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Centrifuge experiments for shallow tunnels at active reverse fault intersection

Mehdi SABAGH, Abbas GHALANDARZADEH

《结构与土木工程前沿(英文)》 2020年 第14卷 第3期   页码 731-745 doi: 10.1007/s11709-020-0614-7

摘要: Tunnels extend in large stretches with continuous lengths of up to hundreds of kilometers which are vulnerable to faulting in earthquake-prone areas. Assessing the interaction of soil and tunnel at an intersection with an active fault during an earthquake can be a beneficial guideline for tunnel design engineers. Here, a series of 4 centrifuge tests are planned and tested on continuous tunnels. Dip-slip surface faulting in reverse mechanism of 60-degree is modeled by a fault simulator box in a quasi-static manner. Failure mechanism, progression and locations of damages to the tunnels are assessed through a gradual increase in Permanent Ground Displacement (PGD). The ground surface deformations and strains, fault surface trace, fault scarp and the sinkhole caused by fault movement are observed here. These ground surface deformations are major threats to stability, safety and serviceability of the structures. According to the observations, the modeled tunnels are vulnerable to reverse fault rupture and but the functionality loss is not abrupt, and the tunnel will be able to tolerate some fault displacements. By monitoring the progress of damage states by increasing PGD, the fragility curves corresponding to each damage state were plotted and interpreted in related figures.

关键词: reverse fault rupture     continuous tunnel     geotechnical centrifuge     ground surface deformations     fragility curves    

Three-dimensional finite difference analysis of shallow sprayed concrete tunnels crossing a reverse faultor a normal fault: A parametric study

Masoud RANJBARNIA, Milad ZAHERI, Daniel DIAS

《结构与土木工程前沿(英文)》 2020年 第14卷 第4期   页码 998-1011 doi: 10.1007/s11709-020-0621-8

摘要: Urban tunnels crossing faults are always at the risk of severe damages. In this paper, the effects of a reverse and a normal fault movement on a transversely crossing shallow shotcreted tunnel are investigated by 3D finite difference analysis. After verifying the accuracy of the numerical simulation predictions with the centrifuge physical model results, a parametric study is then conducted. That is, the effects of various parameters such as the sprayed concrete thickness, the geo-mechanical properties of soil, the tunnel depth, and the fault plane dip angle are studied on the displacements of the ground surface and the tunnel structure, and on the plastic strains of the soil mass around tunnel. The results of each case of reverse and normal faulting are independently discussed and then compared with each other. It is obtained that deeper tunnels show greater displacements for both types of faulting.

关键词: urban tunnel     sprayed concrete     reverse fault     normal fault     finite difference analysis    

Highly hydrophobic oil−water separation membrane: reutilization of waste reverse osmosis membrane

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1606-1615 doi: 10.1007/s11705-022-2200-0

摘要: The increasing applications of seawater desalination technology have led to the wide usage of polyamide reverse osmosis membranes, resulting in a large number of wasted reverse osmosis membranes. In this work, the base nonwoven layer of the wasted reverse osmosis membrane was successfully modified into the hydrophobic membrane via surface deposition strategy including TiO2 and 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS), respectively. Various techniques were applied to characterize the obtained membranes, which were then used to separate the oil–water system. The optimally modified membrane displayed good hydrophobicity with a contact angle of 135.2° ± 0.3°, and its oil–water separation performance was as high as 97.8%. After 20 recycle tests, the oil–water separation performance remained more than 96%, which was attributed to the film adhesion of the anchored TiO2 and PFOTS layer on the surface. This work might provide a new avenue for recycling the wasted reverse osmosis membrane used in oily wastewater purification.

关键词: oil–water separation     wasted reverse osmosis membrane     hydrophobic modification    

Self-healing polyamide reverse osmosis membranes with temperature-responsive intelligent nanocontainers

《化学科学与工程前沿(英文)》 2023年 第17卷 第9期   页码 1183-1195 doi: 10.1007/s11705-022-2287-3

摘要: Improving the performance of reverse osmosis membranes remains great challenge to ensure excellent NaCl rejection while maintaining high water permeability and chlorine resistance. Herein, temperature-responsive intelligent nanocontainers are designed and constructed to improve water permeability and chlorine resistance of polyamide membranes. The nanocontainer is synthesized by layer-by-layer self-assembly with silver nanoparticles as the core, sodium alginate and chitosan as the repair materials, and polyvinyl alcohol as the shell. When the polyamide layer is damaged by chlorine attack, the polyvinyl alcohol shell layer dissolves under temperature stimulation of 37 °C, releasing inner sodium alginate and chitosan to repair broken amide bonds. The polyvinyl alcohol shell responds to temperature in line with actual operating environment, which can effectively synchronize the chlorination of membranes with temperature response and release inner materials to achieve self-healing properties. With adding temperature-responsive intelligent nanocontainers, the NaCl rejection of thin film composite membrane decreased by 15.64%, while that of thin film nanocomposite membrane decreased by only 8.35% after 9 chlorination cycles. Effective repair treatment and outstanding chlorine resistance as well as satisfactory stability suggest that temperature-responsive intelligent nanocontainer has great potential as membrane-doping material for the targeted repair of polyamide reverse osmosis membranes.

关键词: reverse osmosis     nanocontainer     self-healing     chlorine resistance     water permeability    

Mechanism of ethanol/water reverse separation through a functional graphene membrane: a molecular simulation

《化学科学与工程前沿(英文)》 2023年 第17卷 第3期   页码 347-357 doi: 10.1007/s11705-022-2246-z

摘要: Reverse-selective membranes have attracted considerable interest for bioethanol production. However, to date, the reverse-separation performance of ethanol/water is poor and the separation mechanism is unclear. Graphene-based membranes with tunable apertures and functional groups have shown substantial potential for use in molecular separation. Using molecular dynamics simulations, for the first time, we reveal two-way selectivity in ethanol/water separation through functional graphene membranes. Pristine graphene (PG) exhibits reverse-selective behavior with higher ethanol fluxes than water, resulting from the preferential adsorption for ethanol. Color flow mappings show that this ethanol-permselective process is initiated by the presence of ethanol-enriched and water-barren pores; this has not been reported in previous studies. In contrast, water molecules are preferred for hydroxylated graphene membranes because of the synergistic effects of molecular sieving and functional-group attraction. A simulation of the operando condition shows that the PG membrane with an aperture size of 3.8 Å achieves good separation performance, with an ethanol/water separation factor of 34 and a flux value of 69.3 kg∙m‒2∙h‒1∙bar‒1. This study provides new insights into the reverse-selective mechanism of porous graphene membranes and a new avenue for efficient biofuel production.

关键词: reverse separation     graphene membrane     ethanol/water separation     molecular simulation    

Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ

《环境科学与工程前沿(英文)》 2022年 第16卷 第4期 doi: 10.1007/s11783-021-1480-9

摘要:

• RED performance and stack resistance were studied by EIS and LSV.

关键词: Reverse electrodialysis     Electrochemical impedance spectroscopy     Concentration polarization     Spacer shadow effect    

Preparation of reverse osmosis membrane with high permselectivity and anti-biofouling properties for

《环境科学与工程前沿(英文)》 2022年 第16卷 第7期 doi: 10.1007/s11783-021-1497-0

摘要:

• Nanoparticle incorporation and anti-biofouling grafting were integrated.

关键词: Anti-biofouling grafting     Nanoparticle incorporation     Sterilization rates     Water flux     Water flux recovery    

Efficient production of hydrogen peroxide in microbial reverse-electrodialysis cells coupled with thermolytic

《环境科学与工程前沿(英文)》 2023年 第17卷 第9期 doi: 10.1007/s11783-023-1708-y

摘要:

● Appreciable H2O2 production rate was achieved in MRCs utilizing NH4HCO3 solutions.

关键词: Microbial reverse-electrodialysis cell     Hydrogen peroxide production     Ammonium bicarbonate     Electrolysis cell     Optimization    

Surface-tailoring chlorine resistant materials and strategies for polyamide thin film composite reverse

《化学科学与工程前沿(英文)》 2022年 第16卷 第5期   页码 564-591 doi: 10.1007/s11705-021-2109-z

摘要: Polyamide thin film composite membranes have dominated current reverse osmosis market on account of their excellent separation performances compared to the integrally skinned counterparts. Despite their very promising separation performance, chlorine-induced degradation resulted from the susceptibility of polyamide toward chlorine attack has been regarded as the Achilles’s heel of polyamide thin film composite. The free chlorine species present during chlorine treatment can impair membrane performance through chlorination and depolymerization of the polyamide selective layer. From material point of view, a chemically stable membrane is crucial for the sustainable application of membrane separation process as it warrants a longer membrane lifespan and reduces the cost involved in membrane replacement. Various strategies, particularly those involved membrane material optimization and surface modifications, have been established to address this issue. This review discusses membrane degradation by free chlorine attack and its correlation with the surface chemistry of polyamide. The advancement in the development of chlorine resistant polyamide thin film composite membranes is reviewed based on the state-of-the-art surface modifications and tailoring approaches which include the in situ and post-fabrication membrane modifications using a broad range of functional materials. The challenges and future directions in this field are also highlighted.

关键词: reverse osmosis     polyamide     thin film composite membranes     chlorine resistance     surface modification    

Winner determination problem with loss-averse buyers in reverse auctions

Xiaohu QIAN, Min HUANG, Yangyang YU, Xingwei WANG

《工程管理前沿(英文)》 2017年 第4卷 第2期   页码 212-220 doi: 10.15302/J-FEM-2017019

摘要: Reverse auctions have been widely adopted for purchasing goods and services. This paper considers a novel winner determination problem in a multiple-object reverse auction in which the buyer involves loss-averse behavior due to uncertain attributes. A corresponding winner determination model based on cumulative prospect theory is proposed. Due to the NP-hard characteristic, a loaded route strategy is proposed to ensure the feasibility of the model. Then, an improved ant colony algorithm that consists of a dynamic transition strategy and a Max-Min pheromone strategy is designed. Numerical experiments are conducted to illustrate the effectiveness of the proposed model and algorithm. We find that under the loaded route strategy, the improved ant colony algorithm performs better than the basic ant colony algorithm. In addition, the proposed model can effectively characterize the buyer’s loss-averse behavior.

关键词: reverse auction     loss aversion     winner determination     improved ant colony algorithm    

Performance of landfill leachate treatment system with disc-tube reverse osmosis units

WANG Baozhen, LIU Shuo, LIU Yanping, LI Xiujin

《环境科学与工程前沿(英文)》 2008年 第2卷 第1期   页码 24-31 doi: 10.1007/s11783-008-0024-x

摘要: Reverse osmosis system with the disc-tube module (DT-RO) was applied to treat landfill leachate on full scale at the Changshengqiao Sanitary Landfill, Chongqing City, China. In the first six-mouth operation phase, the treatment performance of DT-RO system had been excellent and stable. The removal rate of chemical oxygen demand (COD), total organic carbon (TOC), electrical conductivity (EC), and ammonia nitrogen (NH-N) reached 99.2–99.7%, 99.2%, 99.6%, and over 98%, respectively. The rejection of Ca, Ba, and Mg was over 99.9%, respectively. Suspended solid (SS) was not detected in product water. Effective methods had been adopted to control membrane fouling, of which chemical cleaning is of utmost importance to guarantee the long smooth operation of the DT-RO system. The DT-RO system is cleaned in turns with Cleaner A and Cleaner C. At present, the 1st stage cleaning cycle by Cleaner A and Cleaner C is conducted every 100 and 500 h, respectively, depending on raw the water quality.

关键词: chemical cleaning     product     organic     nitrogen     Effective    

Fertilizer drawn forward osmosis as an alternative to 2nd pass seawater reverse osmosis: Estimation of

《环境科学与工程前沿(英文)》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1428-0

摘要:

• The boron concentration in diluted DS can satisfy the irrigation water standard.

关键词: Fertilizer drawn forward osmosis (FDFO)     Boron removal     Specific energy consumption (SEC)     Seawater reverse osmosis (SWRO)     Irrigation water production    

Formation of reverse micelles in supercritical carbon dioxide and its thermodynamics

WEN Zhen, DANG Zhi, ZHU Zhixin, ZONG Minhua

《化学科学与工程前沿(英文)》 2007年 第1卷 第3期   页码 283-286 doi: 10.1007/s11705-007-0051-3

摘要: The solubilization behavior of methyl orange as a solvation probe in multiple systems composed of supercritical carbon dioxide, surfactants and co-solvents, is studied. It is concluded that some surfactants, such as sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) and isooctyl phenol polyethoxylate (TX-10), could form reverse micelles in supercritical carbon dioxide under the action of butanol. The formation of reverse micelles is a spontaneous process thermodynamically. Specifically for the nonionic surfactant TX-10, the formation of reverse micelles is dependent on the entropy increase in the system, while for the anionic surfactant AOT, the micellization is mainly dominated by the increase in enthalpy at higher temperatures, but by the increase in entropy at lower temperatures.

关键词: micellization     surfactant AOT     TX-10     sulfosuccinate     solubilization    

Basic research on machinery fault diagnostics: Past, present, and future trends

Xuefeng CHEN, Shibin WANG, Baijie QIAO, Qiang CHEN

《机械工程前沿(英文)》 2018年 第13卷 第2期   页码 264-291 doi: 10.1007/s11465-018-0472-3

摘要:

Machinery fault diagnosis has progressed over the past decades with the evolution of machineries in terms of complexity and scale. High-value machineries require condition monitoring and fault diagnosis to guarantee their designed functions and performance throughout their lifetime. Research on machinery Fault diagnostics has grown rapidly in recent years. This paper attempts to summarize and review the recent R&D trends in the basic research field of machinery fault diagnosis in terms of four main aspects: Fault mechanism, sensor technique and signal acquisition, signal processing, and intelligent diagnostics. The review discusses the special contributions of Chinese scholars to machinery fault diagnostics. On the basis of the review of basic theory of machinery fault diagnosis and its practical applications in engineering, the paper concludes with a brief discussion on the future trends and challenges in machinery fault diagnosis.

关键词: fault diagnosis     fault mechanism     feature extraction     signal processing     intelligent diagnostics    

Feature extraction from slice data for reverse engineering

ZHANG Yingjie, LU Shangning

《机械工程前沿(英文)》 2007年 第2卷 第1期   页码 25-31 doi: 10.1007/s11465-007-0004-z

摘要: A new approach to feature extraction for slice data points is presented. The reconstruction of objects is performed as follows. First, all contours in each slice are extracted by contour tracing algorithms. Then the data points on the contours are analyzed, and the curve segments of the contours are divided into three categories: straight lines, conic curves and B-spline curves. The curve fitting methods are applied for each curve segment to remove the unwanted points with pre-determined tolerance. Finally, the features, which consist of the object and connection relations among them, are founded by matching the corresponding contours in adjacent slices, and 3D models are reconstructed based on the features. The proposed approach has been implemented in OpenGL, and the feasibility of the proposed method has been verified by several cases.

关键词: feasibility     corresponding     B-spline     pre-determined tolerance     extraction    

标题 作者 时间 类型 操作

Centrifuge experiments for shallow tunnels at active reverse fault intersection

Mehdi SABAGH, Abbas GHALANDARZADEH

期刊论文

Three-dimensional finite difference analysis of shallow sprayed concrete tunnels crossing a reverse faultor a normal fault: A parametric study

Masoud RANJBARNIA, Milad ZAHERI, Daniel DIAS

期刊论文

Highly hydrophobic oil−water separation membrane: reutilization of waste reverse osmosis membrane

期刊论文

Self-healing polyamide reverse osmosis membranes with temperature-responsive intelligent nanocontainers

期刊论文

Mechanism of ethanol/water reverse separation through a functional graphene membrane: a molecular simulation

期刊论文

Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ

期刊论文

Preparation of reverse osmosis membrane with high permselectivity and anti-biofouling properties for

期刊论文

Efficient production of hydrogen peroxide in microbial reverse-electrodialysis cells coupled with thermolytic

期刊论文

Surface-tailoring chlorine resistant materials and strategies for polyamide thin film composite reverse

期刊论文

Winner determination problem with loss-averse buyers in reverse auctions

Xiaohu QIAN, Min HUANG, Yangyang YU, Xingwei WANG

期刊论文

Performance of landfill leachate treatment system with disc-tube reverse osmosis units

WANG Baozhen, LIU Shuo, LIU Yanping, LI Xiujin

期刊论文

Fertilizer drawn forward osmosis as an alternative to 2nd pass seawater reverse osmosis: Estimation of

期刊论文

Formation of reverse micelles in supercritical carbon dioxide and its thermodynamics

WEN Zhen, DANG Zhi, ZHU Zhixin, ZONG Minhua

期刊论文

Basic research on machinery fault diagnostics: Past, present, and future trends

Xuefeng CHEN, Shibin WANG, Baijie QIAO, Qiang CHEN

期刊论文

Feature extraction from slice data for reverse engineering

ZHANG Yingjie, LU Shangning

期刊论文