Damage Index Values Research Articles

A rapid damage assessment framework for regular RC frame structures under external explosions

Local damage of the structural members and even progressive collapse of structures occurred in terrorist or accidental explosions, but there are few unified frameworks of integrating the member damage into the structural damage for rapid assessment against blast loads. To fill this gap, a framework is proposed for engineering practice to rapidly assess damage levels of regular reinforced concrete (RC) frame structures under external explosions, in which the structural damage level is eventually determined with only two inputs: scaled distance and structural redundancy. A regular 5-story RC frame structure subjected to external explosions is adopted as an example to illustrate the proposed framework. Firstly, damage indexes of structural members are formulated under far-field explosions or close-in explosions, and the structural damage index is further derived through the weighted integration of the damage indexes of structural members. Subsequently, the damage modes and collapse processes of the designed RC frame structure are simulated under different explosion scenarios, and the energy-based damage indexes for assessing structures against blast loads are developed and validated. Through numerical results of 23 case studies, the structural damage assessment formula as a function of scaled distance and structural redundancy is derived through regress analysis, and on the other hand, two key threshold values of the energy-based damage indexes are introduced to classify the structural damage levels (minor, moderate and severe levels). Finally, the structural damage index is correlated to the energy-based damage index through curve-fitting to determine the corresponding threshold values of structural damage index as well, and the effectiveness of the damage assessment framework is further validated. The results show that the proposed damage assessment framework can rapidly and accurately assess the damage levels of the regular RC frame structures under external explosions, and the deviation between the predicted damage indexes and the numerical results are 4.11 %–9.52 %.

Efficacy of PZT Sensors Network Different Configurations in Damage Detection of Fiber-Reinforced Concrete Prisms under Repeated Loading.

Real-time structural health monitoring (SHM) and accurate diagnosis of imminent damage are critical to ensure the structural safety of conventional reinforced concrete (RC) and fiber-reinforced concrete (FRC) structures. Implementations of a piezoelectric lead zirconate titanate (PZT) sensor network in the critical areas of structural members can identify the damage level. This study uses a recently developed PZT-enabled Electro-Mechanical Impedance (EMI)-based, real-time, wireless, and portable SHM and damage detection system in prismatic specimens subjected to flexural repeated loading plain concrete (PC) and FRC. Furthermore, this research examined the efficacy of the proposed SHM methodology for FRC cracking identification of the specimens at various loading levels with different sensor layouts. Additionally, damage quantification using values of statistical damage indices is included. For this reason, the well-known conventional static metric of the Root Mean Square Deviation (RMSD) and the Mean Absolute Percentage Deviation (MAPD) were used and compared. This paper addresses a reliable monitoring experimental methodology in FRC to diagnose damage and predict the forthcoming flexural failure at early damage stages, such as at the onset of cracking. Test results indicated that damage assessment is successfully achieved using RMSD and MAPD indices of a strategically placed network of PZT sensors. Furthermore, the Upper Control Limit (UCL) index was adopted as a threshold for further sifting the scalar damage indices. Additionally, the proposed PZT-enable SHM method for prompt damage level is first established, providing the relationship between the voltage frequency response of the 32 PZT sensors and the crack propagation of the FRC prisms due to the step-by-step increased imposed load. In conclusion, damage diagnosis through continuous monitoring of PZTs responses of FRC due to flexural loading is a quantitative, reliable, and promising application.

Strengthening of reinforced concrete beam-column joints by means of fastened C-FRP ropes

The efficiency of using C-FRP ropes as external superficial reinforcement to strengthen beam-column connections in reinforced concrete structures with regard to seismic requirements is investigated experimentally. The method is an easy-to-apply, effective method for locally increasing the load-bearing capacity of beam-column connections in existing buildings. To strengthen the beam, external C-FRP ropes are placed in slots along each side of the beam at the top and bottom. The test results with test specimens on a scale of 1:1 in undamaged condition (JA0) and in strengthened condition after pre-damage (JA0b) are analysed and compared. From the comparative representation of the hysteresis reactions, it is concluded that the strengthened test specimens show an improved hysteresis reaction in all cases examined compared to the corresponding test specimens without strengthening. Comparisons of the damage index values and the equivalent viscous damping values obtained from the test results are also presented and commented on in order to enable objective and well-founded conclusions to be drawn. It can be concluded that the use of C-FRP ropes as external reinforcement is suitable as an efficient and easy-to-handle strengthening technique in all cases investigated.

Fragility analysis of high arch dam against far-field underwater blast

The security assessment of high arch dams is a significant topic that has been researched in recent years. It is troublesome to develop a security assessment for high arch dams under far-field underwater blasts because the high arch dam is a sophisticated statically indeterminate spatial shell structure, and the underwater blasting shock wave has the characteristics of a large peak value and high frequency. Hence, the fragility analysis of a 300-m-high arch dam against a far-field underwater blast based on the probabilistic method is conducted for safety evaluation with the index of downstream peak displacement (and Downstream Peak Displacement-Span ratio). The fragility analysis process of the high arch dam under the far-field underwater blast is proposed for the first time. The impact of foundation plasticity on the high arch dam under far-field underwater blast is discussed regarding dynamic response and damage patterns with the coupled acoustic-structural (CAS) method first. The damage limit states are presented based on different damage patterns and index values from enormous computational schemes. The fragility curves with different indexes of downstream peak displacement, upstream peak displacement, and damage volume ratio are also compared. The fragility curves of the high arch dam against the far-field underwater blast with different explosive distances of 50 to 200 m are established with the Artificial Neural Network method. The results demonstrate that the non-linear dynamic response and damage of the high arch dam under the far-field underwater blast are significantly influenced by the foundation plasticity, especially for vibration upstream and damage of the foundation face. The explosive situations with an explosive distance of 50–100 m and explosive weight of more than 12000 kg cause a greater threat to the security of the high arch dam with the probability of severe damage approaching 100 %. The explosive situations with an explosive distance of more than 150 m or explosive weight of less than 3000 kg have a small effect. The research results can be used as a reference when conducting safety assessments of high arch dams to blasting loads.

Amplitude Dispersion Compensation in Time-Reversed Lamb Waves for Enhanced Sensitivity in Damage Detection

In Lamb wave-based baseline-free damage detection employing the time-reversal method (TRM), the damage index (DI) is computed from the similarity between the main mode of the reconstructed signal obtained after the time-reversal process (TRP) and the input signal, both normalized. However, a perfect similarity with a zero DI value cannot be achieved for undamaged structures due to the amplitude dispersion of Lamb waves, which is not compensated in the TRP. Thus, a nonzero DI does not necessarily indicate the presence of damage. Even worse is the fact that the similarity and, therefore, the DI for the pristine structure depend on the probing frequency, making it difficult to estimate a unique threshold value of DI for damage identification. The imperfect reconstruction also significantly reduces the relative sensitivity of the DI to the presence of damage. In this article, we propose a method to compensate the amplitude dispersion in the main mode of the reconstructed signal for undamaged metallic plates to achieve a zero threshold of DI. First, the transfer function of the main mode of the reconstructed signal for an undamaged path (the path with the least DI for a network of sensing paths) is obtained by exciting the actuator with a broadband excitation and extracting the S0 and A0 modes from the forward response measured at the sensor. To compensate the amplitude dispersion in the TRP-generated main mode, the transfer function of the recorded signal of a path is divided by the transfer function of the main mode obtained for the undamaged path. A comprehensive numerical study shows that the DI computed with the compensated reconstructed signal has much higher sensitivity to damage than that without applying the proposed compensation at all frequencies, providing the flexibility to choose the probing frequency according to the desired damage size to be detected.

Quantification of Lamb Wave-based SHM technique through Ground Test under simulated flight environment for commercial airplane

This research introduces an advanced Structural Health Monitoring (SHM) methodology for in-service aircraft, with a specific focus on a case study involving 737NG Aft Pressure Bulkhead (APB) coupons. Aimed at achieving FAA first targeted application for FAA certification, the study leverages SMART layer technology to construct a sensor network, facilitating real-time damage assessment through Damage Index (DI) analysis for precise crack detection and localization. The core of our approach involves the utilization of DI values, obtained from the sensor data, to assess crack progression and pinpoint structural anomalies, highlighting the capability of SHM systems in enhancing maintenance efficiency and aircraft safety. Additionally, the Probability of Detection (PoD) analysis incorporated in this study assesses the SHM system's reliability, ensuring compliance with FAA standards. Our findings underscore the potential of SMART layer-based SHM systems in revolutionizing aircraft maintenance protocols by enabling proactive and accurate structural health assessments, particularly at the 4.5mm threshold. This case study not only demonstrates the feasibility of SHM in critical aircraft components but also sets a precedent for the wider application and development of SHM technologies in the aviation industry, promising to elevate safety standards and operational efficiency.

Automated Trucks’ Impact on Pavement Fatigue Damage

The automated truck’s steering system can potentially control its lateral movement (i.e., wander mode) within the lane. The controlled wander mode of automated trucks could affect the transverse loading distribution of the wheels and consequently influence pavement fatigue damage in the long term. This study examines the effects of potential wander modes on pavement fatigue damage, considering the effects of lane width, market penetration rate, flexible pavement layers’ thickness, and stiffness of the materials. This study uses a finite element model to calculate the flexible pavement response. The mechanistic–empirical method is used to compute the total fatigue damage index for a specific design period, incorporating the wander mode effect. Comparing the fatigue damage indices indicates that automated trucks could either reduce the damage index value from −1.41% to −7.05% (i.e., mitigator scenario) or increase it from +11.6% to +278.57% (i.e., aggravator scenario), depending on their deployment scenarios. Moreover, the findings show that using a uniform-wander mode instead of a zero-wander mode or increasing the thickness and stiffness of the pavement layers could effectively reduce the adverse effect of automated trucks on fatigue damage and reduce the damage indices from −0.06% to −42.95%. However, their impact is considerably influenced by market penetration rate and lane width.

The Lipid-Metabolism-Associated Anti-Obesity Properties of Rapeseed Diacylglycerol Oil.

To investigate the effects of rapeseed diacylglycerol oil (RDG) intake on lipid accumulation and metabolism in C57BL/6J mice, obese mice were fed a high-fat diet in which 45% of the total energy content came from RDG (RDGM group) or rapeseed triacylglycerol oil (RTGM group). This diet intervention was conducted for 12 weeks following the establishment of the obese mouse model. By the end of the experiment, the serum glucose levels of the mice in the RTGM and RDGM groups were 13.0 ± 1.3 mmol/L and 9.7 ± 1.5 mmol/L, respectively. Meanwhile, the serum triglyceride level in the RDGM group was 26.3% lower than that in the RTGM group. The weight-loss effect in the RDGM group was accompanied by a significant decrease in the white adipose tissue (WAT) index. The RDG intervention did not significantly change the antioxidant and anti-inflammatory properties of the rapeseed oil in vivo. The RDG diet improved the liver lipid metabolism abnormalities induced by a high-fat diet, leading to decreased liver damage index values (AST and ALT). Additionally, compared to that in the RTGM group, the expression of the adipogenic genes PPAR-γ and DGAT decreased in both the liver and intestine by 21.7% and 16.7% and by 38.7% and 47.2%, respectively, in the RDGM group. Further, most lipolytic genes in BAT showed no significant change after the RDG intervention. This implies that RDG regulates lipid metabolism by altering the expression of adipogenic genes in the liver, intestine, and adipose tissue, thereby reducing the accumulation of WAT. Furthermore, the RDG diet enhanced gut flora diversity, increasing the relative levels of unclassified Muribaculaceae and decreasing the levels of Dubosiella and Faecalibaculum in the mouse gut, potentially accelerating lipid metabolism. Thus, a three-month RDG diet intervention in obese mice exhibited benefits in regulating the somatotype, serum obesity-related indices, gut flora structure, and lipid metabolism in the adipose tissue, liver, and intestine.

Quantification of the out-of-plane loading fatigue response of bistable CFRP laminates using a machine learning approach

This study proposes data-driven machine learning models to predict the nonlinear load-displacement response in constant amplitude high-cycle fatigue loading of unsymmetric, cross-ply bistable carbon fiber reinforced polymer composites. Four selected ML models are trained on experimental fatigue data with eleven unique frequency, temperature, and boundary conditions combinations. Stiffness and damage index values, which serve as additional evaluation metrics, are calculated using the predicted load data. The models capture the nonlinear load response with acceptable error for in-domain experimental conditions. Model expandability demonstrates the sensitivity of machine learning models to training features but suggests an economical alternative to extensive fatigue experiments.

Investigating the seismic performance and developing the fragility curves of self-centering steel frames with augmented nonlinear viscous damping: A numerical simulation

This paper focuses on investigating the seismic performance of post-tensioned steel frames equipped with nonlinear viscous dampers. The aim is to increase the ductility and seismic energy dissipation capacity of these structures. Finite element (FE) models were created using the Abaqus software and validated against reference experimental data under cyclic loading. Two types of post-tensioned moment-resisting frames (PT-Frames) were developed: a conventional PT-Frame and a PT-Frame with two pairs of nonlinear viscous dampers acting as knee braces (each brace pair, contains two dampers connected in parallel, thus there are 4 dampers used in total). Various analyses, including modal analysis, cyclic loading, and incremental dynamic analysis (IDA), were conducted using earthquake records mentioned in FEMA P-695. Fragility curves were plotted based on the IDA results. The findings indicate that the augmented nonlinear viscous damping significantly increases the natural fundamental period of vibration in PT-Frames (133 % increase observed). It also enhances the absorption and dissipation of input seismic energy (800 % increase in cumulative dissipated seismic energy observed). Moreover, it reduces the probability of damage exceeding the damage index value for different performance levels (collapse prevention, life safety, and immediate occupancy) by average values of 115 %, 61.72 %, and 25.126 %, respectively. These improvements help mitigate damage to the structural components.

Enhancing Damage Detection in 2D Concrete Plates: A Comprehensive Study on Interpolation Methods and Parameters

In an era marked by increasing demands for stability and durability in construction, the importance of damage detection in concrete structures cannot be overstated. As these structures underpin the safety and longevity of vital assets, this paper embarks on a comprehensive exploration of methodologies to enhance precision and reliability in 2D concrete plate damage detection. By focusing on the interpolation of damage index values and leveraging the insights gained from energy loss analysis and the characterization of the time of arrival of signals, we address the pressing need for improved non-destructive damage detection techniques. Our study encompasses a range of simulation attempts, each involving various interpolation parameters, and systematically evaluates their performance. The culmination of this research identifies the most effective combination of techniques and parameters, leading to the best results in damage detection. This multidimensional investigation promises to provide valuable contributions to the field of structural health monitoring, benefiting both researchers and practitioners engaged in the evaluation of concrete structures.

Influence of near‐field ground motions with fling‐step and forward‐directivity characteristics on seismic response of stilted buildings in mountainous area

SummaryNear‐field ground motions with fling‐step and forward‐directivity characteristics contain large‐amplitude pulses in velocity history, causing severe damage to stilted buildings in mountainous areas. In this study, three groups of 20 near‐field ground motions with fling‐step and forward‐directivity characteristics and 10 far‐field ground motions were selected as seismic inputs. Nonlinear response history analysis (NLRHA) was performed on plane finite element models of two seven‐story stilted frame structures, one with steel braces in the stilted story and the other without steel braces in the slope direction. Structural seismic response obtained from NLRHA was discussed in terms of inter‐story drift ratio (IDR) and peak floor acceleration (PFA). In addition, damage to two structures was assessed using the modified Park–Huang damage model. The results show that stilted structures exhibit greater inter‐story ratios and damage index values under near‐field ground motions with fling‐step characteristics and forward‐directivity characteristics than far‐field ground motions, where the stilted story has the highest amplification ratio in both IDR and damage index among floors. Designers should pay sufficient attention to the influence of ground motions with fling‐step and forward‐directivity characteristics on seismic demands and damage to stilted structures. The peak inter‐story ratio and damage index of stilted structures with steel braces were significantly lower than that of stilted structures without braces, proving the validation of setting steel braces on reducing the seismic demands of stilted structures and improving structural seismic safety. Additional NLRHA performed using artificial pulses shows that the seismic response of stilted buildings is related to pulse periods of near‐field ground motions and the greatest seismic demands and damage are obtained when the pulse period is 1.5–1.6 times the fundamental period of the stilted building.

ANALISIS TINGKAT KERUSAKAN PANTAI AKIBAT BENCANA ABRASI DAN UPAYA PENANGANANNYA (PESISIR DESA STOWE BRANG)

Abrasion that occurs in Sumbawa Regency, Utan District, Stowe Brang Village is caused by wave factors, land characteristics which are generally in the form of peat, silt and sand are very vulnerable to erosion due to waves. In addition to natural factors, abrasion can also be blamed on human factors. The variables used in this study consist of 2 of them, namely: (1) Natural Factors, (2) Human Factors. The purpose of this study is to describe the coastal condition of Stowe Brang Village, Utan District, Sumbawa Regency. The analysis method used is Descriptive Analysis with a combination of Quantitative and Qualitative. To assess the condition of damage to coastal areas, it is necessary to survey the location of mangrove vegetation conditions, how far the coastline is to the pond, and the condition of the river estuary at the site. Furthermore, based on the value of the coastal damage index, the prioritization of handling refers to SE PU No. 11 of 2021. Based on the results of the analysis, there are several factors that affect the occurrence of abrasion at the study site, including factors still lack of vegetation on the beach, flat land slope factors, sandy beach type factors and the absence of coral reefs, sea wave factors that are large enough. To get wave plan data requires wind data for 10 years, tidal data, topographic data and bathymetry. Based on the results of data analysis, the wave height of the 10-year plan with the Gumbel method is 0.4 m. The form of handling efforts that can be done is the addition of mangrove vegetation and can also be done by building coastal protection constructions such as breakwater construction with plain concrete blocks

Evaluating the safety profile of calcineurin inhibitors: cancer risk in patients with systemic lupus erythematosus from the LUNA registry-a historical cohort study.

Previous studies have shown conflicting evidence regarding the incidence of cancer in patients with systemic lupus erythematosus (SLE) compared with that in healthy individuals. Calcineurin inhibitors (CNIs) such as cyclosporine and tacrolimus have been widely used to treat SLE; however, their effects on cancer risk remain unclear. We aimed to investigate the incidence of cancer in patients with SLE and determine the potential association between CNI use and cancer risk. The standardized incidence ratio (SIR) of cancer among patients with lupus in the Lupus Registry of Nationwide Institutions (LUNA) was calculated based on the age-standardized incidence rate of cancer reported by Japan's Ministry of Health, Labour and Welfare. We also examined the association between CNI exposure and cancer risk, while considering potential confounding factors. The analysis accounted for confounding variables such as age, sex, smoking history, maximum glucocorticoid dose, treatment history with cyclophosphamide, ongoing hydroxychloroquine, Systemic Lupus International Collaboration Clinics/American College of Rheumatology Damage Index (SDI) value (excluding cancer occurrence), comorbidity of diabetes mellitus, and smoking history. The study included 704 patients with SLE (625 females; 88.8%) with a median age of 44years [interquartile range (IQR) = 34-55] years. The median past maximum glucocorticoid dose was 40mg/day [IQR = 30-60mg/day], and the SDI at registration was 1 [IQR = 0-2]. Among the patients, 246 (35.1%) had smoking histories, and 38 (5.4%) experienced cancer complications. Gynecological malignancies accounted for 63.2% of all cancers. The SIR of cancer in the LUNA cohort was 1.08 (95% confidence interval [CI] = 0.74-1.43). No statistically significant risks of cancer were found in relation to CNI treatment history; the odds ratio using multiple logistic regression was 1.12 (95% CI = 0.42-3.00), the risk ratio using standardization was 1.18 (95% CI = 0.47-2.16), and the risk ratio using inverse probability weighting was 1.8 (95% CI = 0.41-4.66). The incidence of cancer in patients with SLE in the LUNA cohort did not significantly differ from that in the general population. These findings suggest that CNI treatment in this cohort did not pose a risk factor for cancer development.

Comprehensive Analysis of Management Strategies for Red Palm Weevil in Date Palm Settings, Emphasizing Sensor-Based Infestation Detection

The red palm weevil (Rhynchophorus ferrugineus) inflicts widespread damage in date palm plantations and urban settings, leading to stand loss and safety concerns, intensified by the economic and ecological burdens of synthetic preventive treatments. A novel approach emphasizes detecting weevil-infested palms through sensors and targeting control efforts at colonized trees. This study analyzes two datasets: field manager-reported results from settings with preventive pest control versus seismic sensor-monitored units. Sensor data translate into damage index values, exploring curative treatments, attack likelihood based on infestation history, and the impact of sensor-based management on infestation incidence decline. Findings reveal lower weevil infestation in urban areas and preventive-treated palm settings. A strong correlation exists between sensor indications and grower decisions in date plantations. Palms previously infested are more prone to damage. Long-term sensor-based management reduces weevil-affected palm numbers significantly. The high infestation in sensor-equipped date palm settings stems from a gap between sensor-identified and preventively treated palms. Controlling weevils based on sensor indications aligns practically with grower curative treatments, preventing significant damage. Weevils target previously infested palms, optimizing pest control through a continuous strategy integrating sensor monitoring with prompt response treatments. This proves highly effective, offering a cost-efficient alternative to preventive treatment reliance.

Advanced design and Engi-economical evaluation of an automatic sugarcane seed cutting machine based RGB color sensor.

There are many problems related to the use of machine learning and machine vision technology on a commercial scale for cutting sugarcane seeds. These obstacles are related to complex systems and the way the farmers operate them, the possibility of damage to the buds during the cleaning process, and the high cost of such technology. In order to address these issues, a set of RGB color sensors was used to develop an automated sugarcane seed cutting machine (ASSCM) capable of identifying the buds that had been manually marked with a unique color and then cutting them mechanically, and the sugarcane seed exit chute was provided with a sugarcane seed monitoring unit. The machine's performance was evaluated by measuring the damage index at sugarcane stalk diameters of 2.03, 2.72, 3.42, and 3.94 cm. where two different types of rotary saw knives had the same diameter of 7.0 in/180 mm the two knives had 30 and 80 teeth, also we used five cutting times of 1000, 1500, 2000, 2500, and 3000 ms. All tests were done at a fixed cutting speed of 12000 rpm. In addition, the machine's performance was evaluated by conducting an economic analysis. The obtained results showed that the most damage index values were less than 0.00 for all cutting times and sugarcane stalk diameters under testing, while the DI values were equal zero (partial damage) for sugarcane stalk diameter of 3.42 cm at cutting times of 2000 ms and 2500 ms, in addition to the DI values being equal zero (extreme damage) for sugarcane stalk diameter of 3.94 cm at cutting times of 1500 ms and 2000 ms. The economic analysis showed that the total cost of sugarcane seeds per hectare is 70.865 USD. In addition, the ASSCM can pay for itself in a short period of time. The payback time is 0.536 years, which means that the ASSCM will save enough money to pay for itself in about 6.43 months. Finally, we suggest using a rotary saw knife with 80 teeth and a cutting time of 2000 ms to cut sugarcane stacks with an average diameter of 2.72 cm. This will result in higher performance and lower operating costs for the ASSCM.

Damage Localization in Plate Structures Based on Baseline-Free Method of Lamb Wave Using Mobile Transducer Set

Ultrasonic Lamb waves have gained popularity in non-destructive testing of plate-like structures due to their advantages such as low attenuation, high sensitivity, and wide detection range. This paper presents a novel baseline-free method for inspecting curved plate-like structures based on reciprocity loss. The method combines a modified damage imaging algorithm, a baseline-free detection method based on time reciprocity, and a calculation method for damage index values using the analysis of the focus position of time reciprocity signals. Experimental results demonstrate favorable effectiveness of the baseline-free method in detecting and locating multiple defects in the curved plate made of composite laminate.

Efficacy of rituximab on disease activity, severity, and disease-related damage in patients with immunosuppressive-resistant systemic sclerosis.

B-cell depletion with rituximab (RTX) is widely used as a rescue therapy in patients with systemic sclerosis (SSc). The aim herein was to analyze the progress of disease-related outcomes after RTX therapy in severe SSc patients. Included in this study were 27 SSc patients who were followed-up between 2012 and 2020 and received at least 1 cycle of RTX for active disease, despite receiving standard immunosuppressives (ISs). In addition to the European Scleroderma Study Group and European Scleroderma Trials and Research Group activity scores, Medsger's severity, and the recently developed Scleroderma Clinical Trials Consortium Damage Index values were evaluated initially and at 1 year after the first infusion. The progress of individual organ damage was also assessed at the end of the follow-up period (at least 6 months after the last infusion) using the data extracted from the medical records. Disease activity and severity-improved and disease-related overall damage worsened after the first year of RTX therapy (p < 0.001, p = 0.008, and p = 0.005). Some of the disease-related organ damage had improved at the end of the follow-up period, indicating its reversibility. Overall damage scores ≥11 after the first year of RTX therapy were found to be associated with mortality (p = 0.035). RTX contributed to reducing the activity and severity in SSc patients with severe disease, nonetheless the efficacy related to the damage was limited. High damage scores in the first year were found to be associated with mortality. Spontaneous progress of manifestations requiring a longer period to improve and irregular consecutive RTX courses might lead to difficulties in differentiation between activity and damage.

Reducing false alarms in structural health monitoring systems by exploiting time information via Binomial Distribution Classifier

This paper proposes an approach for anomaly/damage detection via structural health monitoring (SHM) systems based on a Binomial Distribution Classifier (BDC). The approach consists of two monitoring levels, labeled as alert and alarm states, respectively, where a damage index (DI) is computed and tracked over time. The alert state is reached when the DI exceeds a given threshold. At this stage, the BDC algorithm starts counting the number of DI values above the threshold within an observation window and computing the related probability of occurrence by using the binomial probability distribution. If the probability falls below a desired limit, the alarm state is triggered. Conversely, the SHM system returns in the non-alert condition. The proposed approach is discussed and evaluated through case studies involving both simulated and experimental data. In the examples, the DI is computed using the Mahalanobis distance of the monitored modal frequencies. The results demonstrate the capability of the BDC to reduce false alarms while preserving the probability of detection.

Damage detection and localization based on different types of actuators using the electromechanical impedance method in 3D-printed material

Electromechanical impedance (EMI) measurement, using piezoelectric transducers (PZTs) in the high-frequency range is a potential method for assessing the health of lightweight structures. The major objective of this work is to comprehend how different actuators react to damage in additively manufactured (AM) polymer structures. A novel frequency-range selection technique was suggested based on the maxima of the standard deviation of the impedance frequency spectra gathered for the referential and damage cases. A 3D-printed acrylonitrile butadiene styrene (ABS) plate was used for the investigation, where two PZT and one macro fiber composite (MFC) actuator were glued to the surface. Small magnets were used to simulate damage and were positioned at increasing distances from each transducer as EMI measurements were made using the MFC and 1 PZT. This served both in studying the transducers’ sensitivity to damage and selecting the proper frequency range for damage detection utilizing the standard-deviation approach. The EMI-acquired data from the MFC actuator displays damage-sensitive peaks in a low-frequency band (0–58 ), while the PZT shows a good sensitivity in a higher frequency range (94–304 ). In order to evaluate the PZT and MFC actuators’ sensitivity to damage in the 3D-printed ABS plate, impact damage is also generated in the plate’s center. The impedance-based damage indices obtained from different types of PZTs (2 PZTs and 1 MFC) were projected to the same base level and then fused—for the first time—for impact-damage localization and further added magnetic mass damage localization. The obtained damage index values of impedance are encouraging for the evaluation of AM polymer structures with a 4.48 mm positional error from a real location by fusing data in the different frequency ranges for PZTs and MFC. The damage localization error increases significantly to the new location beyond the damage sensitivity range of the PZT2 and MFC for the added magnetic mass on the 3D printed structure.