Judul: Agent-Based Modeling of SARS-CoV-2 Virus Infection Dynamics and Vaccination Effects
Abstrak: Salah satu virus yang menjadi penyebab pandemi COVID-19 dalam beberapa tahun terakhir yaitu SARS-CoV-2. Penelitian ini memodelkan interaksi antibodi, sel darah putih, sel epitel, vaksin COVID-19 dan virus SARS-CoV-2 menggunakan pemodelan berbasis agen. Pemodelan berbasis agen digunakan untuk simulasi suatu sistem yang kompleks sesuai aturan-aturan dalam fenomena nyata yang terjadi di alam. Seluruh agen memiliki aturan yang didasarkan dari karakteristik dan perilaku setiap agen ketika berinteraksi didalam tubuh. Simulasi dilakukan dengan enam skenario dan satu skenario tambahan. Setiap skenario dibedakan dengan waktu ketika virus mulai menginfeksi. Hasil simulasi menunjukkan bahwa virus yang menginfeksi setelah pemberian vaksin dosis lanjutan (booster) dapat di tangani antibodi dengan optimal dibandingkan sebelum pemberian vaksin primer dosis lengkap. Pada simulasi jangka panjang untuk skenario tambahan menunjukkan bahwa diperlukan vaksin dosis keempat untuk mempertahankan efektivitas vaksin. Virus yang berinteraksi dengan sel epitel dan melakukan infeksi-replikasi akan meningkatkan nilai entropi. Nilai entropi akan menurun apabila virus dapat ditangani dengan baik oleh antibodi., One of the viruses that caused the COVID-19 pandemic in the last few years is SARS-CoV-2. This study modeled the interaction of antibodies, white blood cells, epithelial cells, SARS-CoV-2 virus and COVID-19 vaccine by using the agent based modeling. The agent-based modeling is applied to simulate a complex system based on the rules in real phenomena which occur in nature. All of the agents have rules that are based on the characteristics and behaviour of each agent when interacting inside the body. The simulation was done in six scenarios and one additional scenario. Each scenario was distinguished by the time when the virus started to infect. The result of the simulation showed that the virus that was infected after the giving of the booster dose vaccine could be handled more optimally than the previous giving of the primary dose vaccine. Long term simulations for additional scenarios indicated that there was a need for a fourth dose vaccine dose to maintain the effectiveness of the vaccine. Viruses that interacted with the epithel cell and did a replicate-infection would increase the total entropy value, the entropy value would decrease if the virus could be handled properly by the antibodies.
Keyword: agent-based modeling, entropy, vaccine, virus

Judul: Analisis Kestabilan Model SEIR COVID-19 dengan Pengaruh Vaksinasi
Abstrak: Corona Virus Disease atau COVID-19 adalah penyakit menular yang cukup serius bagi kesehatan masyarakat. COVID-19 merupakan penyakit yang disebabkan oleh virus SARS-CoV-2. Tujuan dari penelitian ini adalah menentukan serta menganalisis kestabilan dari titik tetap pada model SEIR COVID-19 dan melakukan simulasi numerik untuk mengkaji pengaruh vaksinasi. Analisis kestabilan titik tetap ditentukan dengan aturan Descartes dan fungsi Lyapunov. Bilangan reproduksi dasar (ℛ0) didapatkan dengan menggunakan matriks next generation. Hasil penelitian ini menunjukkan bahwa titik tetap bebas penyakit bersifat stabil asimtotik bilamana ℛ0 < 1. Simulasi numerik dilakukan dengan menggunakan software Mathematica 13.0. untuk mengetahui pengaruh parameter terhadap bilangan reproduksi dasar. Penurunan laju perpindahan populasi individu terpapar ke populasi individu terinfeksi mengakibatkan bilangan reproduksi dasar menurun. Kenaikan tingkat pemberian vaksinasi pada populasi individu rentan akan mengakibatkan bilangan reproduksi dasar menurun. Dengan mengontrol kedua parameter tersebut, penyebaran penyakit akan dapat dikendalikan., Corona Virus Disease or COVID-19 is an infectious disease that is quite serious for public health. COVID-19 is a disease caused by the SARS- CoV-2 virus. The purpose of this study is to determine and analyze the stability of equilibrium points in the COVID-19 SEIR model and conduct numerical simulations to assess the effect of vaccination. The analysis of equilibrium-point stability is determined by Descartes' rule and the Lyapunov function. The basic reproduction number (ℛ0) is obtained using the next generation matrix. The results of this study show that disease-free fixed points are asymptotic stable when ℛ0 < 1. Numerical simulations were carried out using Mathematica 13.0 software to find out the effect of parameters on the basic reproductive number. A decrease in population movement rate of the population of exposed individuals to the population of infected individuals causes a decrease in the basic reproductive number. An increase vaccination rate in vulnerable individual populations will causes a decrease in the basic reproductive number. By controlling parameters, the spread of the disease will be controlled.
Keyword: stability analysis, basic reproductive numbers, numerical simulation, COVID- 19

Judul: Destruksi Hasil Samping Penambangan Timah Belitung Menggunakan Microwave untuk Ekstraksi Unsur Tanah Jarang
Abstrak: Rare earth elements (REE) in pure state are widely used for high-tech electronic equipment. Rare earth elements are contained in by-product of tin mining process. This study attempted to use microwave to destruct sample from by-product of tin mining in Belitung as an effort to obtain pure REE. Parameter of destruction is the ratio sample with NaOH, time, and energy. Preliminary test using X-ray fluorescence shows that the sample contains 377 ppm of lantanum (La) and 125 ppm of yttrium (Y). The best destruction condition occured in ratio sample:NaOH, 35:65 with percentage of destruction 19.96% and 4.48% for La and Y; the best destruction time is 30 minutes by the acquirement of 27.95% La and 4.61% Y; best energy at 450 watt by the acquirement of 38.52% La and 13.86% Y. To get La, destruction uses microwave better than oven, but contrary with Y.
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