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A step forward towards a comprehensive framework for assessing liquefaction land damage vulnerability

Mahmood AHMAD, Xiao-Wei TANG, Jiang-Nan QIU, Feezan AHMAD, Wen-Jing GU

《结构与土木工程前沿（英文）》 2020年第14卷第6期页码 1476-1491 doi: 10.1007/s11709-020-0670-z

摘要： The unprecedented liquefaction-related land damage during earthquakes has highlighted the need to develop a model that better interprets the liquefaction land damage vulnerability (LLDV) when determining whether liquefaction is likely to cause damage at the ground’s surface. This paper presents the development of a novel comprehensive framework based on select case history records of cone penetration tests using a Bayesian belief network (BBN) methodology to assess seismic soil liquefaction and liquefaction land damage potentials in one model. The BBN-based LLDV model is developed by integrating multi-related factors of seismic soil liquefaction and its induced hazards using a machine learning (ML) algorithm-K2 and domain knowledge (DK) data fusion methodology. Compared with the C4.5 decision tree-J48 model, naive Bayesian (NB) classifier, and BBN-K2 ML prediction methods in terms of overall accuracy and the Cohen’s kappa coefficient, the proposed BBN K2 and DK model has a better performance and provides a substitutive novel LLDV framework for characterizing the vulnerability of land to liquefaction-induced damage. The proposed model not only predicts quantitatively the seismic soil liquefaction potential and its ground damage potential probability but can also identify the main reasons and fault-finding state combinations, and the results are likely to assist in decisions on seismic risk mitigation measures for sustainable development. The proposed model is simple to perform in practice and provides a step toward a more sophisticated liquefaction risk assessment modeling. This study also interprets the BBN model sensitivity analysis and most probable explanation of seismic soil liquefied sites based on an engineering point of view.

关键词： Bayesian belief network liquefaction-induced damage potential cone penetration test soil liquefaction structural learning and domain knowledge

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Detection of damage locations and damage steps in pile foundations using acoustic emissions with deep

Alipujiang JIERULA, Tae-Min OH, Shuhong WANG, Joon-Hyun LEE, Hyunwoo KIM, Jong-Won LEE

《结构与土木工程前沿（英文）》 2021年第15卷第2期页码 318-332 doi: 10.1007/s11709-021-0715-y

摘要： The aim of this study is to propose a new detection method for determining the damage locations in pile foundations based on deep learning using acoustic emission data. First, the damage location is simulated using a back propagation neural network deep learning model with an acoustic emission data set acquired from pile hit experiments. In particular, the damage location is identified using two parameters: the pile location ( ) and the distance from the pile cap ( ). This study investigates the influences of various acoustic emission parameters, numbers of sensors, sensor installation locations, and the time difference on the prediction accuracy of and . In addition, correlations between the damage location and acoustic emission parameters are investigated. Second, the damage step condition is determined using a classification model with an acoustic emission data set acquired from uniaxial compressive strength experiments. Finally, a new damage detection and evaluation method for pile foundations is proposed. This new method is capable of continuously detecting and evaluating the damage of pile foundations in service.

关键词： pile foundations damage location acoustic emission deep learning damage step

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Analysis of flow over backward facing step with transition

Dwarikanath RATHA,Arindam SARKAR

《结构与土木工程前沿（英文）》 2015年第9卷第1期页码 71-81 doi: 10.1007/s11709-014-0270-x

摘要： The present study deals with the study of the velocity distribution and the separation phenomenon of flow of air over a two dimensional backward facing step. The flow of air over a backward facing step has been investigated numerically using FLUENT. Flow simulation has been carried out in a backward facing step having an expansion ratio (ratio of the height before and after the step) of 1:1.94 and the results obtained are compared with the published experimental results. Comparison of flow characteristics between steps with three different transitions is made. The variation of reattachment length for all the three cases are analyzed for wide range of Reynolds number ranging from 100 to 7000 which covers the laminar, transition and turbulent flow of air. Simulation of the flow over steps with expansion ratios of 1:1.24, 1:1.38, 1:1.47, 1:1.53, 1:1.94, 1:2.20 are also carried out to examine the effect of different expansion ratios on the reattachment length. It is found that the primary reattachment length increases with increase in the expansion ratio. The primary reattachment length at the bottom wall downstream of the step is minimum for the step with round edged transition and maximum for the step with a vertical drop transition.

关键词： Reattachment length backward facing step transition flow separation k-? model

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One-step synthesis of recoverable CuCo

Tongzhou Lu, Yongzheng Zhang, Chun Cheng, Yanbin Wang, Yongming Zhu

《化学科学与工程前沿（英文）》 2020年第14卷第4期页码 595-604 doi: 10.1007/s11705-019-1818-z

摘要： A facile one-step hydrothermal method has been adopted to directly synthesize the CuCo S material on the surface of Ni foam. Due to the relatively large specific surface area and wide pore size distribution, the CuCo S material not only effectively increases the reactive area, but also accommodates more side reaction products to avoid the difficulty of mass transfer. When evaluated as anode for Li-ion batteries, the CuCo S material exhibits excellent electrochemical performance including high discharge capacity, outstanding cyclic stability and good rate performance. At the current density of 200 mA·g , the CuCo S material shows an extremely high initial discharge capacity of 2510 mAh·g , and the cycle numbers of the material even reach 83 times when the discharge capacity is reduced to 500 mAh·g . Furthermore, the discharge capacity can reach 269 mAh·g at a current of 2000 mA·g . More importantly, when the current density comes back to 200 mA·g , the discharge capacity could be recovered to 1436 mAh·g , suggesting an excellent capacity recovery characteristics.

关键词： copper cobalt sulfide recoverability one-step hydrothermal method anode material Li-ion battery

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论航空发动机发展的“渐改法”

温俊峰

《中国工程科学》 2000年第2卷第3期页码 23-26

摘要：

文章简要论述了航空发动机发展的两种途径及其特点，从国内外航空发动机改进发展广泛采用的作法和成功的经验事例，论证了“渐改”发展模式的规律性和重要性，提出了对发动机改进发展应加强组织领导和计划落实的建议。

关键词：航空发动机发动机发展途径渐改法

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一款基于改进的步进式译码算法实现的流水线架构RS码译码器 Article

Xing-ru PENG,Wei ZHANG,Yan-yan LIU

《信息与电子工程前沿（英文）》 2016年第17卷第9期页码 954-961 doi: 10.1631/FITEE.1500303

摘要：概要：基于改进的步进式译码算法，我们为超宽带系统设计了一款流水线架构的Reed-Solomon（RS）码译码器。为了减小复杂度，改进的步进式译码算法将传统步进式译码算法中冗余的两部分进行了结合。此外，采用流水线架构，使得所设计的译码器以最小时延获得最大吞吐率。因此，对于RS（23,17）码，我们所设计的译码器面积比ME（modified Euclidean）架构和pDCME（pipelined degree-computationless modified Euclidean）架构分别减少了42.5%和24.4%。此外，与传统步进式译码器相比，我们设计的译码器能减少11.3%的面积，且关键路径延迟更低。

关键词： Reed-Solomon码；步进式译码算法；超宽带；流水线架构

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Microplastics removal strategies: A step toward finding the solution

《环境科学与工程前沿（英文）》 2022年第16卷第1期页码 7-7 doi: 10.1007/s11783-021-1441-3

摘要：

Microplastics are an emerging threat and a big challenge for the environment. The presence of microplastics (MPs) in water is life-threatening to diverse organisms of aquatic ecosystems. Hence, the scientific community is exploring deeper to find treatment and removal options of MPs. Various physical, chemical and biological methods are researched for MPs removal, among which few have shown good efficiency in the laboratory. These methods also have a few limitations in environmental conditions. Other than finding a suitable method, the creation of legal restrictions at a governmental level by imposing policies against MPs is still a daunting task in many countries. This review is an effort to place all effectual MP removal methods in one document to compare the mechanisms, efficiency, advantages, and disadvantages and find the best solution.

关键词： Aquatic Coagulation Microplastics Plastic Water Treatment Plant Wastewater

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Practical consideration for design and optimization of the step feed process

Shijian GE, Yongzhen PENG, Congcong LU, Shuying WANG

《环境科学与工程前沿（英文）》 2013年第7卷第1期页码 135-142 doi: 10.1007/s11783-012-0454-3

摘要： Based on the anoxic/oxic (A/O) step feed process, a modified University of Cape Town (UCT) step feed process was developed by adding an anaerobic zone and adjusting sludge return pipeline. Performance evaluation of these two types of processes was investigated by optimizing operational parameters, such as the anaerobic/anoxic/oxic volumes, internal recycle ratios, and sludge retention times, for removal of chemical oxygen demanding (COD), nitrogen, and phosphorus. Results showed high removal efficiencies of COD of (85.0±1.7)%, ammonium of (99.7±0.2)%, total nitrogen (TN) of (85.5±1.7)%, phosphorus of (95.1±3.3)%, as well as excellent sludge settleability with average sludge volume index of (83.7±9.5) L·mg in the modified UCT process. Moreover, (61.5±6.0)% of influent COD was efficiently involved in denitrification or phosphorus release process. As much as 35.3% of TN was eliminated through simultaneous nitrification and denitrification process in aerobic zones. In addition, the presence of denitrifying phosphorus accumulating organisms (DNPAOs), accounting for approximately 39.2% of PAOs, was also greatly beneficial to the nitrogen and phosphorus removal. Consequently, the modified UCT step feed process was more attractive for the wastewater treatment plant, because it had extremely competitive advantages such as higher nutrient removal efficiencies, lower energy and dosages consumption, excellent settling sludge and operational assurance.

关键词： step feed anoxic/oxic (A/O) University of Cape Town (UCT) simultaneous nitrification and denitrification (SND) denitrifying phosphorus removal biological nutrient removal (BNR)

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One-step synthesis of

Kuiyi YOU, Fangfang ZHAO, Xueyan LONG, Pingle LIU, Qiuhong AI, Hean LUO

《化学科学与工程前沿（英文）》 2012年第6卷第4期页码 389-394 doi: 10.1007/s11705-012-1218-0

摘要： A simple and efficient approach for the synthesis of -caprolactam via the liquid phase nitrosation of cyclohexane and nitrosyl sulfuric acid in the presence of concentrated sulfuric acid has been developed. A series of novel AlVPO composites were prepared by an impregnation method and the composites were then employed to catalyze the nitrosation reaction of cyclohexane and nitrosyl sulfuric acid. Compared to the reaction using fuming sulfuric acid, the selectivity for the desired product was significantly improved using this one-step catalytic process. This method affords a shortcut to prepare -caprolactam and its analogs from cyclohexane.

关键词： cyclohexane ?-caprolactam AlVPO composite catalysts one-step synthesis concentrated sulfuric acid

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Windborne debris damage prediction analysis

Fangfang SONG, Jinping OU,

《结构与土木工程前沿（英文）》 2010年第4卷第3期页码 326-330 doi: 10.1007/s11709-010-0067-5

摘要： Windborne debris is one of the most important causes of the envelop destruction according to the post-damage investigations. The problem of windborne debris damage could be summarized as three parts, including windborne debris risk analysis, debris flying trajectories, and impact resistance of envelope analysis. The method of debris distribution is developed. The flying trajectories of compact and plate-like debris are solved by using a numerical method according to the different aerodynamic characteristics. The impact resistance of the envelopes is also analyzed. Besides, the process of windborne debris damage analysis is described in detail. An example of industrial building is given to demonstrate the whole method by using the observed data of typhoon Chanchu (2006). The method developed in this paper could be applied to risk assessment of windborne debris for structures in wind hazard.

关键词： typhoon windborne debris structural envelopes damage estimation

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Corrosion damage assessment and monitoring of large steel space structures

Bo CHEN, You-Lin XU, Weilian QU,

《结构与土木工程前沿（英文）》 2010年第4卷第3期页码 354-369 doi: 10.1007/s11709-010-0088-0

摘要： Large steel space structures, when exposed to a harsh corrosive environment, are inevitably subjected to atmospheric corrosion and stress corrosion cracking. This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion. The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced. The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking. Based on the results, the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.

关键词： large steel space structure atmospheric corrosion stress corrosion cracking corrosion damage damage assessment monitoring system

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Two-step hydrothermal conversion of biomass waste to humic acid using hydrochar as intermediate

《环境科学与工程前沿（英文）》 2023年第17卷第10期 doi: 10.1007/s11783-023-1719-8

摘要： Converting biomass materials to humic acid is a sustainable method for humic acid production and achieve biomass valorization. A two-step hydrothermal treatment method was adopted in this study to produce humic acid from corn stalks. In the first step of the process, hydrochar was prepared at different hydrothermal temperatures and pH values. Their chemical properties were then analyzed, and the hydrochar-derived humic acids were produced under alkaline hydrothermal conditions (denoted as HHA_alk). The hydrochar, prepared under high temperature (200 °C) and strong acidic (pH 0) conditions, achieved high HHA_alk yields (i.e., 67.9 wt% and 68.8 wt% calculated based on weight of hydrochar). The sources of HHA_alk formation were as follows: 1) production in the hydrochar preparation stage, and 2) increment under the alkaline hydrothermal treatment of hydrochar. The degree of hydrochar unsaturation was suggested as an indicator for evaluating the hydrochar humification potential under alkaline hydrothermal conditions. This study provides an important reference for the preparation of suitable hydrochar with high hydrothermal humification potential.

关键词： Biowaste Hydrochar Humic acid Hydrothermal parameter Unsaturation

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Creep life assessment of aero-engine recuperator based on continuum damage mechanics approach

《机械工程前沿（英文）》 2022年第17卷第4期 doi: 10.1007/s11465-022-0702-6

摘要： The creep life of an aeroengine recuperator is investigated in terms of continuum damage mechanics by using finite element simulations. The effects of the manifold wall thickness and creep properties of brazing filler metal on the operating life of the recuperator are analyzed. Results show that the crack initiates from the brazing filler metal located on the outer surface of the manifold with the wall thickness of 2 mm and propagates throughout the whole region of the brazing filler metal when the creep time reaches 34900 h. The creep life of the recuperator meets the requirement of 40000 h continuous operation when the wall thickness increases to 3.5 mm, but its total weight increases by 15%. Decreasing the minimum creep strain rate with the enhancement of the creep strength of the brazing filler metal presents an obvious effect on the creep life of the recuperator. At the same stress level, the creep rupture time of the recuperator is enhanced by 13 times if the mismatch between the minimum creep rate of the filler and base metal is reduced by 20%.

关键词： creep life assessment brazed joint continuum damage mechanics aeroengine recuperator

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Error measurement and assemble error correction of a 3D-step-gauge

MAO Xinyong, LI Bin, SHI Hanmin, LIU Hongqi, LI Xi, LI Peigen

《机械工程前沿（英文）》 2007年第2卷第4期页码 388-393 doi: 10.1007/s11465-007-0067-x

摘要： A new artifact called 3D-step-gauge consisting of a pyramid array and a compound, is proposed to calculate geometrical errors for machine tools. Only one point on each profile of the pyramid in the array is probed, and its center coordinate can be calculated. Then, the intervals of the pyramids can be transfered a length standard to measure errors. Considering the differences in the structural parameters and the location of the pyramids, a volumetric error measurement method of discrete points is presented. Furthermore, the location errors between the calibration state and the measurement state are studied and their influences on the accuracy of the position measurement are investigated on an actual machine tool. The 3D-step-gauge was tested on an actual machine tool and the measurement result shows quick assembly, convenient measurement, and high accuracy.

关键词： volumetric pyramid assembly accuracy calibration

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Bacterial inactivation, DNA damage, and faster ATP degradation induced by ultraviolet disinfection

Chao Yang, Wenjun Sun, Xiuwei Ao

《环境科学与工程前沿（英文）》 2020年第14卷第1期 doi: 10.1007/s11783-019-1192-6

摘要： • Long amplicon is more effective to test DNA damage induced by UV. • ATP in bacteria does not degrade instantly but does eventually after UV exposure. • After medium pressure UV exposure, ATP degraded faster. The efficacy of ultraviolet (UV) disinfection has been validated in numerous studies by using culture-based methods. However, the discovery of viable but non-culturable bacteria has necessitated the investigation of UV disinfection based on bacterial viability parameters. We used quantitative polymerase chain reaction (qPCR) to investigate DNA damage and evaluated adenosine triphosphate (ATP) to indicate bacterial viability. The results of qPCR effectively showed the DNA damage induced by UV when using longer gene amplicons, in that sufficiently long amplicons of both 16S and gadA indicated that the UV induced DNA damages. The copy concentrations of the long amplicons of 16S and gadA decreased by 2.38 log/mL and 1.88 log/mL, respectively, after exposure to 40 mJ/cm2 low-pressure UV. After UV exposure, the ATP level in the bacteria did not decrease instantly. Instead it decreased gradually at a rate that was positively related to the UV fluence. For low-pressure UV, this rate of decrease was slow, but for medium pressure UV, this rate of decrease was relatively high when the UV fluence reached 40 mJ/cm2. At the same UV fluence, the ATP level in the bacteria decreased at a faster rate after exposure to medium-pressure UV.

关键词： UV disinfection DNA damage qPCR ATP