12 results on '"Quqa, Said"'
Search Results
2. Crack identification using electrical impedance tomography and transfer learning.
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Quqa, Said, Landi, Luca, and Loh, Kenneth J.
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ELECTRICAL impedance tomography , *ELECTRICAL resistance tomography , *ARTIFICIAL neural networks , *POPULATION transfers , *SENSOR networks , *SPRAY painting - Abstract
Sensing skins and electrical impedance tomography constitute a convenient and inexpensive alternative to dense sensor networks for distributed sensing in civil structures. However, their performance can deteriorate with the aging of the sensing film. Guaranteeing high identification performance after minor lesions is crucial to improving their ability to identify structural damage. In this paper, electrical resistance tomography is used to identify the crack locations in nanocomposite paint sprayed onto structural components. The main novelty consists of using crack annotations collected during visual inspections to improve the crack identification performance of deep neural networks trained using simulated datasets through transfer learning. Transfer component analysis is employed for simulation‐to‐real information transfer and applied at a population level, extracting low‐dimensional domain‐invariant features shared by simulated models and structures with similar geometry. The results show that the proposed method outperforms traditional approaches for crack localization in complex damage patterns. [ABSTRACT FROM AUTHOR]
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- 2023
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3. Phase Change Memories in Smart Sensing Solutions for Structural Health Monitoring.
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Quqa, Said, Antolini, Alessio, Franchi Scarselli, Eleonora, Gnudi, Antonio, Lico, Andrea, Carissimi, Marcella, Pasotti, Marco, Canegallo, Roberto, Landi, Luca, and Diotallevi, Pier Paolo
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PHASE change memory , *STRUCTURAL health monitoring , *SMART structures , *CENTRAL processing units , *INFRASTRUCTURE (Economics) , *NONVOLATILE memory - Abstract
Smart devices for structural health monitoring provide edge computing capabilities to reduce wireless transmission and, thus, power consumption. Although effective algorithms have been proposed in the last few decades, traditional microcontrollers require heavy data flow between the memory and the central processing unit that involves a considerable fraction of the total energy consumption. Phase change memory has recently emerged as an attractive solution in the field of resistive nonvolatile memory for analog in-memory computing, which is a valid approach to avoid data being conveyed among distinct elaboration units. However, it has never been envisaged in structural health monitoring applications. As this technology is still in an embryonic state, several challenges related to nonlinearities and nonidealities of the memory elements and the energy expenditure related to the memory reprogramming process may undermine its usage. In this paper, the application of a novel identification approach for civil infrastructures is investigated using phase change memories. The main computational core of the presented algorithm, consisting of one-dimensional convolutions, is particularly suitable for implementations involving analog in-memory computing, thus showing the great potential of this technology for structural health monitoring applications. The test unit is an embedded phase change memory provided by STMicroelectronics and designed in 90-nm smart power bipolar complementary metal-oxide-semiconductor (CMOS)-double-diffused metal-oxide-semiconductor (DMOS) technology with a Ge-rich Ge-Sb-Te alloy for automotive applications. Experimental results obtained for a viaduct of an Italian motorway support the efficacy of the method. Moreover, the influence of nonidealities on the outcomes of damage identification based on both dynamic and quasi-static structural parameters is examined. [ABSTRACT FROM AUTHOR]
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- 2022
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4. Instantaneous identification of densely instrumented structures using line topology sensor networks.
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Quqa, Said, Landi, Luca, and Diotallevi, Pier Paolo
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SENSOR networks , *PARAMETER identification , *STRUCTURAL health monitoring , *INTELLIGENT sensors , *TOPOLOGY , *DATA transmission systems , *WIRELESS sensor networks - Abstract
Summary: In this paper, a new strategy for vibration‐based structural health monitoring is proposed, specifically designed for smart sensors with edge computing capabilities organized in a line topology. This solution is aimed at maximizing resource optimization and enables the identification of modal parameters even for large or densely instrumented structures, where star‐topology monitoring systems are typically unsuitable. In particular, an efficient data management procedure is proposed to reduce data transmission, thus improving efficiency and minimizing maintenance interventions for battery replacement in wireless applications. The maximum volume of transmitted data can be selected by the user, based on the specific requirements of the network. Although the considerable reduction of data size, the proposed approach enables accurate estimation of the structural parameters in challenging scenarios where other techniques generally fail. Modal parameters are identified in an online fashion, enabling near real‐time detection and localization of early damage. Applications to a real case study instrumented with a dense sensor network show the effectiveness of the proposed approach and the possibility of localizing structural defects in slightly damaged civil structures. [ABSTRACT FROM AUTHOR]
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- 2022
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5. On the Use of Singular Vectors for the Flexibility-Based Damage Detection under the Assumption of Unknown Structural Masses.
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Quqa, Said, Landi, Luca, and Diotallevi, Pier Paolo
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VECTORS (Calculus) , *MATRICES (Mathematics) , *PARAMETER estimation , *FACTORIZATION , *DAMAGE models - Abstract
The main purpose of this work is to investigate the usability of easily obtainable parameters instead of the modal traditional ones, in the context of a flexibility-based damage detection procedure, under the assumption of unknown structural masses. To this aim, a comparison is made between two different approaches: the first involves the calculation of the flexibility matrix by using traditional modal parameters, such as natural frequencies and modal vectors, normalized to unitary values, while the second involves the use of singular vectors, obtained through a simple matrix factorization. The modal parameters and the singular vectors necessary for the implementation of the damage detection procedure are evaluated through two different techniques: the Eigensystem Realization Algorithm and a wavelet-based procedure, for which a variant is proposed by introducing the energy reassignment concept into the original algorithm. Through the latter approach, in particular, it is possible to obtain a high number of singular vectors even in the case of reduced availability of sensors. The study is performed under the assumption of nonstationary excitation, in order to achieve general results, and the effectiveness of the procedures is evaluated through simulated tests regarding different structural schemes. [ABSTRACT FROM AUTHOR]
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- 2018
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6. Integrating flexibility-based curvature with quasi-static features induced by traffic loads for high-resolution damage localization in bridges.
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Quqa, Said and Landi, Luca
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TRUSS bridges , *STRUCTURAL health monitoring , *CURVATURE , *HILBERT-Huang transform , *KALMAN filtering , *FILTER banks , *SENSOR networks - Abstract
• Curvature is identified from dynamic and quasi-static acceleration response. • Filtering and empirical mode decomposition provide curvature influence lines. • Sparse modal parameters and dense influence lines are fused using Kalman filter. • The system state represents dense and robust curvature estimate. • Monitoring the state evolution allows high-resolution damage localization. Curvature is one of the most popular damage-sensitive features in vibration-based structural health monitoring applications, typically calculated from identified modal features. While the relevant strategic or historical importance of bridges may justify dense sensor networks, a limited budget is generally assigned to monitor "minor" viaducts, thus involving inexpensive devices or extremely sparse sensing solutions. Modal parameters can only be obtained at instrumented locations. Thereby, damage assessment methods based on identified features typically have a low spatial resolution, especially when using low-cost monitoring setups with a modest number of sensing devices. This paper proposes an original identification method for the curvature of bridges based on sparse acceleration measurements that can be collected using standard accelerometers. The raw acceleration signal is processed through a particular filter bank that extracts dynamic and quasi-static signal components. The first components are employed to identify modal parameters, from which sparse yet robust estimates of the structural curvature are retrieved. On the other hand, the quasi-static acceleration generated by the structural deflection induced by traffic load is used to identify the curvature influence lines of the bridge, which are fused with modal estimates using a Kalman filter. The state variable of the analyzed system, representing a dense curvature profile of the structure subjected to concentrated loads, can be used as a damage-sensitive feature for high-resolution damage localization. The method is applied to a steel truss bridge subject to different damage configurations. [ABSTRACT FROM AUTHOR]
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- 2023
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7. The value of monitoring a structural health monitoring system.
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Giordano, Pier Francesco, Quqa, Said, and Limongelli, Maria Pina
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STRUCTURAL health monitoring , *CORROSION fatigue , *DECISION theory , *STATISTICAL decision making , *EMERGENCY management - Abstract
• Structural health monitoring systems can be damaged and provide altered data. • The value of information framework is here extended to account for sensor faults. • The uncertainty in assessing the state of the monitoring systems is accounted for. • Knowing the state of the monitoring system increases the value of information. Structural Health Monitoring (SHM) systems are adopted to acquire timely and continuous data on the state of civil structures, aerospace vehicles, and industrial machines, which deteriorate due to slow processes, such as corrosion and fatigue, and shock events, including natural and man-made disasters. The components of SHM systems themselves are exposed to deterioration after their installation; thereby, they might provide altered information to decision-makers. To account for this issue, Sensor Validation Tools (SVTs) have been developed to give insight into the actual condition of the SHM systems. In the last decade, researchers have exploited the Value of Information (VoI) from Bayesian decision theory to quantify the benefit of the information provided by an SHM system, implicitly assuming that it is working correctly when interrogated. The benefit of the information provided by SVTs on the state of an SHM system has never been investigated. This paper addresses this topic and extends the classical VoI framework to quantify the additional benefit brought by the information on the state of the SHM system to the decision problems it is meant to support. A numerical analysis, as well as a methodology demonstration on a real bridge, are presented to discuss the framework. [ABSTRACT FROM AUTHOR]
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- 2023
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8. Shared micromobility-driven modal identification of urban bridges.
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Quqa, Said, Giordano, Pier Francesco, and Limongelli, Maria Pina
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FOOTBRIDGES , *STRUCTURAL health monitoring , *SENSOR placement , *MODE shapes , *MOTOR vehicle springs & suspension , *ELECTRIC bicycles - Abstract
Recent research in Indirect Structural Health Monitoring (ISHM) uses the dynamic response of instrumented vehicles to carry out "drive-by" monitoring of bridges. These vehicles are generally cars or trucks instrumented with different types of sensors. However, some urban bridges are inaccessible to regular vehicles. Also, cars and trucks have non-negligible weight and suspension systems that may affect the collected vibration data. Stiff, light, and standardized shared micromobility vehicles, such as bicycles and electric kick scooters, have never been explored for ISHM purposes. This paper proposes an innovative and automatic ISHM strategy based on the data collected by smartphones temporarily installed on shared micromobility vehicles. An identification procedure suitable for cloud computing is proposed to extract the dynamic parameters of bridges without needing any sensor deployment, becoming particularly appealing for monitoring a densely built environment at a territorial scale. The methodology is applied to a real footbridge in Bologna (Italy). • Crowdsourcing from human-powered vehicles is first employed for bridge monitoring. • Cloud-based platforms can gather and process crowdsourced data automatically. • The Kalman filter is used to fuse smartphone data and identify modal parameters. • A smartphone deployed on a city bike is employed to collect IMU and GPS data. • The first natural frequency and absolute mode shape of a footbridge are identified. [ABSTRACT FROM AUTHOR]
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- 2022
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9. Automatic identification of dense damage-sensitive features in civil infrastructure using sparse sensor networks.
- Author
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Quqa, Said, Landi, Luca, and Diotallevi, Pier Paolo
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SENSOR networks , *AUTOMATIC identification , *BRIDGES , *EXPRESS highways , *STRUCTURAL health monitoring , *EMERGENCY management , *PARAMETER identification - Abstract
Widespread monitoring of bridges is yet rarely employed at a territorial level due to the high costs of monitoring systems. However, the aging of civil infrastructures, combined with the growing traffic demand, poses the need for a simple and automatic tool that helps emergency management. In this paper, an integrated algorithm for the identification of dynamic and dense quasi-static structural features exploiting moving vehicles is proposed. Filtering raw acceleration structural responses, triggered by passing vehicles, enables the identification of modal parameters and curvature influence lines. The procedure can be implemented efficiently as its main computational core consists of convolutions. The definition of a curvature-based damage index leads to accurate localization and quantification of structural anomalies using few sensors. The proposed procedure is tested on three viaducts of the Italian A24 motorway. Moreover, a numerical model is studied to evaluate the potentialities of the strategy for damage localization. • An integrated method to identify modal parameters and influence lines is proposed. • Dense structural features of bridges are identified by filtering acceleration data. • Quasi-static features can be directly employed as dense damage indicators. • Accurate damage localization can be achieved efficiently, using few sensors. • Numerical and experimental case studies show the potential of the method proposed. [ABSTRACT FROM AUTHOR]
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- 2021
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10. Modal assurance distribution of multivariate signals for modal identification of time-varying dynamic systems.
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Quqa, Said, Landi, Luca, and Paolo Diotallevi, Pier
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TIME-varying systems , *DYNAMICAL systems , *MULTIVARIATE analysis , *FALLOW deer , *WHITE noise , *IMAGE segmentation - Abstract
• A new time–frequency representation is proposed for multivariate signals. • Instantaneous modal identification is achieved for linear time-varying systems. • The method provides good results for crossing and vanishing modes. • Narrow-band components in the excitation do not compromise the quality of results. • Numerical and experimental case studies show the potential of the method proposed. Most time–frequency representations (TFRs) and signal analysis methods used for the identification of dynamic systems through non-parametric techniques are based on univariate signals. However, combining the information obtained from different sensors to investigate the overall behavior of the monitored structure is not trivial, as different recordings may show different features. Moreover, methods based upon the analysis of the energy density distribution in the time–frequency plane generally suffer from problems related to crossing and closely-spaced modes. In this paper, a new time–frequency representation of multivariate and multicomponent signals based on the modal assurance criterion (MAC) is presented. The analysis of the modal assurance distribution (MAD) thus obtained enables the extraction of decoupled modal responses, which can then be used to evaluate the instantaneous modal parameters of time-varying systems. To this end, a decomposition algorithm based on modal assurance (DAMA) is proposed, employing the watershed segmentation of the MAD. The results for two case studies, a finite element model and a full-scale experimental benchmark, are shown, considering both the original MAD and two enhanced versions, here proposed to improve its readability. The results are compared with those obtained from modern and widely used techniques, showing the promising efficacy of the proposed method for signals with time-varying frequency and amplitude, even in the presence of narrow-band disturbances and white noise, as well as with vanishing modes. [ABSTRACT FROM AUTHOR]
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- 2021
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11. The value of seismic structural health monitoring for post-earthquake building evacuation.
- Author
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Giordano, Pier Francesco, Iacovino, Chiara, Quqa, Said, and Limongelli, Maria Pina
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STRUCTURAL health monitoring , *BUILDING evacuation , *EARTHQUAKE aftershocks , *EFFECT of earthquakes on buildings , *BUSINESS losses , *HEALTH literacy , *EMERGENCY management - Abstract
In the aftermath of a seismic event, decision-makers have to decide quickly among alternative management actions with limited knowledge on the actual health condition of buildings. Each choice entails different direct and indirect consequences. For example, if a building sustains low damage in the mainshock but people are not evacuated, casualties may occur if aftershocks lead the structure to fail. On the other hand, the evacuation of a structurally sound building could lead to unnecessary financial losses due to business and occupancy interruption. A monitoring system can provide information about the condition of the building after an earthquake that can support the choice between several competing alternatives, targeting the minimization of consequences. This paper proposes a framework for quantifying the benefit of installing a permanent seismic structural health monitoring (S2HM) system to support building evacuation operations after a seismic event. Decision-makers can use this procedure to preventively evaluate the benefit of an SHM system and decide about the worthiness of its installation. [ABSTRACT FROM AUTHOR]
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- 2022
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12. Instantaneous modal identification under varying structural characteristics: A decentralized algorithm.
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Quqa, Said, Landi, Luca, and Paolo Diotallevi, Pier
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STRUCTURAL health monitoring , *IDENTIFICATION , *NONLINEAR operators , *FILTER banks , *INTELLIGENT sensors - Abstract
• Instantaneous identification of time-varying modal parameters is pursued. • A two-step output-only algorithm and a signal-adaptive variant are presented. • The algorithm is suitable for emerging decentralized systems based on smart sensors. • The algorithm is applied to a real bridge structure for damage identification. • The results demonstrated the effectiveness and usability of the proposed procedure. One of the latest trends in structural health monitoring involves the use of wireless decentralized sensing systems, developed to reduce costs and speed up the whole monitoring process. The main purpose of this paper is to present a novel decentralized procedure for the instantaneous modal identification of time-varying structures, also suitable in the presence of environmental variations and non-stationary ambient excitation. In particular, a modal assurance criterion (MAC)-based clustered filter bank (CFB) is obtained, capable of decomposing structural responses into modal components for the evaluation of time-varying natural frequencies and modal shapes through a nonlinear energy operator. The proposed algorithm is relatively simple and usable with low-cost smart sensing systems, as it requires low computational effort and works with few data at a time. To prove the effectiveness of the presented method, a simulated near-real-time modal identification procedure has been performed on a full-scale bridge under progressive damage scenarios. The estimated modal parameters have then been used for damage diagnosis. The results reveal a good correspondence between identified modal parameters and reference values, showing also promising outcomes for both damage detection and localization. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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