A. N. Alias

Algorithm for TSS Mapping Using Satellite Data for Penang Island, Malaysia

The traditional sampling method for environmental monitoring of aerosols is time consuming and expensive. Remote sensing data have been widely used in environmental studies like land cover change, flood observation, environmental pollution monitoring. This study is dealing with obtaining water pollution using Landsat TM data over Penang Strait, Malaysia. With the availability of remotely sensed and in situ data sets the derivable geophysical parameters is sediment (suspended matter) concentration. The proposed algorithm is based on the reflectance model that is a function of the inherent optical properties of water, which can be related to its constituents concentrations. Regression and accuracy analysis is performed using SPSS analysis software. Water samples locations were determined using a handheld GPS. The digital numbers were extracted corresponding to the ground-truth locations for each band was converted into radiance and reflectance and later used for the calibration of the developed algorithm. The efficiency of the present proposed algorithm, in comparison to other forms of algorithm, was also investigated. Based on the values of the correlation coefficient (R) and root-mean-square deviation (RMS), the proposed algorithm is considered superior. The proposed algorithm is considered superior to other tested algorithms based on the values of the correlation coefficient, R=0.94 and root-mean-square error, RMS=5 mg/l. The calibrated TSS algorithm was used to generate the water quality map. The TSS map was color-coded and geometrically corrected for visual interpretation.

Current crowding effect in lateral and vertical LED configurations: 3D simulation and characterisation

Current crowding is one of the major issue that impedes the development of the efficient GaN-based high power light emitting diode (LED). Generally, there are two types of LED configurations, namely lateral configuration and vertical configuration needed to be experimentally fabricated to study the effects of current crowding on LED electrical and optical performance. In order to minimize the cost and time required to examine the full effect of the current crowding problem inside the devices, an identical free standing active LED layers with same contact size, material and thickness for both configurations are simulated by using ISE TCAD. In this work, we found that vertical LED configuration exhibits better electrical and optical performance by 20% and 21% respectively as compared to the lateral LED. The vertical configuration exhibits a better performance due to reduced series resistance, improved current spreading and better hear dissipation.

Determination of cloud and aerosol layers using CALIPSO and image processing

The height of cloud and aerosol layers in the atmosphere is believed to affect climate change and air pollution because both of them have important direct effects on the radiation balance of the earth. In this paper, we study the ability of Cloud Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) data to detect, locate and distinguish between cloud and aerosol layers in the atmosphere over Peninsula Malaysia. We also used image processing technique to differentiate between cloud and aerosol layers from the CALIPSO images. The cloud and aerosol layers mostly are seen at troposphere (>10 km) and lower stratosphere (>15km). The results shows that CALIPSO can be used to determine cloud and aerosol layers and image processing technique has successfully distinguished them in the atmosphere.

An initial assessment of the CALIPSO lidar data on stratospheric aerosol backscatter coefficients over peninsular Malaysia

Remote sensing using the satellite borne LIDAR systems are currently providing new features for global atmospheric sensing from space. The LIDAR on board the Cloud Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) satellite is currently obtaining global aerosol and cloud measurements from space since launched on April 28, 2006. The CALIPSO satellite carries a polarization-sensitive LIDAR system that records backscatter measurements at 532 nm and 1064 nm. In this study, we investigated the stratospheric aerosol backscatter coefficients over Peninsular Malaysia. An initial result of actual data supports that the CALIPSO LIDAR data exhibits sensitivity to the presence of stratospheric aerosol in this study area.

Aerosol Characterization over Penang, Malaysia Using Aerosol Robotic Network (AERONET)

Ground-based solar photometer measurements were utilized in the ambiance of Universiti Sains Malaysia (USM) Penang and Universiti Teknologi MARA (UiTM) Penang during September-November 2013 with a specific end goal to portray the characteristics of the local atmospheric environment. This both sites were established as being component of the collaborative work of the Seven South East Asian Studies (7SEAS) regional aerosol measurement project. This study concentrates on the Angstrom exponent (α), that is the gradient of the logarithm of the aerosol optical depth (AOD) against the logarithm of the wavelength as well as being commonly used to characterize the wavelength reliance of AOD and to furnish some critical data on the aerosol size distribution. In most situations fine mode aerosols appear to be the predominant category with marginally substantial contributions of coarse mode particles resulting from the particle growing, blending processes with other aerosol types, precipitation factors and relative distance to the seashore.

Machining performance of zirconia toughened alumina reinforced with MgO in dry end milling of AISI 1018 steel

The main goal of this work is to investigate the performance of zirconia toughened alumina (ZTA) and ZTA reinforced with magnesium oxide (MgO) used as cutting insert in end milling of AISI 1018 steel with hardness of 27 HRC. Performances of the cutting insert were compared according to tool life and surface finish of workpiece. Insert flank wear that indicates tool life was studied carefully using Optical 3D Surface Metrology. Surface roughness values were evaluated using Surftest Sufrcom 130A. Both of the cutting inserts failed to exhibit good performance in end milling operation. However, wear condition and magnitude of the ZTA reinforced with MgO insert was slightly better than ZTA insert. Addition of MgO may increase wear resistance.

LIDAR and image processing of aerosol-cloud vertical profile

Light Detection and Ranging (LIDAR) was on board a satellite named CALIPSO which is one of the satellites flying in synchronized with other A- Train satellites. Backscattering profiles from LIDAR can determine the height and profiles of the clouds. Air pollution and other particulate matter trends in the atmosphere will affect the growth of clouds. This paper is focusing in analysing LIDAR and remote sensing data using image processing technique. Findings of this paper signify a weighty progress in the understanding of the processes with significant effects for both climate science and sustainable development.

Modeling of aerosol and cloud optical depth

We have applied regression model together with statistical test, Pearson Correlation, to examine the relationships between aerosol optical depth (AOD), cloud optical depth (COD) and water vapor retrieved by Moderate Resolution Imaging Spectrometer (MODIS) in 2009 over Malaysia. It is shown that the relationship between water vapor in clear sky and AOD mean showed the highest significant compared to the others. Pearson Correlation showed that AOD and Water Vapor (Clear sky) have positive correlation but COD and water vapor (cloudy) have negative correlation, which both have significant correlation (p<0.01). Such regression model and correlation play an essential part in order to quantify the contributions in influencing climate change and global warming. However, analysis of the complex connection of AOD, COD and water vapor should be made with great care and further work is needed.

Atmospheric transmittance modeling in urban and rural area

The properties of atmospheric spectral transmittance over Malaysia are studied using MODTRAN. The atmospheric propagation is being treated as electromagnetic radiation which ranged from 100–50000 cm−1 with a spectral resolution of 1 cm−1. Based on the study area factor, tropical model is being used in this study. The results demonstrated the characteristics of atmospheric transmittance obtained using MODTRAN which showed the absorption and absorptive properties in the atmospheric layer.

Water quality mapping using Landsat TM imagery

Environmental monitoring through the method of traditional ship sampling is time consuming and requires a high survey cost. The objective of this study is to evaluate the feasibility of Landsat TM imagery for total suspended solids (TSS) mapping using a newly developed algorithm over Penang Island. The study area is the seawater region around Penang Island, Malaysia. Water samples were collected during a 3-hour period simultaneously with the satellite image acquisition and later analyzed in the laboratory above the study area. The samples locations were determined using a handheld GPS. The satellite image was geometrically corrected using the second order polynomial transformation. The satellite image also was atmospheric corrected by using ATCOR2 image processing software. The digital numbers for each band corresponding to the sea-truth locations were extracted and then converted into reflectance values for calibration of the water quality algorithm. The proposed algorithm is based on the reflectance model that is a function of the inherent optical properties of water, which can be related to its constituents concentrations. The generated algorithm was developed for three visible wavelenghts, red, green and blue for this study. Results indicate that the proposed developed algorithm was superior based on the correlation coefficient (R) and root-mean-square deviation (RMS) values. Finally the proposed algorithm was used for TSS mapping at Penang Island, Malaysia. The generated TSS map was colour-coded for visual interpretation and image smoothing was performed on the map to remove random noise. This preliminary study has produced a promising result. This study indicates that the empirical algorithm is suitable for TSS mapping around Penang Island by using satellite Landsat TM data.