| Nama Pengarang | : | Hendry Yanuar, Hardjono Sastrohamidjojo, Triyono, Jan C. T. Kwak |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 81-89 |
| Abstraksi Narasi | : | Telah dilakukan penelitian untuk memperoleh model kinetika oksidasi CO(g) oleh O2 dengan menggunakan katalis Cu2O/steelwool. Percobaan dilakukan di dalam suatu single tube fixed bed reactor, dengan ukuran panjang 15 cm dan diameter dalam 1,5 cm. Suhu percobaan berkisar antara 180 derajad - 300 derajad C, percobaan dibagi dalam dua kondisi: percobaan pertama oksidasi CO(g) sebagai fungsi konsentrasi CO(g) dengan konsentrasi O2(g) tetap (1,65 10^-5 mol/det) dan percobaan kedua oksidasi CO(g) sebagai fungsi konsentrasi O2(g) dengan konsentrasi CO(g) tetap (1,35 10^-5 mol/det). Serangkaian model kinetika oksidasi CO(g) disusun dengan didasarkan pada reaksi dasar pembentukan CO2(g), dengan tujuan untuk mendapatkan parameter-parameter kinetika reaksi. Hasil percobaan menunjukkan bahwa konversi dan laju reaksi oksidasi CO(g) meningkat seiring dengan meningkatnya konsentrasi reaktan dan suhu reaksi. Berdasarkan model kinetika yang diperoleh dapat disimpulkan bahwa reaksi oksidasi CO(g) oleh O2(g) dengan menggunakan katalis Cu2O/steelwool mengikuti mekanisme Langmuir-Hinshelwood. |
| Nama Pengarang | : | Luciana Kuswibawati |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 67-74 |
| Abstraksi Narasi | : | Most cases of malaria in travellers caused by protozoan parasite plasmodium could be prevented by improving pretravel advice to reduce contact with anopheline masquito and prophylactic use of antimalarial drugs. In this article we discuss life cycle of plasmodium, some new developments in malaria prophylaxis, including the assesment of malaria risk for travellers, problems in chemoprophylaxis and drug resistance, strategies for prevention of malaria, and currently available drugs for chemoprophylaxis. |
| Nama Pengarang | : | Bambang Sutopo |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 1-8 |
| Abstraksi Narasi | : | Digital signal processing with FFT (Fast Fourier Transform) enhances the computation time compared to the processing with DFT (Discrete Fourier Transform). In signal processing algorithms, multipliers contribute dominant effect on the computation time. Winograd algorithm is an effort to reduce the number of multipliers in FFT processors, using cyclic behavior in FFT algorithm. The advances in microelectronic technology, especially in FPGA (Field Programmable Gate Array), have made IC designing faster and easy to implement. Winograd algorithm is too sophisticated to implement in software, but has some advantages in hardware implementations. A ffour-point Winograd module for FFT has been developed in a XC4013 FPGA chip. The research shows that this module has 6 adder modules and one magnitude module, occupying 78% of the CLB in the chip. The computation time of this module is about 122 nanoseconds. |
| Nama Pengarang | : | S. Moertini, Veronica |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 19-34 |
| Abstraksi Narasi | : | As a tropical country, Indonesia has enormous amount of renewable energy resources. Currently, they have been converted to electrical and thermal energy, and utilized by many people. However, the converter units are generally at small scales and the resources taken are still very limited. While energy demand keeps on increasing, more efforts need to be done to explore the possibility of utilizing more renewable energy resources. A project of the Departemen Pertambangan dan Energy of RI has been executed with the goal of generating a renewable energy utilization master plan for East of Indonesia. This paper ptresents the result of the early stage of the project execution, which was done by studying many literatures. (The master plan generation will be discussed in another paper). It describes how to compute the potencies of six types of renewable energy by presenting the formulas and the data needed, and discusses the recent energy converter technologies and their relevancy as well. The excerpt of the technological coverage is as the following. Wind: wind power plant and the parameters affecting its performance. Biomass: bio conversion processes converting biomass to liquid and gaseous energy resources. Solar energy: photovoltaics and thermal converter technologies. Wave: four technologies converting wave energy to electrical energy. Tidal and geothermal energy: technological relevancy. The use of renewable energy resources in remote areas will also be presented. |
| Nama Pengarang | : | Sri Agustini Sulandari |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 91-98 |
| Abstraksi Narasi | : | Q-Switching is a mode of operating laser in which energy is stored in the laser material during pumping in the form of atoms in the upper laser level, and at a predictable time, released in a single, highenergy output, short ``giant pulse``. The technique of Q-switching is performed by introducing a shutter into the laser cavity. If the Shutter is closed, laser action cannot occur during pumping, and the population inversion can reach a value far beyond the threshold population that would have occurred if the shutter was not present. The stored energy and amplified gain both reach a high value. If the shutter is opened suddenly, the laser wil have a gain that greatly exceeds the losses, and the stored energy will be released in the form of a short and intense light pulse. Since this technique involves switching the cavity Q factor, from a low to a high value, it is known as Q-switching. This paper explores several techniques which have been used for Q-switching lasers. Each has its advantages, disadvantages and specific applications. |
| Nama Pengarang | : | oni Agustian dan Lilis Hermida |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 111-122 |
| Abstraksi Narasi | : | The anaerobic process of UASB operation is proved capable of treatment of various industrial liquid wastes to reduce concentration of the organic compounds. This operation type can accommodate high-concentration wastes with high organic loading rates. It is also better than other anaerobic operations. The UASB operation relies on development of conglomerates of highly immobilised and settleable granule sludge inside the reactor. Characteristics of liquid wastes, operating conditions of reactor, conditions of inoculum and micronutrient supply influence formation on dynamic equilibrium of microorganisms inside the reactor. However, start-up of the reactor and design factors of its construction are the key to successful operation. |
| Nama Pengarang | : | L.Wilardjo |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 99-102 |
| Abstraksi Narasi | : | Quantization of the energy of a particle trapped in a potential well was obtained by requiring that the ``wave picture`` of the particle forms a standing-wave pattern between the mutually-facing walls of the well.For high school students and freshmen in college, who are taking a course of Introductory Quantum Mechanics, this way of introducing quantization should be more readily understood, assuming that they have done experiments on such stationary waves or at least seen such a phenomenon demonstrated by their teacher. |
| Nama Pengarang | : | F.A. Rusdi Sambada |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 123-132 |
| Abstraksi Narasi | : | Thermal emissivity is defined as the ratio of the total energy emitted by a surface to the total energy emitted by a black surface at the same temperature, and is a function of the radiation wavelength, the incidence angle, the surface temperature, color, and its finishing touch. The goal of this research is to find out the effect color to its thermal emissivity. The color of a glass is defined by its absorptivity. Glass with higher absorptivity has darker color. This research is carried out by using three variations of glass absorptivity and the necessary data to calculate the thermalemissivity of the glass are collected for each variation. The result is that thermal emissivity of a glass will be increasing as its absorptivity increases. |
| Nama Pengarang | : | Alb. Setiyoko |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 103-109 |
| Abstraksi Narasi | : | A theoritical estimation of cellular telephone radiation effect on human brain has been done. This is achieved by calculating electromagnetic wave energy absorbed by water molecules in the brain. The result shows that there is an increase in brain temperature about 5 C due to continuing use of cellular telephone up to 1 hour. |
| Nama Pengarang | : | Rita Suhadi |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 151-158 |
| Abstraksi Narasi | : | Medical practitioners are busy professionals with limited time to upgrade their knowledge. Meanwhile,the medicine used in their medical practice was intensively advertised through various media including printing materials. Medical advertisements have both commercial and scientific aspects. Commercially it tends to exaggerate the product benefit,whereas scientifically it should be exact, truthful, and reliable. If doctors fully trust and depend on the advertisements as the only source of information, they may yield irrational therapy. This descriptive non-experimental study was conducted using 120 samples of printing advertisements for doctors to investigate the rationality of the advertisements, the comparison between the ``PMA`` (foreign companies) and ``PMDN/BUMN`` (local companies) medical advertisements, and the comparison between several therapeutic classes and media of advertisements. The 1988 WHO ethical criteria were applied as standard. The study shows that the percentage of rational advertisements is only 5% for PMDN/BUMN, and 17 % for PMA advertisements. It Is also depicted by the percentage figures that the rationality is influenced by the types of media and the product`s therapeutic class. |
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