It has been already made, calibrated and tested a geometry normalized electromagnetic system (GNES) for metal defect examination. The GNES has an automatic data acquisition system which supporting the efficiency and accuracy of the measurement. The data will be displayed on the computer monitor as a graphic display then saved automatically in the Microsoft Excel format. The transmitter will transmit the frequency pair (FP) signals i.e. 112.5 Hz and 337.5 Hz; 112.5 Hz and 1012.5 Hz; 112.5 Hz and 3037.5 Hz; 337.5 Hz and 1012.5 Hz; 337.5 Hz and 3037.5 Hz. Simultaneous transmissions of two electromagnetic waves without distortions by the transmitter will induce an eddy current in the metal. This current, in turn, will produce secondary electromagnetic fields which are measured by the receiver together with the primary fields. Measurement of percent change of a vertical component of the fields will give the percent response caused by the metal or the defect. The response examinations were performed by the models with various type of defect for the master curves. The materials of samples as a plate were using Aluminum, Brass, and Copper. The more of the defects is the more reduction of the eddy current response. The defect contrasts were tended to decrease when the more depth of the defect position. The magnitude and phase of the eddy currents will affect the loading on the coil thus its impedance. The defect must interrupt the surface eddy current flow to be detected. Defect lying parallel to the current path will not cause any significant interruption and may not be detected. The main factors which affect the eddy current response are metal conductivity, permeability, frequency, and geometry.
Aceh had been the focus of an unprecedented international rehabilitation effort in response to the extreme SumatraAndaman earthquake and tsunami disaster on December 24, 2004. During this period, most researchers have contributed to better understanding what happened in the past, and what going to happen in the future. This paper is related to the environmental impact assessment of post-disaster recovery and reconstructions in Banda Aceh city of Indonesia. The indicators are based on the use of the moderate spatial resolution optical satellite sensor by assessing the impacts of land use and land cover change (LULC) on land surface temperature (LST). LULC classification and LST were derived and estimated utilizing visible and thermal infrared data of the Landsat-5 TM + Landsat 8 OLI within the period 2000 and 2015. The surface temperature-vegetation index space of LULC was established to investigate the impacts of land changes over LST sensitivity. The result demonstrated that the post-disaster recovery and reconstruction has had a significant impact to the LULC in Banda Aceh and its fringes. Dramatic LULC in Banda Aceh significantly increases the LST, the temporal trend of pixels space migrated from the dense vegetation-low temperature condition to the less dense vegetation-high temperature condition.
The Kelantan estuary, located in the northeastern part of Peninsular Malaysia, is characterized by high levels of
suspended sediments. Kuala Besar is the estuary of the river directly opposite South China Sea. Spectral reflectance (Rr)
and transparency measurements were carried out in the Kelantan estuary. The objective in this study is to establish
empirical relationships between spectral remote sensing reflectance in ALOS satellite imagery and water column
transparency, i.e. nephelometric turbidity unit (NTU) and Secchi disc depth (SDD) through these numerous in situ
measurements. We detected that remote sensing reflectance are linear and power regression functions against NTU and SDD. The results of this sampling show that the wavelengths range from 500-620 nm is the most suitable band for
measuring water column transparency. The calibrated reflectance of ALOS AVNIR-2 bands was also regressed against
NTU and SDD field data to derive two empirical equations for water transparency estimation. These equations were
calculated using ALOS images data on June 12, 2010. The result obtained indicated that reliable estimates of turbidity
and transparency values for the Kelantan Estuary, Malaysia, could be retrieved using this method.
This paper presents the utilities of remote sensing technique for water quality assessment in Kelantan Delta, Malaysia. Remote sensing is one of the effective methods for water quality monitoring through image analysis of study area. Spectral reflectance signatures of Kelantan Delta were measured from 20 stations using ASD Handheld
spectroradiometer from regions with different turbidity level. Water samples collected from these stations were taken to the laboratory for measure turbidity in Nephelometric Turbidity Unit (NTU). The objective of this study is to examine the potential of ALOS on Japanese Earth Observing Satellite (JEOS) for assessing water quality in Kelantan Delta. There is a large correlation between NTU and the in-situ reflectance at 500 - 620 nm (maximum spectra band between 300 and 1100 nm) is shown by multiple linier regression model, resulting from increasing of turbidity levels, was developed and applied to ALOS band 2 and band 3 (0.42-069 nm). A simple atmospheric correction, based on darkest pixel technique was performed in this study. The ALOS data provides accurate estimates of the mean water quality (R2 = 0.95 and RMSE = 2.26 NTU). The result acquired is reliable to estimate of water quality values for the Kelantan Delta and its implication for future operation.