Judul: Kajian pengeringan lapisan tipis pada Umbi Talas Bogor  (Colocasia esculenta L. Schoot)
Abstrak: Tujuan penelitian ini adalah mengetahui karakteristik fisik, karakteristik termal, dan karakteristik pengeringan lapisan tipis talas bogor (Colocasia esculenta L. Schoot). Perlakuan suhu dan RH yang diberikan pada pengeringan dengan oven masing-masing adalah 35 oC, 45 oC, dan 55 oC dan RH 40.1% sampai 86.5%. Perlakuan suhu tersebut ditentukan setelah melakukan penelitian pendahuluan dengan infrared beberapa kali ulangan dengan variasi suhu 75 oC, 65 oC, dan 55 oC hasilnya kurang efektif. Talas bogor memiliki nilai rata-rata konduktivitas panas 0.5072 W/m K, panas jenis 3.21084 kJ/kg K, massa jenis 1149.5 kg/m3, dan difusivitas panas 1.374 x 10-9 m2/s. Laju penurunan kadar air paling tinggi 0.03633 g H2O/menit. Kecepatan udara pengeringan antara 0.60 m/s sampai 1.10 m/s. Nilai konstanta pengeringan 0.003172/menitpada suhu 35 oC, 0.0043445/menit pada suhu 45 oC, dan 0.006456/menit pada suhu 55 oC., The purpose of the study was to determine the physical and thermal properties, and the thin layer drying characteristics of bogor taro (Colocasia esculenta L. Schoot). Drying temperature treatment is 35 °C, 45 °C, and 55 °C whereas relative humidity (RH) in the drying oven is 40.1% to 86.5%. Temperature is determined after a preliminary research with infrared for multiple replications with temperature variations of 75 °C, 65 °C, and 55 °C, but the result has less effective. Bogor Taro has an average value of thermal conductivity of 0.5072 W/m K, specific heat is 3.21084 kJ/kg K, density is 1149.5 kg/m3, and the thermal diffusivity is 1.374 x 10-9 m2/s. The highest drying rate of the water content is 0.03633 g H2O/minute. The drying air velocity is between 0.60 m/s to 1.10 m/s. Drying constant value is 0.003172/min at 35 oC, 0.0043445/min at a temperature of 45 oC, and 0.006456/min at 55 oC.
Keyword: kadar air, lapisan tipis, umbi talas

Judul: Penanganan Awal dan Pengeringan Umbi Talas (Colocasia esculenta (L.) Schoot) menggunakan Sunbeam Food Dehydrator Tipe DT5600
Abstrak: Drying process had become an effort to process taro corms as the raw material for industry. The main problems of taro corms post-harvesting before drying process were the pre-treatment and how to process the slice of taro corms. The objectives of this research are to study the dehydrator temperature effect and pre-treatment before drying process of taro corms using Sunbeam Food Dehydrator DT5600 (55 ᴼC and 75 ᴼC) to the dried taro corms quality, also to assess the performance of Sunbeam Food Dehydrator DT5600. The slice taro corms had 2 mm thickness. There were four treatments before drying, the first was no treatment as control, the second was blanching treatments of the slice of taro corms within the 7 liters water at temperature of 80 ᴼC for 15 minutes, the third was blanching which followed by the soaking within the 10% concentration of sodium chloride solution, and the fourth was same as third treatment which followed by blanching using 2 g/kg of sodium metabisulphite at temperature of 80 ᴼC for a minute. The result showed that taro which is dried at drying temperature of 75 ᴼC more efficient than that of dried at drying temperature of 55 ᴼC. The drying rate and efficiency of taro drying were 43.84 %bk/jam and 17.38% respectively. Dried taro is categorized into super quality for first and second treatments, first quality for fourth treatments and second quality for third treatments. The pre-treatment of taro drying by using blanching and by the soaking within 10% concentration of sodium chloride solution is recommended to reduce oxalate of dried taro until 81.11%.
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Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model