This research aims at investigating the corrosion behavior and hardness of AISI Stainless Steel 304 (AISI SS 304) in corrosive hydrochloric acid solution and temperature variation treatment. In this study, the samples of AISI SS 304 are immersed for six (6) days in the corrosive acid solution at the temperature of 30°C and 50°C. The solution used as the corrosive media are HCl, FeCl3, and NaCl in the concentration of 5%, 10% and 15%. The results show that the higher the concentration of the solution, the higher the corrosion rate of AISI SS 304 will be, and the higher the temperature, the higher corrosion rate will also occur in all corrosion media. The corrosion that occurs in AISI SS 304 is mostly in the form of uniform corrosion and some pitting corrosion, and the value of hardness decreases after corrosion.
Investment is the wealth of one or more assets in the hope of future benefits. Things to consider in investing are profit and risk. So investors need to diversify their investments, which means investors need to form a portfolio through the selection of several assets so that risk can be minimized without reducing expected profits. The COVID-19 pandemic period had a big impact on the economy, especially for investors in making optimal portfolio formation. This study aims to determine the optimal portfolio formation during the COVID-19 pandemic using the Single Index Model. In this study a Single Index Model was be studied systematically and then translated into a programming. The data used are data of consistent shares included in the Jakarta Islamic Index (JII) shares over the past two years. Furthermore, these stocks are chosen which have an average return that is higher than the profits obtained if investors save their money in the bank. The results showed six JII companies included in the candidate for optimal portfolio formation. After the analysis, two shares were produced, namely BRPT with a proportion of 63.8043% and EXCL 36.1957%. The proportion is expected to provide a profit of 1.57% per week and a risk of 6.06% per week. With the proportions obtained, an investment simulation was then carried out during the COVID-19 pandemic. The results of the simulation obtained a gain of 0.0771504% every week. These results are below the risk-free return of assets (SBIS) during the COVID-19-19 pandemic with an average profit of 0.087445% per week. It was concluded that optimal portfolio formation with the Single Index Model did not provide optimal benefits during the COVID-19 pandemic.
Using inhibitors becomes an alternative way to reduce the level of corrosion. One type of the inhibitors proven effective is inorganic or chemical inhibitors. Regarding this, the purpose of this study is to determine the effectiveness of chemical inhibitors in reducing the level of corrosion. This study showed that the addition of natrium acetate and natrium was proven effective in reducing the corrosion, with the level of inhibitor efficiency of 75%. The result also showed that the inhibitors gave good performance to inhibit corrosion attack in natrium chloride acid medium, the form of corrosion that occurs in API 5L material is uniform corrosion.
One stochastic process that is often used to model real phenomena is the compound Poisson process (CPP). CPP is a process in which a component in the process of the events occurred is assumed to be a Poisson process with a certain intensity function (homogeneous or nonhomogeneous). Thinning process algorithm is usually used to generate events that occurred in the Poisson process, but not yet in CPP. This study aims to find out the algorithm to produce CPP which has the function of Poisson nonhomogeneous (NHPP) intensity, where in addition to knowing the process of events that occur, it also takes into account the extent of the consequences of these events. The value of the load caused by the Poisson process is assumed to be a family of i.i.d random variables and the variables are also independent of the Poisson process. The results of this study have obtained the thinning process algorithm and its generalizations for compound Poisson process having nonhomogeneous Poisson process (NHPP) intensity functions. This algorithm is the result of theoretical development and analysis of computational simulations that can be applied in various fields of science such as the analysis of reliability and risk models.
The purpose of this research is to analyze the formation of the optimal portfolio on the Jakarta Islamic Index 30 (JII30) stocks during the new normal period. The model used is a single index model. This study uses secondary data for the period December 2020 - November 2021 from stocks listed on JII30 on the Indonesia Stock Exchange. The results showed that the selected model provides optimal benefits. The risk-free asset return does not provide a higher return than the simulation results. Of the 30 stocks listed in JII30, obtained 7 stocks with the most significant proportion of funds, namely ERAA (25.72%), MDKA (24.87%), TLKM (17.98%), EXCL (12.82%), AKRA (7.54%), ADRO (6.73 %) and ANTM (4.34%). The formation of the optimal portfolio in this study produces an expected return of 0.009974 or 1%, where the portfolio return is above the market rate of return and the average risk-free rate. Meanwhile, the optimal portfolio risk obtained is 0.003173 and the standard deviation is 0.056327 or 5.63%. The impact of the Covid-19 pandemic which has subsided and the economy is getting better has resulted in the formation of an optimal JII30 portfolio that can be carried out and reduce investment risk during the new normal period. Keywords: Jakarta Islamic Index 30 (JII30), Single Index model, new normal, Optimal portfolio
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.