Simulation Analysis of Thermal Mixing Characteristics of Fluids Flowing Through a Converging T-junction

Temperature fluctuation occurs while mixing of hot and cold fluids in a T-junction due to incomplete thermal mixing. This temperature fluctuation can produce thermal fatigue at the weld area of the T-junction. The present study aims to numerically investigate the thermal mixing characteristics of hot and cold fluids in a T-junction. The realizable k-ε turbulence model is used with natural gas as the working fluid. Temperature distribution, mixing quality, and intensity of temperature fluctuation are evaluated and compared along with the mixing outlet. The inlet temperature difference and branch to main pipe flowrate ratio have a direct influence on thermal mixing. The higher temperature difference can reduce the thermal mixing performance. Thermal mixing increases with the increase of branch to main pipe flowrate. The intensity of temperature fluctuation is found within a short distance from the intersecting point of the two inlets. With the increase of distance along with the mixing outlet, the frequency of temperature fluctuation decreases, and thermal mixing increases.

Adaptive Multi-state Pipe Framework Based on Set Pair Analysis

Human Activity Recognition (HAR) is one of the main research fields in pattern recognition. In recent years, machine learning and deep learning have played important roles in Artificial Intelligence (AI) fields, and are proven to be very successful in classification tasks of HAR. However, there are two drawbacks of the mainstream frameworks: 1) all inputs are processed with the same parameters, which would cause the framework to incorrectly assign an unrealistic label to the object; 2) these frameworks lack generality in different application scenarios. In this paper, an adaptive multi-state pipe framework based on Set Pair Analysis (SPA) is presented, where pipes are mainly divided into three kinds of types: main pipe, sub-pipe and fusion pipe. In the main pipe, the input of classification tasks is preprocessed by SPA to obtain the Membership Belief Matrix (MBM). The sub-pipe shunt processing is performed according to the membership belief. The results are merged through the fusion pipe in the end. To test the performance of the proposed framework, we attempt to find the best configuration set that yields the optimal performance and evaluate the effectiveness of the new approach on the popular benchmark dataset WISDM. Experimental results demonstrate that the proposed framework can get the good performance by achieving a result of 1.4% test error.

A Basic Experimental Study on Analysis of Leak Signal and Monitoring Method for Water Supply Pipe

Water supply systems are essential elements for human life and industry, and water leaks and water supply cut-off may cause major problems. Local water leaks and pipe failures in the water supply system are inevitable problems due to the aging of pipes. Therefore, leakage detection and prevention are required to monitor the integrity of the water supply system. This paper is a fundamental study on the applicability of the smart bolt, which was developed as a monitoring system to detect water leakage in water supply monitoring. Detection experiments were conducted using a smart bolt with a built-in strain sensor and an accelerometer. Through finite element analysis using ANSYS 2019 R2 and tensile strength testing, the strength of the smart bolt was confirmed to have the acceptable tensile strength. The smart bolt used in this study was verified to meet the allowable criteria of torque and tensile stress for a municipal water supply system. The frequency responses of the simulated leakage pipe system, according to the leakage of the valve and the main pipe, were analyzed, and a leak signal at the valve leak point was detected in the 60-Hz band. The main pipe leaking point was observed to produce a leak signal with a much higher-order mode than that of the valve leak point. Therefore, the smart bolt can be applied to detect warning leak signs from water supply valves and to monitor for loosening of the bolts.

Distribution Uniformity in Intensive Horticultural Systems of Almería and Influence of the Production System and Water Quality

The high productivity and efficiency of the use of irrigation water that characterizes greenhouse horticultural crops can be affected by poor irrigation distribution uniformity. The objective of this work was to estimate the average irrigation distribution uniformity (DU) of the greenhouses in Almería, determining the influence of the irrigation water quality as well as the production system on this uniformity. A prospective study was carried out in which commercial farms were selected that used different water qualities (groundwater vs. reclaimed) with different production systems (organic vs. conventional/integrated). The average irrigation distribution uniformity in the greenhouses of Almería was 80%. The farms with organic production systems presented a drastic DU reduction with respect to conventional farms (48% vs. 88%). The DU of the irrigation water presented in commercial farms irrigated with reclaimed water presented a lower DU than those irrigated with groundwater (76% vs. 86%). The distribution of irrigation depth of water in the greenhouses showed slight variations (from 3.2 to 2.9 mm) depending on the emitter position, with the highest values being at the head of the sub-main pipe and dripper line and the lowest at the end of the sub-main pipe and dripper line. The depth of water values was very close to the theoretical average of 3 mm. Water quality affects the distribution pattern of the depth of water in greenhouses. Installations irrigated with reclaimed water showed greater oscillation of the water depth within the sub-unit, varying from 3.6 to 2.0 mm, although the average depth was located close to the theoretical depth (3 mm). The production system affected the distribution of the depth of water—in the organic system, the depth underwent greater variation depending on the position of the emitter in the sub-unit, ranging from 1.7 to 3.3 mm. In addition, within this production system, the median depth of water was close to 2.5 mm, lower than the theoretical depth (3 mm), which denoted a certain generalized filling that was accentuated at the end of the dripper line and sub-main pipe.

Planning of the Clean Water Distribution System Pipeline at Griya Arwana Lestari Housing, Merauke Regency

Griya Arwana Lestari Housing Merauke Regency is one of the housing estates located in the area around the Merauke coast. The majority of residents of Griya Arwana Lestari housing use rainwater sources and buy water from water tanker trucks for their clean water needs. When the dry season arrives, the price of water from tanker trucks is quite expensive, making it difficult for residents of Griya Arwana Lestari housing to get clean water. So it is necessary to plan a clean water supply network system. The purpose of this study is to find out how much the discharge needs of clean water in Griya Arwana Lestari housing and find out what the diameter of the main pipe and secondary pipe are used. The method used is qualitative and quantitative based on field observations and counting the number of occupants in sustainable arowana housing then analyzing the need for clean water and then determining the diameter of the main pipe and secondary pipe. The results in this study are the required discharge in the housing is 3,973 l/s and for the main pipe diameter is 4 inches and for the secondary pipe 1 inch.

Anti-resonance frequency control by span-tuning dynamic vibration absorber for brush cutter vibration reduction

Significant handle vibrations often occur during mowing operation even with anti-vibration type brush cutters. This is caused by combined-bending natural mode of the main pipe and driveshaft which is mainly excited by cutting head rotational force. In this study, we focused on the placement span of the rubber bushings that support the driveshaft to suppress this kind of resonance. More specifically, we have designed a new component, called a span-tuning dynamic vibration absorber (ST-DVA), which utilizes the bending mode of the driveshaft that is determined by the placement span of rubber bushings. Analysis results of the finite element method (FEM) showed that the ST-DVA generated anti-resonance at a specific point on the main pipe under the first-order inertial force of the cutting head. We also succeeded in controlling anti-resonance frequency under the excitation. In actual measurements at the target frequency, handle vibration of the first-order component of the cutting head could be reduced by 51% and overall handle vibration could be reduced by 49% compared with those produced via equal-span rubber bushing placement. Hence, our study provides a design method that makes it possible to utilize the driveshaft, which a primary brush cutter component, as a dynamic vibration absorber by altering the placement span of the rubber bushings.

Master and Auxiliary Compound Control for Multi-Channel Confluent Water Supply Switching Control Based on Variable Universe Fuzzy PID

During the multi-channel confluent water supply process, the pressure control of the main pipe is often held back by such problems as non-linearity, hysteresis and parameter uncertainty, its own unique load dynamic changes, channel switching disturbance and other system characteristics caused by the actual working conditions. Moreover, pressure fluctuations in the main pipe will lead to a reduction in the service life of fire-fighting equipment, an increase in the failure rate, and even an interruption of the fire-fighting water supply. Therefore, a master and auxiliary control strategy is proposed to stabilize the pressure change in the process of multi-channel concentrated water supply switching, by using variable universe fuzzy proportional integral derivative (PID) control as the main controller on the main pipe and traditional PID control as the subsidiary controller on the channel. The control strategy is verified by the co-simulation platforms of LabVIEW and AMESim. Simulation results show that the variable universe fuzzy PID control and the master and auxiliary compound control based on the variable universe fuzzy PID control have advantages in step response, tracking response and anti-interference, respectively. The parameters obtained in the co-simulation are used in the experimental system. The experimental results show that the maximum deviation rate of main pipe pressure can be reduced by about 10% compared with other control methods under different loads. In conclusion, the proposed control strategy has strong anti-interference ability, fast dynamic response speed, high stability and good peak shaving effect.

A Comparative Study on the Calculating of Thickness and Height at T-Shaped Branch for KS D 3595 Stainless Steel Pipe using the Results both the Finite Element Method and the Experiment

Stainless steel pipe for general piping specified under the KS D 3595 standard is used as a substitute for carbon steel pipe in places where corrosion of coastal regions is a concern because there is little risk of corrosion. In order to install the branch pipe from the main pipe, the pipe is punched into the elliptical shape and the cone-shaped plug is pulled out of the main pipe to form a T-Shaped branch portion. However, there is a problem that is damaged when welding the pipe to the branch, but it is insufficient to understand the behavior of the material and the principle of damage due to plastic deformation when forming the branch. Hence, in this study, material behavior and stress were analyzed through finite element analysis. The diameter of the KS D 3595 stainless steel main was varied from 75 mm to 100 mm and the diameter of the branch pipe was varied from 25 mm to 80 mm. So, a total of eighteen cases were analyzed. The obtained results indicate that the maximum residual stress occurs in the central portion of the pipe along the longitudinal direction of the branch, and the residual stress increases as the size of the branch processing portion increases. Furthermore, in this study the minimum cutting height required for compatibility with the minimum thickness of the branching portion is reported.