Articles

Stimulating Green Growth in Bandung’s Food Sector: An Agent Based Simulation on Food Waste Problem

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Food waste is one of the primary contributors to environmental change in Indonesia, posing a significant threat to global sustainability. Food waste in landfills contributes to more methane emissions than any other landfilled material due to its quick decay rate. One of these problems is occurring in the Bandung area, where a humanitarian tragedy caused by a garbage explosion and landslide took place 20 years, leading to a severe waste problem. A similar issue is now happening again. The latest data shows that the final waste disposal site in Bandung area has reached 1200% of its capacity, with around 45% of total waste being dominated by food waste. As a response to this situation, this study simulated the food waste problem in Bandung area, especially in a buffet restaurant to identify the mechanisms beyond the waste problem and find a solution. This study proposes an Agent-Based Modelling as a tool to explain the food waste problem in Bandung, Indonesia and how to reduce it, as shaped by different scenarios. Our simulations indicate that introducing the new policy can reduce the amount of food waste generated by the restaurant. The most effective one is the mixed instrument of rewards and fines policy.

Numerical Simulation in Gas Hydrate Formation

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The formation of gas hydrates is an undesirable process in the natural gas transportation industry, ensuring the blockage of pipelines and especially the reduction of transport flows and the increase of working pressure. That is why it is necessary to simulate the water adsorption processes using chemicals as well as the mathematical simulation of the processes. The article presents data on the simulation stages and especially the behavior of natural gas with water content in main pipelines.

Effect of Aquifer Strength and Gas-cap Size on Oil Recovery Efficiency in Thin-Oil Rim

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Recovering oil from thin oil rim reservoirs depends on some factors such as the gas-cap size, thickness of initial oil column, aquifer strength, permeability anisotropy (kV/kH), and rock and fluid properties. The arbitrary selection of these factors by researchers during investigation limits the systematic assessment of the influence of these factors on hydrocarbon recovery from thin oil rim reservoirs. This work investigated the effect of aquifer strength, gas cap size, and permeability anisotropy on hydrocarbon recovery, using design of experiment (DOE) as a tool in the systematic selection of some of the factors that influence hydrocarbon recovery. A static model of the base case oil rim was built in Petrel. Using Eclipse simulator, two other reservoir models having different gas cap sizes from the base case were built. Forty-eight simulation cases were generated using the result from the design of experiment (DOE). The aquifer model used is a Fetkovich analytical aquifer model, and the aquifer volume factors used for this investigation are 0.7, 1.0, 1.5 and 2.5, while the gas cap sizes (m-factor) used are 0.5, 1.0 and 2.0.  The permeability anisotropy used are 0.01, 0.05, 0.10 and 0.40. Each simulation case was made to run for a period of twenty years (20years) and the results for the Field Oil Efficiency (FOE), Field Water Production Total (FWPT) and Field Gas Production Total (FGPT) were obtained and analyzed. It was found from this study that, the oil percentage recovery will increase as the gas cap size is decreased, while the percentage gas and water recoveries will increase as the size of the gas cap is increased for a thin oil rim reservoir. Again, for a thin oil rim reservoir with gas cap size of 0.50 ≤ m ≤ 2.00, percentage recovery of gas, oil and water will increase with aquifer volume. Also, based on the result obtained, a thin oil rim reservoir with small to moderate gas cap size (0.5≤ m≤1.0) will yield higher oil recoveries irrespective of the kV /kH ratio.

Modelling Cyclic Fluctuations of SEIR Epidemic Diseases

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Seasonality of infectious disease is an important factor in disease incidence, outbreaks, control and prevention. Many mathematical models that incorporate seasonality in the transmission were formulated and analyzed. In this essay a qualitative analysis is given in terms of the effective reproduction number R0, the existence and stability of the disease-free equilibrium and endemic equilibrium of both the SEIR model and seasonal SEIR model. We perform numerical simulations  to validate the model formulation.