Judul: Development of Portable Photometer for Quality Qontrol of Temulawak Rhizome (Curcuma xanthorriza).
Abstrak: Temulawak (Curcuma xanthorriza) is one of medicinal plants grown and used as a medicine in Indonesia. A good medicine requires temulawak with good quality, which is determined by its chemical composition. The diversity of chemical components of temulawak can be determined using spectroscopic methods. The purpose of this research is to develop portable photometer as instrument for quality control of temulawak rhizome by evaluating the quality based on the different harvesting age and combined with pattern recognition using principle component analysis (PCA) and partial least square discriminant analysis (PLSDA). Temulawak rhizomes with different plant ages (6, 7, 8, and 9 months) were measured using a portable photometer, and then combined using PCA and PLSDA techniques. The results showed that temulawak rhizomes from different ages were readily distinguished. PCA analysis using two main components: PC 1 = 66% and PC 2 = 21%. For the analysis of values obtained PLSDA R2 close to 1 and root mean square error of prediction (RMSEP) close to 0, and also it produced 4 models (6, 7, 8, and 9 months). Quality of the rhizomes samples 7, 8, 9 month declined at prolonged storage. This was due to decreased levels of active chemical compounds contained in the rhizome samples.
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Judul: The Development of Reflectance Spectrophotometer and Chemometric for Discriminating Temu Lawak and Turmeric
Abstrak: Identitas suatu bahan dapat ditunjukkan melalui spektrum reflektansnya yang didapatkan dari hasil interaksi antara radiasi UV-Vis dan molekul kimia dalam sampel. Penelitian ini bertujuan mengembangkan spektrofotometer berbasis reflektans dengan menggunakan komponen-komponen alat yang mudah didapatkan. Penggunaannya yang dikombinasikan dengan analisis kemometrik digunakan sebagai diskriminasi temu lawak dan kunyit. Spektrofotometer dirakit dengan lampu light emitting diode (LED) sebagai sumber radiasi, lapisan optik digital versatile disk (DVD) sebagai kisi difraksi, web camera sebagai detektor, dan akuisisi data menggunakan peranti lunak theremino spectrometer. Spektrum reflektans temu lawak lebih tinggi dibandingkan dengan kunyit. Data spektrum reflektans yang didapat pada daerah 400.3600.2 nm telah diberi perlakuan pendahuluan berupa transformasi variat normal standar sebelum diolah dengan principal component analysis (PCA). Sampel dapat dikelompokkan dengan cukup baik menggunakan metode PCA dan komponen utama dapat memberikan informasi sebesar 71% dari total varians., The identity of a material can be shown by its reflectance spectrum obtained from the interaction between UV-Vis radiation and chemical molecules in the sample. This study aims to develop a reflectance-based spectrophotometer using readily available components. Its use in combination with chemometric techniques is used to discriminate between temu lawak (Curcuma xanthorrhiza) and turmeric. The spectrophotometer was constructed of a light emitting diode (LED) lamp as a radiation source, a digital versatile disk (DVD) optical layer as a diffraction grating, a web camera as a detector, and data acquisition using the Theremino spectrometer software. Furthermore, a spectrophotometer was used to discriminate between temu lawak and turmeric. Reflectance spectrum of temu lawak is higher than turmeric. The reflectance spectrum data obtained in the 400.3600.2 nm region has been preprocessed in standard normal variate transformation before being processed using principal component analysis (PCA). As a result, the sample can be grouped well using the PCA method, and the principal components can provide information of 71% of the total variance.
Keyword: curcuma, discrimination, principal component analysis, reflectance spectrophotometer, turmeric

Judul: Sifat operasi dan eksistensi invers suatu matriks dalam aljabar max-plus
Abstrak: Karya ilmiah ini membahas sifat-sifat operasi dalam aljabar max-plus dan sifat-sifat yang diaplikasikan pada matriks serta eksistensi invers matriks dalam aljabar max-plus. Operasi-operasi matriks yang dapat diaplikasikan dalam aljabar max-plus meliputi operasi penjumlahan dan perkalian antar matriks, matriks transpose, matriks identitas, matriks segi pangkat ke-k, serta perkalian matriks dengan skalar. Sifat- sifat yang berlaku untuk matriks dalam aljabar max-plus yaitu sifat asosiatif (untuk operasi penjumlahan dan perkalian), komutatif (hanya untuk operasi penjumlahan), dan distributif. Eksistensi invers suatu matriks a ∈ dalam aljabar max-plus dapat dipastikan ada jika dan hanya jika a merupakan perkalian matriks permutasi dan matriks diagonal . Max nxn p ( ) i d 
Keyword: matriks, aljabar max-plus