Dryland area in Indonesia reaches 108.8 millions ha (69.4%) of the total dry land with the potential to expand the area of food crops reaching 7.1 million ha, which is dominated by ultisol and oxisol soil types. Plant constraint cultivation on ultisol soil types is the acidic soil pH with high Al and Fe levels. One of the efforts that can be made to cultivate plants on ultisol soil is the selection of plants that are tolerant of Fe stress. This study aimed to determine a tolerance level and F6 red rice lines that were tolerant of iron (Fe) stress in ultisol soils. The experimental design used was factorial Completely Randomized Design (CRD) consisting of 2 factors, the first factor consisted of 12 treatments (10 test lines and 2 comparison varieties) and the second factor was iron stress with concentrations (0 ppm and 551,55 ppm). The stress was applied after 3 WAP. The stress resistance test to iron (Fe) should that all lines of red rice F6 on ultisol soils have a score of 1 which indicates the stress tolerance of Fe at a concentration of 551,55 ppm Fe. The 23A-56-30-25-12 and 23A-56-30-25-13 lines were the best lines that were tolerant of 551,55 ppm iron (Fe) stress with the highest growth and yield. The lines tested can be developed on ultisol soils because they are tolerant of Fe.
PT. X is one of the companies engaged in the field of an aircraft-maintenance and repairing services. PT. X classifies the aircraft spare parts into three groups namely rotable, repairable, and expandable. PT. X has a problem of having shortage inventory of the expandable spare part with 9 unit total of shortage in 2016. If this problem occurs continuously, it can increase the total inventory cost. Therefore, this study discusses the improvement of the inventory control of the expandable spare parts. The first phase of this study is forecasting the existing spare parts of the A Classes. Then, we determine the maximum inventory and the average inventory in warehouse using minmax method. After that, we determine the inventory level which covers ordering period (T), maximum inventory (R) and the average inventory in warehouse using Periodic Review Models. The final phase of this study is comparing the total inventory cost between Periodic Review Models and Min-Max method.
ABSTRAK: Salah satu alternatif dalam mendukung ketersediaan sumber daya energi terbarukan adalah dengan memanfaatkan sumber dari non fosil seperti bioetanol. Bioetanol merupakan etanol yang dibuat dari biomass yang mengandung komponen pati (karbohidrat) atau selulosa yang selanjutnya di fermentasi menggunakan bantuan mikroorganisme (Sacharomyces cerevisiae). Karbohidrat yang digunakan pada penelitian ini berasal dari Lemna minor (Duckweed). Penelitian ini bertujuan membuat bioetanol dari Lemna minor dengan variasi penambahan ragi dan lamanya waktu fermentasi. Kemudian bioetanol ini ditentukan kadar etanol dan densitasnya serta mengetahui hubungan antara keduanya. Produksi bioetanol telah dilakukan melalui proses konversi karbohidrat menjadi gula (glukosa) dengan hidrolisis asam (HCl).Hidrolisat yang diperoleh selanjutnya dilakukan fermentasi dengan menambahkan yeast atau ragi sehingga diperoleh bioetanol. Variabel yang digunakan adalah perubahan massa ragi 5%,15%, dan 25% serta lama fermentasi 5, 6, dan 7 hari . Hasil penelitian menunjukkan lama fermentasi dan persentase ragi mempengaruhi kadar etanol. Nilai kadar etanol optimum diperoleh presentase ragi 25% dengan lama fermentasi 7 hari sebesar 3.81% dengan density optimum sebesar 0.9438 gr/cm 3, Hubungan nilai densitas berbanding terbalik dengan peningkatan kadar etanol.Kata kunci: Persentase ragi; waktu fermentasi; Lemna minor.
ABSTRACT:One alternative in favor of the availability of renewable energy resources is to utilize non-fossil sources such as bioethanol. Bioethanol is ethanol made from biomass component containing starch (carbohydrate) or cellulose. Furthermer it is fermented using microorganisms (Sacharomyces cerevisiae). In this study Lemna minor (Duckweed) was used to produce carbohydrates . This study aims is to make bioethanol from Lemna Minor with percentage of yeast and length of fermentation time in variation. It is then determined the ethanol value, density and the relation between them. Bioethanol production was conducted through the process of converting carbohydrates into sugar (glucose) by acid hydrolysis (HCl). Hydrolysates were then fermented by adding yeast to obtain bioethanol. The used variables were yeast mass 5%, 15%, and 25% and fermentation time 5, 6, and 7 days. The results pointed out that the percentage of yeast and fermentation time affect the levels of ethanol. The optimum ethanol value obtained by 25% ethanol with 7 days fermentation lenght was 3.81%. While optimum density was 0.9438 g / cm 3. The relation between ethanol value and density are inversely proportional.
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