Surface defect characterisation using non-contact ultrasound

Electromagnetic acoustic transducers (EMATs) have been used as a non-contact ultrasound approach for detecting and characterising surface defects in aluminium bars and billet. The characterisation was made from understanding the interaction of broadband Rayleigh surface waves with surface crack growing normal or inclined to the sample surface, based on rolling contact fatigue (RCF) cracks in rail tracks. The interaction with normal cracks have been previously reported. For inclined cracks, mode conversion of Rayleigh waves to Lamb-like waves occur in the wedge section formed by the crack, resulting in strong and prominent enhancement in the signal detected. This is confirmed by finite element analysis (FEA) models and Lamb waves arrival times calculation. Signal enhancement from the interaction creates features in B-scan images, and they have been used for initial crack classifications. Then, a number of analyses were performed to estimate the crack inclination, and accurately determine the crack vertical depth. A feature extraction and image classification program based on genetic programming have been developed (through a collaboration work) to perform automated classification on the B-scans. The program produces more than 90% accuracy using the experimental data set. The viability of EMATs to detect and fully characterise narrow cracks have been investigated through experiments using laser interferometer and comparison with EMATs measurements. The results confirmed that narrow cracks can be detected with EMATs, with initial classification (in B-scans) to normal/inclined. However, the depth sizing may not be accurate, and suggestion for better designs of EMATs have been made. FEA models have been used to study the interaction of the Rayleigh waves with branched cracks. Interesting results are observed in terms of Rayleigh waves reflections, which helps to determine the presence of a branch on RCF-like cracks. A method has been proposed for calculating the length of the branch, following a number of analyses

Scanning laser source and scanning laser detection techniques for different surface crack geometries

Standard test samples typically contain simulated defects such as slots machined normal to the surface. However, real defects will not always propagate in this manner; for example, rolling contact fatigue on rails propagates at around 25º to the surface, and corrosion cracking can grow in a branched manner. Therefore, there is a need to understand how ultrasonic surface waves interact with different crack geometries. We present measurements of machined slots inclined at an angle to the surface normal, or with simple branched geometries, using laser ultrasound. Recently, Rayleigh wave enhancements observed when using the scanning laser source technique, where a generation laser is scanned along a sample, have been highlighted for their potential in detecting surface cracks. We show that the enhancement measured with laser detector scanning can give a more significant enhancement when different crack geometries are considered. We discuss the behaviour of an incident Rayleigh wave in the region of an angled defect, and consider mode-conversions which lead to a very large enhancement when the detector is close to the opening of a shallow defect. This process could be used in characterising defects, as well as being an excellent fingerprint of their presence

Non-contact ultrasonic detection of angled surface defects

Non-destructive testing is an important technique, and improvements are constantly needed. Surface defects in metals are not necessarily confined to orientations normal to the sample surface; however, much of the previous work investigating the interaction of ultrasonic surface waves with surface-breaking defects has assumed cracks inclined at 90° to the surface. This paper explores the interaction of Rayleigh waves with cracks which have a wide range of angles and depths relative to the surface, using a non-contact laser generation and detection system. Additional insight is acquired using a 3D model generated using finite element method software. A clear variation of the reflection and transmission coefficients with both crack angle and length is found, in both the out-of-plane and in-plane components. The 3D model is further used to understand the contributions of different wavemodes to B-Scans produced when scanning a sample, to enable understanding of the reflection and transmission behaviour, and help identify angled defects. Knowledge of these effects is essential to correctly gauge the severity of surface cracking

Scanning laser techniques for characterisation of different surface breaking defect geometries

Measurements using a laser scanning system consisting of a pulsed Nd:YAG laser to generate surface ultrasonic waves and an interferometer to detect the surface displacement, are presented for different samples and defect geometries. We show, firstly, details of the interaction of Rayleigh waves in thick samples with machined slots inclined at an angle to the surface normal, or with simple branched geometries, scanning the generation source over the defect (SLLS) or scanning the detection point over the defect (SLD). Secondly, we discuss effects of Lamb waves interacting with V-shaped defects in thin samples. The results from these measurements have shown that the signal enhancement found in the near-field in both cases can be used to position the defect and gain an idea of its geometry, and have shown this to be a suitable fingerprint of the presence of the defect

History of Islamic political movements in Turkey

This article investigates the history of Islamic political movements in Turkey. The time period of the article cover the time after the establishment of the Republic of Turkey in 1923 to the year 2000. It is argued in the article that Islamic movements were largely suppressed in the period between 1923-1945 when the country was ruled with a single party regime led by the Republican Peoples Party. With the introduction of multi-party political system in 1945, political Islam found the opportunity for political activism in the body of Democrat Party. But the political Islam found a more organized opportunity with the establishment of National Order Party in 1970 and National Salvation Party in 1971 by Necmettin Erbakan. Based on a programme of National View, the Turkish political Islam was known for its aim to support material development with a parallel moral and spiritual development with a reaction to the west in interstate relations. Turkish political Islam expressed itself with Welfare Party in 1983 to function until 1998 with some clear changes in its programme particularly in its agreement with contemporary political institutions and later support for Turkey’s integration with the west. Turkish political Islam experienced its first great electoral success during the WP period. However, the WP is closed down in 1998 by the Constitutional Court due to allegations about anti-secularism and driven to a process of breakdown. © 2015, Canadian Center of Science and Education. All rights reserved

Incorporation of Pleurotus sajor-caju powder in cinnamon biscuit: study on nutritional, physical, colour and sensorial properties

Discovery of novel dietary fibre (DF)-rich food ingredient is of great interest to meet the rising consumer demand for healthy food. Intake of DF-enriched food has been positively associated with a decreased risk of chronic diseases. Pleurotus sajor-caju (PSC), one of the prominent edible mushrooms widely cultivated in Malaysia, is useful for its culinary and medicinal purpose. This study aimed to determine the nutritional, physical, colour and sensorial properties of cinnamon biscuit formulated with PSC powder as partial replacement (0, 4, 8 and 12%) for wheat flour. Results indicated that elevated incorporation levels of PSC powder significantly (P<0.05) increased nutritional values of cinnamon biscuits; with 12% PSC cinnamon biscuit recorded the highest DF (9.84%), protein (7.85%) and ash (1.00%) content. In texture profile analyses, slight increment in firmness and reduction in crispiness of the cinnamon biscuits were detected with increasing levels of PSC powder. PSC-enriched cinnamon biscuits were reported to have lower L* value (ranged from 65.49 to 69.25) compared to control cinnamon biscuit (70.84), indicating darker surface colour. In comparison to control cinnamon biscuit, incorporation of PSC powder up to 8% produced higher scores in term of aroma, colour and appearance. In summary, incorporation of 8% PSC powder could be an effective way to develop nutritious cinnamon biscuit without jeopardizing its desirable physical and sensorial properties

Potential and Electric Field Characteristics of Broken Porcelain Insulator

Overhead line insulators can be damaged for various reasons during their service life. Porcelain or glass insulators once damaged can affect the reliability of power system networks. This paper presents the study of voltage and electric characteristics along the surface of a broken porcelain insulator located in a string of 10 unit insulators. Three models of broken porcelain insulators were being proposed and the analysis results on voltage and electric characteristics were individually collected. The broken porcelain insulator with the most significant effect were then being investigated in the strings of 10 unit insulators. The finite element software of Quickfield was used to analyze the voltage and electric characteristics. Form the presented results, it is proven that the single porcelain insulators with broken shed at the nearest to the electrode terminal gave the most significant effect of voltage and electric field distribution pattern along the creepage distance. However, when this type of broken insulator was included in a string of 10 unit insulators, maximum average value of voltage achieved once the broken insulator was located at the HV terminal. Meanwhile, the highest electric field strength was recorded when the broken insulator was located in the middle of the string

Potential field methods and their inherent approaches for path planning

Path Planning is one of the vital aspects in autonomous system. In path planning, safety is important issue that should be taken into account in order to ensure a robot reaches at the target location without collision with surrounding obstacles. Moreover, there are important aspects that need to be addressed in path planning; computational time, optimal path and completeness. One of the popular methods for path planning is Potential field. Potential filed method is capable to overcome unknown scenario, taking into account the realities of the current environment of the robot motion. Two type of forces involved in potential field method; attractive force generated by goals and repulsive force generated by obstacles. However, this method has a major drawback due to local minima problem. This paper reviews the traditional artificial potential field theory that has been modified with variety of algorithms based on potential field method that have been implemented to upgrade the potential function performance in obstacle avoidance and local minima problem

Growing Women SMEs: unblock the Bottleneck of Access to Finance along the Business Life Cycle

A Powerpoint presentation is available online at https://virtual.oxfordabstracts.com/#/event/1520/submission/551The paper investigates the impact of factors influencing access to finance on the growth of women-owned small and medium enterprises (WSMEs). Women entrepreneurs are frequently confronted with a lack of support and assistance, hence, less chance of financing opportunities, while developing their ventures. Despite the growing interest in WSMEs start-ups and economic growth, there is still a lack of both theoretical and empirical research on the institutional influences on WSMEs’ access to external finance and the financial needs across the BLC. Therefore, this study incorporates the institution theory and the pecking order theory, to explore how access to finance affects the WSMEs’ BLC. Additionally, the paper adopts two-approaches to further examine the phenomenon: the supply-perspective, institutional factors, including sources of finance, are explored and the demand-perspective, the financial needs across BLC. The study will utilise a qualitative approach to collect data, using face-to-face, semi-structured interviews with key participants in Mauritius

Land Cover Mapping Using High Spatial Resolution SPOT Data Over Penang Island Malaysia.

Satellite digital imagery has proved to be an effective tool for land cover changes studies. The objective of this study is to demonstrate the effectiveness of SPOT imageries in changes detection over Penang Island, Malaysia. An understanding of land use/land cover at local with high resolution is important to prepare the latest data and can be used in many purposes. The neural network classifier was performed to the satellite images and the results were compared with four standard supervised classification techniques, such as the maximum likelihood, minimum distance-to-mean and parallelepiped