Optimal Replacement of Granite Modified with Ife Iron and Steel Slag on Strength Properties of Concrete

Steel is produced from iron ore and purification of metal scrap, leading to manufacture of hundreds of tonnes of steel slag each year. This study investigated the optimum replacement of granite with Ife Iron and Steel Nigeria Limited (ISN) slag that produce maximum Compressive Strength (CS), Split Tensile Strength (STS) and Flexural Strength (FS) of concrete using Response Surface Methodology (RSM) from Design Expert Version 7.0. The outcome of the study showed that the optimum replacement of granite with ISN was 28.85% ISN at 0.47 W/C.

Reliability evaluation of m-consecutive- k, l-out-of-n: F system subjected to shocks

In this paper, we propose a shock model for an m-consecutive- k, l-out-of- n: F system. This paper presents a reliability analysis of an m-consecutive- k, l-out-of- n: F system subjected to shocks that destroy a random number of components. One of the main random variables is the number of components affected by successive shocks. Phase-type distributions have been used to model the intervals between successive shocks. The main objective of this study is to show how phase-type distributions can be used to determine the reliability of m-consecutive- k, l-out-of- n: F systems subjected to shocks, which destroy a random number of components. Consideration is given to the optimal replacement time problem, which addresses the minimization of the total long-run average cost per unit time.

Cataloging of Unit Replacement Based on Long Run Repair Average Cost Rate (ACR) Based on Weibull Distribution Model

Large amounts of money are lost each year in the real-estate industry because of poor schedule and cost control, In Industry the investigated failure and repair pattern, reliabilities of generators, compressors, turbines, using simple statistical tools and simulation techniques. The repair duration is divided into the 1) Major repair 2) Minor repair, In major repair having (repair hour greater than a threshold valve) and Minor repair having (repair hour less than (or)equal to threshold valve). This approach is mainly for Weibull distribution method. In Weibull analysis is a common method for failure analysis and reliability engineering used in a wide range of applications. In this paper, the applicability of Weibull analysis for evaluating and comparing the reliability of the schedule performance of multiple projects is presented, while the successive performance of multiple projects is presented, while the successive repair times are increasing and are exposing to Weibull distribution, under these assumptions, an optimal replacement policy ‘T’ in which we replace the system, when the repair time reaches T. It can be determined that an optimal repair replacement policy T* such that long run average cost and the corresponding optimal replacement policy T* can be determined analytically.

Improving Bridge Expansion and Contraction Installation Replacement Decision System Using Hybrid Chaotic Whale Optimization Algorithm

Bridge expansion and contraction installation (BECI) has proved to be an essential component of the bridge structure due to its stability, comfort, and durability benefits. At present, traditional replacement technologies for modular type, comb plate type, and seamless type BECIs are widely applied worldwide. Nevertheless, it is unfortunate that the research conducted on decision-making (DM) approaches for the technical condition assessment and the optimal replacement plan selection of existing BECIs remain scarce, which results in the waste of resources and the increase in cost. Therefore, a BECI technical condition assessment approach, which contains specific on-site inspection regulations with both qualitative and quantitative descriptions, is proposed in this research, and a corresponding calculation program has been developed based on the MATLAB platform, which provides the basis for the necessity of replacement. Simultaneously, the hybrid chaotic whale optimization algorithm is designed and performed to improve and automate the process of optimal replacement plan selection under the assistance of the analytic hierarchy process (AHP), where both the achievement in consistency modification and the reservation of initial information are perused, and its superiority and effectiveness are verified via the comparative experimental analysis. The improved BECI replacement decision system is established, and the corresponding case study demonstrates that the proposed system in this research proves reasonable and feasible. The improved system can effectively assist bridge managers in making more informed operation and maintenance (O and M) decisions in actual engineering projects.

Durability of Ternary Cements Based on New Supplementary Cementitious Materials from Industrial Waste

Cement-based materials decay with exposure to aggressive agents, a development that raises infrastructure operation and maintenance costs substantially. This paper analyses the inclusion of ultrafine construction and demolition (UC&DW) and biomass-fuelled power plant (BA) waste as pozzolanic additions to cement in pursuit of more sustainable and eco-respectful binders and assesses the durability of the end materials when exposed to seawater, chlorides (0.5 M NaCl) or sulphates (0.3 M Na2SO4). The effect of adding silica fume (SF) at a replacement ratio of 5% was also analysed. Durability was determined using the methodology proposed by Koch and Steinegger, whilst microstructural changes were monitored with mercury intrusion porosimetry (MIP), X-ray diffraction (XRD) and scanning electron microscopy (SEM) for a fuller understanding of decay processes. According to the findings, the new blended cements containing 20%UC&DW + 10%BA or 20%UC&DW + 20%BA + 5%SF resist the attack by the aggressive media studied, with a 56-d corrosion index of over 0.7. The composition of the reaction products generated with the attack is essentially the same in OPC and the SCM-bearing materials. The results show that the optimal replacement ratio for SCM is 30%.

Optimal Replacement, Retrofit, And Management Of A Fleet Of Assets Under Regulations Of An Emissions Trading System

This thesis presents the development of a model for parallel replacement and improvement for a fleet of assets to minimize both the economic costs and greenhouse gas (GHG) emissions where the emissions are limited by cap-and-trade. The firm which owns the assets has the options of using the assets, putting them in inventory, improving them, or salvaging them. Different technological types and their performances have been considered for assets. The firm has the option of purchasing new assets from varying technologies and/or improving its existing assets to a higher-performance type. Moreover, the model considers the possibility of both banking the emission allowances and trading them in the market. The model was later used with data of a fleet of excavators in Ontario, Canada. The use of this model could help emitter firms to simultaneously manage the emissions and costs of their fleet of assets in a jurisdiction regulated by cap-and-trade.

Optimal Replacement, Retrofit, And Management Of A Fleet Of Assets Under Regulations Of An Emissions Trading System

This thesis presents the development of a model for parallel replacement and improvement for a fleet of assets to minimize both the economic costs and greenhouse gas (GHG) emissions where the emissions are limited by cap-and-trade. The firm which owns the assets has the options of using the assets, putting them in inventory, improving them, or salvaging them. Different technological types and their performances have been considered for assets. The firm has the option of purchasing new assets from varying technologies and/or improving its existing assets to a higher-performance type. Moreover, the model considers the possibility of both banking the emission allowances and trading them in the market. The model was later used with data of a fleet of excavators in Ontario, Canada. The use of this model could help emitter firms to simultaneously manage the emissions and costs of their fleet of assets in a jurisdiction regulated by cap-and-trade.

Durability of Cement Paste with Metakaolin

Durability characteristics of cement paste with two types of metakaolin (MK1 and MK2) replacement were examined. "Fluidized bed" calcination produced MK1 which was relatively pure, while "flash" calcination produced MK2, which had a high amount of quartz mixed in. At a 50% replacement after 28 days, porosity increased by 8.9 and 7% for MK1 and MK2 while primary sorptivity decreased. Thermogravometric and XRD analysis showed a decrease in the portlandite content by 79 and 75% for MKI and MK2, while the CaCO3 level did not change significantly. MK2, at an optimal replacement range of 5-30% produced relatively more CSH than MK1. Observed by SEM, metakaolin particles in MK2 were consumed by the pozzolanic activity more thoroughly than the particles of quartz. Metakaolin replacement levels of 20% or more for MK1, and 25% or more for MK2, made the cement paste very susceptible to carbonation ingress. Hydration stopping with propan-2-ol appeared to cause cracking while freeze-drying worked with no apparent problems. M

Comparison of the replacement policy in k-out-of-n systems having dependent components

This paper is concerned with two optimization problems for a k-out-of- n system consisting of dependent components such as finding the number of elements in the system that minimize the system’s mean cost rate and the system’s optimal replacement time. In previous studies, either system consisting of independent components or parallel systems, a particular case of the present study, was examined. In particular, we numerically examine how the components’ dependence affects the optimal number of units and replacement time for the system, minimizing mean cost rates. We consider when the components are exchangeable and dependent, that is, the system consists of dependent components. For three vastly used Clayton, Gumbel, and FGM copula functions, comparative numerical results are presented.