| Nama Pengarang | : | A. A. Abdul-Razzak and S. M. Abdullah |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 123-133 |
| Abstraksi Narasi | : | This paper describes the application of finite element method to investigate the behaviour of reinforced concrete shells in the pre-and post-cracking levels up to the ultimate load. Nine-node Lagrangian degenerate elements, which are the general shear deformable elements, have been employed. An assumed shear and membrane strain in the orthogonal curvilinear coordinate system is used in the formulation to avoid shear and membrane-locking behaviour. 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 behaviour of the concrete. The yield condition is formulated in terms of the first two stress invariants. The motion of the subsequent loading surfaces is controlled by the hardening rule, which is extrapolated from the uniaxial stress-strain relationship given 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 behaviour of the cracked concrete, coupled with a tensile strength criterion to predict crack initiation. Tension stiffening effect in the cracked concrete has been taken into account. 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 response to tensile or compressive force. Both an elastic perfectly plastic and strain hardening plasticity approach have been employed to model the compressive behaviour of the concrete. The motion of the subsequent loading surfaces is controlled by the hardening rule, which is extrapolated from the uniaxial stress-strain relationship given by a parabolic function. Concrete crus |
| Nama Pengarang | : | Veronica S. Moertini |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 105-122 |
| Abstraksi Narasi | : | Due to mainly geographical condition, numerous remote areas in East Indonesia are still lacking of electricity. The power grid owned by PT PLN is not extended to these areas yet because of economical reasons. The price of conventional energy resources to provide thermal energy is still high as well, as a result of the difficulties in transportation. It is a prudent move of the Indonesian Government to have been trying to find ways to resolve these problems by seeking the substitutes to provide sufficient and cheap energy for the local community. Renewable energy resources in East Indonesia are plentiful, but have not been very much utilized yet. A project has been executed to collect the related data, compute the potencies of each type of the renewable energy resources, analyze the technological and economical aspects, and eventually generate a renewable energy utilization master plan. This paper presents the result of the work execution, by focusing primarily on the method of how the master plan has been drawn. |
| Nama Pengarang | : | Fenty |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 159-165 |
| Abstraksi Narasi | : | People in Indonesia tend to use traditional medicines to cure their illnesses. One of the traditional medicines frequently used is herbal medicine (jamu) for pain relieve. The purpose of this research is to prove by using chemical stimulating method that herbal medicine for pain relieve has analgesic potency in female mice and to investigate the percentage of the potency. The reseacrh is purely experimental using one-way completely random design. The writhing method with acetic acid as stimulant was used to determine the analgesic potency. The percentage of the analgesic potency was calculated using the Hendersoth-Forsaith formula. The data were analyzed using one-way anava and Tukey HSD test at 95% level of confidence. The results of the research indicated that the average percentage of analgesic potency (Mean ±SE) for the positive control was (57,84±2,61)%, and for the3^rd, 4^th, and 5^th group of herbal medicine for pain relieve were (-9,24±6,71)%, (37,94±1,71)%, and (72,42±2,33)% respectively. The herbal medicine for pain relieve with 10192 mg/kg BW dose-level did not show significant differences compared to positive control. The herbal medicine for pain relieve with 5096 mg/kg BW dose-level showed analgesic potency, but was lower than the positive control. From the results, it can be concluded that the higher the dose-level of the herbal medicine for pain relieve, the higher its analgesic potency. |
| Nama Pengarang | : | Damanik, Asan, Fenty, S. Moertini, Veronica, Abdul-Razzak, A.A., S.M. Abdullah, Anastasia Rita Widiarti, Sahat Simbolon, Hanoch J. Sohilait, C.M. Ratna Rini Nastiti, Kadarwati Budihardjo, Sri Gunawan |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 175-181 |
| Abstraksi Narasi | : | Using the more general vertex factor ... for lepton-neutrino interactions in the scheme of intermediate vector boson theory, one can obtain Feynman amplitude M and transition probability density ... in the general forms. The vertex factor ... , as one can find in electro-weak interactions theory, is only a special case of the general vertex factor proposed in this paper, i.e. for a= -1. We also propose the use of the general vertex factor in calculating the decay rate and the differential cross-section in determining the value of parameter a by fitting the experimental data. |
| Nama Pengarang | : | H. Harsoyono, Antonio Sergio B. Sombra |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 81-92 |
| Abstraksi Narasi | : | The coupled mode equation incorporating the intensity dependent refractive index (IDRI), which is a nonlinear optical effect of the medium, was applied to basic study of beam propagation in a symmetrically configured five-layer planar structure composed of two optically coupled waveguides with identical optically nonlinear guiding media. The two cladding layers and the substrate layer are composed of linear optical materials of different refractive index. The results of the simulation indicate that the capability of the symmetrical waveguide with coupling length Lc to function perfectly as optical switching depends on the linear coupling coefficient, input power, guide separations, and width of the waveguides. |
| Nama Pengarang | : | Henry P. Panggabean |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 29-41 |
| Abstraksi Narasi | : | One-machine scheduling problem is one of non-deterministic NP-complete problems. Carlier algorithm is one of the best heuristic method to solve this problem. This paper presents the implementation of simulated annealing (SA) algoritm to solve one-machine scheduling problem, and the comparison of its performance to Carlier algorithm in terms of quality of the solution (measured by makespan) and computation time. It is concluded that SA algorithm outperforms Carlier algorithm in the quality of solution in most cases tested, although in relatively greater computation time. Moreover, due to its probabilistic, SA algorithm can produce more than one possibility of solution with same makespan. |
| Nama Pengarang | : | Ridowati Gunawan |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 43-50 |
| Abstraksi Narasi | : | Web server log is a computer document produced by a web server. This document records all activities of the server`s visitors. The data produced by a server log depend on the frequency of access to the web site. The higher the number of ``hits`` to the web, the bigger the data produced by the web server log. Unfortunately, most of web server administrators still do not know how to utilize a web server log to produce better informations. A much needed information, for example, is the navigation pattern of a web site, which includes the pages frequently accessed by certain users and the effectivity of the web site. One of the techniques used to process such information is the association rule using apriori algorithm. |
| Nama Pengarang | : | Mardi Santoso |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 11-15 |
| Abstraksi Narasi | : | Reactions of 2-amino-4,5-dimethoxyacetophenone (3) with phenacylbromides in N,N-dimethylforamide were investigated in attempt to synthesise new 2-acylindoles (6, 8b). The reaction clearly gave new 2-aryl-5,6-dimethoxy-3-methylindoles (7,9). Their structures were determined using NMR and mass spectroscopy. The reactions could be suggested as a one-pot-access to synthesise various 2-aryl-5,6-dimethoxy-3-arylindoles. |
| Nama Pengarang | : | James J. Spillane, SJ |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 93-101 |
| Abstraksi Narasi | : | Many businesses have now become integrated and heavily dependent on computer technology. This paper discusses the importance, complexity, and urgency of digital security in the information age. Information technology has a hugely important effect because it is allowing knowledge to spread nearly instantly and making it accesible to everyone. It is dangerous to entrust your company, your organization, your personal information, or indeed your life to a systems to a system that is full of security holes. Improving information systems means implementing appropriate policies, removing preverse incentives and managing risks, not just buying clever hardware and software. Digital security depends as much - if not more - on human cultural factors as it does on technology. The amount of time and money to be spent of digital security is a matter of an appropriate balance between cost and risk - and what is appropriate for the organization. |
| Nama Pengarang | : | Joni Agustian |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 73-80 |
| Abstraksi Narasi | : | Capabilities of genetically modified organisms are currently still debated, but their applications in industrial production and their distribution to consumers have been implemented since 1996. Based on these facts, discussion on a system capable of protecting consumers` rights is important. In this article, a reliable system capable of tracing the presence of genetically modified organisms and their derivative products is discussed. Two strategies which can be applied in such system are the labelling and the analytical methods. The using of labels is an effective way to give informations to consumers, but it depends on the results of global policies on these organisms. The analytical method is used to isolate the organisms. The polymerase Chain Reaction (PCR) is presently the most effective and efficient analytical method, and is developing rapidly in developed countries. Combination of both methods could form a reliable system in tracing the presence of genetically modified organisms, but standards protocols must be used to prevent polemics. |
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