling systems,which have a substantial impact on the structural integrity of drilling equipment.The study specifically investigates axial,torsional,and lateral vibrations,which might lead to negative consequences such as bit-bounce,chaotic whirling,and high-frequency stick-slip.These events not only hinder the efficiency of drilling but also lead to exhaustion and harm to the system’s components since they are difficult to be detected and controlled in real time.The study investigates the dynamic interactions of these vibrations,specifically in their high-frequency modes,usingfield data obtained from measurement while drilling.Thefindings have demonstrated the effect of strong coupling between the high-frequency modes of these vibrations on drilling sys-tem performance.The obtained results highlight the importance of considering the interconnected impacts of these vibrations when designing and implementing robust control systems.Therefore,integrating these compo-nents can increase the durability of drill bits and drill strings,as well as improve the ability to monitor and detect damage.Moreover,by exploiting thesefindings,the assessment of structural resilience in rotary drilling systems can be enhanced.Furthermore,the study demonstrates the capacity of structural health monitoring to improve the quality,dependability,and efficiency of rotary drilling systems in the petroleum industry.

Finite Element Analysis for the Structure Optimization Design of the CPUE Load-Bearing Wheel of Tracked Vehicle

A new kind of material cast polyurethane elastomers (CPUE) is introduced to take the place of rubber on load bearing wheel for the first time. Based on load bearing wheel dimensions, material properties and operating conditions, the structure of wheel flange is optimized by zero order finite element method. A detailed three dimensional finite element model of flange of load bearing wheel is developed and utilized to optimize structure of wheel flange. Its service life, which is affected by flange structure parameter, is analyzed by comparing the optimization results with those of prototype of wheel. The results of optimization are presented and the stress field of load bearing wheel in optimal dimension obtained by using finite element analysis method is demonstrated. The finite element analysis and optimization results show that the CPUE load bearing wheel is feasible and suitable for the tracked vehicle and has a guiding value in practice of the weighting design of the whole tracked vehicle.

Sensitivity Study on Durability Variables of Marine Concrete Structures

In order to study the influence of parameters on durability of marine concrete structures, the parameter＇s sensitivity analysis was studied in this paper. With the Fick＇s 2nd law of diffusion and the deterministic sensitivity analysis method （DSA）, the sensitivity factors of apparent surface chloride content, apparent chloride diffusion coefficient and its time dependent attenuation factor were analyzed. The results of the analysis show that the impact of design variables on concrete durability was different. The values of sensitivity factor of chloride diffusion coefficient and its time dependent attenuation factor were higher than others. Relative less error in chloride diffusion coefficient and its time dependent attenuation coefficient induces a bigger error in concrete durability design and life prediction. According to probability sensitivity analysis （PSA）, the influence of mean value and variance of concrete durability design variables on the durability failure probability was studied. The results of the study provide quantitative measures of the importance of concrete durability design and life prediction variables. It was concluded that the chloride diffusion coefficient and its time dependent attenuation factor have more influence on the reliability of marine concrete structural durability. In durability design and life prediction of marine concrete structures, it was very important to reduce the measure and statistic error of durability design variables.

Reintervention with Transcatheter and Surgical Aortic Valves: A Systematic Review and Meta-Analysis

Background: Despite expanding indications, data regarding the long-term durability of transcatheter heart valves (THV) are limited. Methods: We performed a systematic review and meta-analysis of all published studies with ≥5years of follow-up reporting aortic valve reintervention rates of transcatheter (TAVR) and surgical aortic valve replacement (SAVR). Randomized controlled trials (n = 4) and propensity-matched observational studies (n = 1) involving all surgical risk categories were included. The primary endpoint was the composite of aortic valve reintervention and death. Results: The meta- analysis included 4145 patients: 2101 underwent TAVR (mean age 81.7 ± 6.7 years, 54% male) and 2044 SAVR (mean age 81.8 ± 6.6 years, 54% male). All TAVR procedures were performed with early generations of THV. At a median follow-up of 5 years (range 5 - 6 years), TAVR had higher reintervention rates (odds ratio (OR) 3.33;95% CI: [1.78, 6.24], p < 0.001, I2 = 0%), all-cause mortality (OR 1.45;95% CI: [1.22, 1.75], p < 0.001, I2 = 44%) and the composite of reintervention and death (OR 1.47;95% CI: [1.14, 1.91], p < 0.001, I2 = 64%). Rates of myocardial infarction, transient ischemic attack, stroke, endocarditis, and the composite of endocarditis and thrombosis were similar between the groups. Conclusion: Despite comparable short and medium-term results, TAVR with early-generation THV has higher rates of reintervention and the composite of reintervention and death. Further studies employing newer definitions of structural valve deterioration and bioprosthetic valve failure are needed to assess whether technological enhancements in THV technology will improve long-term outcomes.

“双减”政策何以有效落地?基于“任务-主体-结构”的政策文本分析和对S省的调查

聚焦“双减”政策何以有效落地问题进行了两个新尝试。一是在研究范式上,从应然逻辑、实然状态和必然进路三个层面回应。二是在分析框架上,融合政策执行过程相关研究和结构化理论构建了突出目标导向、强化结构分析的“任务-主体-结构”政策执行过程模型,更契合我国复杂的政策执行环境。基于对“双减”政策文本和S省的落地实践分析发现:第一阶段的落地过程呈现出“运动式”治理的特征,但实际执行结构、落地条件和落地成效在内涵上远未达到设定目标。建议着力推动向“动员式”转型,以高质量教育体系建设为总抓手,有效回应家长对政策的价值需求。

废玻璃粉对泡沫混凝土性能和微观孔结构的影响及其价值工程分析

玻璃研磨成粉后的主要成分与粉煤灰相似,具备潜在的火山灰活性。为提高我国对废弃玻璃的循环利用率,将泡沫混凝土与废玻璃粉结合用于改善泡沫混凝土性能,减少水泥消耗量,提高废玻璃的循环利用率。本文研究了以废玻璃粉作为胶凝材料替代部分水泥,并探究废玻璃粉对泡沫混凝土抗压强度、干密度、干缩率、软化系数等的影响。结果表明:在替代胶凝材料总质量的0%~30%(质量分数,下同)时,废玻璃粉会提高泡沫混凝土的抗压强度;且在废玻璃粉掺量为20%时,泡沫混凝土28、56 d抗压强度达到最大值;而在120 d时,废玻璃粉掺量为30%的泡沫混凝土抗压强度达到最大值。废玻璃粉会降低泡沫混凝土的干缩值,且掺量越大,干缩值的降低程度越大,这有助于解决泡沫混凝土易开裂的问题。废玻璃粉能够明显提高泡沫混凝土的软化系数,便于其在潮湿或水下环境应用。此外,从微观孔结构的角度对废玻璃粉引起的泡沫混凝土力学及耐久性能的变化规律做出解释,最后对废玻璃粉引入泡沫混凝土后的价值进行分析,定量证明了废玻璃粉的环保性和经济性。

在役边坡耐久性弱化及整体稳定性影响分析

针对在役边坡长期耐久性能弱化及对整体稳定性影响问题,首先依据混凝土结构耐久性原理,建立边坡支护结构耐久性弱化分析模型,结合室内耐久性加速试验进行验证分析,接着基于混合型非连续变形分析法(HDDA)扩展了锚杆单元连接不同位移模式块体的算法,利用该扩展型混合DDA法结合有限元法以分析耐久性弱化边坡稳定性问题,建立了总体计算基本框架。最后以浙江省某沿海公路边坡为案例进行分析,结果表明:在特定环境条件下边坡多型支护结构物在30~60 a内有锈胀开裂及断裂失效的可能性;假定锚杆不失效时边坡安全系数随年限增加存在一定降幅,而在考虑锚杆陆续失效时边坡安全系数降幅明显,需要提前采取加固措施。此外还表明混合型DDA法建模灵活、模拟结果合理,具有较好的应用价值。

施工周期和桥面铺装层对刚构桥挠度的影响分析

目前,刚构桥的下挠问题一直是影响其承载能力和耐久性的重要因素。论文主要分析了施工周期变化和桥面铺装层变化对刚构桥挠度的影响,并通过计算和建立有限元模型研究了施工周期和桥面铺装层对结构下挠的影响程度。

基于结构方程模型的心理问题预测算法设计

当前青年学生所面临的学习和生活压力越来越大,部分学生因无法有效排解压力而陷入心理危机,并由此造成了严重后果。针对缺少相对切实有效的心理问题预测算法的现状,提出了一种基于结构方程模型的相关预测算法。该算法从影响大学生心理问题的因素入手,筛选出其中主要的影响因素。并根据这些因素建立相应的心理危机指标体系及心理预警SEM模型,对模型进行分析以获得预测的结果。通过数值实验得到的结果,充分验证了所提心理问题预测算法的有效性与可行性。

山区大跨径桥梁细部结构设计及受力分析

文章围绕山区大跨径桥梁的细部结构设计及受力分析展开,为了解决复杂地形中桥梁建设技术问题,确保其安全性、可靠性与经济性,首先分析结构设计考虑因素、桥型的确定、主梁设计、支座与连接结构的设计,及桥面铺装与防水设计等关键技术细节,采用弹性力学、塑性力学等基本理论对桥梁的静态和动态响应进行计算分析,同时进行载荷分析及耐久性分析。研究结果表明:合理的材料选择和细部构造设计优化,能显著提升桥梁的耐久性,减少维护成本,本研究为山区大跨径桥梁设计和建设提供技术指导,对提升类似工程的设计质量和施工效率具有重要意义。

火灾后钢筋混凝土结构局部受损评价方法探讨

参照 T/CECS 252-2019《火灾后工程结构鉴定标准》对某工程进行火灾后检测鉴定工作。在进行钢筋混凝土结构构件检测鉴定过程中,以部分构件为例,进行火作用调查、初步鉴定评级和构件性能检测。在火作用调查中,根据现场残留物、构件外观、锤击声音、微观物相等,分析其内外曾达到最大温度;初步鉴定评级由油烟和烟灰、混凝土颜色、火灾裂缝、锤击反应、混凝土脱落、受力钢筋露筋、变形、柱倾斜等项目进行评定;在上述工作中,考虑构件现阶段实际状况,对检测人员和施工状况可能造成的影响进行比较分析,通过构件比对和回弹取芯,提出改善建议。

市政道路土岩组合边坡勘察要点解析及边坡稳定性分析

对市政道路土岩组合边坡勘察要点进行了深入细致的解析,对工程地质测绘和调查的方法及内容进行了分析,对土岩组合边坡勘探线、点进行了科学合理的布置,对主要岩土层及岩体结构面均提供了满足工程需要的边坡力学参数,对土岩组合边坡稳定性进行了全方位评价,对边坡可能存在的各种破坏模式进行了系统深入的计算分析,解决了工程实践中如何进行土岩组合边坡勘察及边坡稳定性分析的问题,其可为类似土岩组合边坡勘察及边坡稳定性分析提供借鉴和参考。

Primary Investigations on Yangtze River Bank Slope Stability in Wanzhou for the Three Gorges Reservoir Project

This paper investigates the main factors contributing to bank slope failures, such as the structure of rock and soil, water level change, bank slope gradient, vegetation, weathering and human activities. Based on these investigations, the bank slope failure models are analyzed. The stability of bank slopes in Wanzhou is investigated using geological surveying, 2D resistivity imaging surveying, excavated trenches and other methods. Finally, the disasters of bank slope failures in Wanzhou were investigated in detail. The results show that instability problems might occur in 60.38 km of bank slopes when the water level rises to 175 m. It is suggested that 37.8 km of unstable bank slopes should be stabilized, and 14.2 km of unstable banks should be moved or avoided after further geological surveying and reconnaissance. These results provide scientific basis and reliable data for the government to develop the third geodisaster prevention plan for the Three Gorges reservoir.

Analysis of Energy-saving Behavior among University Students in Vietnam

Currently, in the course of serious environmental problems where the cause is anthropogenic, such as global wanning, not only the technology and policies but also the promotions of pro-environmental behavior are required. However, previous studies reported a gap between high environmental awareness and behavior. So to promote this practice, it is necessary to clarify the determinants that lead to practice. Because of the rapid economic growth in developing countries, including Vietnam, pollution problems and energy consumption are of major importance. This study aims to propose methods to promote pro-environmental practices based on a questionnaire and statistical analysis that investigated university students in Vietnam＇s Ho Chi Minh city. From the factor analysis, in actions to do with the power-saving behavior of standby power and home electronics, and the use of air conditioning, four evaluation criteria including effectiveness, cost feasibility, convenience, and social norms are extracted. The covariance structure analysis showed that the evaluation of convenience represented the strongest causal relation to a given power-saving action, and the action, in turn, can lead to improvements in most practical activities so as to enhance their convenience. Finally, several methods to save energy are proposed based on the results of the questionnaire.

铁磷摩尔比对含锆铁磷酸盐玻璃陶瓷结构和化学稳定性的影响

以P_(2)O_(5)-Fe_(2)O_(3)-Al_(2)O_(3)-Na_(2)O四元玻璃作为基础,掺入x=6%(摩尔分数)的ZrO_(2),改变基质玻璃的Fe/P摩尔比(r(Fe/P)),采用熔淬法制备一系列玻璃陶瓷样品,研究含ZrO_(2)的玻璃陶瓷结构和化学稳定性随Fe/P摩尔比的变化。X射线衍射用于物相分析,拉曼光谱、X射线光电子能谱和穆斯堡尔谱用于结构分析。Fe/P摩尔比小于0.18时,样品中Fe^(3+)的相对含量(n(Fe^(3+))/(n(Fe^(2+))+n(Fe^(3+)))摩尔比)随着r(Fe/P)增加而增多;r(Fe/P)介于0.18~0.32时,n(Fe^(3+))/(n(Fe^(2+))+n(Fe^(3+)))在60%左右波动。r(Fe/P)介于0.2~0.3时,样品的化学稳定性最好。

多海域混凝土结构的耐久性监测及其数据分析

介绍了国内多个海域海工结构的混凝土结构耐久性监测技术的应用状况,对监测传感器长期持续采集的耐久性监测数据进行分析,并结合现场氯离子渗透试验结果综合评估结构耐久性健康状况。最后,针对混凝土结构耐久性监测中存在的问题,提出建设性意见。

初级汉语学习者习得“上+O”结构的情况考察与分析

本文考察了初级汉语学习者习得“上+O”结构的总体情况,并对习得中出现的偏误现象进行了分析。研究表明,因学习内容、学习态度、语言使用环境、母语干扰等因素影响,初级汉语学习者在习得“上+O”结构时容易出现多余、误用、遗漏、错序和杂糅等偏误现象,由此可为国际中文教学者和学习者提供参考。

水下采油树S密封结构优化与试验研究

S密封作为水下采油树的非金属密封圈,是水下安全生产的关键部件之一。以S密封为研究对象,进行了结构和密封机理的研究并对其结构参数进行优化。通过建立有限元仿真模型,研究了密封圈截面长度、截面宽度、弹簧直径及圆弧半径等参数对密封圈性能的影响规律,并根据影响显著性采用响应面法对密封圈的关键结构参数进行优化分析,以最小等效应力与最大接触应力为目标,对密封圈结构参数进行优化。将优化后的S密封与优化前进行对比,结果得出在安全性能和密封性能上S密封均有显著的提升;最后通过静压试验对S密封进行了密封性能测试,试验结果表明S密封满足密封性能要求。研究方法和结果可为S密封以及其他类似结构密封圈的结构优化提供理论依据及数据参考。