Judul: Analisis Kestabilan pada Model Epidemik SIR dengan Waktu Diskret.
Abstrak: Model epidemik merupakan model matematika yang digunakan untuk menganalisis perilaku penyebaran penyakit menular. Salah satu model epidemik adalah model epidemik SIR. Model epidemik SIR terdiri atas tiga subpopulasi, yaitu individu rentan 𝑆���� (susceptible), individu terinfeksi 𝐼���� (infected), dan individu yang telah sembuh dan kebal terhadap penyakit 𝑅���� (recovered). Model epidemik SIR yang dibahas adalah model epidemik SIR dengan waktu diskret yang dijelaskan oleh persamaan beda. Pada model tersebut diperoleh titik tetap beserta kestabilannya. Simulasi numerik dilakukan untuk menunjukkan perilaku dinamis pada model tersebut. Hasil simulasi menunjukkan bahwa pemilihan nilai parameter ℎ, yaitu ukuran langkah, akan mempengaruhi sistem. Jika nilai ℎ dinaikkan, maka terjadi perubahan pada jumlah titik tetapnya, semakin besar nilai ℎ maka akan terjadi perilaku chaos atau kekacauan. Perubahan pada nilai parameter selain ℎ tidak mempengaruhi kestabilan pada sistem, sehingga bertambahnya titik tetap hanya dipengaruhi oleh parameter ℎ.
Keyword: SIR, diskret, titik tetap, kestabilan, kekacauan

Judul: Analisis Kestabilan pada Model Epidemik SIR dengan Waktu Diskret
Abstrak: Model epidemik merupakan model matematika yang digunakan untuk menganalisis perilaku penyebaran penyakit menular. Salah satu model epidemik adalah model epidemik SIR. .. dst
Keyword: SIR, diskret, titik tetap, kestabilan, kekacauan

Judul: Hybrid solar cells of ZnO nanoparticles/chlorophyll was modified metal ions (Zn2+ and Cu2+ )
Abstrak: Zinc Oxide (ZnO) is a n-type semiconductor with a wide the energy band (Band Gap) is 3.37 eV at room temperature and 3.34 eV at low temperature with a large exiton binding energy is 60 meV. ZnO has been synthesized by hydrothermal method, resulting in a decrease in particle size over the duration of the hydrothermal changes. Crystallographic structure of ZnO were characterized using XRD, has shown the characteristic pattern of a hexagonal wurtzite structure, the crystallite size increases to changes in particle size. Changes in particle size has also led to a change in the absorption peak of ZnO as has been demonstrated posted under test using the optical properties of UV-Vis spectrophotometer. Changes of this uptake has also led to changes in the energy band gap, which increases its band gap energy of the particle size. In electronic applications, especially in solar cells. Chlorophyll is considered less effective, because of their very nature are easily degraded as a result of several reactions which are acid, lighting and temperature. The results of the stability test using a halogen lamp 34 W/m2 for 5 hours, that the substitution of chlorophyll with metal ions Zn2+ and Cu2+ has been shown to form more stable than natural chlorophyll. The characterization of the optical properties, the combination of ZnO / chlorophyll in the form of hybrid films has led to a shift in the absorption region of ZnO becomes more widely from the UV to Visible. ZnO/chlorophyll has absorption range of 350-515 nm, ZnO / Zn-feofitin 332-401 nm and 332-632 nm for Cu-feofitin. The combination of ZnO/chlorophyll and CuSCN as a solid electrolite in hybrid solar cell, a modified chlorophyll with metal ions Zn2+ and Cu2+ has been shown to form a more stable I-V curve. It is characterized by its fill factor value greater than natural chlorophyll. Nevertheless, solar cells with natural chlorophyll has been able to produce higher efficiency values of chlorophyll were substituted.
Keyword: Hydrothermal, ZnO/Chlorophyll modified, Hybrid Solar Cell