High-Order Finite-Volume Schemes for Magnetohydrodynamics

New high-order finite-volume numerical schemes for the magnetohydrodynamics equations are proposed in two and three dimensions. Two different sets of magnetohydrodynamics equations are considered. The first set is the ideal magnetohydrodynamics system, which assumes that the fluid can be treated as a perfect conductor. The second set is resistive MHD, which involves non-zero resistivity. A high-order central essentially nonoscillatory (CENO) approach is employed, which combines unlimited k-exact polynomial reconstruction with a monotonicity preserving scheme. The CENO schemes, which were originally developed for compressible fluid flow, are applied to the MHD equations, along with two possible control mechanisms for divergence error of the magnetic field. The hyperbolic fluxes are calculated by solving a Riemann problem at each cell interface, and elliptic fluxes are computed through k-exact gradient interpolation where point-wise values of the gradients are required. Smooth test problems and test cases with discontinuities (weak or strong) are considered, and convergence studies are presented for both the ideal and resistive MHD systems. Several potential space physics applications are explored. For these simulations, cubed-sphere grids are used to model the interaction of the solar wind with planetary bodies or their satellites. The basic cubed-sphere grid discretizes a simulation domain between two concentric spheres using six root blocks (corresponding to the six faces of a cube). Conditions describing the atmosphere of the inner body can be applied at the boundary of the inner sphere. For some problems we also need to solve equations within the inner sphere, for which we develop a seven-block cubed-sphere grid where the empty space inside the interior sphere is discretized as a seventh root block. We consider lunar flow problems for which we employ the seven-block cubed-sphere mesh. Ideal MHD is solved between the inner and outer spheres of the grid, and the magnetic diffusion equations are solved within the inner sphere, which represents the lunar interior. Two cases are considered: one is without intrinsic magnetic field, where only a wake is expected without any bow shock forming ahead of the Moon, and the second is with a small dipole moment to model a lunar crustal magnetic anomaly, in which case a small-scale magnetosphere is expected ahead of the region with the magnetic anomaly

The Determinants of COVID-19 Vaccine Acceptance in Sumatra

In light of the current coronavirus disease 2019 (COVID-19) vaccination programs being implemented worldwide, this study aimed to evaluate the COVID-19 vaccine acceptance survey in Indonesia conducted by the World Health Organization (WHO), the Ministry of Health of the Republic of Indonesia, the National Immunization Technical Advisory Group (NITAG), and the United Nations Children's Fund (UNICEF), published in November 2020. It was found that Sumatra Island having lower COVID-19 vaccine acceptance rates, with Aceh Province displaying the lowest level of vaccine acceptance. Thus, a cross-sectional study was conducted, and a logistic regression analysis was used to identify the factors affecting COVID-19 vaccine acceptance. Out of 368 respondents who participated in the survey, 143 (38.9%) accepted the vaccine, and 225 (61.1%) refused it. Vaccine safety concerns constituted the most reported reason for refusal (43.6%). This study also found that province of residence and basic immunization status were determinants of COVID-19 vaccine acceptance in Sumatra. Concerns regarding vaccine safety might be the reason for the low level of vaccination in Sumatra. Increased education and encouragement from healthcare professionals and regional authority figures can alleviate public concerns and improve vaccine acceptance

Laporan Kerja Praktek PT. Lumina Packaging

PT. Lumina Packaging merupakan pabrik yang bergerak pada bidang manufaktur packaging. Produk yang dihasilkan PT. Lumina Packaging adalah kemasan plastik seperti standing pouch, three side seal, center seal, gusset center seal, dsb. Pabrik yang bergerak di bidang packaging memiliki tantangan yang besar karena waste yang dihasilkan termasuk besar dan produk yang dibuat adalah produk yang tidak mudah terurai di alam, dan tentu saja membutuhkan biaya yang besar untuk mengelola limbah tersebut. Ditambah jenis produk yang bervariasi sehingga butuh keepatan dan efisiensi yang tinggi dalam melakukan proses produksi. Oleh karena itu PT. Lumina Packaging perlu untuk meningkatkan efisiensi terutama dalam meminimasi waste agar biaya yang dikeluarkan untuk pengelolaan limbah maupun turnover produksi berkurang. Waste yang dominan pada proses produksi di PT. Lumina Packagign ini adalah flui (terlipat), melet (asimetri), dan gelembung (bubble) sehingga dilakukan penelitian terhadap penyebab-penyebab waste tersebut. Sehingga didapatkan hasil untuk meminimasi flui (terlipat) diperlukan perawatan rutin pada mesin terutama rubber yang berpotensi besar menyebabkan waste, melakukan crosscheck saat mengukur kekentalan adhesive, melakukan training pada personnel, dan melakukan proses QC (Quality Control) yang lebih ketat. Untuk meminimasi melet (asimetri) diperlukan uji coba design, melakukan pemeriksaan sensor setiap akan memulai proses produksi, melakukan QC (Quality Control) yang lebih ketat, dan training operator. Dan untuk meminimasi gelembung (bubble), diperlukan pengendaian kualitas pada saat material masuk dan keluar dari gudang bahan baku, melakukan training atau pelatihan pada operator agar hasil yang didapatkan lebih konsisten, melakukan proses QC (Quality Control) dengan lebih ketat, serta melakukan crosscheck pada saat mengukur adhesive