Development and characterization of warp knitted spacer fabrics for helmet comfort liner application

The inner padding layer of the motorcycle helmet is one of the important components that control the factors of comfort during wearing the helmet and provides a perfect fit and stability of the helmet on the head. The inner padding consists of a low-density flexible polyurethane layer attached to a soft fabric layer that is in direct contact with the head. The present study aims to replace foam in the comfort liner of a helmet with spacer fabrics to avoid the risk of heat stress during the use of the helmet. In this work, 9 warp-knitted spacer fabrics were produced by varying the course/cm (10, 12 & 14) and thickness (3, 3.5, and 4 mm). Air permeability, thermal, and water vapour resistance of the developed spacer fabrics were characterized along with compression properties and compared with commercially available standard liner. The results showed that warp-knitted spacer fabrics had better energy absorption compared to the standard liner. Also, the developed spacer fabrics had better breathability and evaporative heat transfer compared to the standard liner.

Slotted Wearable Antenna for WLAN and LTE Applications

Slotted wearable antenna is designed at frequency 2.4 GHz due to its application for wireless application and radiolocation. Proposed antenna is used for radiolocation through which detection of objects is possible using a tracking system of radio waves by analyzing the properties of received radio waves. Proposed design employs denim material as a substrate with copper patch as conducting layer. Denim fabric layer of 1mm thickness with permittivity of 1.7 and loss tangent of 0.025 is used as substrate. Dimensions of proposed antenna are calculated using a transmission line model. Proposed antenna has bandwidth percentage of 46% with center frequency 2.42 GHz, and it has high radiation efficiency 93.69%. It covers the frequency range between 2.18 GHz and 3.49 GHz, which works on WLAN applications (2.4-2.484 GHz) and LTE band (2.17 GHz).

Smart Line Judgement System: A Novel Technology in Vol-leyball Arbitration

<p class="BodyText1">Within previous decade, sensitivity to arbitration systems in sports such as soccer, tennis and volleyball has been sharply increased and technicians turned to new technologies to fulfill the demands for a reliable judgement. The main purpose of this study was to address a new method in judgement of presence of ball in the volleyball field in the shortest possible time by manipulation of lines surrounded the field and the ball layer’s structure. A carbon semi- conducting fabric layer designed ball was thrown to the printed circuit board (PCB), which have replaced the surrounded field lines. The ball was thrown in six different angles of 15, 30, 45, 60, 75, and 90 degrees and with 20 and 40 m.s-1 speed. As soon as the semiconducting ball hits the PCB lines, the LED, which embedded under the PCB, turns on and announce the presence of the ball in the field. In 20 m.s-1 speed, the PCB detected 97.1% of ball presence in the field per 1500 trials six angles. Almost similar, in 40 m.s-1 speed, the accuracy of PCB in hit detection was 97.6% per 1500 trails. Additionally, regardless of ball speed, the more perpendicular the ball hit the PCB line, the accurate detection was made. The smart line judgment system could be a reliable, efficient, and affordable technology that provide referees with an accurate decision and athletes with a faster game flow. </p>

Characterization and statistical modelling of thermal resistance of cotton/polyester blended double layer interlock knitted fabrics

The aim of this study was to analyse and model the effect of knitting parameters on the thermal resistance of cotton/polyester double layer interlock knitted fabrics. Fabric samples of areal densities ranging from 310-495 g/m2 were knitted using yarns of three different cotton/polyester blends, each of two different linear densities by systematically varying knitting loop lengths for achieving different cover factors. It was found that by changing the polyester content in the inner and outer fabric layer from 40 to 65% in the double layer knitted fabric has statistically significant effect on the fabric thermal resistance. Fabric thermal resistance increased with increase in relative specific heat of outer fabric layer, yarn linear density, loop length, and fabric thickness while decrease in fabric areal density. It was concluded that response surface regression modelling could be successfully used for the prediction of thermal resistance of double layer interlock knitted fabrics. The model was validated by unseen data set and it was found that the actual and predicted values were in good agreement with each other with less than 10% absolute error. Sensitivity analysis was also performed to find out the relative contribution of each input parameter on the air permeability of the double layer interlock knitted fabrics.