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Improvement of sludge dewaterability with modified cinder via affecting EPS

Frontiers of Environmental Science & Engineering 2017年第6期11卷 179-192页

作者： Weichao Ma Lei Zhao Huiling Liu Qianliang Liu Jun Ma State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology Harbin 150090 China School of Architectural Engineering Heilongiiang University Harbin 150080 China Key Laboratory of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China Key Laboratory of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin 150090 China

The relationship between the improvement of sludge dewaterability and variation of organic matters has been studied in the process of sludge pre-conditioning with modified cinder, especially for extracellular polymeric substances （EPS） in the sludge. During the conditioning process, the decreases of total organic carbon （TOC） and soluble chemical oxygen demand （SCOD） were obviously in the supernatant especially for the acid modified cinder （ACMC）, which could be attributed to the processes of adsorption and sweeping. The reduction of polysaccharide and protein in supernatant indicated that ACMC might adsorb EPS so that the tightly bound EPS （TB-EPS） decreased in sludge. In the case of ACMC addition with 24 g·L^-1, SRF of the sludge decreased from 7.85 × 10^12 m·kg^-1 to 2.06× 10^12 m·kg^-1, and the filter cake moisture decreased from 85% to 60%. The reconstruction of ＂floc mass＂ was confirmed as the main sludge conditioning mechanism. ACMC promoted the dewatering performance through the charge neutralization and adsorption bridging with the negative EPS, and provided firm and dense structure for sludge floc as skeleton builder. The passages for water quick transmitting were built to avoid collapsing during the high-pressure process.

关键词： Sludge conditioning Acid or alkali modified cinder TB-EPS Floc mass Floc reconstruction

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Chemical composition of calcium-silicate-hydrate gels: Competition between kinetics and thermodynamics

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Physical Review Materials 2019年第6期3卷 065603-065603页

作者： Tao Du Hui Li Qi Zhou Zhe Wang Gaurav Sant Joseph V. Ryan Mathieu Bauchy Key Lab of Structures Dynamic Behavior and Control (Harbin Institute of Technology) Ministry of Education 150090 Harbin China School of Civil Engineering Harbin Institute of Technology 150090 Harbin China Physics of AmoRphous and Inorganic Solids Laboratory (PARISlab) Department of Civil and Environmental Engineering University of California Los Angeles California 90095 USA Laboratory for the Chemistry of Construction Materials (LC2) Department of Civil and Environmental Engineering University of California Los Angeles California 90095 USA California Nanosystems Institute (CNSI) University of California Los Angeles California 90095 USA Energy and Environment Directorate Pacific Northwest National Laboratory Richland Washington 99352 USA

Although concrete is the world's most widely used manufactured material, basic questions persist regarding the nature of its binding phase, namely, the calcium-silicate-hydrate (C-S-H) gel. Here, based on reactive molecular dynamics simulations, we address the following fundamental question: Is the chemical composition of C-S-H controlled by the kinetics or thermodynamics of its precipitation? As a major outcome of this study, we demonstrate that the average stoichiometry of the C-S-H gel forming upon the hydration of ordinary portland cement (i.e., Ca/Si = 1.75) is determined by the composition of the C-S-H phase presenting the fastest precipitation kinetics, rather than the highest thermodynamic stability.

关键词： Amorphous materials Gels Molecular dynamics

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Study on the performance of reinforced concrete blocks treated by styrene-acrylic emulsion

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Chemical Engineering Transactions 2018年 66卷 85-90页

作者： Zhu, Jing Zheng, Wenzhong Xie, Lili Wu, Yunqiang Zhang, Yongxin Fu, Junxiang Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration Harbin150080 China College of Civil Engineering and Architecture Harbin University of Science and Technology Harbin150080 China Key Lab of Structures Dynamic Behavior and Control of the Ministry Education Harbin Institute of Technology Harbin150090 China

This paper introduces a method of improving the performance of reinforced concrete blocks and reveals the reinforcing effect of fibers. It is pointed out that the plant fibers treated by styrene-acrylic emulsion can effectively improve the interfacial bonding conditions, for the modified straw fibers which were treated by alkali processing and acrylic coating, their performance has been significantly improved, which is conducive to absorbing energy and improving the strength of the material. This paper focuses on introducing three types of reinforced concrete blocks, it’s known that the bridging effect can effectively prevent the development of micro cracks. The occurrence of cracks increases the macroscopic tensile strain of the material and increases the ductility and toughness of the matrix. Studying plant fiber reinforced blocks will help promote the application of this new wall materials. Copyright © 2018, AIDIC Servizi S.r.l.

关键词： Tensile strain

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CCD deflection monitoring system for Songjiazhuang cloverleaf junction 24th

CCD deflection monitoring system for Songjiazhuang cloverlea...

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24th Australasian Conference on the Mechanics of structures and Materials, ACMSM 2016

作者： Shan, Baohua Wang, Lei Huo, Xiaoyang Yuan, Wenting Xue, Zhilin Ou, Jinping Key Laboratory of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin China School of Civil Engineering Harbin Institute of Technology Harbin China College of Civil Engineering and Architecture University of Jinan Jinan China

ISBN: (纸本)9781138029934

For long-term monitoring of the deflection of Songjiazhuang cloverleaf junction on 309 national roads in Zibo, this paper proposed a CCD-based bridge deflection monitoring method. Based on DIC principle, the bridge deflection is measured by tracking of targets’ position change in the FOV of CCD. The deflection monitoring software is compiled by MATLAB, and the deflection monitoring system for Songjiazhuang cloverleaf junction is integrated in this paper. This deflection monitoring system has functions such as 4-channel CCD cameras image preview, simultaneous acquisition, camera calibration, deflection display and data storage. Deflection curves obtained in the field show a consistent trend, this testifies that the proposed method is reliable and can meet the long-term monitoring requirements of bridge deflection. © 2017 Taylor & Francis Group, London.

关键词： CCD cameras

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LQD-RKHS-based distribution-to-distribution regression methodology for restoring the probability distributions of missing SHM data

arXiv

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arXiv 2018年

作者： Chen, Zhicheng Bao, Yuequan Li, Hui Spencer, Billie F. Key Lab of Intelligent Disaster Mitigation of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin China Key Lab of Structures Dynamic Behaviour and Control of the Ministry of Education Harbin Institute of Technology Harbin China School of Civil Engineering Harbin Institute of Technology Harbin China Department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign UrbanaIL United States Department of Civil and Environmental Engineering University of Illinois at Urbana - Champaign UrbanaIL United States

Data loss is a critical problem in structural health monitoring (SHM). Probability distributions play a highly important role in many applications. Improving the quality of distribution estimations made using incomplete samples is highly important. Missing samples can be compensated for by applying conventional missing data restoration methods;however, ensuring that restored samples roughly follow underlying distributions of true missing data remains a challenge. Another strategy involves directly restoring the probability density function (PDF) for a sensor when samples are missing by leveraging distribution information from another sensor with complete data using distribution regression techniques;existing methods include the conventional distribution-to-distribution regression (DDR) and distribution-to-warping function regression (DWR) methods. Due to constraints on PDFs and warping functions, the regression functions of both methods are estimated from the Nadaraya-Watson kernel estimator with relatively low degrees of precision. This article proposes a new indirect distribution-to-distribution regression method in the context of functional data analysis for restoring distributions of missing SHM data. PDFs are transformed to ordinary functions residing in a Hilbert space via the newly proposed log-quantile-density (LQD) transformation;the regression for distributions is realized in the transformed space via a functional regression model constructed based on the theory of Reproducing Kernel Hilbert Space (RKHS), corresponding result is subsequently mapped back to the density space through the inverse LQD transformation. Test results using field monitoring data indicate that the new method significantly outperforms conventional methods in general cases;however, in extrapolation cases, the new method is inferior to the distribution-to-warping function regression method. Copyright © 2018, The Authors. All rights reserved.

关键词： Probability distributions

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Review and analysis on spalling critical temperature of concrete and fibers dosage to prevent spalling at elevated temperatures

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Jianzhu Jiegou Xuebao/Journal of Building structures 2017年第1期38卷 161-170页

作者： Chen, Mingyang Hou, Xiaomeng Zheng, Wenzhong Wu, Bo Key Lab of Structures Dynamic Behavior and Control of China Ministry of Education Harbin Institute of Technology Harbin150090 China State Key Laboratory of Subtropical Building Science South China University of Technology Guangzhou510640 China

The principle of fire safety design is to ensure that concrete structures will not collapse or spall during fire and can be repaired after fire. There is important significance to research the spalling critical temperature of concrete without fibers or with lower fibers and rational fibers dosage to prevent spalling at elevated temperatures. The test results on fire-induced concrete spalling were analyzed. The relationship of spalling critical temperature and concrete cube compressive strength was obtained. Results show that the spalling critical temperature decreases with the increase of concrete compressive *** relationship of volume dosage of polypropylene (PP) fibers and steel fibers to prevent spalling and concrete compressive strength was obtained. The dosage of PP fibers increases linearly with the increase of concrete compressive strength, while the dosage of steel fibers increases with the increase of concrete compressive strength and the relationship can be expressed as an exponent *** is not safe to apply the recommendation in EN 1992-1-2: 2004 'Design of concrete structures: part 1-2: general rules: structural fire design' that the volume dosage 0.22% of PP fibers in concrete to prevent spalling. The proposed formula for fibers dosage will reduce the fire-induced spalling of concrete effectively. © 2017, Editorial Office of Journal of Building structures. All right reserved.

关键词： Steel fibers

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Study on the effect of ground motion direction on the response of engineering structure

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Earthquake Engineering and Engineering Vibration 2016年第4期15卷 649-656页

作者： Sun Menghan Fan Feng Sun Baitao Zhi Xudong Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology School of Civil Engineering Harbin Institute of Technology Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration

Due to the randomness of earthquake wave magnitude and direction, and the uncertain direction of strong axis and weak axis in the construction of engineering structures, the effect of the direction of ground motion on a structure are studied herein. Ground motion records usually contain three vertical ground motion data, which are obtained by sensors arranged in accordance with the EW （East -West） direction, NS （South- North） direction and perpendicular to the surface （z） direction, referring to the construction standard of seismic stations. The seismic records in the EW and NS directions are converted to Cartesian coordinates in accordance with the rotation of θ = 0°-180°, and consequently, a countless group of new ground motion time histories are obtained. Then, the characteristics of the ground motion time history and response spectrum of each group were studied, resulting in the following observations：（1） the peak and phase of ground motion are changed with the rotation of direction θ, so that the direction θ of the maximum peak ground motion can be determined; （2） response spectrum values of each group of ground motions change along with the direction θ, and their peak, predominant period and declining curve are also different as the changes occur; then, the angle θ in the direction of the maximum peak value or the widest predominant period can be determined; and （3） the seismic response of structures with different directions of ground motion inputs has been analyzed under the same earthquake record, and the results show the difference. For some ground motion records, such as the Taft seismic wave, these differences are significant. Next, the Lushan middle school gymnasium structure was analyzed and the calculation was checked using the proposed method, where the internal force of the upper space truss varied from 25% to 28%. The research results presented herein can be used for reference in choosing the ground motion when checking the actual damage to struct

关键词： direction of grotmd motion structure effect coordinate transformation response spectrum

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Damage Detection for SMC Benchmark Problem: A Subspace-Based Approach

Damage Detection for SMC Benchmark Problem: A Subspace-Based...

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作者： Zhou, Wensong Li, Shunlong Li, Hui Key Laboratory of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China School of Transportation Science and Engineering Harbin Institute of Technology Harbin150090 China Key Laboratory of Advanced Material and Intelligent Control Technology on Transportation Safety Harbin Institute of Technology Harbin150090 China

A full-scale bridge benchmark problem was issued by the Center of Structural Monitoring and control at the Harbin Institute of Technology. The data used in this problem were collected by an in situ structural health monitoring system implemented into a full-scale cable-stayed bridge before and after the bridge was damaged, which is very rare in structural health monitoring field. This benchmark problem will help to verify and/or make comparison of the condition assessment and the damage detection methods, which are usually validated by numerical simulation and/or laboratory testing of small-scale structures with assumed deterioration models and artificial damage. With respect to damage detection of girder, one of the benchmark problems, using the monitored and field testing acceleration data, this paper describes a damage detection method, based on a residual generated from a subspace-based covariance-driven identification method, to detect the damage, and give relative quantitative damage indexes. This method was applied on both two parts of the given benchmark problem, and then detailed discussions and results on this problem are reported in this paper. © 2016 World Scientific Publishing Company.

关键词： Damage detection

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Time-dependent reliability prediction analysis of bridge members considering dependence of failure modes and proof modes

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key Engineering Materials 2015年 648卷 25-34页

作者： Liu, Yuefei Lu, Dagang Key Laboratory of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin China School of Civil Engineering Harbin Institute of Technology Harbin China

Structural health monitoring systems used in bridges contain sensors providing a large amount of monitored data, such as stress, deflection and ***. In this paper, firstly, based on monitored everyday extreme stress data, time-variant proof load effects of structural members were defined, and based on the time-dependent proof load effects, the time-dependent performance functions of structural member's proof modes were built;and then based on the monitored data, the Bayesian dynamic models(BDMs) of extreme stresses were built, and based on the predicted extreme stress with BDMs, the time-variant performance functions of structural member's failure modes were given;and then based on the time-dependent performance functions of failure modes and proof modes and correlation coefficients between them, with the conditional probability method, the time-dependent reliability indices of structural members were updated and predicted;finally an actual engineering was provided to illustrate the application of the proposed models and methods. © 2015 Trans Tech Publications, Switzerland.

关键词： dynamic models

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封闭式鞍形张拉膜模型风致气弹响应研究（英文）

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2015年第8期16卷 656-668页

作者： Yue WU Zhao-qing CHEN Xiao-ying SUN Key Laboratory of Structures Dynamic Behavior and Control of Ministry of Education Harbin Institute of Technology Electric Power Research Institute Henan Electric Power Company

目的:明确张拉膜结构风致气弹响应特征及气弹失稳机理。,创新点:1.采用无接触测量技术设计鞍形张拉膜结构气弹模型风洞试验;2.研究鞍形张拉膜结构的气弹响应特征;3.给出鞍形张拉膜结构的失稳机理。方法:1.在风洞中测量两个形状相同但预... 详细信息

目的:明确张拉膜结构风致气弹响应特征及气弹失稳机理。,创新点:1.采用无接触测量技术设计鞍形张拉膜结构气弹模型风洞试验;2.研究鞍形张拉膜结构的气弹响应特征;3.给出鞍形张拉膜结构的失稳机理。方法:1.在风洞中测量两个形状相同但预张力不同的封闭式鞍形张拉膜结构气弹模型在不同风速下的均匀流中的位移响应及膜面上方不同高度的风速时程;2.通过对位移响应及风速时程进行,分析,明确结构的响应随风速变化特征及气弹失稳原因。.结论:1.膜结构在风荷载作用下变形到平衡位置,并.围绕该平衡位置以特定振幅进行振动;2.大部分风向角下,多个模态被激发,结构振幅及各阶模态阻尼比随风速增大而逐渐增大;3.特定风向角下,只有单阶模态被激发;低风速下,结构振幅和模态阻尼比随风速增大而缓慢增大;超过一定风速后,结构发生涡激共振引起的气弹失稳,振幅随风速增大开始迅速增大,达到不发生涡激共振时的2–4倍,结构阻尼比随风速增大发生迅速衰减;随着风速的继续增大,结构振动中可能出现其他模态的气弹失稳;4.结构前两阶模态的无量纲气弹失稳临界风速约为0.8–1.0。

关键词：膜结构风致响应气弹失稳气弹模型涡激共振

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