In this paper different methods for analysis of pipes breakage in urban water distribution networks are investigated. At first, it is necessary to obtain complete and exact information about the failures in the networks. Thus, a suitable form was designed for gathering the required information including all the necessary parameters for the analysis. Then the rates of annual pipe failures were assessed based on the diameter, age and availability of pipes. Mechanical reliability (availability) of network components is the probability that component is performing well in the networks during its lifetime. The results show that the rate of breakage is decreased by increasing the diameter in all pipe types (e.g. Steel, Asbestos Cement). Assessing the availability of the pipes according to their diameter and length reveals an increase in availability by increasing the diameter but a decrease in availability by increasing the length of the pipes. It is also seen that the rate of water loss decreases by increasing the diameter of pipes. Furthermore, an increase in the rate of failures is observed when pipes are aging. The results of pipe breakage analyzed. Introduced in this paper provide helpful information to be used in design, operation and rehabilitation of pipe networks.

The use of pumps linked in parallel or series in large scale pipe systems is usually inevitable, to meet the required head and discharge. Transient flow occurs following a pump failure in a pump group as a result of variations in the flow rate. This research is an investigation about waterhammer caused by one or more pump-switch off in a pump group when they are connected in parallel. The operation of each pump in the group during steady and unsteady state is analyzed. For this purpose, the fluid flow equations as well as the pumps relations including rotational speed change and head loss are combined and simultaneously solved in the time domain by the method of characteristic. From the results one can quantitatively conceive that the intermittent shut-down compared to suddenly switching off the whole pump group produces much less waterhammer pressures. Furthermore in the intermittent shut-down with different pump characteristics, it is suggested to firstly switch off the most powerful pump, and then the rest which are weaker. Appropriate interpretation about the transition results have been included.

AbstractIntroduction: It is essential to optimize repair, reconstruction and rehabilitation programs of urban water distribution networks for the correct use of limited water resources. The aim of the present study is to implement and compare two artificial intelligence methods to predict the burst rate of water pipes.Methods: In this article, dataset of the pipe bursts in Joopar water network from 2012 to 2017 has been collected. The parameters for predicting of pipe failure includes: material, age, diameter, water pressure and installation depth, and the correlation coefficient of these parameters with the failure rate has been investigated. In order to predict the failure rate, convolution neural network with support vector machine (RCNN-SVR) and fuzzy regression based on c mean clustering (FCMR) have been used. To compare the performance of these two methods, the criteria such as Root-Mean Squared Error (RMSE), Index Of Agreement (IOA), Mean Absolute Percentage Error (MAPE), and coefficient of determination (R2) have been used.Findings: According to the evaluations, RCNN-SVR method compared to FCMR method shows excellent results. Also, the correlation between age and failure rate in asbestos pipes is high and in polyethylene pipes this value is positive but low. The correlation coefficient between pressure and failure rate is also positive for both pipe types.

Introduction The concept of resilience is particularly important in water distribution networks, which are important urban infrastructures. Estimating and evaluating resilience in each network at the time of designing will reduce damage to subscribers and the network. In this research, relationships and functions related to resilience (GRA) in water supply systems and solutions for how to increase resilience using two scenarios of pipe failure and additional needs for the Kangavar network were investigated and implemented. Material and Method By modeling the initial failure modes by increasing the stress intensity and estimating the consequences that arise, the resilience of a system can be evaluated, which includes the following steps (Diao et al., 2016): Step 1. Identify the failure mode to evaluate (eg structural failure, excessive demand). Step 2. Determining the system stress associated with the failure mode and its simulation method (for example, WDS simulation with an additional load on a node for a certain period). Step 3. Identify the appropriate system and how to measure it (eg ratio of unsatisfied demand to total required demand during the failure period). Step 4: Simulating the consequences of the failure mode at increasing stress intensity (0%-100% of maximum stress). While stress intensities up to 100% may be highly undesirable, they are theoretically possible and should be considered if a wide range of potential effects are identified. For each given stress value, the appropriate number of failure scenarios is determined. Step 5. Creating a stress-resilience curve that shows the average, maximum, and minimum results produced by the simulation for each given stress value. Results The worst situation for Kangavar network starts at 89% failure and remains until 100% pipe failure. In large networks like the Kangavar network, the graph of the strain duration and the stress duration have a steep slope just like the supply shortage graph. For example, for the value of five percent pipe failure, all three values of minimum, average and maximum strain duration are equal to five. That is, when only five percent of Kangavar's pipes fail, the duration of the strain reaches its maximum. Among the prevention ways to reduce the lack of supply in case of pipe failure, adding parallel pipes for pipes with a more important position, compared to other pipes or looping the network in different areas of the network. For the Kangavar network, 38 pipes were added to the network. These pipes were mostly parallel to the pipes coming out of the tank. After adding only 38 pipes to the network, the amount of supply shortfall was greatly reduced. The state of excess demand is actually a state in which a number of certain nodes have a need or demand more than their defined capacity in a certain period of time. This situation is actually very similar to when a fire occurs in the network, except that in the case of a fire, the normal and usual demand of the network may decrease a little. But in this simulation, in addition to the normal need and demand, additional needs are also considered. Figure 12 shows the duration of the fire for hours 18 to 21. In this period of time, in the worst case, i.e. in 100% of the nodes with higher demand, the network faces only 10.82% supply shortage. This means that if all eleven selected points in the network have additional needs at the same time, the network will have an approximately 11% supply shortage. In this situation, it can be seen that the stress applied to the network occurs at the same moment and the duration of the strain is six hours. Conclusions The results showed that the duration of the strain increased with the increase in the percentage of pipe failure. But the graph related to the start of strain had a downward trend and approached zero with the increase in the percentage of pipe failure. The level of resilience for a network is different in different scenarios, in fact it is possible in with equal failure percentage, and the network has more resilience in one scenario than in another scenario. With a slight increase in the percentage of pipe failure in some water supply networks, the amount of strain increases greatly. While in other networks, even with a large increase in failure percentage, the size of the slope strain has started to increase slightly. One of the most important reasons for this depends on the type of network design. For example, if the water supply network is defined as a loop, in case of failure of one of the pipes, part of the lack of demand will be supplied by other pipes. Adding new pipes to the network was one of the solutions considered to increase the resilience of the network in this research.

The behavior of the buried pipes under the fault displacement is a complex issue. In the past earthquakes, fault displacement of 2.1, 3 and 4 meters have been reported. A review on the literature shows that understanding failure modes of buried pipelines under big fault displacement is considered as a challenge. In this paper, the objective is to investigate the influence of the thickness parameters of the pipe on pipe behavior at pipe intersection and fault. The behavior of the pipe is studied focusing on fault displacements greater than 1 meter. Using finite element ABAQUS software, the simulation was performed through dynamic analysis regarding to pipe-soil interaction. Pipe and soil Dimensions and material properties of the soil and pipe are fixed in all analyzed samples and, the fault displacement (0.2 to 3 meters) and the pipe thickness (from 8.2 to 20 mm) are variable parameters of this article. An analysis has been conducted for the two variables (fault displacement and the thickness of the pipe). Maximum axial strain values and pipe deformation modes under fault displacement are discussed. Likewise, the influence of pipe thickness and the amount of fault displacement on the value of strain of the pipe wall is indicated in numerical analysis in the result. In the displacement of less than 1 meter, the pipes are like the letter S and local buckling occurs in the pipeline. In the displacement of 1.5 meters and more, they are like the letter Z, and pipe deformation and wrinkling occur in the pipeline. In the displacement of more than 1.5 meters, distortion, and wrinkling pipe is deformed. In the displacement of more than 1 m, the strain decreases with increasing pipe thickness. Through the change of the pipe thickness, the pipe failure mode changes.

The diffusion process in the production of sugar is a determining process which affects the final quality of sugar. The pH of water which is used in this process is being controlled by adding sulphur dioxide gas to the water. In this research, the reason of corrosion of the sulphur dioxide gas transporter pipe to the diffusion water producer tank has been studied. In this way, the quantometery analysis of the base metal and weld zone, and X-ray diffraction analysis of the corrosion products has been applied. In addition, the corrosion rate of the base metal has been determined by the potentiodynamic polarisation technique at the temperatures between 50 t 70oC and also the DLEPR method has been used for the weld zone. The Results showed that the main reason of the corrosion of the pipe was the accumulation of the gas in the bottom of the pipe and the concentrated sulphur containing droplets which led to the localised corrosion of the pipe. Finally, changing the position of the branch pipes, shelving the pipe and changing the material are being suggested.

Introduction: The aim of this study is evaluation of efficacy of lacrimal sac localization with lacrimal probe without using light pipe. The study was based on nonrandomized prospective clinical trial with one year follow up period.Methods: A group of 40 patients operated since march 2001 to December 2004 The operation was Endoscopic Dacryocystorhynostomy and localization of lacrimal sac, which was performed with a lacrimal probe inserted in lacrimal sac. With pushing the probe inferomedialy pierces lacrimal sac lacrimal bone, and nasal musca over the bone. Follow up includes symptom evaluation such as epiphora and endoscopy. Success was defined as relief of symptoms & duct patancy with irrigation for a 1 year period.Results: 29 patients were male (72.5 %) and 11 were female (27.5 %). Mean age was 37.5 (with SD±12.26) in 20 patients right eye involved, left eye involved in 16 cases and in 4 cases both eyes involved. For 3 patients septoplasty was done besides EDCR. success rate was 82.5% and no complication was seen.Discussion: the use of lacrimal probe for lacrimal sac localization is a safe and easy method and don't have light pipe limitations then can replace light pipe.

In water supply systems, the accidents occurring in pipes are of the utmost importance and sensitivity. Failure of the pipes is not necessary with the end of their life and different factors namely age, diameter, material, stability and corrosion of soil and water, execution, installation and operational conditions such as hydraulic pressure are effective on it. At the same time studies show non comprehensiveness of presented relations in prediction of pipes failure rate. In this research, with regards to the available software and hardware, a structure was developed using combination of new optimization and simulation models. In this structure, theartificial neural networks were used for simulation of the pipes failure rate. Considering the point that neural networks are always consider as a black box and unable to provide the effect of each independent variable on the dependent variable, on the other hand, they are prone to incorrect training. Therefore, in this study to determine the input parameters affecting failure rate and the most appropriate structure of artificial neural network (as well as bios vectors, layers adjusting weights and the number of neurons), Genetic algorithm has been used with the aim of presentation of a structure which has the minimum error rate of simulation. In this algorithm, decision variables and properties of neural networks are the parameters affecting the failure rate. By running the developed optimization model, in addition to the effective parameters on pipe failure, the best neural network structure for simulation pipe failure rate can be determined. The advantage of the proposed method is full coordination between the input parameters and network structure in prediction of the pipes failure rate. The results of this study can be used to find the most appropriate relationship failure rate pipes with regards to the effective parameters and take necessary actions for decision making lead to resolve problems due to it. The results of this research indicating that the proposed combination method is able to extract the optimal and effective parameters on the pipes failure rate amongst the factors affecting failure rate, and also have been caused improve power capabilities and expansion of neural network structure that indicate high efficiency of the proposed method in simulation of nonlinear and complex relations.