Reaksi Pasar Modal Index LQ45, Index Consumer Goods, Index Manufacture dan Index Finance pada Peristiwa Pandemi Covid-19 April 2020 di Indonesia

Pandemi Global Virus Corona (Covid-19) telah mewabah di seluruh dunia. Di Indonesia dan hampir semua negara di dunia telah mengurangi aktifitas ekonominya, akibat adanya pandemi global ini. Peneliti menguji dampak pandemi Covid-19 di Indonesia, khususnya Pasar Modal pada Index LQ45, Index Consumer Goods, Index Manufacture dan Index Finance Bursa Efek Indonesia. Sample diambil pada masing-masing index, yaitu harga saham dan likuiditas saham, selama 13 hari pengamatan di bulan April 2020 yang dibandingkan dengan tahun sebelumnya. Metode penelitian menggunakan Event Study dengan Least Square Regression. Hasil penelitian menunjukkan bahwa peristiwa pandemi Covid-19 berdampak signifikan pada harga saham Index LQ45, Index Consumer Goods, Index Manufacture dan Index Finance. Sedangkan pada likuditas saham peristiwa pandemi Covid-19 hanya berdampak signifikan pada Index Consumer Goods dan Index Manufacture. Kata kunci: Likuidtas Saham, Harga Saham, Corona (Covid-19)

Characteristics of Modal Sound Radiation of Finite Cylindrical Shells

Characteristics of modal sound radiation of finite cylindrical shells are studied using finite element and boundary element methods in this paper. In the low frequency range, modal radiation efficiencies of finite cylindrical shells are found to asymptotically approach those of the corresponding infinite cylindrical shell when structural trace wavelengths of the cylindrical shells are greater than the acoustic wavelength. Modal radiation efficiencies for each group of modes having the same circumferential modal index decrease as the axial modal index increases. They converge to each other when the axial trace wavelength is much greater than the circumferential trace wavelength. The mechanism leading to lower radiation efficiency of modes with higher circumferential modal index of short cylinders is explained. Similar to those of flat plate panels, change in slope or waviness is observed in modal radiation efficiency curves of modes with higher order axial modal index at medium frequencies. This is attributed to the interference of sound radiated by neighboring vibrating cells when the distance between nodal lines of a vibrating mode is in the same order or smaller than the acoustic wavelength. The effects of the internal sound field on modal radiation efficiencies of a finite open-end cylinder are discussed.