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Probabilistic description of extreme oscillations and reliability analysis in rolling motion under stochastic excitation

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Science China(Technological Sciences) 2023年第9期66卷 2586-2596页

作者： ZHAO Dan LI YongGe xu Yong LIU Qi KURTHS jürgen School of Mathematics and Statistics Northwestern Polytechnical UniversityXi’an 710072China MOE Key Laboratory for Complexity Science in Aerospace Northwestern Polytechnical UniversityXi’an 710072China Potsdam Institute for Climate Impact Research Potsdam 14412Germany Department of Physics Humboldt University BerlinBerlin 12489Germany

Large-amplitude rolling motions, also regarded as extreme oscillations, are a great threat to marine navigation, which may lead to capsizing in ship motion. Therefore, it is important to quantify extreme oscillations, assess reliability of ship systems, and establish a suitable indicator to characterize extreme oscillations in ship systems. In this work, extreme events are investigated in a ship model considering a complex ocean environment, described by a single-degree-of-freedom nonlinear system with stochastic harmonic excitation and colored Gaussian noise. The stationary probability density function(PDF) of the system is derived through a probabilistic decomposition-synthesis method. Based on this, we infer the classical damage rate of the system. Furthermore, a new indicator, independent of the PDF, is proposed to quantify the damage related only to the fourth-order moment of the system and the threshold for extreme events. It is more universal and easier to determine as compared with the classical damage rate. A large damping ratio, a large noise intensity, or a short correlation time can reduce the damage rate and the value of the *** findings provide new insights and theoretical guidance to avoid extreme oscillations and assess the reliability of practical ship movements.

关键词： rolling motion colored noise extreme oscillations reliability probabilistic decomposition-synthesis method

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植被混凝土不同磷石膏掺量对狗牙根根系特性及抗拔力学性能的影响

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三峡大学学报（自然科学版） 2025年第1期47卷 65-72页

作者：杨嘉槊吴彬康柔嘉许亚坤许文年三峡大学土木与建筑学院湖北宜昌443002 水泥基生态修复技术湖北省工程研究中心(三峡大学) 湖北宜昌443002 三峡大学水利与环境学院湖北宜昌443002 三峡大学生物与制药学院湖北宜昌443002

为研究植被混凝土磷石膏含量对基材理化性质、植物根系性征及整株抗拔力的影响,进行了不同磷石膏掺量(0%、3%、4.5%、6%、9%)以及不同生长期(90、120、150d)条件下,基材相关理化指标的测定、狗牙根根系监测和原位整株拉拔试验.结果表明... 详细信息

为研究植被混凝土磷石膏含量对基材理化性质、植物根系性征及整株抗拔力的影响,进行了不同磷石膏掺量(0%、3%、4.5%、6%、9%)以及不同生长期(90、120、150d)条件下,基材相关理化指标的测定、狗牙根根系监测和原位整株拉拔试验.结果表明:磷石膏对基材容重、pH值和土壤磷含量具有显著影响;狗牙根根系网状结构显著增强了抗拔力,整株抗拔力随根系性状的改善而增大,3%掺量下抗拔力120d时高出0%掺量30.25%;适量磷石膏掺入显著促进了根系生长,3%掺量下根系总根长、根体积和根系生物量增加显著,此种情况下狗牙根根系固土效果最好.

关键词：植被混凝土磷石膏根系形态抗拔力

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智能汽车横纵向控制研究综述

汽车文摘 2025年第1期 1-7页

作者：徐伟瑞重庆交通大学机电与车辆工程学院重庆400074

智能汽车作为汽车产业和全球智能化的关键一环,在整个智能化系统中扮演着至关重要的角色。为了探索智能汽车实现自动驾驶的关键技术,研究车辆的横向和纵向控制方法,利用车辆的运动学、动力学模型及轮胎模型,分析智能车辆的横向控制和纵... 详细信息

智能汽车作为汽车产业和全球智能化的关键一环,在整个智能化系统中扮演着至关重要的角色。为了探索智能汽车实现自动驾驶的关键技术,研究车辆的横向和纵向控制方法,利用车辆的运动学、动力学模型及轮胎模型,分析智能车辆的横向控制和纵向控制,采取解耦策略简化控制难度,确保车辆按照预定路径安全行驶。为确保车辆在运动时的稳定性,加强对车辆纵向控制的研究,以优化汽车速度管理。研究了车辆的耦合控制,以克服车辆耦合效应带来的问题,优化横向和纵向控制的精确度。总结了各种相关控制算法的优缺点,并提出了智能车辆横向和纵向控制的未来发展方向,包括:深化横向控制算法研究以提升安全性;优化纵向控制以确保运动稳定性;提升耦合控制精度以增强整体控制效果。

关键词：智能汽车车辆模型横纵向控制控制算法

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大跨度钢桁梁拱桥柔性拱整体提升施工关键技术

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国防交通工程与技术 2025年第1期23卷 86-91页

作者：许君辉渝万铁路有限责任公司重庆400037

清水坪乌江大桥主跨为240 m的下承式钢桁梁柔性拱桥,拱肋结构跨度大、自重大、施工复杂。主拱肋采用“两端原位拼装+中间段先卧拼后整体提升”的施工方案,整体提升过程中设置水平索以控制主拱肋受力和变形,根据施工阶段的实际受力需求... 详细信息

清水坪乌江大桥主跨为240 m的下承式钢桁梁柔性拱桥,拱肋结构跨度大、自重大、施工复杂。主拱肋采用“两端原位拼装+中间段先卧拼后整体提升”的施工方案,整体提升过程中设置水平索以控制主拱肋受力和变形,根据施工阶段的实际受力需求采取多工况提吊及水平张拉方法;具体介绍了拼装支架的布置和提升支架的结构。使用有限元分析软件进行模拟分析,保证了整体受力的安全性和抗风稳定性。施工中采用计算机控制液压同步提升技术,高效、经济、顺利的完成主拱肋架设工作。

关键词：钢桁梁-拱柔性拱主拱肋整体提升拼装支架有限元分析抗倾覆

“新工科”背景下重塑应用型高校实践教学体系的研究与探索

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科技风 2025年第1期 34-36页

作者：王旭戴佳洪许宜申苏州城市学院江苏苏州215000

“新工科”背景下,应用型高校人才培养目标是培养有坚定理想信念、扎实专业素养、广阔国际视野、远大志向的卓越工程人才。本研究针对目前应用型高校长期忽视实践教学环节和能力培养过程,且实践教学体系出现产教脱节,导致学生缺乏创造... 详细信息

“新工科”背景下,应用型高校人才培养目标是培养有坚定理想信念、扎实专业素养、广阔国际视野、远大志向的卓越工程人才。本研究针对目前应用型高校长期忽视实践教学环节和能力培养过程,且实践教学体系出现产教脱节,导致学生缺乏创造意识和创造能力,难以与社会产业转型升级需求相匹配等问题,探索重塑以实践课程为主体、科创项目和创新竞赛为两翼的“一体两翼”的立体式实践教学体系,并打造实践教学支撑平台,建设科教融合的大学生主题创新平台和产教融合协同育人平台,助力“新工科”人才培养,为加快培养适应社会和产业新需求的卓越工程科技人才做出贡献。

关键词：新工科实践教学科教产融合

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Ellipsometric Spectra and Optical Properties of Anisotropic SrBi2Ta2O9 Films

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Chinese Physics Letters 2004年第2期21卷 266-268页

作者：莫党刘毅 G.D.Hu j.B.xu StateKeyLaboratoryofOptoelectronicMaterialsandTechnologiesandDepartmentofPhysics ZhongshanUniversityGuangzhou510275 NormalCollege ShenzhenUniversityShenzhen518060 DepartmentofElectronicEngineeringandMaterialScienceandTechnologyResearchCenter TheChineseUniversityofHongKongHongKong

Ellipsometric spectra of the SrBi2Ta2O9 (SBT) films of (200) and (0010) predominant orientation are measured and analysed in the range of photon energy from 2 to 5 eV. The results show that the oriented SBT films appear to be strongly anisotropic. The ellipsometric spectra of the (200)-predominant SBT films are different from those of the (0010)-predominant films. We suggest an analysis model for these oriented films and perform the fitting of the anisotropic ellipsometric spectra. The refractive index and the extinction coefficient of the ordinary ray and the extraordinary ray for these oriented SBT films are obtained. The ordinary refractive index is larger than the extraordinary one.

关键词： Condensed matter: electrical magnetic and optical Surfaces interfaces and thin films

Microstructural Characterization of the Shear Bands in Fe-Cr-Ni Single Crystal by EBSD

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journal of Materials Science & Technology 2008年第6期24卷 819-828页

作者： Huajie YANG j.H.Zhang Yongbo xu Marc Andre＇ Meyers Shenyang National Laboratoryof Materials Sciences Institute of Metal Researchl Chinese Academy of Sciences Shenyang 110016 China University of California San Diego La Jolla CA92093-0411 USA

An investigation has been made into the microstructural characterization of the shear bands generated under high-strain rate （≈10^4 s^-1） deformation in Fe-15%Cr-15%Ni single crystal by EBSD-SEM （electron backscatter diffraction-scanning electron microscopy）, TEM （transmission electron in microscopy） and HREM （high- resolution electron microscopy）. The results reveal that the propagation of the shear band exhibits an asymmetrical behavior arising from inhomogenous distribution in plasticity in the bands because of different resistance to the collapse in different crystallographic directions; The γ-ε-α′phase transformations may take place inside and outside the bands, and these martensitic phases currently nucleate at intersections either between the twins and deformation bands or between the twins and ε-sheet. Investigation by EBSD shows that recrystallization can occur in the bands with a grain size of an average of 0.2μm in diameter. These nano-grains are proposed to attribute to the results of either dynamic or static recrystallization, which can be described by the rotational recrystallization mechanism. Calculation and analysis indicate that the strain rate inside the shear band can reach 2.50×10^6 s^-1, which is higher, by two or three orders of magnitude, than that exerted dynamically on the specimen tested.

关键词： High-strain rate deformation Adiabatic shear band Electron backscatter diffraction (EBSD) Recrystallization Fe-Cr-Ni single crystal

基于光谱技术的典型互花米草入侵湿地土壤属性预测研究

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光谱学与光谱分析 2025年第1期45卷 197-203页

作者：陈旭曹思珩杨仁敏陈秋宇李建国徐璐 4 江苏师范大学地理测绘与城乡规划学院地理信息科学系江苏徐州221116

为了高效监测互花米草入侵海岸带湿地生态系统的土壤属性变化,选取江苏省盐城湿地珍禽国家级自然保护区的一处典型互花米草入侵湿地作为研究区,利用随机分层采样方法选取15个样点,在3个深度(0~30、30~60、60~100 cm)共采集45个土壤样品... 详细信息

为了高效监测互花米草入侵海岸带湿地生态系统的土壤属性变化,选取江苏省盐城湿地珍禽国家级自然保护区的一处典型互花米草入侵湿地作为研究区,利用随机分层采样方法选取15个样点,在3个深度(0~30、30~60、60~100 cm)共采集45个土壤样品,测定了土壤可见光-近红外反射光谱和10种土壤理化属性,研究了偏最小二乘和随机森林两种方法的预测能力,分析了不同光谱变换形式对预测精度的影响,探讨了入侵年限和土壤深度作为辅助预测变量的潜力。结果表明:(1)可见光-近红外光谱技术可以较好地预测有机碳、无机碳、全氮、含水量、pH、容重、盐分和黏粒等属性;(2)偏最小二乘回归法比随机森林法更适合监测互花米草入侵湿地的关键土壤理化属性,利用偏最小二乘法对土壤属性建立的预测模型精度(R^(2))在0.341~0.979之间,随机森林方法对土壤属性建立的预测模型精度(R^(2))最高为0.722;(3)基于原始光谱可以获得土壤全氮的最优预测模型(R^(2)为0.769,RMSE为0.091 g·kg^(-1)),而其他土壤属性的最优模型多是基于微分变换或倒数变换建立的模型,微分变换和倒数变换可以有效地提高模型预测精度;(4)模型预测精度在加入入侵年限和土壤深度两个变量后总体上有所提高,其中有机碳、全氮、盐分、pH和容重等属性的预测精度对这两个变量更为敏感,土壤有机碳最优模型的精度(R^(2))从0.794提高到0.806,pH最优模型的精度(R^(2))从0.838提升至0.884,盐分最优模型的精度(R^(2))从0.978提升至0.997。综上所述,可见光-近红外光谱技术在互花米草入侵湿地关键土壤理化属性预测方面具有明显的优越性,通过适当的光谱变换、变量筛选、模型选择等方面可以实现互花米草入侵湿地土壤变化的快速监测。

关键词：互花米草入侵可见光-近红外光谱土壤监测偏最小二乘法随机森林光谱变换

[Solid-phase extraction coupled with high performance liquid chromatography-triple quadrupole mass spectrometry for simultaneous determination of seven coumarins in water samples from drinking water treatment plants]

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Se pu = Chinese journal of chromatography 2025年第1期43卷 78-86页

作者： Wen-Mei jiao jing-Ming Yang Ce xu Fu-Kang Gao Lu-Yao Shen Yu-Bo Yuan Zhi-Fen Guo Guang Huang School of Life Sciences and Chemical Engineering Jiangsu Second Normal University Nanjing 211200 China. School of Stomatology Nanjing Medical University Nanjing 210029 China. School of Public Health Nanjing Medical University Nanjing 211166 China. Key Laboratory of Modern Toxicology Ministry of Education School of Public Health Nanjing Medical University Nanjing 211166 China.

Chlorinated coumarins, which are as cytotoxic as highly toxic halobenzoquinones toward CHO-K1 cells, have recently been identified as disinfection byproducts in drinking water disinfection processes. Therefore, detecting coumarins in water samples collected at various stages from drinking water treatment plants helps assess the formation of chlorinated coumarins in drinking water. Hence, a simple, rapid, accurate, and sensitive method for quantifying coumarins in water samples is required. In this study, a method was developed based on solid-phase extraction coupled with high performance liquid chromatography-triple-quadrupole mass spectrometry for analyzing seven coumarins in water samples from drinking water treatment plants, including 6,7-dihydroxycoumarin, 7-hydroxycoumarin, 6-hydroxy-4-methylcoumarin, 8-chloro-7-hydroxycoumarin, coumarin, 7-chloro-6-hydroxy-4-methylcoumarin, and 3,8-dichloro-7-hydroxycoumarin. Sample pretreatment involved solid-phase extraction using HLB columns, followed by elution with water and methanol, each containing 0.25% formic acid. The extracted solution was separated via gradient elution using a Phenomenex Luna C18 column (100 mm×2.0 mm, 3 mm) with 0.1% formic acid aqueous solution and methanol as the mobile phases, with analytes detected by triple-quadrupole mass spectrometry equipped with electrospray ionization source in multiple reaction monitoring mode. The matrix effect, precision, and accuracy of the developed method were investigated using raw and treated water as matrices. Matrix effects of 0.84-1.12 were recorded for the detection of 6,7-dihydroxycoumarin, 7-hydroxycoumarin, 6-hydroxy-4-methylcoumarin, and coumarin in raw water, while values of 0.67-0.70 were recorded for 8-chloro-7-hydroxycoumarin, 7-chloro-6-hydroxy-4-methylcoumarin, and 3,8-dichloro-7-hydroxycoumarin in finished water. The three chlorinated coumarins exhibited matrix effects above 0.80 after the finished water matrix had been diluted four times. These re

关键词： coumarins disinfection byproducts drinking water high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) solid-phase extraction (SPE)