Judul: Pengembangan Prototipe Sistem IoT Monitoring Hidroponik NFT Berbasis ESP8266
Abstrak: Budidaya hidroponik dapat dilakukan pada lahan terbatas, cuaca ekstrim, dan persedian air terbatas. Namun agar budidaya hidroponik berhasil, perlu diperhatikan aspek kualitas larutan nutrisi berupa nilai TDS, pH, debit aliran, suhu lingkungan, dan lain-lain. Penelitian ini bertujuan untuk mengembangkan sistem IoT pemantau hidroponik nutrient film technique (NFT) dengan sensor pH, TDS, suhu, aliran dan ketinggian larutan nutrisi; serta suhu lingkungan, kelembapan, dan intensitas cahaya. Sistem ini menggunakan mikrokontroler Wemos D1 mini ESP8266 dengan tambahan modul ADS1115. Penelitian dilakukan dalam lima tahap yaitu analisis kebutuhan, desain prototipe, interfacing sensor, integrasi, dan pengujian lapang. Penelitian ini berhasil mengembangkan prototipe sistem IoT pemantau hidroponik NFT berbasis ESP8266 dengan tujuh jenis sensor yang telah disebutkan di atas. Data pemantauan dikirim ke platform IoT ThingSpeak secara real time.
Keyword: ESP8266, hydroponics, IoT, monitoring, NFT

Judul: Rancang Bangun Sistem Monitoring dan Controlling Nutrisi Tanaman untuk Hiroponik.
Abstrak: Nutrisi pada budidaya tanaman dengan sistem hidroponik sangat menentukan kondisi dan pertumbuhan tanaman. Nutrisi yang telarut dalam air dipengaruhi oleh nilai elektroconductivity (EC), potensial hidrogen (pH) serta kondisi lingkungan berupa suhu dan kelembaban. Tujuan dari penelitian ini adalah merancang bangun dan menguji kinerja sistem monitoring suhu dan kelembaban lingkungan, serta menguji kinerja sistem kontrol nilai EC, nilai pH, dan ketinggian level air pada nutrisi sistem hidroponik tipe NFT. Microcomputer Raspberry Pi dan microcontroller Arduino dipilih sebagai controller utama. Kebutuhan nutrisi diatur pada tingkat pertumbuhan awal tanaman, dengan umur tanaman 2 – 10 hari. Level muka air di atur pada jarak 10 cm dengan volume tangki terisi sebanyak 218 liter. Nilai EC yang dibutuhkan pada nutrien sebesar 1000 – 1200 μS/cm dengan pH 5.5 – 7.0. Rentang nilai yang digunakan mengacu pada model yang diterapkan di greenhouse Sabisa Farm IPB. Hasil monitoring suhu dan kelembaban menunjukkan suhu lingkungan berkisar antara 24 - 28oC dan kelembaban 70 - 90%. Nilai EC dan pH berubah-ubah sehingga perlu dilakukan pengontrolan. Ketika nilai EC dibawah setpoint 1000 μS/cm maka pompa menyala selama 7 detik untuk menambahkan nutrisi AB mix sebanyak 109 ml. Penambahan akan membuat nilai EC kembali meningkat menjadi sekitar 1200 μS/cm. Sedangkan nilai pH berada pada range angka yang ditetapkan sehingga tidak dilakukan penambahan larutan asam. Hasil pengujian menunjukkan monitoring dan sistem kontrol dapat berjalan dengan baik sesuai setting yang dilakukan.
Keyword: arduino, controlling, hidroponik, monitoring, nutrisi, raspberry pi

Judul: The Effects of Variance of Interest rate to Variance of Annuity Future Values
Abstrak: Time value of money is a concept that refers to the difference of the value of money due to time difference. The value of money for present time would not be the same as the value of money in the future. The value of money for present time is called as Present Value (PV) of the money and the value of money for future time is called Future Value (FV) of the money. Determination the value of money, for present and future time, depends on the time and rate of return. The value of money is determined by several factors such as inflation, fluctuation of interest rates, and government policy in securities and taxation. Due to fluctuation of the value of money we need a FV formulation, it is useful for knowing whether an investment can be profitable or not, and this information is useful also in budget analysis. Annuity is defined as a series of payments made for a specific period. The payment, fixed or varied, can be made at the beginning or at the end of the period. Annuity paid at the beginning of the period is called annuity-due and annuity paid at the end of the period is called immediate annuity-certain. The accumulated value of the annuity after few years later is called as a final value or a future value. Burnecki et al. (2003) have discussed about the FV of a fixed-rate annuity in which payments are made according to the arithmetic or geometric series. They have also examined FV for annuities in which payments are made according to arithmetic or geometric series with random rates of interest. This paper examines FV for annuity-due in which payments are made according to arithmetic or geometric series with interest rates as a random variable, which is normal distribution ,  . Future value formula is expressed in recursive form. FV for annuity-due which payments are made according to the arithmetic or geometric series with random rates of interest is calculated by theoretical way and simulation way. The random rates of interest is denoted as k k i  i  , where k i an independent random variable; i is a constant and k  is a random variable which has normal distribution ,  . By using the determined parameters, a sequence of random rates of interest are generated for theoretical calculation. Meanwhile for the simulation, the random rates of interest is generated 1000 times for the simulation. The generated data give mean value, variance, and standard deviation. Moreover, error of mean value, variance, and standard deviation from the theoretical and simulation results are calculated. Error calculation uses Symmetric Mean Absolute Percentage Error (SMAPE). The smaller the value of SMAPE is the more accurate the simulation. The interest rate variances are varied from 0.000036 to 0.0001 to study the relationship between variance of rates of interest and variance of future value. The theoretical and simulation results show that when the variance of random rates of interest increases, then the variance of FV increases linearly. FV of the annuity-due in
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