Judul: Kajian Peningkatan Kapasitas Proses Co-Composting Blotong dan Abu Ketel
Abstrak: Co-composting at industrial scale can be applied for utilization of filter cake and boiler ash. For applying in industrial scale, study on composting performance in larger capacity was needed. The purpose of this research was to study the performance of composting process in large scale compared with laboratory scale as reference for industrial implementation. The parameters in scale increasing consist of the C/N decrease rate and the effect of aeration for 60 days of composting. Increased composting capacity was done by increasing the capacity of 5 kg to 120 kg. Constant factor in the increase in capacity is congruency geometry, aeration rate and the value of C/N beginning 40. The result showed that composting process at 120 kg scale was not different from 5 kg scale, in which the temperature formed in mesophilic phase, pH level was neutral and optimum moisture content. The rate of decrease C/N was, 1.3675 / day with yield of 68.97% and the estimated time of compost for 20 days. There was no effect of 14 aeration during compost of 120 kg at a rate of decrease C/N. B/C ratio in the analysis of business of industrial compost capacity was 1.42, that means it could be implemented.
Keyword: boiler ash, filter cake, increased capacity, co-composting

Judul: Evaluasi Kinerja Peningkatan Kapasitas Pengomposan dari Campuran Blotong, Bagas, dan Abu Ketel
Abstrak: Composted filter cake, bagasse, and boiler ash on laboratory scaled which used aerated pile method had generated an optimum initial C/N and resulted the best compost quality. Meanwhile in order to be applied directly in industrial scale, the evaluation of laboratory scaled co-composting performance was needed along with increased processing capacity. The aim of this study was to compare larger scale of co-composting performance evaluation with laboratory scale. Capacity enhancement was done by increasing the capacity process from laboratory scaled of 5 kg to 100 kg. The evaluated performance parameters in co-composting were composting rate and the effect of aeration during composting. While constant factors, as same as capacity of 5 kg’s, were reactor geometrical congruency, initial C/N and aeration treatment. Compost mixture had initial C/N value of 50 and active aeration treatment of 0.4 L/min.kg was given in for 1 hour per day in the first week. The result showed that there were no any significant differences of composting rate between 5 kg and 100 kg. Besides, active aeration did not give significant effect to process condition and the composting rate in 100 kg scaled co-composting. Financial analysis of composting was able to bring profits based on the equation of B/C ≥1.
Keyword: evaluation of capacity process, co-composting, C/N, capacity enhancement, aeration

Judul: Pemodelan Nilai Tukar Rupiah Terhadap US Dollar Menggunakan Deret  Waktu Hidden Markov Dua Waktu Sebelumnya
Abstrak: Nilai tukar Rupiah terhadap US Dollar mengalami perubahan setiap waktunya dalam periode yang panjang dan perubahan yang terjadi mungkin terjadi kembali di masa mendatang. Jika penyebab kejadiannya tidak diamati secara langsung dan membentuk suatu rantai Markov maka perubahan nilai tukar Rupiah dapat dimodelkan dengan model deret waktu hidden Markov. Untuk menggambarkan perilaku nilai tukar Rupiah terhadap US Dollar, dalam karya ilmiah ini digunakan model deret waktu hidden Markov dua waktu sebelumnya. Model ini mengasumsikan bahwa nilai tukar Rupiah terhadap US Dollar bergantung pada rantai Markov yang merupakan penyebab kejadian yang tidak diamati dan nilai tukar Rupiah dua waktu sebelumnya.
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