Makara Journal of Science
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QUERI GANDA PADA SISTEM TEMU-KEMBALI INFORMASI BERBASIS JARINGAN INFERENSI
No full textThe MultipleQuery of Information Retrieval System Based on Inference Network. The multiple query is a query that combines Boolean and probabilistic query on the information retrieval inference network system, the system consists of two components i.e. a dokument and a query network, they are joined by links between the representation and query concepts. The document network build an inverted belief list and the query network are evaluated by using canonical matrix. The similarity process between representation and query conceps yields a set of relevant document retrieved. The experiment has showed that the use of multiple query formulations will significantly improve the retrieval perfomance, compared to either the Boolean or probabilistic query.Keywords: information retrieval, inverted list, link matrix, canonical matrix, precision-recall table
PENGARUH PELAPISAN PERMUKAAN PARTIKEL SiC DENGAN OKSIDA METAL TERHADAP MODULUS ELASTISITAS KOMPOSIT Al/SiC
No full text The Influence of Coating Oxide Metal on Surface of SiC Particles to Elastic Modulus of Al/SiC Composites. The isotropic composites of Al/SiC is made by powder metallurgy method, the quality of mechanical materials depend on interfacial bonding between matrix (Al) and reinforcement (SiC). The quality of interfacial bonding can influence to elastic modulus of composites which is made by solid process. SiC particles were coated by metal oxide aim to enhance quality interfacial bonding between matrix and reinforcement. These research using three kinds of coating materials, which are Mg oxide, Cu oxide and Al oxide, and these materials were deposited on surface of SiC particles. From three kinds of materials coating Al2O3 is the best to enhance quality interfacial bonding between matrix and reinforce than the others as CuO or MgO. There is Intermetalic phase formatted on CuO coating, and MgO coating have many porous where they can make decrease quality of Al-SiC composites. All of volume fraction of SiC on the Al/SiC composites, which oxide aluminum coating on SiC surface have highest value of elastic modulus than the others metal oxides. Keywords: composites, isotropic, interfacial bonding, matrix, reinforcement, elastic modulu
MELALUI ANALISIS SEISMOGRAM GEMPA-GEMPA BUMI DI SEKITAR INDONESIA PADA STASIUN OBSERVASI UGM
No full textSeismogram Analysis of Earthquakes Around Indonesia In UGM Observational Station: S Velocity Structure. The seismogram comparison between the measured and synthetics seismogram has been carried out in observation station of UGM, where the seismograms are excited by earthquakes that occurred at North Sumatra, Sumbawa, Sunda Strait, around North Celebes and PNG. The ray paths from earthquake's hypocenter to UGM give opportunity to understand the earth structure alongside the front area of subduction zone. The calculation of synthetic seismogram needs input in the form of earth model, the Centroid Moment Tensor (CMT) solution of the earthquake and location of observation station, as well as the relevant date file response of the observation station. Waveform comparison and fitting at surface wave indicate that speed's anomalies in the lithosphere have negative character in front area of subducted zone, but become positive for northern area of subduction zone. By paying attention to waveform of Love surface wave, it is obtained, that this waveform are sensitive to the change of earth crust thickness, while Rayleigh waveform is not sensitive. eterogeneity is not only occurred in the lithosphere, but also in deeper earth layers, until Core Mantle Boundary (CMB). Different corrections are needed to make the fitting at S secondary wave, but also at depth wave and its repetitions. The result of this research shows that the research area, which is located in the front of subduction zone has anomalies at S speed of at deeper earth layers which than the lithosphere. The earth structure as the result of this research differs from the other seismological results, where they used the methods, which are based on inversion of arrival time data of body wave and dispersion analysis on surface wave. Keywords: Subduction zones, love waveform, Moho depths, and S velocity model from upper mantle till CM