Failure Rate Prediction Models of Water Distribution Networks

The economic, social and environmental impacts of water main failures impose a great pressure on utility managers and municipalities to develop reliable rehabilitation/replacement plans. The Canadian Infrastructure Report Card 2012 stated that 15.4% of Canadian water distribution systems was in a “fair” to “very poor” condition with a replacement cost of CAD 25.9 billion. The “fair”, “poor” and “very poor” conditions represent the beginning of deterioration, nearing the end of useful life and no residual life expectancy, respectively. The majority of municipalities in Canada do not possess complete dataset of water distribution networks. The annual number of breaks or breakage rate of each pipe segment is known as one of the most important criteria in condition assessment of water pipelines. The main objective of this research is to develop a research framework that circumvent the limitations of existing studies by: 1) identifying the most critical factors affecting water pipe failure rates, 2) determining the best mathematical expression for predicting water pipeline failure rate 3) developing deterioration curves, and 4) deploying sensitivity analysis to recognize the effect of each input change on the breakage rate. The proposed research framework utilizes Best Subset regression to recognize the most effective factors on water pipelines. Best-Subset Algorithm is a procedure to find the best combination of variables to predict the water pipe failure rate among all possible candidates. Once the process of critical factor selection is performed, selected variables are employed to predict the number of breaks of water pipes using Evolutionary Polynomial Regression (EPR). The EPR is an intuitive data mining technique performed in two stages: 1) the search for the best model using Multi-Objective Genetic Algorithm (MOGA), and 2) the parameter estimation for the model using Least Square Method. The predicted number of breaks, computed by EPR, is utilized to develop deterioration curves by applying Weibull distribution function. Finally, sensitivity analysis is performed to: 1) recognize the effect of changing each input on the failure rate, and 2) study the relationship between the selected inputs and the output. The developed research framework is applied into two case studies to test its effectiveness. The case considers the water distribution networks in the City of Montréal, Canada and the City of Doha, Qatar. Physical factors, such as age, length, diameter and pipe material were identified as the most critical factors to affect the failure rate of pipes. The results indicate that the developed models successfully estimated the number of breaks for the City of Montreal and City of Doha with a maximum R-Squared of 89.35% and 96.27%, respectively. Also, it is tested by using 20% of each dataset and promising results were generated with a maximum R-Squared of 84.86% and 74.39% for dataset of Montreal and Doha respectively. This demonstrates the accuracy and robustness of the developed models in assessing and analyzing water distribution networks. The developed model is useful for municipalities and decision makers to prioritize the maintenance, repair, rehabilitation, and budget allocation of water distribution networks

Developing the Performance of Sewage Pipelines Repairing Using Trenchless Methods (Case Study: Isfahan)

Nowadays, the using modern trenchless methods for repairing sewer networks have been developed in most countries. Generally, for repairing the sewage lines using trenchless methods, bypassing the repair zone is necessary. For this purpose, the damaged tube is blocked upstream of the damaged pipe using plugs and packers, and to prevent rejection, the sewage is pumped to the downstream pipes. However, the pumping of sewage is a very costly task. In this study, an effective method named “minimum pumping” (MP) is suggested using the capacity of the upstream pipes and manholes. In the proposed method, the timing needed to repair the damaged tube can be managed in a way that the cost of pumping is reduced. Here, as a case study, sewage pipes in Nazar Boulevard and Mirzakochek Khan Boulevard in Isfahan City in Iran have been repaired using the proposed method and the results are presented and analyzed. The results indicated that the proposed method is an effective method for reducing the cost of repairing in sewage networks. Using the proposed method, the pumping rate and, consequently its costs, were reduced from 35% to 50% for Nazar Boulevard sewer network and from 70% to 85% for Mirzakochek Khan Boulevard

Prediction of Breaks in Municipal Drinking Water Linear Assets

Improper asset management practices increase the probability of water main failures due to inactive intervention actions. The annual number of breaks of each pipe segment is known as one of the most important criteria for the condition assessment of water pipelines. This metric is also considered one of the major performance measures in levels of service (LoS) studies. In an effort to maximize the benefits of historical data, this research utilized the evolutionary polynomial regression (EPR) method in determining the best mathematical expression for predicting water pipeline failures. The prediction model was trained and tested on the city of Montreal water network. After determining the best independent variables through the best subset regression, pipelines were clustered based on their attributes (length, diameter, age, and material). The majority of the models provided high R2 values, but the highest performing model's R2 was 89.35%. Further, a sensitivity analysis was also performed and showed that the most sensitive parameter was the diameter, and the most sensitive material type to age was ferrous material. The tools and stages performed in this research showed promising results in predicting the expected water main failures using four different asset attributes. Therefore, this research can be implemented in asset management best practices and in LoS performance measures to predict the number of water pipeline failures. To further improve the prediction model, additional explanatory variables could be considered along with leveraging multiple artificial intelligence tools. 2020 American Society of Civil Engineers.Scopu

Immobilized Ag NPs on chitosan-biguanidine coated magnetic nanoparticles for synthesis of propargylamines and treatment of human lung cancer

The magnetically isolable nanobiocomposites have significant impact as the modified new generation catalysts in recent days. This has persuaded us to design and synthesis of a novel Ag NPs decorated biguanidine-chitosan (Bigua-CS) dual biomolecular functionalized core-shell type magnetic nanocomposite (Ag/Bigua-CS@Fe3O4). Bigua-CS could be introducing polysaccharide materials as potential coating agent to immobilizing and stabilizing metal nanoparticles. The material was characterized using several advanced techniques like fourier transformed infrared spectroscopy (FT-IR), inductively coupled plasma (ICP), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), atomic mapping, high resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometer (VSM) and X-ray diffraction (XRD). Towards the chemical applications of the material, we headed the multicomponent synthesis of diverse propargylamines by A(3) coupling in water, which ended up with excellent yields. Due to strong paramagnetism, the catalyst was easily isolable and reused in 9cycles without any leaching and considerable change in reactivity. In addition, the catalyst was engaged in biological assays like study of anti-oxidant properties by DPPH mediated free radical scavenging test using BHT as a reference molecule. Thereafter, on having a significant IC50 value in radical scavenging assay, we extended the bio-application of the catalyst in anticancer study of adenocarcinoma cells of human lungs. The three different cancer cell lines, PC-14, LC-2/ad and HLC-1 were used in this regard. The best result was achieved in the case of PC-14 cell line with strong IC50 values