在国际智能结构健康监测学会（ISHMII）3月份的会刊上，该学会主席F. Ansari教授报道了我中心博士生严珺凡等五位来自于不同国家的研究生近期的科研进展情况。全文转载如下（原文见http://www.icontact-archive.com/foSoxV_DrpD5DPDAzLgBwIeRU-i5yZig?w=3）：
Meet the Future - Research Stories from Five Rising Scholars
The future of our profession is well-represented by the graduate students in our universities who apply a skilful mix of curiosity and knowledge to the most pressing technical and application issues related to CSHM and construction. Most are engineers, many in civil engineering. Still others are pursuing or have degrees in computer or electrical engineering, materials or even mechanical engineering. As students, they chase data in the field and work industriously in our labs to build our body of knowledge.
I am pleased to join with Professors Shi Bin, Doug Thomson, Asif Usmani, Su Taylor, and ZS Wu to introduce four Ph.D. students and one M.Sc. student around the world who are undertaking research in SHM. Each was nominated by a professor as a solid example of a young researcher whose work is impressive. We recognize the variety of experience they and their peers bring to their universities and our ISHMII community. In the future, we will profile additional students.
In China, Yan Junfan is conducting his Ph.D. research in environmental geotechnical engineering, distributed optical fiber sensing technology and application and engineering monitoring and health diagnosis with Professors Shi Bin and Wang Baojun of the Department of Geo-engineering and Geo-informatics, Nanjing University. Early in his career, Junfan is part of a team receiving two patents. His research covers information representation and state identification in the case of a major engineering catastrophe that focuses on the evolution of a landslide and on the development and demonstration of optical fiber sensing technology for monitoring geological disasters. He is creating monitoring devices and conducting indoor model tests of the slope stability of the Three Gorges reservoir bank using distributed optical fiber sensing.
Through the Center for Engineering Monitoring with Opto-Electronic Sensing, Junfan has become well-informed on designing and characterizing the capabilities of monitoring equipment that merges the advantages of optical fiber sensing technology with BOTDA and FBG distributed optical fiber sensing technology. His recent study of the sensing performance of a copper-based fiber optic sensing belt for distributed engineering monitoring produced successful results. The belt, designed and constructed by the research team, underwent a stretching calibration test and a three-points bending test on an I-beam to assess its measurement performance, with BOTDA and BOTDR used to measure the extension and bending strain.
Junfan’s findings demonstrated a good agreement between the measured data and the real strains. This confirmed that the copper-based fiber optic sensing belt can be used as a distributed fiber optic sensor in civil and geo-structural safety and health monitoring, and that it has a strong future with a wide number of potential applications. In addition, this test showed the belt’s cost-effectiveness, a point of interest to engineers and managers.
At Scotland’s University of Edinburgh, Amar Seeam is an unusual Ph.D. student. This is not just because he is earning his degree part-time, but because of the choice of his field – outside the world of massive civil structures. Supervised by Professors David Laurenson and Asif Usmani, Amar’s extensive background emphasizes the assortment of academic and professional fields found among CSHM researchers, and holds an appointment as a Research Assistant in the Department of Electronic and Electrical Engineering at the University of Strathclyde. A mechanical engineer with MSc degrees in Information Technology and in System Level Integration and a Royal Society of Edinburgh/Scottish Enterprise Fellow, Amar has participated as a Knowledge Transfer Partnership Associate with a modular construction company in Scotland. There, he completed a project in the integration of building management and structural health monitoring systems for modular buildings. Put together, Amar’s interests naturally focus on computer networking, building information modelling, embedded sensors and systems, smart homes, energy, and structural health monitoring.
He is currently researching the use of building simulation as a dynamic control tool for reducing energy consumption when integrated with building management systems as part of his Ph.D. program, and also researching non-intrusive methods and disaggregation techniques for energy monitoring in buildings. Amar has researched the application of building information modelling as a tool that can be used for monitoring energy and structural health in terms of risk management and mitigation. Additionally, Amar is interested in developing low cost systems for monitoring and control using affordable micro-controller and embedded systems, and he has developed novel sensors for structural health monitoring using combined power and data transmission technologies. Above: (Top) Amar Seeam applies building information modeling. (Left) Research results shown on the chart.
In Northern Ireland, the integrity of the engineering heritage together with the safety of workers on site was a motivating force in the research of Myra Lydon, a Ph.D. student at Queens University Belfast, School of Planning, Architecture and Civil Engineering, where she is supervised by Professor Su Taylor. Their team’s research is well-recognized, in part, due to the historic reference in its name: Titanic Dry Dock.
Thompson Dry Dock’s 1905 lock gate and dock were closed in 2001, markedly unsafe due to corrosion. For the restoration, the original lock gate was enclosed in a temporary cofferdam to enable the construction of a permanent concrete sea defense wall and the dock was dewatered to allow the construction to proceed.
To do this, a support structure was required in the caisson chamber to transfer water pressure loads from the sheet piling to the dock walls without affecting the original lock gate structure. The real-time monitoring during the dewatering ensured the integrity of the transfer structure through the highest loading conditions. Myra calibrated and installed fiber Bragg strain sensors with temperature compensation on the support in order to monitor the change in strain. Optical sensors were used as they are corrosion resistant in a marine environment (particularly in the tidal zone), have temperature compensation at the same location and can function under water. This was significant as Myra carried out the monitoring in the 12 hour period before dewatering to record tidal data and continued monitoring during dewatering and for 12 hours after the caisson was dried.
The results were interpreted to confirm whether it was safe to allow personnel to enter the chamber to work on the restoration of the Thompson Dry Dock. It was safe.
In Canada, Khalada Perveen is an advanced M.Sc. student supervised by Professor Doug Thomson in the University of Manitoba, Department of Electrical and Computer Engineering. After earning her degree in electronics and communication engineering, Khalada served as a faculty member in the Department of Electrical and Electronic Engineering at Stamford University of Bangladesh. Her research describes the development and applications of a wireless corrosion potential sensor that is installed in a reinforced concrete structure to monitor the corrosion rate of the reinforcement steel. Khalada recognizes the growing interest in structural health monitoring applications as corrosion is a major problem for civil infrastructure and a leading factor in infrastructure deterioration. Techniques such as half-cell potential can be used to periodically monitor corrosion, but are difficult to reliably interpret, and wired systems are expensive to install, with long-term reliability issues due to wire corrosion.
The sensor on which Khalada and the team is working is based on a coil resonator whose resonant frequency changes due to the corrosion potential applied across a parallel varactor diode. They monitor the corrosion potential externally using an inductively coupled coil. In these tests, a low cost coupled coil corrosion potential sensor is embedded in fresh and salt mixed mortar to replicate the new and built-in structure that will monitor the corrosion behavior of reinforcement steel. Test results show that this sensor can accurately measure corrosion potentials with a resolution of less than 10 mV; it will detect corrosion at the initiation stage before observable corrosion has taken place. One of the important outcomes of this research is that the sensor is simple in design, inexpensive and passive, a desirable battery-less option for long-term corrosion monitoring that can be widely deployed for civil structure health monitoring. Above: (Top) Khalada Perveen, a member of International Association of Engineers (IAENG). (Left) Monitoring devices with coil resonator.
Finally, we return to China where Ph.D. candidate Yongsheng Tang is conducting research on the development of smart fiber-reinforced polymer (FRP) materials and structures that use distributed optical fiber sensing technology. A student in the Southeast University Department of Civil Engineering, Nanjing, Yongsheng is supervised by Professor ZS Wu. Yongsheng proposed a new type of smart FRP material that is based on the distributed optical fiber sensing technology and a protocol for manufacturing. The parameters of this material, including the least gage length and bond length, have been confirmed by experiments as successfully optimizing the long-gage optical sensors. The distributed optical fiber sensing core can be prepared with some package crafts. This includes braiding the fibers of material around the optical fiber to strengthen the final product, covering some tubes for making the long-gage sensor and controlling the pre-strain of the optical fiber. His research demonstrates how this can be accomplished with high precision.
Yongsheng has also investigated the strain and temperature sensing properties of the smart Basalt FRP rebar through experiments, such as linearity, repeatability, and precision, among other tests. In these experiments, he compared some key factors, such as the rebar size and fiber content, to illustrate their influence on the sensing performance of the embedded optical fiber. Meanwhile, he also investigated the elastic modulus and ultimate strength of the material. As part of his Ph.D. research Yongsheng has also developed a new damage detection method based on a macro-strain concept and verified its effectiveness experimentally. He has applied his method in a field test including applying it to the signal processing of some bridges, including the Wayne Bridge, New Jersey, as part of the international bridge study program led by Rutgers University. Above: Yongshen Tang, on the right, with a colleague while conducting a field test on the Wayne Bridge.
For further information about these remarkable students and their research, please feel free to contact any of them, directly. Yan Junfan - yjf880326@126.com; Amar Seeam - a.seeam@ed.ac.uk; Myra Lydon - mlydon01@qub.ac.uk; Khalada Perveen - umpervee@cc.umanitoba.ca; and Yongsheng Tang - tys19821025@gmail.com.
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