Spatiotemporal Correlation Feature Spaces to Support Anomaly Detection in Water Distribution Networks

Monitoring disruptions to water distribution dynamics are essential to detect leakages, signal fraudlent and deviant consumptions, amongst other events of interest. State-of-the-art methods to detect anomalous behavior from flowarate and pressure signal show limited degrees of success as they generally neglect the simultaneously rich spatial and temporal content of signals produced by the multiple sensors placed at different locations of a water distribution network (WDN). This work shows that it is possible to (1) describe the dynamics of a WDN through spatiotemporal correlation analysis of pressure and volumetric flowrate sensors, and (2) analyze disruptions on the expected correlation to detect burst leakage dynamics and additional deviant phenomena. Results gathered from Portuguese WDNs reveal that the proposed shift from raw signal views into correlation-based views offers a simplistic and more robust means to handle the irregularity of consumption patterns and the heterogeneity of leakage profiles (both in terms of burst volume and location). We further show that the disruption caused by leakages can be detected shortly after the burst, highlighting the actionability of the proposed correlation-based principles for anomaly detection in heterogeneous and georeferenced time series. The computational approach is provided as an open-source tool available at GitHub.

Process Dynamic of Two-Thermal-Tank-Series with Dead Time

The multi-tank-series system could come up the problem of instability due to dead-time. The goals of this work are to study the dynamic behavior of Two-Thermal-Tanks-Series (TTTS) with dead time through the open loop experiment in laboratory, and to propose the new-module of fundamental chemical engineering practicum in field of process dynamic for undergraduate program. The two stirred-tank-heaters @10L were designed for heating of water fluid. Both of tanks were designed overflow to maintain their volume constant. The gate valve was installed in the inlet pipe of Tank-1 to adjust its volumetric flowrate (f). The inlet temperature of Tank-1 (T1), the liquid temperatures in Tank-1 (T2) and Tank-2 (T3) were measured by thermocouple multi-channels. The volt-ampere-regulators were used to adjust the electrical energy in Tank-1 (q1) and Tank-2 (q2). The mathematical model was solved and rigorously examined in Xcos/Scilab. In order to study the dynamic behavior of TTTS, the inlet flowrate disturbance was made based on step input change. According to our investigation in laboratory and open loop simulation, both Tank-1 and Tank-2 gave stable responses, the model’s responses showed the closed and similar trend with laboratory’s responses, and time delay of about 30 seconds has been found in Tank-2.

Radial spreading of turbulent bubble plumes

Weak bubble plumes carry liquid from the environment upwards and release it at multiple intermediate levels in the form of radial intrusive currents. In this study, laboratory experiments are performed to explore the spreading of turbulent axisymmetric bubble plumes in a liquid with linear density stratification. The thickness, volumetric flowrate and spreading rates of multiple radial intrusions of plume fluid were measured by tracking the movement of dye injected at the source of bubbles. The experimental results are compared with scaling predictions. Our findings suggest that the presence of multiple intrusions reduces their spreading rate, compared to that of a single intrusion. This work is of relevance to the spreading of methane plumes issuing from the seabed in the Arctic Ocean, above methane-hydrate deposits. The slower, multiple spreading favours the presence of methane-rich seawater close to the plume, which may reduce the dissolution of methane in the bubbles, and thus promote the direct transport of methane to the atmosphere. This article is part of the theme issue ‘Stokes at 200 (part 2)’.

One-Day Prognoses of Methane Concentrations for the 102 Longwall in the 325/1 Seam in the “W” Coal Mine Operating in a Continuous System

The first part of the paper concerns the natural deposition conditions of the 325/1 seam in the “W” coal mine, in the 102 longwall mining panel. It also presents the most important technical conditions regarding the exploitation at this longwall. To characterize the methane hazard in the longwall area, the parameters of ventilation and total methane concentrations as well as the volumetric flowrate of methane captured by the methane removal system, have been presented graphically. A significant part of the methane flow in the longwall area was released to the air flowing to the longwall. The most significant part of the article is the presentation and analysis of the results of prognoses of mean methane concentrations at the exhaust of the longwall area. The accuracy of the prognoses of methane concentration was verified using two methods: while not considering the release of methane to the air flowing to the longwall and while considering the total flowrate of methane to the ventilation air in the area of the 102 longwall. The method of forecast presented in the article has so far been checked for a 5-day and 6-day work day, as well as for walls operating in a non-regular mode. The article refers to the wall operating in a continuous mode, which required adaptation of the proposed method to this mode. The application of the one-day forecast proposed in the article allows for undertaking temporary methane prevention measures enabling safe use of the wall.

Hollow Fiber Ultrafiltration Membrane for Methyl Green Dye Removal

In this study, the behavior of a Polyvinyl chloride (18 wt % PVC) hollowfiber ultrafiltration (UF) membrane for methyl green (MG) dye removalfrom aqueous solution was estimated by studying the influence of varyingthe operation conditions (the concentration of the dye and volumetric flowrate) to determine their impact on the separation processes (permeate fluxand rejection coefficient) at constant pressure and temperature. The PVCmembrane was characterized by scanning electron microscopy.Furthermore, tests of the UF were carried out with pure water and MGaqueous solutions as feed. Outcomes explained a notable influence of feedconcentration and flow rate on the rejection and permeate flux, with thehighest rejection coefficient value close to 75.2% of the membrane system,at neutral pH.

Effect of Additional MnFe2O4 on a Combination of EG-Water Nanofluid and Volumetric Flowrate Variations towards Heat Transfer in Shell and Tube Heat Exchanger System

Nanofluid is an efficient fluid when used in heat exchanger system because of its larger thermal conductivity compared to conventional fluids such as water, oil, and ethylene glycol (EG). This research used MnFe2O4 nanoparticle due to its higher magnetic sensitivity compared to other ferrite nanoparticles and larger thermal conductivity than TiO2. This research used the MnFe2O4 nanoparticle with a combination of EG-Water base fluids in ratios of 40:60, 60:40, and 80:20. MnFe2O4 nanofluid mixed with EG-Water base fluids was made using the two-step method with 0.05% MnFe2O4 volume fraction in each base fluid ratio. This research used shell and tube type heat exchanger with heat temperature of 60°C and cold temperature of 26°C that were carried out at volumetric flowrate in each base fluid ratio for 0.22 l/m, 0.44 l/m, and 0.66 l/m. This research aimed to find the best combination ratio of EG-Water in thermophysical (thermal conductivity, specific heat, density, and viscosity) and to find the effect of volumetric flowrate variations on the heat exchange characteristics (the Reynold number, the Nusselt number, ∆T LMTD, convection coefficient, heat transfer, and overall heat transfer coefficient). The results of this research were that the sample of EG-Water with 40:60 ratio had the best heat transfer characteristics compared to samples with 60:40 and 80:20 ratios. Meanwhile, for the volumetric flow rate, a higher volumetric flow rate resulted in a larger result.

An Uncertainties Simulation Model Applied to an Automated Laminar Flowmeter

Aircraft oxygen regulators are a normally used specialized test bench designed to perform tests to the regulators during its work conditions. The tests are performed placing the regulator in the barometric chamber, where low pressure conditions are forced to simulate altitude conditions and then a flow is forced on the output of the regulator to simulate the inhalation of the user. The relevant test flows are measured by laminar flowmeters. These flowmeters are meant to measure the flowrate at pressures correspondent to altitudes between sea level altitude and fifty thousand feet. In this work a way was studied to automate laminar flowmeters used on oxygen regulator test benches. For this purpose, was developed a data acquisition system (DAS) using a microcontroller board and two microelectromechanical systems—MEMSs (a pressure and temperature sensor and a differential pressure sensor). Since these MEMSs did not have factory calibration, they were calibrated in this study. The automated flowmeter was also calibrated. To estimate the error of flow rate measured by this solution, an uncertainties simulation model based on the Monte Carlo method and several calibrations were performed. According to the automated flowmeter calibration, the uncertainty obtained (±0.45% fs) is accepted, but the authors only recommend its use for actual volumetric flowrate measurements.

Theoretical and Experimental Analysis of Waste Heat Recovery Effectiveness of a Diesel Engine

The study utilized the exhaust gas from a diesel engine to preheat water in the constructed shell and tube heat exchanger. The theoretical analysis of the heat exchanger was carried out using the Log Mean Temperature Difference (LMTD) method. The Volumetric flowrate of the water was manipulated using a valve and the resulting output temperature of water leaving the heat exchanger was recorded. Experimentation was carried out to determine the effects of volumetric flow rate on the output temperature and the effectiveness of the heat exchanger. After the test and data analysis, it was discovered that that at flow rate of 3.0 Liter per minute (LPM) the effectiveness of the heat exchanger was peak at 43.34%. The volumetric flow rate of water is inversely proportional to the output temperature of water and it was also established that the effectiveness of the heat exchanger depends on output temperature of and the mass flow rate of the water. Also it was proven that by preheating water before it enters the boiler of the Rankine cycle the efficiency of the cycle increases.

New solid particle seeding generator for laser-based velocity measurements in reacting flows

The design of a new solid particle seeding generator for laser-based velocity measurements in gaseous flows is reported. Performance tests revealed that the new seeder has the ability to control the concentration of seeding particles in a flow independently of the flowrate. It also can provide a steady supply of seeding particles, operate over an extended range of flowrate, and break up agglomerates into smaller particles. These features give this seeder advantages over its counterparts, especially at low volumetric flowrate.

Assessing the degree of plug flow in oxidation flow reactors (OFRs): a study on a Potential Aerosol Mass (PAM) reactor

Oxidation flow reactors (OFRs) have been developed to achieve high degrees of oxidant exposures over relatively short space times (defined as the ratio of reactor volume to the volumetric flowrate). While, due to their increased use, attention has been paid to their ability to replicate realistic tropospheric reactions by modeling the chemistry inside the reactor, there is a desire to customize flow patterns. This work demonstrates the importance of decoupling tracer signal of the reactor from that of the tubing when experimentally obtaining these flow patterns. We modeled the residence time distributions (RTDs) inside the Washington University Potential Aerosol Mass (WU-PAM) reactor, an OFR, for a simple set of configurations by applying the tank-in-series (TIS) model, a one parameter model, to a deconvolution algorithm. The value of the parameter, N, is close to unity for every case except one having the highest space time. Combined, the results suggest that volumetric flowrate affects mixing patterns more than use of our internals. We selected results from the simplest case, at 78 s space time with one inlet and one outlet, absent of baffles and spargers, and compared the experimental F-Curve to that of a computational fluid dynamics (CFD) simulation. The F-Curves, which represents the cumulative time spent in the reactor by flowing material, match reasonably well. We value that the use of a small aspect ratio reactor such as the WU-PAM reduces wall interactions, and suggest applying the methodology of tracer testing described in this work to investigate RTDs in OFRs and modify inlets, outlets, and use of internals prior to applications (e.g., field deployment vs. laboratory study).