Judul: Design of gathering-conveying unit of mobile sugar cane trash chopping machine
Abstrak: A machine for gathering and chopping the piles of sugarcane trash on the field after harvesting is being designed. As a part of the machine, a gathering-conveying unit was designed. Important data including condition and characteristics of trash were collected and used for designing the unit. The average bulk density of trash on the field was 7.7 kg/m3, the average pressure to compress the trash from 40 cm to 30 cm thickness was 50.65 N/m2, and the pressure to compress the trash from 27 cm to 8 cm thickness was 1166.60 N/m2. The unit was designed to be operated at 0.3 m/s forward speed, and having 60 cm working width. The unit was consisted of: a gathering reel, a pair of conveyors, cover-frame and power transmission components. Size and operational speed of moving components were determined by analyzing mass flow rate of the trash, and operating power of the components. The gathering reel was 100 cm in diameter and having 4 series of gathering fingers for drawing and feeding the trash into the conveyors. A pair of chain-conveyors equipped with L-shaped steel bars was set face to face on lower side and upper side for conveying and feeding the leaves to the chopping unit. The stationary test showed that the gathering reel and the conveyors could work properly. The average rotational speed of the conveyor shaft and the gathering reel were 34.03 rpm and 9.97 rpm, respectively. The working capacity of the unit was 400-500 kg/hour.
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Judul: Desain dan kinerja unit pemotongan serasah tebu dengan menggunakan pisau tipe reel
Abstrak: The problem of sugarcane trash after harvesting is experienced by the world's sugarcane plantations, including those in Indonesia. Large amount of sugarcane trash left in the field makes difficulties in soil management and plant maintenance. Current practice done by the sugarcane plantations was “burning before soil tillage”. However, the practice of burning cause unwanted impact to the environment and human health. Meanwhile, sugarcane trash still rich of nutrients for the land. Widely studied and has been proven that many sugarcane trash is very useful to increase the soil fertility. The trash size is still long so that it should be reduced to improve composting process. A prototype of reel type trash chopper has been designed and constructed with dimensions of 240 cm width, 268 cm length, and 133 cm height. The prototype was tested on 4 levels of reel rotational speeds (400, 450, 500, and 550 rpm) and 4 levels of trash densities (8, 16, 24, and 32 kg/m3). During the tests, cutting torque and rotational speed of the reel were measured using a torque-meter and a digital tachometer. The output of trash chopping were measured to know the quality of the chopping procces. The prototype chopped up sugarcane trash of about 1.7 - 3.2 cm length, with chopping capacity of 398 kg/hour. Results of the tests showed that cutting torque was in the range of 1.75 to 4.03 kg.m with the average of 2.88 kg.m, and average cutting power was 1.87 hp. Higher trash density caused a higher cutting torque and cutting power, while higher rotational speed caused a lower cutting torque and a higher cutting power. The highest cutting torque was 4.03 kg.m, when chopped sugarcane trash of 32 kg/m3 in trash density on 400 rotational speed. Increasing the rotational speed caused a shorter trash size.
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Judul: Pengaruh ENSO terhadap Variabilitas Ozon Total di Indonesia
Abstrak: Konsentrasi ozon total di atmosfer adalah jumlah ozon total yang ada di lapisan stratosfer dan troposfer yang lebih banyak merepresentasikan ozon stratosferik karena jumlahnya yang lebih banyak dibandingkan ozon troposferik. Ozon adalah salah satu gas aktif yang memiliki dampak besar terhadap keseimbangan radiasi dan iklim global. Penelitian ini bertujuan mengetahui variabilitas parameter suhu dan ketinggian geopotensial yang berkaitan dengan ozon total dan mengidentifikasi pengaruh fenomena ENSO terhadap jumlah ozon total di Indonesia. Data yang digunakan adalah data total kolom ozon, suhu, dan ketinggian geopotensial bulanan dari ERA5 dan indeks Nino 3.4 bulanan dari NOAA tahun 1996-2016. Hasil yang diperoleh dari analisis komposit adalah parameter suhu 100 mb dan ketinggian geopotensial 100 mb di lapisan stratosfer bawah pada saat El Nino mengalami anomali negatif, begitu pula dengan ozon, sedangkan pada saat La Nina menunjukkan pola yang terbalik, khususnya di Bulan Desember, Januari, dan Februari. Hasil analisis korelasi antara ozon total dengan indeks Nino 3.4 menunjukkan hasil koefisien korelasi pada musim kering (Mei-Oktober) berkisar -0.95 ≤ r ≤ 0.35 dan pada musim basah (November-April) berkisar -0.93 ≤ r ≤ 0.64 dengan sebagian besar korelasi bernilai negatif di seluruh wilayah Indonesia. Hasil tersebut menunjukkan bahwa adanya anomali positif dari suhu permukaan laut di wilayah Pasifik Timur (El Nino) akan menyebabkan penurunan ozon total, begitu pula sebaliknya., Total column ozone is the total amount of ozone in the stratosphere and troposphere layer, which represent more stratospheric ozone considering that it is more abundant than tropospheric ozone. Ozone is one of the active gases that has a major impact on the radiative forcing and the global climate. This study aims to determine the temperature and geopotential height parameters variability related to total ozone and to identify the effect of ENSO on the total amount of ozone in Indonesia. The data used are total column ozone, temperature, and geopotential height monthly data from ERA5 and monthly Nino 3.4 index from NOAA in 1996-2016. Using composite analysis, it found that temperature and geopotential height parameters in the lower stratosphere during El Nino will experience negative anomalies in line with negative anomalies ozone, while during La Nina shows an opposite pattern, especially in December, January, and February. The results of correlation analysis between total column ozone and Nino 3.4 index showed a significantly negative correlation coefficient almost all over Indonesia, with ranges -0.95 ≤ r ≤ 0.35 in the dry season, and -0.93 ≤ r ≤ 0.64 in the wet season. It indicates that the presence of a positive anomaly of sea surface temperature in the East Pacific region (El Nino) will cause a decrease in total ozone and vice versa.
Keyword: ERA5, ketinggian geopotensial, suhu, ozon total