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Organic soil has a high content of water and compressibility. Besides that, it has a low specific gravity, density, and shear strength. This study evaluates the applicability of the soybean crude urease for calcite precipitation (SCU-CP) method and its effectiveness in organic soil as a soil-amelioration technique. Various soybean concentrations were mixed with a reagent composed of urea and calcium chloride to produce the treatment solution. Its effect on the hydrolysis rate, pH, and amount of precipitated calcite was evaluated through test-tube experiments. SEM-EDS tests were performed to observe the mineralogy and morphology of the untreated and treated samples. The treatment solution composed of the reagent and various concentrations of soybeans was applied to organic soil. The increasing strength of the organic soil was evaluated using direct shear (DS) and unconfined compression (UCS) tests. The test-tube results show that a hydrolysis rate of 1600 u/g was obtained when using 50 g/L of soybeans with a precipitation ratio of 100%. The mechanical tests show a significant enhancement in the parameters of the organic soil’s shear strength. A shear strength improvement of 50% was achieved in this study. A UCS of 148 kPa and cohesion of 50 kPa was obtained in the treated samples of organic soil. This research elucidates that the SCU-CP is an effective technique for improving organic soil’s shear strength.

Calcite-induced precipitation methods (CIPMs) have recently become potential techniques in geotechnical engineering for improving the shear strength of sandy soil. One of the most promising methods among them is enzyme-induced calcite precipitation (EICP). In this technique, a mixed solution composed of reagents and the urease enzyme, which produces calcite, is utilized as the grouting material. The precipitated calcite in granular soil provides ties among the grains of soil and limits their mobility, thus promoting an improvement in strength and stiffness and also a reduction in the hydraulic conductivity of sandy soil. This paper discusses the potential increase in the strength and stiffness of the soil, the additional materials for grouting, the effect of these materials on the treatment process, and the engineering properties of the soil. The possible sources of the urease enzyme and the applicability of the EICP method to other soil types are also discussed in this paper. The environmental and economic impacts of the application of EICP are also presented. The envisioned plans for application, potential advantages, and limitations of EICP for soil stabilization are discussed. Finally, the primary challenges and opportunities for development in future research are briefly addressed.

Solar energy is a clean energy, renewable, and available for the long term. The tool used to convert the energy generated from the intensity of sunlight into electricity is photovoltaic panels. However, due to the high cost and low efficiency, the use of the energy is still kind small compared to other types of energy sources. Thus, the need for an effective and flexible models, which resemble the characteristics of the actual photovoltaic (PV), so that we can perform simple manipulation of some data to figure out how to get the maximum performance possible. The characteristic of the solar panel output is specific and non-linear, it depend on the solar irradiation and the temperature of the solar panel. Because of it, it makes us difficult to get the Maximum Power Point (or abbreviated MPP) of the solar panels. Approach: Therefore, to solve these problems required the modeling of the solar panel for design and simulate the algorithms of Maximum Power Point Tracking (MPPT) to maintain the working point of solar panels fixed on the MPP. Overall, the designed system results carried are running well. The increase in the average value of the output voltage by 17%, from an average of 11.6 V before installation into 13.94 V after installation MPPT system. It also occurs in output power with an increase of 28%, from an average of 35.13 W before installing system MPPT into 48.9 W after installation MPPT system. The temperature effect on module voltage and output power before and after installation of the MPPT system that after the installation of the MPPT system, the voltage output of photovoltaic modules can be maintained around the desired maximum value that's equal to 12 V. But there was a drop in output power value compared to the prior installation MPPT system. This is caused by the output current value that cannot accommodate the value of the output voltage. So that the value of the output current is enough to produce the maximum output power is needed quantities corresponding load.

Tourism promotion in Pekanbaru is one step in increasing the number of tourists visiting Pekanbaru City. Through tourism promotion, tourists will find out where the locations are in Pekanbaru and information related to these tourist objects. This research aims to design a tourism promotion system using near-field communication (NFC) smart posters using smartphones in the city of Pekanbaru and apply NFC technology to Android smartphones in the city of Pekanbaru. Promote tourism in the city of Pekanbaru. They were testing this application with the System Usability Score, which had a good score of 74.30. This study shows that the planning and modeling of the smart poster system using NFC technology makes it easier to identify important information for every tourism activity in Pekanbaru. The results of this study are the design and product of an intelligent poster using NFC on an Android smartphone that can help users achieve information so that it is more effective and efficient.