scholarly journals Water Pipe Replacement Scheduling Based on Life Cycle Cost Assessment and Optimization Algorithm

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 605
Author(s):  
Fatemeh Ghobadi ◽  
Gimoon Jeong ◽  
Doosun Kang
Keyword(s):  
Life Cycle ◽  
Urban Communities ◽  
Life Cycle Cost ◽  
Water Distribution ◽  
Large Scale ◽  
Distribution Networks ◽  
Water Pipe ◽  
Annual Budget ◽  
Pipe Replacement ◽  
Scheduling Plan

Water distribution networks (WDNs) comprise a complex network of pipes and are crucial for providing potable water to urban communities. Therefore, WDNs must be carefully managed to avoid problems such as water contamination and service failures; however, this requires a large budget. Because WDN components have different statuses depending on their installation year, location, transmission pressure, and flow rate, it is difficult to plan the rehabilitation schedule within budgetary constraints. This study, therefore, proposes a new pipe replacement scheduling approach to smooth the investment time series based on a life cycle cost (LCC) assessment for a large-scale WDN. The proposed scheduling plan simultaneously considers both the annual budget limitation and the optimum expenditure on the useful life of pipes. A multi-objective optimization problem consisting of three decision-making objectives—minimum imposed LCC on the network, minimum standard deviation of annual investment, and minimum average age of the network—is thus solved using a nondominated sorting genetic algorithm to obtain an optimal plan. Three scenarios with different pipe replacement time spans and different annual budget constraints are considered accordingly. The results indicate that the proposed scheduling framework provides an efficient water pipe replacement scheduling plan with a smooth management budget.

scholarly journals Performance-based multi-objective design and expansion of water distribution networks considering life cycle costs and future demands

2021 ◽  
Author(s):  
Swati Sirsant ◽  
M. Janga Reddy
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Water Distribution ◽  
Structural Integrity ◽  
Population Change ◽  
Capacity Expansion ◽  
Distribution Networks ◽  
Water Distribution Networks ◽  
Pareto Optimal ◽  
Multi Objective

Abstract Designing the Water Distribution Networks (WDNs) consists of finding out pipe sizes such that the demands are satisfied and the desired performance levels are achieved at minimum cost. However, WDNs are subject to many future changes such as an increase (or decrease) in demand due to population change and migration, changes in water availability due to seasonal and climatic change, etc. Thus, the capacity expansion of WDNs needs to be performed such that the cost of interventions made is minimum while satisfying the demand and performance requirements at various time periods. Therefore, the current study proposed a Dynamic Programming (DP) framework for capacity expansion of WDNs and solved using Multi-Objective Self Adaptive Differential Evolution (MOSADE). The methodology is tested on three benchmark WDNs, namely Two-loop (TL), GoYang, and Blacksburg (BLA) WDNs, and applied to a real case study of the Badlapur region Maharashtra, India. The results show that the proposed methodology leads to effective Pareto optimal fronts, making it an efficient method for solving WDN expansion problems. Subsequently, an Analytical Hierarchy Process (AHP) based multi-criteria decision-making (MCDM) analysis was performed on the obtained Pareto-optimal solutions to determine the most suitable solution based on three criteria: Life Cycle Cost (LCC) of expansions, hydraulic reliability, and mechanical reliability. The main advantage of the proposed methodology is its capability to consider hydraulic performance as well as structural integrity and demand satisfaction in the face of hydraulic and mechanical failures.

scholarly journals Comparative Analysis of the Life-Cycle Cost of Robot Substitution: A Case of Automobile Welding Production in China

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 226
Author(s):  
Xuyang Zhao ◽  
Cisheng Wu ◽  
Duanyong Liu
Keyword(s):  
Life Cycle ◽  
Systems Engineering ◽  
Life Cycle Cost ◽  
Manufacturing Systems ◽  
Large Scale ◽  
Cost Allocation ◽  
Industrial Robot ◽  
Case Analysis ◽  
Industrial Robots ◽  
Analysis Model

Within the context of the large-scale application of industrial robots, methods of analyzing the life-cycle cost (LCC) of industrial robot production have shown considerable developments, but there remains a lack of methods that allow for the examination of robot substitution. Taking inspiration from the symmetry philosophy in manufacturing systems engineering, this article further establishes a comparative LCC analysis model to compare the LCC of the industrial robot production with traditional production at the same time. This model introduces intangible costs (covering idle loss, efficiency loss and defect loss) to supplement the actual costs and comprehensively uses various methods for cost allocation and variable estimation to conduct total cost and the cost efficiency analysis, together with hierarchical decomposition and dynamic comparison. To demonstrate the model, an investigation of a Chinese automobile manufacturer is provided to compare the LCC of welding robot production with that of manual welding production; methods of case analysis and simulation are combined, and a thorough comparison is done with related existing works to show the validity of this framework. In accordance with this study, a simple template is developed to support the decision-making analysis of the application and cost management of industrial robots. In addition, the case analysis and simulations can provide references for enterprises in emerging markets in relation to robot substitution.

The Role of Cost Breakdown Structure in Life Cycle Cost Model

2015 ◽  
Vol 74 (2) ◽  
Author(s):  
Ooi Chu Hui ◽  
Abdul Hakim Mohammed
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Water Distribution ◽  
Single Phase ◽  
Cost Model ◽  
Pipeline Networks ◽  
Useful Life ◽  
Cost Breakdown Structure ◽  
Cost Breakdown

This paper highlights the basic process of developing a life cycle cost model and the role of cost breakdown structure for water distribution pipeline networks. A life cycle cost is the total cost of owning an asset during its predicted useful life, while a cost breakdown structure illustrates all the costs emerged in each single phase of the asset’s life cycle cost. Its purpose is to identify, define and organize all cost elements to be taken into account in a life cycle cost. Each cost element included in developing a cost breakdown structure will also be discussed in this paper.

scholarly journals Pipe replacement by age only, how misleading could it be?

2018 ◽  
Vol 19 (3) ◽  
pp. 846-854 ◽  
Author(s):  
M. A. Pardo ◽  
J. Valdes-Abellan
Keyword(s):  
Water Distribution ◽  
Energy Savings ◽  
Distribution Networks ◽  
Water Distribution Networks ◽  
Water Utility ◽  
Efficient Management ◽  
Utility Companies ◽  
Pipe Replacement ◽  
Energy Audits ◽  
The Impact

Abstract Traditional methods for prioritizing the renewal of water are based on heuristic models, such as the number of breaks per length, rule-of-thumb, and records held by the water utility companies. Efficient management of water distribution networks involves factoring in water and energy losses as the key criteria for planning pipe renewal. Prioritizing the replacement of a pipe according to the highest value of unit headloss due to ageing does not consider the impact on water and energy consumption for the whole network. Thus, this paper proposes a methodology to prioritize pipe replacement according to water and energy savings per monetary unit invested – economic prioritization. This renewal plan shows different results if comparing with replacing pipelines with regard to age and it requires calculating water and energy audits of the water distribution networks. Moreover, the required time to recover the investment performed needs to be calculated. The methodology proposed in this work is compared with the unit headloss criterion used in a real water-pressurized network. The results demonstrate that using the unit headloss criterion neither water, energy nor the investment is optimized. Significant water and energy savings are not fully exploited.

scholarly journals An Inverse Transient-Based Optimization Approach to Fault Examination in Water Distribution Networks

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1154
Author(s):  
Chao-Chih Lin ◽  
Hund-Der Yeh
Keyword(s):  
Water Distribution ◽  
Large Scale ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Small Scale ◽  
Optimization Approach ◽  
Promising Technique ◽  
Preliminary Screening ◽  
Detection Approach ◽  
Symbiotic Organism Search

This research introduces an inverse transient-based optimization approach to automatically detect potential faults, such as leaks, partial blockages, and distributed deteriorations, within pipelines or a water distribution network (WDN). The optimization approach is named the Pipeline Examination Ordinal Symbiotic Organism Search (PEOS). A modified steady hydraulic model considering the effects of pipe aging within a system is used to determine the steady nodal heads and piping flow rates. After applying a transient excitation, the transient behaviors in the system are analyzed using the method of characteristics (MOC). A preliminary screening mechanism is adopted to sift the initial organisms (solutions) to perform better to reduce most of the unnecessary calculations caused by incorrect solutions within the PEOS framework. Further, a symbiotic organism search (SOS) imitates symbiotic relationship strategies to move organisms toward the current optimal organism and eliminate the worst ones. Two experiments on leak and blockage detection in a single pipeline that have been presented in the literature were used to verify the applicability of the proposed approach. Two hypothetical WDNs, including a small-scale and large-scale system, were considered to validate the efficiency, accuracy, and robustness of the proposed approach. The simulation results indicated that the proposed approach obtained more reliable and efficient optimal results than other algorithms did. We believe the proposed fault detection approach is a promising technique in detecting faults in field applications.

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