Articles
<![CDATA[Analisis Hubungan Frekuensi-Magnitudo Gempa Bumi di Bali dan Sekitarnya ]]>
<![CDATA[Wandono Wandono]]>;
<![CDATA[Sri Widiyantoro]]>;
<![CDATA[Gunawan Ibrahim]]>;
<![CDATA[Edy Soewono]]>
<![CDATA[ Jurnal Matematika & Sains Vol 9, No 3 (2004) ]]>
Publisher : <![CDATA[Institut Teknologi Bandung ]]>
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<![CDATA[We mapped the 3-D b-value variation in Bali and its vicinity through analyzing the frequency-magnitude relation. A high b-value anomaly is observed beneath the Lombok volcanic arc at 90-180 km depth interval. It is related to the zone of partial melting of basaltic magma on the subducted slab of Indian oceanic plate beneath the Eurasian plate in Nusa Tenggara Barat. This analysis supports the hypothesis about the existence of melting point on the slab.]]>
<![CDATA[Optimization of Vertical Well Placement for Oil Field Development Based on Basic Reservoir Rock Properties using a Genetic Algorithm ]]>
<![CDATA[Ariadji, Tutuka]]>;
<![CDATA[Sukarno, Pudjo]]>;
<![CDATA[Sidarto, Kuntjoro Adji]]>;
<![CDATA[Soewono, Edy]]>;
<![CDATA[Riza, Lala Septem]]>;
<![CDATA[David, Kenny]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 44, No 2 (2012) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/itbj.eng.sci.2012.44.2.2
<![CDATA[Comparing the quality of basic reservoir rock properties is a common practice to locate new infill or development wells for optimizing oil field development using reservoir simulation. The conventional technique employs a manual trial-and-error process to find new well locations, which proves to be time-consuming, especially for large fields. Concerning this practical matter, an alternative in the form of a robust technique is introduced in order to reduce time and effort in finding new well locations capable of producing the highest oil recovery. The objective of this research was to apply a genetic algorithm (GA) for determining well locations using reservoir simulation, in order to avoid the conventional manual trial-and-error method. This GA involved the basic rock properties, i.e. porosity, permeability, and oil  saturation, of each grid block obtained from a reservoir simulation model, to which a newly generated fitness function was applied, formulated by translating common engineering practice in reservoir simulation into a mathematical equation and then into a computer program. The maximum fitness value indicates the best grid location for a new well. In order to validate the proposed GA method and evaluate the performance of the program, two fields with different production profile characteristics were used, fields X and Y. The proposed method proved to be a robust and accurate method to find the best new well locations for oil field development. The key to the success of the proposed GA method lies in the formulation of the objective functions.]]>
<![CDATA[Cost Minimization Model of Gas Transmission Line for Indonesian SIJ Pipeline Network ]]>
<![CDATA[Siregar, Septoratno]]>;
<![CDATA[Soewono, Edy]]>;
<![CDATA[Siregar, Daniel]]>;
<![CDATA[Putra, Satya A.]]>;
<![CDATA[Budicakrayana, Yana]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 35, No 1 (2003) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/itbj.eng.sci.2003.35.1.3
<![CDATA[Optimization of Indonesian SIJ gas pipeline network is being discussed here. Optimum pipe diameters together with the corresponding pressure distribution are obtained from minimization of total cost function consisting of investment and operating costs and subjects to some physical (Panhandle A and Panhandle B equations) constraints. Iteration technique based on Generalized Steepest-Descent and fourth order Runge-Kutta method are used here. The resulting diameters from this continuous optimization are then rounded to the closest available discrete sizes. We have also calculated toll fee along each segment and safety factor of the network by determining the pipe wall thickness, using ANSI B31.8 standard. Sensitivity analysis of toll fee for variation of flow rates is shown here. The result will gives the diameter and compressor size and compressor location that feasible to use for the SIJ pipeline project. The Result also indicates that the east route cost relatively less expensive than the west cost.]]>
<![CDATA[A Particle System Model for Dengue Transmission ]]>
<![CDATA[Zevika, Mona]]>;
<![CDATA[Soewono, Edy]]>;
<![CDATA[Tse, Oliver T.C.]]>
<![CDATA[ Communication in Biomathematical Sciences Vol 1, No 1 (2017) ]]>
Publisher : <![CDATA[Indonesian Bio-Mathematical Society ]]>
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DOI: 10.5614/cbms.2017.1.1.3
<![CDATA[Dengue disease has been known for decades as a vector-borne disease which is rapidly spreading in many tropical and subtropical countries. The disease is transmitted mostly by female Aedes aegypty mosquitoes. Although detailed biological properties of the infection process are already known, in the field applications the disease transmission of dengue is still far from being successfully controlled. The complexity surrounding the transmission is contributed by various factors such as climate, mobility and human-mosquito behavior. Many deterministic models have been developed to investigate the spread of dengue. However, in a deterministic model, spatial heterogeneity factor is not considered. In fact, distances between people and mosquitoes greatly influence the spread of dengue. This paper discusses a microscopic model of the spread of dengue based on spatial heterogeneity. In this microscopic model, every human and mosquito is regarded as a particle and the corresponding human and mosquito populations with their health status are considered as a system of particles. Three important dynamical factors and processes are constructed for each particle, i.e., position and health status of each particle, natural birth and death, infection and transition processes. An estimate of the corresponding basic reproductive ratio is introduced to accommodate the variation of health status and spatial spread of particles]]>
<![CDATA[A Dynamical Model of ’Invisible Wall’ in Mosquito Control ]]>
<![CDATA[Khumaeroh, Mia Siti]]>;
<![CDATA[Soewono, Edy]]>;
<![CDATA[Nuraini, Nuning]]>
<![CDATA[ Communication in Biomathematical Sciences Vol 1, No 2 (2018) ]]>
Publisher : <![CDATA[Indonesian Bio-Mathematical Society ]]>
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DOI: 10.5614/cbms.2018.1.2.2
<![CDATA[A concept of an ?invisible wall? is used here as a control mechanism to separate the human population from mosquitoes in the hope that mosquitoes gradually change their preference to other blood resources. Although mosquitoes carry inherent traits in host preference, in a situation in which regular blood resource is less available, and there are abundant other blood resources, mosquitoes may adapt to the existing new blood resource. Here we construct a model of mosquitoes preference alteration involving anthropophilic, opportunistic, and zoophilic, based on the application of repellent clothing usage and the effects of fumigation. The coexistence equilibrium is shown to be stable when the rate of mosquito ovulation, which is successfully hatching into larvae, is greater than the total of mosquito natural death rate and mosquito death rate due to fumigation. Numerical simulation is performed after the reduction of unobservable parameters is done with Human Blood Index (HBI) data. Global sensitivity analysis is then performed to determine the parameters that provide the dominant alteration effect on the mosquito population. The simulation results show that a proper selection of the fumigation rate and repellent clothing rate should be carefully done in order to reduce the mosquito population as well as to increase the zoophilic ratio.]]>
<![CDATA[ON THE ANALYSIS OF COVID-19 TRANSMISSION IN WUHAN, DIAMOND PRINCESS AND JAKARTA-CLUSTER ]]>
<![CDATA[Soewono, Edy]]>
<![CDATA[ Communication in Biomathematical Sciences Vol 3, No 1 (2020) ]]>
Publisher : <![CDATA[Indonesian Bio-Mathematical Society ]]>
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DOI: 10.5614/cbms.2020.3.1.2
<![CDATA[The whole world has been recently shocked by the massive spread of Covid-19 without any sign of when it will end. This phenomenon of this scale is understood as a plague that has never been happening in a lifetime. Almost all countries do not have proper preparedness when positive cases are found in a region. In a relatively short time, cases then spread quickly, and panic broke out in the community. With the rapid human to human transmission, and there is no vaccine available, the only way to control the spread of the disease is by implementing a contact tracing and isolation policy. The fact indicated that health officials in many affecting countries have difficulty in detecting individuals who are potentially exposed to the virus. The success of controlling the disease is very much dependent on the ability of the health authority in tracking and isolating the infected and the suspected cases. A transmission model for Covid-19 transmission in the form of SEIR is chosen to fit with the cases in Wuhan, Diamond Princess, and Jakarta-cluster. These cases represent the transmission in a large city, a relatively restricted and dense area, and a small cluster, respectively. The basic reproductive ratio and the infection rate are obtained based on the cumulative data for each case. These indicators can be used for predicting the progress of transmission for similar cases. A simple model for estimating the completing time of contact tracing and isolation is constructed in the form of a differential operator on the cumulative case. This operator represents the number of daily new infected cases. It is shown that for the case of Wuhan, the completing time for contact tracing and isolation is 55 days. This result is important for analyzing the intervention strategy of Covid-19 in an affected region.]]>
<![CDATA[A Mathematical Model of Intermittent Gas Lift in Elevation-Production Operation with Line-Pack and Line-Drafting Phenomena in a Gas Line ]]>
<![CDATA[Silvya Dewi Rahmawati]]>;
<![CDATA[Tasmi Tasmi]]>;
<![CDATA[Pudjo Sukarno]]>;
<![CDATA[Agus Yodi Gunawan]]>;
<![CDATA[Edy Soewono]]>;
<![CDATA[Septoratno Siregar]]>;
<![CDATA[Edward L. Tobing]]>
<![CDATA[ Journal of Earth Energy Engineering Vol. 9 No. 2 (2020): OCTOBER ]]>
Publisher : <![CDATA[Universitas Islam Riau (UIR) Press ]]>
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DOI: 10.25299/jeee.2020.5264
<![CDATA[This paper discusses a transient model of the intermittent gas lift technique in an oil well. The model is developed in the gas line, in the tubing-casing annulus, and the tubing. The line-pack and line-drafting phenomena in the gas line are considered in the model. A numerical approach will be used to solve the mathematical model that represents fluid flow during intermittent gas lift injection. The dynamics of important variables in the intermittent gas lift are investigated and analyzed to determine the best production strategy for intermittent gas lift. The variables are film thickness and velocity, slug height and velocity, and gas height and velocity. The relationships between surface injection control parameters (gas injection pressure and gas injection rate) and the velocity and height of film, gas, and liquid are shown in one cycle of the gas lift intermittent process. The higher the gas injection pressure, the faster the gas injection velocity, and the thinner the film thickness in the tubing. In order to obtain clean tubing from film thickness, the gas injection pressure needs to be optimized, which will lead to maintaining compressor discharge pressure availability. Detailed observation of the dynamic performance inside the tubing production well will give the optimum oil production rate for oil wells under a gas lift intermittent production strategy for field application.]]>
<![CDATA[MODEL MATEMATIKA PENYEBARAN PENYAKIT DEMAM BERDARAH ]]>
<![CDATA[Asep K. Supriatna]]>;
<![CDATA[Edy Soewono]]>
<![CDATA[ Bionatura Vol 2, No 3 (2000): Bionatura Desember 2000 ]]>
Publisher : <![CDATA[Direktorat Sumber Daya Akademik dan Perpustakaan ]]>
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<![CDATA[Di dalam paper ini dibahas model matematika deterministik untuk penyebaranpenyakit demam berdarah. Ambang batas epidemik dapat ditentukan sebagaifungsi dari pertumbuhan nyamuk Aedes aegypti. Pertumbuhan nyamuk ini jugamenentukan kestabilan dari state bebas demam berdarah dan state endemikdemam berdarah. Analisis selanjutnya memperlihatkan bahwa pengontrolanepidemik yang efektif adalah dengan cara mengontrol pertumbuhan nyamuktersebut secara periodik.Kata kunci : model matematika, demam berdarah, ambang batas epidemik, state bebas demamberdarah, state endemik demam berdarah, kestabilan titik tetap, Aedes aegypty]]>
<![CDATA[Optimization of Vertical Well Placement for Oil Field Development Based on Basic Reservoir Rock Properties using a Genetic Algorithm ]]>
<![CDATA[Tutuka Ariadji]]>;
<![CDATA[Pudjo Sukarno]]>;
<![CDATA[Kuntjoro Adji Sidarto]]>;
<![CDATA[Edy Soewono]]>;
<![CDATA[Lala Septem Riza]]>;
<![CDATA[Kenny David]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol. 44 No. 2 (2012) ]]>
Publisher : <![CDATA[Institute for Research and Community Services, Institut Teknologi Bandung ]]>
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DOI: 10.5614/itbj.eng.sci.2012.44.2.2
<![CDATA[Comparing the quality of basic reservoir rock properties is a common practice to locate new infill or development wells for optimizing oil field development using reservoir simulation. The conventional technique employs a manual trial-and-error process to find new well locations, which proves to be time-consuming, especially for large fields. Concerning this practical matter, an alternative in the form of a robust technique is introduced in order to reduce time and effort in finding new well locations capable of producing the highest oil recovery. The objective of this research was to apply a genetic algorithm (GA) for determining well locations using reservoir simulation, in order to avoid the conventional manual trial-and-error method. This GA involved the basic rock properties, i.e. porosity, permeability, and oil saturation, of each grid block obtained from a reservoir simulation model, to which a newly generated fitness function was applied, formulated by translating common engineering practice in reservoir simulation into a mathematical equation and then into a computer program. The maximum fitness value indicates the best grid location for a new well. In order to validate the proposed GA method and evaluate the performance of the program, two fields with different production profile characteristics were used, fields X and Y. The proposed method proved to be a robust and accurate method to find the best new well locations for oil field development. The key to the success of the proposed GA method lies in the formulation of the objective functions.]]>
<![CDATA[Cost Minimization Model of Gas Transmission Line for Indonesian SIJ Pipeline Network ]]>
<![CDATA[Septoratno Siregar]]>;
<![CDATA[Edy Soewono]]>;
<![CDATA[Daniel Siregar]]>;
<![CDATA[Satya A. Putra]]>;
<![CDATA[Yana Budicakrayana]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol. 35 No. 1 (2003) ]]>
Publisher : <![CDATA[Institute for Research and Community Services, Institut Teknologi Bandung ]]>
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DOI: 10.5614/itbj.eng.sci.2003.35.1.3
<![CDATA[Optimization of Indonesian SIJ gas pipeline network is being discussed here. Optimum pipe diameters together with the corresponding pressure distribution are obtained from minimization of total cost function consisting of investment and operating costs and subjects to some physical (Panhandle A and Panhandle B equations) constraints. Iteration technique based on Generalized Steepest-Descent and fourth order Runge-Kutta method are used here. The resulting diameters from this continuous optimization are then rounded to the closest available discrete sizes. We have also calculated toll fee along each segment and safety factor of the network by determining the pipe wall thickness, using ANSI B31.8 standard. Sensitivity analysis of toll fee for variation of flow rates is shown here. The result will gives the diameter and compressor size and compressor location that feasible to use for the SIJ pipeline project. The Result also indicates that the east route cost relatively less expensive than the west cost.]]>
