Judul: Pemanfaatan Material Organik dalam Meningkatkan Kuat Geser Pasir
Abstrak: Penelitian ini dilakukan untuk mengevaluasi pengaruh penambahan kedelai dan susu dalam teknik enzyme mediated calcite precipitation (EMCP) sebagai metode peningkatan kekuatan geser pasir. Pasir terlebih dahulu dievaluasi melalui uji berat jenis dan analisis saringan untuk menentukan klasifikasi pasir. Uji pengendapan kemudian dilakukan untuk menemukan konsentrasi enzim urease, urea, dan kalsium klorida yang optimal dalam larutan EMCP. Larutan tersebut kemudian divariasikan oleh kedelai dan susu dan kemudian digunakan untuk memperbaiki kekuatan pasir melalui metode perkolasi. Pengaruh penambahan kedelai dan susu terhadap kuat geser pasir dianalisis dengan menggunakan uji kuat tekan bebas. Hasil pengujian menunjukan penambahan kedelai 60 g/L meningkatkan kekuatan pasir sepuluh kali lebih tinggi daripada larutan EMCP tanpa bahan tambahan dengan kekuatan maksimum 185 kPa sementara penambahan susu 12 g/L memperoleh kekuatan maksimum kurang dari 12 kPa. Jumlah kalsit yang diendapkan dalam sampel tanah juga dievaluasi melalui uji kuantifikasi kalsit. Kalsit 2.8% dari massa kering tanah terbentuk ketika 60 g/L kedelai ditambahkan. Penelitian ini membuktikan bahwa penambahan kedelai dalam teknik EMCP melalui perkolasi dapat meningkatkan kekuatan geser pasir secara signifikan sedangkan penambahan susu tidak berpengaruh signifikan terhadap kekuatan geser pasir.
Keyword: bahan organik dalam perbaikan tanah, metode perkolasi, teknik presipitasi kalsit, bahan tambahan urease, grouting kimia

Judul: The Effect of Variations in Reagent and Soybeans Size  on The SCU-CP Method on The Strength and Permeability of Sandy Soil
Abstrak: Meningkatnya kebutuhan lahan menyebabkan pembangunan dilakukan pada berbagai kondisi lahan, termasuk tanah pasir yang memiliki daya dukung rendah. Penelitian ini menerapkan metode soybean crude urease calcite precipitation (SCU-CP) untuk perbaikan tanah pasir dengan memvariasikan reagent dan ukuran kedelai yang digunakan, terdapat 4 variasi dengan reagent lab. dan tech. grade dan biokatalis gasol dan kedelai 0.1-0.5 mm. Penelitian ini bertujuan untuk menganalisis pengaruh variasi reagent dan ukuran kedelai terhadap kekuatan tanahpasir melalui pengujian unconfined compressive strength (UCS) serta nilai permeabilitas setelah dilakukan proses SCU-CP. Berdasarkan hasil pengujian diketahui variasi bahan reagent dan ukuran kedelai memengaruhi kekuatan pasir. Penggunaan bahan reagent lab. grade dan kedelai 0.1-0.5 mm menghasilkan kekuatan lebih besar dibanding lainnya dengan nilai tertinggi 66.18 kPa pada umur 14 hari. Berdasarkan hasil UCS diketahui pula bahwa umur sampel tidak berpengaruh signifikan terhadap kekuatannya. Penggunaan metode SCU-CP mampu menurunkan nilai permeabilitas tanah pasir hingga 50%. Variasi reagent dan ukuran kedelai berpengaruh terhadap nilai permeabilitas pasir, meskipun pengaruhnya tidak signifikan sebab nilai permeabilitas pada setiap sampel tidak jauh berbeda
Keyword: kalsit, pasir, permeabilitas, SCU-CP, UCS

Judul: Characteristic of Overshooting Top (OT) Based on  Himawari  8  Satellite  as  a  Convective  Cloud  Feature  that  Generates  Extreme Weather in the Java Island Region
Abstrak: Overshooting Top (OT) is a feature at the top of a convective cloud that is associated with extreme weather. Research on OT in tropical Indonesia is still very limited. The existence of geostationary satellites with wide area coverage and fast frequency observations is useful for observing the fast dynamics of the OT life cycle. Therefore, this study intends to analyze the relationship between OT and extreme weather, updraft and thermodynamic conditions of OT when extreme weather occurs, the best objective method for detecting OT in the day time and night time, and the spatiotemporal distribution of OT in the tropical region of Java Island during the 2018-2021 period. Based on visual analysis using visible channel and Himawari 8 sandwich products, 87% of extreme weather events in Java were accompanied by the appearance of OT. It indicates that the presence of the OT pattern is a convection cloud pattern or feature that is closely related to extreme weather events for the Java Island region. The existence of a time lag between the appearance of OT and extreme weather events on Java Island indicates that the OT of convection cloud can be used as a precursor or nowcasting for the appearance of extreme weather. Most of the convective cloud OT features during extreme weather events on Java Island have altitude that were only able to exceed the altitude of the equilibrium level and few were able to exceed the tropopause level of 9 km – 16 km. The difference in atmospheric conditions during extreme weather events on Java Island, which is in the tropics and subtropics, is a strong and unstable convective energy condition characterized by a larger CAPE, as well as unstable KI, LI, SI and TTI values. It is offset by kinematic factors in the form of a weak vertical wind shear (bulk wind shear 0-6 km) and a higher freezing point height. The difference between extreme weather events in the Java Island region and other tropical regions compared to subtropical regions is the strong updraft speed of convection clouds. The IRW Texture COMB algorithm based on the IRW-Texture Gradient modification and the COMB algorithm shows a significant increase in quality for detecting OT and non-OT pixels in Java. Rainy days with rainfall > 50 mm/day are very common in areas with an altitude of > 500 m. On the other hand, the level of convection activity which is indicated by the presence of OT and lightning is significantly reduced in this area. OT of convective clouds appear more frequently during the DJF season and less frequently during the JJA season. OT often appears during the day time and rarely at night time. Most OTs appear in the central part, away from the south and north coasts of Java Island during the day, while OTs that appear near the south and north coasts of Java Island can appear in the morning or afternoon.
Keyword: convective clouds, extreme weather, Overshooting Tops, Himawari 8 Satellite