Corona Virus Disease-19 (COVID-19) merupakan salah satu virus yang menyebabkan penyakit pada manusia dan hewan. Penyakit ini menyebabkan gangguan saluran pernapasan sedang atau berat. Telah dilakukan penelitian untuk mengetahui dinamika perkembangan COVID-19 dengan menggunakan model persamaan diferensial SIR. Model SIR merupakan salah satu pemodelan matematika yang menghubungkan antara individu yang rentan, terinfeksi dan individu yang sembuh. Berdasarkan hasil analisis dinamik model SIR dengan parameter laju infeksi dan laju kesembuhan berturut-turut yaitu beta = 0.5 dan gama=0.3 . Model SIR memiliki dua titik kesetimbangan yaitu kesetimbangan bebas penyakit pada titik E_0=(0,0,0)  dan titik kesetimbangan endemik pada titik E_1=(gama/beta,0,0) . Analisis kestabilan perilaku dinamik model S dan I pada titik kesetimbangan E_0=(0,0,0) memiliki sifat semi stabil dan E_1=(gama/beta,0,0)  memiliki sifat konstan. Hal ini menunjukkan bahwa akan terjadi epidemi COVID-19 dalam kurun waktu tertentu. Solusi dinamik model SIR pada titik kesetimbangan menggunakan solusi numerik metode runge-kutta orde 4 dengan solusi analitik menunjukkan suatu perbedaan yang tidak terlalu besar saat mencapai titik kestabilan.

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The persistently inequality of development between major cities and surrounding areas caused the displacement process, that are transport of supplies or human itself (urbanization) or commonly known as the transportation. The government has set a number of policies to overcome transportation problems, for example construct a double track railway line. This study aimed to find an alternative solution to overcome the problems of transportation, especially railway line by optimizing of using single track railway line which is given the term semi-double track using Petri Nets and Max-Plus Algebra. In the previous research, a Max-Plus algebra model has been developed based on the hierarchical structure of semi-double track railway line. In this research, the model is simulated against the problem of delay.

Every object has a natural frequency. When an object gets an external force same with their natural frequency, a resonance will occur. In this study we examined how the dynamic behavior of the mooringcable of Floating Production Storage Offloading (FPSO). The mooring type isCatenary Anchor LegMooring (CALM).What happens with mooringcable if it gets external force with a small frequency but it is so close to the natural frequency of the system. In the case of transmission cable, the phenomenon that describe this event is called the Galloping Phenomenon. The mathematics model of CALM system with a small frequency will be solved using Multiple scales method. The equilibrium point obtained is in the form of a center (stable). For negative, the amplitude value will be positive when the phase is zero (in-phase), at this condition if the initial conditions are chosen close enough to the equilibrium point then the cable will periodically oscillate with a limited phase value. If the initial conditions are selected a little further from the point of equilibrium, it will oscillate with amplitude the initial is the maximum amplitude and its value added of the dependent phase against time.

Tulisan ini membicarakan hubungan antara ketercapaian danketerkontrolan sistem linier diskrit linier. HUbungan ini dijelaskan den-gan kaidah-kaidah aljabar linier. Hasil akhir menunjukkan sistem terca-pai jika dan hanya jika sistem terkontrol.