Judul: Optimasi Pengeringan Benih Jagung dengan Perlakuan Prapengeringan dan Suhu Udara Pengeringan
Abstrak: Drying is an important operation in corn seed processing. Long duration of seed drying can reduce seed viability. The high moisture content causes the initiation of seed germination and increase fungal attacks, thus it will loss seed viability. Long duration of seed drying also decreases production capacity and will increase production cost. One of the efforts to increase drying rate is increase air drying temperature. But, the high temperature in seed drying will give risk. It will give effect on chemical composition destruction so it could be decline seed viability. Maintaining seed viability could be done by using predrying treatment. Predrying was done by blowing air using blower machine and it applied before ear corn dried with heated air. Combination between predrying and air drying temperature were the effective treatment to increase drying rate and maintain corn seed viability. The objectives of the research were to increase corn seed drying efficency by develop design of drying system and combine between predrying treatment with air drying temperature to get maximum seed quality. This research was conducted at PT BISI International, Tbk. on June till October 2012. This research consisted of three phases, 1. Drying system design, 2. Corn seed drying optimization, and 3. Economic analysis. The first research consisted of two phases, 1. Mini box dryer assembling, and 2. Mini box dryer testing. Corn seed drying optimization consisted of periods of predrying (0, 12, 24, and 36 hours) and temperature level factor (40, 45, 50, and 55 °C), used randomized complete block design with three replications. Physical and physiological quality were analyzed to find treatment which produced good seeds. Economic analysis were used to find treatment which give highest of B/C Ratio. The result showed that predrying during 36 hours on temperature setting 50 °C was the optimum treatment for corn seed drying, because it had good germination and had highest B/C Ratio.
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Judul: Simulasi Proses Pengeringan Jagung Pipilan dengan Mesin Pengering Surya Tipe Efek Rumah Kaca (ERK)-Hybrid dengan Wadah Silinder
Abstrak: Generally uniformity of moisture content was difficult to be reached due to un-mixed product during drying process. A study on performance of hybrid-green house effect (GHE) solar dryer with rotary drum chamber for shelled corn drying has been conducted. The objectives of this research were: to evaluate performance of hybrid-GHE solar dryer with cylinder type, to develop model to predict temperature, relative of humidity, and decreasing of shelled corn moisture content and to validate the model which developed by the experimental data. The model was constructed based on heat and mass balance. The models were solved by Euler’s finite difference method. Three experiments have been conducted and the results showed that the range of room temperature and relative hummidity were 34.0-41.0 °C and 60.2-76%, respectively. Based on this condition, 1114.1-1304.3 kg mass of shelled corn with the initial moisture content 22.28-24.87% wb. could be dried until to 15.92-17.58% wb. in 8-11 hours. By rotating the cylinder 15 minutes per hour, difference of inside and outside temperature of shelled corn layer was 0-9.8°C and moisture content was 0-2.3% wb. The drying capacity was 118.57-161.76 kg/h. Spesific energy consumption and main cost were 6.03-10.13 MJ/kg and 75.89-124.37 Rupiah/kg, respectively. Total efficiency with solar iradiation and without solar iradiation were 19.88-39.15% and 22.51-46.06%, respectively. The models that had developed has already explain the experiment data. Coefficient of determinant (COD) of model with experiment data for room temperature, relative of humidity, grain temperature, water tank temperature, and moisture content were 0.74, 0.09, 0.35, 0.91 and 0.98, respectively. The absolute percentage deviation (APD) were 1.29%, 5.89%, 1.79%, 3.5% and 0.86%. Simulation for rotating cylinder showed that by continuous rotating had the highest influence for uniformity of temperature and moisture content. The result showed that this treatment had smallest difference of inside and outside temperature and moisture content were 0.05-1.78°C and 0.14-0.56% wb. respectively. Simulation for input changing showed that by using higher mass flow rate was 0.8 kg/second had the best influence for uniformity of temperature. The result showed that this treatment had smallest difference of inside and outside temperature was 0.31-7.81°C and the APD was 3.82%. And by adding 10% iradiation input had the highest influence for uniformity of moisture content. The result showed that this treatment had smallest difference of inside and outside moisture content was 0.14-2.94% wb. and the APD was 1.09%.
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular