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Fiber Optic Sensing Technologies for Bridge Health Monitoring

Fiber Optic Sensing Technologies for Bridge Health Monitoring. A Review of Fiber Optic Sensing Technologies for Bridge Health Monitoring Abstract The application of structural health monitoring (SHM) systems in bridge infrastructures has lead to the enhanced safety, durability, reliability and cost-effective management of these structures. In the last two decades, a significant number of innovative sensing technologies based on optical fiber sensors have been applied for SHM due to their inherent distinctive advantages, such as small size, light weight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability. Fiber optic-based monitoring systems use quasi-distributed and continuously distributed sensing techniques for real time measurement and long term assessment of physical and engineering properties of bridges. This allows for early stage damage detection and characterization, leading to timely remediation and prevention of catastrophic failures. The purpose of this article is to review the current state-of-the-art of fiber optic sensing/monitoring technologies, including the basic principles of various optical fiber sensors, novel sensing and computational methodologies, and the practical application status of this technology for bridge health monitoring. Additionally, application of these technologies to monitor temperature, inclination, stresses, strain measurements, vehicle speeds and weights, and corrosion and cracking of reinforced and prestressed concrete structures of bridges will also be discussed. 1. Introduction Bridges play a vital role in advancing nation’s transport infrastructure. Loss of lives and financial losses have been caused by bridge failures (Li, Ou, and Zhou 2009). Bridges deteriorate with age and early detection of damage helps in timely remediation preventing catastrophic failures. Several bridges built decades ago are now subjected to various load patterns and environmental changes, which can cause localized distress and if not corrected can result in bridge failure. Therfore, structural health monitoring is necessary to ensure bridge safety. SHM refers to the procedure used to assess the condition of structures over a period of time using appropriate sensors to monitor their performance, and measurements yeilded by these sensors can help in early damage detection and risk assessment, thus increasing reliability, safety and efficiency of the structures. Recent advancements in fiber optic sensing (FOS) techniques offer unique advantages for i) long-term monitoring, ii) large distances (in the range of several kilometers), and iii) early detection of risks associated with damage of civil infrastructures. One of the distinct advantages of FOS is their ability to measure physical quantities (such as displacements, inclination and strains) continuously distributed over the full length of the fiber. In order to measure distributed strains over the full length of a fiber, several techniques have been proposed, including Fiber Bragg Gratings (FBG), scattering based distributed sensors following the principle of optical reflectometry and interferometry (Fabry-Perot (FP)) based sensors. These sensing systems are easy to install, capable of autonomous operation, and are designed to measure strains and other physical parameters induced due to mechanical and thermal stresses. The objective of this paper is to review the current state-of-the-art of FOS technologies and its application for monitoring bridge infrastructures and its associated components. 2. Fiber Optic Sensing Technologies A fiber optic sensing system consists of a light transmitter, a receiver, an optical fiber, a modulator element, and a signal processing unit. These systems are based on the variations of physical characteristics of optical fibers such as light intensity, frequency/wavelength, phase, and polarization, which are sensitive to various external signals/stimuli. Based on the sensing principle, fiber optic sensors can be categorized into different types as illustrated in the following sections. 2.1 Fiber Bragg Grating (FBG) Sensors FBG sensors consist of varied refractive indices in the core of optical fiber (Peters 2009). According to Bragg’s law, a beam of white light is written in the FBG sensor, and when the light from the broadband source passes through the grating at a particular wavelength, the Bragg wavelength is reflected which is related to the grating period, as shown in Figure 1. The Bragg wavelength can be calculated by equation 1, where eff is the effective index of refraction and Λ is the grating period. Bragg wavelength could be shifted with the variations of temperature, strain, and vibration due to the surrounding environment. The variation of the Bragg wavelength can be obtained by equation 2, where Δ is the strain variation, Δ is the temperature change, is the coefficient of the thermal expansion, is the thermooptic coefficient, and is the strain-optic coefficient. Figure 1. Working principle of FBG Sensor λB=2neffΛ (1) ΔλB=λBα ξΔT (1–pe)Δε (2) 2.2 Optical Time-Domain Reflectometry (OTDR) Sensors An OTDR based sensor is capable of distributed sensing over the length of an optical fiber with a specific refractive index (Barnoski et al. 1977). When a light pulse at a particular wavelength propagates along the optical fiber, the sensor can locate the position of the interaction according to the propagation time, as shown in Figure 2. The OTDR-based distributed sensor measures the change in the properties of the light along the entire optical fiber by measuring the time of flight of the returned pulses. The Brillouin optical time domain reflectometer (BOTDR) is one of the well-known distributed fiber optic sensors that is based on the Brillouin scattering. Due to the advantage of being capable of measuring continuous strain and temperature over a long distance, the BOTDR has been widely applied in distributed monitoring of large-scale civil structures. Figure 2. Working principle of OTDR Sensor 2.3 Fabry-Perot Interferometry (FPI) Sensors FPI sensors follow the principle of Fabry-Perot interferometry (Yoshino et al. 1982), which is the intensity of the interference signals illuminated between two parallel reflecting interfaces as shown in Figure 3. The interference pattern shifts according to the optical path change and depending on the length of FP cavity. The length can be affected by pressure change and temperature variation (e.g. environmental change). For FPI sensors, the intensity of interference signal is given by equation 2, where I1 and I2 are the reflection at the cavity reflecting interfaces, φ is the initial phase of the interference, Λ is the optical wavelength and Z is the optical path difference (Rao 2006). Figure 3. Working principle of FPI Sensor I=2I1I2I1I2×cos⁡(4πZ/λ ϕ) (3) 3. Applications of Fiber Optic Sensing Technologies for Bridge Health Monitoring Bridges are critical infrastructures which are vital for daily transportation activities and its health conditions have always been a concern for the bridge owners, contractors and government. Moreover, bridges are subjected to various environmental and operational loadings and continuous real time monitoring is necessary for system identification, damage detection, safety condition assessment, and structural performance prediction. Due to unique and distinctive advantages, fiber optic sensors have been meticulously explored as an effective tool for monitoring various structural components of bridges (decks, towers, stay cables, suspenders, girders, piers, piles, and abutments), for measuring different physical parameters such as strains, temperatures, accelerations, deflections/displacements, cracks, and corrosion detailed in the following sections. 3.1 Comprehensive Bridge Monitoring Numerous fiber optic based SHM systems have been developed and effectively deployed on various bridges worldwide. Barbosa et al. developed novel weldable strain and temperature sensors based on FBG and installed on circular pedestrian steel bridge for loading tests and evaluate the real time variations of the axial forces in its main structural elements (Barbosa et al. 2008). Mehrani et al. developed a remote sensing system utilizing fiber optic sensors based on FPI for condition assessment of bridge by monitoring its behaviour under traffic loads (Mehrani, Ayoub, and Ayoub 2009). The system was deployed for field instrumentation on a bridge in Florida, USA, during its construction stage. The accuracy of the sensors was estimated by static and dynamic testing under heavy truck loads and validated through 3-dimensional analytical finite element analysis. Kerrouche et al. developed a low cost and compact FBG-based monitoring system incorporating a scanning Fabry Perot filter for strain measurement (Kerrouche et al. 2009). The performance of the system was validated in a field test by installing sensors into CFRP reinforcement rods of a damaged bridge. Rodrigues et al. developed an FBG-based system with embedded displacement and strain transducers for long-term monitoring of structural performance of concrete bridges which was applied to a concrete bridge (Rodrigues et al. 2012). Glisic and Inaudi developed a novel method using distributed fiber optic technology based on Stimulated Brillouin scattering for integrity monitoring of bridges to detect cracks and local deformations (Glisic and Inaudi 2012). The method utilized a glass fiber reinforced thermoplastic composite tape integrated with polyimide-coated optical fibers and deployed on-site by attaching on concrete slab and steel girders of a 1000m long bridge in order to detect and localize cracks and unusual short-term and long-term strain changes. Mokhtar et al. designed a compact temperature compensated FBG based strain sensors sandwiched between two polypropylene slabs and installed on the paragrid and on the surfaces of a flexi-arch bridge to monitor strain and temperature (Mokhtar et al. 2012). Surre et al. developed an optical fiber sensor system based on FBG for long-term strain monitoring and condition assessment of a redundant 50-year-old concrete footbridge (Surre, Sun, and Grattan 2013). Yau et al. developed a simple, inexpensive, and practical method based on FBG strain and tilt sensors to measure vertical displacements of bridges (Yau et al. 2013). An inclination approach and a curvature approach using these sensors was employed to determine vertical displacements with various support conditions and varying stiffness (EI) along the spans of the bridge which is further validated through numerical simulations. Zhao et al. developed multiscale fiber optical sensing network by combining distributed optical fiber sensing technology based on Brillouin scattering and the FBG sensing technology for bridge strain monitoring with local high precision and distributed high precision respectively (Zhao et al. 2012). Minardo et al. demonstrated stimulated Brillouin scattering based distributed FOS for monitoring strain distribution along a 44.4 m long road bridge (Minardo et al. 2012). The optical fibers were installed along the supporting beams and the results yielded a spatial resolution of 3 m and a strain resolution of 15 µε. Xu et al. investigated field monitoring of a 1108 m suspension bridge using integrated distributed FOS based on high resolution Brillouin time domain analysis system with differential pulse-width pair (DPP) technique (Xu et al. 2016). The system monitored distributed strains along the whole length of the bridge with up to 0.05 m spatial resolution, and 0.01 m/point sampling interval. 3.2 Bridge Cables and Suspenders Monitoring Cables and suspenders are one of the most critical structural components of a bridge that readily suffer from fatigue damage, corrosion damage, and their coupled effects (Lan and Li 2009). Li et al. developed a self-sensing smart stay cable assembled with FBG strain and temperature sensors incorporated into a glass fibre reinforced polymer (GFRP) bar (Li, Ou, and Zhou 2009). The system was inserted into the hollows of steel wires and fixed with the steel cable to monitor deformation, stress and fatigue within the cable. The efficiency of the developed smart stay cable was proved through field application by evaluating the induced stresses and fatigue accumulative damage of a stay cable bridge in China (Li, Zhou, and Ou 2011). He et al. designed a cable force monitoring system by combining local high precision FBG sensors and full scale distributed BOTDR sensing technique in one single optical fiber and installed along with the steel cable wire (He, Zhou, and Jinping 2013). The cable force obtained from the developed sensor agreed well with theoretical value with relative error less than ± 5%. Hu et al. conducted an indirect measurement study for cable force monitoring by developing a FBG vibration sensor for online monitoring of the cable vibration characteristics (Hu et al. 2017). The sensor was deployed on Tongwamen bridge, China and the monitored vibration frequency was converted into cable force according to the theory of string vibration in order to achieve an indirect measurement of bridge cable force. 3.3 Railway Bridge Monitoring Scott et al. evaluated a FOS system based on commercially available FBG for strain monitoring in railway bridges by conducting laboratory tests under the bridge loading conditions (Scott et al. 2013). The experimental results showed that the FBG strain sensor can obtain good agreement compared with electrical resistance strain gauges. Wei et al. designed a FOS system based on FBG to monitor the bridge strengthening effect accurately by measuring vertical deflection, dynamic load moment and transverse vibration of the railroad bridge (Wei et al. 2013). Wei concluded that the developed system can be extended to large span and arch bridges. Yoon et al. utilized Brillouin optical correlation domain analysis (BOCDA) technology to monitor the longitudinal strain on the rail and girders of a railway bridge during train passage in real time (Yoon et al. 2016). The performance of BOCDA in measuring distributed strain was comparable with conventional strain gauges. Yu et al. developed an SN model of a typical heavy haul railway bridge of China high speed railway and designed a FBG-electrical based multi-sensor for fatigue load monitoring (Yu et al. 2018). The multi-sensor consisted of a fiber-reinforced polymer optical FBG, an electrical resistance strain gauge, a linear variable displacement transducer, and an accelerometer. 4. Conclusions This paper provides a brief review of various fiber optic sensing technologies employed for structural health monitoring of bridges. Bridges are an integral part of society’s infrastructure and reliable sensing methods are necessary to monitor them and ensure their safety and efficiency. FOS technology has proven to be a suitable method for this purpose and possesses several distinct advantages over other monitoring methods. The simplicity, immunity to EMI and corrosion, distributed long-range sensing, non-invasive sensing (due to the miniature size of FOS), and signal sensitivity of FOS systems enable them to become a popular and effective structural health monitoring approach. However, certain challenges and limitations of FOS such as fiber handling issues, bending losses, cross-sensitivity between thermal strain and mechanical strain exists and still needs to be addressed. In conclusion, FOS have shown a promising potential over other conventional methods in the monitoring of bridge infrastructure. 5. References Barbosa, C, N Costa, LA Ferreira, FM Araújo, H Varum, A Costa, C Fernandes, and H Rodrigues. 2008. ‘Weldable fibre Bragg grating sensors for steel bridge monitoring’, Measurement Science and Technology, 19: 125305. Barnoski, M_K, M_D Rourke, SM Jensen, and RT Melville. 1977. ‘Optical time domain reflectometer’, Applied Optics, 16: 2375-79. Glisic, Branko, and Daniele Inaudi. 2012. ‘Development of method for in-service crack detection based on distributed fiber optic sensors’, Structural Health Monitoring, 11: 161-71. He, Jianping, Zhi Zhou, and Ou Jinping. 2013. ‘Optic fiber sensor-based smart bridge cable with functionality of self-sensing’, Mechanical Systems and Signal Processing, 35: 84-94. Hu, Dongtao, Yongxing Guo, Xianfeng Chen, and Congrui Zhang. 2017. ‘Cable force health monitoring of Tongwamen Bridge based on fiber bragg grating’, Applied Sciences, 7: 384. Kerrouche, A, WJO Boyle, T Sun, and KTV Grattan. 2009. ‘Design and in-the-field performance evaluation of compact FBG sensor system for structural health monitoring applications’, Sensors and Actuators A: Physical, 151: 107-12. Lan, CM, and H Li. 2009. “Stay cable vehicle live load effects analysis based on structural health monitoring data.” In ICCES: International Conference on ComputationalFiber Optic Sensing Technologies for Bridge Health Monitoring
Los Angeles Southwest College The Importance of Voting Discussion.

PART 1 Discuss why there is a renewed attack on voting rights since November 2020 election. Discuss why the “Browning of America” scares the GOP and the GOP constituency, in light of the changes in Congressional politics. Discuss the definition of “HR1” and “HR4” and its potential. Explain the purpose of the Civil Rights Act of 1964 and the correlating Voting Rights Act of 1965. Be very specific about the Supreme Courts rationale which now requires new legislation to correct their decision in 2013. Explain fully in your discussion what the Court changed which rendered the Voting Rights Act ineffective. Review Rubric for guidance.This Discussion should be about two or three paragraphs (400+ words). Responses to classmates should be about one paragraph(125+ words).You are required to post 3 times;( your initial post and your response to two other classmates). Be sure to start your posts with your full name. You will be required to post before replying. -10 points A Answer8-8.5 points B Answer7-7.5 points C Answer6-6.5 points D Answer0-5.5 points F Answer• Focus on topic is clear and definite• Excellent use of ideas and concepts• Excellent use of critical thinking skills• Excellent use of sentence structure to conveyargument• Excellent use of other resources in supporting yourresponse • Very good development of topic• Ideas and concepts are presented clearly• Writing structure is well organized• Argument is logical and intelligent• Good use of critical thinking skills• Good use of other resources in supporting yourresponsePART 2 After viewing the entire documentary and reading Chapter 15, write an essay showing the disparity facing African Americans protesting the injustices seen in the documentary(at the end of the 19th Century and the Start and during the 20th Century). In your introduction describe the meaning of the title and the collection process of gathering evidence the author uses to reveal the atrocities. Give eight specific cases the author shows how and why slavery was reestablished. Using Chapter 15 show how the Black communities individually and collectively responds in the fight against injustice….in other words how are these cruelties protested and investigated. Cite specific protagonist like Monroe Trotter, W.E.B. Du Bois, and organizations like The Chicago Defender. The goal is to assess your ability to explain and utilize the information given in the class thus far. Your essay is three to five paragraphs. It probably wise to write a draft first.What Are the 5 Parts of an Essay?Introduction. The first part of your essay will be the introduction and it should begin by telling the reader specifically what topic your essay is addressing. …First Body Paragraph. …Second Body Paragraph. …Third Body Paragraph. …Conclusion.RubricWriting Essay Content RubricWriting Essay Content RubricCriteriaRatingsPtsThis criterion is linked to a Learning OutcomeEvidence of Critical Thinking5 ptsExcellentExcellent use of critical thinking with quality support and constructive ideas4 ptsVery GoodVery good use of critical thinking with quality support and constructive ideas3 ptsGoodGood use of critical thinking with quality support and constructive ideas2 ptsNeeds ImprovementFocus on topic is unclear and show some knowledge of material1 ptsPoorNo critical thinking with little support of ideas5 ptsThis criterion is linked to a Learning OutcomeDemonstration of knowledge and understanding of Topic5 ptsExcellentFocus on topic is very clear and definite and shows knowledge and understanding of concepts and material4 ptsVery GoodClear and definite focus on topic with a clear understanding of concepts and material3 ptsGoodFocus on topic is average with a mediocre understanding of material2 ptsNeeds ImprovementFocus on topic is unclear and show some knowledge of material1 ptsPoorFocus on topic is poor and shows little knowledge of material5 ptsThis criterion is linked to a Learning OutcomeStructure and Development of Ideas5 ptsExcellentVery Strong and reasonable ideas with new concepts that stimulate discussion4 ptsVery GoodStrong and reasonable ideas wit new concepts that stimulate the discussion3 ptsGoodStrong and somewhat reasonable ideas to contribute to the discussion2 ptsBelow AverageSomewhat reasonable ideas that stimulate the discussion1 ptsPoorPoor ideas contributed to the discussion5 pts
Los Angeles Southwest College The Importance of Voting Discussion

Managing people ( Lesson 5)

Managing people ( Lesson 5). I’m stuck on a Management question and need an explanation.

Lesson 5

Chapter 9: Building Capabilities for Change
Compose a paper that addresses the following:
Based on the information contained in Chapter 9, identify the capabilities required to lead and manage people through change effectively. How can these capabilities be acquired?
Please provide detailed support for your positions.
Requirements:

12-point Times New Roman; double spaced; and page numbering.
Please be sure to answer the entire question to receive maximum credit for this assignment.
Use and include information from the weekly course content and outside sources to support the conclusions contained in the paper.
Be cognizant of spelling, punctuation, and grammar.
All sources should be cited in proper APA format (in-text citations and a reference list).

Upon completion, upload your assignment in Word format to Moodle.
Managing people ( Lesson 5)

Arthur C. Clarke’s “The Star” Analytical Essay

term paper help Literary works including short stories, novels, poems and narratives provide us with lenses through which we can see and understand human nature and various cultural, social, and political aspects of our society which are critical to our societal well-being. They are a mirror through which a society can attain self realization more so in relation to its desired destiny in terms of social, political and economic development. Academically, they are usually a creative and constructive way of criticizing and attacking evils such as corruption, impunity, gender violence, and discrimination among others which are understandably a stumbling block to realization of societal dreams in the eyes of the wise people and intellectuals, as well as political leaders, of good will. Due to their critical contribution towards progress of a society authors should strive to be clear in their writings so that readers of different intellectual and educational caliber can understand what they are trying to articulate through their works. The purpose of this paper is to discuss theme of religion versus science in Arthur C. Clarke’s short story titled “The Star” published in 1955 which won him Hugo Award in 1956. Religion versus science Human beings are inherently curious beings who have always endeavored to comprehend not only themselves in terms of their origin, existence and destiny but also to understand the cause of the universe and everything therein since the very humble beginnings of human civilizations. A long side his physical and cultural evolution religious, traditional and scientific theories have been put forward during different epochs of the history of humankind which attempts to explain the origin of the universe and everything found in it, as well as the destiny of humanity. Currently, religious theories and the scientific evolution theory put forward by Sir. Get your 100% original paper on any topic done in as little as 3 hours Learn More Charles Darwin during the peak of scientific revolution in 19th century are the most popular in virtually all communities of the world in terms of explaining the origin of the universe, living organisms and humanity’s fate. However, there is an outcry and great concern particularly from the western clergy that religion is losing its influence up on people’s life especially in Western societies. Arthur C. Clarke’s short story titled “The Star” is a perfect representation of humanity’s grapple with the puzzle of whether it is religion or science that holds the right key to solutions regarding mysteries of this universe, fate of humanity, as well as remedies to perpetual social, political and economic problems-some of which are catastrophic-facing human societies. It shows perfectly how scientific discoveries can impact both positively and negatively up on our religious beliefs like in the case of the chief astrophysicist leading the group of explorers in “The Star” who was a Jesuit priest and who suffered a serious crisis of faith brought about by some undisclosed event during the expedition to the remote star system. Even though there are scientists who have managed to successfully balance the confrontation of scales between religious philosophies and science, a considerable number of scientists probably because of being overwhelmed by reality about complexity of the universe that is revealed through scientific endeavors ever since renaissance have dismissed the idea of God entirely. In other words, complexities of the universe and human life brought to light by scientific discoveries have made religious teachings about universe and life appear too simple and superficial to be true or worth believing to a considerable number of scientists. These explains the line of division between and among the group of explorers coming back from expedition narrated about in Arthur C. Clarke’s fictional masterpiece- “The Star”. Conclusion Surprisingly there are many scientists of no mean reputation both in western societies and other parts of the world who have appreciated the fact that science without religion is lame and religion without science is blind in real life. We will write a custom Essay on Arthur C. Clarke’s “The Star” specifically for you! Get your first paper with 15% OFF Learn More They recognize convincingly that human societies requires an emancipating religion and objective science in order to deal fairly well with problems facing them as they strive to attain self realization regarding their place and purpose of existence in this universe.

Improving Global Software Development Project Performance Simulation Discussion

Improving Global Software Development Project Performance Simulation Discussion.

Read the description of the two options in the Module 8 folder. This week, complete Scenario C.Part 1: Perform the simulation multiple times and try changing input parameters to obtain a better score and complete the scenario with better results. In doing so, you will benefit from running the sessions using different options and trying different action items to experience various project challenges. After completing the simulation session, save a screen shot of the confirmation page showing your total score.Part 2: Write to three-page paper describing the scenario you completed, the intent of the simulation, and your lessons learned. Identify a minimum of four what-if assessments that resulted in obtaining a better score and completing the scenario with better results. Use scholarly resources to support your findings.Be sure to organize your writing properly and include the following:Cover pageIntroductionBody of your work with headings and subheadingsAnalysis and recommendationsConclusionList of referencesAppendix A – Screen shot of confirmation page showing your best simulation score.Consult the Sample Paper template (Links to an external site.) for more information on how to organize the paper.Support your assignment with a minimum of three scholarly references. The CSU Global Library is a good place to locate these sources. The written section should follow the CSU Global Writing Center (Links to an external site.).Requirements: 3 pages
Improving Global Software Development Project Performance Simulation Discussion

Broward Community College Health Promotion and Disease Prevention Paper

Broward Community College Health Promotion and Disease Prevention Paper.

I’m working on a writing discussion question and need support to help me study.

Healthy People 2030 and NursingFaith-Based NursingReview Healthy People 2030. Identify objectives that are amenable to parish nurse intervention.Describe how faith communities can contribute to the accomplishment of these national health objectives and accomplish the goal of improving the health of the public.How can nurses working in the community form partnerships with parish nurses and faith communities?How would such partnerships be beneficial?Collaboration at the Local, State, and Federal LevelsDescribe the roles of your local and state health departments in the accomplishment of healthcare promotion and goals.How do their goals of health promotion meet the objective of Healthy People 2030?How could nurses in the public health setting help clients to modify unhealthy behaviors at the primary and secondary prevention levels?Please provide an example for each prevention level.Add references please
Broward Community College Health Promotion and Disease Prevention Paper

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