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Damage identification of a large-span concrete cable-stayed bridge based on genetic algorithm

ZHU Jinsong, XIAO Rucheng

《结构与土木工程前沿（英文）》 2007年第1卷第2期页码 170-175 doi: 10.1007/s11709-007-0018-y

摘要： The global stability of a structure, the stiffness of its main girder and concrete tower, and the variation of the forces of its stay cables are key issues to the safety assessment of an in-service cable-stayed bridge. The efficiency and rationality of local elaborate non-damage-identification could be enhanced by the primary damage identification of cable-stayed bridges on the basis of periodic detection of the cable force and strain monitor in key sections of the main girder. The genetic algorithms of damage identification for cable-stayed bridges were investigated in this paper on the basis of the monitor data of the cable force and strain in a key section of the main girder. A damage detection program for complex civil structure was generated to implement the identification of damage location and extent. The deterioration of the structure was calculated according to the variation of monitor data. It is demonstrated that the results of damage identification from the parametric finite element method are accurate. The method had been verified using a long-span concrete cable-stayed bridge in Ningbo, which has been in use for the past four years.

关键词： accurate primary global stability complex identification

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Solvates and polymorphs of clindamycin phosphate: Structural, thermal stability and moisture stability

Junbo Gong, Dejiang Zhang, Yuanyuan Ran, Keke Zhang, Shichao Du

《化学科学与工程前沿（英文）》 2017年第11卷第2期页码 220-230 doi: 10.1007/s11705-017-1624-4

摘要： Clindamycin phosphate (CP), an antibacterial agent, has been reported to form several solid-state forms. The crystal structures of two CP solvates, a dimethyl sulfoxide (DMSO) solvate and a methanol/water solvate (solvate V), have been determined by single crystal X-ray diffraction. The properties and transformations of these forms were characterized by powder X-ray diffraction, Single-crystal X-ray diffraction, differential scanning calorimetry, thermo gravimetric analysis, hot-stage microscopy, and dynamic vapor sorption. Very different hydrogen bonding networks exist among the host-host and host-solvent molecules in the two crystal structures, resulting in different moisture stabilities. The thermal stabilities of the two solvates upon heating and desolvation were also studied. When the temperature was above the boiling point of methanol, solvate V converted to a polymorphic phase after a one step desolvation process, whereas the desolvation temperature of the DMSO solvate was below the boiling point of DMSO. At the relative humidity above 43%, the DMSO solvate transformed to a hydrate at 25 °C. In contrast, solvate V did not transform at any of the humidities studied.

关键词： clindamycin phosphate solvate crystal structure thermal stability moisture stability

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一类Lipschitz非线性系统的事件触发动态输出反馈控制 Research Article

刘智倩,楼旭阳,贾佳佳

《信息与电子工程前沿（英文）》 2022年第23卷第11期页码 1684-1699 doi: 10.1631/FITEE.2100552

摘要：

本文研究一类Lipschitz非线性系统的动态输出反馈控制问题。首先，针对该系统设计了一个连续时间控制器，并且给出了系统稳定的充分条件。其次，针对该Lipschitz非线性系统提出一种新的事件触发机制，在该触发机制中引入了新的事件触发条件，并构建了事件触发控制下的闭环混杂系统。在混杂系统框架下建立了闭环系统稳定的充分条件。此外，给出了最小事件间隔的上界，以避免Zeno现象。最后，通过在神经网络系统和基因调控网络系统中的数值仿真验证了理论结果及所提方法的优越性。

关键词： Lipschitz非线性系统；动态输出反馈控制；事件触发控制；全局渐近稳定

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脉冲型惯性双向联想记忆神经网络新解 Research Articles

Chaouki AOUITI, Mahjouba Ben REZEG, Yang CAO

《信息与电子工程前沿（英文）》 2020年第21卷第2期页码 324-339 doi: 10.1631/FITEE.1900181

摘要：探究了具有混合时滞和脉冲效应的惯性双向联想记忆神经网络。该研究为类似系统的反周期解的存在性、唯一性和全局指数稳定性提供了新的实用条件。使用微分不等式技术证明我们的主要结果，并给出一个仿真算例证明新结果的有效性。

关键词：惯性神经网络；反周期解；全局指数稳定；脉冲；时变延迟；双向联想记忆

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Evaluation and prediction of slope stability using machine learning approaches

《结构与土木工程前沿（英文）》 2021年第15卷第4期页码 821-833 doi: 10.1007/s11709-021-0742-8

摘要： In this paper, the machine learning (ML) model is built for slope stability evaluation and meets the high precision and rapidity requirements in slope engineering. Different ML methods for the factor of safety (FOS) prediction are studied and compared hoping to make the best use of the large variety of existing statistical and ML regression methods collected. The data set of this study includes six characteristics, namely unit weight, cohesion, internal friction angle, slope angle, slope height, and pore water pressure ratio. The whole ML model is primarily divided into data preprocessing, outlier processing, and model evaluation. In the data preprocessing, the duplicated data are first removed, then the outliers are filtered by the LocalOutlierFactor method and finally, the data are standardized. 11 ML methods are evaluated for their ability to learn the FOS based on different input parameter combinations. By analyzing the evaluation indicators R ², MAE, and MSE of these methods, SVM, GBR, and Bagging are considered to be the best regression methods. The performance and reliability of the nonlinear regression method are slightly better than that of the linear regression method. Also, the SVM-poly method is used to analyze the susceptibility of slope parameters.

关键词： slope stability factor of safety regression machine learning repeated cross-validation

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SUSTAINABLE NITROGEN MANAGEMENT INDEX: DEFINITION, GLOBAL ASSESSMENT AND POTENTIAL IMPROVEMENTS

《农业科学与工程前沿（英文）》 2022年第9卷第3期页码 356-365 doi: 10.15302/J-FASE-2022458

摘要：

● A composite N management index is proposed to measure agriculture sustainability.

关键词： global assessment indicator nitrogen management sustainable agriculture sustainable development goals

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Modified Bishop method for stability analysis of weakly sloped subgrade under centrifuge model test

《结构与土木工程前沿（英文）》 2021年第15卷第3期页码 727-741 doi: 10.1007/s11709-021-0730-z

摘要： The sliding forms of weak sloped and horizontal subgrades during the sliding process differ. In addition, the sliding form of weakly sloped subgrades exhibits considerable slippage and asymmetry. The accuracy of traditional slice methods for computing the stability safety factor of weakly sloped subgrades is insufficient for a subgrade design. In this study, a novel modified Bishop method was developed to improve the accuracy of the stability safety factor for different inclination angles. The instability mechanism of the weakly sloped subgrade was considered in the proposed method using the “influential force” and “additional force” concepts. The “additional force” reflected the weight effect of the embankment fill, whereas the “influential force” reflected the effect of the potential energy difference. Numerical simulations and experimental tests were conducted to evaluate the advantages of the proposed modified Bishop method. Compared with the traditional slice method, the error between the proposed method and the exact value is less than 32.3% in calculating the safety factor.

关键词： weakly sloped subgrade stability analysis additional force influential force modified Bishop method

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Engineering management: Global engineering research frontiers

Botao ZHONG, Luting QIU

《工程管理前沿（英文）》 2020年第7卷第1期页码 159-162 doi: 10.1007/s42524-020-0094-4

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Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

《结构与土木工程前沿（英文）》 2023年第17卷第4期页码 522-532 doi: 10.1007/s11709-023-0930-9

摘要： Owing to long-distance advancement or obstacles, shield tunneling machines are typically shut down for maintenance. Engineering safety during maintenance outages is determined by the stability of the tunnel face. Pressure maintenance openings are typically used under complicated hydrogeological conditions. The tunnel face is supported by a medium at the bottom of the excavation chamber and compressed air at the top. Owing to the high risk of face failure, the necessity of support pressure when cutterhead support is implemented and a method for determining the value of compressed air pressure using different support ratios must to be determined. In this study, a non-fully chamber supported rotational failure model considering cutterhead support is developed based on the upper-bound theorem of limit analysis. Numerical simulation is conducted to verify the accuracy of the proposed model. The results indicate that appropriately increasing the specific gravity of the supporting medium can reduce the risk of collapse. The required compressed air pressure increases significantly as the support ratio decreases. Disregarding the supporting effect of the cutterhead will result in a tunnel face with underestimated stability. To satisfy the requirement of chamber openings at atmospheric pressure, the stratum reinforcement strength and range at the shield end are provided based on different cutterhead aperture ratios.

关键词： tunnel face stability cutterhead configuration aperture ratio pressure gradient support ratio

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MANURE AND METROPOLES---A GLOBAL FRAMEWORK FOR NUTRIENT CYCLING IN FOOD SYSTEMS

《农业科学与工程前沿（英文）》 2021年第8卷第1期

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Soil security and global food security

《农业科学与工程前沿（英文）》 doi: 10.15302/J-FASE-2023530

摘要：

● Much of the world’s agricultural land has been degraded through soil loss and degradation of soil organic matter.

关键词： Agriculture soil security food security regenerative

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Effect of undercut on the lower bound stability of vertical rock escarpment using finite element and

Shuvankar DAS; Debarghya CHAKRABORTY

《结构与土木工程前沿（英文）》 2022年第16卷第8期页码 1040-1055 doi: 10.1007/s11709-022-0841-1

摘要： In the present study, the stability of a vertical rock escarpment is determined by considering the influence of undercut. Lower bound finite element limit analysis in association with Power Cone Programming (PCP) is applied to incorporate the failure of rock mass with the help of the Generalized Hoek-Brown yield criterion. The change in stability due to the presence of undercut is expressed in terms of a non-dimensional stability number (σ_ci/γH). The variations of the magnitude of σ_ci/γH are presented as design charts by considering the different magnitudes of undercut offset (H/v_u and w_u/v_u) from the vertical edge and different magnitudes of Hoek-Brown rock mass strength parameters (Geological Strength Index (GSI), rock parameter (m_i,), Disturbance factor (D)). The obtained results indicate that undercut can cause a severe stability problem in rock mass having poor strength. With the help of regression analysis of the computed results, a simplified design equation is proposed for obtaining σ_ci/γH. By performing sensitivity analysis for an undisturbed vertical rock escarpment, we have found that the undercut height ratio (H/v_u) is the most sensitive parameter followed by GSI, undercut shape ratio (w_u/v_u), and m_i. The developed design equation as well as design charts can be useful for practicing engineers to determine the stability of the vertical rock escarpment in the presence of undercut. Failure patterns are also presented to understand type of failure and extent of plastic state during collapse.

关键词： undercut vertical escarpment stability Hoek-Brown yield criterion PCP

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Correction to: Effect of undercut on the lower bound stability of vertical rock escarpment using finite

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0035-5

摘要： Correction to: Effect of undercut on the lower bound stability of vertical rock escarpment using finite element and power cone programming

关键词： finite element power stability rock escarpment

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Influence of boundary conditions and turntable speeds on the stability of hydrostatic oil cavity

Zhaomiao LIU, Chengyin ZHANG, Feng SHEN

《机械工程前沿（英文）》 2011年第6卷第3期页码 359-368 doi: 10.1007/s11465-011-0222-2

摘要：

The flow, bearing, and carrying capacity of the cycloidal hydrostatic oil cavity in hydrostatic turntable systems are numerically simulated, considering the rotation speeds of a turntable from 0 to 5 m/s and different boundary conditions. The vortex effect is weakened, and the stability of the oil cavity is enhanced with the increase in lubricant viscosity. However, the increase in inlet speed, depth, and inlet radius of the oil cavity causes the vortex effect to increase and the stability of oil cavity to reduce. With the increase in the oil film thickness, the carrying capacity of the oil cavity diminishes. The oil cavity pressure increases along the direction of the motion of the turntable; it is distributed unevenly because of the rotation of the turntable. With the increase in turntable speed, the location and size of the vortex scope in the oil cavity flow field and the strength of the vortex near the entrance gradually weaken and move away from the entry. The distribution of pressure is determined by the locations of the vortex. When the vortex is close to the wall, the wall pressure increases at its location. Otherwise, the wall pressure decreases first and then increases after the center of the vortex.

关键词： hydrostatic oil cavity flow state oil cavity pressure stability vortex