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In this paper, we determine equitable irregular chromatic number of Jelly Fish J(m, n) and coconut tree graph CT(n, n).

Indonesia is the largest coffee exporter in the world, which is in the fourth position after Brazil, Vietnam and Colombia. However, the productivity of coffee produced from year to year tends to decrease and not optimal. This happens because of many factors, one of which is the type of shade plants used. Inappropriate shade plants affect the growth and productivity of coffee plants. The purpose of this research was to analyze the utilization of Gamal plant (Gliricidia sepium) as a shade for coffee plants. The respondents of this research were 35 coffee farmers in Jember and Banyuwangi regencies. The research variables measured included the types of coffee shade plants, reasons for using shade plants and farmers' knowledge about Gamal plant as a shade for coffee plants. The data collection was carried out using survey, interview and questionnaire. The data collection was done directly with the primary source. The results of this research informed that the shade plants used by coffee farmers were varied, such as banana, lamtoro, coconut tree, Gamal, avocado and sengon trees. Most of the coffee farmers used bananas by 86%, avocados by 65%, and wood by 46% as a shade. They chose the plants because they were easier to maintain, cheap seeds and produced fruit and woods which could be sold. Based on the literature, the most effective shade plants for coffee plants were Gamal plants. However, Gamal plant (Gliricidia sepium) is still not widely used by coffee farmers because the seeds are too expensive and it does not produce fruit that can be sold. The conclusion of this research was that most of the coffee farmers were still unaware and did not use Gamal as a shade plants.

An investigation of how coconut palm tree withstands gale force winds has been performed. When observed carefully, the motion of the stalks and leaves affected the wind resistance. The stalks and leaves move randomly when the wind blows continously. Although this is such an interesting phenomenon, there is still no report on the physical modelling. This paper proposes a simple mathematical model to analyze the phenomenon. A simple tool was also designed to retrieve data usingVideo Tracker. The experiments were conducted on several types of springs. The model showed that the theoretical prediction accurately explained the phenomenon.