Climate variability has become a matter worth our attention as this issue has unveiled to the extreme water-related
disasters such as flood and drought. Increments in heavy precipitation have happened over the past century and future
climate scenarios show that it may alter the recurrence, timing, force, and length of these occasions. Satellite
precipitation products (SPPs) could be used as representation of precipitation over a large region. This could be useful
for the monitoring of the precipitation pattern as well as extreme events. Nevertheless, application of these products in
monitoring extreme precipitation is still limited because insufficiency of quality assessment. This study aims to evaluate
the performance of the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA)
3B42V7 product in capturing the behavior of extreme precipitation events over Peninsular Malaysia from 2000 to 2015.
Four extreme precipitation indices, in two general categories of absolute threshold (R10mm, R20mm and R50mm) and
maximum (Rx1d) indices that recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI)
were used. General evaluation has shown that the TRMM 3B42V7 product performed good on the measurements of
monthly and annual precipitation. In the respect of extreme precipitation measurements, weak to moderate positive
correlations were found between the TRMM 3B42 product and rain gauges over Peninsular Malaysia. The TRMM
3B42V7 product overestimated the R10mm and R20mm indices, while an underestimation was found for the R50mm
and Rx1d indices.
Drought is one of the most hazardous natural disasters for human beings and the environment. Using only rain gauge is
insufficient to monitor the drought pattern effectively as it impacts large areas. This situation is more critical on small
island countries, with limited rain gauges for monitoring drought pattern over the ocean regions. This study aims to
assess the capability of Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA)
3B43 product in monitoring drought in Singapore from 1998 to 2014. The Standardized Precipitation Index (SPI) at
various time-scales is used for identifying drought patterns. Results show moderate to good correlations between TMPA-
3B43 and rain gauges in the SPI estimations. Besides that, TMPA-3B43 exhibits a similar temporal drought behavior as
the rain gauges. These findings indicate the TMPA 3B43 product as a very useful tool to study drought pattern over
Singapore.
Mangroves are known as salt-tolerant evergreen forests, whereas its create land-ocean interface ecosystems. Besides,
mangroves bring direct and indirect benefits to human activities and play a major role as significant habitat for
sustaining biodiversity. However, mangrove ecosystem study based on the mangrove species are very crucial to get a
better understanding of their characteristics and ways to separate among them. In this paper, discriminant functions
obtained using statistical approach were used to generate the score range for six mangrove species (Rhizophora
apiculata, Acrostichum aurem, Acrostichum speciosum, Acanthus ilicifolius, Ceriops tagal and Sonneratia ovata) in
Matang Mangrove Forest Reserve (MMFR), Perak. With the computation of score range for each species, the fraction of
the species can be determined using the proposed algorithm. The results indicate that by using 11 discriminant functions
out of 16 are more effective to separate the mangrove species as the higher accuracy was obtained. Overall, the
determination of leaf sample’s species is chosen base on the highest fraction measured among the six mangrove species.
The obtained accuracy for mangrove species using statistical approach is low since it is impossible to successfully
separate all the mangrove species in leaf level using their inherent reflectance properties. However, the obtained
accuracy results are satisfactory and able to discriminate the examined mangrove species at species scale.
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.
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.
Ozone (O3) is unique among pollutants because it is not emitted directly into the air, and its results from complex chemical reactions in the atmosphere. O3 can bring different effects for all the living on earth (either harm or protect), depending on where O3 resides. This is the main reason why O3 is such a serious environmental problem that is difficult to control and predict. The objective of this paper is to analyze the variations of total column O3 measured by Brewer O3 spectrophotometer over Global Atmosphere Watch Station (GAW) regional station, which is located at southwest of Peninsular Malaysia, Petaling Jaya. Total column O3 observations in Petaling Jaya are studied for the period January 2008 to December 2008. Ozone shows seasonal variation with maximum (276.8 DU in May 2008) during pre-monsoon season and minimum (246.8 DU in January 2008) during northeast monsoon season. In addition, the monthly O3 maps for the year of 2008 were obtained from the NASA-operated Giovanni portal to overview the distribution of total column O3 in Peninsular Malaysia. For the upcoming studies, validation of ground measurements with satellite O3 data and study of tropospheric O3 over the study area is recommended.
This research article proposes an alternative method to measure the discoloration or the color changes of EBT3 films due
to exposure by solar ultraviolet (UV A+B) dose. Common methods to measure the color changes of EBT3 are through
imaging technique measured by flatbed scanner and through absorbance spectroscopy measured by visible spectrometer.
The research presented in this article measure the color changes of EBT3 through simplified optical system using the
combination of light emitting diode (LED) as the light source and photodiode as the detector. In this research, 50 pieces
of Gafchromic EBT3 films were prepared with the dimension of 3 cm x 2 cm. Color of the films changed from light
green to dark green based on the total accumulated UV dose (mJ/cm2) by each film that depends on the duration of
exposure, irradiance level (mW/cm2) and condition of the sky. The exposed films were then taken to the laboratory for its
color measurement using absorbance spectroscopy technique and using newly developed simplified optical instrument
using LED-photodiode. Results from spectroscopy technique indicate that wavelength within red region exhibit better
response in term of linearity and responsivity towards the colors of EBT3 films. Wavelength of 626 nm was then
selected as the peak emission wavelength for LED-photodiode absorbance system. UV dose measurement using LEDphotodiode
system produced good result with coefficient of determination, R2 of 0.97 and root mean square of error,
RMSE of 431.82 mJ/cm2 while comparatively, similar wavelength but analyzed from spectroscopy dataset produced R2
of 0.988 and RMSE of 268.94 mJ/cm2.
The major issues concerning to food products are related to its authenticity. Honey is one of the common food products that suffer from adulteration, mainly due to its constant high market demand and price. Several studies on the authenticity detection have been done mainly on honey from genus Apis (GA), but less research has been conducted on Stingless Bee Honey (SBH) even the market demand for this food product is increasing, particularly in Malaysia due to its possible health benefits. Thus, identification of unadulterated and authenticity of honey is a very key issue for products processors, retailers, consumers and regulatory authorities. There is an increasing demand for appropriate instruments and methods to shield consumers against fraud and to guarantee a fair competition between honey producers. The study presented in this paper shows the effect of diluting pure honey from both genus Apis and Stingless Bee towards its physicochemical attributes (i.e. soluble solids content and pH) and VIS-NIR spectral absorbance features.
In this paper, the simulation and design of a waveguide for water turbidity sensing are presented. The structure of the proposed sensor uses a 2x2 array of multimode interference (MMI) coupler based on micro graphene waveguide for high sensitivity. The beam propagation method (BPM) are used to efficiently design the sensor structure. The structure is consist of an array of two by two elements of sensors. Each element has three sections of single mode for field input tapered to MMI as the main core sensor without cladding which is graphene based material, and then a single mode fiber as an output. In this configuration MMI responses to any change in the environment. We validate and present the results by implementing the design on a set of sucrose solution and showing how these samples lead to a sensitivity change in the sensor based on the MMI structures. Overall results, the 3D design has a feasible and effective sensing by drawing topographical distribution of suspended particles in the water.
In this paper, we study the self-phase modulation on a sub-micro graphene waveguide to show the nonlinear optical properties of graphene. Self-modulation is one of the most popular nonlinear effects that has been observed due to selfinfluence of a mode propagation in third-order materials. This effects is capable to demonstrate the nonlinearity based the structure. Our study is aimed to show the appearance of SPM in considered waveguide as a common effect of nonlinear refraction to proof the capability of graphen on apply the based waveguide in nonlinear regime to access the desired parameters such as dimension and insertion power. An interest aspect is placed in this simulation may be conversion step-index to grade-index due to change from linear to the nonlinear that causes high confinement of light in waveguide.
Among all the greenhouse gases, methane is the most dynamic and abundant greenhouse gas in the atmosphere. The global concentrations of atmospheric methane has increased more than doubled since pre-industrial times, with a current globally-averaged mixing ratio of ~ 1750 ppbv. Due to its high growth rate, methane brings significant effects on climate and atmospheric chemistry. There has a significant gap for variables between anthropogenic and natural sources and sinks of methane. Satellite observation of methane has been identified that it can provide the precise and accurate data globally, which sensitive to the small regional biases. We present measurements from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) included on the European environmental satellite ENVISAT, launched on 1st of March 2002. Main objective of this study is to examine the methane distribution over Peninsular Malaysia using SCIAMACHY level-3 data. They are derived from the near-infrared nadir observations of the SCIAMACHY at the University of Bremen through scientific WFM-DOAS retrieval algorithm version 2.0.2.Maps of time averaged (yearly, tri-monthly) methane was generated and analyzed over Peninsular Malaysia for the year 2003 using PCI Geomatica 10.3 image processing software. The maps show dry-air column averaged mixing ratios of methane (denoted XCH4). It was retrieved using the interpolation technique. The concentration changes within boundary layer at all altitude levels are equally sensitive through the SCIAMACHY near-infrared nadir observations. Hence, we can make observation of methane at surface source region. The results successfully identify the area with highest and lowest concentration of methane at Peninsular Malaysia using SCIAMACHY data. Therefore, the study is suitable to examine the distribution of methane at tropical region.
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