Judul: Analisis Kestabilan Model Infeksi Virus Hepatitis B dengan Pertumbuhan Hepatosit yang Bersifat Logistik
Abstrak: This manuscript discussed a mathematical model to describe the dynamics of population of hepatocytes and hepatitis B virus developed by Eikenberry et al. (2010). This model uses a logistic hepatocytes growth model of hepatitis B virus infection. The stability of the fixed points of the model is determined by basic reproduction number . The value of the basic reproduction number is influenced by the growth and death rate of the virus and the death rate of infected hepatocytes. The results of the analysis show that when healthy hepatocytes population increases to a maximum capacity of the liver. On the other hand, the population of infected hepatocytes as well as virus decreases, which means that the heart is in healthy condition. When population of healthy hepatocytes decreases, while population of infected hepatocytes and virus increase up to some certain points. Hopf bifurcation conditions are satisfied by this model, which means that the system has a limit cycle
Keyword: 

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

Judul: Pembuatan Alat Penentu Warna Tanah Berdasarkan Munsell Soil Color Charts
Abstrak: Pembuatan alat penentu warna tanah memanfaatkan sensor TCS3200 sebagai pendeteksi warna yang telah dikonversi menjadi frekuensi. Alat yang telah dibuat menggunakan sumber cahaya LED berwarna putih dengan jangkauan panjang gelombang 350 nm – 780 nm. Sensor dirancang untuk mengukur nilai intensitas cahaya yang dipantulkan oleh bahan. Keluaran sensor berupa frekuensi yang nilainya proporsional terhadap intensitas cahaya yang diterima. Frekuensi keluaran sensor secara linear diubah menjadi nilai RGB untuk mengurangi riak (noise) pengukuran dan penghematan memori. Data acuan pengelompokan dibuat dalam bentuk database yang berisi notasi warna tanah dan nilai RGB. Penotasian warna didasarkan pada notasi warna yang terdapat di Munsell Soil Color Charts. Klasifikasi sampel uji ke dalam kelompok yang tersedia di database menggunakan metode jarak euclid. Hasil klasifikasi yang terbaik akan ditampilkan di LCD berupa notasi hue value/chroma seperti pada Munsell Soil Color Charts.
Keyword: Munsell, sensor warna, warna tanah