Judul: Evaluasi kinerja tarik traktor kubota B6100 dengan bahan bakar cocodiesel
Abstrak: Perkembangan teknologi yang semakin cepat, dan kebutuhan manusia terhadap energi meningkat, maka muncul kekuatiran terhadap krisis energi jika masih menggunakan bahan bakar dari sumberdaya alam yang tidak dapat diperbarui. Bahan bakar yang dipakai pada traktor awalnya berasal dari solar. Belakangan ini kelangkaan bahan bakar fosil memicu melambungnya harga bahan bakar, maka bahan bakar nabati menjadi salah satu solusi untuk penaggulangan masalah ini. Sumber tenaga yang tersedia pada traktor dengan bahan bakar nabati seperti Cocodiesel diharapkan menjadi salah satu pemecahan masalah krisis bahan bakar. Pengertian cocodiesel adalah biodiesel yang dibuat dengan mereaksikan minyak kelapa dengan methanol, yang merupakan reaksi transenterifikasi dan menggunakan katalis pada suhu dan waktu tertentu. Minyak cocodiesel ini memiliki emisi rendah, titik nyalanya tinggi, dan senyawa mono alkil ester dari trigliserida ester cukup baik. Di samping itu, cocodiesel mempunyai sifat mudah terurai, tidak beracun, dan tidak mengeluarkan asap, sehingga aman dipakai serta ramah lingkungan.
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Judul: Kajian Kinerja Tarik Traktor Tangan dengan Menggunakan Bahan Bakar Biodiesel Minyak Sawit
Abstrak: This study discusses the tractive performance of hand tractor (drawbar pull, drawbar power, and cultivated field capacity using mouldboard plough) fueled with biodiesel from palm oil and analysed the economics of biodiesel implementation as fuel. The tests were performed on Huanghai DF-12L. In this study, palm oil biodiesel are tested as diesel fuels in neat (B100) and blended forms with diesel fuels commercial (B20, B40, B60, B80); the performance of hand tractor using biodiesel in neat and blended forms compared with using diesel fuels commercial. In order to determine the traction performance characteristic, hand tractor operated at constant engine speed mode 2000 rpm (the full load condition of the engine). Hand tractor loaded by Yanmar YM330T (four wheel tractor) that operated at five levels engine speed mode that is 1200 – 2000 rpm with 200 rpm increments. The tractive tests were performed on grass track and concrete track, whereas cultivation performed in dry land. The results indicated that drawbar pull and drawbar power of hand tractor on grass track and concrete track were uniformed (especially on grass track); hand tractor fueled with B40 and B100 showed increase trend compared to diesel fuels commercial, whereas other fuels tested showed decreased trend. Otherwise the cultivated field capacity of hand tractor fueled biodiesel from palm oil closely followed those of fueled with diesel fuels commercial. Based on this study, the implementation of biodiesel from palm oil either neat or blended forms are suitable as alternative diesel fuel for hand tractor although more expensive compared to diesel fuels commercial.
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Judul: Phylogeography and Species Limits in the Papuan White Snake (Micropechis ikaheka) (Reptilia: Serpentes: Elapidae)
Abstrak: Papua white snake, Micropechis ikaheka, has been distingushed into two subspecies M.i. ikaheka and M.i. fasciatus. However, due to lack of data on their morphology, distribution and ecology, both subspecies often ignored in scintific discussions and refers only byas , Micropechis ikaheka. This study was designed to document the differences between M.i. ikaheka and M.i fasciatus by using scales characteristics and reproductive organ or hemipenes. The study also examine, zoogeography, habitat, diet and cannibalism of both subspecies to better understanding the the ecology of one of the most venomous snakes in the world. This study consists of three topics with method and also different in the size samples, respectively. The first study is the histology and microtopography of the skin were studied using paraffin method and Scanning Electron Microscope (SEM). The second is the hemipenis were examined by following Myers and Cadle (2003), and Zaher and Prudente (2003). The third is the abdominal surgery was carried out to document diet type and the investigate phenomenon of cannibalism in the snake. Specimens for this study came from the collection from Museum Zoologicum Bogoriense (MZB) and Universitas Negeri Papua’s Laboratory (LZU). The research result also indicated that the markers of skin and hemipenis described the same structure and microornamentation in all M. ikaheka groups being compared. Based specimens examined morphological descriptions do not s support the further differentiation in Micropechis. In short, two markers that used in this study could not sufficiently indicate the differences in the level of species and subspecies of M. ikaheka. The study, however, were able to delineate zoogeography and skin color patterns, which fall into four groups: M. i. ikaheka; M. i. fasciatus. M. i. ssp. “intermediate”; and M. i. ssp “black”. This study also revealed that color variations did not overlap in their geographic distribution. It is therefore, it suggested that environmental factors may contribute to the skin color variations. It also assumed that habitat discontinuous and biogeography factors may also cause the loss of the connection between the original populations (vicarians) or follow colonization events (dispersal). The examined of 22 stomach contents of M. ikaheka shows this species is carnivorous, and prey on vertebrates such as amphibians, fish, reptiles, and Mammals. These snakes are opportunistic predators since they prey on all that can be captured, but mainly reptiles (61.5%), followed by mammals and fish (both 15.4%), and amphibians (7.7%). Although categorized as terrestrial animal, the diet study showed that M. ikaheka snakes often go into the water to hunt for fish (the sample from Yapen island), including eel (the sample from Aru island). Based on prey items indentified, there is evidence that M. ikaheka is cannibal. At this time, there still no record on reason for cannibalism, but it is assumed that cannibalism was due to competition between populations and means to control population.
Keyword: geographic variation, white snake, papua