Judul: Analisis Pindah Panas pada Pipa Pendingin untuk Zone Cooling dalam Sistem Hidroponik
Abstrak: Pada siang hari ketika cuaca cerah, air yang didinginkan dengan chiller di dalam zone cooling system untuk daerah perakaran dalam budidaya tanaman secara hidroponik mengalami kenaikan suhu sepanjang pipa pendingin. Pindah panas terjadi sepanjang pipa pendingin, dari daerah perakaran ke pipa pendingin. Analisis pindah panas sepanjang pipa pendingin tersebut adalah sangat penting dalam perancangan zone cooling system tersebut. Tujuan dari penelitian ini adalah (1) melakukan analisis pindah panas pada pipa pendingin untuk zone cooling dalam sistem hidroponik, (2) melakukan validasi model pindah panas untuk memprediksi suhu air pada posisi outlet pipa pendingin, dan (3) melakukan simulasi komputer untuk berbagai bahan pipa dan panjang pipa untuk beberapa kondisi termal rumah tanaman. Model pindah panas telah dikembangkan dari persamaan-persamaan pindah panas dan aliran fluida didalam pipa. Validasi model pindah panas dilakukan dengan membandingkan angka suhu air hasil prediksi dengan hasil pengukuran dalam grafik regresi linear. Hasil validasi menunjukkan bahwa model pindah panas tersebut dapat digunakan untuk memprediksi suhu air pendingin pada posisi outlet pipa pendingin. Model pindah panas tersebut dapat digunakan dalam pemilihan bahan dan ukuran pipa serta penentuan jarak antar pipa pendingin.
Keyword: Hydroponics, Heat transfer analysis, Root zone cooling, Water flowing, Cooling pipe, Hydroponic culture, Cooling system, Transfer model, Water temperature, Computer simulation

Judul: Analisis Pindah Panas pada Pipa Utama Sistem Hidroponik Substrat dengan Pendinginan Larutan Nutrisi
Abstrak: Cooled nutrient solution will have temperature rises during distributed to the root zone of the plants. The aim of the research was to analyze the heat transfer from environment to the main pipe of irrigation for hydroponic substrate system, to validate the heat transfer model, and to simulate inlet temperature for nutrient solution cooling planning. Heat transfer model was developed from heat transfer and fluid flow in pipe equations. Validation of heat transfer model was done using linear regression analysis method. Simulation was done by calculating temperature of inlet nutrient solution which is proper to get optimum temperature for plants using validated heat transfer model. The result of heat transfer model validation showed that the heat transfer model is fairly accurate to predict the temperature of nutrient solution in the main pipe. The simulation result showed that to obtain 20 °C temperature of nutrient solution at the end of ¾ inch PVC uninsulated main pipe with a length of 20 m, the inlet nutrient solution must be cooled to temperature of 18.06 °C.
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Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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