Abstract. This paper presents a work on a semi-supervised method for topic identification and classification of short texts in the social media, and its application on tweets containing dialogues in a large community of dwellers in a city, written mostly in Indonesian. These dialogues comprise a wealth of information about the city, shared in real-time. We found that despite the high irregularity of the language used, and the scarcity of suitable linguistic resources, a meaningful identification of topics could be performed by clustering the tweets using the K-Means algorithm. The resulting clusters are found to be robust enough to be the basis of a classification. On three grouping schemes derived from the clusters, we get accuracy of 95.52%, 95.51%, and 96.7 using linear SVMs, reflecting the applicability of applying this method for generating topic identification and classification on such data.

IntisariRancang bangun sistem pengukuran resistivitas geolistrik dengan menggunakan sumber arus konstan telah berhasil dibuat dan dianalisis. Sistem pengukuran resistivitas geolistrik terdiri atas rangkaian konverter boost, sumber arus konstan, dan mikrokontroler sebagai sistem kendali proses pengukuran dan akuisisi data resistivitas geolistrik berupa data resistansi. Sistem akuisisi data menggunakan prinsip hukum Ohm, dengan metode geolistrik Wenner. Sumber arus konstan yang berhasil diimplementasikan pada sistem resistivitas geolistrik yakni arus sebesar 0,1 mA bekerja pada resistansi 0,4Ω sampai 2,345 MΩ dan arus 1mA bekerja pada resistansi 0,4Ω hingga 8,53 kΩ. Serta pada pengukuran resistansi dapat terukur dengan baik pada pengukuran resistasi 33Ω hingga 470 kΩ. AbstractDesign of geoelectric resistivity measurement system using a constant current source has been successfully created and analyzed. Geoelectric resistivity measurement system consists of a boost converter circuit, constant current source, and a microcontroller as the control system in the process of measurement and data acquisition resistivity geoelectric form of resistance data. Data acquisition system using the principles of Ohm's law, the geoelectric method of Wenner. In this study, a constant current source that is successfully implemented on geoelectric resistivity that is a current of 0,1 mA work on resistance 0,4 Ω until 2,345 MΩ and a current of 1mA is working on 0,4 Ω resistance to 8,53 kΩ. As well as the resistance measurement can be measured by either the resistance measurement 33 Ω to 470 kΩ.