Judul: Temu Kembali Informasi Dokumen XML dengan Pembobotan per Konteks
Abstrak: Various research in the field of information retrieval using XML documents have been conducted.However, those systems didnot consider the structure or tags of the XML documents. To improve the performance of the information retrieval system, we develop an information retrieval system using context weighting. Each weight which is implemented on each context is obtained from the result of correlation between the similarity of each context of the document to the queries and the similarity of the whole document to the queries using linear regression method. The information retrieval system that has been developed using the context weighting is evaluated by using 30 queries. It is found that this experiment decreases the average Mean Average Precision (MAP) value by 1.15% if compared with the information retrieval system without context.
Keyword: XMLtag weighting, information retrieval

Judul: Studi Komparatif Pembobotan Kata untuk Temu Kembali Informasi Dokumen Bahasa Indonesia
Abstrak: One of the classical models of Information Retrieval (IR) systems is the vector space model. Vector in this model represents the weight of terms contained in the documents and queries. A term can be a word, a phrase, or a unit in a document describing the context of the document. Since each term has a different level of importance in the document, weighting is needed. The commonly used weighting method is TF-IDF (Term Frequency Inverse Document Frequency). Previous research indicates that the distribution of term weighting follow the Poisson distribution, hence a method called RIDF (Residual Inverse Document Frequency) was developed. Other weighting methods by considering the query is called Query Term weighting. Both of the latter methods has not been implemented for documents in Indonesian. This research implements the methods TF-IDF, RIDF and Query Term Weighting on search engine for documents in Indonesian. The result of this research is a search engine with an average precision of 63,9%.
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Judul: Adaptation of saccharomyces cerevisiae to cassava acid hydrolisates for bioethanol production.
Abstrak: Acid hydrolisates of cassava contain toxic substances i.e. 3,55 g/l HMF and 0,72 g/l furfural to ethanol producing yeast, Saccharomyces cerevisiae. This study is aiming at screening four strains of S. cerevisiae for their tolerance capacity to that acid hydrolisates. Out of four strains, S. cerevisiae IPBCC 05.548 showed the highest tolerance on the bases of ethanol production. It produced 4,1% (b/v) ethanol. Prior to adaptation, optimum sugar concentration and starter dosage were determined in sequence. Out of 15%, 18%, 20% and 24% concentration. S. cerevisiae IPBCC 05.548 showed the highest ethanol production (4,10% b/v) at 15% of total sugar. Among starter dosage (1, 2 and 3 times of 0,23% of sugar concentration), that were tested on optimal sugar concentration indicated that the twice of dosage was the best for ethanol production. Adaptation was then performed for 72 hours for each cycle. Of the cycles, the 9th cycle (648 hours) showed the highest specific growth rate (0,14g.h-1) as well as ethnol yield (4,13% b/v). Comparison of the adapted strain to unadapted strain proved that the adapted strain produced 30,78% higher ethanol yield than those of unadapted strain.
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