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"Sumber daya alam banyak sekali digunakan dalam sintesis senyawa organik. Keterbatasan sumber daya alam yang tersedia menyebabkan pemakaian sumber daya alam beralih ke sumber daya alam yang dapat diperbaharui. Biomassa adalah sumber daya terbaharui yang dapat dihidrolisis untuk menghasilkan senyawa organik bernilai tinggi seperti asam levulinat. Hidrolisis biomassa pertama-tama akan menghasilkan antara lain glukosa yang selanjutnya terhidrolisis menghasilkan senyawa asam levulinat dan asam format. Pada penelitian ini dilakukan hidrolisis glukosa dengan katalis homogen (H2SO4), katalis heterogen (γ-Al2O3/SO4 2-), dan tanpa katalis sebagai pembanding. Katalis heterogen yang digunakan disintesis dari scrap aluminium kemudian dikarakterisasi dengan XRD, XRF, BET, dan FT-IR. Reaksi hidrolisis dilakukan pada suhu 140 ºC dengan variasi waktu yaitu 2 jam, 4 jam, dan 6 jam untuk reaksi dengan katalis homogen; 4 jam, 6 jam, dan 8 jam untuk reaksi dengan katalis heterogen dan reaksi tanpa katalis. Hasil hidrolisis dianalisis dengan HPLC. Dari hasil penelitian ini didapatkan asam levulinat pada reaksi hidrolisis 6 jam dengan katalis homogen sebanyak 2,93% . Untuk produk reaksi katalisis dengan γ-Al2O3/SO4 2- hanya dapat ditentukan banyaknya asam format yang terbentuk, sedangkan asam levulinat tidak terdeteksi karena teradsorpsi pada padatan katalis.

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A lot of natural resources are used in the synthesis of organic compounds. Since the availabilities of some natural resources are limited, they are now replaced by the renewable resources. Renewable natural resources such as biomass can be hydrolyzed to produce high added-value organic compounds. At first, biomass is hydrolyzed to produce glucose and then is further hydrolyzed to produce levulinic acid and formic acid. In this research, the hydrolysis of glucose was conducted using sulfuric acid as homogeneous catalyst and γ-Al2O3/SO4 2- as heterogeneous catalyst. As a comparison, the hydrolysis reaction was also conducted without catalyst. The γ-Al2O3/SO4 2- catalyst was first synthesized from aluminium scraps and was characterized by XRD, XRF, BET, and FT-IR. The hydrolysis reactions were carried out at a temperature of 140 ºC and the reaction periods were varied 2 hours, 4 hours, and 6 hours for the homogeneous catalytic; 4 hours, 6 hours, and 8 hours for the heterogeneous catalytic reaction and the reaction without catalyst. The hydrolysis products were analyzed by HPLC. From the result of this study, 2,93% levulinic acid was produced after 6 hours in the hydrolysis reaction with sulfuric acid. By using heterogeneous catalyst only formic acid can be detected because of adsorption levulinic acid on the catalyst."

"This book presents several aspects of research on mathematics that have significant applications in engineering, modelling and social matters, discussing a number of current and future social issues and problems in which mathematical tools can be beneficial. Each chapter enhances our understanding of the research problems in a particular an area of study and highlights the latest advances made in that area. The self-contained contributions make the results and problems discussed accessible to readers, and provides references to enable those interested to follow subsequent studies in still developing fields. Presenting real-world applications, the book is a valuable resource for graduate students, researchers and educators. It appeals to general readers curious about the practical applications of mathematics in diverse scientific areas and social problems."

"ABSTRAKDalam tulisan ini dibahas beberapa kriteria osilasi persamaan diferensial linier homogen orde dua x''(t)+m(t)x'(t)+n(t)x(t)=0 , dimana m,n fungsi kontinu pada [0,∞). Kriteria osilasi persamaan ini tergantung dari fungsi m dan n yang diberikan. Jika m dan n fungsi sembarang asalkan kontinu pada [0,∞) maka dapat digunakan bentuk normal dari persamaan diferensial linier homogen orde dua dan jika fungsi m bernilai negatif maka kriteria osilasi ditentukan dengan beberapa syarat tertentu.

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ABSTRACTIn this thesis we discuss some oscillation criteria for homogenous second order linear differential equations x''(t)+m(t)x'(t)+n(t)x(t)=0, where m,n continuous functions on [0,∞). Some oscillation criteria of this equations are dependent from function m and n. If m and n any continuous function on [0,∞) can be used then normal form of homogenous second order linear differential equations and if function m is negative then the criteria of oscillation is determined by certain conditions."

"This paper explains the development of a parallel computing platform using the available LAN at the Inter University Center for Computer Science of Indonesia. A software toll like parallel virtual machine enables the networked stations to be harnessed as a huge computing resource, combining various type of computing nodes to run parallel computing tasks. The research was aimed at first: to develop a number of parralel high complexity algorithms such as modelling air pollution distribution based on Gaussian Air Pollution Dispersion Formula which simulates dispersion of pollutant emiotted from industrial exhaust and also from vehicle exhaust ont the road. Secondly these algorithms were used to test the platform to obtain networkd behaviour in supporting the implementation of parallel algorithms. From the experiments conducted there are strong indications that the network based computing facility could be used as a suitable platform for running parallel programs with some restrictions. Optimum performance with near linear speed up could be obtained by carefully partitioning the problems, limiting message passing activities and balancing the load of the participating processors."