Study of n-C<Subscript>12</Subscript>H<Subscript>26</Subscript> reforming over DFC catalyst in a simulated diesel exhaust

In lean-DeNOX catalysis reactions, hydrogen is a good reducing agent in PGM catalysts as well as an effective promoter in selective catalytic reduction reactions over base metal oxide catalysts. However, such a lean-DeNOX system, which uses hydrogen, requires an on-board fuel reforming system applicable to internal combustion engines. In this study, catalytic partial oxidation (CPOx) performance was tested in a laboratory for various reactants and hydrocarbon conditions. Volume concentrations of 5–10% oxygen and 0-5% water vapor were used to simulate diesel exhaust, and n-C₁₂H₂₆ was used as the feedstock for the reforming reaction. In the CPOx of n-C₁₂H₂₆, the highest hydrogen selectivity was 64% and was achieved at 100,000 h-1 GHSV. Additionally, the C/O ratio was less than unity in the absence of water vapor. However, as the water concentration was increased to 2.5 and 5.0 vol. % in the n-C₁₂H₂₆ CPOx reactions, the maximum hydrogen selectivity was increased from 64% in the absence of water to 70% and 75%, respectively. This effect is a consequence of the water-gas shift reaction over the catalyst bed. Regarding oxygen concentration effects, hydrogen selectivity slightly increased with increasing oxygen concentration from 10% to 15%. It was also found that the CPOx reaction of n-C₁₂H₂₆ can be ignited at temperatures below 300 C. Accordingly, it can be concluded that CPOx is a useful and feasible device for promoting diesel DeNOx catalysis in terms of hydrogen productivity and reaction initiation.     

Establishment of an installation process of a valve seat to a cylinder head using the cae technique

Valve seats press-fitted in the cylinder head function to hold exhaust gas inside the ignition chamber and to transfer heat to the coolant moving in the water jacket of the head. The press-fitting of the valve seats to the head at ambient temperature has been widely spread out due to its many advantages over pressing with frozen valve seats or with a heated head. The benefits include lower equipment costs, lower running costs, and fewer installation faults during the press-fitting. Nevertheless, a systematic approach for pressing at ambient temperature (ATP; ambient temperature press-fitting) has not been studied and analyzed to date. A technique to check the reliability of the press-fitting by measuring hoop strain inside the valve seat and the FEM procedure to simulate ATP is developed in this study. The FEM procedure of ATP developed here exhibits a concurrence with experimental results. Utilizing the DOE (Design of Experiments) technique, we determined the effects of various geometric parameters and the optimal shapes of the valve seat and cylinder head. The optimal shapes have been successfully applied in an actual engine and varified in a running-engine test.     

Simplified dynamics model for axial force in tripod constant velocity joint

Tripod constant velocity (TCV) joints are common components in automotive and mechanical applications. The benefits of the TCV joint are its high plunge capacity and high torque capacity. During power transmission, the friction inside the joint generates an axial force according to the kinematics. This force causes noise and vibration problems. In this study, a simplified multi-body dynamic model based on a phenomenological TCV joint friction model is developed. This model considers the generated axial force (GAF) of a TCV joint with different lubricate conditions. The efficiency and accuracy are verified by comparison with other prediction models and experiments. Thus, this model can be used to design and control the manufacture process of TCV joints.     

Analytical study of pressure pulsation characteristics according to the geometries of the fuel rail of an MPI engine

In a conventional MPI engine, a pulsation damper is usually mounted on the fuel rail to diminish undesirable noise in the vehicle cabin room; however, pulsation dampers are quite expensive. Therefore, several studies have focused on reducing fuel pressure pulsation by increasing the self-damping characteristics of the fuel rail. This paper details the development of a fuel rail that reduces pulsation using a self-damping effect. Using an oil hammer simulation technique, pressure pulsation characteristics were investigated with respect to the aspect ratio of the cross-section, wall thickness, and fuel rail material. Increasing the aspect ratio and decreasing the wall thickness efficiently reduced the pressure pulsation. In addition, the pressure pulsation characteristics were investigated with respect to the resonant engine speed and injection period. These simulated data can be used to reduce the pressure pulsation peak and to avoid the resonant point in the design stage during the development of a fuel rail.     

Development of an electric active rollcontrol (ARC) algorithm for a SUV

Cornering maneuvers with reduced body roll and without loss in comfort are leading requirements for car manufacturers. An electric active roll control (ARC) system controls body roll angle with motor-driven actuators installed in the centers of the front and rear stabilizer bars. A vehicle analysis model developed using a CarSim S/W was validated using vehicle test data. Two ARC algorithms for a sports utility vehicle (SUV) were designed using a sliding-mode control algorithm based on a nonlinear roll model and an estimated lateral acceleration based on a linearized roll model. Co-simulation with the Matlab simulink controller model and the CarSim vehicle model were conducted to evaluate the performance of two ARC control algorithms. To validate the ARC performance in a real vehicle, vehicle tests were conducted at KATECH proving ground using a small SUV equipped with two ARC actuators, upper and lower controllers and a few subsystems. From the simulation and vehicle validation test results, the proposed ARC control algorithm for the developed ARC actuator prototypes improves the vehicle’s dynamic performance.     

Old laws for new risks at sea: mineral resources, climate change, sea lanes, and cables

Maritime security in a broad sense means more than piracy and terrorism. This paper concentrates on the risk potential of current and future resource-related activities on the seabed. The seabed mining of hard mineral resources??in addition to hydrocarbons??leads to new controversial maritime boundary claims of states in their effort to expand national access rights to raw materials. Outer continental shelf claims in the Arctic Ocean are today's test bench for law of the sea conflicts. Fiber-optic cables running through regional seas, straits, and land bridges may become another risky issue, while the pattern of maritime transport routes is moving from Northern to Southern waters. Under a medium-term perspective, the sea level rise will endanger ports and coasts. Borderlines of maritime zones will move and thus generate more injustice and conflicts among states. The tools to solve borderline conflicts and options for dispute settlement are available in UNCLOS. Some other legal gaps are covered by the 2005 SUA Convention and by bilateral agreements, while resolutions by the UN Security Council begin to broaden rights of intervention and interdiction. The need for new laws remains.     

SAW焊接型剖面预报的模糊逻辑系统开发(英文)

A fuzzy model was presented to predict the weldment shape profile of submerged arc welds(SAW) including the shape of heat affected zone(HAZ).The SAW bead-on-plates were welded by following a full factorial design matrix.The design matrix consisted of three levels of input welding process parameters.The welds were cross-sectioned and etched,and the zones were measured.A mapping technique was used to measure the various segments of the weld zones.These mapped zones were used to build a fuzzy logic model.The membership functions of the fuzzy model were chosen for the accurate prediction of the weld zone.The fuzzy model was further tested for a set of test case data.The weld zone predicted by the fuzzy logic model was compared with the experimentally obtained shape profiles and close agreement between the two was noted.The mapping technique developed for the weld zones and the fuzzy logic model can be used for on-line control of the SAW process.From the SAW fuzzy logic model an estimation of the fusion and HAZ can also be developed.     

Performance of radial-type metal foam diesel particulate filters

An analytical study of the performance of a radial-type, metal foam diesel particulate filter is reported. A mathematical model for the filtration and regeneration of soot in a metal foam filter was developed. Nickel foam was selected for the filter medium due to its large specific area, high porosity, and high thermal resistance. For various metal foams, the filtration efficiency and the pressure drop through the filter were calculated, as was the deposition of soot. The results from the analytical model were compared with experimental data. In comparison with a conventional wall flow filter, the metal foam diesel particulate filter (DPF) is effective in utilizing the volume of material, due to the porous structures. As the size of the metal foam pores in the DPF increases from 580 μm to 800 μm, the filtration efficiency decreases from 90% to 50%, and the pressure drop decreases from 380 mbar to 20 mbar. The metal foam DPF with a large pore size is effective in utilizing the volume of material with a small pressure drop. The regeneration is completed within four minutes by the flow of hot exhaust gases under full load conditions.     

Effects of residual stresses on the static and fatigue strength of laser-welded lap joints with different welding speeds

This study was conducted to determine whether the different residual stresses caused by different welding speeds affect the static and fatigue strength of laser-welded lap joints. Residual stresses in STS301L laser-welded lap joints of different thicknesses under two laser-welding speed conditions, 4.1 m/min and 5.1 m/min, were evaluated with the incremental hole-drilling strain gage method at the middle of the heat-affected zone (HAZ). Then, static and fatigue tests were performed. The results show that higher static and fatigue strengths were obtained from the specimens welded with a 4.1 m/min welding speed than from the specimens welded at 5.1 m/min. The main difference was due to the compressive principal residual stress magnitude and its orientation near the HAZ. Also, the micro-hardness profile along the failure interface was measured to verify the static and fatigue failure behavior.     

Optimum SUV bumper system design considering pedestrian performance

Until recently, passenger cars have primarily interested in pedestrian protection performance. Nowadays, however, it is important for a sport-utility vehicle (SUV) to meet the bumper system standards for pedestrian safety. For a SUV bumper system, there are some difficulties in attaining a high level of pedestrian performance for the lower legform. An SUV has a high bumper position from the ground level, and the bumper approach angle must also be secured, which has an effect on car insurance fees. Due to these reasons, it is difficult to meet the pedestrian performance of the lower legform for an SUV. In this paper, a comparative study was performed on various SUV bumper systems, and a concept model for a SUV bumper system was developed, which is expected to meet the pedestrian performance by using the Pugh method. The design control factors were defined to affect the bumper pedestrian performance through the experiences of tests and analyses. For the noise factor to affect the pedestrian performance, the deviation of the impactor position was selected at the moment of impact. The design control factors were optimized by using the Taguchi optimization technique. For the Taguchi method, an L18 orthogonal array table of design control factors was used in the optimization process. Particularly, for the optimization of the bumper corner region, an optimization analysis was performed three times to meet pedestrian performance. Based on the results of the Taguchi optimization method, the sensitivity of the bumper design parameters was studied, and a new SUV bumper system is proposed that satisfies the pedestrian performance of the lower legform. The optimized bumper system should obtain a full Euro-NCAP score of 6 points for the bumper test. The pedestrian performance of the optimized bumper system is validated by using a CAE (Computer Aided Engineering) analysis, which has been proven to be in accurate. A comparison between the test and analysis results is shown for the validation of accuracy. By using the optimized bumper system, the tests and development costs of a bumper can be reduced.