Significance of Acoustic and Hydrodynamic Cavitations in Enhancing Ozone Mass Transfer

Assessment of both acoustic and hydrodynamic cavitations for intensifying ozone mass transfer was conducted simultaneously. Four process schemes were arranged to evaluate the effect of application of each kind of cavitation as well as both of them, on the ozone mass transfer process. All processes were conducted at pH of 3 to avoid ozone natural self-decomposition initiated by hydroxide ions (OH^?). The chemical and mechanical effects of cavitation were distinguished by using radical scavengers to suppress radical formation. The result showed that hydrodynamic and acoustic cavitations enhanced ozone mass transfer synergistically. The enhancement obtained from the acoustic cavitation was higher than that obtained from the hydrodynamic cavitation, and the chemical effects of cavitation were much significant than that of mechanical effects. The enhancement obtained due to chemical effects of cavitation was about twice the enhancement obtained due to mechanical effects when only one type of cavitation was combined with ozonation. Combination of both type of cavitation and ozonation gave the enhancement obtained due to chemical effect of 3.68 times that obtained due to mechanical effects.     

Tailoring cotton fabric with wettability gradient and anisotropic penetration of liquid by spray coating

Abstract

Comfort has been one of the most important features of clothing, particularly for sportswear, which requires an effective transport of heat and moisture from the inner to the outer side of clothing. We herein report the use of a simple technique of spray coating and commercially available water repellents for a one-sided hydrophobic and self-initiated one-way water transport cotton fabric. The highlight of this work is the simplicity of the process and choice of chemicals that can be adopted easily by any textile finishing industry. On this fabric, water was able to diffuse and penetrate the fabric structure in one direction from the hydrophobic to the hydrophilic side but was unable to go the opposite direction. The directional transport improved with smaller droplets and lower add-on achievable by higher air pressure and longer distance of spray coating. From moisture management tests, the best result was obtained with the spray coating of Phobol NB-NH at an air pressure of 3.0?kgf/cm² and a distance of 120?cm. Phobol NB-NH gave better result of transport and overall comfort properties than Phobotex RSY.     

Optimizing a novel PPG sensor patch via optical simulations towards accurate heart rates

This study proposes the design and optimization of the flexible OLED–OPD photoplethysmography (PPG) sensor patch to estimate the long time continuous heart rate. Using optical simulation, the distance between OLED–OPD and the aperture area of the OLED–OPD has been optimized to enhance the AC/DC ratio of the receive PPG signal. The optical simulation incorporates an empirical optical skin model. All the patches incorporate green OLED@525 nm wavelength and red OLED@630 nm wavelength. Simulation results show that the optimized AC/DC ratio of the cross-type patch for the green and the red OLED is 2.16% and 6.25%, respectively. Similarly, the optimized AC/DC ratio of the square-type patch for the green, and the red OLED is 9.6% and 5.8%, respectively. Experiment results show that the received PPG signal AC/DC ratio for the square type and cross-type are 2%@green OLED and 4.5% @green OLED, respectively. Also, the AC/DC ratio of the received PPG signal from the square type and cross-type are 1.4%@red OLED and 1.1%@red OLED, respectively. The AC/DC ratio is reduced because the skin and blood itself act as a lossy medium so that the DC signal increased more; as a result, the overall AC/DC ratio decrease. The best design of the optical patch is the square-type OPD patch due to the wide area of the OPD. The OLED drive current ranges between 0.1 and 0.4 mA. The average OPD current is 800 nA. The flexibility of the design PPG sensor patch is 130°. The non-invasive square-type PPG sensor patch is applied to the wrist artery of 40 subjects for sensing the PPG pulsation of the blood vessel. The heart rate measurement accuracy is 95%, whereas the standard error rate is 0.37 ± 1.96 bpm, respectively.

     

Intelligent fault diagnosis system of induction motor based on transient current signal

This paper presents a method for induction motor fault diagnosis based on transient signal using component analysis and support vector machine (SVM). The start-up transient current signal is selected as features source for fault diagnosis. Preprocessing of transient current signal is performed using smoothing and discrete wavelet transform to highlight the salient features of faults. In this work, independent component analysis, principal component analysis and their kernel are performed to reduce the dimension of features and to extract the optimal features for classification process. In this work, the influence of the number of component analysis towards diagnosis accuracy is also studied. SVM multi-class classification using one against all strategy is selected for classification tool due to good generalization properties. Performance of the system is validated by applying the system to induction motor faults diagnosis. According to the result, the system has potential to serve an intelligent fault diagnosis system in real application.     

Adhesion study of tetra methyl cyclo tetra siloxanes (TMCTS) and tri methyl silane (3MS)-based low-k films

Chemical vapor deposited (CVD) low-k films using tri methyl silane (3MS) precursors and tetra methyl cyclo tetra siloxanes (TMCTS) precursors were studied. Films were deposited by means of four processes, namely, O₂, O₂ + He process and CO₂, CO₂ + O₂ process for 3MS and TMCTS precursors, respectively. Interfacial adhesion energy (G_c), of low-k/Si samples, as measured by a 4-point bending test displayed a linear relationship with film hardness and modulus. Fractography studies indicated two possible failure modes with the primary interface of delamination being either at low-k/Si or Si/epoxy interface. In the former, once delamination initiated at the low-k/Si interface, secondary delamination at the Si/epoxy and epoxy/low-k interfaces was also observed. Films with low hardness (<5 GPa) displayed a low G_c (<10 J/m²) with an adhesive separation of Si/epoxy, epoxy/low-k, and low-k/Si interfaces. Whereas, films of high hardness (>5 GPa) displayed interfacial energies in excess of 10 J/m² with separation of Si/epoxy and epoxy/low-k interfaces, thus indicating excellent adhesion between the Si and low-k films. Films with high hardness have less carbon in the system causing it to be more “silicon dioxide” like and exhibiting better adhesion with the Si substrate.     

Design of optimal-control systems with prescribed closed-loop poles

A new design procedure for linear systems is proposed to find the feedback vector and the weighting matrix of a quadratic performance index, which can be directly determined by the characteristic equations of the open- and closed-loop system, in order that the performance index is minimised and that the closed-loop system can achieve a set of prescribed poles.     

Textile-based microfluidics: modulated wetting,mixing, sorting,and energy harvesting

Microfluidics technology allows us to perform rapid and massively parallel manipulation and characterization of fluid samples with biomedical and environmental importance. In the attempt to achieve resource-efficient fabrication and operation of the microfluidic devices, paper-based and thread-based microfluidics have been previously demonstrated by other researchers. We propose to develop textile-based microfluidics, formed by three-dimensional networks of individual threads, to further advance the ability of paper-based and thread-based microfluidics. This paper describes four different phenomena that we investigate in textile-based microfluidic systems: modulated wetting, liquid mixing, liquid sorting, and energy harvesting. Our results indicate the feasibility of textiles as a new platform to develop low-cost microfluidic technology.     

Machine health prognostics using survival probability and support vector machine

Prognostic of machine health estimates the remaining useful life of machine components. It deals with prediction of machine health condition based on past measured data from condition monitoring (CM). It has benefits to reduce the production downtime, spare-parts inventory, maintenance cost, and safety hazards. Many papers have reported the valuable models and methods of prognostics systems. However, it was rarely found the papers deal with censored data, which is common in machine condition monitoring practice. This work concerns with developing intelligent machine prognostics system using survival analysis and support vector machine (SVM). SA utilizes censored and uncensored data collected from CM routine and then estimates the survival probability of failure time of machine components. SVM is trained by data input from CM histories data that corresponds to target vectors of estimated survival probability. After validation process, SVM is employed to predict failure time of individual unit of machine component. Simulation and experimental bearing degradation data are employed to validate the proposed method. The result shows that the proposed method is promising to be a probability-based machine prognostics system.     

On the Interpretation of °Brix Value for the Juice of Acid Citrus

°Brix, which has been commonly used for expressing the juice quality of the so-called table citrus, has been frequently used also for expressing the juice quality of acid citrus despite no definitive information being available on how good °Brix is for this purpose. Therefore a study to elucidate correlations between °Brix with acid and sugar contents in the juice of acid citrus was carried out. The results showed no correlation at all between °Brix and acid content or sugar-to-acid ratios and low, though significant, correlations between °Brix and sugar contents. °Brix or total soluble solid content seemed to be less informative for expressing the juice quality of acid citrus fruits than for measuring acid and sugar contents individually.