This study was conducted with the aim to the clustering of provinces in Indonesia of the risk of the COVID-19 pandemic based on coronavirus disease 2019 (COVID-19) data. This clustering was based on the data obtained from the Indonesian COVID-19 Task Force (SATGAS COVID-19) on 19 April 2020. Provinces in Indonesia were grouped based on the data of confirmed, death, and recovered cases of COVID-19. This was performed using the K-Means Clustering method. Clustering generated 3 provincial groups. The results of the provincial clustering are expected to provide input to the government in making policies related to restrictions on community activities or other policies in overcoming the spread of COVID-19. Provincial Clustering based on the COVID-19 cases in Indonesia is an attempt to determine the closeness or similarity of a province based on confirmed, recovered, and death cases. Based on the results of this study, there are 3 clusters of provinces.
The premise of this work is the modification of the properties of chitosan-based film for possible use in food packaging applications. The biofilm was prepared via thermal and mechanical treatment through blending polymers with chitosan using Polyvinyl Alcohol (PVA) and loading different types of chemical agents, i.e., citric acid (CA), succinic acid (SA), and tetraethoxysilane (TEOS). The modification was carried out under high-speed homogenization at elevated temperature to induce physical cross-linkage of chitosan polymer chains without a catalyst. The findings showed that PVA improved the chitosan films’ Tensile strength (TS) and elongation at break (Eb). The presence of chemicals caused an increase in the film strength for all samples prepared, in which a 5% w/w of chemical in the optimum composition CS/PVA (75/25) provided the maximum strength, namely, 33.9 MPa, 44.0 MPa, and 41.9 MPa, for CA-5, SA-5, and TEOS-5, respectively. The chemical agents also increased the water contact angles for all tested films, indicating that they promoted hydrophobicity. The chemical structure analysis showed that, by incorporating three types of chemical agents into the CS/PVA blend films, no additional spectral bands were found, indicating that no covalent bonds were formed. The thermal properties showed enhancement in melting peak and degradation temperature of the blend films, compared to those without chemical agents at the optimum composition. The X-ray diffraction patterns exhibited that PVA led to an increasing crystallization tendency in the blend films. The morphological observation proved that no irregularities were detected in CS/PVA blend films, representing high compatibility with both polymers.
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.
Compound Poisson process (CPP) is one of the models of stochastic processes in which this model can model a real phenomenon that has an element of uncertainty in the process. CPP has two main components, those is a Poisson process on the component of the poses of an event that occurs and a sequence component of the magnitude as a result of the process of events that occur. This research aims to develop an algorithm to generate random numbers from CPP with a component in the Poisson process in the form of a nonhomogeneous Poisson process (NHPP) and a component in the magnitude of the effect in the form of an exponential distribution (CPP-NHPP-ED). The method used is using the acceptance and rejection method in the form of Thinning process techniques. The results of the study obtained several algorithms, namely the algorithm for CPP-HPP-ED, CPP-NHPP-ED type 1, and CPP-NHPP-ED type 2. These algorithms can be used for computer simulation analysis that can be applied to various fields of science and engineering.
There are still many people who do not know and understand the COVID-19 virus, which is still new. Some of the news that can be accessed on news search links show a lot of oppression and stigma against people called COVID-19. Stigma, among other things, arises because society ignores new diseases and there is no cure, stigma can be suppressed and lost if society finds out about it. Generally, service activities are conducted to provide knowledge and understanding of COVID-19 and how to prevent it. Stigma prevention is done by environmental disinfection activities, mask distribution for adults and children as well as counseling on clean and healthy living habits and physical distance, disinfection activities and mask distribution done to give a sense of peace to the population. Clean and healthy lifestyle guidance activities and physical distance are done to provide correct information. Generally, service activities are conducted to provide knowledge and understanding of COVID-19 and how to prevent it. With the right knowledge, stigma will not occur in society. This service can improve people's knowledge and understanding of COVID-19, live a new life pattern, and understand the attitudes and views that should be present when dealing with people called COVID-19 so that people can live their daily lives calmly and vigilantly
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
Modeling of electromagnetic energy harvesting on the vehicle suspension system is presented in this paper. This study uses the up and down movement oscillation of the shock absorber to vibrate the SDOF module which is consist coil and a permanent magnet. The mathematical model is developed by using Faraday law to estimate the electrical response of the energy harvester. The effect of resistance load is admitted in the mathematical model its effect on the performance of the energy harvester. The effect is investigated for different values of frequency and resistance load. This method proposed regenerative absorber is effective and practical for renewable energy applications.
Stirling machine has the advantage that it can utilize all kind of fuel, so that it is suitable for biomass utilization. In this study the analysis of best design of stirling machine different from previous study was carried out, which is design innovation on alpha type stirling machine by making phase angle become 180°, with the aims of lowering the gravitational force when cool cylinder is compressed, because the existing phase angle used is (90°) has the disadvantage of cool cylinder which is perpendicular, so that the compression is against gravitational force. The designing method was conducted by using Quality Function Deployment. The result of this study was to obtain the best variance of shape and machine stirling design dimension, which is variance 5, biomass stove- pulley and belt- was directly used. Variance 5 is chosen because it was the most suitable with the designed specification. Biomass stove is chosen as heat source, because the fuel used is classified as alternative fuel. Pulley and belt were chosen as mechanism of work transmission, because it has less noise compare to sprocket and chain. Its output work was directly chosen because its construction is simpler and the energy used is more optimal.
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