Judul: Estimation of Sweetness and Firmness Values of Grape Fruit using NIRS (Near Infrared Spectroscopy)
Abstrak: Anggur merupakan buah non klimaterik, yaitu buah yang pola respirasinya menurun dan tidak menunjukkan adanya kenaikan konsumsi O2 dan produksi CO2 yang mencolok. Hingga saat ini penentuan tingkat kematangan buah anggur masih dilakukan berdasarkan pengamatan visual tanpa bantaun alat. Oleh karena itu jika buah anggur dipanen belum cukup umur, maka akan mempunyai kualitas yang rendah karena belum matang sempurna. Deteksi tigkat kematangan yang cepat dan efisien dapat diwujudkan melalui penggunaan teknologi Near Infrared Spectroscopy (NIRS). Penelitian ini bertujuan mempelajari karakteristik kematangan buah anggur melalui parameter total padatan terlarut (TPT) dan kekerasan serta spektrum NIRS dari buah anggur dengan umur panen yang berbeda serta mengembangkan model kalibrasi untuk prediksi nilai TPT dan kekerasan berdasarkan reflektan spektra NIR meggunakan metode PLS. Sampel yang digunakan yaitu 240 buah anggur dengan tiga umur petik yang berbeda yaitu masing-masing 85, 90, dan 95 hari setelah bunga mekar (HSBM). Pengukuran reflektan buah anggur dilakukan menggunakan alat spektrometer NIRFlex N-500 fiber optic solid. Pengukuran total padatan terlarut dan kekerasan secara destruktif dilakukan menggunakan rheometer dan refraktometer. Kalibrasi data NIRS dan data total padatan terlarut serta kekerasan dilakukan menggunakan Partial Least Square (PLS) untuk mendapatkan model kalibrasi terbaik dalam memprediksi total padatan terlarut dan kekerasan. Pendugaan total padatan terlarut terbaik diperoleh melalui spektrum reflektan dengan pra-pengolahan data menggunakan Three points Smoothing Avarage pada faktor PLS 17 (r = 0,83; standard error calibration (SEC) = 0,47 %brix; standard error prediction (SEP) = 0,44 %brix; ratio of standard error prediction to deviation (RPD) = 1,89; konsistensi = 108,66 %). Pendugaan kekerasan terbaik diperoleh melalui spektrum reflektan original atau tanpa pra-pengolahan data dengan faktor PLS 14 (r = 0,89; standard error calibration (SEC) = 0,98 N; standard error prediction (SEP) = 1,04 N; ratio of standard error prediction to deviation (RPD) = 2,06; konsistensi = 94,33 %)., Grapes are non-climacteric fruits, meaning that the fruits whose respiration pattern decreases and does not show a significant increase in O2 consumption and CO2 production. Until now, the determination of the level of ripeness of grapes is still conducted based on visual observations without the help of tools. Therefore, if the grapes are harvested not yet old enough, they will have low quality because they are not yet fully ripe. Fast and efficient detection of ripeness levels can be realized through the use of Near Infrared Spectroscopy (NIRS) technology. This study aims to study the maturity characteristics of grapes through the parameters of total dissolved solids (TSS) and nirs hardness and spectrum of grapes with different harvest ages and develop a calibration model for the prediction of TSS values and hardness based on reflectance of NIR spectra using the PLS method. The samples used were 240 grapes with three different picking ages, namely 85, 90, and 95 days after blooming. The reflectance measurement of grapes was carried out using a solid fiber optic NIRFlex N-500 spectrometer. Measurements of total dissolved solids and firmness were destructively carried out using a rheometer and refractometer. Calibration of NIRS data and data on total dissolved solids and firmness were performed using Partial Least Square (PLS) to obtain the best calibration
Keyword: total dissolved solid, Firmness, Partial Least Square, Three-points Smoothing Average

Judul: Estimation of Physico-chemical Characteristics of Apple Fruit Using Near Infrared Spectroscopy
Abstrak: Apel (Malus sylvestris.) merupakan buah yang memiliki nilai ekonomi cukup tinggi di Indonesia. Apel banyak digemari oleh masyarakat Indonesia karena memiliki cita rasa yang khas dan menimbulkan efek segar pada orang yang mengonsumsinya. Cita rasa apel terbaik diperoleh ketika buah sudah matang sempurna dan apel merupakan buah klimaterik sehingga tingkat kematangan dipengaruhi oleh ketuaan buah saat dipanen. Namun penentuan ketuaan apel masih dilakukan secara visual tanpa alat bantu sehingga hasilnya kurang akurat, kurang objektif sehingga berpotensi kematangan tidak sempurna. Metode spektroskopi NIR (Near Infrared Spectroscopy) memberikan alternatif dalam menentukan tingkat ketuaan buah apel tanpa merusak bagian buah tersebut. Penelitian ini bertujuan untuk menduga sifat fisiko-kimia buah apel manalagi dengan tiga umur panen berbeda (130, 140, dan 150 hari setelah bunga mekar, HSBM) secara nondestruktif dengan menggunakan metode spektroskopi NIR. Sifat atau kandungan fisiko-kimia buah apel terkait dengan tingkat ketuaan buah apel. Parameter yang diuji untuk menentukan kandungan fisiko-kimia buah apel adalah total padatan terlarut, kekerasan daging, dan kadar air. Hasil penelitian menunjukkan hasil terbaik untuk pendugaan total padatan terlarut buah apel didapatkan menggunakan pra-pengolahan data Smoothing Savitzky-Golay (SGs) dengan nilai koefisien korelasi sebesar 0.93; standard error of calibration (SEC) sebesar 0.81 %brix; standard error of prediction (SEP) sebesar 0.86 %brix dan ratio of standard error of prediction to deviaton (RPD)sebesar 2.61. Untuk parameter kekerasan buah hasil terbaik didapatkan dengan pra-pengolahan data Multiplicative Scatter Correction (MSC) dengan nilai koefisien korelasi sebesar 0.78; SEC sebesar 0.47 N; SEP sebesar 0.45 N dan RPD sebesar 1.53. Untuk parameter kadar air didapatkan hasil terbaik dengan pra-pengolahan data Standard Normal Variate (SNV) dengan nilai koefisien korelasi sebesar 0.75; SEC sebesar 0.92%; SEP sebesar 0.85% dan RPD sebesar 1.50., Apple (Malus sylvestris.) is a fruit with high economic value in Indonesia. Apples are much favored by people in Indonesia because they have a distinctive taste and have a fresh effect on people who consume them. The best apple taste is obtained when the fruit is fully ripe and the apple is a climacteric fruit so that the level of maturity is influenced by the age of the fruit when it is harvested. However, the determination of the aging of apples is still done visually without any tools so that the results are less accurate, less objective so that the potential for ripeness is not perfect. The NIRS (Near Infrared spectroscopy) method provides an alternative to determine the level of maturity of apples without damaging the fruit. This study aims to estimate the physico-chemical properties of manalagi apples with three different harvest ages (130, 140, and 150 days after blooming, DAB) nondestructively by using the NIR spectroscopy method. The properties or physicochemical properties of apples are related to the level of maturity of apples. The parameters tested to determine the physico-chemical content of apples were total dissolved solids, flesh hardness, and moisture content. The results showed that the best results for estimating total soluble solids of apples were obtained using Smoothing Savitzky-Golay (SGs) data pre-processing with a correlation coefficient of 0.93; standard error of calibration (SEC) of 0.81 %brix; standard error of prediction (SEP) is 0.86 %brix and ratio
Keyword: Apple, flesh hardness, moisture content, NIRS, total dissolved solids

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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