Corroded Bolt Identification Using Mask Region-Based Deep Learning Trained on Synthesized Data.

The performance of a neural network depends on the availability of datasets, and most deep learning techniques lack accuracy and generalization when they are trained using limited datasets. Using synthesized training data is one of the effective ways to overcome the above limitation. Besides, the previous corroded bolt detection method has focused on classifying only two classes, clean and fully rusted bolts, and its performance for detecting partially rusted bolts is still questionable. This study presents a deep learning method to identify corroded bolts in steel structures using a mask region-based convolutional neural network (Mask-RCNN) trained on synthesized data. The Resnet50 integrated with a feature pyramid network is used as the backbone for feature extraction in the Mask-RCNN-based corroded bolt detector. A four-step data synthesis procedure is proposed to autonomously generate the training datasets of corroded bolts with different severities. Afterwards, the proposed detector is trained by the synthesized datasets, and its robustness is demonstrated by detecting corroded bolts in a lab-scale steel structure under varying capturing distances and perspectives. The results show that the proposed method has detected corroded bolts well and identified their corrosion levels with the most desired overall accuracy rate = 96.3% for a 1.0 m capturing distance and 97.5% for a 15° perspective angle.

Capsule-Like Smart Aggregate with Pre-Determined Frequency Range for Impedance-Based Stress Monitoring.

In this article, a new capsule-like smart aggregate (CSA) is developed and verified for impedance-based stress monitoring in a pre-determined frequency range of less than 100 kHz. The pros and cons of the existing smart aggregate models are discussed to define the requirement for the improved CSA model. The conceptual design and the impedance measurement model of the capsule-like smart aggregate (CSA) are demonstrated for concrete damage monitoring. In the model, the interaction between the CSA and the monitored structure is considered as the 2-degrees of freedom (2-DOF) impedance system. The mechanical and impedance responses of the CSA are described for two conditions: during concrete strength development and under compressive loadings. Next, the prototype of the CSA is designed for impedance-based monitoring in concrete structures. The local dynamic properties of the CSA are numerically simulated to pre-determine the sensitive frequency bands of the impedance signals. Numerical and experimental impedance analyses are performed to investigate the sensitivity of the CSA under compressive loadings. The changes in the impedance signals of the CSA induced by the compressive loadings are analyzed to assess the effect of loading directions on the performance of the CSA. Correlations between statistical impedance features and compressive stresses are also made to examine the feasibility of the CSA for stress quantification.

Raspberry Pi Platform Wireless Sensor Node for Low-Frequency Impedance Responses of PZT Interface.

A wireless impedance monitoring system, called SSeL-Pi, is designed to have cheap, mobile, and handy practical features as compared to wired commercial impedance analyzers. A Raspberry Pi platform impedance sensor node is designed to measure signals at a low-frequency range of up to 100 kHz. The low-frequency impedance measurement via the proposed node has been combined with a new PZT interface technique for measuring local responses sensitive to structural damage. The new PZT interface can work as a surface-mounted or embedded sensor, and its local dynamic characteristics are numerically analyzed to pre-determine an effective impedance resonant frequency range of less than 100 kHz. Next, a software scheme was designed to visualize the input/output parameters of the proposed SSeL-Pi system (i.e., Raspberry Pi platform and PZT interface) and automate signal acquisition procedures of the impedance sensor node. The calibration for impedance signals obtained from the proposed system was performed by a series of procedures, from acquiring real and imaginary impedance to adjusting them with respect to a commercial impedance analyzer (HIOKI-3532). The feasibility of the wireless impedance monitoring system was experimentally evaluated for PZT interfaces that were subjected to various compressive loadings. The consistent results analyzed from signals measured by the SSeL-Pi and HIOKI 3532 systems were observed. Additionally, the strong relationships between impedance features (frequency shift and RMSD index) and compressive stresses of the PZT interfaces showed the potential for axial force/stress variation monitoring in real structures using the Raspberry Pi platform impedance sensor node and developed PZT interface.

N-acetylcysteine reduce the stress induced by cold storage of platelets: A potential way to extend shelf life of platelets.

The room temperature storage used for platelets worldwide leads to platelet storage lesion (PSL) and risk of bacterial growth, limiting platelet shelf life and safety in transfusion. Thus, there is a need for an alternative storage method that can serve as effective temperature storage for platelet concentrates (PCs). In the previous investigation, we have shown that N-acetylcysteine (NAC) is a potential candidate for an additive solution to retain platelet characteristics during cold storage for up to 5 days. However, the study partially describes the efficacy and has drawbacks to address. Here, we used the apheresis platelet product with 50 mM NAC and stored up to 10 days under refrigerated condition (4 ± 1 °C). Stored platelet concentrates were analyzed for critical parameters such as platelet activation, annexin V binding, sialic acid, reactive oxygen species (ROS), neuraminidase activity, and in vivo efficacy using Prkdcscid mice. Investigation observations revealed that PCs with NAC showed reduced platelet activation, annexin V binding, ROS production, and sialic acid levels. in vivo recovery of PCs showed similar recovery rates stored PCs irrespective of treatment or storage condition. However, on the tenth day after 24 h, recovery in room temperature stored concentrates was about 32 %, whereas in NAC treated refrigerated concentrates, it stands at 47 %. These observations indicate that NAC addition protects refrigerated concentrates during long-term storage retaining the platelet integrity. The study also suggests that extending PC storage beyond 10 days is practically accomplishable with efficacy similar to room temperature (RT) stored PCs.

Optimal Localization of Smart Aggregate Sensor for Concrete Damage Monitoring in PSC Anchorage Zone.

This study investigates the feasibility of smart aggregate (SA) sensors and their optimal locations for impedance-based damage monitoring in prestressed concrete (PSC) anchorage zones. Firstly, numerical stress analyses are performed on the PSC anchorage zone to determine the location of potential damage that is induced by prestressing forces. Secondly, a simplified impedance model is briefly described for the SA sensor in the anchorage. Thirdly, numerical impedance analyses are performed to explore the sensitivities of a few SA sensors in the anchorage zone under the variation of prestressing forces and under the occurrence of artificial damage events. Finally, a real-scale PSC anchorage zone is experimentally examined to evaluate the optimal localization of the SA sensor for concrete damage detection. Impedance responses measured under a series of prestressing forces are statistically quantified to estimate the performance of damage monitoring via the SA sensor in the PSC anchorage.

Piezoelectric Sensor-Embedded Smart Rock for Damage Monitoring in a Prestressed Anchorage Zone.

In this paper, a piezoelectric sensor-embedded smart rock is proposed for the electromechanical impedance monitoring of internal concrete damage in a prestressed anchorage zone. Firstly, a piezoelectric sensor-embedded smart rock is analyzed for impedance monitoring in concrete structures. An impedance measurement model is analyzed for the PZT (lead zirconate titanate)-embedded smart rock under compression in a concrete member. Secondly, a prototype of the smart rock embedded with a PZT sensor is designed in order to ascertain, sensitively, the variations of the impedance signatures induced by concrete damage in an anchorage zone. Thirdly, the performance of the smart rock is estimated from a numerical analysis and experimental tests. Variations in the impedance signals under compressive test cases are analyzed in order to predetermine the sensitive frequency band for the impedance monitoring. Lastly, an experiment on an anchorage zone embedded with the smart rocks and surface-mounted PZT sensors is conducted for the impedance measurement under a series of loading cases. The impedance variations are quantified in order to comparatively evaluate the feasibility of the sensor-embedded smart rock for the detection of internal concrete damage in the anchorage zone. The results show that the internal concrete damage was successfully detected using the PZT-embedded smart rock, thus enabling the application of the technique for anchorage zone health monitoring.

Smart PZT-Embedded Sensors for Impedance Monitoring in Prestressed Concrete Anchorage.

This study investigates the feasibility evaluation of smart PZT-embedded sensors for impedance-based damage monitoring in prestressed concrete (PSC) anchorages. Firstly, the concept of impedance-based damage monitoring for the concrete anchorage is concisely introduced. Secondly, a prototype design of PZT-embedded rebar and aggregate (so-called smart rebar-aggregate) is chosen to sensitively acquire impedance responses-induced local structural damage in anchorage members. Thirdly, an axially loaded concrete cylinder embedded with the smart rebar-aggregate is numerically and experimentally analyzed to investigate their performances of impedance monitoring. Additionally, empirical equations are formulated to represent the relationships between measured impedance signatures and applied compressive stresses. Lastly, an experimental test on a full-scale concrete anchorage embedded with smart rebar-aggregates at various locations is performed to evaluate the feasibility of the proposed method. For a sequence of loading cases, the variation in impedance responses is quantified to evaluate the accuracy of smart rebar-aggregate sensors. The empirical equations formulated based on the axially loaded concrete cylinder are implemented to predict compressive stresses at sensor locations in the PSC anchorage.

Correction: Pham et al. Bolt-Loosening Monitoring Framework Using an Image-Based Deep Learning and Graphical Model. Sensors 2020, 20, 3382.

The authors wish to make the following correction to this paper [...].

Monitoring of Corroded and Loosened Bolts in Steel Structures via Deep Learning and Hough Transforms.

In this study, a regional convolutional neural network (RCNN)-based deep learning and Hough line transform (HLT) algorithm are applied to monitor corroded and loosened bolts in steel structures. The monitoring goals are to detect rusted bolts distinguished from non-corroded ones and also to estimate bolt-loosening angles of the identified bolts. The following approaches are performed to achieve the goals. Firstly, a RCNN-based autonomous bolt detection scheme is designed to identify corroded and clean bolts in a captured image. Secondly, a HLT-based image processing algorithm is designed to estimate rotational angles (i.e., bolt-loosening) of cropped bolts. Finally, the accuracy of the proposed framework is experimentally evaluated under various capture distances, perspective distortions, and light intensities. The lab-scale monitoring results indicate that the suggested method accurately acquires rusted bolts for images captured under perspective distortion angles less than 15° and light intensities larger than 63 lux.

Sensor Fault Diagnosis for Impedance Monitoring Using a Piezoelectric-Based Smart Interface Technique.

For a structural health monitoring (SHM) system, the operational functionality of sensors is critical for successful implementation of a damage identification process. This study presents experimental and analytical investigations on sensor fault diagnosis for impedance-based SHM using the piezoelectric interface technique. Firstly, the piezoelectric interface-based impedance monitoring is experimentally conducted on a steel bolted connection to investigate the effect of structural damage and sensor defect on electromechanical (EM) impedance responses. Based on the experimental analysis, sensor diagnostic approaches using EM impedance features are designed to distinguish the sensor defect from the structural damage. Next, a novel impedance model of the piezoelectric interface-driven system is proposed for the analytical investigation of sensor fault diagnosis. Various parameters are introduced into the EM impedance formulation to model the effect of shear-lag phenomenon, sensor breakage, sensor debonding, and structural damage. Finally, the proposed impedance model is used to analytically estimate the change in EM impedance responses induced by the structural damage and the sensor defect. The analytical results are found to be consistent with experimental observations, thus evidencing the feasibility of the novel impedance model for sensor diagnosis and structural integrity assessment. The study is expected to provide theoretical and experimental foundations for impedance monitoring practices, using the piezoelectric interface technique, with the existence of sensor faults.

Bolt-Loosening Monitoring Framework Using an Image-Based Deep Learning and Graphical Model.

In this study, we investigate a novel idea of using synthetic images of bolts which are generated from a graphical model to train a deep learning model for loosened bolt detection. Firstly, a framework for bolt-loosening detection using image-based deep learning and computer graphics is proposed. Next, the feasibility of the proposed framework is demonstrated through the bolt-loosening monitoring of a lab-scaled bolted joint model. For practicality, the proposed idea is evaluated on the real-scale bolted connections of a historical truss bridge in Danang, Vietnam. The results show that the deep learning model trained by the synthesized images can achieve accurate bolt recognitions and looseness detections. The proposed methodology could help to reduce the time and cost associated with the collection of high-quality training data and further accelerate the applicability of vision-based deep learning models trained on synthetic data in practice.

Reconstruction of a large full-thickness abdominal wall defect with flow-through-based alt flaps: A case report.

An extensive 35 × 20 cm sized full-thickness abdominal wall defect was created after resection of aggressive abdominal fibromatosis in a 19-year-old male patient. Immediate reconstruction was not possible due to prolonged operation time and resulting severe bowel edema. A silicone sheet with NPWT was applied over the exposed viscera. After 1 week, silicone sheet was substituted with a composite mesh. Then, abdominal wall reconstruction with bilateral free anterolateral thigh (ALT) flaps (30 × 12 cm and 25 × 12 cm sized) was performed. Since there was only a single reliable recipient vessel available, we linked 2 ALT free flaps sequentially in a flow-through fashion to the left inferior epigastric artery and vein. Two donor sites were closed primarily. The flap fully survived and the defect was covered successfully without any complication for 11 months of follow up. Multiple flaps may be needed for large full-thickness abdominal wall defect coverage. Linked fasciocutaneous free flaps could be a solution with a less donor site morbidity even in the case of limited available recipient vessels. The purpose of this study is to introduce our experience of extensive full-thickness abdominal wall reconstruction using only ipsilateral deep inferior epigastric vessels.

Local Strand-Breakage Detection in Multi-Strand Anchorage System Using an Impedance-Based Stress Monitoring Method-Feasibility Study.

This study investigates the feasibility of impedance-based stress monitoring method for local-strand breakage detection in multi-strand anchorage systems. Firstly, stress fields of a multi-strand anchorage system are numerically analyzed to examine anchorage's responses sensitive to local strand breakage. Secondly, an impedance-based stress monitoring technique via the PZT interface is outlined. Thirdly, a novel hoop-type PZT interface is designed for the multi-strands anchorage to monitor the stress variation induced by the strand breakage. Local dynamic responses of the hoop-type PZT interface are analyzed to predetermine the effective frequency ranges. Finally, the numerical feasibility of the proposed method is verified on a seven-strand anchorage system under various strand breakage cases. Variations in impedance responses are statistically quantified, and broken strands are localized by linear tomography analysis of damage indices. A lab-scale experiment is also conducted on a multi-strands anchorage to evaluate the realistic performance of the hoop PZT interface for impedance-based stress monitoring method.

Sensing Region Characteristics of Smart Piezoelectric Interface for Damage Monitoring in Plate-Like Structures.

For impedance-based damage detection practices, the sensing range of piezoelectric devices is an important parameter that should be determined before real implementations. This study presents numerical and experimental analyses for characterizing the sensing region of a smart PZT (lead⁻zirconate⁻titanate) interface for damage monitoring in plate-like structures. First, a finite element (FE) model of the PZT interface mounted on a plate structure is established. The impedance responses of the PZT interface are numerically simulated under different damage locations inflicted in the plate domain. The impedance features are extracted from the impedance signatures to analyze the sensing distance and the damage detectability of the PZT interface. Next, the splice plate of a bolted connection is selected as a practical plate-like structure for the experimental examination of the PZT interface's sensing region on a limited plate domain. The damage sensitivity behavior of the PZT interface is analyzed with respect to the damage location on the splice plate. An FE analysis of the corresponding PZT interface-splice plate system is also conducted to support the experimental results.

Improvement of ischemic or congested wound conditions by reconstruction with microsurgical flaps.

BACKGROUND: Intractable chronic wounds share the basic problem of the environment being unfavorable for wound healing and prone to infection, inflammation, and recurrences. Microsurgical flap provides a healthy, well-vascularized normal tissue to compromised intractable environment, and promotes wound healing. In this report, we present the results of microsurgical flaps used for the reconstruction of chronic intractable conditions including chronic ulcer with an ischemic environment and pathologic lesions with a congestive environment. PATIENTS AND METHODS: From 1997 to 2015, 18 patients received microsurgical flaps for chronic intractable conditions. Among them, three patients had radiation ulcers with an ischemic environment and 15 had pathologic lesions with a congested environment, such as vascular malformations. Nine patients were male, and nine were female. The mean age was 31.9 years. All patients were treated using radical excision and reconstruction with microsurgical tissue transfer. RESULTS: All flaps survived completely. Among three patients with radiation ulcers, two had minor wound disruptions, which were managed conservatively. No further episodes of infections or breakdowns occurred. Among 15 patients who had pathologic lesions, one suffered facial palsy of the forehead. No complications in terms of infection, or recurrences were noted, and resolution of the residual surrounding lesions was observed on follow-ups. No donor related problems occurred in any patients. The mean follow-up period was 10.7 years. CONCLUSION: In this report, we present the results of reconstruction of chronic intractable conditions using microsurgical flaps. The reconstruction using microsurgical flaps was clinically successful, with long-term improvement of surrounding tissues and no recurrence.

A thoracodorsal artery perforator chimeric free flap for prevention of microvascular pedicle compression in lower extremity reconstruction.

BACKGROUND: Chimeric flaps are often used in reconstructive fields for multiple defects, different functional defects, and extensive defects. In this article, we present the results of the use of thoracodorsal artery perforator (TDAp) chimeric flaps including a latissimus dorsi (LD) or serratus anterior (SA) muscle to prevent pedicle compression for lower extremity reconstruction. METHODS: Nineteen TDAp chimeric flaps were used to prevent pedicle compression. Seven were female and 12 male. Patients' age ranged from 32 to 73 years. After harvesting TDAp skin flap, LD or SA muscle could be harvested along with the thoracodorsal vessels. Skin flap was incorporated into the main defect and muscle cuffs were positioned along the vascular pedicle. RESULTS: In 11 cases, there were two components, a skin flap and a muscle flap, and the other 8 were three components, a skin flap and two muscle flaps. The dimensions of the skin flaps ranged from 8 × 5 to 18 × 10 cm, and the muscle flaps ranged from 3 × 2 cm to 8 × 6 cm. The recipient vessel was anterior tibial artery or dorsalis pedis artery. All flap survived. Five cases suffered minor complications including donor site wound disruption, skin flap wound disruption, partial loss of the skin flap, and partial loss of the SA muscle flap. The mean follow-up was 13.9 months. All the patients were able to wear shoes without debulking procedures. CONCLUSION: The TDAp chimeric flaps including LD or SA muscle flaps were useful for covering the vascular pedicle and relieved vascular compression during lower extremity reconstruction. © 2015 Wiley Periodicals, Inc. Microsurgery, 38:46-50, 2018..

A simple and fast dressing for skin grafts: comparison with traditional techniques.

OBJECTIVE: The split-thickness skin graft (STSG) is commonly used for reconstruction of skin and soft tissue defects. For a successful graft, the thin skin must be in close contact with the recipient bed until the graft stabilises. This study introduces a simple and fast dressing technique, and compares it with the traditional tie-over dressing. METHOD: All patients who received STSGs between January 2013 and March 2015 were identified. From these patients, those who were treated with skin graft only were included in the study. For comparison of the dressing techniques, operation times from skin incision to the end of procedure were analysed, together with the outcomes of the grafts. For the simple and fast method, the dressing was fixed with a skin stapler, and for tie-over dressings, the graft was fixed with sutures. RESULTS: A total of 67 patients (38 females, 29 males), mean age 58.4 years (range: 24-86 years) were included in the study. Average operation times were 22.9 minutes (range: 10-40 minutes) using the simple and fast dressings and 45.3 minutes (range: 20-120 minutes) using the tie-over dressings, demonstrating a significant difference in operation times. Partial graft loss was reported in three cases with the tie-over dressings and in four cases with the simple and fast dressings, without significant difference. CONCLUSION: The simple and fast dressing is easy to apply, is able to be shaped according to the wound surface, and provides a secure dressing over the skin graft.

Managing necrotising fasciitis to reduce mortality and increase limb salvage.

OBJECTIVE: Necrotising fasciitis is a rare soft-tissue infection with a high mortality rate. In this paper we describe our management protocol for necrotising fasciitis, focused on surgical approaches, which increased patients' survival rate. METHOD: Between March 2009 and December 2014, patients suspected of having necrotising fasciitis (based on laboratory and MRI examinations), underwent management for the infection. A patient suspected of having necrotising fasciitis had surgical exploration performed within eight hours. Patients underwent serial debridement every 24-72 hours until infection had been fully eradicated, after which reconstructive surgery was considered. RESULTS: A total of 34 patients underwent management for necrotising fasciitis, 31 of which had the infection confirmed. From this group, the 18 patients who underwent free flap reconstructive surgery were included in the study, nine of which were female with a mean age of 54.3 (range: 28-77) years. The patients underwent 2-5 repeat debridements (mean: 3.5). Reconstructive procedures were latissimus dorsi (LD) myocutaneous flap in 11 patients, and latissimus dorsi chimeric flap in six patients; the remaining patient received an latissimus dorsi myocutaneous flap, an latissimus dorsi perforator flap and an anterolateral thigh flap simultaneously. Patients were discharged from hospital and returned to daily life three weeks after the final procedure. The mean length of follow-up was 34.8 months (range: 12-60 months). All 18 patients survived. CONCLUSION: With multidisciplinary management, the challenge of necrotising fasciitis can be overcome without risk of mortality risk.

Tension Force Estimation in Axially Loaded Members using Wearable Piezoelectric Interface Technique.

Force changes in axially loaded members can be monitored by quantifying variations in impedance signatures. However, statistical damage metrics, which are not physically related to the axial load, often lead to difficulties in accurately estimating the amount of axial force changes. Inspired by the wearable technology, this study proposes a novel wearable piezoelectric interface that can be used to monitor and quantitatively estimate the force changes in axial members. Firstly, an impedance-based force estimation method was developed for axially loaded members. The estimation was based on the relationship between the axial force level and the peak frequencies of impedance signatures, which were obtained from the wearable piezoelectric interface. The estimation of the load transfer capability from the axial member to the wearable interface was found to be an important factor for the accurate prediction of axial force. Secondly, a prototype of the wearable piezoelectric interface was designed to be easily fitted into existing axial members. Finally, the feasibility of the proposed technique was established by assessing tension force changes in a numerical model of an axially loaded cylindrical member and a lab-scale model of a prestressed cable structure.

Preload Monitoring in Bolted Connection Using Piezoelectric-Based Smart Interface.

In this study, a preload monitoring method using impedance signatures obtained from a piezoelectric-based smart interface is presented for bolted girder connections. Firstly, the background theory of the piezoelectric-based smart interface and its implementation into the health monitoring of bolted connections are outlined. A simplified electro-mechanical (EM) impedance model of a smart interface-embedded bolted connection system is formulated to interpret a mechanistic understanding of the EM impedance signatures under the effect of bolt preload. Secondly, finite element modeling of a bolted connection is carried out to show the numerical feasibility of the presented method, and to predetermine the sensitive frequency band of the impedance signatures. Finally, impedance measurements are conducted on a lab-scaled bolted girder connection, to verify the predetermined sensitive frequency range and to assess the bolt preload changes in the test structure.