Judul: Metode Pemilihan Fitur Dokumen Bahasa Indonesia yang Terkelompok pada Mesin Pencari
Abstrak: The large amount of information particularly in the form of large quantities of documents will required a large amount of time and effort to search if done manually. On a vector space, documents are represented by terms. More terms mean higher-dimensional data which makes search more difficult to perform. A large number of documents affects the performance of the search engine to return the documents that are relevant to the user's desires. This study implements correlation coefficient method and compareit with the chi-square method. In this study different levels of accuracy are produced. Correlation coefficient method has an accuracy of 68% while the chi-square method produced an accuracy of 58%
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Judul: Pemilihan Fitur Dokumen Bahasa Indonesia untuk Pengelompokan dengan Metode K-Means
Abstrak: The field of document information retrieval has very diverse and rapidly-growing documents thereforethe need for methods to categorize documents effectively and efficiently increases. Categorizing documents can be performed using clustering techniques. This research uses the K-Means technique, one example of a partitioning clustering algorithm. K-Means is a simple algorithm that aims to get the appropriate grouping. Chi-square feature selection and the IDF were used to obtain the termsused as the unique identifiers of the documents. Clustering results with different feature selection techniques were made forcomparison to get the expected results.The accuracy values obtained for the IDF and the chi-square feature selection for data size 150 using rand index are26%, 75%, respectively.The accuracy values obtained for the IDF and the chi-square feature selection for data size 457 using rand index are31%, 37%, respectively. The accuracy values obtained for the IDF and the chi-square feature selection for data size 150 usingpurity measureare 97%, 96%, respectively. The accuracy values obtained for the IDF and the chi-square feature selection for data size 457 using rand index are 93%, 95%, respectively.
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Judul: Growth, Concentration Chlorophyll-a, and Structure of Macroalgae Gracilaria edulis in the Culture Media Containing Copper
Abstrak: The physiological responses (specific growth rate, concentration of chlorophyll-a, morphological and anatomical structure of the vegetative cells) of the marine macroalga Gracilaria edulis at the different concentrations of copper (0.01 as control, 0.04, 0.06 and 0,5 ppm) delivered continuously for 28 days under controlled laboratory conditions were investigated. Result showed that the degree of copper toxicity depends on both factor the concentration and exposure time. Copper concentration and day of exposure decreased significantly the specific growth rate (SGR) of the Gracilaria edulis but only 0,5 ppm Cu decreased the chlorophyll-a content when compared to control. Of the various physiological end points measured, growth proved to be the most sensitive response than chlorophyll-a with reductions in specific growth rate (SGR). The reason for this could be related to a greater sensitivity of the enzymes involved in growth than those related to chlorophyll-a or a greater energy needs to maintain cellular integrity and metabolic processes under sublethal Cu stress. In all cases, the main effect on vegetative cells were structure changes in cortex and subcortex cells, compared to control, macroalgae exposed to copper showed depigmentation and blending in the lateral branches, heavy staining of the cell wall and severe damage of cell membrane, while the mucilage and the cell walls was densely fibrillar, thick and heavily stained, the cortex cell was clearly vacuolated, the presence of endophytic on the cell wall and endophytic spores in the mucilage. The presence vacuoles should be related to a metal immobilization mechanism, minimizing the Cu toxicity for cells. The epiphytic bacteria can act as a biofilter diminishing the availability of Cu for macroalgae accumulation.
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