Wireless structural health monitoring (SHM) system for damage detection using ultrasonic guided waveform response

This paper presents an improved version of a wireless device embedded with a smart PZT sensor to detect flaws and structural defects on selected investigated structure. Smart PZT sensors were used as an actuator and sensor, coupled with two XBee's and one signal generator IC chip. Programme execution on transmitting and receiving the ultrasonic guided wave via the PZT sensor had been written in MATLAB. The developed source code is basically to receive serial data from one Xbee to another remote Xbee attached to the investigated structural system. The refined waveform response is utilised for prognosis of the true structural status. The 4-mm simulated holed into one of the aluminium structural plate is benchmarked with its pristine condition in validating the effectiveness of the developed SHM wireless module. Results showed that the wave is more even in non-defected area and disrupted in affected area. Ultrasonic waves increase continuously for non-destructive evaluation and structural health monitoring in various structural applications because the guided wave can propagate long distances and reach difficult-to-access regions; for inspecting porous and some non-porous materials ultrasonic waves attenuate fast and are very useful. Recent advances in ultrasonic wave application model and results are discussed in this paper

Oblique impact analysis of cycling helmets made from kenaf (Hibiscus cannabinus) and flax (Linum usitatissimum) natural fiber

This paper describes the performance of a natural-fiber-based cycling helmet in an oblique impact with a simulated road surface. The linear accelerations and impact energy of a head form weighing 4 kg were measured and calculated. Helmet standards require helmets to be tested with a simple drop test onto an anvil. The maximum permitted deceleration of the dropped head form is typically 300g, which is equivalent to an impact velocity of 20 km/h (12.5 mph). The two helmets being tested were suspended onto a guided drop-table in the particular desired impact orientation. Just before impact, the test object was released from suspension so it can move unrestrained thereafter. The main advantage of this process is that the object is free to move naturally during impact, which provides for more realistic drop-testing. For oblique impact test, all helmets tested passed the requirement set by EN1078:2007 with linear acceleration measured lower than 250 g in a free fall test from 1.5 m platform. By comparing the resultant linear acceleration with a commercial cycling helmet, Kabuto Aero SL, flax aero helmet shows 11.82% reduction in the resultant linear acceleration with 214.16g. The Kenaf helmet recorded 168.48g, which corresponds to a 30.63% reduction in the resultant linear acceleration compared to the Kabuto helmet and 21.33% reduction compared to the Flax helmet

Effectiveness of local waste materials as organic-based coagulant in treating water

The adequacy of chemicals as coagulants such as alum is all around perceived. Nevertheless, there are numerous drawbacks related with the use including high operational costs, impeding impacts on human wellbeing and generation of huge sludge volumes. In this manner, it is crucial to supplant these chemical coagulants with organic-based coagulants to minimize the downsides. Therefore, the aim of this study is to identify the suitability of selected local wastes in becoming organic-based coagulant as to treat raw water. Regarding choice of organic-based coagulants, this study focused on the local waste materials, which are chestnut peels, bagasse and maize cobs. These waste materials were prepared by washing, drying, grinding lastly sieving in obtaining powder of coagulants ready to be used. A jar test was then performed to decide the effect of individual characteristic coagulants on the effectiveness of turbidity removal under different working variables of pH and coagulant dosage. Based on the findings, bagasse contributed to the highest yield of 79.5% followed by chestnut and maize cob. From the jar test experiments, the optimum dosage of 90 mg/L and pH 7.5 was obtained. At these optimizations, highest turbidity removal of 97.3% was recorded by bagasse compared to the other tested natural coagulants. This showing that bagasse as one of the representatives of organic wastes has the potential to physically treat the water. Keywords: Organic-based coagulant; Organic wastes; Coagulant dosage; Turbidity removal

Simulating bio-composite cycling helmet performance through FEA and CFD approaches

Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) analysis were performed in this work in order to obtain the best design for safety and aerodynamic performance of the bicycle cycling helmet. FEA analysis was computed on two different helmet designs to determine the critical area subjected to impact. A pressure load was applied on the helmets’ outer surface to simulate oblique loading. The critical areas of the helmets were then highlighted and identified, enabling design improvements to be made on both designs. CFD analysis was then executed in order to obtain the lowest drag coefficient number in reducing the air resistance induced by both of the helmet designs, inherently increasing cyclist performance and ensuring competition success

Single class classifier using FMCD based non-metric distance for timber defect detection

In this work, we propose a robust Mahalanobis one class classifier with Fast Minimum Covariance Determinant estimator (MC-FMCD) for species independent timber defect detection. Having known in timber inspection research that there is a lack of defect samples compared to defect-free samples (imbalanced data), this unsupervised approach applies outlier detection concept with no training samples required. We employ a non-segmenting approach where a timber image will be divided into non-overlapping local regions and the statistical texture features will then be extracted from each of the region. The defect detection works by calculating the Mahalanobis distance (MD) between the features and the distribution average estimate. The distance distribution is approximated using chi-square distribution to determine outlier (defects). The approach is further improved by proposing a robust distribution estimator derived from FMCD algorithm which enhances the defect detection performance. The MC-FMCD is found to perform well in detecting various types of defects across various defect ratios and over multiple timber species. However, blue stain evidently shows poor performance consistently across all timber species. Moreover, the MC-FMCD performs significantly better than the classical MD which confirms that using the robust estimator clearly improved the timber defect detection over using the conventional mean as the average estimator

Conventional approach to harmonious coordinated Cadastral Database weakness

The eKadaster system depended solely on the use of coordinated cadastral database known as the National Digital Cadastral Database (NDCDB) with an expected accuracy of ±10cm. Till date, there is an approximately of 7.8 million land parcels and 21.9 million boundary markers in the NDCDB that covers the total area of 132,183 km2. However, the NDCDB accuracy of ±10cm is still not at a satisfactory acceptance level and the adjustment keeps continuing without carrying out verification to the data sources weakness of varying accuracy and input errors. Thus, the foremost important corrective is to ensure the adjustment input files to have the exact value of the sources by further divided the existing adjustment blocks into smaller blocks to verify the input data line by line. A well distributed cadastral control points and latest NDCDB accessibility are also extensively needed to plan and to strengthen the adjustment network. The comparison result of the randomly picked ground truthing points in the field has shown a significant impact on the displacement accuracy that meet the expected tolerance of ±10cm or better after the data input file is cleaned without input error. And to further strengthen the adjustment network in order to make NDCDB accuracy better, the current cadastral control points shall need to tie to a highest accuracy fundamental network

The empirical approach to strengthen coordinated cadastral database accuracy

The coordinated cadastral database in Malaysia is known as National Digital Cadastral Database (NDCDB) with an expected accuracy of ±10cm in rural and ±5cm in urban area. Till date, there are approximately 7.8 million land parcels and 22 million boundary markers in the NDCDB for the whole of Peninsular Malaysia and Federal Territory of Labuan covering total area of 132,183 km2. Since 2010, NDCDB block adjustment has been carried out continuously without giving prime concern to eliminate gross errors in the adjustment's input data. This approach aims to propose a methodology to improve the positional accuracy of the existing NDCDB through utilisation of the current eKadaster application. A comprehensive investigation in the office and field processes has been carried out to prove the efficiency of the methodology introduced. This investigation was focused on the East Coast Rail Link (ECRL) right of way (ROW) survey from Dungun to Besut where displacement of 1 to 6 meters relative to the NDCDB coordinates, as shown in the Land Acquisition (LA) Plan, have been identified. Areas involved are coded as Block T10701, T1100101 and T1100102 which are located in Lubuk Kawah and Pelagat Sub-districts, in the state of Terengganu. Positional accuracy of the NDCDB after adjustment was further verified by comparing the coordinates of randomly picked ground proofing points in the field using Real-Time Kinematic (RTK) observation. This will determine the Root Mean Square Error (RMSE) of the respective NDCDB Block based on actual observations and adjusted coordinate values. With that, it can be concluded that the proposed approach is reasonably practical and capable to improve and strengthen the positional accuracy of existing coordinated cadastral database used in Malaysia