Load Testing in Bridge Maintenance

Highway bridges are a crucial component in road transportation networks.These bridges must be maintained according to usage requirements regularly.Test results must be considered before devising a maintenance plan.Load testing is a vital method of assessing the quality and performance of highway bridges.The outcomes of these tests facilitate the formulation of maintenance plans.This article examines the definition of load testing,its significance,and the process of execution,with the goal of providing support for bridge inspection and maintenance.

Availability-based maintenance optimization under unequal inspection period and imperfect repair

Taking the multi-component system as research object, a maintenance optimization model based on the unequal inspection period and imperfect repair is established by considering the requirement of expected availability for improving the system＇s availability. An age reduction factor is used to describe the effect of imperfect repair, and the modelling approach for the unequal inspection period is proposed. Unavailable situations are classified into three kinds of independent cases, and the availability is calculated accordingly. Based on the analysis of the relationship between the unavailable cases and the unequal inspection period, an optimization model under imperfect repair is established to optimize the system＇s expected availability. A case study of a wind turbine is provided, and three key components, i.e. gearbox, generator and spindle, are considered. The optimization results of the unequal inspection period model and the equal inspection period model are compared. The results show that the unequal inspection period model based on availability can update the maintenance plan so as to optimize maintenance activities and improve the system＇s availability.

Joint optimization of inspection, maintenance, and spare ordering policy considering defective products loss

This paper proposes a joint inspection-based maintenance and spare ordering optimization policy that considers the problem of integrated inspection,preventive maintenance,spare ordering,and quality control for a four-state single-unit manufacturing system.When an inspection detects a minor defect,a second phase inspection is initiated and a regular order is placed.Product quality begins to deteriorate when the system undergoes a severe defect.To counter this,an advanced replacement of the minor defective system is carried out at the Jth second phase inspection.If a severe defect is recognized prior to the Jth inspection,or if system failure occurs,preventive or corrective replacement is executed.The timeliness of replacement depends on the availability of spare.We adopt two modes of ordering:a regular order and an emergency order.Meanwhile,a threshold level is introduced to determine whether an emergency order is preferred even when the regular order is already ordered but has not yet arrived.The optimal joint inspection-based maintenance and spare ordering policy is formulated by minimizing the expected cost per unit time.A simulation algorithm is proposed to obtain the optimal two-phase inspection interval,threshold level and advanced replacement interval.Results from several numerical examples demonstrate that,in terms of the expected cost per unit time,our proposed model is superior to some existing models.

Evaluating and Improving the Effectiveness of Vehicle Inspection and Maintenance Programs: A Cost-Benefit Analysis Framework

Motor vehicle inspection and maintenance (I/M) programs are designed to identify high-emitting vehicles and mitigate their impacts on air quality and climate. I/M programs have been traditionally ranked superior among various vehicle emission control measures by the results of cost-benefit analysis, based on the assumption that these programs will achieve the targeted emission reduction outcomes. However, the actual effects of I/M programs may be greatly uncertain and when this uncertainty is taken into account, these programs may become suboptimal. This study develops a new a cost-benefit analysis framework that links various program design consideration, such as program participation rate, identification rate and effective repair rate, to the public health benefits as well as costs of the programs. This framework helps decision makers to investigate minimum implementation requirements that at least ensure the benefits are greater than the costs of implementing the programs in order to improve the overall effectiveness of the I/M programs. To illustrate the applications of the framework, it was applied to a particulate matter oriented I/M program targeting all diesel-fueled vehicles in the city of Bangkok, Thailand, a large metropolitan area that has been suffering from severe ambient PM pollution mainly attributable to its wide use of diesel-fueled vehicles and motorcycles. It was found that the health benefits achieved from the program are sensitive to several key program design elements, including participation rate and problem vehicle identification rate, fraction of effective repairs and illegal operation rate. Other variables, such as the testing cut-points and vehicle population growth rate, only have modest effects on the overall emission reduction and consequent health benefits. Overall, the performance of multiple variables associated with I/M program design needs to be improved simultaneous in order to achieve the targeted benefits of the program.

Doing a Good Job in Inspection and Maintenance of Facilities and Equipments in Bulk Curing Barn

Due to the limited management funds and insufficient management efforts,curing barns in traditional tobacco area are outdated and equipments are seriously damaged,which affects the normal operation and increases the maintenance cost of bulk curing barns,bringing adverse effects on tobacco leaf curing in the coming year and the sustainable development of tobacco industry in the future.To ensure the normal operation of curing barns and effectively prolong the service life of curing barns during tobacco leaf curing,we should do a good job in the publicity of management and maintenance,improve the system of management and maintenance,raise funds for management and maintenance,inspect facilities and equipments,carefully maintain equipments in curing barn and strictly perform examination and inspection.

Strategies for Project-oriented Teaching Design of Automobile Inspection and Maintenance Course

Automobile Inspection and Maintenance Course is relatively practical and professional.Therefore,teachers need to provide students with opportunities for practice as much as possible,so that students can realize the integration of theory and practice,improve teaching efficiency.Project-oriented teaching design can enable students to participate in the practical training and maintenance of automotive engines,which helps students understand the theories in the book.This article mainly analyzes the strategies for teaching design of project-oriented Automobile Inspection and Maintenance Course.

Analysis of Maintenance and Inspection Status of Aeronautical Machinery and Improvement Countermeasures

In the daily operation process of airlines,aviation machinery maintenance and inspection work play an important role.At present,the quality of life of the people in our country is constantly improving.In daily travel,we have not only used cars,trains and other means of transportation,but also started to choose airplanes as the first choice in a higher frequency.In recent years,with the improvement of living standards,more and more people choose to travel during holidays.Therefore,the traffic volume of aviation aircraft is increasing year by year,but it also increases the risk of aviation aircraft failure,so it is particularly important to do a good job in the maintenance and inspection of aviation machinery.In this paper,according to the current situation of aviation machinery maintenance and inspection,put forward targeted improvement measures to ensure the safety and stability of China's aviation aircraft operation.

Condition-based Maintenance Optimization for Gamma Deteriorating Systems under Performance-based Contracting

With the further development of service-oriented,performance-based contracting(PBC)has been widely adopted in industry and manufacturing.However,maintenance optimization problems under PBC have not received enough attention.To further extend the scope of PBC’s application in the field of maintenance optimization,we investigate the condition-based maintenance(CBM)optimization for gamma deteriorating systems under PBC.Considering the repairable single-component system subject to the gamma degradation process,this paper proposes a CBM optimization model to maximize the profit and improve system performance at a relatively low cost under PBC.In the proposed CBM model,the first inspection interval has been considered in order to reduce the inspection frequency and the cost rate.Then,a particle swarm algorithm(PSO)and related solution procedure are presented to solve the multiple decision variables in our proposed model.In the end,a numerical example is provided so as to demonstrate the superiority of the presented model.By comparing the proposed policy with the conventional ones,the superiority of our proposed policy is proved,which can bring more profits to providers and improve performance.Sensitivity analysis is conducted in order to research the effect of corrective maintenance cost and time required for corrective maintenance on optimization policy.A comparative study is given to illustrate the necessity of distinguishing the first inspection interval or not.

Farmers’ Practices for the Orchard’s Maintenance and Post-Harvest Treatment of Cocoa in Infiltrated Classified and Unclassified Zone of Méagui (South-West, Côte d’Ivoire)

An important part of Ivorian cocoa production comes from infiltrated classified forests. The objective of this study is to investigate orchard maintenance and post-harvest cocoa treatment practices used by cocoa farmers in infiltrated classified and unclassified areas of Méagui. To do this, 110 producers in two localities of the said zone were individually interviewed from February to April 2022, using a declarative questionnaire. It was found that cocoa orchards in the zone are aging. Nearly 68.55% of producers were heirs and 58.33% of those interviewed were under 46 years of age, with an average age of 43 years. Nearly 84.55% of the producers surveyed mainly use chemical insecticides to control the pests of greatest concern in these localities. Regarding the frequency of insecticide treatments, 11.82% of producers make 1 to 2 applications a year, 29.09% make 3 to 5 applications a year, and 43.64% make at least 6 applications a year. The active substances of the most used products belong to 99% of the Neonicotinoid and Pyrethroid families. Regarding cocoa harvesting and post-harvest operations, 93.64% of the producers carry out a single harvest/month;all do the shelling with mini machetes. Beans are fermented mainly in black plastic tarpaulins or in bags, for a period of 3 to 5 days (65.45%). Drying is done almost entirely (91.82%) on the black plastic tarp. This study shows that cocoa farmers in the areas surveyed do not respect the recommendations issued on phytosanitary practices and post-harvest treatment of cocoa. This non-compliance with the standards of good practices prescribed is particularly more accentuated in the locality located in infiltrated classified zone. It would, therefore, be judicious to revise or redefine the phytosanitary recommendations and carry out sensitization and training-follow-up programs for producers in this important cocoa production area of C?te d’Ivoire.

Farmers’ Practices for the Orchard’s Maintenance and Post-Harvest Treatment of Cocoa in Infiltrated Classified and Unclassified Zone of Méagui (South-West, Côte d’Ivoire)

An important part of Ivorian cocoa production comes from infiltrated classified forests. The objective of this study is to investigate orchard maintenance and post-harvest cocoa treatment practices used by cocoa farmers in infiltrated classified and unclassified areas of Méagui. To do this, 110 producers in two localities of the said zone were individually interviewed from February to April 2022, using a declarative questionnaire. It was found that cocoa orchards in the zone are aging. Nearly 68.55% of producers were heirs and 58.33% of those interviewed were under 46 years of age, with an average age of 43 years. Nearly 84.55% of the producers surveyed mainly use chemical insecticides to control the pests of greatest concern in these localities. Regarding the frequency of insecticide treatments, 11.82% of producers make 1 to 2 applications a year, 29.09% make 3 to 5 applications a year, and 43.64% make at least 6 applications a year. The active substances of the most used products belong to 99% of the Neonicotinoid and Pyrethroid families. Regarding cocoa harvesting and post-harvest operations, 93.64% of the producers carry out a single harvest/month;all do the shelling with mini machetes. Beans are fermented mainly in black plastic tarpaulins or in bags, for a period of 3 to 5 days (65.45%). Drying is done almost entirely (91.82%) on the black plastic tarp. This study shows that cocoa farmers in the areas surveyed do not respect the recommendations issued on phytosanitary practices and post-harvest treatment of cocoa. This non-compliance with the standards of good practices prescribed is particularly more accentuated in the locality located in infiltrated classified zone. It would, therefore, be judicious to revise or redefine the phytosanitary recommendations and carry out sensitization and training-follow-up programs for producers in this important cocoa production area of C?te d’Ivoire.

DELAY-TIME MODEL BASED ON IMPERFECT INSPECTION OF AIRCRAFT STRUCTURE WITHIN FINITE TIME SPAN

According to the failure characteristics of aircraft structure, a delay-time model is an effective method to optimize maintenance for aircraft structure. To imitate the practical situation as much as possible, imperfect inspections, thresholds and repeated intervals are concerned in delay-time models. Since the suggestion by the existing delay-time models that the inspections are implemented in an infinite time span lacks practical value, a de- lay-time model with imperfect inspection within a finite time span is proposed. In the model, the nonhomogenous Poisson process is adopted to obtain the renewal probabilities between two different successive inspections on de- fects or failures. An algorithm is applied based on the Nelder-Mead downhill simplex method to solve the model. Finally, a numerical example proves the validity and effectiveness of the model.

Optimization of post-warranty sequential inspection for second-hand products

This paper considers an optimal sequential inspection schedule for a second-hand product after that the free nonrenewable warranty is expired. The length of warranty is prespecified and during the warranty period, the product is minimally repaired by the dealer when it fails. Following the expiration of the non-renewing warranty, the product is inspected and upgraded sequentially a fixed number of times at the expenses of the customer.At each inspection, the failure rate of the product is reduced proportionally so that the product is upgraded. The product is assumed to deteriorate as it ages and the replacement of the product occurs when a fixed number of inspections are rendered. In addition,the intervals between two successive inspections are assumed to decrease monotonically. The main objective of this paper is to determine the optimal improvement level to upgrade the product at each inspection so that the expected maintenance cost during the life cycle of the product is minimized from the perspective of the customer. Under the given cost structures, we derive an explicit formula to obtain the expected maintenance cost incurred during the life cycle of the product and discuss the method to find the optimal level of the improvement analytically in case the failure times follow the Weibull distribution. Numerical results are analyzed to observe the impact of relevant parameters on the optimal solution.

Periodical Inspections and Delay Replacement Model Based on Age Preventive Replacement Policy

Periodical inspections and an age-based preventive replacement( APR) model were proposed based on a two-stage failure process for a single component system. Inspection activities were performed at regular intervals. Once the system was identified to be at defective state by inspection,a maintenance decision needed to be made that whether to replace the defective system immediately or wait till the preset APR time. So a threshold was introduced into the model and called as inspection-based preventive replacement( IPR) threshold. If the distance from the defect identification point to the APR time was longer than the threshold, a preventive replacement( PR) action was made; otherwise PR action was to wait till the APR time. Two models were proposed and compared,and a numerical example was conducted to illustrate the applicability of the model.

Virtual Reality Technology Applied on Maintenance of Painted Walls of Buildings

In a building, the paint coating applied to interior walls conveys their aesthetic character and also performs an important function of protection. It is a construction component which is exposed to agents of deterioration related to its use, needing the regular evaluation of its state of repair. The completed model supports the performance of such periodic inspections and the monitoring of interior wall maintenance, using Virtual Reality (VR) technology. Used during an inspection visit, the application allows users to consult a database of irregularities, normally associated with paint coating, classified by the most probable causes and by recommended repair methodologies. In addition, with this model, a chromatic scale related to the degree of deterioration of the coating, defined as a function of the time between the dates of the application of the paint and the scheduled repainting, can be attributed to each element of coating monitored. This use of VR technology allows inspections and the evaluation of the degree of wear and tear of materials to be carried out in a highly direct and intuitive manner. The computer application has a positive contribution to make in the field of construction, using as it does Information Technology (IT) tools which give access to innovative technology with it capacity for interaction and visualization.

Inspection Models Considering the Overlapping of Inspection Span and Failure Downtime

In the literature, many works on determining inspection interval by the delay time concept generally assumed that the time of inspection span and the time of failure renewal are negligible. However, in realistic cases, the above time should not be neglected for both the time itself and its effect. In order to model the effect of the possible overlapping of inspection span with failure downtime on determining the optimal inspection interval, we propose a block-based inspection model for a single component-based on delay time concept. We further compare this model with the age-based model to show the practical sense. The developed models are also demonstrated by numerical examples.

Two-Stage Inspection Model Based on a Three-Stage Failure Process

As the non-periodic inspections are common in practice,a two-stage inspection model based on a three-stage failure process is proposed. The two-stage inspection means that the system is inspected with the first inspection interval T_1 and the second inspection interval T_2. Because of the three color schemes commonly used in industry,three stages are divided by the system lifetime:normal, minor defective and severe defective stages. Upon the failure of the system,replacement is carried out. Maintenance is done once identifying the severe defective stage. However,when the minor defective stage is identified by the second inspection interval T_2,action of halving the subsequent inspection interval is adopted.Otherwise,no action is required. Our objective function is to optimize the inspection intervals so as to minimize the expected cost per unit time. Finally,a numerical example is presented to illustrate the effectiveness of the proposed model.

Subsea Maintenance Service Delivery:Mapping Factors Influencing Scheduled Service Duration

The oil and gas （O＆G） industry on the Norwegian continental shelf （NCS） leads the world in terms of the number of subsea O＆G installations. Ensuring the dependability of these assets is critical. Non-intrusive inspection, maintenance and repair （IMR） services are therefore needed to reduce risks. These services are planned and executed using a mono-hull offshore vessel complete with remotely operated vehicles （ROVs）, a module handling system and an active heave compensated crane. Vessel time is shared between competing jobs, using a prioritized forward-looking schedule. Extension in planned job duration may have an impact on O＆G production, service costs and health, safety, and environmental （HSE） risks. This paper maps factors influencing the job schedule efficiency. The influence factors are identified through reviews of literature as well as interviews with experts in one of the large IMR subsea service providers active on the Norwegian Continental Shelf. The findings show that the most obvious factors are weather disruption and water depth. Other factors include job complexity, job uncertainty, IMR equipment availability, as well as the mix of job complexity.

Building Maintenance Supported on Virtual Reality Environments： Roofs and Walls

The paper presents the description of a research work that has its main objective as the development of a technological tool for supporting building maintenance with resort to new information and visualization technologies. Three main components of the building were analyzed： roof, facades and interior walls. The ceramic tile roof covering constitutes a component of the building envelope and fulfils an important function in its performance, namely in its protection against the permeation of moisture and rain water. Facade coating plays a significant role in the durability of buildings, since it constitutes the exterior layer that ensures wall protection against aggressive actions of physical, chemical or biological nature. The paint coating, applied to interior walls while improving their aesthetic character, performs an important function of protection against deterioration agents related to building use. A survey was conducted of the main anomalies that occur in these components, their respective causes and the adequate interventions, in order to plan maintenance strategies. The collected information serves as a basis for the implementation of applications using interactive visualization technologies to support the planning of building maintenance. During this work, the basic knowledge related to the materials, the techniques of rehabilitation and conservation and the planning of maintenance is outlined and discussed. In addition, methods of interconnecting this knowledge with the virtual applications were explored. The implemented prototypes were tested in real cases. This research work provides an innovative contribution to the field of maintenance, supported by emergent virtual reality technology.

Risk Analysis： A Methodology Applicable to the Building Inspection

The lack of care related to maintenance management is directly linked to the absence of plans for maintenance of buildings. Because of that, there is a big incidence of building accidents caused by the negligence of managers and the lack of investment. The research has shown that, although building inspection is a consolidated building maintenance tool, managers do not prepare their building maintenance plan, nor use building inspection as a tool, leading the buildings to the premature obsolescence. The research calls attention to the building inspection technique that can be used to evaluate building maintenance and conservation. It is also a tool for analysis and investment planning based on actions to solve failures and anomalies that might come out during the building inspection. Those failures and anomalies are classified according to their degree of risk, determining the technical priorities of the investment adjustment in the maintenance plan. The paper presents a risk analysis methodology which classifies inspect elements in a building, determining the priority order of services to be executed on a scale from minimum risk （1） to imminent risk （5）. The method shows a tool for building inspection, and it serves as a guideline for building maintenance interventions.

有Bernoulli检修与顾客进入控制策略的M/G/1可修排队的可靠性

本文研究一个具有Bernoulli检修与顾客进入控制策略的M/G/1可修排队模型,其中服务台在服务顾客期间可能发生故障.Bernoulli检修与顾客进入控制策略是指每当系统变空时依概率p(0≤p≤1)进入检修,或者依概率(1−p)不进入检修而是等待下一个顾客进入系统后直接开始服务,而且在系统的检修期内至多允许N个顾客进入.运用更新过程理论、全概率分解技术与拉普拉斯变换工具,我们对系统的一些可靠性指标进行了讨论,例如时刻t服务台处于故障状态的概率、在(0,t]内服务台的平均失效次数等等.最后通过数值计算研究了一些系统参数对系统可靠性指标的影响.