| Nama Pengarang | : | Setyawan Widyarto |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 141-149 |
| Abstraksi Narasi | : | Paper ini menyajikan sifat-sifat rheology ABS Lustran QE 1455. Sifat-sifat yang diteliti meliputi shear rate on viscosity, effect of shear stress on viscosty, dan proses dilakukan secara terpisah. Data diambil dari penelitian yang dilakukan Laboratorium Polyme, the University of Bradford, England. Pecobaaan menggunakan Rosand RH7 untuk mengukur off-line rheometry. Shear stress sebagai fungsi dari shear rate disajikan dalam grafik dan terlihat bahwa grafik membentuk kurva yang berbentuk cekung ke bawah. Perilaku shear stress meningkat apabila shear rate meningkat seperti terlihat dalam grafik itu. Viscosity sebagai fungsi dari shear rate diplotkan dalam beberapa temperatur yang berbeda. Penurunan viscosity terjadi saat peningkatan shear rate seperti ditunjukkan dalam grafik yang lain. Perilaku ini disebut aliran pseudoplastic. Pada shear rate yang sama, grafik menunjukkan implikasi bahwa semakin tinggi tempertaur semakin rendah shear viscosity. |
| Nama Pengarang | : | M.Sastrapratedja |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 97-108 |
| Abstraksi Narasi | : | During the last two decades there has been an increasing interest in the ethics of natural sciences and technology. The potential power of science and technology has been multiplied as to be able to change the condition of life and the course of evolution, to alleviate human sufferings and to create more prosperous society. However, the risk is also potentially great. The question is whether we ought to do everything we can do? Ethics has the task to make a judgement about what is "good" or "bad" as orientation towards action. Ethical implications of biology and biotechnology, computer and engineering are examined in this article. |
| Nama Pengarang | : | I. Deradjad Pranowo |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 163-169 |
| Abstraksi Narasi | : | Open CNC adaah sistem kontrol mesin CNC (Computer Numerical Control) berbasis software yang dibuat berdasarkan konsep OAC (Open Architecture Control) dalam satu aplikasi menjadikan Open CNC cocok sebagai satu perangkat baru yang sama baiknya dengan sistem kontrol hardware produksi dari vendor mesin CNC itu sendiri. Open CNC memberikan solusi pergantian sistem kontrol yang tidak didapatkan dalam teknologi kontrol CNC tradisional. Dengan kontrol CNC berbasis software diharapkan mesin CNC menjadi tidak lagi tergantung sepenuhnya pada produsen sistem kontrol/komponen dari Vendor tertentu dan sekaligus mengurangi beaya produksi. |
| Nama Pengarang | : | Santoso, Agus, Darsono, Uminingsih, I. Deradjad Pranowo, M. Sastrapratedja, Setyawan Widyarto, Kadarwati Budihardjo, Etty Sumiati, I Gusti Ketut Puja, Mudjijana, Tjipto Suyitno, Damar Wijaya, Hanoch J. Sohilait, A. Bayu Primawan, Reny Kusumastuti |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 127-133 |
| Abstraksi Narasi | : | A fast non-destructive soil moisture gauge using neutron reflection has been developed. The main components of this device are AmBe 10 pangkat 3 n/s neutron source, He-3 proportional defector, aluminium container, counter, and peraffin neutron shielding. The basic operation of this gauge is based on the difference of slow neutron counts with and without water samples. It is based on the fact that neutron is slowed down more effectively by hydrogen atom than by others. The experimental performance test shows that the constructed gauge has sensitivity of 7 counts / % wt of moiture measurenment accuracy of 16% for dry soil and 3.5% for wet soil, and reproductibility of 97% for wet soil and 84% for dry soil. |
| Nama Pengarang | : | Agnes Maria Polina |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 35-48 |
| Abstraksi Narasi | : | Soft Systems Methodology (SSM) telah lama digunakan di Eropa dan Amerika sebagai suatu cara untuk mengembangkan Sistem Informasi (SI). Meskipun demikian, hasil survei dalam penelitian ini menunjukkan bahwa SSM belum pernah digunakan sebagai suatu metodologi untuk mengembangkan SI di Indonesia. Metodologi yang telah digunakan di Indonesia selama ini berdasarkan pada Hard Systems Methodology (HSM). Penelitian ini memiliki dua tujuan terkait yaitu: Pertama, untuk mengetahui masalah apa yang dihadapi dalam pengembangan SI di Indonesia. Kedua, untuk mengetahui kemungkinan penggunaan SSM guna mengatasi masalah dalam pengembangan SI di Indonesia . Studi kasus dan penelitian tindakan dilaksanakan untuk menjawab tujuan penelitian ini. Hasil penelitian menunjukkan bahwa SSM dapat diterapkan di Indonesia. SSM dapat digunakan sebagai metodologi untuk mengatasi masalah-masalah dalam mengembangkan SI. SSM dapat membantu analisis maupun pengguna pada tahap evaluasi SI. SSM yang digabungkan dengan HSM dapat membantu analisis pada tahap identifikasi masalah, studi kelayakan, dan analisis kebutuhan. Hasil penelitian juga menunjukkan bahwa SSM lebih cocok untuk diterapkan pada organisasi/perusahaan yang menerapkan manajemen dengan pola demokrasi dibandingkan dengan organisasi/perusahaan yang menerapkan manajemen dengan pola otoriter. |
| Nama Pengarang | : | Pudjono, Joyce, Cen Jung |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 59-66 |
| Abstraksi Narasi | : | Since dibenzoyl recorsinol is a kind of ester compound, it was supposed that enzyme in microorganism consuming it would hydrolize dibenzoyl resorcinol, yielding one molecul of resorcinol and two molecul of benzoic acids. Both of these compounds have antimicrobe properties, and so it is expected that thay would increase the antiseptic activity of recorcinol. In this research dibenzoyl resorcinol was synthesized by reacting resorcinol and benzoyl chloride in pyridine as a solvent (modification of Schotten-Baumann method). The result analysis shows that synthetic product is a polish whitepowder, odorless, and tasteless. It does not contain hydroxy aromatic group such as resorcinol as a starting material, since it reacts negatively with FeCl3. It is insoluble in water but soluble in many organic solvents like eter, benzene, and chloroform. Melting point of synthetic product (117 derajad C) is higher than resorcinol (109 derajad C). Thin Layer Chromatography (TLC) test shows that the spot of synthetic product has Rf value of 0.93, which is different from the Rf value of resorcinol (0.53). Structure elucidation of the synthetic product by Infared (IR) and Nuclear Magnetic Resonance (NMR) spectroscopy shows spectra features, which are identified as the structure of dibenzoyl resorcinol. Mass Spectroscopy (MS) spectrum has molecul ionic peak which is in accordance with molecul weight of dibenzoyl resorcinol (318). Based on the above analysis, it is concluded that the synthetic product is indeed dibenzoyl resorcinol with a rendement of 51,54%. |
| Nama Pengarang | : | B. Djoko Untoro Suwarno |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 49-58 |
| Abstraksi Narasi | : | Convolution operation, which is a mathematical way of combining two signals to form a third one, is an important technique in Digital Signal Processing . Many students have difficulties in understanding the convolution operation. The main goal of this paper is to help the students in understanding the concept of convolution through visualitation using MATLAB R. |
| Nama Pengarang | : | A.A. Abdul-Razzak and S. M. Abdullah |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 9-18 |
| Abstraksi Narasi | : | In the present work, the finite element method has been used to investigate the behavior of reinforced concrete slabs in the pre- and post-cracking levels up to ultimate load. Nine-node Lagrangian degenerate elements, which are the general shear deformable elements, have been employed. An assumed transverse shear strain is used in the formulation to overcome the shear locking. A layered approach is adopted to discretize the concrete through the thickness. Both an elastic perfectly plastic and strain hardening plasticity approach, have been employed to model the compressive behavior of the concrete. The yield condition is formulated in terms of the first two stress invariants. The motion of the subsequen loading surfaces is controlled by the hardening rule, which is extrapolated from the uniaxial stress-strain relationship defined by a parabolic function. Concrete crushing is a strain-controlled phenomenon, which is monitored by a fracture surface similar to the yield surface. A smeared fixed crack approach is used to model the behavior of the cracked concrete, coupled with a tensile strength criterion to predict crack initiation. An attention is given also to the post-cracking shear strength. The steel is considered either as an elastic perfectly plastic material or as an elastic-plastic material with linear strain hardening. Steel reinforcement is assumed to have similar tensile and compressive stress-strain relationship. Several computer programs coded in FORTRAN language are written to implement the present study. These programs are arranged to give a complete listing of stresses and deformation in every concrete or steel layer. Several examples for which experimental results are published are analysized, using the proposed model and showed good agreement with the numerical results. |
| Nama Pengarang | : | J. Dharma Lesmono |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 91-95 |
| Abstraksi Narasi | : | Tulisan ini membahas penerapan solusi matriks-geometrik untuk menentukan unjuk kerja model antrian M/M/1 dalam lingkungan acak. Metode ini didasarkan pada struktur berulang takhingga dari matriks Q pada suatu Rantai Markov Kontinu dan kenyataan bahwa persamaan-persamaan linear yang digunakan untuk menentukan peluang stasioner memiliki solusi tunggal. Metode ini dapat juga diterapkan untuk model-model antrian yang lain. |
| Nama Pengarang | : | Mardi Santoso, Alfie Niamah Febriana, Joseph J. Brophy |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 75-79 |
| Abstraksi Narasi | : | Eucalyptus globulus labillardiere leaf oil has isolated in 0.18% w/w fresh wet basis yield by hydrodistillation for six hours using a Clevenger-type apparatus. The oil is light yellow, and its aroma similar to its leaves. Gas chromatography and gas chromatography-mass spectrometry analysis of the oil has identified twenty five components: four monoterpenes , a sesquiterpene, fourteen oxygenated monoterpenes, and six oxygenated sesquiterpenes. The major components of the oil were 1,8-cineole (11.49%), terpinyl acetate (6.84%), caryophyllene oxide (5.73%), ?-pinene (4.48%), and spathulenol (4.15%). |
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