Judul: Pemeriksaan suatu matriks data dengan metode biplot
Abstrak: Biplot adalah salah satu metode untuk menyajikan data secara visual. Dengan metode ini dapat diperiksa hubungan antar individu dan hubungan antar peubah. Metode ini dapat pula menerangkan posisi relatif individu amatan terhadap peubah. Disebut biplot karena terdiri atas plot dua jenis vektor. Unsur-unsur matriks data didekati oleh perkalian skalar kedua jenis vektor ini. Sifat-sifat data dalam biplot berkaitan dengan nilai yang digunakan. Nilai = 0 membuat ragam, peragam dan korelasi antar peubah diwakili oleh vektor-vektor pengaruh lajur. Jarak Mahalanobis antar individu amatan diwakili oleh jarak antar vektor-vektor pengaruh baris. Nilai x =1 memberikan plot skor komponen utama pertama dan kedua, Jarak antar vektor-vektor pengaruh baris mewakili jarak Euclideus antar individu amatan. (2) Biplot data yang diperiksa memiliki 2 0.9886. Peubah pertama berkorelasi negatif dengan peubah lain, dan cukup erat. Peubah kedua dan keempat serta peubah kelima dan ketujuh sangat erat korelasinya. Keragaman terbesar dimiliki oleh peubah pertama. Individu kesembilan memiliki nilai-nilai yang ekstrem. Pada peubah pertama nilainya sangat jauh di bawah rata-rata tetapi pada peubah lainnya leb lebih besar dari rataannya…
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Judul: Biplot dengan Matriks Koragam Biasa dan Kekar untuk  Pemetaan Provinsi Berdasarkan Prestasi Mahasiswa IPB
Abstrak: Analisis biplot merupakan salah satu bentuk Analisis Peubah Ganda (APG) yang dapat memberikan gambaran secara grafik tentang keragaman peubah, kedekatan antar objek serta keterkaitan peubah dengan objek yang dapat digunakan untuk menggambarkan sebuah tabel ringkasan dengan banyak peubah agar lebih menarik, lebih informatif, lebih komunikatif dan artistik.Analisis biplot telah terbukti sebagai alat yang sangat ampuh untuk menganalisis berbagai macam bentuk data berpeubah ganda.
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Judul: Production and formulation of methyl ester sulfonate-based surfactant from palm olein for enhanced oil recovery application
Abstrak: The remaining oil in a reservoir that cannot be produced using the natural driving force (primary recovery) is about 50 to 80% of the initial oil volumes (IOIP). A secondary recovery technique such as waterflooding can only increase the recovery as much as 5 to 20% of the IOIP. Therefore, a method known as Enhanced Oil Recovery (EOR) has to be implemented in the reservoir in the effort to recover much more oil. One of the EOR methods is surfactant injection. The injection of surfactant solution is aimed to significantly reduce the capillary forces in the reservoir by lowering the oil-water interfacial tension within the pore spaces. Once the capillary force is diminished, the reservoir oil is much easier to be displaced and moved toward the production wells. This is an excellent opportunity to develop a type of vegetable oil-based surfactants. One of potential surfactant types to develop is methyl ester sulphonate surfactant (MES). This study was aimed at producing MES surfactant and formula-based methyl ester sulfonate surfactant from palm olein to be applied for in the process of improving oil recovery using carbonate formation fluids. Results of the study showed that the best condition was achieved in a sulphonation process done in 3-4 hours with the flowrate of dry air of 1.8 kg/hour and a purification performed without the addition of methanol in a pH of 8. The best MES surfactant-based formula for EOR applications on the formation of carbonate was the one with the composition of 0.3% MES surfactant, 0.3% Na2CO3, and 15,000 ppm salinity. MES surfactant produced from this formula had more heat resistance, higher salinity, and higher hardness than the commercial surfactants did. Results of the performance test of surfactant-based formula showed that the MES surfactant formula was compatible with formation water and injection water. The formed phase was a lower phase which was relatively stable on a heating up to day 77 (reservoir temperature of 70 and 112 °C) with a range of interfacial tension of 10-2 dynes/cm. The adsorption reached 152.86 μg active matter/g core and the incremental oil recovery using synthetic core of 8-19% and using native core of 9.1%. Surfactant solution coreflooding test with bottom-up flow direction resulted in a greater oil recovery (16%) than that with top-down flow direction. This was caused by the influence of gravity.
Keyword: Palm Olein