Seismic Risk Assessment of Buildings in the Extended Urban Region of Athens and Comparison with the Repair Cost

A complete research of seismic risk assessment is presented herein focused on the existing build- ings of the extended urban region of Athens in Greece. The seismic risk assessment is fulfilled by discriminating the current study in two approaches, probable and actual, conducting afterwards between them a comparison analysis. In the first part, a pilot methodology is developed for the seismic loss assessment in monetary terms regarding the buildings damages, consistent with the National Programme for Earthquake Management of Existing Buildings (NPEMEB). The building stock consists of typical building types of Southern Europe and refers to 750,085 buildings (18.80% of buildings in Greece) situated in the entire region of Athens according to the results of the 2000-1 statistical census. A wider research of seismic risk assessment could include direct losses of infrastructures and indirect economic losses. The evaluation of loss due to building damage in a certain region requires an assessment of both seismic hazard and vulnerability of the building stock in the study area. Four different existing damage scenarios are applied for the vulnerability assessment. The results of the seismic risk assessment for the four different aspects of the es- timated damage and the different soil conditions are presented in a map of the study region. The existing vulnerability curves corresponding to defined types of buildings have been derived from the National Technical Chamber of Greece and also from recently developed DPMs. The last DPMs were obtained in a previous research (Eleftheriadou, 2009) from the process of a created damage database after the 7th of September 1999 Parnitha’s earthquake and comprised 180,945 buildings which developed damage of varying degree, type and extent. In the second part of the research, the seismic risk is evaluated from the available data regarding the mean statistical repair/ strengthening or replacement cost for the total number of damaged structures (180,427 buildings) after the same (1999 Parnitha’s) seismic event. Data regarding the compatible (budget approved according to the ministry’s provisions) repair cost has been collected. The structural losses in monetary terms for the 180,427 buildings damaged structures are evaluated equal to 2450.0 Μ€, 1887.8 Μ€ and 2118.9 Μ€ based on the previously mentioned statistical seismic risk data. The statistically derived repair cost for Attica is compared with the results of the economic loss esti- mation for buildings using the aforementioned risk assessment methodology. From the analysis results, the seismic scenario based on the recently developed DPMs (Eleftheriadou, 2009) pre- sented the better correlation (2627.77 M€) with the total statistically evaluated repair cost (2450.02 M€). It is important to stress that the inclusion of the coefficient parameter S overes- timates significantly the seismic losses. The last result should be taken into consideration in future risk researches. The comparison of the estimated economic loss with the statistical repair cost calibrates the reliability of the commonly used risk assessment method and serves in the im- provement of seismic security prioritizing the criteria for seismic rehabilitation programmes of existing buildings.

Estimation of Load-Induced Damage and Repair Cost in Post-Tensioned Concrete Rocking Walls

Post-tensioned concrete rocking walls might be used to avoid severe seismic damage at the base of structural walls, decrease residual drift, and lessen post-earthquake repair costs. The prediction of load-induced damage to the rocking wall resulting from seismic loading can provide an extremely valuable tool to evaluate the status and safety of structural concrete walls following earthquakes. In this study, the behavior and the damage state of monolithic, self-centering, rocking walls, as a new type of concrete rocking wall, are investigated. The nonlinear mechanical behavior of the wall is first modeled numerically, and subsequently the mechanical parameters from the numerical simulation are used to generate the local damage index. The results from the damage index model are compared with the full-scale test results, confirming the viability of the numerically based damage index method for estimating the seismically induced damage in concrete walls. Moreover, the estimated damage can be utilized as a qualitative and quantitative scale to assess the status of the wall following seismic loading events.Finally, an equation is proposed to estimate the repair cost based on the predicted damage state for the studied structural system.

Optimal replacement policy of products with repair-cost threshold after the extended warranty

The reliability of the product sold under a warranty is usually maintained by the manufacturer during the warranty period. After the expiry of the warranty, however, the consumer confronts a problem about how to maintain the reliability of the product. This paper proposes, from the consumer's perspective, a replacement policy after the extended warranty, under the assumption that the product is sold under the renewable free replacement warranty (RFRW) policy in which the replacement is dependent on the repair-cost threshold. The proposed replacement policy is the replacement after the extended warranty is performed by the consumer based on the repair-cost threshold or preventive replacement (PR) age, which are decision variables. The expected cost rate model is derived from the consumer's perspective. The existence and uniqueness of the optimal solution that minimizes the expected cost rate per unit time are offered. Finally, a numerical example is presented to exemplify the proposed model.

Warranty Cost Model Based on Optimal Preventive Maintenance Operations for Repairable Products

Most warranty cost models based on preventive maintenance operations are assumed that products improve at each preventive maintenance(PM)operation and the failure rate is reduced to the failure rate of new products or to some specified level.To make warranty cost models more suitable to real operations,a modeling method of the PM warranty cost was proposed with the situation where each PM operation slowed the rate of product degradation.A warranty cost model was built on PM operations.On the basis of the cost model,both without and with reliability limit PM warranty policy,algorithms were presented to derive the optimal PM number and the optimal PM interval with an objective of minimizing expected total warranty cost over a finite warranty period.Finally,to demonstrate the feasibility of the presented modeling method,Weibull distribution cases were tested by numerical simulations.The simulation results indicate that the proposed modeling method is feasible and valid for resolving the optimal solution of the product warranty cost.

Cost-Benefit Assessment of Inspection and Repair Planning for Ship Structures Considering Corrosion Model Uncertainty

Owing to high costs and unnecessary inspections necessitated by the traditional inspection planning for ship structures, the risk-based inspection and repair planning should be investigated for the most cost-effective inspection. This paper aims to propose a cost-benefit assessment model of risk-based inspection and repair planning for ship structures subjected to corrosion deterioration. Then, the benefit-cost ratio is taken to be an index for the selection of the optimal inspection and repair strategy. The planning problem is formulated as an optimization problem where the benefit-cost ratio for the expected lifetime is maximized with a constraint on the minimum acceptalbe reliability index. To account for the effect of corrosion model uncertainty on the cost-benefit assessment, two corrosion models, namgly, Paik＇ s model and Guedes Soares＇ model, are adopted for analysis. A numerical example is presented to illustrate the proposed method. Sensitivity studies are also providet. The results indicate that the proposed method of risk-based cost-benefit analysis can effectively integrate the economy with reliability of the inspection and repair planning. A balance can be achieved between the risk cost and total expected inspection and repair costs with the proposed method, which is very. effective in selecting the optimal inspection and repair strategy. It is pointed out that the corrosion model uncertainty and parametric uncertaintg have a significant impact on the cost-benefit assessment of inspection and repair planning.

Cost effective use of mosquito net mesh in inguinal hernia repair

Mesh hernia repair is one of the commonest open techniques of inguinal hernia repair.The main limiting factor in the use of new meshes is the cost.We carried out a prospective randomized double blind study and comprising of a hundred patients with 100 inguinal hernias admitted consecutively for elective surgery,divided into the polypropylene mesh(PPM)group and the mosquito net mesh(MNM)group each containing fifty patients.All cases were completed successfully and results revealed no difference in two groups.The results of the present study,in consistent with the published literature,reveal that the cheap indigenous mosquito mesh,which has similar properties of an imported mesh,can be safely used for tension-free inguinal hernia repair in adults.Further trials with a larger number of patients and longer follow-ups are justified and recommended.

基于改进GM(1,1)模型的变电站检修运维费用预测

针对变电站因设备的缺陷而引起的全寿命周期成本(life cycle cost,LCC)中检修运维费用拨付波动现象,分别采用传统的灰色GM(1,1)模型和组合改进的灰色GM(1,1)模型,对未来3年地市A的变电站检修运维费用进行预测,优化现有的成本拨付策略。结果表明,2种模型的预测精度等级均为一级,但改进后模型的平均相对误差及后验差比值均低于传统模型,说明改进模型比传统模型具有更高的预测精度,能够更好地预测变电站的检修运维费用。最后,利用改进的预测模型对某地市A的2019—2021年变电站检修运维费用进行预测。

心理资本对大学生创业失败修复的影响——一个有调节的中介效应模型

作为大学生开展创业活动的重要驱动因素,心理资本是否对大学生创业失败修复也产生重要影响,是学界关注的研究问题。对全国632份创业失败大学生问卷调查数据的分析发现:心理资本对大学生创业失败修复有正向促进作用,能正向预测其创业失败修复水平;失败学习和恢复导向在其中起中介作用;经济成本负向调节心理资本通过失败学习和恢复导向影响大学生创业失败修复的程度。促进大学生创业失败修复,可从营造宽容创业失败氛围、切实提升大学生心理资本、构建大学生创业失败经济补偿机制和大学生加强失败学习准备等方面入手。

复合树脂多层修复技术与复合树脂直接粘接修复技术在前牙间隙美学修复中的效果对比

目的:对比分析复合树脂多层修复技术与复合树脂直接粘接修复技术在前牙间隙美学修复中的效果。方法:纳入笔者医院2020年6月-2021年6月收治的98例(共104颗患牙)前牙间隙患者作为研究对象,按照随机数表法分为A组和B组,各49例。A组患者接受复合树脂多层修复技术,B组患者接受复合树脂直接粘接修复技术。对比两组修复效果、美学效果和治疗总费用,比较两组修复前和修复30d后、6个月后的咬合力、咀嚼效率和焦虑自评量表(Self-ratinganxietyscale,SAS)、抑郁自评量表(Self-rating depression scale,SDS)评分。结果:修复30 d后,A组优秀率高于B组(P<0.05),两组良好率和不良率比较无统计学意义(P>0.05)。修复6个月后,A组优秀率和不良率均高于B组(P<0.05),两组良好率比较无统计学意义(P>0.05)。患者的咬合力在时间、交互作用上差异有统计学意义(P<0.05),在组间作用上差异无统计学意义(P>0.05)。患者的咀嚼效率在时间、组间、交互作用上差异均有统计学意义(P<0.05)。修复6个月后,两组患者咬合力和咀嚼效率均较修复30d后和修复前升高,且A组咬合力和咀嚼效率高于B组(P<0.05)。A组修复后的边缘密合性、颜色匹配性、修复体崩裂、继发龋损、形态匹配、修复体脱落和牙龈健康评分均低于B组(P<0.05)。患者的SAS评分和SDS评分在时间、组间、交互作用上有统计学意义(均P<0.05)。修复30d后和修复6个月后,两组患者SAS和SDS评分均较修复前降低,且A组低于B组(P<0.05)。A组治疗总花费高于B组(P<0.05)。结论:与复合树脂直接粘接修复技术相比,在前牙间隙美学修复中应用复合树脂多层修复技术可取得更佳的修复效果,有助于恢复患者咬合力和咀嚼功能,使患者获得良好美学效果,改善其心理状态。但治疗总花费相对较高,临床治疗需结合患者经济情况选择合适治疗方案。

Optimum Maintenance Policy for a One-Shot System with Series Structure Considering Minimal Repair

One-shot systems such as missiles and extinguishers are placed in storage for a long time and used only once during their lives. Their reliability deteriorates with time even when they are in storage, and their failures are detected only through inspections for their characteristics. Thus, we need to decide an appropriate inspection policy for such systems. In this paper, we deal with a system comprising non-identical units in series, where only minimal repairs are performed when unit failures are detected by periodic inspections. The system is replaced and becomes “as good as new” when the nth failure of the system is detected. Our objective is to find the optimal inspection interval and number of failures before replacement that minimize the expected total system cost per unit of time.

基于机器学习法的高速公路桥涵小修工程费用模型预测

基于陕西省11条高速公路2008~2015年桥涵小修工程量清单历史数据,采用机器学习算法,以组成桥涵各构件的小修费用作为因变量,研究桥涵小修费用预测模型。通过灰色关联度模型分析桥涵小修费用的影响因素,采用皮尔逊相关系数检验法对各影响因素进行多重共线性检验,筛选出解释变量,使用岭回归和Lasso回归对桥涵各构件小修费用模型进行回归分析,得到桥涵小修总费用预测模型。结果表明:桥涵小修工程费用的影响因素主要有通车年限、桥梁(涵洞)长度、年平均当量轴次、桥涵所处地区的年均降雨量和温度及车道数;基于模型预测所依托高速公路2016~2017年桥涵小修费用,并与该年度实际费用进行Wilcoxon符号秩检验,检验结果均大于0.05,验证了机器学习法预测桥涵小修工程费用模型的有效性,预测结果能为分配养护费用、提高养护决策水平提供合理建议。

Transabdominal Pre-Peritoneal Mesh for Inguinal Hernia Repair with External Fixation versus Mesh Stapling

Background: It is unknown whether stapling the mesh affects recurrence rate, incidence of neuralgia, and port-site hernia. We chose to fix it to the exterior reducing port size, cost and pain, at the same comparing this with traditional mesh stapling. Methods: We conducted a prospective trial for laparoscopic TAPP inguinal hernia repair on 120 patients in which we fixed the mesh to the anterior abdominal wall using either two prolene threads that passed to the exterior and tied in place or traditional mesh stapling. Results: The operative time is ranged from 35 to 70 minutes for external fixation, 30 to 60 minutes for mesh stapling, and 4 to 51 months for follow-up, and no recurrence occurred in both groups during the procedure. Two cases with post TAPP pain in mesh stapling patients are discussed with reduction of the cost and port size in external fixation patients. Conclusion: It is not necessary to secure the mesh during laparoscopic TAPP inguinal hernia repair from the interior and it is fixed only to the exterior allowing a reduction in size of the ports and considerable reduction in cost with elimination of TAPP associated post operative pain.

航材共享对可修理备件保障成本的影响研究

针对航空业竞争加剧,可修理件资金占比较大的现状,探索通过航材共享降低可修理件保障成本的可行性。在对可修理航材备件特点及保障成本构成分析的基础上,结合共享模式下备件保障需求产生机制,建立航材共享保障成本模型,并以自主供应为对照,采购单价为影响因素,保障率为约束,将两种备件供应策略下的最小保障成本做差,建立差值成本模型,用蒙特卡洛法对备件故障时间及维修周转时间进行模拟,通过案例分析采购单价变化对差值成本的影响。结果表明:差值成本与备件采购单价正相关,且机队规模扩大将增加差值成本增幅,即航材共享在备件采购单价较高,购买成本较大时,优势明显,而机队规模扩大将增加航材共享保障成本优势。

Optimum Maintenance and Availability of Series Systems Subject to Imperfect Repair

Optimum maintenance and availability of a series system whose components are subject to imperfect repairs are studied in this paper. Imperfect corrective maintenance is treated in a way that after it the life of each component in the system will be decreased to a fraction of its immediately previous one and the repair time will be increased to a multiple of the one immediately preceding it, where successive failure free times are independent and so are successive repair times. Under such an assumption, the limiting system availability, mean time between system failures or repairs are derived based on some related results. A numerical example is presented to compare with Barlow and Proschan's availability model. Two classes of maintenance cost models are proposed and the optimum maintenance policies are also discussed for series system with n components in this paper.

工程造价行业改革背景下企业定额编制探索——以劳动消耗量定额编制为例

工程造价行业推行市场化改革,政府逐步取消发布预算定额,鼓励行业企业自主编制预算定额,然而广大施工企业普遍存在定额编制能力不足、编制经验欠缺的问题。以建筑施工企业用于投标报价的企业工程预算定额为研究对象,全面梳理了企业工程预算定额的编制流程。以地下排水管道非开挖修复工程定额编制为例,详细分析了劳动消耗量定额的编制方法,并演示了劳动消耗量定额数据测定方法。研究指出,企业定额的编制既要遵循科学的编制流程,采用科学的编制方法,又要充分考虑施工企业的工程实践经验。

航空发动机起动机送修决策方法

针对飞机维修手册中对空气涡轮起动机送修决策描述的不足,提出一种起动机送修及维护的定量决策方法。该方法依据某型发动机起动机的可靠性数据建立有效的可靠性统计模型,并以此为基础引入可靠度1阶导数概念制定符合本机队的空气涡轮起动机软时限;在进一步分析空气涡轮起动机维护成本的构成后,针对其中轴承失效所带来的高昂换修成本问题给出解决方案;从部件换修成本和延误成本角度出发建立期望损失模型,以经济最优为目标给出定量的起动机维护检查间隔;以某航空公司机队的起动机使用数据为例,计算起动机送修软时限和滑油检查间隔分别为26960和1915飞行小时。结果表明:该方法依据部件可靠性和维护成本数据能够制定适用于本机队的起动机软时限和维护检查间隔,具有一定的工程意义和使用价值。

浅谈古建筑易地修缮工程的造价管理控制

随着我国社会经济发展以及“文化自信”的提出,古建筑保护也日益受到重视。从福建省某校历史建筑易地修缮工程出发,指出古建筑异地修缮工程在勘察设计阶段、招投标阶段、施工阶段、竣工结算阶段等存在的问题,分析全过程造价管理的各阶段事项,提出应通过评估损毁程度、制定合理施工方案、加强施工过程中的造价管理和规范结算审计过程等措施,以达到有效控制古建筑易地修缮工程造价的目的。采用异地修缮保护的方式可以使古建筑新生,有利于保护和传承文化遗产,也为今后开展同类型修缮工程提供了现实参考。

Artificial neural network-based repair and maintenance cost estimation model for rice combine harvesters

This research proposes an artificial neural network(ANN)-based repair and maintenance(R&M)cost estimation model for agricultural machinery.The proposed ANN model can achieve high estimation accuracy with small data requirement.In the study,the proposed ANN model is implemented to estimate the R&M costs using a sample of locally-made rice combine harvesters.The model inputs are geographical regions,harvest area,and curve fitting coefficients related to historical cost data;and the ANN output is the estimated R&M cost.Multilayer feed-forward is adopted as the processing algorithm and Levenberg-Marquardt backpropagation learning as the training algorithm.The R&M costs are estimated using the ANN-based model,and results are compared with those of conventional mathematical estimation model.The results reveal that the percentage error between the conventional and ANN-based estimation models is below 1%,indicating the proposed ANN model’s high predictive accuracy.The proposed ANN-based model is useful for setting the service rates of agricultural machinery,given the significance of R&M cost in profitability.The novelty of this research lies in the use of curve-fitting coefficients in the ANN-based estimation model to improve estimation accuracy.Besides,the proposed ANN model could be further developed into web-based applications using a programming language to enable ease of use and greater user accessibility.Moreover,with minor modifications,the ANN estimation model is also applicable to other geographical areas and tractors or combine harvesters of different countries of origin.

修理的买卖法构造

我国买卖法虽未明文明确“修理优先”,但此项结构性原则不仅可从法政策层面推导,也能借助私法规范之间的脉络互动得以呈现。修理作为补正履行手段,专为物的瑕疵量身打造。买受人支出的运输费用构成补正费用,应由出卖人负担,买受人擅自修理而支出必要费用,出卖人应依无因管理法则返还。《买卖合同司法解释》第16条并非费用返还的规范依据,而是买受人主张损害赔偿的请求权基础。