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The presence of moisture and air in hydraulic oil will seriously affect the reliability of machines. This paper proposes a new cross-capacitive oil pollution detection sensor, which is based on the Thompson and Lampard theorem. The sensing unit consists of four identical copper electrodes with infinitesimally small gaps. The sensor can effectively distinguish water droplets and air bubble pollutants mixed in the oil through the pulse direction of the signal. Compared with traditional capacitive sensors, the sensor has a significant improvement in detection accuracy and detection throughput. In this paper, the relationship between the cross-capacitance value with the dielectric constant and the frequency in an alternating electric field was deduced, and the best excitation frequency was chosen as 1.9 MHz. Experiments show that the sensor can effectively detect water droplets of 140–160 µm and bubbles of 170–190 µm and has good linearity for detecting water droplets and air bubbles of different sizes. The sensor provides a new method for machine condition monitoring of hydraulic systems. [ABSTRACT FROM AUTHOR]

Due to extensive applications of microfluidic devices, manufacturing of these apparatus has recently been noticed. Production of multiple emulsions is one of the main goals of manufacturing microfluidic devices. Design and fabrication of microfluidics are functions of the size of emulsion droplets, properties of fluids applied for emulsification, and considered stability for emulsions. In this article, we have manufactured a novel microfluidic device using simple fabrication and accessible materials. Capillary tubes, PTFE (polytetrafluoroethylene) chassis, a medical needle of gauge 32, and O-rings are the primary materials used to produce this device. The production procedure is explained completely, and all the drawings are represented. Concerning probable interactions between glues and flowing fluids, we tried to fabricate and seal the device without applying chemical agents. The device is tested by n-heptane and deionized water to produce multiple water-in-oil-in-water (W/O/W) emulsions. A sensitivity analysis on the rate of injection is performed. Considering the HLB (hydrophilic–lipophilic balance) as an important property of emulsifiers, the effects of two different types of emulsifiers (sodium dodecyl sulfate with HLB of 40 and glycerol monostearate with HLB of 3.8) at various concentrations are investigated. Due to the results, the injection rate of the mediate phase should be less than half of the outer phase for the formation of emulsions. Consequently, the rate of injection for the inner phase should be less than half of that for the mediate phase. The simplicity of production and accessible raw materials could be considered as the strengths of our microfluidic device. [ABSTRACT FROM AUTHOR]

Thermal barrier coating (TBC) of turbine blades can prevent aeroengine damage resulting from high temperature. TBC exhibits a multilayer complex structure of ceramic and bonding layers. The ceramic layer is dielectric, whereas the bonding layer is conductive. Disabling either layer can endanger aircraft safety. Changes in TBC parameters are indicative of failure. This study proposed a neural-network-based method to inverse the three key parameters of TBC simultaneously based on electromagnetic/capacitive dual-module sensor. Thus, this method can be used for monitoring the status of aeroengines. The experimental results revealed that the inversion error of thickness and permittivity of the ceramic layer and the conductivity of the bonding layer is less than 2%. Therefore, the proposed method can satisfy application requirements. [ABSTRACT FROM AUTHOR]

A comparative study of electrical breakdown properties of deionized water (H2O) and heavy water (D2O) is presented with two different electrode materials (stainless steel (SS) and brass) and polarity (positive and negative) combinations. The pulsed (~a few tens of nanoseconds) discharges are conducted by applying high voltage (~a few hundred kV) pulse between two hemisphere electrodes of the same material, spaced 3 mm apart, at room temperature (~26-28 °C) with the help of Tesla based pulse generator. It is observed that breakdown occurred in heavy water at lesser voltage and in short duration compared to deionized water irrespective of the electrode material and applied voltage polarity chosen. SS electrodes are seen to perform better in terms of the voltage withstanding capacity of the liquid dielectric as compared to brass electrodes. Further, discharges with negative polarity are found to give slightly enhanced discharge breakdown voltage when compared with those with positive polarity. The observations corroborate well with conductivity measurements carried out on original and post-treated liquid samples. An interpretation of the observations is attempted using Fourier transform infrared measurements on original and post-treated liquids as well as in situ emission spectra studies. A yet another important observation from the emission spectra has been that even short (nanosecond) duration discharges result in the formation of a considerable amount of ions injected into the liquid from the electrodes in a similar manner as reported for long (microseconds) discharges. The experimental observations show that deionised water is better suited for high voltage applications and also offer a comparison of the discharge behaviour with different electrodes and polarities. [ABSTRACT FROM AUTHOR]

This paper presents a microfluidic device that can automatically transport a droplet on a plastic plate. This device consists of a Cyclo Olefln Polymer (COP) plate and a SiO2 membrane and has wettability gradient surface. Lithographic patterns of hydrophilic SiO2 permitted wettability modification of a hydrophobic COP surface. A series of alternate hydrophobic and hydrophilic wedge-shaped patterns generated a required gradient in wettability. When we dropped a droplet on the wettability gradient surface, it moved along the wettability gradient due to an imbalance between surface tension forces acting on the opposite sides of the droplet edge. The droplet transportation test was carried out using water of 5µl. As a result, we succeeded in automatically transporting the droplet on the SiO2/COP wettability gradient pattern. We also carried out droplet transportation in an enclosed microchannel for preventing droplet evaporation using DI (Deionized) water of 5µl. In this case, the droplet was automatically transported by forming the wettability gradient pattern at the top and bottom in an enclosed microchannel without evaporation. [ABSTRACT FROM AUTHOR]

A liquid membrane electrochemical etching process for preparing nano-tips is proposed by the introduction of buoyant force to the lower tip, in which the lower portion of the anodic wire is immersed into a floating layer. A mathematical model of this method is derived. Both calculation and experimental results demonstrate that the introduction of buoyant force can significantly decrease the tip radius. The lubricating oil and deionized water floating layers were tested for the processing of nano-tips. Further, high-aspect-ratio nano-electrodes were prepared by applying a relative vertical movement to the anodic wire. [ABSTRACT FROM AUTHOR]

Novel double pulse forming lines (PFLs) are fabricated with two separate coaxial single PFLs with the same dimensions with each inner cylinder of the PFL negatively charged to improve the breakdown voltage of PFL and the energy storage density of de-ionized water. A spiral line is adopted for the single PFL to raise the impedance of the PFL and prolongs the pulse duration. Ethylene glycol is mixed with de-ionized water to raise the leakage resistance and the impedance of the single PFL. A double structure is adopted to reduce the breakdown voltage requirement of the transformer and the switch. At the same time, the double structure is an advantage to raise the impedance of the PFL. [ABSTRACT FROM AUTHOR]

The helical pulsed forming line (PFL) can generate longer duration rectangular pulse in a smaller length. A compact PFL using helical water line is designed and experimentally investigated. The impedance of the helical PFL is 22 ࡎ. The compactness is achieved in terms of reduction in length of the PFL by a factor of 5.5 using helical water PFL as compared to coaxial water PFL of same length. The helical PFL was pulsed charged to 200 kV using a high voltage pulse transformer in 4.5 μs and discharged into the matched 22 ࡎ resistive load through a self-breakdown pressurized spark gap switch. The rectangular voltage pulse of 100 kV, 260 ns (FWHM) is measured across the load. The effect of reduction in water temperature on the pulse width is also studied experimentally. The increase in pulse width up to 7% more is observed by reducing the temperature of the deionized water to 5 °C. It will further reduce the length of the PFL and make the system small for compact pulsed power drivers. [ABSTRACT FROM AUTHOR]