Sensors for deformation monitoring of large civil infrastructures

In the maintenance of large infrastructures such as dams, bridges, railways, underground structures (tunnels, mines) and others, monitoring of deformations plays a key role in maintaining the safety serviceability conditions and for mitigating any consequences due to ageing factors and possible structural failures. [...]

A survey of sag monitoring methods for power grid transmission lines

The transmission line is a fundamental asset in the power grid. The sag condition of the transmission line between two support towers requires accurate real-time monitoring in order to avoid any health and safety hazards or power failure. In this paper, state-of-the-art methods on transmission line sag monitoring are thoroughly reviewed and compared. Both the direct methods that use the direct video or image of the transmission line and the indirect methods that use the relationships between sag and line parameters are investigated. Sag prediction methods and relevant industry standards are also examined. Based on these investigation and examination, future research challenges are outlined and useful recommendations on the choices of sag monitoring methods in different applications are made

Monitoring of Overhead Polymer Core Composite Conductors Under Excessive Mechanical Loads Using Fiber Bragg Grating Sensors

This combined experimental and numerical study addresses mechanical effects associated with static and dynamic loading of novel High Temperature Low Sag (HTLS) transmission line polymer core composite conductors. The developed methodology was successfully applied to ACCC® to explain the complex failure mechanisms associated with combined bending and tension loading. Furthermore, the use of Fiber Bragg Grating (FBG) sensors was investigated for the first time to monitor the ACCC® design during installation and in-service. Transverse low-velocity impacts to the ACCC® conductor having either free or constrained end conditions and large axial tensile loads were performed. It was identified that the most damaging condition under impact is when the conductor had free ends and was thus subjected to severe bending. The experimental work performed using an original approach was supported by non-linear static and dynamic finite element analyses. For the multiaxial case of rods subjected to bending and axial tension, the axial stresses were predicted analytically and numerically with the likely failure initiating locations identified based on the theoretical composite compressive strengths. The initiating damage mechanisms change from compressive to tensile modes as axial tension increases. It has been shown for the first time that the natural presence of fiber misalignment must be considered in the failure analysis of hybrid composite rods as it can significantly reduce bending strength and influence the location of damage initiation. It has been demonstrated that FBG sensing is a viable technique for in-service monitoring of ACCC® conductors subjected to a variety of static and impact situations. Under static and low energy/velocity conditions, surface mounted sensors can accurately measure strains both on the bare rods and inside the conductors. The tests on the fullscale conductors under low energy impact also showed that the sensors can identify the location and magnitude of impact with a high degree of sensitivity. These results, combined with the intrinsic properties of optical sensors and fibers, indicate the FBG sensors could be especially useful in the monitoring of low and high energy impact events in-service. Finally, an evaluation of using of embedded FBG sensors inside the hybrid composite core of ACCC® is presented

Icing Effects on Power Lines and Anti-icing and De-icing Methods

Icing on power lines may lead to compromise safety and reliability of electric supply network. Prolong icing can lead to power breakdown and collapse of towers. Since power transmission lines are mostly overhead and could face the direct impact of icing, and it is one of the main challenges faced by power distribution companies in cold regions. When the ice accretion crosses the safety limit then deicing action can be carried out. We can find number of deicing methods that are used in different parts of the world. However, all of these deicing techniques have their own advantages and disadvantages on implementation. It is one of the most difficult as well as dangerous process to perform deicing on power lines. If a fault is detected and that has been occurred due to icing or during routine maintenance, extra care must be taken in order to ensure safety of the personals when performing de-icing of lines. However, as technology evolved, new ways and techniques are adopted with the help of sensors that give quick feedback to control room in the national grid via wireless communication network for real time action. In the thesis we have discussed atmospheric icing impacts on power lines in the cold regions across the world. A literature review has been done for anti-icing and deicing methods that are currently adopted in the power distribution network. Methods that are used against ice buildups have also been analyzed. This work also shows the impacts of icing and deicing techniques presently adopted, and also throws light on their pros and cons during maintenance operations. It provides an overview of the evolving technology trends that are practiced to ensure the availability of existing power transmission system in cold climate regions

Bridges Structural Health Monitoring and Deterioration Detection Synthesis of Knowledge and Technology

INE/AUTC 10.0

Fiber Bragg Grating Based Sensors and Systems

This book is a collection of papers that originated as a Special Issue, focused on some recent advances related to fiber Bragg grating-based sensors and systems. Conventionally, this book can be divided into three parts: intelligent systems, new types of sensors, and original interrogators. The intelligent systems presented include evaluation of strain transition properties between cast-in FBGs and cast aluminum during uniaxial straining, multi-point strain measurements on a containment vessel, damage detection methods based on long-gauge FBG for highway bridges, evaluation of a coupled sequential approach for rotorcraft landing simulation, wearable hand modules and real-time tracking algorithms for measuring finger joint angles of different hand sizes, and glaze icing detection of 110 kV composite insulators. New types of sensors are reflected in multi-addressed fiber Bragg structures for microwave–photonic sensor systems, its applications in load-sensing wheel hub bearings, and more complex influence in problems of generation of vortex optical beams based on chiral fiber-optic periodic structures. Original interrogators include research in optical designs with curved detectors for FBG interrogation monitors; demonstration of a filterless, multi-point, and temperature-independent FBG dynamical demodulator using pulse-width modulation; and dual wavelength differential detection of FBG sensors with a pulsed DFB laser

Monitoring of State Transitions in Extreme Environment Application Materials Using Fiber Bragg Grating Sensors

By embedding both a single fiber Bragg grating (FBG) sensor and a thermocouple (TC) during the manufacturing for extreme environment applications of certain classes of materials such as metals and polymers, a novel in-situ approach was developed to precisely monitor their entire manufacturing processes. This novel monitoring technique was able to identify many characteristic points during the curing of room and high-temperature epoxies and the solidification processes of metal alloys composed of tin and bismuth which were selected in this research purely for verification purposes. Some of the characteristic points identified for the epoxies were: (i) the gel point, (ii) the start of cure, (iii) the end of cure, (iv) the end of the manufacturing cycle, etc. For the tin/bismuth alloys, the technique was used for the first time to (i) identify the beginning and end of solidification and (ii) to construct the phase diagram of the alloys. It was demonstrated that the FBG sensor-based technique is better suited than the existing TC-based technique to detect the phase transitions of the alloys. The solidification process of water was also monitored and compared to the solidification process of the metals. The water solidification research was subsequently extended to simulate ice formation on transmission line conductors and to determine if the newly proposed FBG/TC method could be used as an ice monitoring method in service. A novel heat balance approach was presented to identify the degree of cure for the epoxies and to estimate the end of solidification in the alloys. The heat balance approach was verified using the Flory-Stockmayer theory for identifying the gel point in polymers. By using the FBG measurements and a combination of linear elastic models, a novel, yet straightforward approach was presented to determine the residual stresses in a single fiber/polymer composite. Further, multiple factors that impact the calculation of axial strain evolution using fiber Bragg grating (FBG) sensors were thoroughly investigated and verified by analyzing the cooling of the epoxies, the tin/bismuth alloys, and ice. The proposed monitoring technique could significantly improve the current capability to (i) measure the degree of cure of polymers, (ii) determine the residual strains and stresses in single fiber composites with polymer and metal matrices, (iii) assess the strain evolution during the solidification of metals, (iv) recreate the phase diagrams of metal alloys, (v) estimate stresses in solidified metal parts, (vi) monitor icing and deicing on transmission lines, and many others. Since the specimen preparation is straightforward, the proposed method can be routinely practiced, and the measurements can be completely automated. The techniques could provide a much-needed tool for rapid but accurate assessment of materials for extreme environment applications

Aeronautical engineering: A continuing bibliography with indexes (supplement 318)

This bibliography lists 217 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1995. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

International Conference on Civil Infrastructure and Construction (CIC 2020)

This is the proceedings of the CIC 2020 Conference, which was held under the patronage of His Excellency Sheikh Khalid bin Khalifa bin Abdulaziz Al Thani in Doha, Qatar from 2 to 5 February 2020. The goal of the conference was to provide a platform to discuss next-generation infrastructure and its construction among key players such as researchers, industry professionals and leaders, local government agencies, clients, construction contractors and policymakers. The conference gathered industry and academia to disseminate their research and field experiences in multiple areas of civil engineering. It was also a unique opportunity for companies and organizations to show the most recent advances in the field of civil infrastructure and construction. The conference covered a wide range of timely topics that address the needs of the construction industry all over the world and particularly in Qatar. All papers were peer reviewed by experts in their field and edited for publication. The conference accepted a total number of 127 papers submitted by authors from five different continents under the following four themes: Theme 1: Construction Management and Process Theme 2: Materials and Transportation Engineering Theme 3: Geotechnical, Environmental, and Geo-environmental Engineering Theme 4: Sustainability, Renovation, and Monitoring of Civil InfrastructureThe list of the Sponsors are listed at page 1