Judul: Optimization of Pressing Temperature and Time of Composite Molding of Sweet Sorghum Bagasse with  Sucrose-Based Adhesive
Abstrak: Moulding komposit yang ramah lingkungan diperlukan pada produk yang digunakan dalam kehidupan manusia sehari-hari seperti kitchen set, komponen kendaraan, bagian bangunan, dll. Oleh karena itu, bagas sorgum sebagai limbah perkebunan sorgum dan perekat asam sitrat-sukrosa merupakan salah satu sumber daya berkelanjutan yang dapat digunakan sebagai bahan baku pembuatan moulding. Akan tetapi, kondisi kempa yang optimum dalam pembuatan moulding bagas sorgum yang direkat dengan asam sitrat-sukrosa belum diketahui. Oleh karena itu, suhu dan waktu kempa optimum diselidiki. Variasi suhu dan waktu pengempaan masing-masing adalah 180, 200, 220 ºC dan 8, 10, dan 12 menit. Hasil penelitian menunjukkan bahwa kekuatan lentur dan stabilitas dimensi moulding meningkat dengan meningkatnya suhu pengempaan. Moulding dengan kondisi pengempaan panas 200 ºC dan 12 menit memiliki nilai MOE (2,86 Gpa) dan MOR (16,70 Mpa) lebih tinggi daripada kondisi pengempaan lainnya. Dengan demikian, 200 ºC dan 12 menit masing-masing adalah suhu dan waktu kempa yang optimum., Eco-friendly moulding composite is necessary in all products which is used in daily life of human being such as kitchen set, body part of vehicle, building part, etc. Therefore, sorghum bagasse as a waste of sorghum plantation and sucrose-citric acid as one of the sustainable resources were used as raw material of the moulding. However, the optimum of pressing condition in the manufacturing of sorghum bagasse moulding bonded with sucrose-citric acid does not determine. Therefore, the optimum of pressing temperature and time were investigated. The variation of pressing temperatures and time were 180 ºC, 200 ºC, 220 ºC and 8, 10, and 12 minutes, respectively. The results showed that the bending strength and dimensional stability of the moulding increased with increasing the pressing temperature. The moulding with 200 ºC and 12 minutes of hot pressing condition has the MOE (2.86 Gpa) and MOR (16.70 Mpa) higher than those of the other pressing condition of the moulding. Thus, 200 ºC and 12 minutes were pressing temperature and time optimum, respectively.
Keyword: Asam sitrat, Moulding, Suhu kempa, Sukrosa, Waktu kempa, Citric acid, Molding, Pressing temperature, Pressing time, Sucrose

Judul: Optimasi Proses Pembuatan Mi Sorgum Kering dengan Menggunakan Ekstruder Ulir Ganda
Abstrak: The Objective of this research was to optimize two processing variable i.e. extruder temperature (80, 85, and 90 oC) and screw speed (10, 15, and 20 Hz). The optimum process was chosen using Response Surface Method (RSM) in Design Expert 7.0 software. Optimization using response surface method (RSM) were based on 7 parameters, i.e., cooking loss, elongation, hardness, cohesiveness, gumminess, chewiness, and springiness. Result of this research showed that the optimum processing condition with desirability of 0.551, was resulted from the combination of the extruder temperature 85 oC and screw speed 10 Hz. The verification showed that the sorghum noodles from this optimum condition had cooking loss of 12.87 %, elongation of 234.84 %, hardness of 2094.82 gf, cohesiveness of 0.597, gumminess of -37.25 gf, chewiness of 33.492 gf, and springiness of 0.899
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Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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