Judul: Biogas Production from the Combination of Dairy Cow Manure and Layer Chicken Manure
Abstrak: Banyaknya populasi sapi perah dan ayam petelur di Jawa Barat dapat menghasilkan kotoran berlebih. Kotoran sapi perah memiliki C/N ratio dan kadar air yang tinggi dan kotoran ayam petelur memiliki keunggulan nutrisi dan protein yang tinggi. Biogas dapat dihasilkan dari kotoran sapi dan ayam petelur melalui fermentasi anaerobik. Tujuan penelitian adalah menganalisis produksi biogas dari kombinasi kotoran sapi dan ayam. Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) dengan tiga level perlakuan dan tiga ulangan. Perlakuan pada penelitian adalah S100A0 (100% kotoran sapi dan 0% kotoran ayam), S80A20 (80% kotoran sapi dan 20% kotoran ayam), dan S60A40 (60% kotoran sapi dan 40% kotoran ayam). Nilai TS awal dan TS akhir setiap perlakuan berbeda nyata (P<0,05). Volume biogas, kandungan metana, dan panjang nyala api bervariasi berdasarkan variasi level perlakuan S100A0 dibandingkan dengan S80A20 dan S60A40. Hasil analisis menunjukkan bahwa jika kotoran sapi dipadukan dengan kotoran ayam dengan takaran S60A40 menghasilkan biogas yang lebih maksimal., The high population of dairy cows and laying hens in West Java can result in excess manure. Dairy cow manure has a high C/N ratio and moisture content, while chicken manure from laying hens has high nutritional and protein advantages. Biogas can be produced from the manure of both dairy cows and laying hens through anaerobic fermentation. The research aims to analyze the biogas production from the combination of dairy cow and chicken manure. This study uses a Completely Randomized Design (CRD) with three treatment levels and three replications. The treatments in the study are S100A0 (100% dairy cow manure and 0% chicken manure), S80A20 (80% dairy cow manure and 20% chicken manure), and S60A40 (60% dairy cow manure and 40% chicken manure). The initial and final TS values of each treatment were significantly different (P <0.05). Biogas volume, methane content, and flame length varied based on the treatment level variations of S100A0 compared to S80A20 and S60A40. The analysis results indicate that when dairy cow manure is combined with chicken manure in the proportion of S60A40, it produces optimal biogas.
Keyword: Kotoran sapi perah, Kotoran ayam petelur, biogas, dairy cow manure, laying hen manure

Judul: Biogas Production from a Mix of Cow Manure with corn straw (Zea mays. L)
Abstrak: Biogas merupakan salah satu sumber energi alternatif yang dapat diperbarui karena menggunakan bahan baku yang berasal dari kotoran ternak. Tujuan penelitian ini adalah menganalisis roduksi dan kualitas biogas dari campuran kotoran sapi dengan jerami jagung (Zea mays. L). Penelitian dilakukan dengan 3 perlakuan yaitu kontrol sebanyak 100% kotoran sapi + 0% jerami jagung (S100J0), 75% kotoran sapi + 25% jerami jagung (S75J25), serta 50% kotoran sapi + 50% jerami jagung(S50J50) dan masing-masing 3 kali ulangan dengan analisis data menggunakan rancangan acak lengkap (RAL). Hasil penelitian menunjukkan bahwa campuran biogas kotoran sapi dengan jerami jagung berpengaruh nyata (P>0,05) terhadap produksi biogas yang dihasilkan (S100J0) menghasilkan produksi biogas yang paling tinggi. Suhu harian rata-rata hampir sama untuk semua perlakuan yaitu 27- 29 °C. Kandungan TS, VS awal dan akhir berturut-turut untuk S100J0, S75J25, dan S50J50 14,940; 12,916; dan 13,873. VS awal 12,660; 10,903; dan 10,996. TS akhir 10,643; 7,900; dan 10,550. VS akhir 6,286; 4,546; dan 7,323. Perlakuan S100J0 menghasilkan produksi yang lebih tinggi dan perlakuan penambahan jerami jagung 50% menghasilkan kualitas api yang baik berwarna biru, Biogas is a renewable alternative energy source because it uses raw materials derived from livestock manure. The purpose of this study was to analyze the production and quality of biogas from a mixture of cow dung and corm straw (Zea mays L). The study was conducted with 3 treatments, namely control as much as 0% corn straw or 100% cow dung (S100J0), 75% cow dung + 25% corn straw (S75J30), and 50% cow dung + 50% corn straw (S50J50) and 3 replications each with data analysis using a completely randomized design (CRD). The results showed that the mixture of cow dung biogas and corn straw had a significant effect (P>0,05) on the production of biogas (S100J0) produces the highest biogas production. The average daily temperature was almost the same for all treatments, namely 27-29 0C. The initial and final TS, VS content for S100J0, S75J25, and S50J50 14,940; 12,916; and 13,873. respectively. Initial VS 12,660; 10,903; and 10,996. Final TS 10,643; 7,900; and 10,550, and final VS 6,286; 4,546; and 7,323. The S100J0 treatment resulted in higher production and the addition of 50 % water hyacinth resulted in a good quality blue flame.
Keyword: alternative energy, biogas, corn straw, cow manure

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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