Judul: Performance Test of Disc Mill Machine for Porang Flour
Abstrak: Tanaman porang merupakan salah satu komoditas yang melimpah sehingga berpeluang tinggi menjadi komoditi ekspor dalam bentuk umbi segar, chip kering, dan tepung. Tepung hasil penggilingan umbi porang memiliki harga jual yang lebih tinggi dibandingkan harga umbi porang segar. Hal tersebut menciptakan dorongan untuk usaha pengolahan sehingga dibutuhkan mesin penepungan umbi porang dengan kinerja penepungan yang baik. Mesin penepungan tipe disc mill merupakan salah satu mesin penepugan yang dapat mengolah porang hingga ukuran 60-80 mesh. Penelitian ini bertujuan untuk menganalisis dan menguji performansi mesin disc mill terhadap hasil penepungan porang. Penelitian ini dilakukan di PT. Daud Teknik Maju Pratama pada Januari – Mei 2024 dengan menggunakan bahan berupa 1 kilogram porang berukuran 1 cm untuk setiap perlakuan. Pengujian dilakukan dengan menggunakan tiga kecepatan putar pada mesin disc mill (2160 rpm, 2750 rpm, dan 3340 rpm). Pada setiap perlakuan dilakukan pengulangan sebanyak tiga kali. Pengujian dilakukan untuk memperoleh data kapasitas penepungan, rendemen, susut tercecer, daya mesin, dan kualitas penepungan. Hasil performansi menunjukkan kapasitas penepungan mesin disc mill berkisar antara 5,96 - 9,89 kg/jam. Nilai rendemen penepungan pada perlakuan kecepatan putar 3340 rpm mendapatkan hasil tertinggi (91,37%) dan susut tercecer terendah (8,63%). Hasil kualitas penepungan terbaik juga didapatkan pada perlakuan kecepatan putar 3340 rpm dengan nilai tertinggi partikel halus 28,54% lolos ayakan mesh 80 dan persentase penurunan kadar air tertinggi 4,17%. Daya motor listrik yang dibutuhkan untuk mesin disc mill dengan kecepatan putar 2160 rpm, 2750 rpm, dan 3340 rpm secara berturut sebesar 1,0961 kW, 1,3486 kW, dan 1,5456 kW., The porang plant is an abundant commodity that has a high chance of becoming an export commodity in the form of fresh tubers, dried chips, and flour. Flour from grinding porang tubers has a higher selling price than the price of fresh porang tubers. This creates an impetus for processing businesses so a porang tuber flouring machine with good flouring performance is needed. The disc mill type pressing machine is one of the pressing machines that can process porang up to 60-80 mesh size. This study aimed to analyze and test the performance of the disc mill machine on the results of milling porang. This research was conducted at PT. Daud Teknik Maju Pratama from January to May 2024 using 1 kilogram of porang measuring 1 cm for each treatment. Tests were carried out using three rotational speeds on the disc mill machine (2160 rpm, 2750 rpm, and 3340 rpm). Each treatment was repeated three times. Tests were conducted to obtain data on milling capacity, yield, shrinkage loss, engine power, and milling quality. The performance results showed that the milling capacity of the disc mill machine ranged from 5.96 - 9.89 kg/hour. The milling yield value in the 3340 rpm rotational speed treatment was obtained the highest result (91.37%) and the lowest shrinkage (8.63%). The best milling quality results were also obtained in the 3340 rpm rotary speed treatment with the highest value of fine particles 28.54% passing the 80 mesh sieve and the highest percentage reduction in water content of 4.17%. The electric motor power required for disc mill machines with rotating speeds of
Keyword: porang, disc mill, performance test, porang flour, flouring

Judul: Performance Test of Ball Mill Type Grinding Machine for Porang Glucomannan Crystal Refining
Abstrak: Luas kebun porang yang meningkat setiap tahunnya menyebabkan stok umbi porang melimpah. Perbedaan harga tepung glukomanan dengan umbi porang mendorong pentingnya upaya pengolahan. Dibutuhkan mesin pengolah umbi porang menjadi tepung glukomanan dengan performansi mesin yang baik. Mesin penggiling tipe ball mill merupakan mesin yang mampu menghaluskan kristal glukomanan mencapai >100 mesh. Mesin ball mill yang digunakan merupakan rancangan mesin baru produksi PT. Daud Teknik Maju Pratama. Tujuan penelitian dilakukan adalah menganalisis dan menentukan performansi mesin ball mill terhadap hasil penghalusan kristal glukomanan porang. Penelitian dilakukan di PT. Daud Teknik Maju Pratama pada Januari – Mei 2023 dengan bahan masing-masing 150 gram setiap perlakuan. Pengujian dilakukan dengan menggunakan dua faktor perlakuan, kecepatan putar (21,2 rpm dan 41,6 rpm) dan lama proses (0,5 jam, 1,0 jam, 1,5 jam, 2 jam). Pengujian dilakukan dengan tiga kali pengulangan. Data yang diuji meliputi kapasitas tampung, persentase pengecilan ukuran, susut tercecer, daya mesin, dan kualitas tepung. Hasil uji performansi menunjukkan kapasitas tampung optimum mesin ball mill sebesar 12,5 kg/batch. Nilai persentase pengecilan ukuran tertinggi (96,27%) dan susut tercecer terendah (3,73%) didapatkan pada perlakuan 21,2 rpm selama 0,5 jam proses. Perlakuan 41,6 rpm selama 2 jam proses menunjukkan hasil kualitas tepung yang terbaik yaitu kadar air 11,87% dan kehalusan 63,97% lolos mesh 100. Kebutuhan daya motor listrik pada 21,2 rpm dan 41,6 rpm sebesar 0,8063 kW dan 0,9101 kW. Kapasitas kerja penghalusan terbaik ditunjukkan pada perlakuan kecepatan putar 41,6 rpm yaitu sebesar 1,560 g/min., The area of porang gardens which increases every year causes stocks of porang tubers to be abundant. The difference in the price of glucomannan flour and porang tubers encourages the importance of processing efforts. A machine to process porang tubers into glucomannan flour with good engine performance is needed. A ball mill type grinding machine is a machine capable of refining glucomannan crystals up to >100 mesh. The ball mill machine used is a new machine design produced by PT. Daud Teknik Maju Pratama. The purpose of the research was to analyze and determine the performance of a ball mill machine on the results of porang glucomannan crystal refining. Research conducted at PT. Daud Teknik Maju Pratama in January - May 2023 with 150 grams of each treatment. Tests were carried out using two treatment factors, rotational speed (21.2 rpm and 41.6 rpm) and processing time (0.5 hours, 1.0 hours, 1.5 hours, 2 hours). The test was carried out with three repetitions. The data tested included capacity, percentage of size reduction, lost losses, engine power, and flour quality. The performance test results show that the optimum capacity of the ball mill machine is 12.5 kg/batch. The highest percentage of size reduction value (96.27%) and the lowest scattered shrinkage (3.73%) were obtained at 21.2 rpm for 0.5 hours of processing. Treatment of 41.6 rpm for 2 hours of processing showed the best flour quality results, namely 11.87% moisture content and 63.97% fineness, passing 100 mesh. The power requirements of electric motors at 21.2 rpm and 41.6 rpm are 0.8063 kW and 0.9101 kW respectively. The best refining work capacity was shown in the treatment of 41.6
Keyword: Ball Mill, glucomannan flour, performance test, porang, refining

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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