Judul: Deteksi Gejala Kerusakan Dingin pada Buah Mangga Varietas Gedong Gincu (Mangifera indica, L.) yang Disimpan pada Suhu Rendah Menggunakan NIR
Abstrak: Low temperature storage is common method to maintain the self life of fruits. However, for some fruits, low temperature storage may cause chilling injury. Chilling injury will cause the quality of fruits becomes lower. Detection of chilling injury symtopms of fruits during storage at low temperature is important in order to minimize the effect of low temperature on the quality of fruits. Change in ion leakage of fruits during storage period is one of the method to predict the chilling injury symptoms. However, this method is destructive method and the measurement time is quite longer. Generally the objectives of this study was to determine the quality of mango fruit namely total soluble solid and firmness as indicator of chilling injury non destructively using NIR and artificial neural network. Experimental temperature storage was set at 8oC. During storage period, total soluble solid, NIR spectra, firmness and ion leakage was measured every 2 days. Ion leakage was calculated based on the data of changes on the electro conductivity of sample of mango.Chilling injury symptom was determined from the changes in slope obtained from linear regression equation. It was found that the highest slope was at days 4 with the value of 0.174. At days 4, the measurement of total soluble solid and firmness were 8.2 oBrix and 3.80 kgf respectively. Model of artificial neural network 11-10-1 was used to predict the total soluble solid and 11-8-1 for the firmness. The difference value of mean square error (MSE) calibration and validation was 2.85% with a coefficient of variation (CV) of 11.6% for calibration and 19.1% for validation. Prediction of firmnesss was 0.22 with a CV of 32% for calibration and 27.7% for validation. Model prediction of firmness was not good to be used because of the large CV resulted. Estimate value of model of monitoring fruit parameters after 4 days of storage was 11.9 oBrix for TPT and 0.40 kgf for firmness. The value indicated monitored fruits had already passed the phase of mature green so chilling injury symptoms could not be detected.
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Judul: Deteksi Chilling Injury pada Buah Mangga Gedong Gincu dengan Menggunakan Near Infrared Spectroscopy (NIRS)
Abstrak: Low temperature storage is a common method to extend postharvest life of fruits. However, for sensitive fruits such as mango low temperature storage may cause chilling injury. Chilling injury is one of serious problem for mango stored under low temperature. The symptoms of chilling injury during storage associated with the change in pH due to ion leakage. Chilling injury can be detected during storage destructively, but it will require time and a lot of samples. Alternatively, the detection can be performed non-destructively by using near infrared (NIRSpectroscopy). The purpose of this research is to build the NIR calibration models for predicting ion leakage relating to change in pH and the detection of chilling injury symptoms can be done through ion leakage existence. Reflectant NIR measurements conducted on mango fruit stored at a temperature of 8 °C and 13 °C. Determination of chilling injury symptoms was predicted based on change in pH and the rate of ion leakage forming. The analysis showed that NIR spectroscopy was able to predict the change in pH during storage of mango fruit at a temperature of 8 °C based on reflectance and PLS method. Moreover ion leakage could also be predicted properly through the pH of the NIR predictions. The developed method could detect the chilling injury on mangoes after three days storage at a temperature of 8 °C.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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