Judul: Wire electroplating sludge sebagai katalis pembakaran batu bara
Abstrak: A fuel additive (combustion catalyst) can improve the combustion efficiency by promoting complete oxidation of fuel. Combustion catalyst in this research was composed of wire electroplating sludge dispersed in a mixture of vegetable oil, water, and surfactant. Four types of catalyst suspensions were prepared, namely A (2% sludge); B (3% sludge); C (2% sludge, 3% oxalyc acid); and D (3% sludge, 3% oxalyc acid). Addition of oxalyc acid in catalyst suspension C and D showed significant effects on combustion efficiency. Each suspension was applied in coal having caloric value of 5235.09 cal/g. The concentration of catalyst suspension in coal was about ±0.1% w/w. The results of activity test by using differential thermal analyzer showed that the energy efficiency from catalyst A was 62.21%, B: 97.19%, C: 77.96%, and D: 97.54%. Catalyst D (3% sludge, 3% oxalyc acid) is the best catalyst suspension that can be used as coal combustion catalyst.
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Judul: Meta-Analysis of the Effectiveness of Shell-based Calcium Oxide Catalysts on Biodiesel Transesterification
Abstrak: Katalis kalsium oksida (CaO) dari cangkang kerang telah banyak diteliti dengan beragam proses dan mempengaruhi transesterifikasi biodiesel. Penelitian bertujuan untuk menentukan efektivitas katalis heterogen CaO berbasis cangkang kerang untuk transesterifikasi biodiesel dari sejumlah penelitian terkait dengan metode meta-analisis. Prosedur penelitian meliputi penelusuran literatur, seleksi sumber pustaka, pembuatan database, dan analisis data kelompok berdasarkan perlakuan katalis CaO. Screening jurnal diperoleh 1308 jurnal ilmiah, 6 jurnal diinklusi kedalam meta-analisis dengan total 20 studi. Meta-analisis memiliki nilai rerata effect size seluruh studi dengan 11,494 berkorelasi positif atau perlakuan katalis CaO berpengaruh pada transesterifikasi biodiesel. Efektivitas katalis CaO pada transesterifikasi biodiesel disertai estimasi rerata effect size secara berturut-turut adalah proses perlakuan kalsinasi-hidrasi-dehidrasi (1114,047) > impregnasi KBr diaktivasi (363,675) > impregnasi fly ash (23,855) > kalsinasi (7,465) > impregnasi Zn, Al diaktivasi (0,087). Kesamaan pola persebaran data melalui funnel plot memperlihatkan distribusi yang simetris atau tidak dipengaruhi oleh bias publikasi., Calcium oxide (CaO) catalysts from shells have been widely studied with various processes and affect the transesterification of biodiesel. The aim of the study was to determine the effectiveness of a shell-based CaO heterogeneous catalyst for biodiesel transesterification from a number of studies related to the meta-analysis method. The research procedure included literature search, selection of library sources, database, and analysis of group data based on CaO catalyst treatment. Screening obtained 1308 scientific journals, 6 journals were included in the meta-analysis with a total of 20 studies. The meta-analysis had a mean effect size for all studies with 11.494 positive correlations or the CaO catalyst treatment had an effect on biodiesel transesterification. The effectiveness of CaO catalyst in biodiesel transesterification with the estimation of the mean effect size respectively were calcination-hydration-dehydration process (1114.047) > activated KBr impregnation (363.675) > fly ash impregnation (23.855) > calcination (7.465) > activated Zn, Al impregnation (0.087). The similarity of data distribution patterns through funnel plots showed a symmetrical distribution or was not influenced by publication bias.
Keyword: energi terbarukan, impregnasi, transesterifikasi, impregnation, renewable energy, transesterification

Judul: Invers dari Matriks Tridiagonal Jacobi
Abstrak: Suatu matriks berukuran n×n dinamakan matriks tridiagonal jika untuk . Karya ilmiah ini memberikan algoritma yang mudah untuk menemukan invers ( dari matriks tridiagonal Jacobi yang simetrik dan nonsimetrik. Setiap elemen pada matriks tridiagonal ini adalah bilangan real. Terdapat 3 lema dan 2 teorema untuk menentukan . Lema pertama menunjukkan persamaan utama dalam membuktikan lema-lema dan teorema-teorema selanjutnya. Invers dari matriks yang simetrik dibuktikan oleh lema kedua yang menunjukkan elemen-elemen baris ke- dari . Selanjutnya, lema kedua dilengkapi dengan teorema pertama yang menunjukkan elemen-elemen dengan . Invers dari matriks yang nonsimetrik dibuktikan oleh lema ketiga yang menunjukkan elemen-elemen dengan dan elemen-elemen dengan dibuktikankan oleh teorema kedua.
Keyword: symmetric, nonsymmetric, matrix