This paper presents a method for the performance improvement of a shunt active power filter (SAPF) using the indirect current control (ICC) scheme. Compared to the conventional direct current control (DCC) scheme, the ICC gives better performance with a lower number of sensors. A simplified and efficient control algorithm using a low cost Intel 80C196KC microcontroller is implemented using only two current sensors for the source current and one voltage sensor for the DC-link voltage of the SAPF circuit. The objective is to eliminate harmonics and to compensate the reactive power produced by non-linear loads such as an uncontrolled rectifier feeding an inductive load. The APF is realized using a three phase voltage source inverter (VSI) with a dc bus capacitor. Experimental results are presented to prove the better performance of the ICC method over the DCC one.
Purpose This study aims to explore the incorporation of starch nanoparticles (SNPs) in cross-linking formulation of cotton fabrics to see their impact on fabric performance like tensile strength, dry wrinkle recovery angles, elongation at break, degree of whiteness and increase in weight as well as durability. Design/methodology/approach SNPs of size around 80-100 nm were successfully prepared from native maize starch by Nano precipitation technique and confirmed instrumentally by scanning electron microscope (SEM), transmittance electron microscope (TEM), Fourier transformer infrared (FTIR) spectroscopy and particle size analyzer. The latter were incorporated in cross-linking formulation of cotton fabrics encompassing different concentrations of citric acid and sodium hypophosphite at different curing time and temperature in 100 ml distilled water to a wet pickup of ca. 85 per cent. The fabric samples were dried for 3 min at 85°C and cured at specified temperatures for a specified time intervals in thermo fixing oven according to pad-dry-cure method. Findings FTIR spectra and SEM micrograph signified the chemical structure and surface morphology of cotton fabric before and after finishing in absence and presence of SNPs. Cotton fabric samples finished in presence of SNPs showed a higher tensile strength, elongation at break, comparable dry wrinkle recovery angles and degree of whiteness than that finished in their absence. On the other hand, the enhancement in the aforementioned performance reflects the positive impact of incorporation of SNPs in textile finishing especially with strength properties; which are one of the important requirements for industrial fabrics that can be used widely in heavy-duty applications. Research limitations/implications SNPs with its booming effect with respect to biodegradability, reactivity and higher surface area can be used as a novel reinforcement permanent finish for cotton fabrics instead of more hazardous materials likes poly acrylate and monomeric compounds. Practical implications As SNPs biopolymers is one of the important reinforcement agents, so it was expected that it would minimize the great loss in strength properties during easy-care cotton finishing and improve the fabric performance. Originality/value The novelty addressed here is undertaken with a view to remediate some of the serious defects of easy-care cotton fabrics using poly carboxylic acids; especially with the great loss in strength properties by virtue of using SNPs as a permanent finish. Besides, to the authors’ knowledge, there is no published work so far concerning the use of SNPs as an innovative base for production of easy-care finished cotton textiles with high performance.
To minimize the serious defects of durable press finishing of cellulosic textiles with respect to the great loss in strength properties, new pioneering strengthening approach of cotton fabric based on our previously prepared starch nanoparticles of size around 80–100 nm was used. For this purpose, cotton fabrics were treated with different concentrations of starch nanoparticles via coating technique using pad-dry-cure method, at which the starch nanoparticles are attached to the fabrics with the use of a padder adjusted to appropriate pressure and speed, followed by drying and curing. Fabric stiffness, surface roughness, tensile strength, elongation at break, abrasion resistance, wrinkle recovery angles, add-on %, and degree of whiteness as well as durability of treated fabrics were fully explored. SEM was used for detecting the change in surface morphology of reinforced coated fabric. The results obtained reflect the following findings: (a) all fabric performance like tensile strength, stiffness, wrinkle recovery angle, abrasion resistance and add on % were improved for coated fabrics with starch nanoparticles in comparison with untreated fabric, except that of surface roughness; (b) SEM confirmed the change in surface morphology of cotton fabric after reinforcement treatment using starch nanoparticles; (c) the dry wrinkle recovery angle and tensile strength of cotton fabrics treated in presence of 30 g/l starch nanoparticles are slightly decreased after 10 washing cycles as compared with untreated fabric; and (d) starch nanoparticles introduce an advance in textile finishing with respect to the above-mention fabric performance except that of surface roughness.
Trapezoidal cross-sectional spiral microfluidic channels showed high resolution and throughput in cell separation in bio-applications. The main challenges are the complexity and high cost of the fabrication process of trapezoidal cross-sectional channels on the micro-scale. In this work, we present the application of grayscale in microfluidic channel design to overcome the complexity of the fabrication process. We also use direct engraving with a CO2 laser beam on polymethyl methacrylate (PMMA) material to drastically reduce the microfluidic chip’s cost (to <30 cents) and fabrication time (to 20 min). The capability of the present fabrication methodology for cell sorting applications is demonstrated through experimental tests for the separation of white blood cells (WBCs) from whole blood at different dilution factors. The experimental results indicated that an 800 µL/min flow rate provided the optimal separation efficiency using the fabricated chip. A 90.14% separation efficiency at 1% hematocrit diluted blood sample was reported.
Free space optics (FSO) is a promising technology for high data rate transmission where data is transmitted wirelessly from one place to another. It has a variety of applications nowadays including indoor, outdoor, underwater, and deep space communications. However, the availability of link under various atmospheric conditions is a major concern. In this study, we evaluate the transmission of 128 Gb/s optical quadrature phase shift keying (QPSK) signal under different weather conditions and pointing errors. Simulation parameters such as FSO link range, atmospheric attenuation, pointing loss, and wavelength are taken into consideration. The system performance evaluation parameters including eye diagram, constellation, and received signal to noise ratio (SNR) are compared to find the best performance under different weather conditions. Numerical simulations show that the pointing errors up to 10 µrad and bad weather conditions up to 15 dB attenuation has sever effects on the system performance and we should use digital signal processing and equalization to enhance it.
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