Judul: Latent Semantic Indexing PadaSistem Temu Kembali Dokumen Bahasa Indonesia
Abstrak: Pengindeksan semantik laten merupakan salah satu metode yang berhasil diterapkan pada sistem temu kembali informasi dengan menggunakan dokumen berbahasa Indonesia. Metode yang digunakan adalah dengan memanfaatkan struktur tingkat tinggi implisit dalam asosiasi istilah dengan dokumen (struktur semantik) untuk meningkatkan deteksi dokumen relevan berdasarkan istilah yang ditemukan dalam kueri dalam bahasa Indonesia. Mesin yang dievaluasi menggunakan dokumen pertanian dan dokumen tanaman obat kemudian dibandingkan hasil penyimpanan matriks yang dihasilkan menggunakan Singular Value Decomposition (SVD) dan Semi Discrete Decomposition (SDD). Kemudian nilai k optimum akan ditentukan setelah diperoleh nilai relevan tertinggi pada nilai k tersebut.
Keyword: Information Retrieval, Singular Value Decomposition (SVD), Semi Discrete Decomposition (SDD)

Judul: Mesin Pencari Dokumen Bahasa Indonesia Menggunakan Latent Semantic Indexing dengan Pembobotan Global
Abstrak: Current users tend to like search engine based on semantic of word. This is caused by the existence of synonymy and polysemy problems in the selection of the use of the word. One technique to resolve these issue is Latent Semantic Indexing (LSI). LSI has the ability to find relevant documents even if the word of the query are not written in the document. Currently, TF-IDF term weight algorithm is widely applied in search engines. Xia and Chai (2011) stated that, in a document collection, the term with higher frequency and hypo-dispersion distribution usually contains less information. The purpose of this research is to implement LSI using Singular Value Decomposition (SVD) method with term distribution based global term weight. This research used 1000 Indonesian agricultural documents. The performance of search engine using LSI with term-distribution-based global term weight gave highest average precision around 40.47%. The test result also showed that LSI with term-distribution-based global term weight gives better acuracy than LSI with TF-IDF.
Keyword: 

Judul: Bioelectricity Production from Citrobacter freundii GBH253 and Chlorella pyrenoidosa on Microbial Fuel Cell Anode with Different Carbon Sources
Abstrak: Microbial Fuel Cell (MFC) development has significantly increased from various aspects to get higher and more stable electricity. Developing MFC on microorganism aspect is very important because it plays a crucial role in the MFC system. C. freundii GBH253 is one of the potential exoelectrogen bacterium that could be developed for the MFC system. Integrating C. freundii GBH253 and electricity-producing microalgae, such as C. pyrenoidosa, in the anode of MFC could get more stable and higher electricity. In this study, C. freundii GBH253 and C. pyrenoidosa were coupled to produce electricity from different substrates. C. freundii GBH253 and C. pyrenoidosa were tested on three different media types before being tested on MFC. They were also examined for the co-cultivation test to determine the symbiotic relationship between the two microorganisms. The MFC test was conducted using the Randomized Block Design Factorial and the Tukey test to see significant differences from each treatment. The parameters observed in this study were voltage, power density, Chemical Oxygen Demand (COD), Coulombic Efficiency (CE), pH, and volatile fatty acid (VFA). C. freundii GBH253 cannot grow on microalgae medium, while C. pyrenoidosa could grow on bacterial medium and a mixture of bacterium and microalgae media. The bacterium gained benefit from co-culture with microalgae. In the MFC test, electricity was generated in all treatments, which bacterium + microalgae with acetate treatment could generate power density up to 211,97 mW/m2 and the most stable compared to others. Production of electricity in bacterium-microalgae combination dominated by the bacterium; hence, microalgae still help bacterium by producing electricity and raised the COD value. The pH value of all treatments was higher than the initial pH. Acetate and phenol were VFA produced in all treatments, whereas butyric acid and propionic acid were found in some treatments. Pearson correlation showed that some VFA highly correlated with power density.
Keyword: Chlorella pyrenoidosa, Substrate, Microbial Fuel Cell, Electricity Producing Microalgae, Volatile Fatty Acid, Citrobacter freundii