Leak detection using instantaneous frequency analysis

Leaking pipes are a primary concern for water utilities around the globe as they compose a major portion of losses. Contemporary interest surrounding leaks is well documented and there is a proliferation of leak detection techniques. Although the reasons for these leaks are well known, some of the current methods for leak detection and location are either complicated, inaccurate and most of them are time consuming. Transient analyses offer a plausible route towards leak detection due to their robustness and simplicity. These approaches use the change of pressure response of the fluid in a pipeline to identify features. The method used in the current study employ a single pressure transducer to obtain the time domain signal of the pressure transient response caused by a sudden opening and closing of a solenoid valve. The device used is fitted onto a standard UK hydrant and both cause a pressure wave and acquire the pressure history. The work described here shows that the analysis using Hilbert transform (HT), Hilbert Huang transform (HIHT) and EMD based method is a promising tool for leak detection and location in the pipeline network. In the first part of the work, the analysis of instantaneous characteristics of transient pressure signal has been calculated using HT and HHT for both simulated and experimental data. These instantaneous properties of the signals are shown to be capable of detecting the reflection from the features of the pipe such as leakages and outlet. When tested with leak different locations, the processed results still show the existing of the features in the system. In the second part of the work, the study is based on newly method of analysing nonstationary data called empirical mode decomposition (EMD) for instantaneous frequency calculation for leak detection. First, the pressure signals were filtered in order to remove the noise using EMD. Then the instantaneous frequency was calculated and compared using different methods. With this method, it is possible to identify the leaks and also the features in the pipeline network. These were tested at different locations of a real water distribution system in the Yorkshire Water region

Kenaf Fiber Composite in Automotive Industry: An Overview

Recently, natural fibers become an attractive to automotive industry as an alternative reinforcement for glass fiber reinforced thermoplastics. Additionally, natural fiber components in the automotive industry can provide numerous advantages compared to synthetic conventional such as reduction of weight and cost,  recyclability, renewability and in addition to eco-efficiency. Thus, the use of natural fibers in automotive industry has shown increasingly stringent environmental criteria. Furthermore, amongst grouped bast fibers such as flax, hemp, jute, ramie and kenaf; kenaf fiber seen as potential natural fiber with robust mechanical properties. Kenaf fiber had been explored to enhance desired mechanical properties as an automotive structural components. As usual, natural fibres have some issues and disadvantages when used as reinforcements for polymeric composites. Therefore, some modification performed on fibers such as chemical treatment was carried out. In addition, the use of a coupling agent and a plasticizer can also increase fiber-matrix adhesive bonding

Irregularity detection in artificial signal using time-frequency analysis

A typical time signal contain overwhelming amounts of data and some of the signal components represent for irregularity such as crack and leak which greatly important to be identified precisely instead of using traditional method. The strategy can be done using signal processing method through high-quality time-frequency representation (TFR) for analysing such time dependent signals to accurately discover these superposition signal components. A few popular TFR methods such as wavelet transform analysis and relatively new, synchrosqueezed wavelet transform were applied in current study using artificial signal. From the result, both methods successfully discover an irregularity in the signal with different degree of accuracy and it is shown that synchrosqueezed wavelet transform provide the best and detailed time-frequency representation

Position Tracking Performance for ElectroHydraulic Actuator System with the Presence of Actuator Internal Leakage

Electro-hydraulic actuator (EHA) system is known as one of the highly nonlinear systems due to its parameters uncertainties. Many types of robust controller had been studied and proposed to control the nonlinear EHA system. Different parameters uncertainties test is needed in the procedure to evaluate the controller robustness. In this paper, the effect of the actuator internal leakage to the output actuator displacement is studied. The actuator output displacement is analyzed using Root Mean Square Error (RMSE) by means of giving sinusoidal input reference. The results show that as the actuator internal leakage increases, the RMSE will increase and the actuator will start to vibrate or show damping characteristics

Thermal stability and compression strength of rigid polyurethane/kenaf fibre biocomposite foam

Rigid palm oil-based polyurethane/kenaf fibre biocomposite foams were prepared at various amounts of kenaf fibre (i.e. 2.5, 5.0, 7.5, 10.0 and 12.5 pphp). Effects of kenaf fibre (KF) loadings on thermal stabilities and compressive strength were investigated. The peaks detected by Fourier transform infrared (FTIR) at 3,310 cm-1 (OH stretching), 1,533 cm-1 (NH bending) and 1,510 cm-1 (CN stretching) had proved the formation of urethane linkages in the system. Results from thermogravimetric analysis (TGA) showed that the thermal stabilities of biocomposite foams were higher than that of control PU foam. Higher KF contents resulted in agglomeration of which reduced the rate of heat transfer throughout the system. The presence of intrahydrogen bonds in agglomerated KF caused more heat needs to break the bonds, thus increasing the thermal stabilities. Consequently, the agglomeration of KF created stress concentration, which reduced the compression strength of the foams with respect to the control PU foam. The presence of intra-hydrogen bonding in PU chains had surpassed the agglomeration effect, thus causing just a small reduction percentage. The foams have potentials to be used in non-load bearing applications such as insulators and wall panels

Estimation of solute transport parameter and mass transfer coefficient in nanofiltration for solvent diluted palm oil

Membrane technology has been gradually used as an alternative to the conventional purification method in various industries. In the advancement of membrane technology, important elements such as volumetric flux, rejections, mass transfer and interaction parameters have been frequently considered, particularly in the prediction of membrane performance. In this study, an estimation of mass transfer and solute transport parameters in organic solvent was conducted by using the Levenberg-Marquardt least squares method. Combined film theory/solution-diffusion model was selected and was correlated with experimental data to estimate the parameters. The mass transfer and solute transport parameters for the nanofiltration of acetone-diluted palm oil in SolSep 030306 membrane were successfully estimated. The correlation of mass transfer coefficient with feed concentration and stirrer speed were additionally described

Isolation of bioflocculant-producing bacteria from Penaeus vannamei ponds for the production of extracellular polymeric substances

Bioflocculants are essential polymers with their flocculating activity depending on the characteristics of the secreted flocculants by bioflocculant-producing bacteria. However, the characteristics of bioflocculant produced by microorganisms were not investigated profoundly. In order to better understand these characteristics, determination of extracellular polymeric substances (EPS) from bioflocculant-producing bacteria were characterized in terms of protein concentrations. A total of 51 bioflocculant-producing bacteria isolates were screened from Pacific whiteleg shrimp, Penaeus vannamei culture ponds in Setiu, Terengganu, Malaysia. Screening of bioflocculant-producing bacteria were conducted through morphological approaches followed by protein extraction using Lowry assay method. The identified bioflocculant-producing bacteria includes Corynebacterium sp., Klebsiella sp., Lactobacillus sp., Staphylococcus sp., Bacillus sp., Streptococcus sp., Vibrio spp., Neisseria sp., Serratia sp. and Yersinia sp., with the highest protein concentration of 829 mg mL-1 were attained by Staphylococcus sp. The various amounts of EPS concentration produced by different species of bacteria were dependent on their specific population growth and growth rate. Therefore, the establishment of bioflocculant-producing bacteria isolated from biofloc which showed high tendency for EPS production were performed successfully