Key Engineering Materials Vols. 594-595

Abstract: The effect of 10, 30 and 50 % volume of Olein oil, Glycerol and Crude Palm Oil (CPO) as plasticizer on the thermal performance of biopolymer has been investigated in this paper. The biopolymer was developed from a new source of starch, Tacca leontopetaloides, and natural rubber by using two roll-mill. Changes in functional groups and thermal performance of formulated bio-Thermoplastic elastomer (TPE) were analyzed by Fourier Transform Infrared (FTIR) and Thermogravimetric Analyzer (TGA). Increased volume of Olein oil and glycerol resulted to increasing strength of hydrogen bonding in the intermolecular TPEs, therefore it has high thermal resistant towards high temperature. Conversely, increased volume of CPO decreased the strength of hydrogen bonding in structural starch and CPO therefore TPE with CPO shows high degradability which possess up to 100 % weight reduction at 500 0C.

Abstract: The presence of missing values in statistical survey data is an important issue to deal with. These data usually contained missing values due to many factors such as machine failures, changes in the siting monitors, routine maintenance and human error. Incomplete data set usually cause bias due to differences between observed and unobserved data. Therefore, it is important to ensure that the data analyzed are of high quality. A straightforward approach to deal with this problem is to ignore the missing data and to discard those incomplete cases from the data set. This approach is generally not valid for time-series prediction, in which the value of a system typically depends on the historical time data of the system. One approach that commonly used for the treatment of this missing item is adoption of imputation technique. This paper discusses three interpolation methods that are linear, quadratic and cubic. A total of 8577 observations of PM₁₀ data for a year were used to compare between the three methods when fitting the Gamma distribution. The goodness-of-fit were obtained using three performance indicators that are mean absolute error (MAE), root mean squared error (RMSE) and coefficient of determination (R²). The results shows that the linear interpolation method provides a very good fit to the data.

Abstract: Grain size and homogeneity are influence to aluminium properties, Equal channel angular pressing (ECAP) can produce aluminium with ultra fine grain Size (UFG). The grain size is depends on ECAP Dies geometry (Channel angle Φ, Fillet radius ψ) and friction, taguchi method used to find the optimum dies geometry its can produce smaller grain size and homogeny. Modeling done with channel angels 90, 105 and 120°, fillet radius (inside) 1.5, 5,0 and 10 mm ; fillet radius (outside) 1.5, 5,0 and 10 mm and friction 0, 0,025 and 0,05. Modeling used L9 taguchi matrix, the most homogeny dies is ECAP dies with channel angel 105°, fillet radius (inside) 10 mm ; fillet radius (outside) 0 mm and friction 0,025

Abstract: Almost all real life datasets consist missing values. These are usually due to machine failure, routine maintenance, changes in siting monitors and human error. The occurence of missing values requires special attention on analysing the data. Incomplete datasets can cause bias due to systematic differences between observed and unobserved data. Therefore, the need to find the best way in estimating missing values is very important so that the data analysed is ensured of high quality. In this research, three types of mean imputation techniques that are mean, mean above and mean above below methods were used to replace the missing values. Annual hourly monitoring data for PM₁₀ were used to generate missing values. Four randomly simulated missing data were evaluated in order to test the efficiency of the methods used. They are 5%, 10%, 15%, 25% and 40%. Three types of performance indicators that are mean absolute error (MAE), root mean square error (RMSE) and coefficient of determination (R²) were calculated to describe the goodness of fit for all the method. From all the method applied, it was found that mean above below method is the best method for estimating data for all percentages of simulated missing values.

Abstract: Recently, manufacturing process simulation using finite element (FE) model become important. Therefore, validation of the finite element model is crucial. This study will present validation of 2D finite element simulation of cold heading at room temperature. Validation of the simulation model is carried out by comparing the resulted bulge profile of the cold upsetting specimen to the profile of the specimen, which is obtained from an optical 3D surface measurement technique namely Infinite Focus Alicona system. Based on the result, both profiles show a very good agreement.

Abstract: Uninterruptible power supply (UPS) sits between a power supply such as wall outlet and devices to prevent undesired feature that can occur within the power source such as outages, sags, surges and bad harmonics from the supply to avoid a negative impact on the devices. This paper presents a photovoltaic (PV) powered UPS using microcontroller PIC16F628A-I/P. It is a standby UPS whereas if the main power source fails to supply power to loads, a battery powered inverter turns on to continue supplying power. The battery is charged by the PV using solar charger and transfer switch controlled by the microcontroller. The UPS was tested to a load of 240 V, 20 W AC aquarium water pump. The test result shows that the UPS perform well, when the main power source fails, the battery could power inverter and the microcontroller controls the transfer switch of the UPS inverter and the main power source.

Abstract: This paper presents the design and development of tracking system for the mines detector robot. The scope for the tracking system covers two important tasks: 1. Design of optimum tracking path to cover maximum scanning area of an enclosed field, and 2. Obstacles avoidance system to be able avoid the various types of obstacles during the scanning process. The tracking algorithms were designed and simulated using Webots simulation software. Upon successful simulation where all design objectives have been achieved, the algorithms were programmed in microcontroller to implement the tracking system on the mines detector robot. Experimental test rig for the robot was a flat surface, enclosed 3m x 3m area where several obstacles of different sizes and shapes were randomly placed. Several metal samples representing the metal detonator of minefield were also placed to test the sensing system of the robot. Infra-red (IR) sensors were used for the system to detect the obstacles and also to detect the end-path boundary of a routine scanning cycle. While simulation test results have shown achieved design objectives, experimental results shown 90% achievement and limitation on evading big size of circle-type obstacle.

Abstract: This paper presents the design and development of sensing system for mines detector robot. The objective of this project is to identify the optimum metal detection system and design and develop the sensing system of mines detection circuit for the landmine mobile robot. This sensing circuit of landmines detection system consists of pulse generation circuit, detector circuit, amplifier circuit, comparator circuit, microcontroller PIC18F4580 and the display result circuit through LCD screen. Size, type and shape of ferrous and non-ferrous object (landmines) will impinge on the output voltage signal from the search coil. The metal (iron) that was targeted in this project will be chosen based on an artificial detonator. Experimental results showed that this circuit able to sense ferrous and non-ferrous object (landmines) with satisfy sensitivity and consistent result.

Abstract: A two-dimensional adhesively bonded dissimilar single lap joint model was analyzed under tension. An explicit closed-form solution was formulated by using MATLAB tool for analysis of shear and peel stresses distribution along the bondline under effect of variation of overlap length, adherend thickness ratio and adherend Youngs modulus ratio. The solution was formulated based on analysis of Bo Zhao et al. [2]. The bending moment at the edge joint of the Bo Zhaos solution was replaced by the bending moment at the edge joint that have been proposed by X. Zhao et al. [5] to compare the accuracy of solutions. The least stress intensities in dissimilar joint could be achieved with a suitable ratio of thickness and Youngs modulus of adherends.

Abstract: This paper evaluates the feasibility and effectiveness, within controlled conditions of an active pitch catch sensing PZT sensors on two panels and an aircraft structure made from carbon fiber reinforced plastic (CFRP) pre-impregnated materials. Once cured, the exhibits were subjected to partial and full penetration damages. Two PZT sensors each acting as an actuator and receiver were placed across the investigated region at 100mm apart. Three conditions were set on each panel for each undamaged, damaged and repaired area. Fifty readings were carried out on each panel for each condition. Feature extraction of the wavelet propagations were applied for the post processing from the captured Lamb wave data. The aircraft structure was also used to acquire data with the same above condition. A promising result shows that the interrogation of the actuating PZT sensors can differentiate the studied condition for both panels and structure. In addition, distinguished wavelet patterns were contributed by the surface irregularities due to damage and additional repair plies for both panels and aircraft structure.