GM Korea

About: GM Korea is a based out in . It is known for research contribution in the topics: Diesel engine & Diesel exhaust. The organization has 16 authors who have published 11 publications receiving 136 citations.

Resource Welfare Based Task Allocation for UAV Team with Resource Constraints

Abstract: This paper addresses a task allocation problem for a team of UAVs that cooperatively performs a search and attack mission in an unknown region. The UAVs are heterogeneous carrying different types and amounts of munition resources, and limited in communications and sensing capabilities. The environment is highly uncertain and dynamic where no prior information is available and dynamic events such as UAV failures unpredictably occur. The objective of the mission is to maximize total reward obtained by destroying targets within a given mission horizon. A group of UAVs may need to be formed to attack a target because individual UAVs may not have sufficient resources for the execution of attack tasks. Instantaneous task allocation approaches that seek for optimal solution for current tasks cannot effectively account for the unpredictability of future tasks in the uncertain dynamic environment. In this paper, we propose a distributed task allocation scheme based on resource welfare of which concept is adopted from economics. The approach we present enables the UAV team to effectively utilize resources by balancing resource depletions and consequently be capable of smoothly responding to dynamic events by retaining more UAVs available. Simulation experiments were conducted in various conditions to evaluate the performance of the proposed approach in comparison with the instantaneous task allocation method. The results show that our approach improves the performance by up to 29.3 % with respect to the instantaneous task allocation method.

Effects of split injection, oxygen enriched air and heavy EGR on soot emissions in a diesel engine

Abstract: The effects of split injection, oxygen enriched air, and heavy exhaust gas recirculation (EGR) on soot emissions in a direct injection diesel engine were studied using the KIVA-3V code. When split injection is applied, the second injection of fuel into a cylinder results in two separate stoichiometric zones, which helps soot oxidation. As a result, soot emissions are decreased. When oxygen enriched air is applied together with split injection, a higher concentration of oxygen causes higher temperatures in the cylinder. The increase in temperature promotes the growth reaction of acetylene with soot. However, it does not improve acetylene formation during the second injection of fuel. As more acetylene is consumed in the growth reaction with soot, the concentration of acetylene in the cylinder is decreased, which leads to a decrease in soot formation and thus soot emissions. A combination of split injection, a high concentration of oxygen, and a high EGR ratio shows the best results in terms of diesel emissions. In this paper, the split injection scheme of 75.8.25, in which 75% of total fuel is injected in the first pulse, followed by 8°CA of dwell time, and 25% of fuel is injected in the second pulse, with an oxygen concentration of 23% in volume and an EGR ratio of 30% shows a 45% reduction in soot emissions, with the same NOx emissions as in single injection.

Effect of the Reynolds number on the conjugate heat transfer around a circular cylinder with heat source

Abstract: Conjugate heat transfer around a circular cylinder with heat source was numerically investigated Both the forced convection of water and conduction of carbon-steel were involved in the present simulation A finite element formulation based on SIMPLE type algorithm was adopted for solving the incompressible Navier-Stokes equations coupled with energy equation A conduction heat transfer problem inside the cylinder was trivially coupled with forced convection around the cylinder by using the Galerkin formulation of energy equation The proposed algorithm was verified by solving the benchmark problem of conjugate heat transfer inside a cavity having a centered body The effect of the Reynolds number on the temperature distribution on the cylinder surface and the maximum temperature inside the cylinder was examined It was shown that the maximum temperature decreased as Reynolds number increased and that the position of the maximum temperature moved from the center to the rear part of the cylinder till Re = 20 and then moved back toward the center beyond Re = 20 since the reverse flow around the rear part of the cylinder became stronger as the Reynolds number further increased Lastly, the maximum temperature of the cylinder with rotation was higher than that of the fixed one and the position of the maximum temperature inside the cylinder depended on the position and the strength of the dead zone