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: Metode Pembobotan Kata Berbasis Sebaran untuk Temu Kembali Informasi Dokumen Bahasa Indonesia
Abstrak: Term weight algorithm plays an important role in the process of document searching, which is greatly influenced by the precision and recall results of the Search Engine. Currently, TF-IDF term weight algorithm is widely applied in language models to build the search engine systems. Since term frequency is not the only discriminator which is necessary to be considered in term weighting and make each weight suitable to indicate the term’s importance, term weighting algorithm based on term distribution has been developed. In a single document, a term with higher frequency and closer to hypo-dispersion distribution usually contains more semantic information and should be given higher weight. One the other hand, in collection of documents, the term with higher frequency and hypo-dispersion distribution usually contains less information. This research implements term weight based on term distribution, with Local Term Weight Algorithm and Global Term Weight Algorithm for the documents in Indonesian Language. The result of this research is a Search Engine with an average precision of 84.8%.
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Judul: Hybrid solar cells of ZnO nanoparticles/chlorophyll was modified metal ions (Zn2+ and Cu2+ )
Abstrak: Zinc Oxide (ZnO) is a n-type semiconductor with a wide the energy band (Band Gap) is 3.37 eV at room temperature and 3.34 eV at low temperature with a large exiton binding energy is 60 meV. ZnO has been synthesized by hydrothermal method, resulting in a decrease in particle size over the duration of the hydrothermal changes. Crystallographic structure of ZnO were characterized using XRD, has shown the characteristic pattern of a hexagonal wurtzite structure, the crystallite size increases to changes in particle size. Changes in particle size has also led to a change in the absorption peak of ZnO as has been demonstrated posted under test using the optical properties of UV-Vis spectrophotometer. Changes of this uptake has also led to changes in the energy band gap, which increases its band gap energy of the particle size. In electronic applications, especially in solar cells. Chlorophyll is considered less effective, because of their very nature are easily degraded as a result of several reactions which are acid, lighting and temperature. The results of the stability test using a halogen lamp 34 W/m2 for 5 hours, that the substitution of chlorophyll with metal ions Zn2+ and Cu2+ has been shown to form more stable than natural chlorophyll. The characterization of the optical properties, the combination of ZnO / chlorophyll in the form of hybrid films has led to a shift in the absorption region of ZnO becomes more widely from the UV to Visible. ZnO/chlorophyll has absorption range of 350-515 nm, ZnO / Zn-feofitin 332-401 nm and 332-632 nm for Cu-feofitin. The combination of ZnO/chlorophyll and CuSCN as a solid electrolite in hybrid solar cell, a modified chlorophyll with metal ions Zn2+ and Cu2+ has been shown to form a more stable I-V curve. It is characterized by its fill factor value greater than natural chlorophyll. Nevertheless, solar cells with natural chlorophyll has been able to produce higher efficiency values of chlorophyll were substituted.
Keyword: Hydrothermal, ZnO/Chlorophyll modified, Hybrid Solar Cell