Transport of radionuclides by sea-ice and dense-water formed in western Kara Sea flaw leads

A transport assessment of particle-bound and dissolved artificial radionuclides (¹³⁷Cs and ^239,240Pu) by sea-ice and dense-water formed in western Kara Sea flaw leads close to the Novaya Zemlya dumping sites is presented in this study. We both performed a “best estimate” based on available data, and a “maximum assessment” relying on simulated constant releases of 1 TBq ¹³⁷Cs and ^239,240Pu from individual dumping bays. The estimates are based on a combination of (i) the content of particulate matter in sea-ice; (ii) analytical data and numerical simulations of radionuclide concentrations in shelf surface deposits, suspended particulate matter (SPM), and the dissolved phase; and (iii) estimates of lead-ice and dense-water formation rates as well as modeling results of local ice drift pathways. In the “best estimate” case, 2.90 GBq ¹³⁷Cs and 0.51 GBq ^239,240Pu attached to sea-ice sediments can be exported from the lead areas toward the central Arctic basin. The radionuclide burden of the annually formed dense lead water in the “best estimate” amounts to 4.68 TBq ¹³⁷Cs and 0.014 TBq ^239,240Pu. In the “maximum assessment”, potential export-rates of ice-particle bound ¹³⁷Cs and ^239,240Pu toward the central Arctic would amount to 0.64 and 0.16 TBq, respectively. As much as ≈900 TBq ¹³⁷Cs and ≈6.75 TBq ^239,240Pu could be annually taken up by 34.75 dense-water rejected in the lead area. Assuming the (unlikely) instantaneous release of the total ¹³⁷Cs and ^239,240Pu inventories (≈1 PBq and 10 TBq, respectively) from the Novaya Zemlya dumping sites into the dissolved phase, the dense lead water locally formed during one winter season could take up ≈90% of the Cs and ≈68% of the Pu released.     

Influence of seabed sand wave on hydrodynamic performance of submersible北大核心CSCD

[目的]研究潜器在海底沙波地形干扰下的水动力特性。[方法]基于计算流体力学(CFD)方法,使用STAR-CCM+软件并结合重叠网格方法对潜器经过海底沙波的过程进行模拟,计算潜器阻力系数和升力系数在此过程中的变化。[结果]结果表明,当潜器近海底航行时,沙波地形会对潜器产生一定的干扰,当艏部运动至波峰附近时,负升力出现最大值,当艉部运动至波峰附近时,阻力出现最大值;在不同航速下,潜器表面压力分布规律的不同会导致升力系数的变化规律不同;随着近海底距离的减小,海底沙波对潜器阻力和升力变化影响显著,当H/D>5时,海底沙波对潜器阻力和升力的影响可以忽略。[结论]所做研究可为潜器的安全及操纵性能提供一定的参考。     

Application of slim A-pillar to improve driver’s field of vision

The importance of vehicle safety cannot be exaggerated in today’s mobile societies. Many manufacturers, associates related to vehicles and universities make an effort to improve vehicle safety by developing new technologies, applying high strength steel to the body structure etc. However, the majority of these efforts are focused on decreasing injury. It is absolutely important to minimize injury, but a more important aspect is coping with vehicle accidents. That is, As undeniably important as it is to minimize potential injuries, it is critical that experts focus on developing ways to keep drivers out of situations likely to lead to crashes in the first place. The purpose of this paper is to determine what the most critical factor is when coping with an unfamiliar driving situation. The answer is to provide a wide-open field of vision, especially for the driver. The driver’s field of vision is obstructed by the vehicle’s A-pillar. To solve this, the A-pillar obstruction angle, which is the angle between the driver’s eyes and the A-pillar should be decreased. This paper purposes three-methods for decreasing this angle structurally and applying a slim A-pillar which is as the best solution to decrease the A-pillar obstruction angle and ensure the drivers field of vision at the same time     

Crash protection of Hybrid Electrical Vehicles for amending the KMVSS No. 91

This paper explores issues related to the electrical safety of Hybrid Electrical Vehicles (HEVs) during and after various crash events. Japanese and American federal regulations regarding occupant protection against high voltages in Electric Vehicles (EVs) and HEVs were surveyed and analyzed in this study. Front, side and rear impact tests for two types of HEVs were conducted to investigate electrolyte spillage, the retention of the propulsion battery system and the electrical isolation of the occupant. The test results met the related criteria. The test procedures and the criteria for occupant protection established through this study were amended to Korean Motor Vehicle Safety Standard (KMVSS) No. 91 to add the crash protection of the EVs and the HEVs.     

Development of electrostatic diesel particulate matter filtration systems combined with a metallic Flow-Through Filter and electrostatic methods

A 3000 cc diesel engine attached to an engine dynamo was used to test three newly developed electrostatic Diesel Particulate matter filtration Systems (DPS 1, 2, and 3) under four steady-state engine operating conditions: idle, 2000 rpm with no load, and 2000 rpm under 25% and 50% loads. Of the two developed alternatives, DPS 1 and DPS 2, DPS 2 comprises an ionization section, electrostatic field additional section and Flow-Through Filter (FTF), which achieved almost 90% removal of particulate matter (PM) under the engine’s operating conditions, and the efficiency of the FTF was maintained between 20% and 50%. Comparing the long-term performance of DPS 2 and DPS 3 (effectively a serial combination of two DPS 2s) with a commercially-available Diesel Particulate Filter (DPF), the DPS 2 and DPS 3 achieved almost the same efficiency for removing PM as the DPF but had significantly improved (75%∼90% lower) differential pressure drops.     

Fault detection method for electric parking brake (EPB) systems with sensorless estimation using current ripples

A fault detection method with parity equations is proposed in this paper. Due to its low cost implementation, the velocity of the motor is not measurable in electric parking brake (EPB) systems. Therefore, residuals are not reliable when estimating the motor velocity with a low-resolution encoder. In this paper, we propose a fault detection method with sensorless estimation using current ripples that estimates the position and velocity of the motor by detecting periodical oscillations of the armature current caused by rotor slots. In addition, this method can estimate the position and velocity of the motor with less computational effort than a state observer. Moreover, the method is less sensitive to motor parameters than model-based estimation methods. The effectiveness of this method is validated with experimental data, and the simulation results show that various faults have their own residual patterns. Therefore, we can detect the presence of faults by monitoring the residual signals.     

Experimental research of the EQ6110HEV hybrid electric bus using an on-line debugging system

This paper describes the on-line debugging software developed by our research team. The software has five functions and can be helpful in achieving rapid development for hybrid electric buses. In addition, the software can monitor system states continuously and also modify parametric maps or update control programs using its on-line programming function. Based on the on-line debugging system, the hybrid propulsion control system is designed, and all the working modes of the hybrid electric bus are tested. Finally, experiments are carried out that verify that the debugging system is feasible and reliable. The test results show that the hybrid electric bus can reduce fuel consumption by about 19.1 percent, in comparison with conventional buses.     

Design of power split transmission: Design of dual mode power split transmission

The power split type hybrid system transmits engine power by dividing it into the electrical unit and the mechanical unit. Its power transmission efficiency is highest at the mechanical point (MP), where the full power is transmitted to the mechanical unit. In this study, the equation for the MP was derived for the gear ratios of a general 4-node lever model. The MP characteristics for the transmission ratio (TR) of the input split and compound split structures were examined using the equation derived. Using the examined input split and compound split structures, a systematic design method for the dual mode power split transmission was proposed. In the dual mode power split transmission, the MP could be positioned at the desired TR, and the input split and compound split modes could be selectively used according to the clutch combination, which leads to the operation of the vehicle within a high system efficiency range.     

Effects of injection parameters on the spray characteristics of swirl and slit injectors using the Mie-scattering method

We investigated the effects of injection parameters such as injection pressure, ambient pressure, and ambient temperature on spray characteristics. We calculated the turbulence occurring point (t _c ), defined as the time required to generate a vortex, and the deceleration point (t _b ), defined as the time when spray penetration begins to decelerate, to elucidate the breakup mechanism of the test injectors. The spray velocity coefficient (C_v) was obtained to evaluate the spray characteristics. As the ambient pressure increases in the case of a slit injector, C_v decreases. We investigated the effects of nozzle tip shape according to injection pressure, ambient pressure, and fuel properties on spray characteristics and provide a C_v value of 0.38 for the swirl injector with a spray angle of 60° and the slit injector under atmospheric conditions. The value of C_v in the case of a slit injector was reduced by increasing the ambient pressure. Our results suggest that C_v of a swirl injector is constant regardless of changes in ambient pressure, injection pressure, and fuel properties. On the other hand, C_v of a slit injector is altered by changes in ambient pressure.