Journal articles on the topic 'Inspection/repair strategy'
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1
SHEU, SHEY-HUEI, YAN-CHUN CHEN, and LI-HSIU TENG. "OPTIMAL PERIODIC REPLACEMENT POLICY WITH CHECKING TIME." International Journal of Reliability, Quality and Safety Engineering 12, no. 01 (February 2005): 19–29. http://dx.doi.org/10.1142/s0218539305001689.
Abstract:
This investigation considers a generalized inspection policy for a deteriorating production system with general random minimal repair costs. The inspection times for the inspection strategy are assumed to be non-negligible. Additionally, uncertainty probabilities associated with inspections are introduced. Using a dynamic programming formulation, the optimal inspection time for maximizing profit per unit time for a given overhaul/replacement time is determined. Next, the procedure is extended to determine the optimal periodic overhaul/replacement time, as well as the optimal number of inspections and their schedule.
2
Patel, Nirav J., Nikunj J. Dhimar, Pratik D. Solanki, and Jay A. Patel. "Impact of Inspection Strategy on Repairing Cost of Distribution Transformer." Asian Journal of Electrical Sciences 7, no. 1 (May 5, 2018): 20–22. http://dx.doi.org/10.51983/ajes-2018.7.1.2060.
Abstract:
The Objective of the paper is to do Proper Inspection procedure of failed distribution transformer will reduce the repairing cost. Methods and Statistical analysis includes steps to do external and Internal Inspection with care so that it will not add any pointless expense. This paper highlights the Life cycle of failed distribution transformer and foremost objectives of Inspection which is directly affecting the procedure of repairing and its overall repairing cost. Findings of the paper convey that Inspection of failed distribution transformer is a planned technical extent which will affect directly to repair cost. The project can be applied for Proper Inspection practice will absolutely reduce the repair cost and over all transformer repairing expense of DISCOM.
3
Yang, Yingnan, and Hongming Xie. "Determination of Optimal MR&R Strategy and Inspection Intervals to Support Infrastructure Maintenance Decision Making." Sustainability 13, no. 5 (March 2, 2021): 2664. http://dx.doi.org/10.3390/su13052664.
Abstract:
In the commonly used approach to maintenance scheduling for infrastructure facilities, maintenance decisions are made under the assumptions that inspection frequency is periodical and fixed, and that the true state of a facility is revealed through inspections. This research addresses these limitations by proposing a decision-making approach for determining optimal maintenance, repair, and rehabilitation (MR&R) strategy and inspection intervals for infrastructure facilities that can explicitly take into account non-periodical inspections as well as previously considered periodical inspections. Four transition probabilities are proposed to represent four different MR&R strategies. Then, an optimization program is suggested to minimize MR&R and inspection costs of a bridge element network over a given time period, while keeping the condition states of the element network above a predetermined level. A case study was applied to illustrate the proposed approach. The results show that the proposal approach can support decision making in situations where non-periodical inspections and MR&R actions are incorporated into the model development. If employed properly, this may allow agencies to maintain their infrastructure more effectively, resulting in cost savings and reducing unnecessary waste of resources.
4
Thoft-Christensen, P., and J. D. S⊘rensen. "Optimal strategy for inspection and repair of structural systems." Civil Engineering Systems 4, no. 2 (June 1987): 94–100. http://dx.doi.org/10.1080/02630258708970464.
5
Yamashina, H., and H. Mizuyama. "An inspection and repair strategy in automated assembly systems." Journal of Quality in Maintenance Engineering 4, no. 2 (June 1998): 95–106. http://dx.doi.org/10.1108/13552519810213590.
6
YAMASHINA, Hajime, Hajime MIZUYAMA, Makoto KURIMOTO, and Masahiko SHIBUYA. "An Inspection and Repair Strategy in Automated Assembly Systems." Journal of the Japan Society for Precision Engineering 61, no. 7 (1995): 949–53. http://dx.doi.org/10.2493/jjspe.61.949.
7
Chung, Hsin-Yang, Lance Manuel, and Karl H. Frank. "Reliability-Based Optimal Inspection for Fracture-Critical Steel Bridge Members." Transportation Research Record: Journal of the Transportation Research Board 1845, no. 1 (January 2003): 39–47. http://dx.doi.org/10.3141/1845-05.
Abstract:
To prevent fatigue failure of members in steel bridges, one usually needs to perform frequent periodic bridge inspections and employ detailed inspection methods. This is especially true for fracture-critical members or details. Carrying out these inspections puts a large burden on a transportation agency’s bridge maintenance budget. A systematic reliabilitybased method for inspection scheduling is proposed to yield the most economical inspection strategy for steel bridges that, at the same time, guarantees an acceptable safety level through the planned service life. A methodology is presented for evaluating the fatigue reliability of a specified detail classified according to AASHTO fatigue categories. A Miner’s rule approach is used to evaluate the fatigue reliability. The inspection scheduling problem is modeled as an optimization problem with a welldefined objective function that includes the total expected cost of inspection, repair, and failure formulated on the basis of an event tree framework and appropriate constraints in inspection intervals and minimum (target) structural reliability. An optimal inspection-scheduling plan can thus be obtained for any specified fatigue details (fracture-critical details) in steel bridges. Examples presented demonstrate the advantage of the reliabilitybased optimal inspection scheduling in cost saving and structural reliability control over alternative periodic inspection plans. Two numerical examples for a steel bridge in Texas are presented to demonstrate the proposed reliability-based optimal inspection scheduling.
8
Sá, Gonçalo, João Sá, Jorge De Brito, and Bárbara Amaro. "STATISTICAL SURVEY ON INSPECTION, DIAGNOSIS AND REPAIR OF WALL RENDERINGS." Journal of Civil Engineering and Management 21, no. 5 (May 6, 2015): 623–36. http://dx.doi.org/10.3846/13923730.2014.890666.
Abstract:
This paper describes a statistical survey on the pathology, diagnosis and rehabilitation of wall renderings. The survey was based on an inspection and diagnosis support system that comprises the classification of anomalies in renderings, their most probable causes, diagnosis methods and repair and maintenance techniques. The on-site work that led to this statistics collection involved standard inspections of 55 buildings, located in Lisbon, and a total of 150 wall renderings (100 external and 50 interior). The results of this survey provide indications on the intervention actions at the design, execution and use/maintenance stages in order to decrease the magnitude of or eradicate anomalies in wall renderings. The implementation of a system of this kind could directly improve the quality of constructions.
9
Cesare, M., J. C. Santamarina, C. J. Turkstra, and E. Vanmarcke. "Risk-based bridge management: optimization and inspection scheduling." Canadian Journal of Civil Engineering 21, no. 6 (December 1, 1994): 897–902. http://dx.doi.org/10.1139/l94-095.
Abstract:
Bridge management based on reliability methods permits the selection of the set of repair projects that minimizes the total network risk in a planning horizon. This approach, previously proposed by the authors, uses the Markovian model for the decay of structural components, evaluates the overall reliability of the bridge as a system, and computes risk by taking into consideration the consequences of reduced function. This paper presents important additional aspects of risk-based bridge management. First, genetic algorithms are proposed as an alternative optimization strategy; small and large bridge networks are solved, guiding the solution towards minimum risk. Second, Markovian transition matrices for deterioration and post-inspection Bayesian updating are combined to schedule inspections so that the overall reliability of the bridge network is maximized for a given inspection budget. Results from a simulation study using a real bridge network are presented and compared with current inspection practice. Key words: bridge management, reliability, risk assessment, optimization, inspection scheduling.
10
Alfon, Patuan, Johny Wahyuadi Soedarsono, Dedi Priadi, and Sulistijono. "Application of Hoop Stress Limit State and Predicted Corrosion Rate in Underground Gas Transmission Pipeline Inspection Plan." Applied Mechanics and Materials 328 (June 2013): 942–49. http://dx.doi.org/10.4028/www.scientific.net/amm.328.942.
Abstract:
In the transmission pipeline system, decreasing the integrity of the pipe is generally caused by corrosion. Limit state of hoop stress can be applied to determine whether the pipe material is still safe for utilizing below its yield stress. Defining the corrosion rate allowable will be essential in formulating risk of corrosion in the pipeline system. Using an external corrosion rate model generated by soil, the prediction of corrosion rate in every year service life of material will determine the frequency of inspection by adjusting the threshold category. The predicted corrosion rate in every year is as a function of soil resistivity by a factor of coating breakdown and cathodic protection (CP) remaining life. A modified scheme, so called the Inspection-Maintenance-Repair strategy, is an effective method to increase the effectiveness of inspections. The reduction in risk of corrosion is able to extend the inspection plan for several years.
11
Bhatti, J., N. Bhardwaj, and S. Kumar. "Mathematical modelling to industrial repair and maintenance policy system for its reliability." Mathematical Modeling and Computing 8, no. 3 (2021): 465–73. http://dx.doi.org/10.23939/mmc2021.03.465.
Abstract:
The present paper is an initiative taken by emerging reliability model to a automobile repair industries for its products by dividing repair policy into two categories as (a) regular/normal service and (b) strategy for accidental or additional failure. The concept of inspection process has been introduced for proper verification of failure and also to its repairing strategy with time and cost. The maintenance cost for regular services are fixed but for the case of additional failures the additional cost will be decided upon the level of damage. The stochastic analysis for system been numerically and graphically analyzed by calculating reliability variables like MTSF, availability, inspection and maintenance analysis of the system with the concept of geometric distribution, Markov process and regenerative technique. The results been proved beneficial for fulfilling the objective of calculating profit function that increases with increasing repair and decreasing failure rate.
12
Zeng, Yong, Hongmei Tan, and Dahan Chen. "Probabilistic optimization of fatigue maintenance for welded components in steel bridges based on LEFM and LCCM." Engineering review 38, no. 2 (2018): 166–74. http://dx.doi.org/10.30765/er.38.2.4.
Abstract:
In this paper a probabilistic-based method for fatigue maintenance optimization of steel bridge’s welded joints, combined with linear elastic fracture mechanics (LEFM), the structure reliability, and life cycle cost method(LCCM) is proposed. The probabilistic analysis method can be used with the fatigue maintenance of steel bridges. Weld cracks are classified by its size and maintenance decisions, and are made according to its size classification. Maintenance cost is divided into inspection, repair and failure costs, according to the life cycle cost method. The maintenance optimization strategy is transformed to minimize the expected lifetime total costs with the constraints of the minimum acceptable reliability index to attain the most cost-optimal inspection and repair for the balanced costs between risk and safety. An example concerning the transverse stiffeners of welded components in the main girder of suspension bridge is investigated through the research of some parameters sensitivity. Among all the parameters, the inspection cost is the most remarkable. The optimal time interval of repair will delay based on the increase of the inspection cost. The optimal time interval of repair will advance based on the increase of repair cost. A discount rate can drastically change the value of the total cost, but when the probability of failure is very small, the increase of failure cost has little effect on the optimal time interval of repair. The method presented in this paper can be conducted using the similar maintenance of steel structures.
13
Wang, Wen-Ying, Der-Juinn Horng, and Yan-Chun Chen. "Optimal production and inspection strategy while considering preventive maintenance errors and minimal repair." Journal of Information and Optimization Sciences 27, no. 3 (September 2006): 679–94. http://dx.doi.org/10.1080/02522667.2006.10699718.
14
Bekas, D. G., Zahra Sharif Khodaei, and Ferri M. H. Aliabadi. "Structural Health Monitoring of Scarfed Repaired Composite Panels Using Inject-Printed Patterns." Key Engineering Materials 774 (August 2018): 235–40. http://dx.doi.org/10.4028/www.scientific.net/kem.774.235.
Abstract:
A novel strategy is proposed for monitoring of bonded composite repair patch is developed and tested. A specially designed pattern was inject-printed onto the step-sanded repair surface providing real time information about the bondline structural integrity. The obtained results indicated that the proposed methodology was able to detect damage induced by an impact event. Infrared thermography (IrT) and ultrasound inspection were also employed in order to validate the proposed methodology.
15
Osman, Mohd Haniff, and Sakdirat Kaewunruen. "Value of rescheduling of rail inspection." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, no. 3 (December 30, 2018): 321–30. http://dx.doi.org/10.1177/0954409718820968.
Abstract:
A regular rail inspection schedule has been proposed to minimise any detrimental financial cost incurred due to operations under harsh environments. Missing opportunities to detect a defective rail could ultimately lead to its breaking, which would magnify the repair (as well as maintenance) cost by approximately 30–35% per rail-mile. However, the performance of a pre-planned inspection schedule may be affected by disruptions in one or more element(s) of inspection such as machine/vehicle breakdown or track unavailability, which are usually unpredictable events. As part of the justification for the need to manage a disrupted inspection schedule, this paper proposes a methodology that highlights the value of rescheduling. An extensive literature search was undertaken on the rescheduling framework in order to determine the appropriate policies, strategies and methods for rail inspection. As a result, the value of rescheduling is formulated as the ratio of rescheduling cost to a change in the value of risk from a missed opportunity to repair a defective rail, i.e. late defect detection. This numerical formula demonstrates how the proposed methodology is useful for filtering out a rescheduling strategy that has (negative) value when dealing with a disrupted rail inspection schedule. The discussion portrays several potential aspects to feasibly extend the proposed methodology on a large scale of rail network.
16
Brueckner, Rene. "Concrete repair challenges in the Middle East." MATEC Web of Conferences 289 (2019): 10003. http://dx.doi.org/10.1051/matecconf/201928910003.
Abstract:
The root cause analysis, determination of the extent of concrete defects and identification of an appropriate repair strategy can be straightforward, but it also often provides significant challenges to both contractors and engineers. The challenges can be due to a lack of QA/QC documentation, locally available investigation equipment, repair material and techniques and accepting actually feasible solutions. The paper presents a case study of a bridge in the Middle East where the root cause analysis was found to be straightforward but the determination of the extent of non-visible defects and the implementation of a feasible repair strategy proved to be much more complicated. The root cause analysis of the defects was carried out by visual inspection, representative intrusive investigations and a comprehensive document review. The determination of the extent of the defects using GPR techniques proved to be challenging under the local conditions. Even more difficulties were encountered by implementing the developed repair strategies to address the various defects to ensure that the required 120 years design life in a very aggressive environment can be achieved. Several revisions to the repair strategy were necessary to identify the most appropriate solution and to accelerate the programme.
17
DAGG, R. A., and M. NEWBY. "Optimal overhaul intervals with imperfect inspection and repair." IMA Journal of Management Mathematics 9, no. 4 (October 1, 1998): 381–91. http://dx.doi.org/10.1093/imaman/9.4.381.
18
Soedarsono, Johny, Arie Wijaya, Taufik Aditiyawarman, Agus Kaban, Rini Riastuti, Rizal Tresna Ramdhani, and Ayende Ayende. "Development of risk-based inspection of 28-years-old subsea sales gas pipelines to support the energy demand." Eastern-European Journal of Enterprise Technologies 2, no. 3 (122) (April 30, 2023): 17–27. http://dx.doi.org/10.15587/1729-4061.2023.277256.
Abstract:
In the oil and gas industry, maintaining the integrity of production equipment is critical to ensuring the industry’s sustainability. Failure to maintain the integrity of production equipment can result in financial losses for the business. The management of production equipment nearing the end of its design life faces an increasing cost of Inspection, Maintenance, and Repair (IMR). As a result, a strategy to improve the efficiency of IMR is essential. Recent IMR management practices include predictive Risk-Based Inspection (RBI), which is more efficient than Time-Based Inspection (TBI). The research intends to evaluate the 28-year-old subsea sales gas pipeline using API 581 standard quantitative methodology by utilizing the Inline Inspection (ILI). Specifically, the study focuses on measuring the Probability and Consequence Failure of inspected pipelines. The inspection interval is determined based on the minimum allowable thickness. The risk calculation indicates that 12 pipeline segments are at a medium risk level (3 segments, 1D and 1E, and 2C). The remaining nine segments remain at lower risk (1C). Based on the result, segment nine is accepted as the highest PoF value of 1.04E-4 failures per year due to high depletion values due to the higher CoF value at the leak location. The calculation of the inspection interval indicates that the forthcoming Inspection will be due 20 years post the previous assessment. Another method using the Estimated Repair Factor (ERF) thickness limit approach produces the same results. However, assessment using ASME B31.8S provides different results of 10 years intervals when using the same ILI inspection method. This work can be used as a standard guideline to assess the risk of pipelines over a decade in service
19
Xin, Gongfeng, Zhiqiang Liang, Yerong Hu, Guanxu Long, Yang Zhang, and Peng Liang. "Modeling the Optimal Maintenance Strategy for Bridge Elements Based on Agent Sequential Decision Making." Applied Sciences 14, no. 1 (December 19, 2023): 14. http://dx.doi.org/10.3390/app14010014.
Abstract:
In addressing the issues of low efficiency in bridge maintenance decision making, the inaccurate estimation of maintenance costs, and the lack of specificity in decision making regarding maintenance measures for specific defects, this study utilizes data from regular bridge inspections. It employs a two-parameter Weibull distribution to model the duration variables of the states of bridge elements, thereby enabling the prediction of the duration time of bridge elements in various states. Referring to existing bridge maintenance and repair regulations, the estimation process of maintenance costs is streamlined. Taking into account the specific types and development state of bridge defects, as well as considering the adequacy of maintenance and the restorative effects of maintenance measures, an intelligent agent sequential decision-making model for bridge maintenance decisions is established. The model utilizes dynamic programming algorithms to determine the optimal maintenance and repair measures for elements in various states. The decision results are precise, all the way down to the specific bridge elements and maintenance measures for individual defects. In using the case of the regular inspection data of 222 bridges along a highway loop, this study further validates the effectiveness of the proposed research methods. By constructing an intelligent agent sequential decision-making model for bridge element maintenance, the optimal maintenance measures for 21 bridge elements in different states are obtained, thereby significantly enhancing the efficiency of actual bridge maintenance and the practicality of decision results.
20
Yan, Rundong, and Sarah Dunnett. "Improving the Strategy of Maintaining Offshore Wind Turbines through Petri Net Modelling." Applied Sciences 11, no. 2 (January 8, 2021): 574. http://dx.doi.org/10.3390/app11020574.
Abstract:
In order to improve the operation and maintenance (O&M) of offshore wind turbines, a new Petri net (PN)-based offshore wind turbine maintenance model is developed in this paper to simulate the O&M activities in an offshore wind farm. With the aid of the PN model developed, three new potential wind turbine maintenance strategies are studied. They are (1) carrying out periodic maintenance of the wind turbine components at different frequencies according to their specific reliability features; (2) conducting a full inspection of the entire wind turbine system following a major repair; and (3) equipping the wind turbine with a condition monitoring system (CMS) that has powerful fault detection capability. From the research results, it is found that periodic maintenance is essential, but in order to ensure that the turbine is operated economically, this maintenance needs to be carried out at an optimal frequency. Conducting a full inspection of the entire wind turbine system following a major repair enables efficient utilisation of the maintenance resources. If periodic maintenance is performed infrequently, this measure leads to less unexpected shutdowns, lower downtime, and lower maintenance costs. It has been shown that to install the wind turbine with a CMS is helpful to relieve the burden of periodic maintenance. Moreover, the higher the quality of the CMS, the more the downtime and maintenance costs can be reduced. However, the cost of the CMS needs to be considered, as a high cost may make the operation of the offshore wind turbine uneconomical.
21
Yan, Rundong, and Sarah Dunnett. "Improving the Strategy of Maintaining Offshore Wind Turbines through Petri Net Modelling." Applied Sciences 11, no. 2 (January 8, 2021): 574. http://dx.doi.org/10.3390/app11020574.
Abstract:
In order to improve the operation and maintenance (O&M) of offshore wind turbines, a new Petri net (PN)-based offshore wind turbine maintenance model is developed in this paper to simulate the O&M activities in an offshore wind farm. With the aid of the PN model developed, three new potential wind turbine maintenance strategies are studied. They are (1) carrying out periodic maintenance of the wind turbine components at different frequencies according to their specific reliability features; (2) conducting a full inspection of the entire wind turbine system following a major repair; and (3) equipping the wind turbine with a condition monitoring system (CMS) that has powerful fault detection capability. From the research results, it is found that periodic maintenance is essential, but in order to ensure that the turbine is operated economically, this maintenance needs to be carried out at an optimal frequency. Conducting a full inspection of the entire wind turbine system following a major repair enables efficient utilisation of the maintenance resources. If periodic maintenance is performed infrequently, this measure leads to less unexpected shutdowns, lower downtime, and lower maintenance costs. It has been shown that to install the wind turbine with a CMS is helpful to relieve the burden of periodic maintenance. Moreover, the higher the quality of the CMS, the more the downtime and maintenance costs can be reduced. However, the cost of the CMS needs to be considered, as a high cost may make the operation of the offshore wind turbine uneconomical.
22
Hsieh, Nan Kai, Wei Yen Lin, and Hong Tsu Young. "Development of Diagnosis System for Machine Tool Shaft Inspection." Advanced Materials Research 156-157 (October 2010): 1717–24. http://dx.doi.org/10.4028/www.scientific.net/amr.156-157.1717.
Abstract:
Aiming at reducing cost and time of repair, condition-based shaft faults diagnosis is considered an efficient strategy for machine tool community. While the shaft with faults is operating, its vibration signals normally indicate nonlinear and non-stationary characteristics but Fourier-based approaches have shown limitations for handling this kind of signals. The methodology proposed in this research is to extract the features from shaft faults related vibration signals, from which the corresponding fault condition is then effectively identified. With an incorporation of empirical mode decomposition (EMD) method, the model applied in this research embraces some characteristics, like zero-crossing rate and energy, of intrinsic mode functions (IMFs) to represent the feature of the shaft condition.
23
Stewart, Ross, Alvin Ng, Stuart Trezise, Phillip East, and Kevin Jackson. "C-130H Centre Wing Lower Surface Tang Blend Repair Management." Advanced Materials Research 891-892 (March 2014): 1071–76. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1071.
Abstract:
The RAAF found significant corrosion on the C-130H fleet Centre Wing Lower Surface (CWLS) panels at the tangs adjacent to the rainbow fittings. Repair of this corrosion involves blends and spot facing, and often requires the addition of a doubler to reinforce the region. All RAAF C-130H aircraft had various combinations of spot faces, blends and in some cases doublers at this location. Due to the number and combination of repairs, providing fleet wide management advice is problematic. The fleet condition was assessed from damage maps, repairs and previous analyses. From this a number of worst case configurations were determined. A Finite Element Model was developed and used to determine the bearing and by-pass loads in each fastener row of the panel tangs. Stress intensity correction factors were developed for cracks growing from or to a spot face using Stress Check. These correction factors were applied on top of geometry factors for the baseline configuration. A Damage Tolerance Assessment (DTA) was performed to assess the impact of spot face and blend repairs on the centre wing lower surface panel tangs, in order to develop a fleet wide management strategy. Based on the results for the repair cases, it was shown that the repairs identified in the damage maps could be managed within the existing safety by inspection program.
24
Nordin, Mohd Hisham, Sanjay Sharma, Asiya Khan, Mario Gianni, Sulakshan Rajendran, and Robert Sutton. "Collaborative Unmanned Vehicles for Inspection, Maintenance, and Repairs of Offshore Wind Turbines." Drones 6, no. 6 (May 26, 2022): 137. http://dx.doi.org/10.3390/drones6060137.
Abstract:
Operations and maintenance of Offshore Wind Turbines (OWTs) are challenging, with manual operators constantly exposed to hazardous environments. Due to the high task complexity associated with the OWT, the transition to unmanned solutions remains stagnant. Efforts toward unmanned operations have been observed using Unmanned Aerial Vehicles (UAVs) and Unmanned Underwater Vehicles (UUVs) but are limited mostly to visual inspections only. Collaboration strategies between unmanned vehicles have introduced several opportunities that would enable unmanned operations for the OWT maintenance and repair activities. There have been many papers and reviews on collaborative UVs. However, most of the past papers reviewed collaborative UVs for surveillance purposes, search and rescue missions, and agricultural activities. This review aims to present the current capabilities of Unmanned Vehicles (UVs) used in OWT for Inspection, Maintenance, and Repair (IMR) operations. Strategies to implement collaborative UVs for complex tasks and their associated challenges are discussed together with the strategies to solve localization and navigation issues, prolong operation time, and establish effective communication within the OWT IMR operations. This paper also briefly discusses the potential failure modes for collaborative approaches and possible redundancy strategies to manage them. The collaborative strategies discussed herein will be of use to researchers and technology providers in identifying significant gaps that have hindered the implementation of full unmanned systems which have significant impacts towards the net zero strategy.
25
Wang, Hui Ping, and Qiao Jin. "Study of the Baseline Finite Element Model of a Cable-Stayed Bridge Based on the Field Inspection Data." Advanced Materials Research 243-249 (May 2011): 1908–16. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1908.
Abstract:
For steel cable-stayed bridges which have been operating for many years, their static and dynamic parameters have been being changed because of corrosion and overloading. Therefore, an adjustable numerical model, describing and orienting all the various phases of the safety status of bridges, is needed for a theoretical guide of daily maintenance or periodical repair for them. In order to build such a model reflecting the different phases of working conditions of a bridge, a link between the model and the present condition of the targeted bridge should be erected by periodical field inspections for the structure. In this paper, backed on a practical engineering example, the Shengli cable-stayed bridge of Dongying, a finite element model (FEM) based on the periodical field inspection data was proposed, which could possess a strategy modified correspondingly according to parts or all of the results in the field inspections. Specifically, for the initial FEM, three important issues in the modeling of such a complicated bridge, such as simulation of boundary conditions, equivalence of orthotropic steel deck, and implementation of accurate cable tensions, were firstly studied. Then, the initial finite element model built was modified in terms of the optimization principle by minimizing the difference between the static deflections resulting from the field inspection and those calculated by the FEM before being modified. Lastly, dynamic results from the field inspection were compared with those from the optimized FEM to justify feasibility and reasonability of the developed three-dimension FEM which could reflect one or some certain properties of the structure we were emphatically paying attention to. This model-building and model-modifying method for the baseline FEM of the Shengli cable-stayed bridge also provided reference for the similar existing cable-stayed bridges.
26
Cheung, Moe M. S., Kevin K. L. So, and Xue Qing Zhang. "Life Cycle Cost Management Strategy on Corrosion Deterioration and Fatigue Damage of Steel Girder Bridge." Key Engineering Materials 385-387 (July 2008): 845–48. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.845.
Abstract:
This paper proposes a life-cycle cost (LCC) management methodology that integrates corrosion deterioration and fatigue damage mechanisms. This LCC management methodology has four characterized features: (1) corrosion deterioration and fatigue damage models are used to predict the time when the pre-defined limits are reached; (2) the performance of the steel girder is measured by condition state sets in which deflection, moment and shear capacities and fatigue strength limits are considered altogether; (3) the cost-effectiveness of management strategies are measured by the performance improvement per unit of money spent; and (4) the LCC model includes initial design/construction cost, inspection cost, maintenance cost, repair/rehabilitation cost and failure cost. A steel girder bridge is used as an example to demonstrate the application of the proposed LCC management methodology.
27
Amaro, Bárbara, Diogo Saraiva, Jorge de Brito, and Inês Flores-Colen. "STATISTICAL SURVEY OF THE PATHOLOGY, DIAGNOSIS AND REHABILITATION OF ETICS IN WALLS." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 20, no. 4 (March 12, 2014): 511–26. http://dx.doi.org/10.3846/13923730.2013.801923.
Abstract:
This paper presents a statistical survey on the pathology, diagnosis and rehabilitation of ETICS (external thermal insulation composite system) in walls. The development of an expert-knowledge inspection and diagnosis system for this type of cladding implied the creation of classification lists of anomalies, most probable causes, diagnosis methods and repair/maintenance techniques. The collection of data through field work where the tools developed within the proposed system were applied was the basis for this statistical survey. The field work consisted of the visual inspection of 146 façades with ETICS cladding located in various areas in Portugal and aged from 3 to 22 years. The data obtained enable anomalies to be related to their causes and so conclusions can be drawn on the best way to minimize the development of the former and eliminate the latter, at the design and application stages. The study further revealed the main sensitive issues of the cladding system during its service life, highlighting the importance of a correct maintenance plan.
28
Hoshino, Satoshi, Hiroya Seki, Yuji Naka, and Jun Ota. "Fault-Tolerant Multi-Robot Operational Strategy for Material Transport Systems Considering Maintenance Activity." Journal of Robotics and Mechatronics 22, no. 4 (August 20, 2010): 485–95. http://dx.doi.org/10.20965/jrm.2010.p0485.
Abstract:
In automated robotic systems, a robot undergoing corrective maintenance (i.e., repair) or preventive maintenance (i.e., inspection) may become a disturbance of operations for other working robots. Therefore, maintenance of a robot has to be performed adequately. Multi-robot systems have the capability for the substitution and complement of such a robot. To introduce the multi-robot technology in industrial applications, we propose fault-tolerant multi-robot operational strategies for a material transport system focusing on the robot behavior. Working robots, while switching between normal and fault-tolerant operational strategies reactively according to the presence or absence of a robot undergoing maintenance, accomplish tasks. Through simulation experiments, the effectiveness of the proposed strategies is discussed. In addition, an integrated strategy for some failure rates of the robot is investigated. Finally, a maintenance activity for the robots is modeled on the basis of reliability engineering and the reasonability of preventive and corrective maintenance is discussed.
29
Dong, Jun, and Chunming Ye. "Research on Two-Stage Joint Optimization Problem of Green Manufacturing and Maintenance for Semiconductor Wafer." Mathematical Problems in Engineering 2020 (January 24, 2020): 1–22. http://dx.doi.org/10.1155/2020/3974024.
Abstract:
This paper proposes a two-stage joint optimization problem of green manufacturing and maintenance for semiconductor wafer (TSGMM-SW) considering manufacturing stage, inspection, and repair stage simultaneously, which is a typical NP-hard problem with practical research significance and value. Aiming at this problem, a green scheduling model with the objective of minimizing makespan, total carbon emissions, and total preventive maintenance (PM) costs is constructed, and an improved hybrid multiobjective multiverse optimization (IHMMVO) algorithm is proposed in this paper. The joint optimization of green manufacturing and maintenance is realized by designing synchronous scheduling and maintenance strategy for wafer manufacturing and equipment PM. The diversity of the population is expanded and the optimization performance of IHMMVO is improved by designing the initial population fusion strategy and subpopulation evolution strategy. In the experimental phase, we perform the simulation experiments of 900 test cases randomly generated from 90 parameter combinations. The IHMMVO algorithm is compared with other existing algorithms to verify the effectiveness and feasibility for TSGMM-SW.
30
Craeye, Bart, Lydia Wittocx, Neel Renne, Peter Minne, and Robby Caspeele. "Assessment of cantilevered concrete balconies by means of practically oriented evaluation tools." MATEC Web of Conferences 364 (2022): 03003. http://dx.doi.org/10.1051/matecconf/202236403003.
Abstract:
Facing the aging building stock, challenging times can be expected with a sharp increase of reinforced concrete buildings requiring maintenance, repair and/or replacement. For the condition assessment of existing reinforced concrete structures an in-depth and reliable inspection strategy and evaluation is essential to come to a durable and service-life extending repair strategy. A stepwise protocol to evaluate the condition and remaining bearing capacity of cantilevered reinforced concrete (RC) balconies is presented in this paper. Corrosion causing the reduction of the steel section, incorrect positioning of the reinforcement and/or higher loads are the main reasons service life might not be reached or the failure of the balcony can occur. As mentioned in EN 1504-9 and NEN 8700, an adequate diagnosis prior to repair showing the cause and extent of the damage is important (i) to determine the actual bearing capacity, (ii) to make an estimation of the residual lifespan and (iii) to select a durable repair technique and/or define maintenance requirements. In this paper a newly developed protocol for the assessment of the condition and the bearing capacity of the cantilevered RC balconies of a high-rise residential building is demonstrated. A semi-probabilistic method is used by applying partial safety factors based on Eurocode guidelines and fib Bulletin 80. The condition of the structure is determined based on NEN2767 regulations. As corrosion is the main contributor to the degradation of existing concrete structures, a chloride contaminated building with damaged reinforced concrete balconies is selected as case study in order to demonstrate the applicability of the developed protocol and tools.
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Hariga, M., and N. Azaiez. "Heuristic procedures for the single facility inspection problem with minimal repair and increasing failure rate." Journal of the Operational Research Society 57, no. 9 (September 2006): 1081–88. http://dx.doi.org/10.1057/palgrave.jors.2602074.
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Pereira, Ana, Filipe Palha, Jorge de Brito, and José Dinis Silvestre. "DIAGNOSIS AND REPAIR OF GYPSUM PLASTER COATINGS: STATISTICAL CHARACTERIZATION AND LESSONS LEARNED FROM A FIELD SURVEY." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 20, no. 4 (March 10, 2014): 485–96. http://dx.doi.org/10.3846/13923730.2013.801918.
Abstract:
This paper provides the statistical characterization of the pathological situation of 119 gypsum plaster coatings applied to partition walls and ceilings (inner gypsum plasters – IGP), the diagnosis methods that can be used to characterize the defects and confirm their causes, and the most suitable repair solutions. The results presented in this paper were achieved via the use of an expert system developed by the authors in an extensive inspection programme covering 23 buildings. A comprehensive set of charts and their detailed statistical analysis describe the results achieved, including the characteristics (temporal, spatial and severity) and frequency of the defects in the sample and the main causes of their occurrence in walls and ceilings. The most appropriate diagnosis methods, preventive measures and repair solutions prescribed for these defects in the sample are also analyzed and the most significant correlations presented. Even though in some instances the pathological situation of IGP is common knowledge, this time it has been characterized via quantitative indicators and using a statistically significant sample, which means that important lessons can be learned.
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Makuch, Maria, and Pelagia Gawronek. "3D Point Cloud Analysis for Damage Detection on Hyperboloid Cooling Tower Shells." Remote Sensing 12, no. 10 (May 12, 2020): 1542. http://dx.doi.org/10.3390/rs12101542.
Abstract:
The safe operation and maintenance of the appropriate strength of hyperboloid cooling towers require special supervision and a maintenance plan that takes into consideration the condition of the structure. With three series of terrestrial laser scanning data, the paper presents an automatic inspection system for reinforced concrete cooling tower shells that ensures detection and measurement of damage together with the verification of the quality and durability of surface repairs as required by industry standards. The proposed solution provides an automatic sequence of algorithm steps with low computational requirements. The novel method is based on the analysis of values of the local surface curvature determined for each point in the cloud using principal component analysis and transformed using the square root function. Data segmentation into cloud points representing a uniform shell and identified defects was carried out using the region growing algorithm. The extent of extracted defects was defined through vectorisation with a convex hull. The proposed diagnostics strategy of reinforced concrete hyperboloid cooling towers was drafted and validated using an object currently under repair but in continuous service for fifty years. The results of detection and measurement of defects and verification of surface continuity at repaired sites were compared with traditional diagnostics results. It was shown that the sequence of algorithm steps successfully identified all cavities, scaling, and blisters in the shell recorded in the expert report (recognition rate—100%). Cartometric vectorisation of defects determined the scope of necessary shell repairs offering higher performance and detail level than direct contact measurement from suspended platforms. Analysis of local geometric features of repaired surfaces provided a reliable baseline for the evaluation of the repairs aimed at restoring the protective properties of the concrete surround, desirable especially in the warranty period.
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YUM†, BONG JIN, and EDWARD D. McDOWELLJ‡. "Optimal inspection policies in a serial production system including scrap rework and repair: An MILP approach." International Journal of Production Research 25, no. 10 (October 1987): 1451–64. http://dx.doi.org/10.1080/00207548708919925.
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Zhang, Yan, Miao Xu, Xiangzhou Deng, Yan Wei, and Yuyong Han. "Teaching practice research of higher vocational course the inspection and repair of automobile comfort and safety system in moral education." SHS Web of Conferences 140 (2022): 01032. http://dx.doi.org/10.1051/shsconf/202214001032.
Abstract:
This article aims to study how to integrate the educational goal of cultivating talents through moral cultivation with the theoretical and practical teaching of the professional course. In order to realize a new teaching pattern of education, the study combined the professional course teaching with the ideological and political theory course teaching during the research process. Based on the practical teaching cases, this study followed the principle of combining qualitative and quantitative researches. The paper adopted several effective methods such as observation method, literature research method and case analysis method. It sums up the implementation approach of curriculum ideological and political construction strategy of “three integrations, two innovations and one connection”, so as to fulfill the fundamental task of establishing morality and cultivating talents.
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Desnerck, Pieter, Pierfrancesco Valerio, Janet M. Lees, and Neil Loudon. "Suggestions for improved reinforced concrete half-joint bridge inspection in England." MATEC Web of Conferences 199 (2018): 06004. http://dx.doi.org/10.1051/matecconf/201819906004.
Abstract:
Asset management databases play a crucial role in the management of existing infrastructure assets. Highways England (HE) has a long history of using bridge management software to record the current state of bridges and to guide maintenance schemes and interventions. Reinforced concrete half-joints are amongst the most challenging structures to inspect and repair due to their susceptibility to deterioration and construction type. Hence, they require particular attention within asset management programmes. An Interim Management Strategy was developed by HE to identify all the structures on the Highways England road network with half-joint elements. These half-joint structures were then subjected to a special inspection regime. Out of the 428 half-joint structures with inspection data, 252 structures had defects associated with four existing HE defect classes. A review of the inspection database with a focus on half-joints led to an alternative classification of half-joint related defects based on a revised set of Defect Classes, the introduction of Defect Groups and the extraction of Defect Types specifically observed in half-joints. Using this new classification, the most common half-joint Defect Groups were found to be cracking, corrosion, spalling and deterioration mechanisms. In about half of the structures cracking and corrosion tended to be observed together. Correlations were also shown to exist between structural and deterioration, and constructional Defect Classes, emphasising the need for quality control and proper workmanship. Recommendations to address shortcomings in current inspection practice are proposed. Clearer defect definitions and decision-tree guidance for inspectors could enhance the consistency and repeatability of inspection data gathering thereby overcoming some of the limitations of subjective classifications. Acquiring additional information about the observed crack details including zonal information, crack patterns, crack extent, crack orientations and widths combined with local and global pictorial evidence would also be advantageous. This could then provide the basis for the automatic processing and identification of structures with specific half-joint related defects. In this way, asset managers would be better able to allocate limited resources to the most critical structures.
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Murugan, Raji, and Ramasamy Raju. "Evaluation of in-service power transformer health condition for Inspection, Repair, and Replacement (IRR) maintenance planning in electric utilities." International Journal of System Assurance Engineering and Management 12, no. 2 (March 13, 2021): 318–36. http://dx.doi.org/10.1007/s13198-021-01083-1.
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Rasiulis, Konstantin, and Kęstutis Gurkšnys. "ANALYSES OF THE STRESS INTENSITY OF THE CYLINDRICAL TANK WALL AT THE PLACE OF THE GEOMETRICAL DEFECT." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 16, no. 2 (June 30, 2010): 209–15. http://dx.doi.org/10.3846/jcem.2010.23.
Abstract:
Major repair or regular inspection of the large capacity thin‐walled tankages is very expensive. Steel cylindrical tanks are an individual case of the thin‐walled tankages. The common calculation of the tanks by analytical and numerical methods is not difficult. Strengthening the places, where a perfect calculated form is disturbed, that is, at the spots of in‐cuts, hatches, defects etc. is a responsible part of the design of such constructions. The problems of prevention of defects during the operation period and repairs, as well as possibility to assure quickly the safety of defective places of the constructions are more important than the common calculations. The main objective of the presented investigations is to identify stress/strain state of the wall tank with local imperfections from the ideal cylindrical surface, taking into account the membrane theory of the shells by using the finite element's method. Santrauka Didelio tūrio statiniu remontai arba net profilaktines apžiūros yra gana brangūs procesai. Metalines cilindrines talpyklos priskiriamos prie atskiros tūriniu plonasieniu konstrukciju grupes. Talpyklu reguliariu konstrukciju analitiniai ar skaitiniai skaičiavimai nera sudetingi. Bet tokiu vietu, kaip konstrukciju jungčiu bei technologines irangos prijungimo projektavi‐mas ar konstrukciju defektu analize yra gerokai svarbesne projektavimo dalis. Defektu prevencija naudojant talpyklas, taip pat defektuotu vietu sustiprinimas yra svarbesnis nei bendrieji talpyklu skaičiavimai. Šio darbo tikslas ‐ nustatyti realaus objekto cilindrines talpyklos sieneles su geometrinemis lokaliomis nuokrypomis itempiu ir deformaciju būvi pagal memb‐ranine kevalu skaičiavimo teorija, taikant baigtiniu elementu metoda.
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Dinmohammadi, Fateme. "A risk-based modelling approach to maintenance optimization of railway rolling stock." Journal of Quality in Maintenance Engineering 25, no. 2 (May 7, 2019): 272–93. http://dx.doi.org/10.1108/jqme-11-2016-0070.
Abstract:
Purpose Railway transport maintenance plays an important role in delivering safe, reliable and competitive transport services. An appropriate maintenance strategy not only reduces the assets’ lifecycle cost, but also will ensure high standards of safety and comfort for rail passengers and workers. In recent years, the majority of studies have been focused on the application of risk-based tools and techniques to maintenance decision making of railway infrastructure assets (such as tracks, bridges, etc.). The purpose of this paper is to present a risk-based modeling approach for the inspection and maintenance optimization of railway rolling stock components. Design/methodology/approach All the “potential failure modes and root causes” related to rolling stock systems are identified from an extensive literature review followed by an expert’s panel assessment. The failure causes are categorized into six groups of electrical faults, structural damages, functional failures, degradation, human errors and natural (external) hazards. Stochastic models are then proposed to estimate the likelihood (probability) of occurrence of a failure in the rolling stock system. The consequences of failures are also modeled by an “inflated cost function” that involves safety-related costs, corrective maintenance and renewal (M&R) costs, the penalty charges due to train delays or service interruptions as well as the costs associated with loss of reputation (or loss of fares) in the case of trip cancellation. Lastly, a time-varying risk-cost function is formulated to determine the optimal frequency of preventive inspection and maintenance actions for rolling stock components. Findings For the purpose of clearly illustrating the proposed risk-based inspection and maintenance modeling methodology, a case study of the Class 380 train’s pantograph system from a Scottish train operating company is provided. The results indicate that the proposed model has a substantial potential to reduce the M&R costs while ensuring a higher level of safety and service quality compared to the currently used inspection methodologies. Practical implications The railway rolling stocks should be regularly inspected and maintained so as to ensure network availability and reliability, passenger safety and comfort, and operations efficiency. Despite the best efforts of the maintenance staff, it is reported that a considerable amount of maintenance resources (e.g. budget, time, manpower) is wasted due to insufficiency or inefficiency of current periodic M&R interventions. The model presented in this paper helps the maintenance engineers to assess the current maintenance practices and propose or initiate improvement actions when needed. Originality/value There are few studies investigating the application of risk-based tools and techniques to inspection and maintenance decision making of railway rolling stock components. This paper presents a modeling approach aimed at planning the preventive repair and maintenance interventions for rolling stock components based on risk measures. The author’s model is also capable of incorporating real measurement information gathered at each inspection epoch to update future inspection plans.
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Alshannag, M. J., and M. Higazey. "Condition assessment and renovation of an aged precast reinforced concrete multi-storey building." IOP Conference Series: Earth and Environmental Science 1026, no. 1 (May 1, 2022): 012016. http://dx.doi.org/10.1088/1755-1315/1026/1/012016.
Abstract:
Abstract This paper assesses the condition of a 45 years old precast reinforced concrete multistorey building and proposes innovative repair techniques for extending its service life. The residential building investigated consists of six floors, and each floor consists of 4 apartments with a total floor area of 900 m2. Initially, visual inspection was conducted to identify the extent of deterioration in all parts of the building, followed by field non-destructive and destructive tests to determine the root causes of the damage. Moreover, analytical tools such as ETABS and SAFE design softwares were used by applying the same loading assumptions and material properties given by the designer, to check the compliance of the building with the safety requirements specified in ACI 318-14/SBC 304-18 building codes. The field and laboratory checks confirmed the occurrence of considerable degree of deterioration in some elements of the building due to reinforcement corrosion, alkali silica reaction (ASR), salt–scaling and leaching. The analytical checks revealed excessive deflections, due to a design error. Several advanced repair techniques including carbon fiber reinforced polymer sheets (CFRP), and steel jackets were implemented to restore the structural load carrying capacity of the columns and beams that suffered extensive deterioration. The excessive deflections were reduced below the code limit by supporting the deflected slabs using wide flanged I-section steel beams. Moreover, the Repair strategy proposed included, removal of the deteriorated concrete, coating the exposed steel bars with a protective anti-corrosive coating, and cathodic protection of the steel bars followed by injecting high strength cementitious grout.
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Dhawalikar, Mahesh Narayan, V. Mariappan, P. K. Srividhya, and Vishal Kurtikar. "Multi-state failure phenomenon and analysis using semi-Markov model." International Journal of Quality & Reliability Management 35, no. 9 (October 1, 2018): 2080–91. http://dx.doi.org/10.1108/ijqrm-01-2016-0001.
Abstract:
Purpose Degraded failures and sudden critical failures are quite prevalent in industries. Degradation processes commonly belong to Weibull family and critical failures are found to follow exponential distribution. Therefore, it becomes important to carry out reliability and availability analysis of such systems. From the reported literature, it is learnt that models are available for the situations where the degraded failures as well as critical failures follow exponential distribution. The purpose of this paper is to present models suitable for reliability and availability analysis of systems where the degradation process follows Weibull distribution and critical failures follow exponential distribution. Design/methodology/approach The research uses Semi-Markov modeling using the approach of method of stages which is suitable when the failure processes follow Weibull distribution. The paper considers various states of the system and uses state transition diagram to present the transition of the system among good state, degraded state and failed state. Method of stages is used to convert the semi-Markov model to Markov model. The number of stages calculated in Method of stages is usually not an integer value which needs to be round off. Method of stages thus suffers from the rounding off error. A unique approach is proposed to arrive at failure rates to reduce the error in method of stages. Periodic inspection and repairs of systems are commonly followed in industries to take care of system degradation. This paper presents models to carry out reliability and availability analysis of the systems including the case where degraded failures can be arrested by appropriate inspection and repair. Findings The proposed method for estimating the degraded failure rate can be used to reduce the error in method of stages. The models and the methodology are suitable for reliability and availability analysis of systems involving degradation which is very common in systems involving moving parts. These models are very suitable in accurately estimating the system reliability and availability which is very important in industry. The models conveniently cover the cases of degraded systems for which the model proposed by Hokstad and Frovig is not suitable. Research limitations/implications The models developed consider the systems where the repair phenomenon follows exponential and the failure mechanism follows Weibull with shape parameter greater than 1. Practical implications These models can be suitably used to deal with reliability and availability analysis of systems where the degradation process is non-exponential. Thus, the models can be practically used to meet the industrial requirement of accurately estimating the reliability and availability of degradable systems. Originality/value A unique approach is presented in this paper for estimating degraded failure rate in the method of stages which reduces the rounding error. The models presented for reliability and availability analyses can deal with degradable systems where the degradation process follows Weibull distribution, which is not possible with the model presented by Hokstad and Frovig.
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Ahmad, Zaheer, Zek Lim, Kevin Roman, Marcus Haw, Robert H. Anderson, and Joseph Vettukattil. "The angulation of the septal structures impacts ventricular imbalance in atrioventricular septal defects with a common atrioventricular junction." Cardiology in the Young 26, no. 2 (March 3, 2015): 321–26. http://dx.doi.org/10.1017/s1047951115000219.
Abstract:
AbstractObjectiveMultiplanar re-formatting of full-volume three-dimensional echocardiography data sets offers new insights into the morphology of atrioventricular septal defects. We hypothesised that distortion of the alignment between the atrial and ventricular septums results in imbalanced venous return to the ventricles, with consequent proportional ventricular hypoplasia.MethodsA single observer evaluated 31 patients, with a mean age of 52.09 months, standard deviation of 55, and with a range from 2 to 264 months, with atrioventricular septal defects, of whom 17 were boys. Ventricular imbalance, observed in nine patients, was determined by two-dimensional assessment, and confirmed at surgical inspection in selected cases when a univentricular strategy was undertaken. Offline analysis using multiplanar re-formatting was performed. A line was drawn though the length of the ventricular septum and a second line along the plane of the atrial septum, taking the angle between these two lines as the atrioventricular septal angle. We compared the angle between 22 patients with adequately sized ventricles, and those with ventricular imbalance undergoing univentricular repair.ResultsIn the 22 patients undergoing biventricular repair, the septal angle was 0 in 14 patients; the other eight patients having angles ranging from 1 to 36, with a mean angle of 7.4°, and standard deviation of 11.1°.The mean angle in the nine patients with ventricle imbalance was 28.6°, with a standard deviation of 3.04°, and with a range from 26 to 35°. Of those undergoing univentricular repair, two patients died, with angles of 26 and 30°, respectively.ConclusionsThe atrioventricular septal angle derived via multiplanar formatting gives important information regarding the degree of ventricular hypoplasia and imbalance. When this angle is above 25°, patients are likely to have ventricular imbalance requiring univentricular repair.
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Tseng, Chun-Chieh, and Jyh-Bin Yang. "THE BENEFIT EVALUATION FRAMEWORK OF USING PERFORMANCE-BASED CONTRACTING IN URBAN ROAD MAINTENANCE." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 30, no. 2 (February 13, 2024): 133–48. http://dx.doi.org/10.3846/jcem.2024.20491.
Abstract:
Performance-based contracts (PBC) have been adopted increasingly in various countries. However, establishing an objective and convincing benefit evaluation framework to facilitate promotion remains a significant challenge for those who wish to use PBCs. A recent study introduced PBC in the context of daily inspection and repair of urban roads. The pilot program in that study successfully addressed the needs of road users, road maintenance authorities, and contractors. Consequently, this study develops the benefit evaluation framework for this type of PBC for broader applications. The proposed benefit evaluation framework, consisting of one qualitative and eight quantitative performanceevaluation items, calculates the effectiveness of introducing PBC to verify its practicality. The validation results show that qualitative benefit evaluation using the Pavement Condition Index achieves a “satisfactory” rating. For the quantitative benefit evaluation, an overall benefit-cost ratio (BCR) of 5.35 suggests that it is economically viable. The developed benefit evaluation framework can be used as a simple and easy-to-use evaluation tool for other organizations to assess whether to introduce PBC. This study fills this research gap by addressing the use of PBCs in the maintenance of all categories of toll-free roads, and contributes to expanding the application of PBCs in road maintenance services.
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Hrúz, Michal, Martin Bugaj, Andrej Novák, Branislav Kandera, and Benedikt Badánik. "The Use of UAV with Infrared Camera and RFID for Airframe Condition Monitoring." Applied Sciences 11, no. 9 (April 21, 2021): 3737. http://dx.doi.org/10.3390/app11093737.
Abstract:
The new progressive smart technologies announced in the fourth industrial revolution in aviation—Aviation 4.0—represent new possibilities and big challenges in aircraft maintenance processes. The main benefit of these technologies is the possibility to monitor, transfer, store, and analyze huge datasets. Based on analysis outputs, there is a possibility to improve current preventive maintenance processes and implement predictive maintenance processes. These solutions lower the downtime, save manpower, and extend the components’ lifetime; thus, the maximum effectivity and safety is achieved. The article deals with the possible implementation of an unmanned aerial vehicle (UAV) with an infrared camera and Radio Frequency Identification (RFID) as two of the smart hangar technologies for airframe condition monitoring. The presented implementations of smart technologies follow up the specific results of a case study focused on trainer aircraft failure monitoring and its impact on maintenance strategy changes. The case study failure indexes show the critical parts of aircraft that are subjected to damage the most. The aim of the article was to justify the need for thorough monitoring of critical parts of the aircraft and then analyze and propose a more effective and the most suitable form of technical condition monitoring of aircraft critical parts. The article describes the whole process of visual inspection performed by an unmanned aerial vehicle (UAV) with an IR camera and its related processes; in addition, it covers the possible usage of RFID tags as a labeling tool supporting the visual inspection. The implementations criteria apply to the repair and overhaul small aircraft maintenance organization, and later, it can also increase operational efficiency. The final suggestions describe the possible usage of proposed solutions, their main benefits, and also the limitations of their implementations in maintenance of trainer aircraft.
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Sun, Jianzhong, Dan Chen, Chaoyi Li, and Hongsheng Yan. "Integration of scheduled structural health monitoring with airline maintenance program based on risk analysis." Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability 232, no. 1 (November 24, 2017): 92–104. http://dx.doi.org/10.1177/1748006x17742777.
Abstract:
The aerospace industry is striving to reduce the aircraft operating costs while maintaining required safety level. Emerging technologies such as the structural health monitoring to reduce long-term maintenance cost and increase aircraft availability are promoted by the manufacturers. To successfully integrate the structural health monitoring technology into the current maintenance process of modern commercial aviation, a clear definition of the structural-health-monitoring-based maintenance operational concept and the system level requirements is required. This article proposed a structural health monitoring operational concept and the associated maintenance cost modeling and risk assessment methods for the implementation of the structural health monitoring in commercial aviation industry. The developed methodology provides a tool to determine the optimal scheduled structural health monitoring inspection interval and repair decision thresholds for approved scheduled structural health monitoring task. A simulated case study is carried out to demonstrate the structural health monitoring operational concept and how an optimal maintenance strategy can be determined using the proposed methodology. Preliminary results show that the integration of the structural health monitoring into the existing maintenance process can reduce the maintenance cost compared to that of the current practice using the traditional Non-Destructive Evaluation (NDE) techniques while maintaining the risk below an acceptable level.
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Day, Emily P., Benjamin R. Johnston, Stanley F. Bazarek, Justin M. Brown, Nucelio Lemos, Eve I. Gibson, Helaina N. Hurban, et al. "Anatomical Location of the Vesical Branches of the Inferior Hypogastric Plexus in Human Cadavers." Diagnostics 14, no. 8 (April 10, 2024): 794. http://dx.doi.org/10.3390/diagnostics14080794.
Abstract:
We have demonstrated in canines that somatic nerve transfer to vesical branches of the inferior hypogastric plexus (IHP) can be used for bladder reinnervation after spinal root injury. Yet, the complex anatomy of the IHP hinders the clinical application of this repair strategy. Here, using human cadavers, we clarify the spatial relationships of the vesical branches of the IHP and nearby pelvic ganglia, with the ureteral orifice of the bladder. Forty-four pelvic regions were examined in 30 human cadavers. Gross post-mortem and intra-operative approaches (open anterior abdominal, manual laparoscopic, and robot-assisted) were used. Nerve branch distances and diameters were measured after thorough visual inspection and gentle dissection, so as to not distort tissue. The IHP had between 1 to 4 vesical branches (2.33 ± 0.72, mean ± SD) with average diameters of 0.51 ± 0.06 mm. Vesical branches from the IHP arose from a grossly visible pelvic ganglion in 93% of cases (confirmed histologically). The pelvic ganglion was typically located 7.11 ± 6.11 mm posterolateral to the ureteral orifice in 69% of specimens. With this in-depth characterization, vesical branches from the IHP can be safely located both posterolateral to the ureteral orifice and emanating from a more proximal ganglionic enlargement during surgical procedures.
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Uyiomendo, Efosa E., and Markeset Tore. "Subsea maintenance service delivery." Journal of Quality in Maintenance Engineering 21, no. 1 (March 9, 2015): 34–54. http://dx.doi.org/10.1108/jqme-11-2013-0071.
Abstract:
Purpose – The purpose of this paper is to propose a multi-variable analysis (MVA) model for predicting potential delays in the delivery of subsea inspection, maintenance and repair (IMR) services. Design/methodology/approach – Based on data from 351 subsea IMR service jobs executed between 2006 and 2008, a MVA model is proposed for predicting the potential delays in the delivery of IMR services in different plausible scenarios. Findings – A model for predicting the delays in IMR service delivery, based on four practical variables that are readily available during the planning phase, was developed and tested. The factors contributing to delays in petroleum subsea IMR services based on importance are: water depth, weather, job complexity, job uncertainty as well as job complexity mix. Research limitations/implications – The MVA model is developed based on analyzing subsea IMR service jobs performed in the petroleum industry from 2006-2008. The model can be used in the planning stage to predict potential delays in service delivery based on practical variables available. Originality/value – The research proposes a MVA model for predicting delays in service delivery. The model is useful for predicting potential delays in service delivery and for improving the plan based on model analysis results.
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Plyusnina, Ekaterina, and Vera Akristiniy. "Repair strategy for housing stock engineering systems to improve energy efficiency." E3S Web of Conferences 244 (2021): 05023. http://dx.doi.org/10.1051/e3sconf/202124405023.
Abstract:
The article discusses problems of current interest concerning the housing and utility sector associated with increasing the level of comfort of living by constantly improving measures for carrying out planned and un-scheduled repairs and surveys. This work provides a methodology for justi-fying the choice of a repair strategy for engineering systems of water sup-ply and sewerage in the process of operating the housing stock, the imple-mentation of which will contribute to the timely and rational repairs and inspections of buildings engineering systems. This will allow systematical-ly eliminating engineering systems malfunctions, predicting and planning the optimal quantity and chronology of repair and restoration activities by maintaining the technical condition of the engineering system elements within the permissible limits during the standard service life.The main goal of the research in the presented material is to substantiate the methodology for choosing a repair strategy for water supply and sewerage systems dur-ing the operation of apartment buildings.The optimal periodicity for the re-pair of engineering systems depends on the failure rate of elements and the costs associated with the execution of all operational activities.Three op-tions considered for organizing repairs of engineering equipment.Applied in actual practice the technique of choosing the repair strategy of engineer-ing systems for selecting the optimal option to organize repairs of engi-neering equipment.
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Chuang, Ming-Hsi, Li-Hsing Ho, Tzong-Fu Kuo, Shi-Yuan Sheu, Yu-Hao Liu, Po-Cheng Lin, Yu-Chen Tsai, Chang-Huan Yang, Chi-Ming Chu, and Shinn-Zong Lin. "Regenerative Potential of Platelet-Rich Fibrin Releasate Combined with Adipose Tissue–Derived Stem Cells in a Rat Sciatic Nerve Injury Model." Cell Transplantation 29 (January 1, 2020): 096368972091943. http://dx.doi.org/10.1177/0963689720919438.
Abstract:
Sciatic nerve injuries, not uncommon in trauma with a limited degree of functional recovery, are considered a persistent clinical, social, and economic problem worldwide. Accumulating evidence suggests that stem cells can promote the tissue regeneration through various mechanisms. The aim of the present study was to investigate the role of adipose tissue–derived stem cells (ADSCs) and combine with platelet-rich fibrin releasate (PRFr) in the regeneration of sciatic nerve injury in rats. Twenty-four Sprague-Dawley rats were randomly assigned to four groups, a blade was used to transect the left hindlimb sciatic nerve, and silicon tubes containing one of the following (by injection) were used to bridge the nerve proximal and distal ends (10-mm gap): group 1: untreated controls; group 2: PRFr alone; group 3: ADSCs alone; group 4: PRFr + ADSCs-treated. Walking function was assessed in horizontal rung ladder apparatus to compare the demands of the tasks and test sensitivity at 1-mo interval for a total of 3 mo. The gross inspection and histological examination was performed at 3 mo post transplantation. Overall, PRFr + ADSCs-treated performed better compared with PRFr or ADSCs injections alone. Significant group differences of neurological function were observed in ladder rung walking tests in all treated groups compared to that of untreated controls ( P < 0.05). This injection approach may provide a successfully employed technique to target sciatic nerve defects in vivo, and the combined strategy of ADSCs with PRFr appears to have a superior effect on nerve repair.
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Zuckerman, Dror. "Optimal inspection policy for a multi-unit machine." Journal of Applied Probability 26, no. 3 (September 1989): 543–51. http://dx.doi.org/10.2307/3214412.
Abstract:
We consider a machine which generates income at rate I during its operating time. The machine is composed of N independent stochastically failing units. A failure of each one of the units causes a breakdown of the machine.The machine's status (good or failed) is observed continuously, by a controller, at zero cost. In the event of a breakdown, exactly one unit is failed, and a series of inspections is performed, in order to identify the failed unit and the reasons for its failure. At any time along the inspection process only one unit can be tested.An inspection of a given unit is characterized by its cost rate and inspection time. At the end of the inspection process, the failed unit is repaired at a known cost, and a new operating cycle is started.Our objective is to formulate an optimal inspection strategy under two optimality criteria: long-run average net income, and total expected discounted net income.