Repair Scheme Research Articles

Repair Scheme of FRP Column Jacketing System for Seismically-vulnerable RC Buildings under Successive Earthquakes

Repair Scheme of FRP Column Jacketing System for Seismically-vulnerable RC Buildings under Successive Earthquakes

Effects of moisture content on strength and compression properties of foundation soils of cultural relics in areas flooded by the Yellow River

This study investigated the effects of soil moisture content on the strength and deformation properties of the foundation soils of cultural relics. Our goal is to inform the formulation and implementation of the repair scheme for cultural relics above the foundation soils and help protect cultural relics. Soil samples with five different moisture contents were prepared and used in unconfined compression, triaxial, and consolidation tests. Several mechanical parameters were determined under different soil moisture contents: failure morphology, compressive strength, compressive modulus, and compressibility coefficient. Based on the test results, the soil cohesion and angle of internal friction were obtained using Mohr’s circle. Regions where the mechanical parameters were particularly sensitive to moisture content were located during the consolidation test. These were also the regions where the soil’s compressive modulus declined rapidly, which was detrimental to the overall stability and safety of overlying structures. The internal structure and particle size distribution of the foundation soils supporting cultural relics were determined by scanning electron microscopy. Constitutive parameters of soils were determined by the triaxial test and consolidation test. It was also found that when the soil moisture content exceeded the optimal level, the foundation soils were very likely to pose a risk to the safety of the overlying cultural relics. The moisture content of foundation soils supporting cultural relics deserves special attention in engineering practice.

A Reliable Low-Latency Multipath Routing Algorithm for Urban Rail Transit Ad Hoc Networks

With the advancement of urban rail transit towards intelligence, the demand for urban rail transit communication has increased significantly, but the traditional urban rail transit vehicle–ground communication system has been unable to meet the future vehicle–ground communication requirements. To improve the performance of vehicle–ground communication, the paper proposes a reliable low-latency multipath routing (RLLMR) algorithm for urban rail transit ad hoc networks. First, RLLMR combines the characteristics of urban rail transit ad hoc networks and uses node location information to configure a proactive multipath to reduce route discovery delay. Second, the number of transmission paths is adaptively adjusted according to the quality of service (QoS) requirements for vehicle–ground communication, and then the optimal path is selected based on the link cost function to improve transmission quality. Third, in order to enhance the reliability of communication, a routing maintenance scheme has been added, and the static node-based local repair scheme is used in routing maintenance to reduce the maintenance cost and time. The simulation results show that compared with traditional AODV and AOMDV protocols, the proposed RLLMR algorithm has good performance in improving latency and is slightly inferior to the AOMDV protocol in improving reliability. However, overall, the throughput of the RLLMR algorithm is better than that of the AOMDV.

Predicting Rutting Development of Pavement with Flexible Overlay Using Artificial Neural Network

Pavement maintenance and repair is a crucial part of pavement management systems. Accurate and reliable pavement performance prediction is the prerequisite for making reasonable maintenance decisions and selecting suitable repair schemes. Rutting deformation, as one of the most common forms of asphalt pavement failures, is a key index for evaluating the pavement performance. To ensure the accuracy of the commonly used prediction models, the input parameters of the models need to be understood, and the coefficients of the models should be locally calibrated. This paper investigates the prediction of the rutting development of pavements with flexible overlays based on the data of the Canadian Long-Term Pavement Performance (C-LTPP) program. Pavement performance data that may be related to rutting were extracted from the survey of Dipstick for data analysis. Then, an artificial neural network (ANN) was adopted to analyze the factors affecting the rut depth, and to establish a model for the rutting development of pavements with flexible overlays. The results of the sensitivity analysis indicate that rutting is not only affected by traffic and climatic conditions, but it is also greatly affected by the thickness of the surface layer and voids in the mixture. Finally, a rutting evaluation index was provided to describe the rutting severity, and the threshold of the pavement maintenance time was proposed based on the prediction results. These results provide a basis for predicting rut development and pavement maintenance.

37‐1: Invited Paper: Manufacturing Readiness of High‐Efficiency and Low‐Cost MicroLED Displays

Applied Materials is pursuing an innovative and manufacturing scalable approach to fabricate full‐color microLED displays on active‐matrix TFT backplanes with four subpixels, high‐efficiency UV‐A microLEDs and in‐situ curing of Cd‐free R/G/B QD formulations. A simplified die‐transfer and much reduced die repair scheme using the 4th subpixel are developed and demonstrated. The readiness of manufacturing tools, materials and processes, and the development of microLEDs with size down to 6µm will be discussed along with progress in assembling smartwatch size displays of superior performance.

Coordinated restoration method of transmission and distribution network considering distribution network fault repair scenario

With the development of active distribution network (ADN) technology, coordinated restoration of transmission network (TN) and ADNs has received widespread attention. As an important part of power system resilience, power system restoration should consider the influence of low-probability high-risk events. Such extreme events are often accompanied by component damage, so the coordination of restoration process and repair scheduling needs to be considered. First, the handling of fault repair scenario on TN and ADNs side during black-start restoration (BSR) is discussed. The interaction between the coordinated restoration of TN/ADNs and the fault repair schemes of ADNs is analyzed. Next, the coordinated restoration of TN/ADNs considering the ADN fault repair scenario is modelled in this paper. For the restoration model of TN, the restoration logic relationship of plants/lines, the subsystem division, frequency constraints of the restored system and the power scheduling constraints of source/load are considered. For the restoration model of ADNs, the restoration logic relationship of DGs/lines/buses, the scheduling logic of repair crews and emergency power sources, frequency constraints and the power scheduling constraints of source/load are considered. Then, an analytical target cascading algorithm is used to solve the optimization model. Finally, a TN/ADNs system is constructed by an IEEE_30 bus transmission system and two IEEE_33 bus distribution system, the numerical case study on the TN/ADNs system verifies that the distributed collaborative optimization of the TN/ADNs restoration plan and the fault repair plan of ADNs can improve the overall restoration efficiency during BSR.

Novel Reinforcing Techniques and Bearing Capacity Analysis for Tunnel Lining Structures with Extensive Corrosion

Affected by the erosive environment, tunnel lining concrete in the long-term service zprocess often exhibits engineering diseases such as concrete corrosion degradation and loss of strength, decreasing the stability of the tunnel lining structure and the traffic safety. Based on HTG tunnel project, the basic distribution rule of tunnel lining corrosion and macro mechanical properties of corroded concrete were explored in this paper through engineering disease site investigation. Then, on this basis, aiming at large-scale corrosion of tunnel lining structure, two reinforcement and repair schemes are proposed, corrugated steel plate reinforcement method and channel steel reinforcement method. Indoor component tests are carried out on the two reinforcement schemes. The failure characteristics and stress and deformation law of tunnel lining members after reinforcement and repair were verified. The analysis showed that the failure process of the reinforced specimens on the tensile side could be divided into the non-cracking stage and the working stage with cracks, and the cracking load and failure load of the specimens were significantly increased. The bearing capacity of the reinforced specimens was divided into the ultimate bearing capacity against cracking and the ultimate bearing capacity during failure. Finally, the calculation methods of the bearing capacity of the channel steel reinforcement method and the corrugated steel plate reinforcement method were derived. Comparative analysis shows that the results of numerical simulation, experimental testing and theoretical simplification methods are close to each other, and the maximum deviation is less than 8%. The established method for calculating the bearing capacity of corroded components after reinforcement is reliable and can be used for the design calculation of corroded lining reinforcement.

Optimal Busy-Node Repair of (k+4,k,4) MDS Codes With Small Sub-Packetization Level

Maximum distance separable array codes with small sub-packetization level (MDS-SSL) are of practical importance in distributed storage systems. This letter addresses their repair of a single failed node in the case that there exists a busy node during the repair. Additional check relations among codeword symbols excluding those in the busy node are formed to compensate for the absence of information. Then, it allows us to repair the failed node without symbols in the busy node. A lower bound of the busy-node repair bandwidth is derived for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(k+4,k,4)$ </tex-math></inline-formula> MDS-SSL codes, consisting of four groups of nodes. It indicates that its achievability requires a cubic constraint among elements in the parity-check matrix. Then, an explicit busy-node repair scheme is proposed to achieve a lower bound in the case of the failed node and the busy node being in different groups.

Clinical study of modified photodynamic therapy combined with Taohong Siwu Decoction in treating hypertrophic scar after severe burn

ObjectiveThe aim of this study was to study the curative effect and the relative mechanism of modified photodynamic therapy combined with Taohong Siwu Decoction in the treatment of hyperplastic scar after severe burn, in order to provide a stable, safe and satisfactory scheme for scar repair. MethodsForty cases with hyperplastic scars after severe burns admitted to the plastic surgery department from May 2021 to May 2022 were divided into a control group and an observation group by means of the random number table method. The control group was treated with ordinary laser therapy combined with Taohong Siwu Decoction, while the observation group was treated with modified photodynamic therapy combined with Taohong Siwu Decoction. The Vancouver Scar Scale (VSS) was assessed in both groups, and the clinical effectiveness of both groups was compared. HE-staining was performed on the scar tissue of the same patient before and after treatment to observe the changes in the arrangement of fibroblasts. The Vascular Endothelial Growth Factor (VEGF), β-Transforming Growth Factor (TGF-β), and Platelet-Derived Growth Factor (PDGF) in the tissue samples of both groups were detected by quantitative real-time PCR. The patients were followed up for 6 months, and their satisfaction, side effects, and scar recurrence were observed. ResultsCompared with the control group, the VSS score in the observation group was lower (p < 0.05). The therapeutic effect of the observation group was superior to the control group after 3 months (p < 0.05). After 3-months of therapy, the arrangement of fibroblasts in the scar became looser in two groups, and the observation group was more looser. The VEGF, TGF-β and PDGF levels in tissue samples of the observation group were lower than those in the control group after 3 months of treatment (p < 0.05). The satisfaction of the observation group was higher than that of the control group (p < 0.05). The adverse reactions between the two groups showed no difference (p > 0.05), while the recurrence rate was lower in the observation group (p < 0.05). ConclusionModified photodynamic therapy combined with Taohong Siwu Decoction shows remarkable efficacy in patients with hyperplastic scars after severe burns. It can improve the color, thickness, vascular distribution, and softness of the scar, and reduce the level of cytokines related to tissue repair. At the same time, it can improve patients' satisfaction with the aesthetic appearance and reduce the recurrence rate, providing a new comprehensive therapy that is safer and more effective, simple and quick, and easy to promote in the clinic.

Research on foreign object damage and grinding repair schemes of compressor blades

Foreign object damage (FOD) on compressor blades of aero-engines lowers the capacity of blades and poses a serious threat to civil aviation safety, so the repair of blades with FOD deserves more attention. The finite element model of the aero-engine compressor blade was established, and the finite element analysis was carried out on the damaged blades with FOD notches and the blades after grinding and repair. The natural frequencies of different types of blades and the global and local peak stress under rotating conditions were compared. It was confirmed that the stiffness of the repaired blades was acceptable, and the optimal grinding repair scheme was selected.

Imperfect maintenance policies for warranted products under stochastic performance degradation

Both customers and manufacturers benefit from warranties that effectively guarantee products’ performance with reasonable price and cost. Reliability-oriented degradation analysis has boosted the accuracy of lifetime prediction in the past decades and prompted additional maintenance and warranty options to manufacturers. In this paper, we present a systematic framework that aims to optimize imperfect maintenance policies for warranted products subject to stochastic performance degradation. We propose a novel objective-oriented imperfect repair scheme, and consider two scenarios corresponding to different types of products/systems. In the first one, warranties are claimed by customers in a random manner driven by performance degradation, whereas in the second one, the manufacturer offers periodic inspection services to customers and implements imperfect repairs if necessary. In both scenarios, we derive critical closed-form results to facilitate computation and optimization, from which managerial insights are gleaned. We find that (i) the randomness in customers’ claiming behaviors leads to remarkably more conservative warranty policies in which repairs are suggested to be more substantial; and (ii) the variable objective repair level in the imperfect repair exercise can effectively reduce the total maintenance cost over a finite warranty period. Overall, this work will equip practitioners with quantitative tools to prescribe optimal maintenance policies for warranted degrading products in various practical scenarios.

Application of Composite Tissue Flap Pedicled With Superficial Temporal Artery and its Branches in the Repair of Various Maxillofacial Defects.

To discuss and study the application of composite tissue flaps pedicled with the superficial temporal artery (STA) and its branches in the repair of various defects, analyze the advantages and disadvantages of such composite tissue flaps, and provide a reference for the personalized design of various maxillofacial defect repairs. In recent years, 12 cases of various maxillofacial defects were repaired with composite tissue flaps pedicled with the STA and its branches. The application strategies of this type of tissue flaps were summarized by summarizing experience and reviewing literature. According to the different defect characteristics of patients and the requirements of patients for surgery, different tissue flaps have been designed, and good results have been obtained. Except for 2 patients who developed dark purple skin flap within 48 hours after operation, the remaining patients were followed up for 6 to 24 months without serious complications. The composite tissue flap pedicled with the STA and its branches is a kind of functional tissue flap for facial defect repair. Individualized repair schemes can be designed according to different defect types of patients.

Torsional repair of damaged single-box multi-cell composite box-girder with corrugated steel webs using CFRP. Part II: Theoretical investigation

Due to their low torsional stiffness, Single-Box Multi-Cell Composite Box-Girders with Corrugated Steel Webs (SBMC-CBGCSWs) under eccentric load are more prone to fail when compared to traditional concrete structures, leading to the increased probability of the need of repair during their life span. To avoid secondary failures and provide a theoretical basis for the evaluation of the optimal repair scheme, a rational rotating-angle model is proposed in this paper to predict the torsional response of damaged SBMC-CBGCSWs repaired with FRP. This proposed model primarily incorporates the effect of FRP on the damaged concrete and proposes constitutive models for the FRP-repaired concrete. At the same time, the effective thickness of shear flow zone for concrete slabs is considered, and the three-stage average stress–strain relationships for concrete struts are proposed for this model. Besides, a new shear strain relationship between inner and outside Corrugated Steel Webs (CSWs) is adopted to estimate the torsional behavior of inner CSWs in SBMC-CBGCSW. The comparison of theoretical predictions and experimental results presented in the companion paper in terms of torque-twist curves, key points, and strains in FRP strips, concrete slabs and CSWs indicates that the proposed model can accurately predict the entire nonlinear behavior of the damaged SBMC-CBGCSWs repaired using CFRP. The parametric study carried out by this proposed model shows that the ultimate strength of CFRP-repaired SBMC-CBGCSWs is approximately linear with the damage coefficient of concrete and the CFRP ratio. In addition, it is found that the effective thickness of shear flow zone and the three-stage average stress–strain relationships for concrete struts adopted in this model can produce reliable predictions of cracking and ultimate torques.

Data-driven optimization of repair schemes and inspection intervals for highway bridges

Routine bridge inspections enable timely maintenance plans based on potential risks. These inspections are performed at fixed time intervals, which may be unnecessarily short for bridges in excellent conditions and precariously long for those in poor conditions. Also, deterioration models used in current bridge management approaches fail to include the effect of age, causing inaccurate predictions. This paper develops a hazard-based bridge management approach where inspection frequencies and repair suggestions are optimized based on hazard levels. A two-dimensional Markov model describes the age-dependent bridge deterioration, and a semi-Markov decision process optimizes inspection intervals and repair decisions. The objective is to minimize the expected long-term total annual costs, including expenses associated with maintenance and traffic detours. The modeling process and maintenance management framework was demonstrated on an example bridge superstructure in New York. The results showed lower annual and total costs than the conventional management method. As expected, sensitivity analyses indicated that the pre-specified choices of inspection intervals for low and high hazard levels have a significant effect on the calculated hazard threshold levels. The proposed maintenance management method is adaptable and practical; bridge authorities can identify appropriate repair actions and make inspection decisions based on simple threshold comparisons.

Numerical study of surface fatigue crack growth in steel plates repaired with CFRP

This paper presents a numerical study of the fatigue behaviour of carbon fibre-reinforced polymer (CFRP) repaired steel plates with a surface crack under uniaxial cyclic tension. A simulation programme for surface fatigue crack propagation has been developed by means of Abaqus-Python scripting. Validation of models was first performed analytically and experimentally, through evaluation of the stress intensity factor (SIF) and fatigue life of unrepaired specimens, respectively. The developed programme was then used to simulate the fatigue behaviour of surface cracked specimens repaired with CFRP sheets. Different aspect ratios of surface cracks, numbers of CFRP layers, CFRP sheet widths and types and CFRP repair schemes (i.e. single- and double-sided reinforcement) were considered, to assess their influence on the CFRP repair efficiency. The results showed that applying CFRP sheets could effectively reduce the SIF of the surface cracks, thereby prolonging the fatigue life of the steel plates. Further, the repair performance improved with more and wider CFRP sheets and higher equivalent modulus but remained almost unchanged for different crack aspect ratios, while the single-sided CFRP repair outperformed the double-sided repair in efficiency. The present study is of instructive value for application of CFRP materials to the repair of surface cracked metallic structures.

Nonlinear Repair of Reed-Solomon Codes

The problem of repairing linear codes and, in particular, Reed Solomon (RS) codes has attracted a lot of attention in recent years due to their extreme importance to distributed storage systems. In this problem, a failed code symbol (node) needs to be repaired by downloading as little information as possible from a subset of the remaining nodes. By now, there are examples of RS codes that have efficient repair schemes, and some even attain the cut-set bound. However, these schemes fall short in several aspects; they require a considerable field extension degree. They do not provide any nontrivial repair scheme over prime fields. Lastly, they are all linear repairs, i.e., the computed functions are linear over the base field. Motivated by these and by a question raised by Guruswami and Wootters, 2017, on the power of nonlinear repair schemes, we study the problem of nonlinear repair schemes of RS codes. Our main results are the first nonlinear repair scheme of RS codes with asymptotically optimal repair bandwidth (asymptotically matching the cut-set bound). This is the first example of a nonlinear repair scheme of any code and also the first example that a nonlinear repair scheme can outperform all linear ones. Lastly, we show that the cut-set bound for RS codes is not tight over prime fields by proving a tighter bound, using additive combinatorics ideas.

A Multipath Local Route Repair Scheme for Bidirectional Traffic in an Airborne Network of Multibeam FDD Nodes

A directional airborne network consisting of nodes equipped with multibeam antennas is considered. These nodes use the frequency division duplex mode of communication. This allows formation of multiple routes between a pair of source and destination nodes, where every forward and reverse route completely overlaps. Each of these routes supports the bidirectional traffic. These routes are formed using the bidirectional ad hoc on-demand multipath distance vector (BAOMDV) routing protocol. In this article, we propose a local route repair scheme, called BAOMDV-LR, when these routes break due to node mobility. The proposed route repair scheme preserves the overlapping and link-disjoint (or node-disjoint) characteristics of the routes, while reducing the need for expensive route rediscovery. The proposed scheme significantly improves the overall network performance for bidirectional traffic (in terms of packet delivery ratio, end-to-end delay, and routing overhead) as compared to the BAOMDV and other existing routing schemes, especially at higher node speeds and data rates.

A new method for function-loss based seismic resilience assessment of buildings

Seismic resilience assessment of buildings is an important aspect in developing resilient buildings. To evaluate seismic resilience of general buildings directly and quickly using a comprehensive index, a new framework of seismic resilience assessment for buildings by assembly-based function loss quantification is developed. Considering the fuzziness uncertainty in evaluation, a new method quantifying function loss of buildings is firstly proposed by consequence analysis of components, logic trees connected with fuzzy operators, and logic system of buildings including relevance between stories. Then the repair scheme of buildings is proposed to compute the time-varying function loss of buildings during the whole recovery process. The proposed method is embedded in probabilistic performance-based earthquake engineering (PBEE), in which uncertainty factors during the whole life cycle of buildings can be considered. Case study on a ten-story RC moment-resisting frame building is provided to demonstrate the applicability of the proposed method. Results show that the case building’s resilience index can be easily and reasonably computed by the proposed framework at different earthquake intensity levels. Compared with the existing assembly-based function methods and resilience assessment methods, the proposed method avoids subjectivity during evaluation greatly. The proposed resilience assessment method can help to develop resilient buildings.

Study of the Explosive Bridge Film Using Laser Shaping Technology

Laser shaping technology and its applications have gained widespread attention in different fields. Using laser repair technology prolongs the service life of micro-explosive products and reduces the production cost, as well as enables the recycling of resources. Although most research mainly focuses on aspheric surface shaping and testing technology, only a few studies on repair technology for micro-explosive products using laser shaping have been reported. To promote the better application of laser shaping technology in the production and repair process of micro-explosive components, this work mainly studied the effect of laser shaping on the repair of an explosive bridge film to enhance the ignition performance and prevent damage. Different processes were used to repair the metal film using laser shaping and non-shaping, respectively. Furthermore, we investigated the similarities and differences of a laser-damaged film surface before and after shaping, and the influence of laser energy parameters on the microstructure and ignition properties of the repaired region. Additionally, we obtained a reasonable repair scheme by analyzing the temperature field variation from the simulation. The results show that the damage caused by the non-shaping and shaping lasers can be repaired using the heat flow and vaporization methods, respectively. By controlling the process parameters, the quality of repair can be improved and the production cost of the bridge film can be reduced.

Comparative Analysis of Domestic and International Test Guidelines for Various Concrete Repair Materials

The number of aged bridges among concrete structures is increasing. Therefore, to increase their lifespans, repair and reinforcement schemes ought to be implemented. This study selected various repair materials according to crack-surface treatment, crack-filling, and crack-injection methods. These repair materials were evaluated using various test methods proposed by the Korean Standards and the American Society for Testing and Materials for structure protection, structure restoration, and crack repair; the results were analyzed and compared. Consequently, the structure restoration material exhibited a similar freezing–thawing trend as that of chloride, while also exhibiting similar flexural, compressive, bond, and splitting-tensile strengths. However, chloride yielded performance differences (up to two-fold) depending on the type of material used for comparison. The crack-repair material yielded similar trends only for bond strength but yielded differences (up to 2–4-fold) in tensile, compressive, and flexural strengths depending on the material used for comparison. These results confirmed that crack-repair materials exhibit significant differences in performance depending on the manufacturer compared with structure protection and structure restoration materials. Therefore, it is expected that repair materials appropriate for usability, durability, and structure safety, while also being environmentally friendly, could be used in future bridge repairs based on these test evaluations.