Rancang Bangun Antena Mikrostrip Triangular Patch Planar Array 2x2 Elements Frekuensi 1,2 GHz untuk Penerima Video Wireless LCD Projector

LCD projectors are widely used to support presentations on teaching and learning activities, meetings, seminars and so on. This study discusses the design and manufacture of a 2x2 planar array triangular patch microstrip antenna as a receiving antenna for wireless LCD projectors to overcome cable length limitations. The research method starts from the design, simulation of design results, fabrication, parameter measurement and antenna testing. The design was carried out using the CST Studio Suite application, then made on the FR-4 PCB. Testing includes measurement of antenna parameters and performance. In testing the antenna parameters, the values ​​obtained are in accordance with predetermined specifications, gain above 3 dB, VSWR below 2 dB, return loss below -10 dB and unidirectional radiation pattern. The antenna performance test results show that the quality of signal and video reception from the microstrip receiving antenna that has been made is still better than the default antenna for the receiver device. Keywords: Microstrip triangular patch plannar 2x2 elements, wireless LCD projector

Performance evaluation of conductive tracks in fabricating e-textiles by lock-stitch embroidery

Lock-stitch embroidery has been the centre of much interest as a versatile and precise method of producing conductive tracks in the fabrication of wearable electronic devices. However, improper fabrication parameter settings could result in the nonconformity of the conductive tracks and damage the conductive coating of the conductive yarns. In this study, we evaluate the appearance quality, dimensional stability and electrical resistance of conductive tracks by taking into account the embroidering speed (ES), stitch length (SL), needle thread pre-tension (NTP) and embroidering direction (ED). The conductive tracks are embroidered onto knitted fabric in different directions with silver-coated polyamide yarn as the needle thread. The results show that stitching the conductive tracks in the wale direction results in a more uniform stitch lines in comparison to the other directions. To resolve the problem of floated stitches, it is recommended that an SL of 4 mm and a higher NTP are used. The percentage of shrinkage in the wale direction is lower than in the course direction. The electrical resistance of the conductive tracks increases with a higher ES and shorter SL. It is also found that a thicker yarn is more sensitive to the NTP and some of the silver coating is rubbed off with an NTP of 50 gf. We also carry out an overlay plot analysis, through which we predict and validate the optimal embroidery parameters that balance appearance quality and electrical resistance. The technique parameters in this study can be used to embroider conductive tracks for smart clothing.

Using Dimensionless Numbers to Predict Centrifugal Jet-Spun Nanofiber Morphology

In this study, we report a method for predictive, controlled, and highly aligned nanofiber production via Centrifugal Jet Spinning (CJS) using polycaprolactone (PCL) as a model polymer. We investigated the effects of fabrication conditions and their resulting dimensionless parameters, namely the Weber, Reynolds, and Capillary numbers, by correlating with fiber morphologies (fiber diameter, fiber alignment, bead frequency, bead aspect ratio, and scaffold porosity) and mechanical properties (linear modulus and ultimate tensile strength). We report a fabrication parameter lookup table based on the aforementioned dimensionless numbers, for the production of nanofiber scaffolds using the CJS. We built a scaled-up version of the CJS that uses a larger reservoir and successfully validated the reported lookup table for PCL as well as other polymers including polyethylene oxide, polylactic acid, and polyvinylpyrrolidone dissolved either in hexafluoroisopropanol or chloroform. We show that by carefully tailoring the polymer intrinsic properties and the Reynolds number, we can fabricate bead-free, continuous fibers. This method will allow other researchers to design and build their own CJS for the production of desired fiber scaffold networks by utilizing the appropriate dimensionless numbers for their system.

Influence of Fabrication Parameter on the Nanostructure of SiNWs under HF/AgNO3/Fe(NO3)3 Etching System

Large-area SiNWs has been successfully fabricated through one-step metal-assisted chemical etching process at room temperature. The effects of key fabrication parameters (AgNO3 concentration, Fe (NO3)3 concentration, and etching time) on the nanostructure SiNWs were carefully investigated by SEM, TEM, respectively. The results show that AgNO3 concentration and Fe (NO3)3 concentration play important roles to the lengths and arrangements of SiNWs arrays in one-step MACE. The morphological transition of Si surfaces from solid nanowires to porous nanowires can be found with increasing AgNO3 concentration and Fe (NO3)3 concentration, which indicates that the re-dissolved Ag+ would work as the main oxidative species for oxidizing the silicon substrate and forming SiNWs in the HF/ AgNO3/ Fe (NO3)3 etching system. The length of SiNWs is increased with increasing AgNO3 concentration from 0.005 mol/L to 0.02 mol/L and etching time, the chemical polish phoenomenon can be observed when the Fe (NO3)3 concentration increases to 0.5 mol/L. A novel mechanism is proposed to explain the formation of SiNWs in HF/ AgNO3/ Fe (NO3)3 solution.

The Effects of Evaporation Time on Morphological Structure of Polysulfone/Cellulose Acetate Phthalate/Polyvinylpyrrolidone (PSf/CAP/PVP) Blend Membranes

Evaporation time is one of the important membrane fabrication parameter that can be manipulated in order to produce the desired membrane morphology in ultrafiltration (UF) separation process. The morphology of UF membrane has a significant effect on structural properties and performance of UF membrane. In this study, flat sheet asymmetric polysulfone/cellulose acetate phthalate/polyvinylpyrrolidone (PSf/CAP/PVP) blend membranes were prepared at different evaporation time in the range of 0 to 20 s to investigate its effect on the morphological structures of the blend membranes. The morphological structure of these blend membranes were characterized by using Scanning Electron Microscopy (SEM). The results showed that in the absence of evaporation time, the morphology of blend membrane consits of open finger-like structure and microvoids. Introduction of evaporation time period between 5 to 10 s, produced spongy blend membranes with less finger-like structure. Further increment of evaporation time between 15 to 20s, formed incomplete dense structure with small microvoids PSf/CAP/PVP blend membranes.

The Influence of SS316L Foam Fabrication Parameter Using Powder Metallurgy Route

Metal foams are widely produced by using different techniques such as compaction and replication method. In this study, slurry method also known as replication method has been used to produce SS316L foams. SS316L powders (50wt% and 60wt%) were mixed with the binders and distilled water by using mechanical stirrer. Polyethylene Glycol (PEG) and Carboxyl Methyl Cellulose (CMC) were used as binders. Polyurethane (PU) foam was used as scaffold and dipped into SS316L slurry then dried in room temperature for 24 hours. Sintering process has been done in two different temperatures which were 1200°C and 1300°C in vacuum furnace. The morphological study was performed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX). The SEM micrograph showed that the cells were interconnected and the structures become denser as the sintering temperature increase. The average pores size is ranging from 252.8 μm-353.8 μm, while strut size ranging from 50.2 μm-79.9 μm based on SEM micrograph analysis. The elemental analysis from EDX showed the element presence in the SS316L foam remain from SS316L powder which are Chromium (Cr), Nickel (Ni), Molybdenum (Mo), Cooper (Cu), Nitrogen (N2), Sulphur (S) and Silicon (Si). Higher sintering temperature contributes better grain growth between particles where the point-contact between the particles expanded and disappear the small pores.