| Judul | Abstract | Halaman |
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| Wave Propagation over a Submerged Bar | Based on small amplitude water theory we determine an exact solution for the amplitude of the reflected and transmitted waves produced when a monochromatic wave hits a submerged bar, a result of importance in coastal engineering. We compare the results obtained with results previously obtained in the long wave length limit and other numerical results. Using the results obtained we determine the optimal width or the bar of prescribed depth. | 81-90 |
| Detecting Rice Phenology in Paddy Fields with Complex Cropping Pattern Using Time Series MODIS Data | Monitoring paddy rice phenology and cropping schedules over wide areas is essential for many applications. Remote sensing provides a viable means to meet the requirement of improved regional-scale data set of paddy rice fields, such as phenological stages. A number of methods have been developed for detecting seasonal vegetation changes by using satellite images. Development of such methods to paddy fields with complex cropping pattern is still challenging. In this study, we developed a method for remotely determining phenological stages of paddy rice that uses time series of two vegetation indices (EVI and LSWI) obtained from MODIS data. We ran the algorithm to determine the planting date, heading date, and harvesting date of paddy rice in 5 districts of West Java Province, using the 8-day composite MODIS Surface Reflectance products (500-m spatial resolution) in 2004. Estimated harvesting dates were then used to calculate paddy rice harvested area. We validated the performance of the method against statistical data in 13 subdistricts. The root mean square errors of the estimated paddy rice harvested area against the statistical data were: 851 Ha for monthly data, 1227 Ha for quarterly data, and 2433 Ha for yearly data. Subdistrict-level comparisons of paddy rice harvested area between the MODIS estimation and statistical data showed moderate correlation, with coefficient of determination (r2) 0.6, 0.7, and 0.6 for monthly, quarterly and yearly data, respectively. The results of this study indicated that the MODIS-based paddy rice phenological detection algorithm could potentially be applied at large spatial scales to monitor paddy rice agriculture on a timely and frequent basis. | 91-106 |
| Observed Intraseasonal Oceanic Variations in the Eastern Equatorial Indian Ocean and in the Outflow Straits of the Indonesian Throughflow | The observed currents in the eastern equatorial Indian Ocean and in the outflow straits of the Indonesian Throughflow (ITF) are shown to have significant intraseasonal variations and coherency during January 2004 – November 2006. The wavelet analysis between the eastern equatorial Indian Ocean and the ITF straits demonstrates significant intraseasonal coherency for the observed current at 50m depth. At 150m depth, the intraseasonal coherency only occurs between the observed currents in the eastern equatorial Indian Ocean and in the Lombok and Ombai Straits. On the other hand, at 350m depth the intraseasonal coherency is only found between the eastern equatorial Indian Ocean and the Ombai Strait. This intraseasonal coherency is associated with the wind-forced equatorial Kelvin waves which propagate eastward along the equatorial and coastal wave guides. Near-surface intraseasonal variations are associated with the first baroclinic mode with typical phase speed of 2.91 ± 0.46 m s-1, while the deeper layer intraseasonal variations are associated with the second baroclinic mode with typical phase speed of 1.59 ± 0.18 m s-1. Moreover, the lag correlations between the zonal winds and the observed currents at the ITF straits further demonstrate the source of intraseasonal variations in the ITF. | 107-126 |
| Thermal Structure of Subducting Slab along the Java Arc and Its Significance to the Volcanoes Distribution | Java Island has a unique tectonic features and one of it is the pattern of the volcano distribution along the island. The volcano pattern occurrence might be connected to the deeper process of geodynamic. Hence, thermal structure modeling is employed to find any association between the subducting plate and the tectonic of the overriding plate. Thermal structure of a subducting plate depends on the age of the lithosphere and the dip of the subduction. With the lithospheric age increases from west to east of Java, varies from about 90 my to 120 my old, there are dissimilarities in thermal structure models. The comparison with volcanoes positions shows that differences of thermal structure might have associated to variation in the formation of volcanoes in Java Island. | 127-134 |
| Integral Operator Defined by k-th Hadamard Product | We introduce an integral operator on the class A of analytic functions in the unit disk involving k ƒ{ th Hadamard product (convolution) corresponding to the differential operator defined recently by Al-Shaqsi and Darus. New classes containing this operator are studied. Characterization and other properties of these classes are studied. Moreover, subordination and superordination results involving this operator are obtained. | 135-152 |
| Quivers of Bound Path Algebras and Bound Path Coalgebras | Algebras and coalgebras can be represented as quiver (directed graph), and from quiver we can construct algebras and coalgebras called path algebras and path coalgebras. In this paper we show that the quiver of a bound path coalgebra (resp. algebra) is the dual quiver of its bound path algebra (resp. coalgebra). | 153-162 |
| GIS Based Landslide Hazard Mapping Prediction in Ulu Klang, Malaysia | Since 1993, a number of landslides have been reported in Ulu Klang, Malaysia. These landslides caused fatalities and economic losses. Most of these landslides occurred in man-made slopes. Geographical Information System (GIS) is proposed to be used as the based machine for the production of landslide hazard map. This study highlights the area based landslide hazard assessment at Ulu Klang area using GIS application in order to help the engineer or the town planner to identify the most suitable development area besides predicting the potential landslide hazard area. Four main factors that influence of landslide occurrence were chosen include slope gradient aspect, geology, surface cover/land used and precipitation distribution. Landslide hazardous areas were analyzed and mapped using GIS application and produced a hazard map with five different indexes (i.e., very low, low, medium, high and very high hazard). The results of the analysis were verified using the landslide location data. The result showed that the model was very suitable in predicting landslide hazard and generating landslide hazard maps. | 163-178 |
